Low tide terrace beach is a main beach type along South China coasts with strong tidal actions.How strong tides affect wave transformations on low tide terrace beach still remains unclear.In this study,in-situ measure...Low tide terrace beach is a main beach type along South China coasts with strong tidal actions.How strong tides affect wave transformations on low tide terrace beach still remains unclear.In this study,in-situ measurements are conducted on the low terrace beach at Xisha Bay to provide quantitative descriptions of wave shoaling and shore-breaker phenomena under the tidal effects.It is found that wave breaking is unsaturated on the low tide terrace beach at Xisha Bay.Magnitudes of wave skewness and asymmetry increase as wave shoals and achieve the maximum value at the shore-breaker,and then decrease rapidly.Mean energy dissipation rates of shore-breakers are tide-modulated since the bottom slope changes at the shoreward boundary of wave propagation in a tidal cycle.The remaining wave energy flux at the initialization of the shore-breaker is 1%–12%of offshore wave energy flux,and the energy flux ratio decreases with increasing offshore wave heights.Wave attenuation at shore-breakers can be estimated directly from offshore wave conditions based on findings in this study,favoring designs of seawalls or beach nourishment projects.Field datasets on wave transformations can also be used for verifications of wave numerical models.展开更多
Blockchain has recently emerged as a research trend,with potential applications in a broad range of industries and context.One particular successful Blockchain technology is smart contract,which is widely used in comm...Blockchain has recently emerged as a research trend,with potential applications in a broad range of industries and context.One particular successful Blockchain technology is smart contract,which is widely used in commercial settings(e.g.,high value financial transactions).This,however,has security implications due to the potential to financially benefit from a security incident(e.g.,identification and exploitation of a vulnerability in the smart contract or its implementation).Among,Ethereum is the most active and arresting.Hence,in this paper,we systematically review existing research efforts on Ethereum smart contract security,published between 2015 and 2019.Specifically,we focus on how smart contracts can be maliciously exploited and targeted,such as security issues of contract program model,vulnerabilities in the program and safety consideration introduced by program execution environment.We also identify potential research opportunities and future research agenda.展开更多
基金The Key Program of National Natural Science Foundation of China under contract No.41930538the Open Research Fund of State Key Laboratory of Estuarine and Coastal Research,East China Normal University under contract No.SKLEC-KF202203+3 种基金the National Natural Science Foundation of China under contract No.52201317the National Key Research and Development Program under contract No.2022YFC3106102the China Postdoctoral Science Foundation under contract No.2022M711023the Jiangsu Funding Program for Excellent Postdoctoral Talent under contract No.2022ZB148.
文摘Low tide terrace beach is a main beach type along South China coasts with strong tidal actions.How strong tides affect wave transformations on low tide terrace beach still remains unclear.In this study,in-situ measurements are conducted on the low terrace beach at Xisha Bay to provide quantitative descriptions of wave shoaling and shore-breaker phenomena under the tidal effects.It is found that wave breaking is unsaturated on the low tide terrace beach at Xisha Bay.Magnitudes of wave skewness and asymmetry increase as wave shoals and achieve the maximum value at the shore-breaker,and then decrease rapidly.Mean energy dissipation rates of shore-breakers are tide-modulated since the bottom slope changes at the shoreward boundary of wave propagation in a tidal cycle.The remaining wave energy flux at the initialization of the shore-breaker is 1%–12%of offshore wave energy flux,and the energy flux ratio decreases with increasing offshore wave heights.Wave attenuation at shore-breakers can be estimated directly from offshore wave conditions based on findings in this study,favoring designs of seawalls or beach nourishment projects.Field datasets on wave transformations can also be used for verifications of wave numerical models.
基金This work was supported by the National Key Research and Development(R&D)Plan of China(2019YFB2101700)the Science and Technology Program of Guangzhou(201902020016)+2 种基金the Shenzhen Fundamental Research Program(JCYJ20170413114215614)the Guangdong Provincial Science and Technology Plan Project(2017B010124001)the Guangdong Provincial Key R&D Plan Project(2019B010139001).
文摘Blockchain has recently emerged as a research trend,with potential applications in a broad range of industries and context.One particular successful Blockchain technology is smart contract,which is widely used in commercial settings(e.g.,high value financial transactions).This,however,has security implications due to the potential to financially benefit from a security incident(e.g.,identification and exploitation of a vulnerability in the smart contract or its implementation).Among,Ethereum is the most active and arresting.Hence,in this paper,we systematically review existing research efforts on Ethereum smart contract security,published between 2015 and 2019.Specifically,we focus on how smart contracts can be maliciously exploited and targeted,such as security issues of contract program model,vulnerabilities in the program and safety consideration introduced by program execution environment.We also identify potential research opportunities and future research agenda.
