With the arrival of the 5G era,wireless communication technologies and services are rapidly exhausting the limited spectrum resources.Spectrum auctions came into being,which can effectively utilize spectrum resources....With the arrival of the 5G era,wireless communication technologies and services are rapidly exhausting the limited spectrum resources.Spectrum auctions came into being,which can effectively utilize spectrum resources.Because of the complexity of the electronic spectrum auction network environment,the security of spectrum auction can not be guaranteed.Most scholars focus on researching the security of the single-sided auctions,while ignoring the practical scenario of a secure double spectrum auction where participants are composed of multiple sellers and buyers.Researchers begin to design the secure double spectrum auction mechanisms,in which two semi-honest agents are introduced to finish the spectrum auction rules.But these two agents may collude with each other or be bribed by buyers and sellers,which may create security risks,therefore,a secure double spectrum auction is proposed in this paper.Unlike traditional secure double spectrum auctions,the spectrum auction server with Software Guard Extensions(SGX)component is used in this paper,which is an Ethereum blockchain platform that performs spectrum auctions.A secure double spectrum protocol is also designed,using SGX technology and cryptographic tools such as Paillier cryptosystem,stealth address technology and one-time ring signatures to well protect the private information of spectrum auctions.In addition,the smart contracts provided by the Ethereum blockchain platform are executed to assist offline verification,and to verify important spectrum auction information to ensure the fairness and impartiality of spectrum auctions.Finally,security analysis and performance evaluation of our protocol are discussed.展开更多
Mobile offshore double-causeway pier system, a type of seashore unloading equipment, consists of two groups of multiple connected semi-submersible modules. This structure has wide application because most of the middl...Mobile offshore double-causeway pier system, a type of seashore unloading equipment, consists of two groups of multiple connected semi-submersible modules. This structure has wide application because most of the middle or mini type of vessels and ships can be moored to it. Based on the analysis of computational methods of multi-body motion response, a hydrodynamic model is set up and the three-dimensional potential theory in finite depth is adopted to calculate the three-dimensional motion response of this system. The double P-M spectrum is used to analyze the motion response in irregular waves. Different wave directions are specially taken into consideration, due to their various effects to the motion response. Furthermore, the calculated result is compared with that of the experiment, and it is proved that sway, heave, pitch and yaw motion are greatly constrained by mooring system. The comparison also indicates that the model can forecast the motion performance of the target, and that the calculated result can also be used as reference in connector and mooring system design.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government.(MSIT)(2021R1A2B5B02087169)the National Natural Science Foundation of China(Nos.62072092,62072093+4 种基金U1708262)the China Postdoctoral Science Foundation(No.2019M653568)the Key Research and Development Project of Hebei Province(No.20310702D)the Natural Science Foundation of Hebei Province(No.F2020501013)the Fundamental Research Funds for the Central Universities(No.N2023020)。
文摘With the arrival of the 5G era,wireless communication technologies and services are rapidly exhausting the limited spectrum resources.Spectrum auctions came into being,which can effectively utilize spectrum resources.Because of the complexity of the electronic spectrum auction network environment,the security of spectrum auction can not be guaranteed.Most scholars focus on researching the security of the single-sided auctions,while ignoring the practical scenario of a secure double spectrum auction where participants are composed of multiple sellers and buyers.Researchers begin to design the secure double spectrum auction mechanisms,in which two semi-honest agents are introduced to finish the spectrum auction rules.But these two agents may collude with each other or be bribed by buyers and sellers,which may create security risks,therefore,a secure double spectrum auction is proposed in this paper.Unlike traditional secure double spectrum auctions,the spectrum auction server with Software Guard Extensions(SGX)component is used in this paper,which is an Ethereum blockchain platform that performs spectrum auctions.A secure double spectrum protocol is also designed,using SGX technology and cryptographic tools such as Paillier cryptosystem,stealth address technology and one-time ring signatures to well protect the private information of spectrum auctions.In addition,the smart contracts provided by the Ethereum blockchain platform are executed to assist offline verification,and to verify important spectrum auction information to ensure the fairness and impartiality of spectrum auctions.Finally,security analysis and performance evaluation of our protocol are discussed.
基金This studyis supported bythe National Natural Science Foundation of China(Grant No.50570047)
文摘Mobile offshore double-causeway pier system, a type of seashore unloading equipment, consists of two groups of multiple connected semi-submersible modules. This structure has wide application because most of the middle or mini type of vessels and ships can be moored to it. Based on the analysis of computational methods of multi-body motion response, a hydrodynamic model is set up and the three-dimensional potential theory in finite depth is adopted to calculate the three-dimensional motion response of this system. The double P-M spectrum is used to analyze the motion response in irregular waves. Different wave directions are specially taken into consideration, due to their various effects to the motion response. Furthermore, the calculated result is compared with that of the experiment, and it is proved that sway, heave, pitch and yaw motion are greatly constrained by mooring system. The comparison also indicates that the model can forecast the motion performance of the target, and that the calculated result can also be used as reference in connector and mooring system design.
