Admission control is a key mechanism to manage the increasing number of the simultaneous demanding services, requiring a desired Quality of Service(QoS) in a spectrum efficient manner. To address this issue,we investi...Admission control is a key mechanism to manage the increasing number of the simultaneous demanding services, requiring a desired Quality of Service(QoS) in a spectrum efficient manner. To address this issue,we investigate in this work, the use of the superposition coding technique to increase the system capacity through multiuser diversity exploitation. We propose a novel joint admission control and superposition coding formalism based on different utility functions:Opportunistic(OPSC), Great Fairness(GFSC)and Proportional Fairness(PFSC). Simulation results show the superiority of our proposed approaches over other by providing higher mean of served VoIP users and higher throughput while maintaining an average VoIP packet transmission delay lower than 0.6 ms.展开更多
Design of rib support systems in U.S. coal mines is based primarily on local practices and experience. A better understanding of current rib support practices in U.S. coal mines is crucial for developing a sound engin...Design of rib support systems in U.S. coal mines is based primarily on local practices and experience. A better understanding of current rib support practices in U.S. coal mines is crucial for developing a sound engineering rib support design tool. The objective of this paper is to analyze the current practices of rib control in U.S. coal mines. Twenty underground coal mines were studied representing various coal basins,coal seams,geology,loading conditions,and rib control strategies. The key findings are:(1) any rib design guideline or tool should take into account external rib support as well as internal bolting;(2) rib bolts on their own cannot contain rib spall,especially in soft ribs subjected to significant load—external rib control devices such as mesh are required in such cases to contain rib sloughing;(3) the majority of the studied mines follow the overburden depth and entry height thresholds recommended by the Program Information Bulletin 11-29 issued by the Mine Safety and Health Administration;(4) potential rib instability occurred when certain geological features prevailed—these include draw slate and/or bone coal near the rib/roof line,claystone partings,and soft coal bench overlain by rock strata;(5) 47% of the studied rib spall was classified as blocky—this could indicate a high potential of rib hazards; and(6) rib injury rates of the studied mines for the last three years emphasize the need for more rib control management for mines operating at overburden depths between 152.4 m and 304.8 m.展开更多
Complex cyber-physical network refers to a new generatio~ of complex networks whose normal functioning significantly relies on tight interactions between its physical and cyber compo- nents. Many modern critical infra...Complex cyber-physical network refers to a new generatio~ of complex networks whose normal functioning significantly relies on tight interactions between its physical and cyber compo- nents. Many modern critical infrastructures can be appropriately modelled as complex cyber-physical networks. Typical examples of such infrastructures are electrical power grids, WWW, public trans- portation systems, state financial networks, and the Interact. These critical facilities play important roles in ensuring the stability of society as well as the development of economy. Advances in informa- tion and communication technology open opportunities for malicious attackers to launch coordinated attacks on cyber-physical critical facilities in networked infrastructures from any Interact-accessible place. Cybersecurity of complex cyber-physical networks has emerged as a hot topic within this con- text. In practice, it is also very crucial to understand the interplay between the evolution of underlying network structures and the collective dynamics on these complex networks and consequently to design efficient security control strategies to protect the evolution of these networks. In this paper, cybersecu- rity of complex cyber-physical networks is first outlined and then some security enhancing techniques, with particular emphasis on safety communications, attack detection and fault-tolerant control, are suggested. Furthermore, a new class of efficient secure the achievement of desirable pinning synchronization control strategies are proposed for guaranteeing behaviors in complex cyber-physical networks against malicious attacks on nodes. The authors hope that this paper motivates to design enhanced security strategies for complex cyber-physical network systems, to realize resilient and secure critical infrastructures.展开更多
文摘Admission control is a key mechanism to manage the increasing number of the simultaneous demanding services, requiring a desired Quality of Service(QoS) in a spectrum efficient manner. To address this issue,we investigate in this work, the use of the superposition coding technique to increase the system capacity through multiuser diversity exploitation. We propose a novel joint admission control and superposition coding formalism based on different utility functions:Opportunistic(OPSC), Great Fairness(GFSC)and Proportional Fairness(PFSC). Simulation results show the superiority of our proposed approaches over other by providing higher mean of served VoIP users and higher throughput while maintaining an average VoIP packet transmission delay lower than 0.6 ms.
文摘Design of rib support systems in U.S. coal mines is based primarily on local practices and experience. A better understanding of current rib support practices in U.S. coal mines is crucial for developing a sound engineering rib support design tool. The objective of this paper is to analyze the current practices of rib control in U.S. coal mines. Twenty underground coal mines were studied representing various coal basins,coal seams,geology,loading conditions,and rib control strategies. The key findings are:(1) any rib design guideline or tool should take into account external rib support as well as internal bolting;(2) rib bolts on their own cannot contain rib spall,especially in soft ribs subjected to significant load—external rib control devices such as mesh are required in such cases to contain rib sloughing;(3) the majority of the studied mines follow the overburden depth and entry height thresholds recommended by the Program Information Bulletin 11-29 issued by the Mine Safety and Health Administration;(4) potential rib instability occurred when certain geological features prevailed—these include draw slate and/or bone coal near the rib/roof line,claystone partings,and soft coal bench overlain by rock strata;(5) 47% of the studied rib spall was classified as blocky—this could indicate a high potential of rib hazards; and(6) rib injury rates of the studied mines for the last three years emphasize the need for more rib control management for mines operating at overburden depths between 152.4 m and 304.8 m.
基金supported by the National Key Research and Development Program of China under Grant No.2016YFB0800401the National Nature Science Foundation of China under Grant Nos.61304168,61673104,and 61322302+3 种基金the Natural Science Foundation of Jiangsu Province of China under Grant No.BK20130595the National Ten Thousand Talent Program for Young Top-Notch Talents,the Six Talent Peaks of Jiangsu Province of China under Grant No.2014-DZXX-004the Doctoral Program of Higher Education of China under Grant No.20130092120030the Fundamental Research Funds for the Central Universities of China under Grant No.2242016K41030
文摘Complex cyber-physical network refers to a new generatio~ of complex networks whose normal functioning significantly relies on tight interactions between its physical and cyber compo- nents. Many modern critical infrastructures can be appropriately modelled as complex cyber-physical networks. Typical examples of such infrastructures are electrical power grids, WWW, public trans- portation systems, state financial networks, and the Interact. These critical facilities play important roles in ensuring the stability of society as well as the development of economy. Advances in informa- tion and communication technology open opportunities for malicious attackers to launch coordinated attacks on cyber-physical critical facilities in networked infrastructures from any Interact-accessible place. Cybersecurity of complex cyber-physical networks has emerged as a hot topic within this con- text. In practice, it is also very crucial to understand the interplay between the evolution of underlying network structures and the collective dynamics on these complex networks and consequently to design efficient security control strategies to protect the evolution of these networks. In this paper, cybersecu- rity of complex cyber-physical networks is first outlined and then some security enhancing techniques, with particular emphasis on safety communications, attack detection and fault-tolerant control, are suggested. Furthermore, a new class of efficient secure the achievement of desirable pinning synchronization control strategies are proposed for guaranteeing behaviors in complex cyber-physical networks against malicious attacks on nodes. The authors hope that this paper motivates to design enhanced security strategies for complex cyber-physical network systems, to realize resilient and secure critical infrastructures.
