Federated Learning(FL)has become a popular training paradigm in recent years.However,stragglers are critical bottlenecks in an Internet of Things(IoT)network while training.These nodes produce stale updates to the ser...Federated Learning(FL)has become a popular training paradigm in recent years.However,stragglers are critical bottlenecks in an Internet of Things(IoT)network while training.These nodes produce stale updates to the server,which slow down the convergence.In this paper,we studied the impact of the stale updates on the global model,which is observed to be significant.To address this,we propose a weighted averaging scheme,FedStrag,that optimizes the training with stale updates.The work is focused on training a model in an IoT network that has multiple challenges,such as resource constraints,stragglers,network issues,device heterogeneity,etc.To this end,we developed a time-bounded asynchronous FL paradigm that can train a model on the continuous iflow of data in the edge-fog-cloud continuum.To test the FedStrag approach,a model is trained with multiple stragglers scenarios on both Independent and Identically Distributed(IID)and non-IID datasets on Raspberry Pis.The experiment results suggest that the FedStrag outperforms the baseline FedAvg in all possible cases.展开更多
Calcium sulfoaluminate cement(CSAC),first developed in China in the 1970 s,has received significant attention because of its expansive(or shrinkage-compensating)and rapid-hardening characteristics,low energy-intensity...Calcium sulfoaluminate cement(CSAC),first developed in China in the 1970 s,has received significant attention because of its expansive(or shrinkage-compensating)and rapid-hardening characteristics,low energy-intensity,and low carbon emissions.The production and hydration of CSAC(containing ye’elimite,belite,calcium sulfate,and minors)have been extensively studied,but aspects of its durability are not well understood.Due to its composition and intrinsic characteristics,CSAC concrete is expected to have better performance than Portland cement(PC)concrete in several aspects,including shrinkage and cracking due to restrained shrinkage,freeze-thaw damage,alkali-silica reaction,and sulfate attack.However,there is a lack of consensus among researchers regarding transport properties,resistance to carbonation,and steel corrosion protectiveness of CSAC concrete,all of which are expected to be tied to the chemical composition of CSAC and attributes of the service environments.For example,CASC concrete has poorer resistance to carbonation and chloride penetration compared with its PC counterpart,yet some studies have suggested that it protects steel rebar well from corrosion when exposed to a marine tidal zone,because of a strong self-desiccation effect.This paper presents a succinct review of studies of the durability of CSAC concrete.We suggest that more such studies should be conducted to examine the long-term performance of the material in different service environments.Special emphasis should be given to carbonation and steel rebar corrosion,so as to reveal the underlying deterioration mechanisms and establish means to improve the performance of CSAC concrete against such degradation processes.展开更多
In this paper,the superhydrophobic coatings on aluminium sur-faces were prepared by two-step(chemical etching followed by coating)and one-step(chemical etching and coating in a single step)processes using potassium hy...In this paper,the superhydrophobic coatings on aluminium sur-faces were prepared by two-step(chemical etching followed by coating)and one-step(chemical etching and coating in a single step)processes using potassium hydroxide and lauric acid.Besides,surface immersion time in solutions was varied in both processes.Wettability and surface morphologies of treated alumi-nium surfaces were characterized using contact angle measure-ment technique and scanning electron microscopy,respectively.Microstructures are formed on the treated aluminium surfaces which lead to increase in contact angle of the surface(>150°).Also on increasing immersion time,contact angle further increases due to increase in size and depth of microstructures.Additionally,these superhydrophobic coatings show excellent self-cleaning and corrosion-resistant behavior.Water jet impact,floatation on water surface,and low temperature condensation tests assert the excel-lent water-repellent nature of coatings.Further,coatings are to be found mechanically,thermally,and ultraviolet stable.Along with,these coatings are found to be excellent regeneration ability as verified experimentally.Although aforesaid both processes gener-ate durable and regenerable superhydrophobic aluminium sur-faces with excellent self-cleaning,corrosion-resistant,and water-repellent characteristics,but one-step process is proved more efficient and less time consuming than two-step process and promises to produce superhydrophobic coatings for industrial applications.展开更多
基金supported by SERB,India,through grant CRG/2021/003888financial support to UoH-IoE by MHRD,India(F11/9/2019-U3(A)).
文摘Federated Learning(FL)has become a popular training paradigm in recent years.However,stragglers are critical bottlenecks in an Internet of Things(IoT)network while training.These nodes produce stale updates to the server,which slow down the convergence.In this paper,we studied the impact of the stale updates on the global model,which is observed to be significant.To address this,we propose a weighted averaging scheme,FedStrag,that optimizes the training with stale updates.The work is focused on training a model in an IoT network that has multiple challenges,such as resource constraints,stragglers,network issues,device heterogeneity,etc.To this end,we developed a time-bounded asynchronous FL paradigm that can train a model on the continuous iflow of data in the edge-fog-cloud continuum.To test the FedStrag approach,a model is trained with multiple stragglers scenarios on both Independent and Identically Distributed(IID)and non-IID datasets on Raspberry Pis.The experiment results suggest that the FedStrag outperforms the baseline FedAvg in all possible cases.
基金the National Science Foundation of the United States(Nos.1932690 and 1761697)。
文摘Calcium sulfoaluminate cement(CSAC),first developed in China in the 1970 s,has received significant attention because of its expansive(or shrinkage-compensating)and rapid-hardening characteristics,low energy-intensity,and low carbon emissions.The production and hydration of CSAC(containing ye’elimite,belite,calcium sulfate,and minors)have been extensively studied,but aspects of its durability are not well understood.Due to its composition and intrinsic characteristics,CSAC concrete is expected to have better performance than Portland cement(PC)concrete in several aspects,including shrinkage and cracking due to restrained shrinkage,freeze-thaw damage,alkali-silica reaction,and sulfate attack.However,there is a lack of consensus among researchers regarding transport properties,resistance to carbonation,and steel corrosion protectiveness of CSAC concrete,all of which are expected to be tied to the chemical composition of CSAC and attributes of the service environments.For example,CASC concrete has poorer resistance to carbonation and chloride penetration compared with its PC counterpart,yet some studies have suggested that it protects steel rebar well from corrosion when exposed to a marine tidal zone,because of a strong self-desiccation effect.This paper presents a succinct review of studies of the durability of CSAC concrete.We suggest that more such studies should be conducted to examine the long-term performance of the material in different service environments.Special emphasis should be given to carbonation and steel rebar corrosion,so as to reveal the underlying deterioration mechanisms and establish means to improve the performance of CSAC concrete against such degradation processes.
基金The authors are indebted to the Science&Engineering Research Board,Department of Science and Technology,Government of India(Grant No.YSS/2015/000036)for financial support.
文摘In this paper,the superhydrophobic coatings on aluminium sur-faces were prepared by two-step(chemical etching followed by coating)and one-step(chemical etching and coating in a single step)processes using potassium hydroxide and lauric acid.Besides,surface immersion time in solutions was varied in both processes.Wettability and surface morphologies of treated alumi-nium surfaces were characterized using contact angle measure-ment technique and scanning electron microscopy,respectively.Microstructures are formed on the treated aluminium surfaces which lead to increase in contact angle of the surface(>150°).Also on increasing immersion time,contact angle further increases due to increase in size and depth of microstructures.Additionally,these superhydrophobic coatings show excellent self-cleaning and corrosion-resistant behavior.Water jet impact,floatation on water surface,and low temperature condensation tests assert the excel-lent water-repellent nature of coatings.Further,coatings are to be found mechanically,thermally,and ultraviolet stable.Along with,these coatings are found to be excellent regeneration ability as verified experimentally.Although aforesaid both processes gener-ate durable and regenerable superhydrophobic aluminium sur-faces with excellent self-cleaning,corrosion-resistant,and water-repellent characteristics,but one-step process is proved more efficient and less time consuming than two-step process and promises to produce superhydrophobic coatings for industrial applications.
