Effective data communication is a crucial aspect of the Social Internet of Things(SIoT)and continues to be a significant research focus.This paper proposes a data forwarding algorithm based on Multidimensional Social ...Effective data communication is a crucial aspect of the Social Internet of Things(SIoT)and continues to be a significant research focus.This paper proposes a data forwarding algorithm based on Multidimensional Social Relations(MSRR)in SIoT to solve this problem.The proposed algorithm separates message forwarding into intra-and cross-community forwarding by analyzing interest traits and social connections among nodes.Three new metrics are defined:the intensity of node social relationships,node activity,and community connectivity.Within the community,messages are sent by determining which node is most similar to the sender by weighing the strength of social connections and node activity.When a node performs cross-community forwarding,the message is forwarded to the most reasonable relay community by measuring the node activity and the connection between communities.The proposed algorithm was compared to three existing routing algorithms in simulation experiments.Results indicate that the proposed algorithmsubstantially improves message delivery efficiency while lessening network overhead and enhancing connectivity and coordination in the SIoT context.展开更多
Named Data Networking(NDN)has emerged as a promising communication paradigm,emphasizing content-centric access rather than location-based access.This model offers several advantages for Internet of Healthcare Things(I...Named Data Networking(NDN)has emerged as a promising communication paradigm,emphasizing content-centric access rather than location-based access.This model offers several advantages for Internet of Healthcare Things(IoHT)environments,including efficient content distribution,built-in security,and natural support for mobility and scalability.However,existing NDN-based IoHT systems face inefficiencies in their forwarding strategy,where identical Interest packets are forwarded across multiple nodes,causing broadcast storms,increased collisions,higher energy consumption,and delays.These issues negatively impact healthcare system performance,particularly for individuals with disabilities and chronic diseases requiring continuous monitoring.To address these challenges,we propose a Smart and Energy-Aware Forwarding(SEF)strategy based on reinforcement learning for NDN-based IoHT.The SEF strategy leverages the geographical distance and energy levels of neighboring nodes,enabling devices to make more informed forwarding decisions and optimize next-hop selection.This approach reduces broadcast storms,optimizes overall energy consumption,and extends network lifetime.The system model,which targets smart hospitals and monitoring systems for individuals with disabilities,was examined in relation to the proposed strategy.The SEF strategy was then implemented in the NS-3 simulation environment to assess its performance in healthcare scenarios.Results demonstrated that SEF significantly enhanced NDN-based IoHT performance.Specifically,it reduced energy consumption by up to 27.11%,82.23%,and 84.44%,decreased retrieval time by 20.23%,48.12%,and 51.65%,and achieved satisfaction rates that were approximately 0.69 higher than those of other strategies,even in more densely populated areas.This forwarding strategy is anticipated to substantially improve the quality and efficiency of NDN-based IoHT systems.展开更多
To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method...To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method for a class of parallel platforms with 3-RE structure after locking the actuated joints is proposed in this paper.Given that the angle between specific joint axes of limbs remains constant,a set of geometric constraints for the forward kinematics of parallel mechanisms(PM)are determined.After translating unit direction vectors of these joint axes to the common starting point,the geometric constraints of the angle between the vectors are transformed into the distances between the endpoints of the vectors,making them easier to handle.Under the framework of CGA,the positions of key points that determine the position and orientation of the moving platform can be intuitively determined by the intersection,division,and duality of basic geometric entities.By employing the tangent half-angle substitution,the forward kinematic analysis of the parallel mechanisms leads to a high-order univariate polynomial equation without the need for any complex algebraic elimination operations.After solving this equation and back substitution,the position and pose of the MP can be obtained indirectly.A numerical case is utilized to confirm the effectiveness of the proposed method.展开更多
This study presents a novel analytical algorithm for solving the forward position problem of a triangular platform Stewart-type parallel robot(STPR).By introducing a virtual chain and leveraging tetrahedral geometric ...This study presents a novel analytical algorithm for solving the forward position problem of a triangular platform Stewart-type parallel robot(STPR).By introducing a virtual chain and leveraging tetrahedral geometric principles,the proposed method derives analytical solutions for the position and orientation of the moving platform.The algorithm systematically addresses the nonlinearity inherent in the kinematic equations of parallel mechanisms,providing explicit expressions for the coordinates of key moving attachment points.Furthermore,the methodology is extended to general triangular platform STPRs with non-coplanar fixed attachments.Numerical validation through virtual experiments confirms the accuracy of the solutions,demonstrating that the mechanism admits eight distinct configurations for a given set of limb lengths.The results align with established kinematic principles and offer a computationally efficient alternative to iterative analytical approaches,contributing to the advancement of precision control in parallel robotic systems.展开更多
With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object si...With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object significant challenges have been presented in accurately segmenting melanomas in dermoscopic images due to the objects that could interfere human observations,such as bubbles and scales.To address these challenges,we propose a dual U-Net network framework for skin melanoma segmentation.In our proposed architecture,we introduce several innovative components that aim to enhance the performance and capabilities of the traditional U-Net.First,we establish a novel framework that links two simplified U-Nets,enabling more comprehensive information exchange and feature integration throughout the network.Second,after cascading the second U-Net,we introduce a skip connection between the decoder and encoder networks,and incorporate a modified receptive field block(MRFB),which is designed to capture multi-scale spatial information.Third,to further enhance the feature representation capabilities,we add a multi-path convolution block attention module(MCBAM)to the first two layers of the first U-Net encoding,and integrate a new squeeze-and-excitation(SE)mechanism with residual connections in the second U-Net.To illustrate the performance of our proposed model,we conducted comprehensive experiments on widely recognized skin datasets.On the ISIC-2017 dataset,the IoU value of our proposed model increased from 0.6406 to 0.6819 and the Dice coefficient increased from 0.7625 to 0.8023.On the ISIC-2018 dataset,the IoU value of proposed model also improved from 0.7138 to 0.7709,while the Dice coefficient increased from 0.8285 to 0.8665.Furthermore,the generalization experiments conducted on the jaw cyst dataset from Quzhou People’s Hospital further verified the outstanding segmentation performance of the proposed model.These findings collectively affirm the potential of our approach as a valuable tool in supporting clinical decision-making in the field of skin cancer detection,as well as advancing research in medical image analysis.展开更多
We propose a novel workflow for fast forward modeling of well logs in axially symmetric 2D models of the nearwellbore environment.The approach integrates the finite element method with deep residual neural networks to...We propose a novel workflow for fast forward modeling of well logs in axially symmetric 2D models of the nearwellbore environment.The approach integrates the finite element method with deep residual neural networks to achieve exceptional computational efficiency and accuracy.The workflow is demonstrated through the modeling of wireline electromagnetic propagation resistivity logs,where the measured responses exhibit a highly nonlinear relationship with formation properties.The motivation for this research is the need for advanced modeling al-gorithms that are fast enough for use in modern quantitative interpretation tools,where thousands of simulations may be required in iterative inversion processes.The proposed algorithm achieves a remarkable enhancement in performance,being up to 3000 times faster than the finite element method alone when utilizing a GPU.While still ensuring high accuracy,this makes it well-suited for practical applications when reliable payzone assessment is needed in complex environmental scenarios.Furthermore,the algorithm’s efficiency positions it as a promising tool for stochastic Bayesian inversion,facilitating reliable uncertainty quantification in subsurface property estimation.展开更多
Seawater electrolysis for hydrogen production faces inherent challenges, including side reactions, corrosion, and scaling, stemming from the intricate composition of seawater. In response, researchers have turned to c...Seawater electrolysis for hydrogen production faces inherent challenges, including side reactions, corrosion, and scaling, stemming from the intricate composition of seawater. In response, researchers have turned to continuous water splitting using forward osmosis(FO)-driven seawater desalination. However, the necessity of a neutral electrolyte hampers this strategy due to the limited current density and scarcity of precious metals. Herein, this study applies alkali-durable FO membranes to enable self-sustaining seawater splitting, which can selectively withdraw water molecules, from seawater, via concentration gradient. The membranes demonstrates outstanding perm-selectivity of water/ions(~5830 mol mol^(-1)) during month-long alkaline resistance tests, preventing electrolyte leaching(>97% OHàretention) while maintaining ~95%water balance(V_(FO)= V_(electrolysis)) via preserved concentration gradient for consistent forward-osmosis influx of water molecules. With the consistent electrolyte environment protected by the polyamide FO membranes, the Ni Fe-Ar-P catalyst exhibits promising performance: a sustain current density of 360 m A cmà2maintained at the cell voltage of 2.10 V and 2.15 V for 360 h in the offshore seawater, preventing Cl/Br corrosion(98% rejection) and Mg/Ca passivation(99.6% rejection). This research marks a significant advancement towards efficient and durable seawater-based hydrogen production.展开更多
A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering(FSBS)in highly nonlinear fiber(HNLF)with high sensitivity and high accuracy is proposed and demonstrated in thi...A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering(FSBS)in highly nonlinear fiber(HNLF)with high sensitivity and high accuracy is proposed and demonstrated in this paper.High-order acoustic modes(HOAMs)are used to achieve individual or simultaneous measurement of the two parameters.Transverse acoustic waves(TAWs)involved in the FSBS process can efficiently sense the mechanical or environmental changes outside the fiber cladding,which will be reflected in a linear shift of the acoustic resonance frequency.By analyzing the frequencies of specific scattering peaks,the temperature and acoustic impedance outside the fiber cladding can be obtained simultaneously.The highest measured temperature and acoustic impedance sensitivities are 184.93 k Hz/℃and444.56 k Hz/MRayl,and the measurement accuracies are 0.09℃and 0.009 MRayl,respectively,which are both at desirable levels.We believe this work can provide potential application solutions for sensing fields involving temperature or acoustic impedance measurements.展开更多
On the morning of May 31st,the parallel forum"Ecological Actions to Carry Forward the Shared Values of Mankind,"as part of the 4th Dialogue on Exchanges and Mutual Learning among Civilisations,was held in Du...On the morning of May 31st,the parallel forum"Ecological Actions to Carry Forward the Shared Values of Mankind,"as part of the 4th Dialogue on Exchanges and Mutual Learning among Civilisations,was held in Dunhuang.More than 50 experts and scholars from different countries,including China,Kenya and Japan,engaged in indepth discussions on the theme.展开更多
AVO forward modeling is based on two-phase medium theory and is considered an effective method for describing reservoir rocks and fluids. However, the method depends on the input matrix mineral bulk modulus and the ra...AVO forward modeling is based on two-phase medium theory and is considered an effective method for describing reservoir rocks and fluids. However, the method depends on the input matrix mineral bulk modulus and the rationality of the two-phase medium model. We used the matrix mineral bulk modulus inversion method and multiple constraints to obtain a two-phase medium model with physical meaning. The proposed method guarantees the reliability of the obtained AVO characteristicsin two-phase media. By the comparative analysis of different lithology of the core sample, the advantages and accuracy of the inversion method can be illustrated. Also, the inversion method can be applied in LH area, and the AVO characteristics can be obtained when the porosity, fluid saturation, and other important lithology parameters are changed. In particular, the reflection coefficient amplitude difference between the fast P wave and S wave as a function of porosity at the same incidence angle, and the difference in the incidence angle threshold can be used to decipher porosity.展开更多
This study examined the spatio-temporal trajectories of the international freight forwarding service(IFFS) in the Yangtze River Delta(YRD) and explored the driving mechanisms of the service. Based on a bipartite netwo...This study examined the spatio-temporal trajectories of the international freight forwarding service(IFFS) in the Yangtze River Delta(YRD) and explored the driving mechanisms of the service. Based on a bipartite network projection from an IFFS firm-city data source, we mapped three IFFS networks in the YRD in 2005, 2010, and 2015. A range of statistical indicators were used to explore changes in the spatial patterns of the three networks. The underlying influence of marketization, globalization, decentralization, and integration was then explored. It was found that the connections between Shanghai and other nodal cities formed the backbones of these networks. The effects of a city's administrative level and provincial administrative borders were generally obvious. We found several specific spatial patterns associated with IFFS. For example, the four non-administrative centers of Ningbo, Suzhou, Lianyungang, and Nantong were the most connected cities and played the role of gateway cities. Furthermore, remarkable regional equalities were found regarding a city's IFFS network provision, with notable examples in the weakly connected areas of northern Jiangsu and southwestern Zhejiang. Finally, an analysis of the driving mechanisms demonstrated that IFFS network changes were highly sensitive to the influences of marketization and globalization, while regional integration played a lesser role in driving changes in IFFS networks.展开更多
We show that an aggregated Interest in Named Data Networking (NDN) may fail to retrieve desired data since the Interest previously sent upstream for the same content is judged as a duplicate one and then dropped by an...We show that an aggregated Interest in Named Data Networking (NDN) may fail to retrieve desired data since the Interest previously sent upstream for the same content is judged as a duplicate one and then dropped by an upstream node due to its multipath forwarding. Furthermore, we propose NDRUDAF, a NACK based mechanism that enhances the Interest forwarding and enables Detection and fast Recovery from such Unanticipated Data Access Failure. In the NDN enhanced with NDRUDAF, the router that aggregates the Interest detects such unanticipated data access failure based on a negative acknowledgement from the upstream node that judges the Interest as a duplicate one. Then the router retransmits the Interest as soon as possible on behalf of the requester whose Interest is aggregated to fast recover from the data access failure. We qualitatively and quantitatively analyze the performance of the NDN enhanced with our proposed NDRUDAF and compare it with that of the present NDN. Our experimental results validate that NDRUDAF improves the system performance in case of such unanticipated data access failure in terms of data access delay and network resource utilization efficiency at routers.展开更多
It is well known that today's inter-domain routing protocol, Border Gateway Protocol (BGP), converges slowly during network failures. Due to the distribution nature of Internet routing decisions and the rate-limit...It is well known that today's inter-domain routing protocol, Border Gateway Protocol (BGP), converges slowly during network failures. Due to the distribution nature of Internet routing decisions and the rate-limiting timer Minimum Route Advertisement Interval (MRAI) of BGP, unavoidable convergence latency is introduced in reaction to network changes. During the period of convergence temporarily routing table inconsistencies cause short-term routing blackholes and loops which result in widespread temporary burst packet loss. In this paper, we present ROute-Free Forwarding (ROFF) - a novel technique for packet delivering continuously during periods of convergence. With slightly modifications on IP packet header and BGP, route loops and blackholes can be avoided. Our preliminary evaluation demonstrates that ROFF succeeds in reducing the number of Autonomous Systems (ASes) which experience burst packet loss and the duration of packet loss.展开更多
The security problems of wireless sensor networks (WSN) have attracted people’s wide attention. In this paper, after we have summarized the existing security problems and solutions in WSN, we find that the insider at...The security problems of wireless sensor networks (WSN) have attracted people’s wide attention. In this paper, after we have summarized the existing security problems and solutions in WSN, we find that the insider attack to WSN is hard to solve. Insider attack is different from outsider attack, because it can’t be solved by the traditional encryption and message authentication. Therefore, a reliable secure routing protocol should be proposed in order to defense the insider attack. In this paper, we focus on insider selective forwarding attack. The existing detection mechanisms, such as watchdog, multipath retreat, neighbor-based monitoring and so on, have both advantages and disadvantages. According to their characteristics, we proposed a secure routing protocol based on monitor node and trust mechanism. The reputation value is made up with packet forwarding rate and node’s residual energy. So this detection and routing mechanism is universal because it can take account of both the safety and lifetime of network. Finally, we use OPNET simulation to verify the performance of our algorithm.展开更多
The Space-Air-Ground Integrated Network(SAGIN) realizes the integration of space, air,and ground networks, obtaining the global communication coverage.Software-Defined Networking(SDN) architecture in SAGIN has become ...The Space-Air-Ground Integrated Network(SAGIN) realizes the integration of space, air,and ground networks, obtaining the global communication coverage.Software-Defined Networking(SDN) architecture in SAGIN has become a promising solution to guarantee the Quality of Service(QoS).However, the current routing algorithms mainly focus on the QoS of the service, rarely considering the security requirement of flow. To realize the secure transmission of flows in SAGIN, we propose an intelligent flow forwarding scheme with endogenous security based on Mimic Defense(ESMD-Flow). In this scheme, SDN controller will evaluate the reliability of nodes and links, isolate malicious nodes based on the reliability evaluation value, and adapt multipath routing strategy to ensure that flows are always forwarded along the most reliable multiple paths. In addition, in order to meet the security requirement of flows, we introduce the programming data plane to design a multiprotocol forwarding strategy for realizing the multiprotocol dynamic forwarding of flows. ESMD-Flow can reduce the network attack surface and improve the secure transmission capability of flows by implementing multipath routing and multi-protocol hybrid forwarding mechanism. The extensive simulations demonstrate that ESMD-Flow can significantly improve the average path reliability for routing and increase the difficulty of network eavesdropping while improving the network throughput and reducing the average packet delay.展开更多
Recent advances in broadband technology have caused forwarding engines to handle pack- ets with over 10 gigabit per second. In this paper, we present a high-speed forwarding pipeline which can finish all of the routin...Recent advances in broadband technology have caused forwarding engines to handle pack- ets with over 10 gigabit per second. In this paper, we present a high-speed forwarding pipeline which can finish all of the routing and forwarding tasks in the way of pipelining. We also establish the analysis model of the pipeline with which one can evaluate some key performance parameters of the forwarding engine such as forwarding rate and forwarding delay. We find that the pipeline is of good scalability and can forward unicast packets up to the speed of 40Gbit/s.展开更多
In this paper, the forwarding objective and mobility law of nodes in opportunistic networks are first investigated to establish a mathematical model for further analysis, then a gradually accelerated data forwarding a...In this paper, the forwarding objective and mobility law of nodes in opportunistic networks are first investigated to establish a mathematical model for further analysis, then a gradually accelerated data forwarding algorithm is proposed. In this algorithm, according to the distance between data carriers （nodes） and the destination, some intermediate nodes are selected to relay the data. Especially, the forwarded copies can be increased when the delay reaches a threshold, to guarantee the required delivery ratio. The simulation results show that the proposed algorithm can effectively reduce the storage occupancies of nodes and forwarding delay, and guarantee the delivery ratio simultaneously.展开更多
In wireless sensor networks, topology control plays an important role for data forwarding efficiency in the data gathering applications. In this paper, we present a novel topology control and data forwarding mechanism...In wireless sensor networks, topology control plays an important role for data forwarding efficiency in the data gathering applications. In this paper, we present a novel topology control and data forwarding mechanism called REMUDA, which is designed for a practical indoor parking lot management system. REMUDA forms a tree-based hierarchical network topology which brings as many nodes as possible to be leaf nodes and constructs a virtual cluster structure. Meanwhile, it takes the reliability, stability and path length into account in the tree construction process. Through an experiment in a network of 30 real sensor nodes, we evaluate the performance of REMUDA and compare it with LEPS which is also a practical routing protocol in TinyOS. Experiment results show that REMUDA can achieve better performance than LEPS.展开更多
基金supported by the NationalNatural Science Foundation of China(61972136)the Hubei Provincial Department of Education Outstanding Youth Scientific Innovation Team Support Foundation(T201410,T2020017)+1 种基金the Natural Science Foundation of Xiaogan City(XGKJ2022010095,XGKJ2022010094)the Science and Technology Research Project of Education Department of Hubei Province(No.Q20222704).
文摘Effective data communication is a crucial aspect of the Social Internet of Things(SIoT)and continues to be a significant research focus.This paper proposes a data forwarding algorithm based on Multidimensional Social Relations(MSRR)in SIoT to solve this problem.The proposed algorithm separates message forwarding into intra-and cross-community forwarding by analyzing interest traits and social connections among nodes.Three new metrics are defined:the intensity of node social relationships,node activity,and community connectivity.Within the community,messages are sent by determining which node is most similar to the sender by weighing the strength of social connections and node activity.When a node performs cross-community forwarding,the message is forwarded to the most reasonable relay community by measuring the node activity and the connection between communities.The proposed algorithm was compared to three existing routing algorithms in simulation experiments.Results indicate that the proposed algorithmsubstantially improves message delivery efficiency while lessening network overhead and enhancing connectivity and coordination in the SIoT context.
基金funded by the King Salman Center for Disability Research through Research Group No.KSRG-2023-335.
文摘Named Data Networking(NDN)has emerged as a promising communication paradigm,emphasizing content-centric access rather than location-based access.This model offers several advantages for Internet of Healthcare Things(IoHT)environments,including efficient content distribution,built-in security,and natural support for mobility and scalability.However,existing NDN-based IoHT systems face inefficiencies in their forwarding strategy,where identical Interest packets are forwarded across multiple nodes,causing broadcast storms,increased collisions,higher energy consumption,and delays.These issues negatively impact healthcare system performance,particularly for individuals with disabilities and chronic diseases requiring continuous monitoring.To address these challenges,we propose a Smart and Energy-Aware Forwarding(SEF)strategy based on reinforcement learning for NDN-based IoHT.The SEF strategy leverages the geographical distance and energy levels of neighboring nodes,enabling devices to make more informed forwarding decisions and optimize next-hop selection.This approach reduces broadcast storms,optimizes overall energy consumption,and extends network lifetime.The system model,which targets smart hospitals and monitoring systems for individuals with disabilities,was examined in relation to the proposed strategy.The SEF strategy was then implemented in the NS-3 simulation environment to assess its performance in healthcare scenarios.Results demonstrated that SEF significantly enhanced NDN-based IoHT performance.Specifically,it reduced energy consumption by up to 27.11%,82.23%,and 84.44%,decreased retrieval time by 20.23%,48.12%,and 51.65%,and achieved satisfaction rates that were approximately 0.69 higher than those of other strategies,even in more densely populated areas.This forwarding strategy is anticipated to substantially improve the quality and efficiency of NDN-based IoHT systems.
基金Supported by National Natural Science Foundation of China (Grant No. 52175019)Beijing Municipal Natural Science Foundation of China (Grant No. L222038)+3 种基金Beijing Nova Programme Interdisciplinary Cooperation Project of China (Grant No. 20240484699)Joint Funds of Industry-University-Research of Shanghai Academy of Spaceflight Technology of China (Grant No. SAST2022-017)Beijing Municipal Key Laboratory of Space-ground Interconnection and Convergence of ChinaKey Laboratory of IoT Monitoring and Early Warning,Ministry of Emergency Management of China
文摘To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method for a class of parallel platforms with 3-RE structure after locking the actuated joints is proposed in this paper.Given that the angle between specific joint axes of limbs remains constant,a set of geometric constraints for the forward kinematics of parallel mechanisms(PM)are determined.After translating unit direction vectors of these joint axes to the common starting point,the geometric constraints of the angle between the vectors are transformed into the distances between the endpoints of the vectors,making them easier to handle.Under the framework of CGA,the positions of key points that determine the position and orientation of the moving platform can be intuitively determined by the intersection,division,and duality of basic geometric entities.By employing the tangent half-angle substitution,the forward kinematic analysis of the parallel mechanisms leads to a high-order univariate polynomial equation without the need for any complex algebraic elimination operations.After solving this equation and back substitution,the position and pose of the MP can be obtained indirectly.A numerical case is utilized to confirm the effectiveness of the proposed method.
基金supported by the Opening Project of State Key Laboratory of Mechanical Transmission for Advanced Equipment(No.SKLMT-MSKFKT202330)the National Natural Science Foundation of China(No.52575022)the Jiangsu Province Postgraduate Research&Practice Innovation Program(No.KYCX25_1403)。
文摘This study presents a novel analytical algorithm for solving the forward position problem of a triangular platform Stewart-type parallel robot(STPR).By introducing a virtual chain and leveraging tetrahedral geometric principles,the proposed method derives analytical solutions for the position and orientation of the moving platform.The algorithm systematically addresses the nonlinearity inherent in the kinematic equations of parallel mechanisms,providing explicit expressions for the coordinates of key moving attachment points.Furthermore,the methodology is extended to general triangular platform STPRs with non-coplanar fixed attachments.Numerical validation through virtual experiments confirms the accuracy of the solutions,demonstrating that the mechanism admits eight distinct configurations for a given set of limb lengths.The results align with established kinematic principles and offer a computationally efficient alternative to iterative analytical approaches,contributing to the advancement of precision control in parallel robotic systems.
基金funded by Zhejiang Basic Public Welfare Research Project,grant number LZY24E060001supported by Guangzhou Development Zone Science and Technology(2021GH10,2020GH10,2023GH02)+1 种基金the University of Macao(MYRG2022-00271-FST)the Science and Technology Development Fund(FDCT)of Macao(0032/2022/A).
文摘With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object significant challenges have been presented in accurately segmenting melanomas in dermoscopic images due to the objects that could interfere human observations,such as bubbles and scales.To address these challenges,we propose a dual U-Net network framework for skin melanoma segmentation.In our proposed architecture,we introduce several innovative components that aim to enhance the performance and capabilities of the traditional U-Net.First,we establish a novel framework that links two simplified U-Nets,enabling more comprehensive information exchange and feature integration throughout the network.Second,after cascading the second U-Net,we introduce a skip connection between the decoder and encoder networks,and incorporate a modified receptive field block(MRFB),which is designed to capture multi-scale spatial information.Third,to further enhance the feature representation capabilities,we add a multi-path convolution block attention module(MCBAM)to the first two layers of the first U-Net encoding,and integrate a new squeeze-and-excitation(SE)mechanism with residual connections in the second U-Net.To illustrate the performance of our proposed model,we conducted comprehensive experiments on widely recognized skin datasets.On the ISIC-2017 dataset,the IoU value of our proposed model increased from 0.6406 to 0.6819 and the Dice coefficient increased from 0.7625 to 0.8023.On the ISIC-2018 dataset,the IoU value of proposed model also improved from 0.7138 to 0.7709,while the Dice coefficient increased from 0.8285 to 0.8665.Furthermore,the generalization experiments conducted on the jaw cyst dataset from Quzhou People’s Hospital further verified the outstanding segmentation performance of the proposed model.These findings collectively affirm the potential of our approach as a valuable tool in supporting clinical decision-making in the field of skin cancer detection,as well as advancing research in medical image analysis.
基金financially supported by the Russian federal research project No.FWZZ-2022-0026“Innovative aspects of electro-dynamics in problems of exploration and oilfield geophysics”.
文摘We propose a novel workflow for fast forward modeling of well logs in axially symmetric 2D models of the nearwellbore environment.The approach integrates the finite element method with deep residual neural networks to achieve exceptional computational efficiency and accuracy.The workflow is demonstrated through the modeling of wireline electromagnetic propagation resistivity logs,where the measured responses exhibit a highly nonlinear relationship with formation properties.The motivation for this research is the need for advanced modeling al-gorithms that are fast enough for use in modern quantitative interpretation tools,where thousands of simulations may be required in iterative inversion processes.The proposed algorithm achieves a remarkable enhancement in performance,being up to 3000 times faster than the finite element method alone when utilizing a GPU.While still ensuring high accuracy,this makes it well-suited for practical applications when reliable payzone assessment is needed in complex environmental scenarios.Furthermore,the algorithm’s efficiency positions it as a promising tool for stochastic Bayesian inversion,facilitating reliable uncertainty quantification in subsurface property estimation.
基金funding provided by the National Key R&D Program of China (Grant No. 2021YFB3801301)National Natural Science Foundation of China (Grant Nos. 22075076, 22208097 and 22378119)Shanghai Pilot Program for Basic Research (22TQ1400100-4)。
文摘Seawater electrolysis for hydrogen production faces inherent challenges, including side reactions, corrosion, and scaling, stemming from the intricate composition of seawater. In response, researchers have turned to continuous water splitting using forward osmosis(FO)-driven seawater desalination. However, the necessity of a neutral electrolyte hampers this strategy due to the limited current density and scarcity of precious metals. Herein, this study applies alkali-durable FO membranes to enable self-sustaining seawater splitting, which can selectively withdraw water molecules, from seawater, via concentration gradient. The membranes demonstrates outstanding perm-selectivity of water/ions(~5830 mol mol^(-1)) during month-long alkaline resistance tests, preventing electrolyte leaching(>97% OHàretention) while maintaining ~95%water balance(V_(FO)= V_(electrolysis)) via preserved concentration gradient for consistent forward-osmosis influx of water molecules. With the consistent electrolyte environment protected by the polyamide FO membranes, the Ni Fe-Ar-P catalyst exhibits promising performance: a sustain current density of 360 m A cmà2maintained at the cell voltage of 2.10 V and 2.15 V for 360 h in the offshore seawater, preventing Cl/Br corrosion(98% rejection) and Mg/Ca passivation(99.6% rejection). This research marks a significant advancement towards efficient and durable seawater-based hydrogen production.
文摘A temperature and acoustic impedance simultaneous sensor based on forward stimulated Brillouin scattering(FSBS)in highly nonlinear fiber(HNLF)with high sensitivity and high accuracy is proposed and demonstrated in this paper.High-order acoustic modes(HOAMs)are used to achieve individual or simultaneous measurement of the two parameters.Transverse acoustic waves(TAWs)involved in the FSBS process can efficiently sense the mechanical or environmental changes outside the fiber cladding,which will be reflected in a linear shift of the acoustic resonance frequency.By analyzing the frequencies of specific scattering peaks,the temperature and acoustic impedance outside the fiber cladding can be obtained simultaneously.The highest measured temperature and acoustic impedance sensitivities are 184.93 k Hz/℃and444.56 k Hz/MRayl,and the measurement accuracies are 0.09℃and 0.009 MRayl,respectively,which are both at desirable levels.We believe this work can provide potential application solutions for sensing fields involving temperature or acoustic impedance measurements.
文摘On the morning of May 31st,the parallel forum"Ecological Actions to Carry Forward the Shared Values of Mankind,"as part of the 4th Dialogue on Exchanges and Mutual Learning among Civilisations,was held in Dunhuang.More than 50 experts and scholars from different countries,including China,Kenya and Japan,engaged in indepth discussions on the theme.
基金supported by the National Natural Science Foundation of China(Grant Nos.41404101,41174114,41274130,and 41404102)
文摘AVO forward modeling is based on two-phase medium theory and is considered an effective method for describing reservoir rocks and fluids. However, the method depends on the input matrix mineral bulk modulus and the rationality of the two-phase medium model. We used the matrix mineral bulk modulus inversion method and multiple constraints to obtain a two-phase medium model with physical meaning. The proposed method guarantees the reliability of the obtained AVO characteristicsin two-phase media. By the comparative analysis of different lithology of the core sample, the advantages and accuracy of the inversion method can be illustrated. Also, the inversion method can be applied in LH area, and the AVO characteristics can be obtained when the porosity, fluid saturation, and other important lithology parameters are changed. In particular, the reflection coefficient amplitude difference between the fast P wave and S wave as a function of porosity at the same incidence angle, and the difference in the incidence angle threshold can be used to decipher porosity.
基金National Natural Science Foundation of China(No.41671132,41771139)Natural Science Foundation of Jiangsu Province(No.BK20171516)
文摘This study examined the spatio-temporal trajectories of the international freight forwarding service(IFFS) in the Yangtze River Delta(YRD) and explored the driving mechanisms of the service. Based on a bipartite network projection from an IFFS firm-city data source, we mapped three IFFS networks in the YRD in 2005, 2010, and 2015. A range of statistical indicators were used to explore changes in the spatial patterns of the three networks. The underlying influence of marketization, globalization, decentralization, and integration was then explored. It was found that the connections between Shanghai and other nodal cities formed the backbones of these networks. The effects of a city's administrative level and provincial administrative borders were generally obvious. We found several specific spatial patterns associated with IFFS. For example, the four non-administrative centers of Ningbo, Suzhou, Lianyungang, and Nantong were the most connected cities and played the role of gateway cities. Furthermore, remarkable regional equalities were found regarding a city's IFFS network provision, with notable examples in the weakly connected areas of northern Jiangsu and southwestern Zhejiang. Finally, an analysis of the driving mechanisms demonstrated that IFFS network changes were highly sensitive to the influences of marketization and globalization, while regional integration played a lesser role in driving changes in IFFS networks.
基金supported in part by the National Natural Science Foundation of China (No.61602114)part by the National Key Research and Development Program of China (2017YFB0801703)+1 种基金part by the CERNET Innovation Project (NGII20170406)part by Jiangsu Provincial Key Laboratory of Network and Information Security (BM2003201)
文摘We show that an aggregated Interest in Named Data Networking (NDN) may fail to retrieve desired data since the Interest previously sent upstream for the same content is judged as a duplicate one and then dropped by an upstream node due to its multipath forwarding. Furthermore, we propose NDRUDAF, a NACK based mechanism that enhances the Interest forwarding and enables Detection and fast Recovery from such Unanticipated Data Access Failure. In the NDN enhanced with NDRUDAF, the router that aggregates the Interest detects such unanticipated data access failure based on a negative acknowledgement from the upstream node that judges the Interest as a duplicate one. Then the router retransmits the Interest as soon as possible on behalf of the requester whose Interest is aggregated to fast recover from the data access failure. We qualitatively and quantitatively analyze the performance of the NDN enhanced with our proposed NDRUDAF and compare it with that of the present NDN. Our experimental results validate that NDRUDAF improves the system performance in case of such unanticipated data access failure in terms of data access delay and network resource utilization efficiency at routers.
基金Supported by Major State Basic Research Development Program (973 Program) (No. 2007CB307102, No. 2007CB 307100)
文摘It is well known that today's inter-domain routing protocol, Border Gateway Protocol (BGP), converges slowly during network failures. Due to the distribution nature of Internet routing decisions and the rate-limiting timer Minimum Route Advertisement Interval (MRAI) of BGP, unavoidable convergence latency is introduced in reaction to network changes. During the period of convergence temporarily routing table inconsistencies cause short-term routing blackholes and loops which result in widespread temporary burst packet loss. In this paper, we present ROute-Free Forwarding (ROFF) - a novel technique for packet delivering continuously during periods of convergence. With slightly modifications on IP packet header and BGP, route loops and blackholes can be avoided. Our preliminary evaluation demonstrates that ROFF succeeds in reducing the number of Autonomous Systems (ASes) which experience burst packet loss and the duration of packet loss.
文摘The security problems of wireless sensor networks (WSN) have attracted people’s wide attention. In this paper, after we have summarized the existing security problems and solutions in WSN, we find that the insider attack to WSN is hard to solve. Insider attack is different from outsider attack, because it can’t be solved by the traditional encryption and message authentication. Therefore, a reliable secure routing protocol should be proposed in order to defense the insider attack. In this paper, we focus on insider selective forwarding attack. The existing detection mechanisms, such as watchdog, multipath retreat, neighbor-based monitoring and so on, have both advantages and disadvantages. According to their characteristics, we proposed a secure routing protocol based on monitor node and trust mechanism. The reputation value is made up with packet forwarding rate and node’s residual energy. So this detection and routing mechanism is universal because it can take account of both the safety and lifetime of network. Finally, we use OPNET simulation to verify the performance of our algorithm.
基金supported by the National Key Research and Development Program of China under Grant 2020YFB1804803the National Natural Science Foundation of China under Grant 61872382the Research and Development Program in Key Areas of Guangdong Province under Grant No.2018B010113001。
文摘The Space-Air-Ground Integrated Network(SAGIN) realizes the integration of space, air,and ground networks, obtaining the global communication coverage.Software-Defined Networking(SDN) architecture in SAGIN has become a promising solution to guarantee the Quality of Service(QoS).However, the current routing algorithms mainly focus on the QoS of the service, rarely considering the security requirement of flow. To realize the secure transmission of flows in SAGIN, we propose an intelligent flow forwarding scheme with endogenous security based on Mimic Defense(ESMD-Flow). In this scheme, SDN controller will evaluate the reliability of nodes and links, isolate malicious nodes based on the reliability evaluation value, and adapt multipath routing strategy to ensure that flows are always forwarded along the most reliable multiple paths. In addition, in order to meet the security requirement of flows, we introduce the programming data plane to design a multiprotocol forwarding strategy for realizing the multiprotocol dynamic forwarding of flows. ESMD-Flow can reduce the network attack surface and improve the secure transmission capability of flows by implementing multipath routing and multi-protocol hybrid forwarding mechanism. The extensive simulations demonstrate that ESMD-Flow can significantly improve the average path reliability for routing and increase the difficulty of network eavesdropping while improving the network throughput and reducing the average packet delay.
基金Supported by the National High Technology Research and Development Program of China (No.2003AA103510).
文摘Recent advances in broadband technology have caused forwarding engines to handle pack- ets with over 10 gigabit per second. In this paper, we present a high-speed forwarding pipeline which can finish all of the routing and forwarding tasks in the way of pipelining. We also establish the analysis model of the pipeline with which one can evaluate some key performance parameters of the forwarding engine such as forwarding rate and forwarding delay. We find that the pipeline is of good scalability and can forward unicast packets up to the speed of 40Gbit/s.
基金supported by the National Natural Science Foundation of China under Grants No.61373139Postdoctoral Science Foundation of China under Grant No.2014M560379 and No.2015T80484Natural Science Foundation of Jiangsu Province under Grant No.BK2012833
文摘In this paper, the forwarding objective and mobility law of nodes in opportunistic networks are first investigated to establish a mathematical model for further analysis, then a gradually accelerated data forwarding algorithm is proposed. In this algorithm, according to the distance between data carriers （nodes） and the destination, some intermediate nodes are selected to relay the data. Especially, the forwarded copies can be increased when the delay reaches a threshold, to guarantee the required delivery ratio. The simulation results show that the proposed algorithm can effectively reduce the storage occupancies of nodes and forwarding delay, and guarantee the delivery ratio simultaneously.
基金Supported by National Natural Science Foundation of P. R. China (60673178) National Basic Research Program of P.R. China (2006 CB 303000)
文摘In wireless sensor networks, topology control plays an important role for data forwarding efficiency in the data gathering applications. In this paper, we present a novel topology control and data forwarding mechanism called REMUDA, which is designed for a practical indoor parking lot management system. REMUDA forms a tree-based hierarchical network topology which brings as many nodes as possible to be leaf nodes and constructs a virtual cluster structure. Meanwhile, it takes the reliability, stability and path length into account in the tree construction process. Through an experiment in a network of 30 real sensor nodes, we evaluate the performance of REMUDA and compare it with LEPS which is also a practical routing protocol in TinyOS. Experiment results show that REMUDA can achieve better performance than LEPS.
