Robustness of controllability and recoverability of complex networks

Network robustness describes a network's ability to provide and maintain an acceptable level of service in the face of failures and challenges to normal operation. Unfortunately, failures of networks, such as power outages in power systems, congestions in transportation networks, failures of routers on the Internet, happen frequently in our...

Non-Consensus Opinion Model with Byzantine Nodes

pinion dynamics models study how the interaction among people influences the opinion formation process. In most opinion dynamics models, only one opinion can exist in the steady state, which is different from the real-life opinion formation process. In 2009, Shao et at. introduced a Non-Consensus Opinion (NCO) model, which allows different...

Spreading processes in complex networks and systems

Complex systems are made up of many interconnected components. The interactions between components further produce emerging complex collective behaviors. In most cases, a complex system can be represented as a network in which the nodes represent the elements and the connected links illustrate the interactions. The spreading process is one of...

Shallow Cumulus Clouds as Complex Networks

Clouds, specifically shallow clouds, are known as a major source of uncertainty in global climate models. Shallow clouds over the global oceans show different spatial patterns and organizations that may be influenced by climate change. Besides, the frequency of these patterns can change the climate feedback of marine clouds in the subtropics....

Epidemics on Networks: Analysis, Network Reconstruction and Prediction

The field of epidemiology encompasses a broad class of spreading phenomena, ranging from the seasonal influenza and the dissemination of fake news on online social media to the spread of neural activity over a synaptic network. The propagation of viruses, fake news and neural activity relies on the contact between individuals, social media...

Noiseless clusters and perturbations in networks of coupled quantum harmonic oscillators

In this thesis, networks of coupled quantum harmonic oscillators are studied. The dynamics of these networks are determined by single-frequency vibrations of the entire network called normal modes. We study the behavior of the nor- mal modes when the network is coupled to a thermodynamical heat bath by looking at the Lindblad Master Equation of...

Combining genetic regulatory network models and a random matrix approach to solve large biological networks

In this thesis we study genetic regulatory networks using a minimal nonlinear<br/>model from literature and extend this to multi-compartment gene-to-gene interaction networks using both numerical simulations and random matrix theory.<br/>When we add perturbations to a system of two interaction networks, the largest<br/>eigenvalue becomes larger,...

Performance of complex networks: Efficiency and Robustness

Network performance is determined by the interplay of underlying structures and overlying dynamic processes on networks. This thesis mainly considers two types of collective dynamics on networks, spread and transport, which are ubiquitous in our daily lives, ranging from information propagation, disease spreading, to molecular motors on...

Spreading on Networks

Spreading phenomena such as spreading of diseases, information and computer viruses are ubiquitous in nature and man-made systems, but the understanding of them is still insufficient. This dissertation focuses on the analysis of a basic mathematical model of spreading phenomena running on underlying network structures and aims to complete the...

On discrete and continuous state adaptive network models: with an application to self-organisation in swarming systems

We consider adaptive network models with discrete and continuous state sets obeying dynamical rules that enable application to swarming systems. The 2-state adaptive network contains a supercritical pitchfork bifurcation in the transition between ordered and disordered stationary solutions. We derive an adaptive network model that works on a...

Robustness of complex networks: Theory and application

Failures of networks, such as power outages in power systems, congestions in<br/>transportation networks, paralyse our daily life and introduce a tremendous cascading effect on our society. Networks should be constructed and operated in a robust way against random failures or deliberate attacks.<br/>We study how to add a single link into an...

Modular Structures, Robustness and Protection of Complex Networks: Theory, Complexity and Algorithms

Community structure is observed in many real-world networks, such as (online) social networks, where groups of friends of a certain person are often also friends of each other. Newman's modularity has been explored as an important quantitative metric for communities and clusters detection in networks. We present a new expressions and bounds for...