Callovo-Oxfordian(COx)claystone has been considered as a potential host rock for geological radioactive waste disposal in France(Cigéo project).During the exploitation phase(100 years),the stability of drifts(e.g...Callovo-Oxfordian(COx)claystone has been considered as a potential host rock for geological radioactive waste disposal in France(Cigéo project).During the exploitation phase(100 years),the stability of drifts(e.g.galleries/alveoli)within the disposal is assured by the liner,which includes two layers:concrete arch segment and compressible material.The latter exhibits a significant deformation capacity(about 50%)under low stress(<3 MPa).Although the response of these underground structures can be governed by complex thermo-hydro-mechanical coupling,the creep behavior of COx claystone has been considered as the main factor controlling the increase of stress state in the concrete liner and hence the long-term stability of drifts.Therefore,by focusing only on the purely mechanical behavior,this study aims at investigating the uncertainty effect of the COx claystone time-dependent properties on the stability of an alveolus of Cigéo during the exploitation period.To describe the creep behavior of COx claystone,we use Lemaitre’s viscoplastic model with three parameters whose uncertainties are identified from laboratory creep tests.For the reliability analysis,an extension of a well-known Kriging metamodeling technique is proposed to assess the exceedance probability of acceptable stress in the concrete liner of the alveolus.The open-source code Code_Aster is chosen for the direct numerical evaluations of the performance function.The Kriging-based reliability analysis elucidates the effect of the uncertainty of COx claystone on the long-term stability of the concrete liner.Moreover,the role of the compressible material layer between the concrete liner and the host rock is also highlighted.展开更多
In this work, we synthesized cubic perovskite ceramics of the whole La_(1–x)Sr_xCoO_3(0 ≤ x ≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to re...In this work, we synthesized cubic perovskite ceramics of the whole La_(1–x)Sr_xCoO_3(0 ≤ x ≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to reach dense ceramics. For x > 0.8, it was necessary to substitute 3% cobalt by silicon to stabilize the cubic perovskite structure. Electrical conductivity increased with Sr content to reach 3×10~5 S·m^(–1) at 330 K for x = 0.3. However, the optimum electrical properties have been found for x = 0.05 at 330 K with PF_(max) = 3.11×10^(–4)W·m^(–1)·K^(–2). Indeed, the Seebeck coefficient was decreasing when x increased to reach values close to 0 for x ≥ 0.3. Thermal conductivity was low at low temperature(≈ 2.5 W×m^(–1)·K^(–1)) and increased up to 6.5 W·m^(–1)·K^(–1) when temperature increased. As the highest power factor was reached at low temperature as well as the lowest thermal conductivity, La_(1–x)Sr_xCoO_3 compounds with low x values appeared as very promising thermoelectric materials around room temperature, on the contrary to layered cobalt oxides. For high x values, Seebeck coefficient values close to zero made these materials unsuitable for thermoelectric applications.展开更多
The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in ...The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in air followed by annealing in a reducing atmosphere.XRD and SEM analyses show that the rutile TiO_(2 i)n Sr_(0.95)TiO_(3) formed after sintering becomes Magneli phase of TinO_(2n-1) after annealing.Moreover,Bi resolves from Sr1-xBixTiO_(3 )after annealing,resulting in the formation of Sr1-xBixTiO_(3-δ)/Bi/TinO_(2n-1) composites.With increasing Bi content in Sr1-xBixTiO_(3-δ),the electrical conductivity increases while the absolute values of the Seebeck coefficient decrease as a result of increasing carrier concentration.The thermal conductivity of SrTiO_(3-δ) is reduced by doping Bi up to x=0.07.Highest ZT~0.13 is obtained in Sr0.93Bi0.07TiO_(3-δ) at 1000 K.展开更多
Google's Bard has emerged as a formidable competitor to OpenAI's ChatGPT in the field of conversational AI.Notably,Bard has recently been updated to handle visual inputs alongside text prompts during conversat...Google's Bard has emerged as a formidable competitor to OpenAI's ChatGPT in the field of conversational AI.Notably,Bard has recently been updated to handle visual inputs alongside text prompts during conversations.Given Bard's impressive track record in handling textual inputs,we explore its capabilities in understanding and interpreting visual data(images)conditioned by text questions.This exploration holds the potential to unveil new insights and challenges for Bard and other forthcoming multi-modal Generative models,especially in addressing complex computer vision problems that demand accurate visual and language understanding.Specifically,in this study,we focus on 15 diverse task scenarios encompassing regular,camouflaged,medical,under-water and remote sensing data to comprehensively evaluate Bard's performance.Our primary finding indicates that Bard still struggles in these vision scenarios,highlighting the significant gap in vision-based understanding that needs to be bridged in future developments.We expect that this empirical study will prove valuable in advancing future models,leading to enhanced capabilities in comprehending and interpreting finegrained visual data.Our project is released on https://github.com/htqin/GoogleBard-VisUnderstand.展开更多
Concealed scene understanding(CSU)is a hot computer vision topic aiming to perceive objects exhibiting camouflage.The current boom in terms of techniques and applications warrants an up-to-date survey.This can help res...Concealed scene understanding(CSU)is a hot computer vision topic aiming to perceive objects exhibiting camouflage.The current boom in terms of techniques and applications warrants an up-to-date survey.This can help researchers better understand the global CSUfield,including both current achievements and remaining challenges.This paper makes four contributions:(1)For thefirst time,we present a comprehensive survey of deep learning techniques aimed at CSU,including a taxonomy,task-specific challenges,and ongoing developments.(2)To allow for an authoritative quantification of the state-of-the-art,we offer the largest and latest benchmark for concealed object segmentation(COS).(3)To evaluate the generalizability of deep CSU in practical scenarios,we collected the largest concealed defect segmentation dataset termed CDS2K with the hard cases from diversified industrial scenarios,on which we constructed a comprehensive benchmark.(4)We discuss open problems and potential research directions for CSU.展开更多
In geotechnical engineering,modeling geo-structures is challenging,particularly in cases where the interaction between the structures and soil or rock is complex.Most wellknown commercial modeling software is based on...In geotechnical engineering,modeling geo-structures is challenging,particularly in cases where the interaction between the structures and soil or rock is complex.Most wellknown commercial modeling software is based on homogenous and isotropic materials.However,soil and rock are often modeled in heterogeneous and anisotropic media because of the inherent anisotropy of sedimentary rock masses and their stratified structure.In recent decades,coupled hydro-mechanical(HM)interactions in isotropic porous media have been studied;however,the behavior of transversely isotropic porous media is rarely considered.In addition,it is difficult for commercial software such as Plaxis and Flac3D to express complex rock formation where the anisotropy of the material and the associated cracks and fractures could be assembled into a single model.In this study,a finite element implementation using Differential Equation Analysis Library(DEAL.II),an open-source library of finite element codes,was developed to model the fully coupled HM behavior of transversely isotropic porous media.The proposed implementation can be applied to both isotropic and transversely isotropic porous media based on Biot’s theory.The developed code can be used to model poroelastic media with(1)equations of linear elasticity for the solid matrix and(2)diffusion equations for fluid flow based on mass and linear-momentum conservation laws.We verified the performance and accuracy of the code through two examples,i.e.,Mandel’s problem with a compared analytical solution and a tunnel excavation process with the Flac3D software.On the basis of these numerical applications,we present the code to model the behavior of various geo-structures such as tunnels and pile–soil interactions with anisotropic materials.展开更多
The cactus is a plant that grows in many rural areas,widely used as a hedge,and has multiple benefits through the manufacture of various cosmetics and other products.However,this crop has been suffering for some time ...The cactus is a plant that grows in many rural areas,widely used as a hedge,and has multiple benefits through the manufacture of various cosmetics and other products.However,this crop has been suffering for some time from the attack of the carmine scaleDactylopius opuntia(Hemiptera:Dactylopiidae).The infestation can spread rapidly if not treated in the early stage.Current solutions consist of regular field checks by the naked eyes carried out by experts.The major difficulty is the lack of experts to check all fields,especially in remote areas.In addition,this requires time and resources.Hence the need for a system that can categorize the health level of cacti remotely.To date,deep learning models used to categorize plant diseases from images have not addressed the mealy bug infestation of cacti because computer vision has not sufficiently addressed this disease.Since there is no public dataset and smartphones are commonly used as tools to take pictures,it might then be conceivable for farmers to use them to categorize the infection level of their crops.In this work,we developed a system called CactiVIT that instantly determines the health status of cacti using the Visual image Transformer(ViT)model.We also provided a new image dataset of cochineal infested cacti.1 Finally,we developed a mobile application that delivers the classification results directly to farmers about the infestation in their fields by showing the probabilities related to each class.This study compares the existing models on the new dataset and presents the results obtained.The VIT-B-16 model reveals an approved performance in the literature and in our experiments,in which it achieved 88.73%overall accuracy with an average of+2.61%compared to other convolutional neural network(CNN)models that we evaluated under similar conditions.展开更多
In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering...In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering. Structural properties of La1-xBaxCoO3 were systematically investigated and thermoelectric properties were measured in the temperature range of 330–1000 K. The results show that the thermoelectric properties of Ba-substituted LaCoO3 depend on x. Indeed, at 330 K, electrical conductivity presents an optimum value for x = 0.25 with a value of σmax ≈ 2.2×105 S·m–1 whereas the Seebeck coefficient decreases when x and/or the temperature increases. The Ba-substituted LaCoO3 samples exhibit p-type semiconducting behaviour. The best power factor value found is 3.4×10–4 W·m–1·K–2 at 330 K for x = 0.075, which is 10% higher than the optimum value measured in La1–xSrxCoO3 for x = 0.05. The thermal diffusivity and thermal conductivity increase with increasing temperature and Ba concentration. La1-xBaxCoO3 shows a maximum figure of merit(ZT = 0.048) for x = 0.05 at 330 K, 25% higher than the best value in La1–xSrxCoO3 compounds.展开更多
文摘Callovo-Oxfordian(COx)claystone has been considered as a potential host rock for geological radioactive waste disposal in France(Cigéo project).During the exploitation phase(100 years),the stability of drifts(e.g.galleries/alveoli)within the disposal is assured by the liner,which includes two layers:concrete arch segment and compressible material.The latter exhibits a significant deformation capacity(about 50%)under low stress(<3 MPa).Although the response of these underground structures can be governed by complex thermo-hydro-mechanical coupling,the creep behavior of COx claystone has been considered as the main factor controlling the increase of stress state in the concrete liner and hence the long-term stability of drifts.Therefore,by focusing only on the purely mechanical behavior,this study aims at investigating the uncertainty effect of the COx claystone time-dependent properties on the stability of an alveolus of Cigéo during the exploitation period.To describe the creep behavior of COx claystone,we use Lemaitre’s viscoplastic model with three parameters whose uncertainties are identified from laboratory creep tests.For the reliability analysis,an extension of a well-known Kriging metamodeling technique is proposed to assess the exceedance probability of acceptable stress in the concrete liner of the alveolus.The open-source code Code_Aster is chosen for the direct numerical evaluations of the performance function.The Kriging-based reliability analysis elucidates the effect of the uncertainty of COx claystone on the long-term stability of the concrete liner.Moreover,the role of the compressible material layer between the concrete liner and the host rock is also highlighted.
基金ADEME(Agence de l'Environnement et de la Maitrise de l'Energie),Plan d'Investissment d'Avenir PIA"Tours 2015"for the financial support
文摘In this work, we synthesized cubic perovskite ceramics of the whole La_(1–x)Sr_xCoO_3(0 ≤ x ≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to reach dense ceramics. For x > 0.8, it was necessary to substitute 3% cobalt by silicon to stabilize the cubic perovskite structure. Electrical conductivity increased with Sr content to reach 3×10~5 S·m^(–1) at 330 K for x = 0.3. However, the optimum electrical properties have been found for x = 0.05 at 330 K with PF_(max) = 3.11×10^(–4)W·m^(–1)·K^(–2). Indeed, the Seebeck coefficient was decreasing when x increased to reach values close to 0 for x ≥ 0.3. Thermal conductivity was low at low temperature(≈ 2.5 W×m^(–1)·K^(–1)) and increased up to 6.5 W·m^(–1)·K^(–1) when temperature increased. As the highest power factor was reached at low temperature as well as the lowest thermal conductivity, La_(1–x)Sr_xCoO_3 compounds with low x values appeared as very promising thermoelectric materials around room temperature, on the contrary to layered cobalt oxides. For high x values, Seebeck coefficient values close to zero made these materials unsuitable for thermoelectric applications.
文摘The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in air followed by annealing in a reducing atmosphere.XRD and SEM analyses show that the rutile TiO_(2 i)n Sr_(0.95)TiO_(3) formed after sintering becomes Magneli phase of TinO_(2n-1) after annealing.Moreover,Bi resolves from Sr1-xBixTiO_(3 )after annealing,resulting in the formation of Sr1-xBixTiO_(3-δ)/Bi/TinO_(2n-1) composites.With increasing Bi content in Sr1-xBixTiO_(3-δ),the electrical conductivity increases while the absolute values of the Seebeck coefficient decrease as a result of increasing carrier concentration.The thermal conductivity of SrTiO_(3-δ) is reduced by doping Bi up to x=0.07.Highest ZT~0.13 is obtained in Sr0.93Bi0.07TiO_(3-δ) at 1000 K.
文摘Google's Bard has emerged as a formidable competitor to OpenAI's ChatGPT in the field of conversational AI.Notably,Bard has recently been updated to handle visual inputs alongside text prompts during conversations.Given Bard's impressive track record in handling textual inputs,we explore its capabilities in understanding and interpreting visual data(images)conditioned by text questions.This exploration holds the potential to unveil new insights and challenges for Bard and other forthcoming multi-modal Generative models,especially in addressing complex computer vision problems that demand accurate visual and language understanding.Specifically,in this study,we focus on 15 diverse task scenarios encompassing regular,camouflaged,medical,under-water and remote sensing data to comprehensively evaluate Bard's performance.Our primary finding indicates that Bard still struggles in these vision scenarios,highlighting the significant gap in vision-based understanding that needs to be bridged in future developments.We expect that this empirical study will prove valuable in advancing future models,leading to enhanced capabilities in comprehending and interpreting finegrained visual data.Our project is released on https://github.com/htqin/GoogleBard-VisUnderstand.
基金Deng-Ping Fan and Christos Sakaridis are funded by Toyota Motor Europe(research project TRACE-Zurich).
文摘Concealed scene understanding(CSU)is a hot computer vision topic aiming to perceive objects exhibiting camouflage.The current boom in terms of techniques and applications warrants an up-to-date survey.This can help researchers better understand the global CSUfield,including both current achievements and remaining challenges.This paper makes four contributions:(1)For thefirst time,we present a comprehensive survey of deep learning techniques aimed at CSU,including a taxonomy,task-specific challenges,and ongoing developments.(2)To allow for an authoritative quantification of the state-of-the-art,we offer the largest and latest benchmark for concealed object segmentation(COS).(3)To evaluate the generalizability of deep CSU in practical scenarios,we collected the largest concealed defect segmentation dataset termed CDS2K with the hard cases from diversified industrial scenarios,on which we constructed a comprehensive benchmark.(4)We discuss open problems and potential research directions for CSU.
文摘In geotechnical engineering,modeling geo-structures is challenging,particularly in cases where the interaction between the structures and soil or rock is complex.Most wellknown commercial modeling software is based on homogenous and isotropic materials.However,soil and rock are often modeled in heterogeneous and anisotropic media because of the inherent anisotropy of sedimentary rock masses and their stratified structure.In recent decades,coupled hydro-mechanical(HM)interactions in isotropic porous media have been studied;however,the behavior of transversely isotropic porous media is rarely considered.In addition,it is difficult for commercial software such as Plaxis and Flac3D to express complex rock formation where the anisotropy of the material and the associated cracks and fractures could be assembled into a single model.In this study,a finite element implementation using Differential Equation Analysis Library(DEAL.II),an open-source library of finite element codes,was developed to model the fully coupled HM behavior of transversely isotropic porous media.The proposed implementation can be applied to both isotropic and transversely isotropic porous media based on Biot’s theory.The developed code can be used to model poroelastic media with(1)equations of linear elasticity for the solid matrix and(2)diffusion equations for fluid flow based on mass and linear-momentum conservation laws.We verified the performance and accuracy of the code through two examples,i.e.,Mandel’s problem with a compared analytical solution and a tunnel excavation process with the Flac3D software.On the basis of these numerical applications,we present the code to model the behavior of various geo-structures such as tunnels and pile–soil interactions with anisotropic materials.
基金PHC Toubkal/21/121-Campus France:45942UG who funded the work and the mobility fee between Morocco and France.
文摘The cactus is a plant that grows in many rural areas,widely used as a hedge,and has multiple benefits through the manufacture of various cosmetics and other products.However,this crop has been suffering for some time from the attack of the carmine scaleDactylopius opuntia(Hemiptera:Dactylopiidae).The infestation can spread rapidly if not treated in the early stage.Current solutions consist of regular field checks by the naked eyes carried out by experts.The major difficulty is the lack of experts to check all fields,especially in remote areas.In addition,this requires time and resources.Hence the need for a system that can categorize the health level of cacti remotely.To date,deep learning models used to categorize plant diseases from images have not addressed the mealy bug infestation of cacti because computer vision has not sufficiently addressed this disease.Since there is no public dataset and smartphones are commonly used as tools to take pictures,it might then be conceivable for farmers to use them to categorize the infection level of their crops.In this work,we developed a system called CactiVIT that instantly determines the health status of cacti using the Visual image Transformer(ViT)model.We also provided a new image dataset of cochineal infested cacti.1 Finally,we developed a mobile application that delivers the classification results directly to farmers about the infestation in their fields by showing the probabilities related to each class.This study compares the existing models on the new dataset and presents the results obtained.The VIT-B-16 model reveals an approved performance in the literature and in our experiments,in which it achieved 88.73%overall accuracy with an average of+2.61%compared to other convolutional neural network(CNN)models that we evaluated under similar conditions.
基金Programme d‘Investissment d’Avenir PIA“Tours 2015”for the financial support
文摘In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering. Structural properties of La1-xBaxCoO3 were systematically investigated and thermoelectric properties were measured in the temperature range of 330–1000 K. The results show that the thermoelectric properties of Ba-substituted LaCoO3 depend on x. Indeed, at 330 K, electrical conductivity presents an optimum value for x = 0.25 with a value of σmax ≈ 2.2×105 S·m–1 whereas the Seebeck coefficient decreases when x and/or the temperature increases. The Ba-substituted LaCoO3 samples exhibit p-type semiconducting behaviour. The best power factor value found is 3.4×10–4 W·m–1·K–2 at 330 K for x = 0.075, which is 10% higher than the optimum value measured in La1–xSrxCoO3 for x = 0.05. The thermal diffusivity and thermal conductivity increase with increasing temperature and Ba concentration. La1-xBaxCoO3 shows a maximum figure of merit(ZT = 0.048) for x = 0.05 at 330 K, 25% higher than the best value in La1–xSrxCoO3 compounds.
