This paper investigates extended state observer design problem for autonomous maritime transportation vehicles consisting of multiple unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs)via the cooperatio...This paper investigates extended state observer design problem for autonomous maritime transportation vehicles consisting of multiple unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs)via the cooperation–competition network.Through two coordinate transformations,the dynamic model of UAVs and USVs is transformed into a standard secondorder heterogeneous multi-agent system in unified earth-fixed frame.In order to recover the unavailable velocities,unpredictable fault,total disturbance as well as to estimate the heterogeneous match/unmatched nonlinearities,neural network(NN)is incorporated into the design process of the modified distributed extended state observer(MESO).Based on the Lyapunov stability analysis,it is proved that all the error signals are uniformly ultimately bounded(UUB)and the bounds could be arbitrarily small by choosing appropriate parameters.Simulation results verify the effectiveness of the proposed method.展开更多
Nitrides MAX have attracted ever-growing interest owing to its unique metallic and ceramic characteristics and properties.Here,we report on the synthesis of highly purified Ti_(2)AlN and Ti_(4)AlN_(3) powders from Ti,...Nitrides MAX have attracted ever-growing interest owing to its unique metallic and ceramic characteristics and properties.Here,we report on the synthesis of highly purified Ti_(2)AlN and Ti_(4)AlN_(3) powders from Ti,Al and TiN powders by a facile atmosphere sintering method.The obtained nitrides show highly pure phase and excellent layered structure.Except for the composition difference of raw materials,both the nitrides can be sintered and obtained by same sintering temperature and holding time,which thus makes less processing time and less usage of synthesis parameters as compared to previously synthesis methods.To our knowledge,present work is one of the few reports on synthesis of Ti_(4)AlN_(3) and Ti_(2)AlN using atmosphere sintering method.Furthermore,the lattice changes of the layered structure of Ti_(2)AlX(X/C=N)were studied by changing the composition of X position from the synthesis of Ti_(2)AlCN and Ti_(2)AlC,and the optimal formulation and synthesis mechanism of Ti_(4)AlN_(3) were also studied.展开更多
In the textile industry,it is always the case that cotton products are constitutive of many types of foreign fibers which affect the overall quality of cotton products.As the foundation of the foreign fiber automated ...In the textile industry,it is always the case that cotton products are constitutive of many types of foreign fibers which affect the overall quality of cotton products.As the foundation of the foreign fiber automated inspection,image process exerts a critical impact on the process of foreign fiber identification.This paper presents a new approach for the fast processing of foreign fiber images.This approach includes five main steps,image block,image predecision,image background extraction,image enhancement and segmentation,and image connection.At first,the captured color images were transformed into gray-scale images;followed by the inversion of gray-scale of the transformed images;then the whole image was divided into several blocks.Thereafter,the subsequent step is to judge which image block contains the target foreign fiber image through image pre-decision.Then we segment the image block via OSTU which possibly contains target images after background eradication and image strengthening.Finally,we connect those relevant segmented image blocks to get an intact and clear foreign fiber target image.The experimental result shows that this method of segmentation has the advantage of accuracy and speed over the other segmentation methods.On the other hand,this method also connects the target image that produce fractures therefore getting an intact and clear foreign fiber target image.展开更多
Interfacial water evaporation through solar heating with photothermal materials is a promising strategy for seawater desalination and wastewater purification.Tightly packed 2D membranes with high reflection losses and...Interfacial water evaporation through solar heating with photothermal materials is a promising strategy for seawater desalination and wastewater purification.Tightly packed 2D membranes with high reflection losses and limited vapor escape channels result in a low evaporation rate.In this work,3D MXene architecture was fabricated by dropping the delaminated Ti_(3)C_(2)(d-Ti_(3)C_(2))nanosheets onto the carbonized melamine foam(CMF)framework.Owing to the macroporous 3D architecture,more effective broadband solar absorption and vapor escaping were achieved.As a result,the 3D CMF@d-Ti_(3)C_(2)-based evaporator delivers a water evaporation rate of 1.60 kg/m2·h with a solar-to-vapor conversion efficiency of up to 84.6%.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62333011 and 62020106003the Natural Science Foundation of Jiangsu Province of China under Grant No.BK20222012+1 种基金the Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant No.KYCX220369the China Scholarship Council under Grant No.202206830103.
文摘This paper investigates extended state observer design problem for autonomous maritime transportation vehicles consisting of multiple unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs)via the cooperation–competition network.Through two coordinate transformations,the dynamic model of UAVs and USVs is transformed into a standard secondorder heterogeneous multi-agent system in unified earth-fixed frame.In order to recover the unavailable velocities,unpredictable fault,total disturbance as well as to estimate the heterogeneous match/unmatched nonlinearities,neural network(NN)is incorporated into the design process of the modified distributed extended state observer(MESO).Based on the Lyapunov stability analysis,it is proved that all the error signals are uniformly ultimately bounded(UUB)and the bounds could be arbitrarily small by choosing appropriate parameters.Simulation results verify the effectiveness of the proposed method.
基金This work was supported by the National Natural Science Foundation of China(61774122)the Science and Technol-ogy Developing Project of Shaanxi Province(2015KW-001)the 111 Project of China(B14040).
文摘Nitrides MAX have attracted ever-growing interest owing to its unique metallic and ceramic characteristics and properties.Here,we report on the synthesis of highly purified Ti_(2)AlN and Ti_(4)AlN_(3) powders from Ti,Al and TiN powders by a facile atmosphere sintering method.The obtained nitrides show highly pure phase and excellent layered structure.Except for the composition difference of raw materials,both the nitrides can be sintered and obtained by same sintering temperature and holding time,which thus makes less processing time and less usage of synthesis parameters as compared to previously synthesis methods.To our knowledge,present work is one of the few reports on synthesis of Ti_(4)AlN_(3) and Ti_(2)AlN using atmosphere sintering method.Furthermore,the lattice changes of the layered structure of Ti_(2)AlX(X/C=N)were studied by changing the composition of X position from the synthesis of Ti_(2)AlCN and Ti_(2)AlC,and the optimal formulation and synthesis mechanism of Ti_(4)AlN_(3) were also studied.
基金The authors thank National Natural Science Foundation of China(30971693,61170039)Ministry of Education of People’s Republic of China(NCET-09-0731)+2 种基金Hebei Education Department(Q2012063)Hebei University(2010-207)Key Laboratory of Modern Precision Agriculture System Integration Research,Ministry of Education(X11-01),for their financial support.
文摘In the textile industry,it is always the case that cotton products are constitutive of many types of foreign fibers which affect the overall quality of cotton products.As the foundation of the foreign fiber automated inspection,image process exerts a critical impact on the process of foreign fiber identification.This paper presents a new approach for the fast processing of foreign fiber images.This approach includes five main steps,image block,image predecision,image background extraction,image enhancement and segmentation,and image connection.At first,the captured color images were transformed into gray-scale images;followed by the inversion of gray-scale of the transformed images;then the whole image was divided into several blocks.Thereafter,the subsequent step is to judge which image block contains the target foreign fiber image through image pre-decision.Then we segment the image block via OSTU which possibly contains target images after background eradication and image strengthening.Finally,we connect those relevant segmented image blocks to get an intact and clear foreign fiber target image.The experimental result shows that this method of segmentation has the advantage of accuracy and speed over the other segmentation methods.On the other hand,this method also connects the target image that produce fractures therefore getting an intact and clear foreign fiber target image.
基金the National Natural Science Foundation of China(Grant No.61774122).
文摘Interfacial water evaporation through solar heating with photothermal materials is a promising strategy for seawater desalination and wastewater purification.Tightly packed 2D membranes with high reflection losses and limited vapor escape channels result in a low evaporation rate.In this work,3D MXene architecture was fabricated by dropping the delaminated Ti_(3)C_(2)(d-Ti_(3)C_(2))nanosheets onto the carbonized melamine foam(CMF)framework.Owing to the macroporous 3D architecture,more effective broadband solar absorption and vapor escaping were achieved.As a result,the 3D CMF@d-Ti_(3)C_(2)-based evaporator delivers a water evaporation rate of 1.60 kg/m2·h with a solar-to-vapor conversion efficiency of up to 84.6%.
