In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper...In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper, we present a state-based channel capacity perception scheme to provide statistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wireless multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capacity, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a network resource and forwards the data packet by taking into consideration the channel capacity deployments in multi-terminal or multi-hop mesh networks. Extensive computer simulations demonstrate that the proposed scheme can achieve better performance in terms of packet delivery ratio and network throughput compared to the existing capacity prediction schemes.展开更多
Few studies have analyzed climate change perceptions in the disaster risk management sector.This research aimed to understand how civil defense experts are dealing with the climate change topic:what they learn and thi...Few studies have analyzed climate change perceptions in the disaster risk management sector.This research aimed to understand how civil defense experts are dealing with the climate change topic:what they learn and think about.An online survey was conducted between October and December 2021 with 1,063 participants from civil defense agencies in Brazil.The findings indicate:(1) most(80.6%) civil defense officers completely agreed that climate change will cause additional challenges to disaster risk management,while 10.1% stated that they are prepared to deal with it;(2) one quarter of the respondents(26.3%) completely agreed that they easily understand the information about climate change,but trust in the sources of information is a challenge-52.4% completely agreed and 40.5% partially agreed with information provided by scientists,but the levels of trust were reduced when referring to governments and press;and(3) about 30% of the respondents thought that civil defense work is associated with the Sustainable Development Goals(SDGs),despite SDGs 11 and 13 being related to disasters and climate change.The identification of civil defense’ perceptions on climate change is an important step in seeking pathways for increasing capacity building to achieve disaster risk reduction and climate change adaptation.展开更多
基金supported by the National Natural Science Foundation of China under Grants No.60972038,No.61001077,No.61101105 the Scientific Research Foundation for Nanjing University of Posts and Telecommunications under Grant No.NY211007+2 种基金 the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University under Grant No.2011D05 Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20113223120002 University Natural Science Research Project of Jiangsu Province under Grant No.11KJB510016
文摘In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper, we present a state-based channel capacity perception scheme to provide statistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wireless multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capacity, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a network resource and forwards the data packet by taking into consideration the channel capacity deployments in multi-terminal or multi-hop mesh networks. Extensive computer simulations demonstrate that the proposed scheme can achieve better performance in terms of packet delivery ratio and network throughput compared to the existing capacity prediction schemes.
基金The authors acknowledge the state and municipal civil defense personnel in Brazil.Victor Marchezini acknowledges the São Paulo Research Foundation-Fapesp(Grant Number 2018/06093-4)JoséA.Marengo thanks the support of the National Institute of Science and Technology for Climate Change Phase 2 under CNPq Grant 465501/2014-1+1 种基金FAPESP Grants 2014/50848-9the National Coordination for Higher Education and Training(CAPES)Grant 88887.136402-00INCT.
文摘Few studies have analyzed climate change perceptions in the disaster risk management sector.This research aimed to understand how civil defense experts are dealing with the climate change topic:what they learn and think about.An online survey was conducted between October and December 2021 with 1,063 participants from civil defense agencies in Brazil.The findings indicate:(1) most(80.6%) civil defense officers completely agreed that climate change will cause additional challenges to disaster risk management,while 10.1% stated that they are prepared to deal with it;(2) one quarter of the respondents(26.3%) completely agreed that they easily understand the information about climate change,but trust in the sources of information is a challenge-52.4% completely agreed and 40.5% partially agreed with information provided by scientists,but the levels of trust were reduced when referring to governments and press;and(3) about 30% of the respondents thought that civil defense work is associated with the Sustainable Development Goals(SDGs),despite SDGs 11 and 13 being related to disasters and climate change.The identification of civil defense’ perceptions on climate change is an important step in seeking pathways for increasing capacity building to achieve disaster risk reduction and climate change adaptation.
