yves remond | Université de Strasbourg (original) (raw)
Papers by yves remond
2019 7th International Renewable and Sustainable Energy Conference (IRSEC)
In this study, a pragmatic engineering approach is proposed to assist in addressing the high-powe... more In this study, a pragmatic engineering approach is proposed to assist in addressing the high-power consumption for cooling specifically, peak demand issues in countries with desert climate conditions. In this approach, an improved control scheme for cooling buildings is developed to minimize load peak demand by managing to space cooling demands in a more holistic organized manner rather than being randomly managed. In addition, a mathematical model of a typical house cooling system is developed along with a complex multi-mode logic controller. Finally, The simulation results demonstrate the ability of the proposed control scheme to considerably reduce power peaks while maintaining an adequate level of indoor comfort.
The Cleft Palate-Craniofacial Journal, 2021
Introduction: Since the early stages of alveolar bone grafting development, multiple types of mat... more Introduction: Since the early stages of alveolar bone grafting development, multiple types of materials have been used. Iliac cancellous bone graft (ICBG) remains the gold standard. Design/Methods: A review of literature is conducted in order to describe the different bone filling possibilities, autologous or not, and to assess their effectiveness compared to ICBG. This review focused on studies reporting volumetric assessment of the alveolar cleft graft result (by computed tomography scan or cone beam computed tomography). Results: Grafting materials fall into 3 types: autologous bone grafts, ICBG supplementary material, and bone substitutes. Among autologous materials, no study showed the superiority of any other bone origin over iliac cancellous bone. Yet ICBG gives inconsistent results and presents donor site morbidity. Concerning supplementary material, only 3 studies could show a benefit of adding platelet-rich fibrin (1 study) or platelet-rich plasma (2 studies) to ICBG, whic...
Mathematics and Mechanics of Complex Systems, 2018
Bone remodelling is a complex phenomenon during which old and damage bone is removed and replaced... more Bone remodelling is a complex phenomenon during which old and damage bone is removed and replaced with new one to ensure the physiological functions of the skeletal system. It involves many biological, mechanical, chemical processes at different scales. The objective of the present work is to predict the kinetics of bone density evolution by taking into account both the mechanical and the biological frameworks. In order to do so, we propose a new computational model in which the global stimulus triggering bone remodelling is the result of the contribution of a mechanical (i.e. external loads and consequent strain energy), a cellular (i.e. osteoblasts and osteoclasts activities) and a molecular (i.e. oxygen and glucose supply) stimulus. The evolution of the bone density depends on the overall behaviour of the global stimulus. More specifically, when the global stimulus is positive, bone synthesis occurs, whereas when the global stimulus is negative, resorption takes place. Although the theoretical model has been applied on a very simple two-dimensional geometry, the final results provide new insights on the influence of each stimulus on the bone remodelling process. In particular, we confirm that mechanics plays a critical role and affects the kinetics of bone reconstruction, but it highly depends on the biological events and the distribution of bone density. Communicated by Francesco dell'Isola. MSC2010: 65M99.
Journal of Cellular Immunotherapy, 2018
Iranian Journal of Science and Technology, Transactions of Mechanical Engineering, 2018
In this paper, a micromechanical approach is employed to propose a cerebral cortex tissue represe... more In this paper, a micromechanical approach is employed to propose a cerebral cortex tissue representative volume element (RVE) and simulate the mechanical behavior of this type of tissue in different loadings. In this regard, a MATLAB code is developed to homogenize a random distribution of neurons in the extracellular matrix. To create the RVE, different inputs including the size of RVE, the number of neurons, the radius of the neuron cell body, the coordinates of the axon and dendrites of a neuron, the radius of the axon and dendrites, and the minimum distance between the cellular volumes are considered. Then, a PYTHON code is developed which generates the desired RVE in ABAQUS employing the outputs of the MATLAB code. Also, a viscoelastic material model is considered for material components of the cerebral cortex tissue in this study. To analyze the developed RVE, some relaxation tests are performed on the RVE. Strain rate, neuron volume fraction (NVF), loading time and neuron distribution are investigated in different stress relaxation tests on the developed RVEs. Considering the NVF of 1, 2 and 3%, it is concluded that the maximum tensile and compressive stresses rise by increasing the NVF. Also, the results demonstrate that different irregular distributions of neurons have no effect on the bulk mechanical properties of the tissue for a constant NVF and only affect the distribution of local stresses (and even the maximum stress) in the tissue. Finally, the numerical simulations revealed that the developed RVE is a robust element which can be employed in realistic model of the brain tissue in different loading conditions such as trauma. Keywords Micromechanical modeling Á Cerebral cortex tissue Á Neuron Á Extracellular matrix Á Representative volume element (RVE)
Aerosol Science and Technology, 2018
Field studies of dry deposition usually measure dust accumulation over periods of days or weeks. ... more Field studies of dry deposition usually measure dust accumulation over periods of days or weeks. However, long measurement periods obscure the effects of meteorological conditions on the deposition rate. Previously we developed an "outdoor soiling microscope" (OSM) in order to measure dust deposition and detachment every 10 min in the field. In this study a greased/ ungreased pair of OSMs was deployed for 51 days in the desert climate of Doha, Qatar. Stepwise regression analysis was performed to quantify the explanatory power of meteorological parameters on dust deposition and detachment rates. It was found that wind speed dominated deposition and rebound of dust particles, and produced a distinctive "threshold" response in deposition. The dry deposition results were highly consistent with a model by Kim et al. (2000) derived from outdoor experiments. By comparison, relative humidity and particulate matter concentration had less influence on dust flux rates.
Many models have been developed to predict the large strain behavior of amorphous polymers. These... more Many models have been developed to predict the large strain behavior of amorphous polymers. These models give good results for simple loading conditions such as uniaxial tension or compression. However, 3D mechanical loads are more complex to model and simulate using finite transformations. The classical logarithmic measure of strain requires the use of a stress that accounts for the complex transport phenomenon out of the principal directions. This work proposes an original modeling of amorphous polymers within this framework together with numerical simulations accounting of these transports. Particularly interesting results are obtained clearly distinguishing the situations with important shear loading. Mots clefs : modélisation, polymères amorphes, opérateurs de transport, grandes déformations
2016 International Renewable and Sustainable Energy Conference (IRSEC)
Soiling can greatly decrease the performance of PV systems in desert regions. There are different... more Soiling can greatly decrease the performance of PV systems in desert regions. There are different ways of measuring soiling in the field and laboratory, such as mass of dust deposited, light transmission reduction, or output of a PV cell. A review of common PV soiling measurement techniques is presented. Also, sunlight angle of incidence is shown experimentally to affect the apparent soiling loss of a PV array with high dust load, which may impact comparison of such measurements taken at different times of year.
Continuum Mechanics and Thermodynamics
The development of multiphysics numerical models to predict bone reconstruction is a very challen... more The development of multiphysics numerical models to predict bone reconstruction is a very challenging task as it is a complex phenomenon where many biological, chemical and mechanical processes occur at different lengths and timescales. We present here a mechanobiological theoretical numerical model accounting for both the mechanical and biological environments to predict the bone reconstruction process through the use of a global stimulus integrating the contributions of applied external mechanical loads, cellular activities and cellular nutriments such as oxygen and glucose supply. The bone density evolution will hence depend on the overall stimulus and evolve accordingly to the intensities of each of its individual constituents. We show their specific influences and couplings on a simple two-dimensional geometry and confirm that, although the mechanics plays a crucial role in the bone reconstruction process, it is still highly dependent on the occurring biological events and will evolve accordingly.
Mathematics and Mechanics of Solids
In this paper we numerically simulate the phenomenon of bone growth in bone defects as driven by ... more In this paper we numerically simulate the phenomenon of bone growth in bone defects as driven by external mechanical excitation. Bone growth is accounted for through a continuum model that allows simulation of the filling of a defect. The influence of the model boundary conditions is also discussed. Two and three dimensional simulations are presented, explicitly showing the bone regeneration process inside the cavity on a weekly basis. Numerical results are qualitatively compared with literature experimental data from a rat calvarial defect exposed to low-intensity pulsed ultrasound. The obtained results show trend correlations with the targeted phenomenological observations and allow us to perform a first evaluation of the proposed model parameters to be optimized for clinically relevant situations, even if a systematic experimental campaign is still needed to precisely identify the bio-mechanical parameters involved.
Bio-medical materials and engineering, 2017
Although orthodontics have greatly improved over the years, understanding of its associated biome... more Although orthodontics have greatly improved over the years, understanding of its associated biomechanics remains incomplete and is mainly based on two dimensional (2D) mechanical equilibrium and long-time clinical experience. Little experimental information exists in three dimensions (3D) about the forces and moments developed on orthodontic brackets over more than two or three adjacent teeth. We define here a simplified methodology to quantify 3D forces and moments applied on orthodontic brackets fixed on a dental arch and validate our methodology using existing results from the literature by means of simplified hypotheses.
Bio-medical materials and engineering, 2017
Orthodontic appliances deliver forces and moments that will determine movement of teeth. To analy... more Orthodontic appliances deliver forces and moments that will determine movement of teeth. To analyze this latter, we developed an experimental setup to measure the mechanical forces applied on the teeth and to calculate, through a simplified theoretical analysis, the reactive forces and corresponding moments onto the brackets of three adjacent teeth. To validate the theoretical and experimental results, we use a simplified clinical situation of a maxillary canine in infraclusion and surrounded by its corresponding upper lateral incisor and first premolar. Forces are then measured experimentally and compared with the calculated results. From this, we show the specific dissymmetry of the mechanical forces on each side of the maxillary canine due to the applied mechanical forces and the undesirable induced generated moments occurring on each tooth that will directly impact the bone remodeling process and the final tooth repositioning.
Comptes Rendus de l'Académie des Sciences - Series IIB - Mechanics-Physics-Astronomy, 1999
The calculation of a given gear train (solution of the direct problem) is never really difficult,... more The calculation of a given gear train (solution of the direct problem) is never really difficult, but does not give one any idea how it was invented. Since the inverse problem (i.e. obtaining the concept if the kinematics are fixed) has never been approached in an analytical way, we propose, from the general formula of the ratios, a single equation
The effect of reprocessing on the quasi-static uniaxial tensile behavior of two commercial polypr... more 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 including a grinding step and an extrusion step to simulate recycling at the laboratory level, the selected reprocessing numbers for this study being 0, 3, 6, 9 and 12. Because the repeated reprocessing leads to thermo-mechanical degradation by chain scission mechanisms, the tensile behavior of the two materials exhibits a continuous decrease of elastic modulus and failure strain with increasing number of reprocessing. A physically consistent three-dimensional constitutive model is used to predict the tensile response of non-recycled materials with strain rate dependence. For the recycled materials, the reprocessing effect is accounted by incorp...
Solar Energy
Abstract Condensation contributes to soiling of photovoltaic modules by trapping dust particles a... more Abstract Condensation contributes to soiling of photovoltaic modules by trapping dust particles and, in certain conditions, leaving a material bridge between particles and the surface after evaporating. This study investigated the effects of four parameters on condensation on soiled surfaces: (i) relative humidity (RH), (ii) surface–dew point temperature difference, (iii) hygroscopic dust content, and (iv) surface wettability. Natural and synthetic dust mixtures of various compositions were studied via water adsorption isotherms, XRD, ion chromatography and optical microscopy, on hydrophilic and hydrophobic surfaces, in the lab and field. It was found that water uptake by surface dust was strongly dependent on its content of hygroscopic material, and such material allowed microscopic condensation droplets to exist on a soiled glass coupon even when it was significantly warmer than the dew point. A hydrophobic PTFE surface did not greatly retard the onset of condensation, compared to a glass surface, but did inhibit its growth. The implications for anti-soiling coatings are that it would be a difficult goal to eliminate condensation, and their performance will be influenced by dust composition and factors affecting condensation run-off such as RH and tilt angle. Variation in such parameters may partly explain inconsistent results from coating field trials reported so far.
Oil & Gas Science and Technology - Revue de l'IFP, 2006
Mechanics of Materials, 2013
ABSTRACT Montmorillonite clays are one of the most used nano-reinforcement in polypropylene nanoc... more ABSTRACT Montmorillonite clays are one of the most used nano-reinforcement in polypropylene nanocomposite systems, which can enhance the mechanical properties with a low volume fraction. In this study, the nanocomposites were obtained by using a melt mixing technique. Dynamic mechanical analysis (DMA) was realized to investigate the elastic behavior of pure polypropylene and polypropylene based organoclay nanocomposites. Previous results from high strain rate uniaxial compression tests (split Hopkinson pressure bar) are also used in this study. Two micromechanical models, based on two-phase and three-phase composite approaches, were incorporated into a statistical model to describe the dependence of the elastic modulus on the test temperature, frequency/strain rate, volume fraction of organoclay and on the extent of exfoliation. The predictions of the nanocomposite elastic modulus by both models showed a good agreement with experimental results. The estimated average particle thicknesses, from the proposed modeling, indicate a decrease of the exfoliation degree with the increase of fillers' volume fraction. This extent of exfoliation trend reflects well the results by the transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements conducted in a previous work.
Journal of Mechanics of Materials and Structures, 2012
2019 7th International Renewable and Sustainable Energy Conference (IRSEC)
In this study, a pragmatic engineering approach is proposed to assist in addressing the high-powe... more In this study, a pragmatic engineering approach is proposed to assist in addressing the high-power consumption for cooling specifically, peak demand issues in countries with desert climate conditions. In this approach, an improved control scheme for cooling buildings is developed to minimize load peak demand by managing to space cooling demands in a more holistic organized manner rather than being randomly managed. In addition, a mathematical model of a typical house cooling system is developed along with a complex multi-mode logic controller. Finally, The simulation results demonstrate the ability of the proposed control scheme to considerably reduce power peaks while maintaining an adequate level of indoor comfort.
The Cleft Palate-Craniofacial Journal, 2021
Introduction: Since the early stages of alveolar bone grafting development, multiple types of mat... more Introduction: Since the early stages of alveolar bone grafting development, multiple types of materials have been used. Iliac cancellous bone graft (ICBG) remains the gold standard. Design/Methods: A review of literature is conducted in order to describe the different bone filling possibilities, autologous or not, and to assess their effectiveness compared to ICBG. This review focused on studies reporting volumetric assessment of the alveolar cleft graft result (by computed tomography scan or cone beam computed tomography). Results: Grafting materials fall into 3 types: autologous bone grafts, ICBG supplementary material, and bone substitutes. Among autologous materials, no study showed the superiority of any other bone origin over iliac cancellous bone. Yet ICBG gives inconsistent results and presents donor site morbidity. Concerning supplementary material, only 3 studies could show a benefit of adding platelet-rich fibrin (1 study) or platelet-rich plasma (2 studies) to ICBG, whic...
Mathematics and Mechanics of Complex Systems, 2018
Bone remodelling is a complex phenomenon during which old and damage bone is removed and replaced... more Bone remodelling is a complex phenomenon during which old and damage bone is removed and replaced with new one to ensure the physiological functions of the skeletal system. It involves many biological, mechanical, chemical processes at different scales. The objective of the present work is to predict the kinetics of bone density evolution by taking into account both the mechanical and the biological frameworks. In order to do so, we propose a new computational model in which the global stimulus triggering bone remodelling is the result of the contribution of a mechanical (i.e. external loads and consequent strain energy), a cellular (i.e. osteoblasts and osteoclasts activities) and a molecular (i.e. oxygen and glucose supply) stimulus. The evolution of the bone density depends on the overall behaviour of the global stimulus. More specifically, when the global stimulus is positive, bone synthesis occurs, whereas when the global stimulus is negative, resorption takes place. Although the theoretical model has been applied on a very simple two-dimensional geometry, the final results provide new insights on the influence of each stimulus on the bone remodelling process. In particular, we confirm that mechanics plays a critical role and affects the kinetics of bone reconstruction, but it highly depends on the biological events and the distribution of bone density. Communicated by Francesco dell'Isola. MSC2010: 65M99.
Journal of Cellular Immunotherapy, 2018
Iranian Journal of Science and Technology, Transactions of Mechanical Engineering, 2018
In this paper, a micromechanical approach is employed to propose a cerebral cortex tissue represe... more In this paper, a micromechanical approach is employed to propose a cerebral cortex tissue representative volume element (RVE) and simulate the mechanical behavior of this type of tissue in different loadings. In this regard, a MATLAB code is developed to homogenize a random distribution of neurons in the extracellular matrix. To create the RVE, different inputs including the size of RVE, the number of neurons, the radius of the neuron cell body, the coordinates of the axon and dendrites of a neuron, the radius of the axon and dendrites, and the minimum distance between the cellular volumes are considered. Then, a PYTHON code is developed which generates the desired RVE in ABAQUS employing the outputs of the MATLAB code. Also, a viscoelastic material model is considered for material components of the cerebral cortex tissue in this study. To analyze the developed RVE, some relaxation tests are performed on the RVE. Strain rate, neuron volume fraction (NVF), loading time and neuron distribution are investigated in different stress relaxation tests on the developed RVEs. Considering the NVF of 1, 2 and 3%, it is concluded that the maximum tensile and compressive stresses rise by increasing the NVF. Also, the results demonstrate that different irregular distributions of neurons have no effect on the bulk mechanical properties of the tissue for a constant NVF and only affect the distribution of local stresses (and even the maximum stress) in the tissue. Finally, the numerical simulations revealed that the developed RVE is a robust element which can be employed in realistic model of the brain tissue in different loading conditions such as trauma. Keywords Micromechanical modeling Á Cerebral cortex tissue Á Neuron Á Extracellular matrix Á Representative volume element (RVE)
Aerosol Science and Technology, 2018
Field studies of dry deposition usually measure dust accumulation over periods of days or weeks. ... more Field studies of dry deposition usually measure dust accumulation over periods of days or weeks. However, long measurement periods obscure the effects of meteorological conditions on the deposition rate. Previously we developed an "outdoor soiling microscope" (OSM) in order to measure dust deposition and detachment every 10 min in the field. In this study a greased/ ungreased pair of OSMs was deployed for 51 days in the desert climate of Doha, Qatar. Stepwise regression analysis was performed to quantify the explanatory power of meteorological parameters on dust deposition and detachment rates. It was found that wind speed dominated deposition and rebound of dust particles, and produced a distinctive "threshold" response in deposition. The dry deposition results were highly consistent with a model by Kim et al. (2000) derived from outdoor experiments. By comparison, relative humidity and particulate matter concentration had less influence on dust flux rates.
Many models have been developed to predict the large strain behavior of amorphous polymers. These... more Many models have been developed to predict the large strain behavior of amorphous polymers. These models give good results for simple loading conditions such as uniaxial tension or compression. However, 3D mechanical loads are more complex to model and simulate using finite transformations. The classical logarithmic measure of strain requires the use of a stress that accounts for the complex transport phenomenon out of the principal directions. This work proposes an original modeling of amorphous polymers within this framework together with numerical simulations accounting of these transports. Particularly interesting results are obtained clearly distinguishing the situations with important shear loading. Mots clefs : modélisation, polymères amorphes, opérateurs de transport, grandes déformations
2016 International Renewable and Sustainable Energy Conference (IRSEC)
Soiling can greatly decrease the performance of PV systems in desert regions. There are different... more Soiling can greatly decrease the performance of PV systems in desert regions. There are different ways of measuring soiling in the field and laboratory, such as mass of dust deposited, light transmission reduction, or output of a PV cell. A review of common PV soiling measurement techniques is presented. Also, sunlight angle of incidence is shown experimentally to affect the apparent soiling loss of a PV array with high dust load, which may impact comparison of such measurements taken at different times of year.
Continuum Mechanics and Thermodynamics
The development of multiphysics numerical models to predict bone reconstruction is a very challen... more The development of multiphysics numerical models to predict bone reconstruction is a very challenging task as it is a complex phenomenon where many biological, chemical and mechanical processes occur at different lengths and timescales. We present here a mechanobiological theoretical numerical model accounting for both the mechanical and biological environments to predict the bone reconstruction process through the use of a global stimulus integrating the contributions of applied external mechanical loads, cellular activities and cellular nutriments such as oxygen and glucose supply. The bone density evolution will hence depend on the overall stimulus and evolve accordingly to the intensities of each of its individual constituents. We show their specific influences and couplings on a simple two-dimensional geometry and confirm that, although the mechanics plays a crucial role in the bone reconstruction process, it is still highly dependent on the occurring biological events and will evolve accordingly.
Mathematics and Mechanics of Solids
In this paper we numerically simulate the phenomenon of bone growth in bone defects as driven by ... more In this paper we numerically simulate the phenomenon of bone growth in bone defects as driven by external mechanical excitation. Bone growth is accounted for through a continuum model that allows simulation of the filling of a defect. The influence of the model boundary conditions is also discussed. Two and three dimensional simulations are presented, explicitly showing the bone regeneration process inside the cavity on a weekly basis. Numerical results are qualitatively compared with literature experimental data from a rat calvarial defect exposed to low-intensity pulsed ultrasound. The obtained results show trend correlations with the targeted phenomenological observations and allow us to perform a first evaluation of the proposed model parameters to be optimized for clinically relevant situations, even if a systematic experimental campaign is still needed to precisely identify the bio-mechanical parameters involved.
Bio-medical materials and engineering, 2017
Although orthodontics have greatly improved over the years, understanding of its associated biome... more Although orthodontics have greatly improved over the years, understanding of its associated biomechanics remains incomplete and is mainly based on two dimensional (2D) mechanical equilibrium and long-time clinical experience. Little experimental information exists in three dimensions (3D) about the forces and moments developed on orthodontic brackets over more than two or three adjacent teeth. We define here a simplified methodology to quantify 3D forces and moments applied on orthodontic brackets fixed on a dental arch and validate our methodology using existing results from the literature by means of simplified hypotheses.
Bio-medical materials and engineering, 2017
Orthodontic appliances deliver forces and moments that will determine movement of teeth. To analy... more Orthodontic appliances deliver forces and moments that will determine movement of teeth. To analyze this latter, we developed an experimental setup to measure the mechanical forces applied on the teeth and to calculate, through a simplified theoretical analysis, the reactive forces and corresponding moments onto the brackets of three adjacent teeth. To validate the theoretical and experimental results, we use a simplified clinical situation of a maxillary canine in infraclusion and surrounded by its corresponding upper lateral incisor and first premolar. Forces are then measured experimentally and compared with the calculated results. From this, we show the specific dissymmetry of the mechanical forces on each side of the maxillary canine due to the applied mechanical forces and the undesirable induced generated moments occurring on each tooth that will directly impact the bone remodeling process and the final tooth repositioning.
Comptes Rendus de l'Académie des Sciences - Series IIB - Mechanics-Physics-Astronomy, 1999
The calculation of a given gear train (solution of the direct problem) is never really difficult,... more The calculation of a given gear train (solution of the direct problem) is never really difficult, but does not give one any idea how it was invented. Since the inverse problem (i.e. obtaining the concept if the kinematics are fixed) has never been approached in an analytical way, we propose, from the general formula of the ratios, a single equation
The effect of reprocessing on the quasi-static uniaxial tensile behavior of two commercial polypr... more 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 including a grinding step and an extrusion step to simulate recycling at the laboratory level, the selected reprocessing numbers for this study being 0, 3, 6, 9 and 12. Because the repeated reprocessing leads to thermo-mechanical degradation by chain scission mechanisms, the tensile behavior of the two materials exhibits a continuous decrease of elastic modulus and failure strain with increasing number of reprocessing. A physically consistent three-dimensional constitutive model is used to predict the tensile response of non-recycled materials with strain rate dependence. For the recycled materials, the reprocessing effect is accounted by incorp...
Solar Energy
Abstract Condensation contributes to soiling of photovoltaic modules by trapping dust particles a... more Abstract Condensation contributes to soiling of photovoltaic modules by trapping dust particles and, in certain conditions, leaving a material bridge between particles and the surface after evaporating. This study investigated the effects of four parameters on condensation on soiled surfaces: (i) relative humidity (RH), (ii) surface–dew point temperature difference, (iii) hygroscopic dust content, and (iv) surface wettability. Natural and synthetic dust mixtures of various compositions were studied via water adsorption isotherms, XRD, ion chromatography and optical microscopy, on hydrophilic and hydrophobic surfaces, in the lab and field. It was found that water uptake by surface dust was strongly dependent on its content of hygroscopic material, and such material allowed microscopic condensation droplets to exist on a soiled glass coupon even when it was significantly warmer than the dew point. A hydrophobic PTFE surface did not greatly retard the onset of condensation, compared to a glass surface, but did inhibit its growth. The implications for anti-soiling coatings are that it would be a difficult goal to eliminate condensation, and their performance will be influenced by dust composition and factors affecting condensation run-off such as RH and tilt angle. Variation in such parameters may partly explain inconsistent results from coating field trials reported so far.
Oil & Gas Science and Technology - Revue de l'IFP, 2006
Mechanics of Materials, 2013
ABSTRACT Montmorillonite clays are one of the most used nano-reinforcement in polypropylene nanoc... more ABSTRACT Montmorillonite clays are one of the most used nano-reinforcement in polypropylene nanocomposite systems, which can enhance the mechanical properties with a low volume fraction. In this study, the nanocomposites were obtained by using a melt mixing technique. Dynamic mechanical analysis (DMA) was realized to investigate the elastic behavior of pure polypropylene and polypropylene based organoclay nanocomposites. Previous results from high strain rate uniaxial compression tests (split Hopkinson pressure bar) are also used in this study. Two micromechanical models, based on two-phase and three-phase composite approaches, were incorporated into a statistical model to describe the dependence of the elastic modulus on the test temperature, frequency/strain rate, volume fraction of organoclay and on the extent of exfoliation. The predictions of the nanocomposite elastic modulus by both models showed a good agreement with experimental results. The estimated average particle thicknesses, from the proposed modeling, indicate a decrease of the exfoliation degree with the increase of fillers' volume fraction. This extent of exfoliation trend reflects well the results by the transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements conducted in a previous work.
Journal of Mechanics of Materials and Structures, 2012