348 research outputs found
On the Feasibility of Social Network-based Pollution Sensing in ITSs
Intense vehicular traffic is recognized as a global societal problem, with a
multifaceted influence on the quality of life of a person. Intelligent
Transportation Systems (ITS) can play an important role in combating such
problem, decreasing pollution levels and, consequently, their negative effects.
One of the goals of ITSs, in fact, is that of controlling traffic flows,
measuring traffic states, providing vehicles with routes that globally pursue
low pollution conditions. How such systems measure and enforce given traffic
states has been at the center of multiple research efforts in the past few
years. Although many different solutions have been proposed, very limited
effort has been devoted to exploring the potential of social network analysis
in such context. Social networks, in general, provide direct feedback from
people and, as such, potentially very valuable information. A post that tells,
for example, how a person feels about pollution at a given time in a given
location, could be put to good use by an environment aware ITS aiming at
minimizing contaminant emissions in residential areas. This work verifies the
feasibility of using pollution related social network feeds into ITS
operations. In particular, it concentrates on understanding how reliable such
information is, producing an analysis that confronts over 1,500,000 posts and
pollution data obtained from on-the- field sensors over a one-year span.Comment: 10 pages, 15 figures, Transaction Forma
Guiding internet-scale video service deployment using microblog-based prediction
Mini-Conference - MC16: Social NetworksOnline microblogging has been very popular in today's Internet, where users exchange short messages and follow various contents shared by people that they are interested in. Among the variety of exchanges, video links are a representative type on a microblogging site. More and more viewers of an Internet video service are coming from microblog recommendations. It is intriguing research to explore the connections between the patterns of microblog exchanges and the popularity of videos, in order to potentially use the propagation patterns of microblogs to guide proactive service deployment of a video sharing system. Based on extensive traces from Youku and Tencent Weibo, a popular video sharing site and a favored microblogging system in China, we explore how patterns of video link propagation in the microblogging system are correlated with video popularity on the video sharing site, at different times and in different geographic regions. Using influential factors summarized from the measurement studies, we further design neural network-based learning frameworks to predict the number of potential viewers of different videos and the geographic distribution of viewers. Experiments show that our neural network-based frameworks achieve better prediction accuracy, as compared to a classical approach that relies on historical numbers of views. We also briefly discuss how proactive video service deployment can be effectively enabled by our prediction frameworks. © 2012 IEEE.published_or_final_versionThe 31st Annual IEEE International Conference on Computer Communications (IEEE INFOCOM 2012), Orlando, FL., 25-30 March 2012. In IEEE Infocom Proceedings, 2012, p. 2901-290
Fame for sale: efficient detection of fake Twitter followers
are those Twitter accounts specifically created to
inflate the number of followers of a target account. Fake followers are
dangerous for the social platform and beyond, since they may alter concepts
like popularity and influence in the Twittersphere - hence impacting on
economy, politics, and society. In this paper, we contribute along different
dimensions. First, we review some of the most relevant existing features and
rules (proposed by Academia and Media) for anomalous Twitter accounts
detection. Second, we create a baseline dataset of verified human and fake
follower accounts. Such baseline dataset is publicly available to the
scientific community. Then, we exploit the baseline dataset to train a set of
machine-learning classifiers built over the reviewed rules and features. Our
results show that most of the rules proposed by Media provide unsatisfactory
performance in revealing fake followers, while features proposed in the past by
Academia for spam detection provide good results. Building on the most
promising features, we revise the classifiers both in terms of reduction of
overfitting and cost for gathering the data needed to compute the features. The
final result is a novel classifier, general enough to thwart
overfitting, lightweight thanks to the usage of the less costly features, and
still able to correctly classify more than 95% of the accounts of the original
training set. We ultimately perform an information fusion-based sensitivity
analysis, to assess the global sensitivity of each of the features employed by
the classifier. The findings reported in this paper, other than being supported
by a thorough experimental methodology and interesting on their own, also pave
the way for further investigation on the novel issue of fake Twitter followers
Graph-based security and privacy analytics via collective classification
Graphs are a powerful tool to represent complex interactions between various entities. A particular family of graph-based machine learning techniques called collective classification has been applied to various security and privacy problems, e.g., malware detection, Sybil detection in social networks, fake review detection, malicious website detection, auction fraud detection, APT infection detection, attribute inference attacks, etc.. Moreover, some collective classification methods have been deployed in industry, e.g., Symantec deployed collective classification to detect malware; Tuenti, the largest social network in Spain, deployed collective classification to detect Sybils.
In this dissertation, we aim to systematically study graph-based security and privacy problems that are modeled via collective classification. In particular, we focus on collective classification methods that leverage random walk (RW) or loopy belief propagation (LBP).
First, we propose a local rule-based framework to unify existing RW-based and LBP-based methods. Under our framework, existing methods can be viewed as iteratively applying a different local rule to every node in the graph. know about the node.
Second, we design a novel local rule for undirected graphs. Based on our local rule, we propose a collective classification method that can maintain the advantages and overcome the disadvantages of state-of-the-art undirected graph-based collective classification methods for Sybil detection.
Third, many security and privacy problems are modeled using directed graphs. Directed graph- based security and privacy problems have their unique characteristics. Existing undirected graph- based collective classification methods (e.g., LBP-based methods) cannot be applied to directed graphs and existing directed graph-based methods (e.g., RW-based methods) cannot make full use of the labeled training set. To address the issue, we develop a novel local rule for directed graph-based Sybil detection and propose a collective classification method that captures unique characteristics of directed graph-based Sybil detection.
Finally, one key issue of all collective classification methods is that they either assign small weights to a large number of edges whose two corresponding nodes have the same label or/and assign large weights to a large number of edges whose two corresponding nodes have different labels. Although collective classification has been studied and applied for security and privacy problems for more than a decade, it is still challenging to assign edge weights such that an edge has a large weight if the two corresponding nodes have the same label, and a small weight otherwise. We develop a novel collective classification framework to address this long-standing challenge. Specifically, we first formulate learning edge weights as an optimization problem, which, however, is computationally challenging to solve. Then, we relax the optimization problem and design an efficient joint weight learning and propagation algorithm to solve this approximate optimization problem
Affecting public opinions via social media--opinion leaders use of Weibo
This thesis analyzed opinion leaders' use of Weibo to investigate their online behaviors, and to see if gender and fields of expertise will affect opinion leaders' use of Weibo. The study will help people to better understand how opinion leaders in China use Weibo for their daily information consumption and communication, and will give us suggestive answers to the question of how to use Weibo to spread information effectively. Through online observation and content analysis, this study categorized the general online behavior patterns of opinion leaders' use of Weibo, and found that gender is positively correlated to the externality of the tweets and the aggressiveness of the tweets, while fields of expertise is negatively correlated to tweets' popularity. The study contributes to the current literatures by bringing new understanding to agenda setting theory, the concept of gatekeeping and agenda melding in the digital age, and the findings may help us better understand how opinion leaders in China consume and communicate information on Weibo, from both qualitative and quantitative perspectives, and shed light on the influence of opinion leaders' gender and fields of expertise on their communication behavior on Weibo
ANALYZING IMAGE TWEETS IN MICROBLOGS
Ph.DDOCTOR OF PHILOSOPH
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