The crashworthiness of the cargo containment systems （CCSs） of a floating liquid natural gas （FLNG） and the side structures in side-by-side offioading operations scenario are studied in this paper. An FLNG vessel ...The crashworthiness of the cargo containment systems （CCSs） of a floating liquid natural gas （FLNG） and the side structures in side-by-side offioading operations scenario are studied in this paper. An FLNG vessel is exposed to potential threats from collisions with a liquid natural gas carrier （LNGC） during the offioading operations, which has been confirmed by a model test of FLNG-LNGC side-by-side offioading operations. A nonlinear finite element code LS-DYNA is used to simulate the collision scenarios during the offioading operations. Finite element models of an FLNG vessel and an LNGC are established for the purpose of this study, including a detailed LNG cargo containment system in the FLNG side model. Based on the parameters obtained from the model test and potential dangerous accidents, typical collision scenarios are defined to conduct a comprehensive study. To evaluate the safety of the FLNG vessel, a limit state is proposed based on the structural responses of the LNG CCS. The different characteristics of the structural responses for the primary structural components, energy dissipation and collision forces are obtained for various scenarios. Deformation of the inner hull is found to have a great effect on the responses of the LNG CCS, with approximately 160 mm deformation corresponding to the limit state. Densely arranged web frames can absorb over 35% of the collision energy and be proved to greatly enhance the crashwo- rthiness of the FLNG side structures.展开更多
Fog computing is an emerging paradigm of cloud computing which to meet the growing computation demand of mobile application. It can help mobile devices to overcome resource constraints by offloading the computationall...Fog computing is an emerging paradigm of cloud computing which to meet the growing computation demand of mobile application. It can help mobile devices to overcome resource constraints by offloading the computationally intensive tasks to cloud servers. The challenge of the cloud is to minimize the time of data transfer and task execution to the user, whose location changes owing to mobility, and the energy consumption for the mobile device. To provide satisfactory computation performance is particularly challenging in the fog computing environment. In this paper, we propose a novel fog computing model and offloading policy which can effectively bring the fog computing power closer to the mobile user. The fog computing model consist of remote cloud nodes and local cloud nodes, which is attached to wireless access infrastructure. And we give task offloading policy taking into account executi+on, energy consumption and other expenses. We finally evaluate the performance of our method through experimental simulations. The experimental results show that this method has a significant effect on reducing the execution time of tasks and energy consumption of mobile devices.展开更多
Risk analysis of key systems have become a growing topic late of because of the development of offshore structures. Equipment failures of offioading system and fire accidents were analyzed based on the floating produc...Risk analysis of key systems have become a growing topic late of because of the development of offshore structures. Equipment failures of offioading system and fire accidents were analyzed based on the floating production, storage and offioading （FPSO） features. Fault tree analysis （FTA）, and failure modes and effects analysis （FMEA） methods were examined based on information already researched on modules of relex reliability studio （RRS）. Equipment failures were also analyzed qualitatively by establishing a fault tree and Boolean structure function based on the shortage of failure cases, statistical data, and risk control measures examined. Failure modes of fire accident were classified according to the different areas of fire occurrences during the FMEA process, using risk priority number （RPN） methods to evaluate their severity rank. The qualitative analysis of FTA gave the basic insight of forming the failure modes of FPSO offioading, and the fire FMEA gave the priorities and suggested processes. The research has practical importance for the security analysis problems of FPSO.展开更多
Mobile phones equipped with multiple wireless interfaces can increase their goodput performance by making use of concurrent transmissions over multiple paths, enabled by the Multipath TCP （MPTCP）. However, utilizing...Mobile phones equipped with multiple wireless interfaces can increase their goodput performance by making use of concurrent transmissions over multiple paths, enabled by the Multipath TCP （MPTCP）. However, utilizing MPTCP for data delivery may generally result in higher energy consumption, while the battery power of a mobile phone is limited. Thus, how to optimize the energy usage becomes very crucial and urgent. In this paper, we propose MPTCP-QE, a nov- el quality of experience （QoE）-driven energy-aware multipath content delivery approach for MPTCP-based mobile phones. The main idea of MPTCP-QE is described as follows： it first provides an application rate-aware energy-efficient subflow management strategy to tradeoff throughput performance and energy consumption for mobile phones; then uses an available bandwidth-aware congestion window fast recovery strategy to make a sender avoid unnecessary stow-start and utilize wireless resource quickly; and further introduces a novel receiver-driven energy-efficient SACK strategy to help a receiver possible to detect SACK loss timely and trigger loss recovery in a more energy-efficient way. The simulation results show that with the MPTCP-QE, the energy usage is enhanced while the performance level is maintained compared to existing MPTCP solutions.展开更多
Currently cellular networks do not have sufficient capacity to accommodate the exponential growth of mobile data requirements.Data can be delivered between mobile terminals through peer-to-peer WiFi communications(e.g...Currently cellular networks do not have sufficient capacity to accommodate the exponential growth of mobile data requirements.Data can be delivered between mobile terminals through peer-to-peer WiFi communications(e.g.WiFi direct),but contacts between mobile terminals are frequently disrupted because of the user mobility.In this paper,we propose a Subscribe-and-Send architecture and an opportunistic forwarding protocol for it called HPRO.Under Subscribe-and-Send,a user subscribes contents on the Content Service Provider(CSP) but does not download the subscribed contents.Some users who have these contents deliver them to the subscribers through WiFi opportunistic peer-to-peer communications.Numerical simulations provide a robust evaluation of the forwarding performance and the traffic offloading performance of Subscribe-and-Send and HPRO.展开更多
基金financially supported by the State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University(Grant No.HESS-1404)the National Natural Science Foundation of China(Grant No.51239007)
文摘The crashworthiness of the cargo containment systems （CCSs） of a floating liquid natural gas （FLNG） and the side structures in side-by-side offioading operations scenario are studied in this paper. An FLNG vessel is exposed to potential threats from collisions with a liquid natural gas carrier （LNGC） during the offioading operations, which has been confirmed by a model test of FLNG-LNGC side-by-side offioading operations. A nonlinear finite element code LS-DYNA is used to simulate the collision scenarios during the offioading operations. Finite element models of an FLNG vessel and an LNGC are established for the purpose of this study, including a detailed LNG cargo containment system in the FLNG side model. Based on the parameters obtained from the model test and potential dangerous accidents, typical collision scenarios are defined to conduct a comprehensive study. To evaluate the safety of the FLNG vessel, a limit state is proposed based on the structural responses of the LNG CCS. The different characteristics of the structural responses for the primary structural components, energy dissipation and collision forces are obtained for various scenarios. Deformation of the inner hull is found to have a great effect on the responses of the LNG CCS, with approximately 160 mm deformation corresponding to the limit state. Densely arranged web frames can absorb over 35% of the collision energy and be proved to greatly enhance the crashwo- rthiness of the FLNG side structures.
基金supported by the NSFC (61602126)the scientific and technological project of Henan province (162102210214)
文摘Fog computing is an emerging paradigm of cloud computing which to meet the growing computation demand of mobile application. It can help mobile devices to overcome resource constraints by offloading the computationally intensive tasks to cloud servers. The challenge of the cloud is to minimize the time of data transfer and task execution to the user, whose location changes owing to mobility, and the energy consumption for the mobile device. To provide satisfactory computation performance is particularly challenging in the fog computing environment. In this paper, we propose a novel fog computing model and offloading policy which can effectively bring the fog computing power closer to the mobile user. The fog computing model consist of remote cloud nodes and local cloud nodes, which is attached to wireless access infrastructure. And we give task offloading policy taking into account executi+on, energy consumption and other expenses. We finally evaluate the performance of our method through experimental simulations. The experimental results show that this method has a significant effect on reducing the execution time of tasks and energy consumption of mobile devices.
基金Supported by the Fundamental Research Funds for the Central Universities (HEUCFR1109)"111" projects foundation (Grant No.B07019) from State Administration of Foreign Experts Affairs of China and Ministry of Education of China
文摘Risk analysis of key systems have become a growing topic late of because of the development of offshore structures. Equipment failures of offioading system and fire accidents were analyzed based on the floating production, storage and offioading （FPSO） features. Fault tree analysis （FTA）, and failure modes and effects analysis （FMEA） methods were examined based on information already researched on modules of relex reliability studio （RRS）. Equipment failures were also analyzed qualitatively by establishing a fault tree and Boolean structure function based on the shortage of failure cases, statistical data, and risk control measures examined. Failure modes of fire accident were classified according to the different areas of fire occurrences during the FMEA process, using risk priority number （RPN） methods to evaluate their severity rank. The qualitative analysis of FTA gave the basic insight of forming the failure modes of FPSO offioading, and the fire FMEA gave the priorities and suggested processes. The research has practical importance for the security analysis problems of FPSO.
基金supported by the National Natural Science Foundation of China (NSFC) under Grant No. 61562044, 61262014the Natural Science Foundation of Jiangxi Province under Grant No. 20161BAB212046+2 种基金the Project of Soft Science Research Plan of Jiangxi Province under Grant No. 20161BBA10010the Science and Technology Research Project of Jiangxi Provincial Department of Education (GJJ150319)the Higher School Teaching Reform Research Subject of Jiangxi Province(JXJG-15-2-35)
文摘Mobile phones equipped with multiple wireless interfaces can increase their goodput performance by making use of concurrent transmissions over multiple paths, enabled by the Multipath TCP （MPTCP）. However, utilizing MPTCP for data delivery may generally result in higher energy consumption, while the battery power of a mobile phone is limited. Thus, how to optimize the energy usage becomes very crucial and urgent. In this paper, we propose MPTCP-QE, a nov- el quality of experience （QoE）-driven energy-aware multipath content delivery approach for MPTCP-based mobile phones. The main idea of MPTCP-QE is described as follows： it first provides an application rate-aware energy-efficient subflow management strategy to tradeoff throughput performance and energy consumption for mobile phones; then uses an available bandwidth-aware congestion window fast recovery strategy to make a sender avoid unnecessary stow-start and utilize wireless resource quickly; and further introduces a novel receiver-driven energy-efficient SACK strategy to help a receiver possible to detect SACK loss timely and trigger loss recovery in a more energy-efficient way. The simulation results show that with the MPTCP-QE, the energy usage is enhanced while the performance level is maintained compared to existing MPTCP solutions.
基金supported by the National Natural Science Foundation of China under Grants No. 61100208,No. 61100205the Natural Science Foundation of Jiangsu Province under Grant No. BK2011169+1 种基金the Foundation of Beijing University of Posts and Telecommunications under Grant No. 2013RC0309supported by the EU FP7 Project REC-OGNITION:Relevance and Cognition for SelfAwareness in a Content-Centric Internet
文摘Currently cellular networks do not have sufficient capacity to accommodate the exponential growth of mobile data requirements.Data can be delivered between mobile terminals through peer-to-peer WiFi communications(e.g.WiFi direct),but contacts between mobile terminals are frequently disrupted because of the user mobility.In this paper,we propose a Subscribe-and-Send architecture and an opportunistic forwarding protocol for it called HPRO.Under Subscribe-and-Send,a user subscribes contents on the Content Service Provider(CSP) but does not download the subscribed contents.Some users who have these contents deliver them to the subscribers through WiFi opportunistic peer-to-peer communications.Numerical simulations provide a robust evaluation of the forwarding performance and the traffic offloading performance of Subscribe-and-Send and HPRO.
