In view of the problems of inconsistent data semantics,inconsistent data formats,and difficult data quality assurance between the railway engineering design phase and the construction and operation phase,as well as th...In view of the problems of inconsistent data semantics,inconsistent data formats,and difficult data quality assurance between the railway engineering design phase and the construction and operation phase,as well as the difficulty in fully realizing the value of design results,this paper proposes a design and implementation scheme for a railway engineering collaborative design platform.The railway engineering collaborative design platform mainly includes functional modules such as metadata management,design collaboration,design delivery management,model component library,model rendering services,and Building Information Modeling(BIM)application services.Based on this,research is conducted on multi-disciplinary parameterized collaborative design technology for railway engineering,infrastructure data management and delivery technology,and design multi-source data fusion and application technology.The railway engineering collaborative design platform is compared with other railway design software to further validate its advantages and advanced features.The platform has been widely applied in multiple railway construction projects,greatly improving the design and project management efficiency.展开更多
In this paper, we present the virtual desktop that uses a novel methodology and related metrics to benchmark thin client based on Data Delivery Networks (DDN) in terms of scalability and reliability. Most studies of t...In this paper, we present the virtual desktop that uses a novel methodology and related metrics to benchmark thin client based on Data Delivery Networks (DDN) in terms of scalability and reliability. Most studies of the wireless networks mainly focus on system performance and power consumption circuit system;the main target has been separated in terms of Data operation and GUI operation by DDN. The communication protocol for wireless communication may play a major role in energy consumption and other important factors. The portable devices like Personal Digital Assistance (PDA) and others are mainly focusing on the efficient energy consumption (power control) in wireless networks. Here we focus on energy efficiency, algorithmic efficiency, virtualization and resource allocation;these are the main aims of the authors. The foremost research in the direction of wireless computing in saving energy and reducing carbon foot prints is also the challenging part. This is the study proof of brief account of wireless networks.展开更多
In view of the fact that current data delivery methods are not enough to meet the security requirements of today’s distributed crowd sensing,and the data delivery methods are not flexible enough,this paper proposes a...In view of the fact that current data delivery methods are not enough to meet the security requirements of today’s distributed crowd sensing,and the data delivery methods are not flexible enough,this paper proposes a crowd sensing data interaction method based on tangle directed acyclic graph(DAG)network.In this method,users and platforms are regarded as nodes of the network in the process of performing crowd sensing tasks.First,the heaviest chain is generated through the main chain strategy to ensure the stability of the network.Then,the hidden Markov model(HMM)prediction model is used to improve the correlation of the perceived data to improve the performance.Then,the confidential transaction and commitment algorithm is used to ensure the reliability of the transaction,overcome the security risks faced by the trusted third party,and simplify the group intelligence aware transaction mode.Finally,through simulation experiments,the security and feasibility of the group intelligence aware data delivery method based on tangle DAG network are verified.展开更多
Deep space communication has its own features such as long propagation delays,heavy noise,asymmetric link rates,and intermittent connectivity in space,therefore TCP/IP protocol cannot perform as well as it does in ter...Deep space communication has its own features such as long propagation delays,heavy noise,asymmetric link rates,and intermittent connectivity in space,therefore TCP/IP protocol cannot perform as well as it does in terrestrial communications.Accordingly,the Consultative Committee for Space Data Systems(CCSDS) developed CCSDS File Delivery Protocol(CFDP),which sets standards of efficient file delivery service capable of transferring files to and from mass memory located in the space segment.In CFDP,four optional acknowledge modes are supported to make the communication more reliable.In this paper,we gave a general introduction of typical communication process in CFDP and analysis of its four Negative Acknowledgement(NAK) modes on the respect of file delivery delay and times of retransmission.We found out that despite the shortest file delivery delay,immediate NAK mode suffers from the problem that frequent retransmission may probably lead to network congestion.Thus,we proposed a new mode,the error counter-based NAK mode.By simulation of the case focused on the link between a deep space probe on Mars and a ter-restrial station on Earth,we concluded that error counter-based NAK mode has successfully reduced the retransmission times at negligible cost of certain amount of file delivery delay.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB2600405).
文摘In view of the problems of inconsistent data semantics,inconsistent data formats,and difficult data quality assurance between the railway engineering design phase and the construction and operation phase,as well as the difficulty in fully realizing the value of design results,this paper proposes a design and implementation scheme for a railway engineering collaborative design platform.The railway engineering collaborative design platform mainly includes functional modules such as metadata management,design collaboration,design delivery management,model component library,model rendering services,and Building Information Modeling(BIM)application services.Based on this,research is conducted on multi-disciplinary parameterized collaborative design technology for railway engineering,infrastructure data management and delivery technology,and design multi-source data fusion and application technology.The railway engineering collaborative design platform is compared with other railway design software to further validate its advantages and advanced features.The platform has been widely applied in multiple railway construction projects,greatly improving the design and project management efficiency.
文摘In this paper, we present the virtual desktop that uses a novel methodology and related metrics to benchmark thin client based on Data Delivery Networks (DDN) in terms of scalability and reliability. Most studies of the wireless networks mainly focus on system performance and power consumption circuit system;the main target has been separated in terms of Data operation and GUI operation by DDN. The communication protocol for wireless communication may play a major role in energy consumption and other important factors. The portable devices like Personal Digital Assistance (PDA) and others are mainly focusing on the efficient energy consumption (power control) in wireless networks. Here we focus on energy efficiency, algorithmic efficiency, virtualization and resource allocation;these are the main aims of the authors. The foremost research in the direction of wireless computing in saving energy and reducing carbon foot prints is also the challenging part. This is the study proof of brief account of wireless networks.
文摘In view of the fact that current data delivery methods are not enough to meet the security requirements of today’s distributed crowd sensing,and the data delivery methods are not flexible enough,this paper proposes a crowd sensing data interaction method based on tangle directed acyclic graph(DAG)network.In this method,users and platforms are regarded as nodes of the network in the process of performing crowd sensing tasks.First,the heaviest chain is generated through the main chain strategy to ensure the stability of the network.Then,the hidden Markov model(HMM)prediction model is used to improve the correlation of the perceived data to improve the performance.Then,the confidential transaction and commitment algorithm is used to ensure the reliability of the transaction,overcome the security risks faced by the trusted third party,and simplify the group intelligence aware transaction mode.Finally,through simulation experiments,the security and feasibility of the group intelligence aware data delivery method based on tangle DAG network are verified.
文摘Deep space communication has its own features such as long propagation delays,heavy noise,asymmetric link rates,and intermittent connectivity in space,therefore TCP/IP protocol cannot perform as well as it does in terrestrial communications.Accordingly,the Consultative Committee for Space Data Systems(CCSDS) developed CCSDS File Delivery Protocol(CFDP),which sets standards of efficient file delivery service capable of transferring files to and from mass memory located in the space segment.In CFDP,four optional acknowledge modes are supported to make the communication more reliable.In this paper,we gave a general introduction of typical communication process in CFDP and analysis of its four Negative Acknowledgement(NAK) modes on the respect of file delivery delay and times of retransmission.We found out that despite the shortest file delivery delay,immediate NAK mode suffers from the problem that frequent retransmission may probably lead to network congestion.Thus,we proposed a new mode,the error counter-based NAK mode.By simulation of the case focused on the link between a deep space probe on Mars and a ter-restrial station on Earth,we concluded that error counter-based NAK mode has successfully reduced the retransmission times at negligible cost of certain amount of file delivery delay.
