Analysis on the “Robust Yet Fragile” Nature of Internet: Load, Capacity and the Cascading Failure Avalanche Effect

Author(s):  
Chi Guo ◽  
Lina Wang ◽  
Furong Zhou ◽  
Lainv Huang ◽  
Zhen Peng
2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Haiyan Han ◽  
Rennong Yang

Many real-world systems can be depicted as interdependent networks and they usually show an obvious property of asymmetry. Furthermore, node or edge failure can trigger load redistribution which leads to a cascade of failure in the whole network. In order to deeply investigate the load-induced cascading failure, firstly, an asymmetrical model of interdependent network consisting of a hierarchical weighted network and a WS small-world network is constructed. Secondly, an improved “load-capacity” model is applied for node failure and edge failure, respectively, followed by a series of simulations of cascading failure over networks in both interdependent and isolated statuses. The simulation results prove that the robustness in isolated network changes more promptly than that in the interdependent one. Network robustness is positively related to “capacity,” but negatively related to “load.” The hierarchical weight structure in the subnetwork leads to a “plateau” phenomenon in the progress of cascading failure.


IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 7993-8003 ◽  
Author(s):  
Yue Yang ◽  
Baofeng Sun ◽  
Shaohua Wang ◽  
Yongxing Li ◽  
Xiaoni Li

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Jiajun Huang ◽  
Feng Zhou ◽  
Mengru Xi

The load capacity of urban rail transit station is of great significance to provide reference in station design and operation management. However, it is difficult to carry out quantitative calculation quickly and accurately due to the complex interaction among passenger behaviors, facility layout, and the limit capacity of single facility. In this paper, the association network of facilities is set up based on the analysis of passenger service chain in station. Then the concept of cascading failure is introduced to the dynamic calculation model of load capacity, which is established on the user-equilibrium allocation model. The solution algorithm is optimized with node attack strategy of complex network to effectively reduce the computational complexity. Finally, a case study of Lujiabang Road Station in Shanghai is carried out and compared with the simulation results of StaPass, verifying the feasibility of this approach. The proposed method can not only search for the bottleneck of capacity, but also help to trace the loading variation of facilities network in different scenarios, providing theoretical supports on passenger flow organization.


2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Zhaoyang Qu ◽  
Yunchang Dong ◽  
Nan Qu ◽  
Lei Wang ◽  
Yang Li ◽  
...  

The scale of the electric cyber physical system (ECPS) is continuously extending, and the existing cascade failure models ignore both the information flow and power flow transferring characteristics and also lack effective survivability analysis. In this paper, the quantitative evaluation method for cascading failure of ECPS survivability considering optimal load allocation is proposed. Firstly, according to the system topological structure and correlation, the degree-betweenness weighted correlation matrix of ECPS is established by defining the degree function as well as the electric betweenness, and the formal representation of coupled ECPS network model is realized. Secondly, based on the structural connectivity change and risk propagation range of ECPS cascade failure, the survivability evaluation model is designed by taking into account the constraints such as node load capacity limitation, information flow optimal allocation strategy, power flow optimization equation, and system safety operation. Finally, the firefly algorithm with chaotic Lévy flight is proposed to solve the evaluation model efficiently. The case study vividly shows that the evaluation method can effectively quantify the survivability of ECPS and thus enhance the evaluation efficiency of large-scale coupled systems.


Author(s):  
Dennis Flanagan ◽  
Alessandro Fisher BS ◽  
Carmen Ciardiello ◽  
Vito Moreno ◽  
Alen Uvalic ◽  
...  

When planning an implant supported restoration the dentist is faced with the surgical and prosthetic technical issues as well as the patient’s expectations. Many patients wish an immediate solution to an edentulous condition. This is especially may be true in the esthetic zone. The extent of the zone is determined by the patient. The dentist may consider when it is feasible to load the supporting implants with definitive or provisional prosthetics. For the work herein, consideration of many parameters were theoretically assessed for inclusion: bone density, cortical thickness, seating torque, parafunction, bite load capacity, number of implants under load, implant/crown ratio, implant diameter and length. After assessment, the most influential parameters were selected. An iteration, using patient age, implant diameter, bite load capacity and cortical thickness, is now presented to aid the implant dentist in determining the feasibility for immediate functional loading of a just placed dental implant in a healed site. Extensive testing is required to develop this concept. According to this iteration, most immediate functional loaded implants would fail. A future refined and definitive formula may enable the clinician to safely immediately functional load an implant with a definitive prosthesis.


2018 ◽  
Vol 9 (5) ◽  
pp. 174
Author(s):  
Agus Maryoto ◽  
Han Ay Lie ◽  
Nanang Gunawan Wariyatno

2020 ◽  
Vol 40 (11) ◽  
pp. 905-907
Author(s):  
V. I. Korotkin ◽  
E. M. Kolosova ◽  
N. P. Onishkov
Keyword(s):  

Author(s):  
Nicholas Haritos ◽  
Anil Hira ◽  
Priyan Mendis ◽  
Rob Heywood ◽  
Armando Giufre

VicRoads, the road authority for the state of Victoria, Australia, has been undertaking extensive research into the load capacity and performance of cast-in-place reinforced concrete flat slab bridges. One of the key objectives of this research is the development of analytical tools that can be used to better determine the performance of these bridges under loadings to the elastic limit and subsequently to failure. The 59-year-old Barr Creek Bridge, a flat slab bridge of four short continuous spans over column piers, was made available to VicRoads in aid of this research. The static testing program executed on this bridge was therefore aimed at providing a comprehensive set of measurements of its response to serviceability level loadings and beyond. This test program was preceded by the performance of a dynamic test (a simplified experimental modal analysis using vehicular excitation) to establish basic structural properties of the bridge (effective flexural rigidity, EI) and the influence of the abutment supports from identification of its dynamic modal characteristics. The dynamic test results enabled a reliably tuned finite element model of the bridge in its in-service condition to be produced for use in conjunction with the static testing program. The results of the static testing program compared well with finite element modeling predictions in both the elastic range (serviceability loadings) and the nonlinear range (load levels taken to incipient collapse). Observed collapse failure modes and corresponding collapse load levels were also found to be predicted well using yield line theory.


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