scholarly journals Where to cut to delay a pandemic with minimum disruption? mathematical analysis based on the SIS model

2021 ◽  
pp. 1-26
Author(s):  
Paolo Bartesaghi ◽  
Ernesto Estrada
Keyword(s):  
Upper Bound ◽  
Time Delays ◽  
Transportation Network ◽  
Network Capacity ◽  
Sis Model ◽  
Transportation Capacity ◽  
Epidemic Dynamic ◽  
Dynamic Relations ◽  
The Uk ◽  
Communicability Function

We consider the problem of modifying a network topology in such a way as to delay the propagation of a disease with minimal disruption of the network capacity to reroute goods/items/passengers. We find an approximate solution to the Susceptible-Infected-Susceptible (SIS) model, which constitutes an upper bound to its exact solution. This upper bound allows direct structure-epidemic dynamic relations via the total communicability function. Using this approach we propose a strategy to remove edges in a network that significantly delays the propagation of a disease across the network with minimal disruption of its capacity to deliver goods/items/passengers. We apply this strategy to the analysis of the UK airport transportation network weighted by the number of passengers transported in 2003. We find that the removal of all flights connecting four origin-destination pairs in the UK delays the propagation of a disease by more than 300%, with a minimal deterioration of the transportation capacity of this network. These time delays in the propagation of a disease represent an important non-pharmaceutical intervention to confront an epidemic, allowing for better preparations of the health systems, while keeping the economy moving with minimal disruptions.

scholarly journals Delay-Dependent Robust Stabilization for Nonlinear Large Systems via Decentralized Fuzzy Control

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Chun-xia Dou ◽  
Zhi-sheng Duan ◽  
Xing-bei Jia ◽  
Xiao-gang Li ◽  
Jin-zhao Yang ◽  
...  
Keyword(s):  
Time Delay ◽  
Fuzzy Control ◽  
Upper Bound ◽  
Time Delays ◽  
Sufficient Conditions ◽  
Large System ◽  
Disturbance Attenuation ◽  
Robust Controller ◽  
Large Systems ◽  
Delay Dependent

A delay-dependent robust fuzzy control approach is developed for a class of nonlinear uncertain interconnected time delay large systems in this paper. First, an equivalent T–S fuzzy model is extended in order to accurately represent nonlinear dynamics of the large system. Then, a decentralized state feedback robust controller is proposed to guarantee system stabilization with a prescribedH∞disturbance attenuation level. Furthermore, taking into account the time delays in large system, based on a less conservative delay-dependent Lyapunov function approach combining with linear matrix inequalities (LMI) technique, some sufficient conditions for the existence ofH∞robust controller are presented in terms of LMI dependent on the upper bound of time delays. The upper bound of time-delay and minimizedH∞performance index can be obtained by using convex optimization such that the system can be stabilized and for all time delays whose sizes are not larger than the bound. Finally, the effectiveness of the proposed controller is demonstrated through simulation example.

scholarly journals Estimating the Capacity of Urban Transportation Networks with an Improved Sensitivity Based Method

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Muqing Du ◽  
Xiaowei Jiang ◽  
Lin Cheng
Keyword(s):  
Sensitivity Analysis ◽  
Large Scale ◽  
Transportation Network ◽  
Network Capacity ◽  
Combined Model ◽  
Practical Applications ◽  
Large Scale Problems ◽  
Capacity Model ◽  
High Efficient ◽  
Equilibrium Constraint

The throughput of a given transportation network is always of interest to the traffic administrative department, so as to evaluate the benefit of the transportation construction or expansion project before its implementation. The model of the transportation network capacity formulated as a mathematic programming with equilibrium constraint (MPEC) well defines this problem. For practical applications, a modified sensitivity analysis based (SAB) method is developed to estimate the solution of this bilevel model. The high-efficient origin-based (OB) algorithm is extended for the precise solution of the combined model which is integrated in the network capacity model. The sensitivity analysis approach is also modified to simplify the inversion of the Jacobian matrix in large-scale problems. The solution produced in every iteration of SAB is restrained to be feasible to guarantee the success of the heuristic search. From the numerical experiments, the accuracy of the derivatives for the linear approximation could significantly affect the converging of the SAB method. The results also show that the proposed method could obtain good suboptimal solutions from different starting points in the test examples.

scholarly journals Megaregional Passenger Transportation Hub Location Problem Considering Congestion Effects

2021 ◽  
Vol 33 (4) ◽  
pp. 551-563
Author(s):  
Huang Yan ◽  
Xiaoning Zhang
Keyword(s):  
Location Problem ◽  
Travel Demand ◽  
Programming Model ◽  
Transportation Network ◽  
Network Capacity ◽  
Mixed Integer ◽  
Hub Location ◽  
Hub Location Problem ◽  
Passenger Transportation ◽  
Congestion Effects

The need to make effective plans for locating transportation hubs is of increasing importance in the megaregional area, as recent research suggests that the growing intercity travel demand affects the efficiency of a megaregional transportation system. This paper investigates a hierarchical facility location problem in a megaregional passenger transportation network. The aim of the study is to determine the locations of hub facilities at different hierarchical levels and distribute the demands to these facilities with minimum total cost, including investment, transportation, and congestion costs. The problem is formulated as a mixed-integer nonlinear programming model considering the service availability structure and hub congestion effects. A case study is designed to demonstrate the effectiveness of the proposed model in the Wuhan metropolitan area. The results show that the congestion effects can be addressed by reallocating the demand to balance the hub utilisation or constructing new hubs to increase the network capacity. The methods of appropriately locating hubs and distributing traffic flows are proposed to optimise the megaregional passenger transportation networks, which has important implications for decision makers.

Stability Analysis for a Force Augmenting Device Considering Delays in the Human Model

2013 ◽  
Author(s):  
Suresh K. Gadi ◽  
Ruben A. Garrido ◽  
Rogelio Lozano ◽  
Antonio Osorio
Keyword(s):  
Stability Analysis ◽  
Time Delay ◽  
Upper Bound ◽  
Time Delays ◽  
Human Operator ◽  
Human Model ◽  
Human Machine Interaction ◽  
Moving Force ◽  
Machine Interaction ◽  
Laboratory Prototype

This paper presents a stability analysis of the interaction between a human and a linear moving Force Augmenting Device (FAD). The analysis employs the mathematical models of the human, the FAD and their interaction. As a depart from past works, this article presents a stability analysis considering time-delays in the human model. A key ingredient in the analysis is the use of the Rekasius substitution for replacing the time-delay terms. It is proved that the human machine interaction is stable when the human model has no delays. The analysis provides an upper bound for the time-delays preserving a stable interaction. Numerical simulations allow to assess the human-FAD interaction. An experiment is performed with a laboratory prototype, where a human operator lifts a load. It is observed that the human machine interaction is stable and the human operator is able to move the load to its desired position by experiencing very little effort.

scholarly journals Grade Setting of a Timber Logistics Center Based on a Complex Network: A Case Study of 47 Timber Trading Markets in China

Information ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 107
Author(s):  
Liang Xue ◽  
Xin Huang ◽  
Yuchun Wu ◽  
Xingchen Yan ◽  
Yan Zheng
Keyword(s):  
Complex Network ◽  
Transportation Network ◽  
Long Distance ◽  
Logistics System ◽  
Logistics Center ◽  
Complex Network Theory ◽  
Network Characteristics ◽  
Transportation Capacity ◽  
Forested Areas ◽  
Set Up

The location and grade setting of a timber logistics center is an important link in the optimization of the timber logistics system, the rationality of which can effectively improve the efficiency of the timber logistics supply chain. There is a long distance between the main forested areas in China, and more than 55% of the timber demand depends on imports. Research and practice of systematically planning timber logistics centers in the whole country have not been well carried out, which reduces the efficiency of timber logistics. In this paper, 47 timber trading markets with a certain scale in China are selected as the basis for logistics center selection. Based on their transportation network relationship and the number of enterprises in the market, combined with the complex network theory and data analysis method, the network characteristics of three different transportation networks are measured. After determining the transportation capacity indicator, the logistics capacity coefficient is measured based on the freight volume of each node. Then, the important nodes are identified, and each node is graded to systematically set up the timber logistics center.

Definition and Evaluation Modeling of Transportation Network Layout Adaptability

2011 ◽  
Vol 71-78 ◽  
pp. 3938-3941 ◽  
Author(s):  
Jie Gao ◽  
Mei Xiang Wu ◽  
Chen Qiang Yin
Keyword(s):  
Heuristic Algorithm ◽  
Coefficient Of Variation ◽  
Large Scale ◽  
Transportation Networks ◽  
Transportation Network ◽  
Optimization Methods ◽  
Network Capacity ◽  
Network Layout ◽  
Proposed Model ◽  
Coordination Degree

According to the reliability theories and the characteristics of transportation networks, the layout adaptability is defined as the coupling and coordination degree of transportation network capacity and demand firstly. Then a layout adaptability model is built adopting the optimization methods, degree of layout adaptability index and coefficient of variation are used to evaluate the adaptability of scale and distribution respectively. Meanwhile, the heuristic algorithm suitable for large scale is designed to solve the proposed model. At last, a numerical example and its results are provided to demonstrate the validity of the proposed model and algorithm.

Risk assessment of UK electricity supply in a rapidly evolving energy sector

2008 ◽  
Vol 222 (7) ◽  
pp. 623-642 ◽  
Author(s):  
G P Hammond ◽  
R Waldron
Keyword(s):  
Risk Assessment ◽  
Network Capacity ◽  
Electricity Sector ◽  
Spare Capacity ◽  
Security Issues ◽  
Stakeholder Groups ◽  
Weather Events ◽  
Nuclear Plants ◽  
Assessment Techniques ◽  
The Uk

A range of major risks associated with a rapidly changing United Kingdom (UK) electricity sector have been identified and quantified with the aid of various stakeholder groups (academic researchers, civil servants, electricity companies, ‘green’ groups, power system engineers, and various others), who completed an online internet questionnaire. Each stakeholder ranked potential risks according to the perceived ‘severity of impact’ and ‘likelihood of occurrence’ using a three-point scale. The data were then used to perform a ranking of the risks by multiplying scores for impact and occurrence. There was some variation between the different stakeholder groups, but similar risks were ranked highly by each group. The main risks were identified as being energy security issues (the highest score), lack of investment in new infrastructure, the closure of old coal and nuclear plants leading to reduced network capacity, severe weather events, and inadequate spare capacity margins generally. The trial illustrates the potential of using risk assessment techniques to evaluate developing risks to the UK power landscape. Clearly such an exercise would need to be carried out periodically if it were to maintain its value to the industry, its stakeholders, and to policy makers.

scholarly journals Maritime Freight Data Collection Systems and Database to Support Performance Measures and Market Analyses

2020 ◽  
Author(s):  
P.S. Sriraj ◽  
◽  
Bo Zou ◽  
Lise Dirks ◽  
Nahid Parvez Farazi ◽  
...  
Keyword(s):  
Performance Measurement ◽  
Transportation Network ◽  
Network Capacity ◽  
The United States ◽  
The State ◽  
Army Corps ◽  
Army Corps Of Engineers ◽  
Inland Waterways ◽  
Us Army ◽  
The People

The Illinois Marine Transportation System (IMTS) is a key component of the nation’s inland waterway system. IMTS is comprised of 27 locks and dams, 19 port districts, more than 350 active terminals, and 1,118 miles of navigable inland waterways traversing along the borderline or within the state of Illinois. However, the infrastructure of IMTS is aging and its conditions are deteriorating. To monitor the performance of IMTS and guide infrastructure investment to enhance safety, efficiency, and reliability of the system, a comprehensive performance measurement program is needed. To this end, the objective of this project is to create an integrated, comprehensive, and maintainable database that facilitates performance measurement of maritime freight to, from, and through Illinois. To achieve this objective, a review of the literature on maritime freight transportation both in the United States and abroad was performed. To gauge practitioners’ points of view, a series of phone interviews and online surveys of Illinois’ neighboring state DOT officials, officials from the US Army Corps of Engineers, Illinois port district authorities, and carriers operating in Illinois was also conducted. With the findings from the literature review and an understanding of state DOT practices, the needed and available data sources for a maritime freight performance measurement program were identified. Building on all the above efforts, a first-of-its-kind PM database for IMTS was designed and developed, along with a detailed user manual, ready for IDOT’s immediate use and future updates. In addition, opportunities for IDOT to use the database to conduct analysis are discussed. Key programmatic recommendations that outline the role of IDOT as a champion and as a facilitator are further included. The outcome of this project will help IDOT gain much-needed knowledge of and develop programs to improve IMTS performance, increase multimodal transportation network capacity, and expand the transportation and logistics sector of the state, which ultimately benefit the people and economy of Illinois.

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