In the face of disasters,a strong organizational network is the foundation for eff ectively accomplishing emergency relief tasks.In an emergency response network comprising tasks and organizations,the failure of certa...In the face of disasters,a strong organizational network is the foundation for eff ectively accomplishing emergency relief tasks.In an emergency response network comprising tasks and organizations,the failure of certain organizations may cause large systemic losses owing to internal component associations.To analyze the response system’s robustness,we developed emergency response networks based on the associations between organizations and tasks.A cascading failure model was established considering task reassignment after organizational failure,and indicators in terms of tasks and structures were identified to observe robustness.In the proposed model,we developed random,bond-based,and bridge-based organizational failure modes,and average,capacity-based,and surplus-based reassignment programs.To validate the model,simulation experiments were conducted in the context of extreme rainstorms.The results show that bridge-based failures were the most damaging to network systems,and the average reassignment program was the least eff ective.The analysis of model parameters illustrates the critical eff ectiveness of individual organizational capability in enhancing system robustness.The proposed framework and model enrich the study of emergency response networks with favorable applicability,and the results can provide theoretical references for emergency management practices.展开更多
Meteor Burst Communication(MBC),a niche yet revolutionary wireless communication paradigm,exploits the transient ionized trails generated by meteors ablating in Earth’s atmosphere to enable sporadic yet resilient lon...Meteor Burst Communication(MBC),a niche yet revolutionary wireless communication paradigm,exploits the transient ionized trails generated by meteors ablating in Earth’s atmosphere to enable sporadic yet resilient long-distance radio links.Known for its exceptional resilience,robustness,and sustained connectivity,MBC holds significant promise for applications in emergency communications,remote area connectivity,military/defense systems,and environmental monitoring.However,the scientific exploration and application of MBC have long been highly challenging.In particular,under the combined influence of multiple physical field factors,the channel experiences superimposed multiple random fading effects,exhibiting bursty,highly time-varying,and strongly random characteristics.This persistent technical challenge has resulted in the absence of a practical statistical channel model for MBC to date.展开更多
Emergency road networks(ERNs),an important part of local disaster prevention systems,can provide security to residents and their property.Exploring the ERNs structure is of great significance in terms of promoting dis...Emergency road networks(ERNs),an important part of local disaster prevention systems,can provide security to residents and their property.Exploring the ERNs structure is of great significance in terms of promoting disaster prevention and establishing road safety in dangerous mountainous areas.This study considered the ERNs of the Kangding section of the Dadu River Basin as the area for a case study.Complex Network Analysis was used to examine the relationship between the four characteristic indicators of mountain roads and the degree of earthquake impacts under the Lushan,Wenchuan,and Kangding Earthquake scenarios.Based on the analysis results,the southwest mountain road network was evaluated;then,computer simulations were used to evaluate the structural changes in the road network after index changes.The network was optimized,and the corresponding emergency avoidance network was proposed to provide a reference for the establishment of the mountainous ERN.The results show that the overall completeness of the mountainous ERNs in Southwest China is poor and prone to traffic accidents.Moreover,the local stability is poor,and the network is susceptible to natural hazards.The overall structure of the road network is balanced,but that of certain road sections is not.Road sections with different attributes present a“gathering-scattering”spatial distribution,i.e,some sections are clustered together while others are far apart.Accordingly,a planning optimization strategy is proposed to better understand the complexity and systematic nature of the mountainous ERN as a whole and to provide a reference for disaster prevention and mitigation planning in mountainous regions in Southwest China.展开更多
The efficiency of post-disaster relief operations is impacted by the design of the emergency supply networks in the earthquake preparedness phase.This paper proposes a bi-objective mixed integer programming model to i...The efficiency of post-disaster relief operations is impacted by the design of the emergency supply networks in the earthquake preparedness phase.This paper proposes a bi-objective mixed integer programming model to improve the preparedness of the emergency supply network.The maximization of connectivity reliability and relief is taken as the objective function as the design perspectives were inclined towards prioritizing human survival over cost.The number and location of storage points,the preset level and the prematching of demand nodes with their supply storage points are determined based on this.Then,applicability is evaluated through numerical examples,and critical parameters are demonstrated by sensitivity analysis.Finally,practicality is evaluated through practical examples.The results demonstrate that the method in this paper designs an emergency supply network with high reliability and relief level.The reliability of the supply network is improved by 42.3%and the rescue level reaches 96.6%compared with the preoptimization period.Results may provide theoretical support for urban pre-earthquake preparedness and can help traffic planners and local governments formulate better earthquake prevention strategies.展开更多
Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication networks.Unmanned aerial vehicles(UAVs),which are with a high flexibility,can be employ...Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication networks.Unmanned aerial vehicles(UAVs),which are with a high flexibility,can be employed as temporary base stations to establish emergency networks.To relieve the backhaul burden of UAVs,some imperative contents can be cached by terrestrial cache-enabled rescuers(CERs)and provide for victims with device-to-device(D2D)transmissions.To support the effectiveness and timeliness of emergency communication,the delay-bounded quality-of-service(QoS)requirement and network throughput are desired to be comprehensively considered,which imposes a new challenge for caching placement and CER deployment.In this paper,we focus on joint caching placement and CER deployment to maximize the effective capacity subject to delay-bounded QoS requirement.The overall non-convex problem is transformed into the caching placement and the CER deployment sub-problems.Then,we develop the QoS-aware caching placement scheme with fixed CER deployment density and obtain the QoS-aware CER deployment density with fixed caching placement.Based on the block-coordinate descent method,we also propose the joint caching placement and CER deployment scheme,which can not only effectively enhance average effective capacity but also guarantee the delay-bounded QoS requirement.Also,numerical simulations are conducted to show the performances of the proposed schemes.展开更多
Public communication infrastructures are susceptible to disasters. Thus, the Emergency Communication Networks(ECNs) of small groups are necessary to maintain real-time communication during disasters. Given that ECNs a...Public communication infrastructures are susceptible to disasters. Thus, the Emergency Communication Networks(ECNs) of small groups are necessary to maintain real-time communication during disasters. Given that ECNs are self-built by users, the unavailability of infrastructures and the openness of wireless channels render them insecure. ECN security, however, is a rarely studied issue despite of its importance. Here, we propose a security scheme for the ECNs of small groups. Our scheme is based on the optimized Byzantine Generals’ Problem combined with the analysis of trusted security problems in ECNs. Applying the Byzantine Generals’ Problem to ECNs is a novel approach to realize two new functions, debugging and error correction, for ensuring system consistency and accuracy. Given the limitation of terminal devices, the lightweight fast ECDSA algorithm is introduced to guarantee the integrity and security of communication and the efficiency of the network. We implement a simulation to verify the feasibility of the algorithm after theoretical optimization.展开更多
The rapid growth of deep learning applications has sparked a revolution in computing paradigms,with optical neural networks(ONNs)emerging as a promising platform for achieving ultra-high computing power and energy eff...The rapid growth of deep learning applications has sparked a revolution in computing paradigms,with optical neural networks(ONNs)emerging as a promising platform for achieving ultra-high computing power and energy efficiency.Despite great progress in analog optical computing,the lack of scalable optical nonlinearities and losses in photonic devices pose considerable challenges for power levels,energy efficiency,and signal latency.Here,we report an end-to-end all-optical nonlinear activator that utilizes the energy conversion of Brillouin scattering to perform efficient nonlinear processing.The activator exhibits an ultra-low activation threshold(24 nW),a wide transmission bandwidth(over 40 GHz),strong robustness,and high energy transfer efficiency.These advantages provide a feasible solution to overcome the existing bottlenecks in ONNs.As a proof-of-concept,a series of tasks is designed to validate the capability of the proposed activator as an activation unit for ONNs.Simulations show that the experiment-based nonlinear model outperforms classical activation functions in classification(97.64%accuracy for MNIST and 87.84%for Fashion-MNIST)and regression(with a symbol error rate as low as 0%)tasks.This work provides valuable insights into the innovative design of all-optical neural networks.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.72504070,72404024)。
文摘In the face of disasters,a strong organizational network is the foundation for eff ectively accomplishing emergency relief tasks.In an emergency response network comprising tasks and organizations,the failure of certain organizations may cause large systemic losses owing to internal component associations.To analyze the response system’s robustness,we developed emergency response networks based on the associations between organizations and tasks.A cascading failure model was established considering task reassignment after organizational failure,and indicators in terms of tasks and structures were identified to observe robustness.In the proposed model,we developed random,bond-based,and bridge-based organizational failure modes,and average,capacity-based,and surplus-based reassignment programs.To validate the model,simulation experiments were conducted in the context of extreme rainstorms.The results show that bridge-based failures were the most damaging to network systems,and the average reassignment program was the least eff ective.The analysis of model parameters illustrates the critical eff ectiveness of individual organizational capability in enhancing system robustness.The proposed framework and model enrich the study of emergency response networks with favorable applicability,and the results can provide theoretical references for emergency management practices.
文摘Meteor Burst Communication(MBC),a niche yet revolutionary wireless communication paradigm,exploits the transient ionized trails generated by meteors ablating in Earth’s atmosphere to enable sporadic yet resilient long-distance radio links.Known for its exceptional resilience,robustness,and sustained connectivity,MBC holds significant promise for applications in emergency communications,remote area connectivity,military/defense systems,and environmental monitoring.However,the scientific exploration and application of MBC have long been highly challenging.In particular,under the combined influence of multiple physical field factors,the channel experiences superimposed multiple random fading effects,exhibiting bursty,highly time-varying,and strongly random characteristics.This persistent technical challenge has resulted in the absence of a practical statistical channel model for MBC to date.
基金jointly supported by the National Key R&D Program of China(2018YFD1100804)。
文摘Emergency road networks(ERNs),an important part of local disaster prevention systems,can provide security to residents and their property.Exploring the ERNs structure is of great significance in terms of promoting disaster prevention and establishing road safety in dangerous mountainous areas.This study considered the ERNs of the Kangding section of the Dadu River Basin as the area for a case study.Complex Network Analysis was used to examine the relationship between the four characteristic indicators of mountain roads and the degree of earthquake impacts under the Lushan,Wenchuan,and Kangding Earthquake scenarios.Based on the analysis results,the southwest mountain road network was evaluated;then,computer simulations were used to evaluate the structural changes in the road network after index changes.The network was optimized,and the corresponding emergency avoidance network was proposed to provide a reference for the establishment of the mountainous ERN.The results show that the overall completeness of the mountainous ERNs in Southwest China is poor and prone to traffic accidents.Moreover,the local stability is poor,and the network is susceptible to natural hazards.The overall structure of the road network is balanced,but that of certain road sections is not.Road sections with different attributes present a“gathering-scattering”spatial distribution,i.e,some sections are clustered together while others are far apart.Accordingly,a planning optimization strategy is proposed to better understand the complexity and systematic nature of the mountainous ERN as a whole and to provide a reference for disaster prevention and mitigation planning in mountainous regions in Southwest China.
基金supported by the National Natural Science Foundation of China(Grants No.52372302 and 52172304)the Key Funding Project of Hebei Provincial Department of Science and Technology(Grant No.22370801D).
文摘The efficiency of post-disaster relief operations is impacted by the design of the emergency supply networks in the earthquake preparedness phase.This paper proposes a bi-objective mixed integer programming model to improve the preparedness of the emergency supply network.The maximization of connectivity reliability and relief is taken as the objective function as the design perspectives were inclined towards prioritizing human survival over cost.The number and location of storage points,the preset level and the prematching of demand nodes with their supply storage points are determined based on this.Then,applicability is evaluated through numerical examples,and critical parameters are demonstrated by sensitivity analysis.Finally,practicality is evaluated through practical examples.The results demonstrate that the method in this paper designs an emergency supply network with high reliability and relief level.The reliability of the supply network is improved by 42.3%and the rescue level reaches 96.6%compared with the preoptimization period.Results may provide theoretical support for urban pre-earthquake preparedness and can help traffic planners and local governments formulate better earthquake prevention strategies.
基金This work was supported in part by National Natural Science Foundation of China(Nos.61771368 and 61671347)the Young Elite Scientists Sponsorship Program by CAST(No.2016QNRC001)+1 种基金the Youth Talent Support Fund of Science and Technology of Shaanxi Province(No.2018KJXX-025)Part of this work has been accepted by the IEEE Conference on Computer Communications Workshops(INFOCOM Workshop on Intelligent Wireless Emergency Communications Networks),Toronto,Canada,2020[1].
文摘Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication networks.Unmanned aerial vehicles(UAVs),which are with a high flexibility,can be employed as temporary base stations to establish emergency networks.To relieve the backhaul burden of UAVs,some imperative contents can be cached by terrestrial cache-enabled rescuers(CERs)and provide for victims with device-to-device(D2D)transmissions.To support the effectiveness and timeliness of emergency communication,the delay-bounded quality-of-service(QoS)requirement and network throughput are desired to be comprehensively considered,which imposes a new challenge for caching placement and CER deployment.In this paper,we focus on joint caching placement and CER deployment to maximize the effective capacity subject to delay-bounded QoS requirement.The overall non-convex problem is transformed into the caching placement and the CER deployment sub-problems.Then,we develop the QoS-aware caching placement scheme with fixed CER deployment density and obtain the QoS-aware CER deployment density with fixed caching placement.Based on the block-coordinate descent method,we also propose the joint caching placement and CER deployment scheme,which can not only effectively enhance average effective capacity but also guarantee the delay-bounded QoS requirement.Also,numerical simulations are conducted to show the performances of the proposed schemes.
文摘Public communication infrastructures are susceptible to disasters. Thus, the Emergency Communication Networks(ECNs) of small groups are necessary to maintain real-time communication during disasters. Given that ECNs are self-built by users, the unavailability of infrastructures and the openness of wireless channels render them insecure. ECN security, however, is a rarely studied issue despite of its importance. Here, we propose a security scheme for the ECNs of small groups. Our scheme is based on the optimized Byzantine Generals’ Problem combined with the analysis of trusted security problems in ECNs. Applying the Byzantine Generals’ Problem to ECNs is a novel approach to realize two new functions, debugging and error correction, for ensuring system consistency and accuracy. Given the limitation of terminal devices, the lightweight fast ECDSA algorithm is introduced to guarantee the integrity and security of communication and the efficiency of the network. We implement a simulation to verify the feasibility of the algorithm after theoretical optimization.
基金National Key Research and Development Program of China(2021YFA1401100)Innovation Group Project of Sichuan Province(20CXTD0090)。
文摘The rapid growth of deep learning applications has sparked a revolution in computing paradigms,with optical neural networks(ONNs)emerging as a promising platform for achieving ultra-high computing power and energy efficiency.Despite great progress in analog optical computing,the lack of scalable optical nonlinearities and losses in photonic devices pose considerable challenges for power levels,energy efficiency,and signal latency.Here,we report an end-to-end all-optical nonlinear activator that utilizes the energy conversion of Brillouin scattering to perform efficient nonlinear processing.The activator exhibits an ultra-low activation threshold(24 nW),a wide transmission bandwidth(over 40 GHz),strong robustness,and high energy transfer efficiency.These advantages provide a feasible solution to overcome the existing bottlenecks in ONNs.As a proof-of-concept,a series of tasks is designed to validate the capability of the proposed activator as an activation unit for ONNs.Simulations show that the experiment-based nonlinear model outperforms classical activation functions in classification(97.64%accuracy for MNIST and 87.84%for Fashion-MNIST)and regression(with a symbol error rate as low as 0%)tasks.This work provides valuable insights into the innovative design of all-optical neural networks.
