Papers by Lingfei "Teddy" Wu
Scientific Reports, 2015
Two classes of scaling behaviours, namely the super-linear scaling of links or activities, and th... more Two classes of scaling behaviours, namely the super-linear scaling of links or activities, and the sub-linear scaling of area, diversity, or time elapsed with respect to size have been found to prevail in the growth of complex networked systems. Despite some pioneering modelling approaches proposed for specific systems, whether there exists some general mechanisms that account for the origins of such scaling behaviours in different contexts, especially in socioeconomic systems, remains an open question. We address this problem by introducing a geometric network model without free parameter, finding that both super-linear and sub-linear scaling behaviours can be simultaneously reproduced and that the scaling exponents are exclusively determined by the dimension of the Euclidean space in which the network is embedded. We implement some realistic extensions to the basic model to offer more accurate predictions for cities of various scaling behaviours and the Zipf distribution reported in the literature and observed in our empirical studies. All of the empirical results can be precisely recovered by our model with analytical predictions of all major properties. By virtue of these general findings concerning scaling behaviour, our models with simple mechanisms gain new insights into the evolution and development of complex networked systems.
PloS one, 2014
We view web forums as virtual living organisms feeding on user's clicks and investigate how t... more We view web forums as virtual living organisms feeding on user's clicks and investigate how they grow at the expense of clickstreams. We find that PV(t) (the number of page views in a given time period) and UV(t) (the number of unique visitors in the time period) of the studied forums satisfy the law of the allometric growth, i.e., PV(t) ~ UV(t)((θ). We construct clickstream networks and explain the observed temporal dynamics of networks by the interactions between nodes. We describe the transportation of clickstreams using the function D(i) ~ T(i)(γ), in which T(i) is the total amount of clickstreams passing through node i and D(i) is the amount of the clickstreams dissipated from i to the environment. It turns out that γ, an indicator for the efficiency of network dissipation, not only negatively correlates with θ, but also sets the bounds for θ. In particular, 1/γ > θ when 0 < γ < 1 and 1/γ < θ when γ > 1. Our findings have practical consequences. For example, ...
Revealed Preference in Networks
Index Numbers and Information Networks
ABSTRACT
Modeling population dynamics of online communities
Research on the growth of online tagging systems not only is interesting in its own right, but al... more Research on the growth of online tagging systems not only is interesting in its own right, but also yields insights for website management and semantic web analysis. Traditional models that describing the growth of online systems can be divided between linear and nonlinear versions. Linear models, including the BA model [A.L. Barabasi, R. Albert, Science 286, 509 (1999)], assume that the average activity of users is a constant independent of population. Hence the total activity is a linear function of population. On the contrary, nonlinear models suggest that the average activity is affected by the size of the population and the total activity is a nonlinear function of population. In the current study, supporting evidences for the nonlinear growth assumption are obtained from data on Internet users' tagging behavior. A power law relationship between the number of new tags (F ) and the population (P ), which can be expressed as F ∼ P γ (γ > 1), is found. I call this pattern accelerating growth and find it relates the to time-invariant heterogeneity in individual activities. I also show how a greater heterogeneity leads to a faster growth.
The decentralized flow structure of clickstreams on the web
ABSTRACT
The core of the Web is a hyperlink navigation system collaboratively set up by webmasters to help... more The core of the Web is a hyperlink navigation system collaboratively set up by webmasters to help users find desired websites. But does this system really work as expected?
PLoS ONE, 2013
Background: An ecological flow network is a weighted directed graph in which the nodes are specie... more Background: An ecological flow network is a weighted directed graph in which the nodes are species, the edges are ''who eats whom'' relationships and the weights are rates of energy or nutrient transferred between species. Allometric scaling is a ubiquitous feature for flow systems such as river basins, vascular networks and food webs.
Physical Review E, 2011
Research on human activities online usually assumes the linear relationship between active popula... more Research on human activities online usually assumes the linear relationship between active population P and total activity T , that is, T ∼ P γ (γ = 1). However, in our research, we find that the power law relationship T ∼ P γ (γ > 1), also called accelerating growth, turns out to be ubiquitous in online activities such as micro-blogging, voting and tagging. Moreover, in the online activities under study, a unique type of distribution that changes with system size emerges. We name it sizedependent distribution and find it may give rise to accelerating growth. Interestingly, the power law exponent of accelerating growth γ is determined by the size-dependent exponent but not the Zipf or power law exponent of distributions. This is contradict to our intuition and previous studies. PACS numbers: 89.75.-k,89.75.Da
Online shopping among Chinese consumers: an exploratory investigation of demographics and value orientation
International Journal of Consumer Studies, 2011
Page 1. Online shopping among Chinese consumers: an exploratory investigation of demographics and... more Page 1. Online shopping among Chinese consumers: an exploratory investigation of demographics and value orientationijcs_982 1..12 Lingfei Wu,1 Yi Cai2 and Dehuan Liu1 1College of Media and Communication, Peking ...
Chinese Citizen's Attitude towards Internet Censorship: a Survey in Mainland China, 2005
The aim of this study is to describe Chinese citizen's attitude towards Internet censorship,... more The aim of this study is to describe Chinese citizen's attitude towards Internet censorship, and explore variables that affect it. A dataset that contains 1,620 cases was used. It was found that the interviewee's Internet usage experience had an influence on ...
Allometric growth is found in many tagging systems online. That is, the number of new tags (T ) i... more Allometric growth is found in many tagging systems online. That is, the number of new tags (T ) is a power law function of the active population (P ), or T ∼ P γ (γ = 1). According to previous studies, it is the heterogeneity in individual tagging behavior that gives rise to allometric growth. These studies consider the power-law distribution model with an exponent β, regarding 1/β as an index for heterogeneity. However, they did not discuss whether power-law is the only distribution that leads to allometric growth, or equivalently, whether the positive correlation between heterogeneity and allometric growth holds in systems of distributions other than power-law. In this paper, the authors systematically examine the growth pattern of systems of six different distributions, and find that both power-law distribution and log-normal distribution lead to allometric growth. Furthermore, by introducing Shannon entropy as an indicator for heterogeneity instead of 1/β, the authors confirm that the positive relationship between heterogeneity and allometric growth exists in both cases of power-law and log-normal distributions.
Magnetic fusion could provide an inexhaustible, clean, and safe solution to the global energy nee... more Magnetic fusion could provide an inexhaustible, clean, and safe solution to the global energy needs. The success of magnetically-confined fusion reactors demands steady-state plasma confinement which is challenged by the edge turbulence such as the blob-filaments. Real-time analysis can be used to monitor the progress of fusion experiments and prevent catastrophic events. We present a real-time outlier detection algorithm to efficiently find blobs in fusion experiments and numerical simulations. We have implemented this algorithm with hybrid MPI/OpenMP and demonstrated the accuracy and efficiency with a set of data from the XGC1 fusion simulation code. Our tests show that we can complete blob detection in two or three milliseconds using Edison, a Cray XC30 system at NERSC and achieve linear time speedup. We plan to apply the detection algorithm to experimental measurement data from operating fusion devices. We also plan to develop a blob tracking algorithm based on the proposed method.
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Papers by Lingfei "Teddy" Wu