Soft robotic crawlers have limited payload capacity and crawling speed.This study proposes a high-performance inchworm-like modular robotic crawler based on fluidic prestressed composite(FPC)actuators.The FPC actuator...Soft robotic crawlers have limited payload capacity and crawling speed.This study proposes a high-performance inchworm-like modular robotic crawler based on fluidic prestressed composite(FPC)actuators.The FPC actuator is precurved and a pneumatic source is used to flatten it,requiring no energy cost to maintain the equilibrium curved shape.Pressurizing and depressurizing the actuators generate alternating stretching and bending motions of the actuators,achieving the crawling motion of the robotic crawler.Multi-modal locomotion(crawling,turning,and pipe climbing)is achieved by modular reconfiguration and gait design.An analytical kinematic model is proposed to characterize the quasi-static curvature and step size of a single-module crawler.Multiple configurations of robotic crawlers are fabricated to demonstrate the crawling ability of the proposed design.A set of systematic experiments are set up and conducted to understand how crawler responses vary as a function of FPC prestrains,input pressures,and actuation frequencies.As per the experiments,the maximum carrying load ratio(carrying load divided by robot weight)is found to be 22.32,and the highest crawling velocity is 3.02 body length(BL)per second(392 mm/s).Multi-modal capabilities are demonstrated by reconfiguring three soft crawlers,including a matrix crawler robot crawling in amphibious environments,and an inching crawler turning at an angular velocity of 2/s,as well as earthworm-like crawling robots climbing a 20 inclination slope and pipe.展开更多
Artificial soft actuators,featured with non-equilibrium internal circumstance and fast,programmable shape transformations,have attracted strong research interest recently due to their flexibility,highly controllable,a...Artificial soft actuators,featured with non-equilibrium internal circumstance and fast,programmable shape transformations,have attracted strong research interest recently due to their flexibility,highly controllable,and designability.However,wireless soft actuators,achieving the locomotion on different large slopes with multiple energy conversion,have been rarely reported.Herein,we create a asymmetric bilayer strategy to construct autonomous soft crawler via“breathing”moisture to motivate the mechanical deformation.The soft crawlers present conspicuous performances including periodic tumbler locomotion predicted via improved Timoshenko’s equation,multiple reversible shape-morphing(circle,helix,despiralization,etc.)determined by their fiber orientation,controlled drive mode(front drive and rear drive)and rapid climb speed(4.76 cm/min)at wide slope angles.Through architecture design,they can be series-wound or shunt-wound to construct multijoint complex actuators.Besides climbing,a intelligent soft ring-pull with admirable cycle performance for preventing overheating or something untouchable,has been proposed.The soft crawlers also realize multiple energy conversion to be actuated by light irradiation.We envision that this soft crawler system has an enormous potential in intelligent machine,microscopic diagnosis and treatment,biosensing,energy harvesting and conversion.展开更多
Web crawlers have been misused for several malicious purposes such as downloading server data without permission from the website administrator.Moreover,armoured crawlers are evolving against new anti-crawler mechanis...Web crawlers have been misused for several malicious purposes such as downloading server data without permission from the website administrator.Moreover,armoured crawlers are evolving against new anti-crawler mechanisms in the arm races between crawler developers and crawler defenders.In this paper,based on one observation that normal users and malicious crawlers have different short-term and long-term download behaviours,we develop a new anti-crawler mechanism called PathMarker to detect and constrain persistent distributed crawlers.By adding a marker to each Uniform Resource Locator(URL),we can trace the page that leads to the access of this URL and the user identity who accesses this URL.With this supporting information,we can not only perform more accurate heuristic detection using the path related features,but also develop a Support Vector Machine based machine learning detection model to distinguish malicious crawlers from normal users via inspecting their different patterns of URL visiting paths and URL visiting timings.In addition to effectively detecting crawlers at the earliest stage,PathMarker can dramatically suppress the scraping efficiency of crawlers before they are detected.We deploy our approach on an online forum website,and the evaluation results show that PathMarker can quickly capture all 6 open-source and in-house crawlers,plus two external crawlers(i.e.,Googlebots and Yahoo Slurp).展开更多
Web crawlers have been misused for several malicious purposes such as downloading server data without permission from the website administrator.Moreover,armoured crawlers are evolving against new anti-crawler mechanis...Web crawlers have been misused for several malicious purposes such as downloading server data without permission from the website administrator.Moreover,armoured crawlers are evolving against new anti-crawler mechanisms in the arm races between crawler developers and crawler defenders.In this paper,based on one observation that normal users and malicious crawlers have different short-term and long-term download behaviours,we develop a new anti-crawler mechanism called PathMarker to detect and constrain persistent distributed crawlers.By adding a marker to each Uniform Resource Locator(URL),we can trace the page that leads to the access of this URL and the user identity who accesses this URL.With this supporting information,we can not only perform more accurate heuristic detection using the path related features,but also develop a Support Vector Machine based machine learning detection model to distinguish malicious crawlers from normal users via inspecting their different patterns of URL visiting paths and URL visiting timings.In addition to effectively detecting crawlers at the earliest stage,PathMarker can dramatically suppress the scraping efficiency of crawlers before they are detected.We deploy our approach on an online forum website,and the evaluation results show that PathMarker can quickly capture all 6 open-source and in-house crawlers,plus two external crawlers(i.e.,Googlebots and Yahoo Slurp).展开更多
The cyber-criminal compromises end-hosts(bots)to configure a network of bots(botnet).The cyber-criminals are also looking for an evolved architecture that makes their techniques more resilient and stealthier such as P...The cyber-criminal compromises end-hosts(bots)to configure a network of bots(botnet).The cyber-criminals are also looking for an evolved architecture that makes their techniques more resilient and stealthier such as Peer-to-Peer(P2P)networks.The P2P botnets leverage the privileges of the decentralized nature of P2P networks.Consequently,the P2P botnets exploit the resilience of this architecture to be arduous against take-down procedures.Some P2P botnets are smarter to be stealthy in their Commandand-Control mechanisms(C2)and elude the standard discovery mechanisms.Therefore,the other side of this cyberwar is the monitor.The P2P botnet monitoring is an exacting mission because the monitoring must care about many aspects simultaneously.Some aspects pertain to the existing monitoring approaches,some pertain to the nature of P2P networks,and some to counter the botnets,i.e.,the anti-monitoring mechanisms.All these challenges should be considered in P2P botnet monitoring.To begin with,this paper provides an anatomy of P2P botnets.Thereafter,this paper exhaustively reviews the existing monitoring approaches of P2P botnets and thoroughly discusses each to reveal its advantages and disadvantages.In addition,this paper groups the monitoring approaches into three groups:passive,active,and hybrid monitoring approaches.Furthermore,this paper also discusses the functional and non-functional requirements of advanced monitoring.In conclusion,this paper ends by epitomizing the challenges of various aspects and gives future avenues for better monitoring of P2P botnets.展开更多
As data grows in size,search engines face new challenges in extracting more relevant content for users’searches.As a result,a number of retrieval and ranking algorithms have been employed to ensure that the results a...As data grows in size,search engines face new challenges in extracting more relevant content for users’searches.As a result,a number of retrieval and ranking algorithms have been employed to ensure that the results are relevant to the user’s requirements.Unfortunately,most existing indexes and ranking algo-rithms crawl documents and web pages based on a limited set of criteria designed to meet user expectations,making it impossible to deliver exceptionally accurate results.As a result,this study investigates and analyses how search engines work,as well as the elements that contribute to higher ranks.This paper addresses the issue of bias by proposing a new ranking algorithm based on the PageRank(PR)algorithm,which is one of the most widely used page ranking algorithms We pro-pose weighted PageRank(WPR)algorithms to test the relationship between these various measures.The Weighted Page Rank(WPR)model was used in three dis-tinct trials to compare the rankings of documents and pages based on one or more user preferences criteria.Thefindings of utilizing the Weighted Page Rank model showed that using multiple criteria to rankfinal pages is better than using only one,and that some criteria had a greater impact on ranking results than others.展开更多
The mechanical properties of deep-sea sediments during the driving process of crawler collectors are essential factors in the design of mining systems.In this study,a crawler load is divided into a normal compression ...The mechanical properties of deep-sea sediments during the driving process of crawler collectors are essential factors in the design of mining systems.In this study,a crawler load is divided into a normal compression load and a horizontal shear load.Then,the internal stress state of sedimentary soil is examined through a theoretical calculation and finite element numerical simulation.Finally,the driving of crawlers is simulated by changing the relative spatial position between the load and stress unit,obtaining the stress path of the soil unit.Based on the calculation results,the effect of the horizontal shear load on the soil stress response is analyzed at different depths,and the spatial variation law of the soil stress path is examined.The results demonstrate that the horizontal shear load has a significant effect on the rotation of the principal stress,and the reverse rotation of the principal stress axis becomes obvious with the increase in the burial depth.The stress path curve of the soil is different at various depths.The spatial variation rule of the stress path of the shallow soil is complex,whereas the stress path curve of the deep soil tends to shrink as the depth increases.The stress path of the corresponding depth should be selected according to the actual research purpose and applied to the laboratory test.展开更多
With the frequent occurrence of telecommunications and networkfraud crimes in recent years, new frauds have emerged one after another whichhas caused huge losses to the people. However, due to the lack of an effective...With the frequent occurrence of telecommunications and networkfraud crimes in recent years, new frauds have emerged one after another whichhas caused huge losses to the people. However, due to the lack of an effectivepreventive mechanism, the police are often in a passive position. Usingtechnologies such as web crawlers, feature engineering, deep learning, andartificial intelligence, this paper proposes a user portrait fraudwarning schemebased on Weibo public data. First, we perform preliminary screening andcleaning based on the keyword “defrauded” to obtain valid fraudulent userIdentity Documents (IDs). The basic information and account information ofthese users is user-labeled to achieve the purpose of distinguishing the typesof fraud. Secondly, through feature engineering technologies such as avatarrecognition, Artificial Intelligence (AI) sentiment analysis, data screening,and follower blogger type analysis, these pictures and texts will be abstractedinto user preferences and personality characteristics which integrate multidimensionalinformation to build user portraits. Third, deep neural networktraining is performed on the cube. 80% percent of the data is predicted basedon the N-way K-shot problem and used to train the model, and the remaining20% is used for model accuracy evaluation. Experiments have shown thatFew-short learning has higher accuracy compared with Long Short TermMemory (LSTM), Recurrent Neural Networks (RNN) and ConvolutionalNeural Network (CNN). On this basis, this paper develops a WeChat smallprogram for early warning of telecommunications network fraud based onuser portraits. When the user enters some personal information on the frontend, the back-end database can perform correlation analysis by itself, so as tomatch the most likely fraud types and give relevant early warning information.The fraud warning model is highly scaleable. The data of other Applications(APPs) can be extended to further improve the efficiency of anti-fraud whichhas extremely high public welfare value.展开更多
In order to improve the elbow passing performance and different diameter adaptability of pipeline robot,a supported crawler pipeline robot is designed,which adopts screw nut mechanism and hinge four-bar mechanism to a...In order to improve the elbow passing performance and different diameter adaptability of pipeline robot,a supported crawler pipeline robot is designed,which adopts screw nut mechanism and hinge four-bar mechanism to adapt to the complex environment such as variable diameter pipeline and elbow.The steering characteristics passing through the elbow are studied,the kinematic of pipeline robot bending steering is established,the geometric constraint(GC)and steering constraint(SC)in the elbow are analyzed,and the steering experiment is conducted.The results show that the robot can pass through the elbow by the SC model.The SC model can reduce the motor current and energy consumption when the robot passes through the elbow.展开更多
Focused crawlers are important tools to support applications such as specialized Web portals, online searching, and Web search engines. A topic driven crawler chooses the best URLs and relevant pages to pursue during ...Focused crawlers are important tools to support applications such as specialized Web portals, online searching, and Web search engines. A topic driven crawler chooses the best URLs and relevant pages to pursue during Web crawling. It is difficult to deal with irrelevant pages. This paper presents a novel focused crawler framework. In our focused crawler, we propose a method to overcome some of the limitations of dealing with the irrelevant pages. We also introduce the implementation of our focused crawler and present some important metrics and an evaluation function for ranking pages relevance. The experimental result shows that our crawler can obtain more "important" pages and has a high precision and recall value.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.62203174the Guangzhou Municipal Science and Technology Project under Grant No.202201010179.
文摘Soft robotic crawlers have limited payload capacity and crawling speed.This study proposes a high-performance inchworm-like modular robotic crawler based on fluidic prestressed composite(FPC)actuators.The FPC actuator is precurved and a pneumatic source is used to flatten it,requiring no energy cost to maintain the equilibrium curved shape.Pressurizing and depressurizing the actuators generate alternating stretching and bending motions of the actuators,achieving the crawling motion of the robotic crawler.Multi-modal locomotion(crawling,turning,and pipe climbing)is achieved by modular reconfiguration and gait design.An analytical kinematic model is proposed to characterize the quasi-static curvature and step size of a single-module crawler.Multiple configurations of robotic crawlers are fabricated to demonstrate the crawling ability of the proposed design.A set of systematic experiments are set up and conducted to understand how crawler responses vary as a function of FPC prestrains,input pressures,and actuation frequencies.As per the experiments,the maximum carrying load ratio(carrying load divided by robot weight)is found to be 22.32,and the highest crawling velocity is 3.02 body length(BL)per second(392 mm/s).Multi-modal capabilities are demonstrated by reconfiguring three soft crawlers,including a matrix crawler robot crawling in amphibious environments,and an inching crawler turning at an angular velocity of 2/s,as well as earthworm-like crawling robots climbing a 20 inclination slope and pipe.
基金financially supported by the National Natural Science Foundation of China(Nos.22001175,51973118,22175121 and 52003160)Key-Area Research and Development Program of Guangdong Province(Nos.2019B010929002 and 2019B010941001)+3 种基金the Natural Science Foundation of Guangdong Province(No.2020A1515010644)the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08C642)Shenzhen Science and Technology Program(Nos.JCYJ20210324095412035,JCYJ20190808113005643,JCYJ20170818093832350 and JCYJ20180507184711069)the start-up fund of Shenzhen University(No.000002110820)。
文摘Artificial soft actuators,featured with non-equilibrium internal circumstance and fast,programmable shape transformations,have attracted strong research interest recently due to their flexibility,highly controllable,and designability.However,wireless soft actuators,achieving the locomotion on different large slopes with multiple energy conversion,have been rarely reported.Herein,we create a asymmetric bilayer strategy to construct autonomous soft crawler via“breathing”moisture to motivate the mechanical deformation.The soft crawlers present conspicuous performances including periodic tumbler locomotion predicted via improved Timoshenko’s equation,multiple reversible shape-morphing(circle,helix,despiralization,etc.)determined by their fiber orientation,controlled drive mode(front drive and rear drive)and rapid climb speed(4.76 cm/min)at wide slope angles.Through architecture design,they can be series-wound or shunt-wound to construct multijoint complex actuators.Besides climbing,a intelligent soft ring-pull with admirable cycle performance for preventing overheating or something untouchable,has been proposed.The soft crawlers also realize multiple energy conversion to be actuated by light irradiation.We envision that this soft crawler system has an enormous potential in intelligent machine,microscopic diagnosis and treatment,biosensing,energy harvesting and conversion.
基金This work is supported by U.S.Office of Naval Research under grants N00014-16-1-3214 and N00014-16-1-3216.
文摘Web crawlers have been misused for several malicious purposes such as downloading server data without permission from the website administrator.Moreover,armoured crawlers are evolving against new anti-crawler mechanisms in the arm races between crawler developers and crawler defenders.In this paper,based on one observation that normal users and malicious crawlers have different short-term and long-term download behaviours,we develop a new anti-crawler mechanism called PathMarker to detect and constrain persistent distributed crawlers.By adding a marker to each Uniform Resource Locator(URL),we can trace the page that leads to the access of this URL and the user identity who accesses this URL.With this supporting information,we can not only perform more accurate heuristic detection using the path related features,but also develop a Support Vector Machine based machine learning detection model to distinguish malicious crawlers from normal users via inspecting their different patterns of URL visiting paths and URL visiting timings.In addition to effectively detecting crawlers at the earliest stage,PathMarker can dramatically suppress the scraping efficiency of crawlers before they are detected.We deploy our approach on an online forum website,and the evaluation results show that PathMarker can quickly capture all 6 open-source and in-house crawlers,plus two external crawlers(i.e.,Googlebots and Yahoo Slurp).
基金supported by U.S.Office of Naval Research under grants N00014-16-1-3214 and N00014-16-1-3216.
文摘Web crawlers have been misused for several malicious purposes such as downloading server data without permission from the website administrator.Moreover,armoured crawlers are evolving against new anti-crawler mechanisms in the arm races between crawler developers and crawler defenders.In this paper,based on one observation that normal users and malicious crawlers have different short-term and long-term download behaviours,we develop a new anti-crawler mechanism called PathMarker to detect and constrain persistent distributed crawlers.By adding a marker to each Uniform Resource Locator(URL),we can trace the page that leads to the access of this URL and the user identity who accesses this URL.With this supporting information,we can not only perform more accurate heuristic detection using the path related features,but also develop a Support Vector Machine based machine learning detection model to distinguish malicious crawlers from normal users via inspecting their different patterns of URL visiting paths and URL visiting timings.In addition to effectively detecting crawlers at the earliest stage,PathMarker can dramatically suppress the scraping efficiency of crawlers before they are detected.We deploy our approach on an online forum website,and the evaluation results show that PathMarker can quickly capture all 6 open-source and in-house crawlers,plus two external crawlers(i.e.,Googlebots and Yahoo Slurp).
基金This work was supported by the Ministry of Higher Education Malaysia’s Fundamental Research Grant Scheme under Grant FRGS/1/2021/ICT07/USM/03/1.
文摘The cyber-criminal compromises end-hosts(bots)to configure a network of bots(botnet).The cyber-criminals are also looking for an evolved architecture that makes their techniques more resilient and stealthier such as Peer-to-Peer(P2P)networks.The P2P botnets leverage the privileges of the decentralized nature of P2P networks.Consequently,the P2P botnets exploit the resilience of this architecture to be arduous against take-down procedures.Some P2P botnets are smarter to be stealthy in their Commandand-Control mechanisms(C2)and elude the standard discovery mechanisms.Therefore,the other side of this cyberwar is the monitor.The P2P botnet monitoring is an exacting mission because the monitoring must care about many aspects simultaneously.Some aspects pertain to the existing monitoring approaches,some pertain to the nature of P2P networks,and some to counter the botnets,i.e.,the anti-monitoring mechanisms.All these challenges should be considered in P2P botnet monitoring.To begin with,this paper provides an anatomy of P2P botnets.Thereafter,this paper exhaustively reviews the existing monitoring approaches of P2P botnets and thoroughly discusses each to reveal its advantages and disadvantages.In addition,this paper groups the monitoring approaches into three groups:passive,active,and hybrid monitoring approaches.Furthermore,this paper also discusses the functional and non-functional requirements of advanced monitoring.In conclusion,this paper ends by epitomizing the challenges of various aspects and gives future avenues for better monitoring of P2P botnets.
文摘As data grows in size,search engines face new challenges in extracting more relevant content for users’searches.As a result,a number of retrieval and ranking algorithms have been employed to ensure that the results are relevant to the user’s requirements.Unfortunately,most existing indexes and ranking algo-rithms crawl documents and web pages based on a limited set of criteria designed to meet user expectations,making it impossible to deliver exceptionally accurate results.As a result,this study investigates and analyses how search engines work,as well as the elements that contribute to higher ranks.This paper addresses the issue of bias by proposing a new ranking algorithm based on the PageRank(PR)algorithm,which is one of the most widely used page ranking algorithms We pro-pose weighted PageRank(WPR)algorithms to test the relationship between these various measures.The Weighted Page Rank(WPR)model was used in three dis-tinct trials to compare the rankings of documents and pages based on one or more user preferences criteria.Thefindings of utilizing the Weighted Page Rank model showed that using multiple criteria to rankfinal pages is better than using only one,and that some criteria had a greater impact on ranking results than others.
基金supported by the National Natural Science Foundation of China(Nos.U1906234,51822904,51579082)the Fundamental Research Funds for the Central Universities(No.2020MS027).
文摘The mechanical properties of deep-sea sediments during the driving process of crawler collectors are essential factors in the design of mining systems.In this study,a crawler load is divided into a normal compression load and a horizontal shear load.Then,the internal stress state of sedimentary soil is examined through a theoretical calculation and finite element numerical simulation.Finally,the driving of crawlers is simulated by changing the relative spatial position between the load and stress unit,obtaining the stress path of the soil unit.Based on the calculation results,the effect of the horizontal shear load on the soil stress response is analyzed at different depths,and the spatial variation law of the soil stress path is examined.The results demonstrate that the horizontal shear load has a significant effect on the rotation of the principal stress,and the reverse rotation of the principal stress axis becomes obvious with the increase in the burial depth.The stress path curve of the soil is different at various depths.The spatial variation rule of the stress path of the shallow soil is complex,whereas the stress path curve of the deep soil tends to shrink as the depth increases.The stress path of the corresponding depth should be selected according to the actual research purpose and applied to the laboratory test.
文摘With the frequent occurrence of telecommunications and networkfraud crimes in recent years, new frauds have emerged one after another whichhas caused huge losses to the people. However, due to the lack of an effectivepreventive mechanism, the police are often in a passive position. Usingtechnologies such as web crawlers, feature engineering, deep learning, andartificial intelligence, this paper proposes a user portrait fraudwarning schemebased on Weibo public data. First, we perform preliminary screening andcleaning based on the keyword “defrauded” to obtain valid fraudulent userIdentity Documents (IDs). The basic information and account information ofthese users is user-labeled to achieve the purpose of distinguishing the typesof fraud. Secondly, through feature engineering technologies such as avatarrecognition, Artificial Intelligence (AI) sentiment analysis, data screening,and follower blogger type analysis, these pictures and texts will be abstractedinto user preferences and personality characteristics which integrate multidimensionalinformation to build user portraits. Third, deep neural networktraining is performed on the cube. 80% percent of the data is predicted basedon the N-way K-shot problem and used to train the model, and the remaining20% is used for model accuracy evaluation. Experiments have shown thatFew-short learning has higher accuracy compared with Long Short TermMemory (LSTM), Recurrent Neural Networks (RNN) and ConvolutionalNeural Network (CNN). On this basis, this paper develops a WeChat smallprogram for early warning of telecommunications network fraud based onuser portraits. When the user enters some personal information on the frontend, the back-end database can perform correlation analysis by itself, so as tomatch the most likely fraud types and give relevant early warning information.The fraud warning model is highly scaleable. The data of other Applications(APPs) can be extended to further improve the efficiency of anti-fraud whichhas extremely high public welfare value.
基金Supported by the National Natural Science Foundation of China(No.51775323).
文摘In order to improve the elbow passing performance and different diameter adaptability of pipeline robot,a supported crawler pipeline robot is designed,which adopts screw nut mechanism and hinge four-bar mechanism to adapt to the complex environment such as variable diameter pipeline and elbow.The steering characteristics passing through the elbow are studied,the kinematic of pipeline robot bending steering is established,the geometric constraint(GC)and steering constraint(SC)in the elbow are analyzed,and the steering experiment is conducted.The results show that the robot can pass through the elbow by the SC model.The SC model can reduce the motor current and energy consumption when the robot passes through the elbow.
基金Supported by the National Natural Science Foun-dation of China (60373099)
文摘Focused crawlers are important tools to support applications such as specialized Web portals, online searching, and Web search engines. A topic driven crawler chooses the best URLs and relevant pages to pursue during Web crawling. It is difficult to deal with irrelevant pages. This paper presents a novel focused crawler framework. In our focused crawler, we propose a method to overcome some of the limitations of dealing with the irrelevant pages. We also introduce the implementation of our focused crawler and present some important metrics and an evaluation function for ranking pages relevance. The experimental result shows that our crawler can obtain more "important" pages and has a high precision and recall value.