Skirted foundations are usually used in marine engineering.More researches revealed that the variations in soil undrained shear strength considerably influence the assessing performance of the bearing capacity of skir...Skirted foundations are usually used in marine engineering.More researches revealed that the variations in soil undrained shear strength considerably influence the assessing performance of the bearing capacity of skirted foundations.This study proposes two machine learning-based methods to predict safety factors(F_(s))of skirted foundations under combined loadings.By comparing the prediction performance of models based on Convolutional Neural Networks(CNN)and Gaussian Process Regression,this study investigates the effect of input size of soil random field on prediction accuracy and identifies the optimal CNN model.The proposed CNN model efficiently predicts corresponding safety factors for different combined loadings under various soil random fields,achieving similar accuracy to the traditional time-consuming random finite element.Specifically,the coefficient of correlation exceeds 0.93 and the mean relative error is less than 2.8%for the variation of the horizontal scales of fluctuation under different combined loadings.The relative error of the predicted F_(s) value is less than 3.00%given three failure probabilities considering the variation of the vertical scales of fluctuations.These results demonstrate satisfactory prediction performance of the proposed CNN model.展开更多
Organic electrochemical transistors(OECTs)have garnered significant attention as artificial synapses due to their ability to emulate synaptic functionalities.While previous research has predominantly focused on modula...Organic electrochemical transistors(OECTs)have garnered significant attention as artificial synapses due to their ability to emulate synaptic functionalities.While previous research has predominantly focused on modulating the physical properties of the channel materials to enhance synaptic performance,the role of ion dynamics in influencing device characteristics remains underexplored.Effective regulation of ion dynamics is crucial for improving state retention and achieving long-term plasticity(LTP)in these devices.In this study,we propose a strategy to modulate the interactions between polymer semiconductors and ions in solid-electrolyte-based artificial synapses.Our findings indicate that the interplay between semiconductors and doping counterions significantly influences ion transport dynamics,thereby affecting the electrochemical doping and dedoping pro-cesses in OECTs.Notably,by suppressing the dedoping process,we achieved enhanced synaptic performances,with devices retaining 64%of the peak current after a retention time of 1000 s.Through the judicious selection of anions and optimization of their interactions with polymer semiconductors,we effectively controlled the dedoping process in OECTs,leading to improved state retention.These insights provide a novel perspective on tuning ion-polymer semiconductor interactions for the development of high-performance synaptic devices,advancing neuromorphic computing applications.展开更多
The wind environment around tall buildings in a central business district(CBD)was numerically investigated.The district covers an area of-^4.0 km2 and features a high density of tall buildings.In this study,only build...The wind environment around tall buildings in a central business district(CBD)was numerically investigated.The district covers an area of-^4.0 km2 and features a high density of tall buildings.In this study,only buildings taller than 20 m were considered,resulting in 173 tall buildings in the analysis.The numerical investigation was realized using the commercial computational fluid dynamics code FLUENT with the realizable A-6:turbulence model.Special efforts were made to maintain inflow boundary conditions throughout the computational domain.The reliability of the numerical method was validated using results from an experimental investigation conducted in the core area of the CBD(〜1.5 km2).Experimental and numerical investigations of wind speed ratios at the center of the three tallest buildings in the CBD agree within an uncertainty factor of 2.0.Both the experimental and numerical results show that wind speed ratios in the wind field with exposure category D are higher than those from the wind field with exposure category B.Based on the above validation work,the wind environment around tall buildings in the whole CBD was then investigated by numerical simulation.Common flow phenomena and patterns,such as stagnation points,shielding effects,separation flow,and channeling flow,were identified around the tall buildings.The pedestrianlevel wind environment around tall buildings in the CBD was further evaluated using nearby meteorological wind data.The evaluation results show that some pedestrian activities,such as sitting at the center of the three tallest buildings,are unadvisable when the wind blows from the south-east.展开更多
Infrared(IR)electrochromic devices,capable of dynamically controlling thermal radiation,hold promising applications in adaptive camouflage.However,the strong microwave reflective properties inherent in the device’s e...Infrared(IR)electrochromic devices,capable of dynamically controlling thermal radiation,hold promising applications in adaptive camouflage.However,the strong microwave reflective properties inherent in the device’s electrodes present a significant challenge,rendering them susceptible to radar detection and weakening their camouflage effect.Inspired by the remarkable electromagnetic control capabilities of metamaterials,the integration of frequency selective surfaces into IR electrochromic devices is proposed to address this multispectral compatibility challenge.The designed integrated metadevices simultaneously exhibit large and reversible IR emissivity tunability(Δε≥0.55 at 3–5μm,Δε≥0.5 at 7.5–13μm)and wideband microwave absorption(reflection loss≤-10 dB at 8.5–18 GHz).Furthermore,the monolithic integrated design of the shared barium fluoride substrate offers a simple device architecture,while careful design considerations mitigate coupling between IR electrochromism and microwave wideband absorption.This work introduces opportunities for the development of multispectral adaptive camouflage systems,offering potential advancements in concealment technology.展开更多
基金support of the National Natural Science Foundation of China(Grant No.42377140)the Research Project of Shanghai Investigation,Design&Research Institute Co.,Ltd.(Contract No.2022QT(12)-005(YF)).
文摘Skirted foundations are usually used in marine engineering.More researches revealed that the variations in soil undrained shear strength considerably influence the assessing performance of the bearing capacity of skirted foundations.This study proposes two machine learning-based methods to predict safety factors(F_(s))of skirted foundations under combined loadings.By comparing the prediction performance of models based on Convolutional Neural Networks(CNN)and Gaussian Process Regression,this study investigates the effect of input size of soil random field on prediction accuracy and identifies the optimal CNN model.The proposed CNN model efficiently predicts corresponding safety factors for different combined loadings under various soil random fields,achieving similar accuracy to the traditional time-consuming random finite element.Specifically,the coefficient of correlation exceeds 0.93 and the mean relative error is less than 2.8%for the variation of the horizontal scales of fluctuation under different combined loadings.The relative error of the predicted F_(s) value is less than 3.00%given three failure probabilities considering the variation of the vertical scales of fluctuations.These results demonstrate satisfactory prediction performance of the proposed CNN model.
基金supported by the Hunan Provincial Natural Science Foundation of China(2022JJ40547 and 2024JJ5031)the University of Defense Technology Research Project(ZK22-15)the National Natural Science Foundation of China(61871060 and 51201022).
文摘Organic electrochemical transistors(OECTs)have garnered significant attention as artificial synapses due to their ability to emulate synaptic functionalities.While previous research has predominantly focused on modulating the physical properties of the channel materials to enhance synaptic performance,the role of ion dynamics in influencing device characteristics remains underexplored.Effective regulation of ion dynamics is crucial for improving state retention and achieving long-term plasticity(LTP)in these devices.In this study,we propose a strategy to modulate the interactions between polymer semiconductors and ions in solid-electrolyte-based artificial synapses.Our findings indicate that the interplay between semiconductors and doping counterions significantly influences ion transport dynamics,thereby affecting the electrochemical doping and dedoping pro-cesses in OECTs.Notably,by suppressing the dedoping process,we achieved enhanced synaptic performances,with devices retaining 64%of the peak current after a retention time of 1000 s.Through the judicious selection of anions and optimization of their interactions with polymer semiconductors,we effectively controlled the dedoping process in OECTs,leading to improved state retention.These insights provide a novel perspective on tuning ion-polymer semiconductor interactions for the development of high-performance synaptic devices,advancing neuromorphic computing applications.
基金This research was supported by the Ministry of Science and Technology of the People’s Republic of China(Grant Nos.2015CB452806 and 2018YFB1501104)the National Natural Science Foundation of China(Grant No.51408196)+1 种基金the Natural Science Foundation of Shanghai(Grant No.19ZR1469200).Further support was provided by the State Key Laboratory for Disaster Reduction in Civil Engineering(No.SLDRCE15-A-04)the Study on the Wind Characteristics Caused by Typhoons Considering Offshore Wind Farm Safety along Fujian Province(No.2016FD(8)-008).The authors are indebted to the anonymous reviewers who provided valuable suggestions that improved the manuscript,particularly scientific aspects.
文摘The wind environment around tall buildings in a central business district(CBD)was numerically investigated.The district covers an area of-^4.0 km2 and features a high density of tall buildings.In this study,only buildings taller than 20 m were considered,resulting in 173 tall buildings in the analysis.The numerical investigation was realized using the commercial computational fluid dynamics code FLUENT with the realizable A-6:turbulence model.Special efforts were made to maintain inflow boundary conditions throughout the computational domain.The reliability of the numerical method was validated using results from an experimental investigation conducted in the core area of the CBD(〜1.5 km2).Experimental and numerical investigations of wind speed ratios at the center of the three tallest buildings in the CBD agree within an uncertainty factor of 2.0.Both the experimental and numerical results show that wind speed ratios in the wind field with exposure category D are higher than those from the wind field with exposure category B.Based on the above validation work,the wind environment around tall buildings in the whole CBD was then investigated by numerical simulation.Common flow phenomena and patterns,such as stagnation points,shielding effects,separation flow,and channeling flow,were identified around the tall buildings.The pedestrianlevel wind environment around tall buildings in the CBD was further evaluated using nearby meteorological wind data.The evaluation results show that some pedestrian activities,such as sitting at the center of the three tallest buildings,are unadvisable when the wind blows from the south-east.
基金National Natural Science Foundation of China(52073303)Natural Science Foundation of Hunan Province(2021JJ10049)。
文摘Infrared(IR)electrochromic devices,capable of dynamically controlling thermal radiation,hold promising applications in adaptive camouflage.However,the strong microwave reflective properties inherent in the device’s electrodes present a significant challenge,rendering them susceptible to radar detection and weakening their camouflage effect.Inspired by the remarkable electromagnetic control capabilities of metamaterials,the integration of frequency selective surfaces into IR electrochromic devices is proposed to address this multispectral compatibility challenge.The designed integrated metadevices simultaneously exhibit large and reversible IR emissivity tunability(Δε≥0.55 at 3–5μm,Δε≥0.5 at 7.5–13μm)and wideband microwave absorption(reflection loss≤-10 dB at 8.5–18 GHz).Furthermore,the monolithic integrated design of the shared barium fluoride substrate offers a simple device architecture,while careful design considerations mitigate coupling between IR electrochromism and microwave wideband absorption.This work introduces opportunities for the development of multispectral adaptive camouflage systems,offering potential advancements in concealment technology.
