In recent years, indoor positioning has emerged as a critical function in many end-user applications; including military, civilian, disaster relief and peacekeeping missions. In comparison with outdoor environments, sensing location information in indoor environments requires a higher precision and is a more challenging task in part because various objects reflect and disperse signals. Ultra WideBand (UWB) is an emerging technology in the field of indoor positioning that has shown better performance compared to others. In order to set the stage for this work, we provide a survey of the state-of-the-art technologies in indoor positioning, followed by a detailed comparative analysis of UWB positioning technologies. We also provide an analysis of strengths, weaknesses, opportunities, and threats (SWOT) to analyze the present state of UWB positioning technologies. While SWOT is not a quantitative approach, it helps in assessing the real status and in revealing the potential of UWB positioning to effectively address the indoor positioning problem. Unlike previous studies, this paper presents new taxonomies, reviews some major recent advances, and argues for further exploration by the research community of this challenging problem space.

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Spam in Online Social Networks (OSNs) is a systemic problem that imposes a threat to these services in terms of undermining their value to advertisers and potential investors, as well as negatively affecting users' engagement. As spammers continuously keep creating newer accounts and evasive techniques upon being caught, a deeper understanding of their spamming strategies is vital to the design of future social media defense mechanisms. In this work, we present a unique analysis of spam accounts in OSNs viewed through the lens of their behavioral characteristics. Our analysis includes over 100 million messages collected from Twitter over the course of one month. We show that there exist two behaviorally distinct categories of spammers and that they employ different spamming strategies. Then, we illustrate how users in these two categories demonstrate different individual properties as well as social interaction patterns. Finally, we analyze the detectability of spam accounts with respect to three categories of features, namely, content attributes, social interactions, and profile properties.

Since early ages, people tried to predicate earthquakes using simple observations such as strange or atypical animal behavior. In this paper, we study data collected from past earthquakes to give better forecasting for coming earthquakes. We propose the application of artificial intelligent predication system based on artificial neural network which can be used to predicate the magnitude of future earthquakes in northern Red Sea area including the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez. We present performance evaluation for different configurations and neural network structures that show prediction accuracy compared to other methods. The proposed scheme is built based on feed forward neural network model with multi-hidden layers. The model consists of four phases: data acquisition, pre-processing, feature extraction and neural network training and testing. In this study the neural network model provides higher forecast accuracy than other proposed methods. Neural network model is at least 32% better than other methods. This is due to that neural network is capable to capture non-linear relationship than statistical methods and other proposed methods.

Protecting smartphones against security threats is a multidimensional problem involving human and technological factors. This study investigates how smartphone users’ security- and privacy-related decisions are influenced by their attitudes, perceptions, and understanding of various security threats. In this work, we seek to provide quantified insights into smartphone users’ behavior toward multiple key security features including locking mechanisms, application repositories, mobile instant messaging, and smartphone location services. To the best of our knowledge, this is the first study that reveals often unforeseen correlations and dependencies between various privacy- and security-related behaviors. Our work also provides evidence that making correct security decisions might not necessarily correlate with individuals’ awareness of the consequences of security threats. By comparing participants’ behavior and their motives for adopting or ignoring certain security practices, we suggest implementing additional persuasive approaches that focus on addressing social and technological aspects of the problem. On the basis of our findings and the results presented in the literature, we identify the factors that might influence smartphone users’ security behaviors. We then use our understanding of what might drive and influence significant behavioral changes to propose several platform design modifications that we believe could improve the security levels of smartphones.

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Fake identities and user accounts (also called "Sybils") in online communities represent today a treasure for adversaries to spread fake product reviews, malware and spam on social networks, and astroturf political campaigns. State-of-the-art in the defense mechanisms includes Automated Turing Tests (ATTs such as CAPTCHAs) and graph-based Sybil detectors. Sybil detectors in social networks leverage the assumption that Sybils will find it hard to befriend real users which leads to Sybils being connected to each other forming strongly connected sub graphs that can be detected using graph theory. However, the large majority of Sybils are in fact successful in integrating themselves into real user communities (such as the case in Twitter and Facebook). In this paper, we first study and compare the current detection mechanisms of Sybil accounts. We also explore various types of Twitter Sybil accounts detection features with the objective of building an effective and practical classifier. In order to build and evaluate our classifier, we collect and manually label a dataset of twitter accounts, including human users, bots, and hybrid (i.e., tweets are posted by both human and bots). We believe this Twitter Sybils corpus will help researchers in conducting sound measurement studies. We also develop a browser plug-in (that we call Twitter Sybils Detector or TSD for short) that utilizes our classifier and warns the user about possible Sybil accounts before accessing them, upon clicking on a Twitter account.

A great challenge in securing sensor networks is that sensor nodes can be physically compromised. Once a node is compromised, attackers can retrieve secret information (e.g. keys) from the node. In most of the key pre-distribution schemes, the compromise of secret information on one node can have substantial impact on other nodes because secrets are shared by more than one node in those schemes. Although tamper-resistant hardware can help protect those secrets, it is still impractical for sensor networks.Having observed that most sensor network applications and key pre-distribution schemes can tolerate the compromise of a small number of sensors, we propose to use diversity to protect the secret keys in sensor networks. Our scheme consists of two steps. First, we obfuscate the data and the code for each sensor, such that, when attackers have compromised a sensor node, they need to spend a substantial amount of time to find the secrets from the obfuscated code (e.g., by reverse engineering or code analysis). This first line of defense raises the bar of difficulty for a successful attack on one single node. Second, for different nodes, we make sure that the data and code obfuscation methods are different. This way, even if the attacks have successfully derived the location of the secrets, they cannot use the same location for another node, because for different nodes, their secrets are stored in different ways and in different places. Such diversity makes it a daunting job to derive the secret information from a large number of compromised nodes. We have implemented our scheme for Mica2 motes, and we present the results in this paper.