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Articles 4321 - 4350 of 6867

Full-Text Articles in Physical Sciences and Mathematics

An Air Index For Spatial Query Processing In Road Networks, Weiwei Sun, Chunan Chen, Baihua Zheng, Chong Chen, Peng Liu Jun 2014

An Air Index For Spatial Query Processing In Road Networks, Weiwei Sun, Chunan Chen, Baihua Zheng, Chong Chen, Peng Liu

Research Collection School Of Computing and Information Systems

Spatial queries such as range query and kNN query in road networks have received a growing number of attention in real life. Considering the large population of the users and the high overhead of network distance computation, it is extremely important to guarantee the efficiency and scalability of query processing. Motivated by the scalable and secure properties of wireless broadcast model, this paper presents an air index called Network Partition Index (NPI) to support efficient spatial query processing in road networks via wireless broadcast. The main idea is to partition the road network into a number of regions and then …

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Recommendation Support For Multi-Attribute Databases, Jilian Zhang Jun 2014

Recommendation Support For Multi-Attribute Databases, Jilian Zhang

Dissertations and Theses Collection (Open Access)

This dissertation studies the subject of providing recommendation support for multi-attribute databases. Recommendation is an important and very useful information evaluation mechanism that explores a database of huge volume, and retrieves from it the interesting data items (tuples) for users based on their preferences.

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Ranking-Based Approaches For Localizing Faults, Lucia Lucia Jun 2014

Ranking-Based Approaches For Localizing Faults, Lucia Lucia

Dissertations and Theses Collection (Open Access)

A fault is the root cause of program failures where a program behaves differently from the intended behavior. Finding or localizing faults is often laborious (especially so for complex programs), yet it is an important task in the software lifecycle. An automated technique that can accurately and quickly identify the faulty code is greatly needed to alleviate the costs of software debugging. Many fault localization techniques assume that faults are localizable, i.e., each fault manifests only in a single or a few lines of code that are close to one another. To verify this assumption, we study how faults spread …

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Air Indexing For On-Demand Xml Data Broadcast, Weiwei Sun, Rongrui Qin, Jinjin Wu, Baihua Zheng Jun 2014

Air Indexing For On-Demand Xml Data Broadcast, Weiwei Sun, Rongrui Qin, Jinjin Wu, Baihua Zheng

Research Collection School Of Computing and Information Systems

XML data broadcast is an efficient way to disseminate semi-structured information in wireless mobile environments. In this paper, we propose a novel two-tier index structure to facilitate the access of XML document in an on-demand broadcast system. It provides the clients with an overall image of all the XML documents available at the server side and hence enables the clients to locate complete result sets accordingly. A pruning strategy is developed to cut down the index size and a two-tier structure is proposed to further remove any redundant information. In addition, two index distribution strategies, namely naive distribution and partial …

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Evolving An Information Systems Capstone Course To Align With The Fast Changing Singapore Marketplace, Chris Boesch, Benjamin Kok Siew Gan Jun 2014

Evolving An Information Systems Capstone Course To Align With The Fast Changing Singapore Marketplace, Chris Boesch, Benjamin Kok Siew Gan

Research Collection School Of Computing and Information Systems

Every year, around fifty-five undergraduate teams of four to six students are required to complete a capstone course for the School of Information Systems at Singapore Management University. Each team spends approximately five months working with an industry sponsor using the latest tools and techniques. Students actively learn by implementing the system to solve a real world problem. In addition to delivering value to the local sponsor, our students learn specialized skills currently needed in the marketplace, which might not yet be incorporated into electives and core courses. In this paper, we discuss the tradeoffs of providing students and project …

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Cross-Language Bug Localization, Xin Xia, David Lo, Xingen Wang, Chenyi Zhang, Xinyu Wang Jun 2014

Cross-Language Bug Localization, Xin Xia, David Lo, Xingen Wang, Chenyi Zhang, Xinyu Wang

Research Collection School Of Computing and Information Systems

Bug localization refers to the process of identifying source code files that contain defects from textual descriptions in bug reports. Existing bug localization techniques work on the assumption that bug reports, and identifiers and comments in source code files, are written in the same language (i.e., English). However, software users from non-English speaking countries (e.g., China) often use their native languages (e.g., Chinese) to write bug reports. For this setting, existing studies on bug localization would not work as the terms that appear in the bug reports do not appear in the source code. We refer to this problem as …

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Revisiting Risk-Sensitive Mdps: New Algorithms And Results, Ping Hou, William Yeoh, Pradeep Reddy Varakantham Jun 2014

Revisiting Risk-Sensitive Mdps: New Algorithms And Results, Ping Hou, William Yeoh, Pradeep Reddy Varakantham

Research Collection School Of Computing and Information Systems

While Markov Decision Processes (MDPs) have been shown to be effective models for planning under uncertainty, theobjective to minimize the expected cumulative cost is inappropriate for high-stake planning problems. As such, Yu, Lin, and Yan (1998) introduced the Risk-Sensitive MDP (RSMDP) model, where the objective is to find a policy that maximizes the probability that the cumulative cost is within some user-defined cost threshold. In this paper, we revisit this problem and introduce new algorithms that are based on classical techniques, such as depth-first search and dynamic programming, and a recently introduced technique called Topological Value Iteration (TVI). We demonstrate …

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Online Community Transition Detection, Biying Tan, Feida Zhu, Qiang Qu, Siyuan Liu Jun 2014

Online Community Transition Detection, Biying Tan, Feida Zhu, Qiang Qu, Siyuan Liu

Research Collection School Of Computing and Information Systems

Mining user behavior patterns in social networks is of great importance in user behavior analysis, targeted marketing, churn prediction and other applications. However, less effort has been made to study the evolution of user behavior in social communities. In particular, users join and leave communities over time. How to automatically detect the online community transitions of individual users is a research problem of immense practical value yet with great technical challenges. In this paper, we propose an algorithm based on the Minimum Description Length (MDL) principle to trace the evolution of community transition of individual users, adaptive to the noisy …

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Paths Of Influence For Innovations In Financial Is And Technology Ecosystems, Jun Liu, Robert John Kauffman, Dan Ma Jun 2014

Paths Of Influence For Innovations In Financial Is And Technology Ecosystems, Jun Liu, Robert John Kauffman, Dan Ma

Research Collection School Of Computing and Information Systems

Predicting technological innovations in financial information systems (IS) and technology ecosystems has been challenging for technology forecasters and industry analysts due to their underlying complexity. Technology-based financial innovations over the past four decades, such as programmed trading in the 1980s, risk-adjusted return on capital-based financial risk management systems in the 1990s, high-frequency trading and Internet banking in 2000s, and now mobile payments in the 2010s, have all led to transformations in the financial services industry. What basis can be identified to predict such new innovations? And what areas of financial services will they affect? This study applies the technology ecosystem …

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Fully Secure Key-Policy Attribute-Based Encryption With Constant-Size Ciphertexts And Fast Decryption, Junzuo Lai, Robert H. Deng, Yingjiu Li, Jian Weng Jun 2014

Fully Secure Key-Policy Attribute-Based Encryption With Constant-Size Ciphertexts And Fast Decryption, Junzuo Lai, Robert H. Deng, Yingjiu Li, Jian Weng

Research Collection School Of Computing and Information Systems

Attribute-based encryption (ABE), introduced by Sahai and Waters, is a promising cryptographic primitive, which has been widely applied to implement fine-grained access control system for encrypted data. In its key-policy flavor, attribute sets are used to annotate ciphertexts and secret keys are associated with access structures that specify which ciphertexts a user is entitled to decrypt. In most existing key-policy attribute-based encryption (KP-ABE) constructions, the size of the ciphertext is proportional to the number of attributes associated with it and the decryption cost is proportional to the number of attributes used during decryption. In this paper, we present a new …

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Scc-Based Improved Reachability Analysis For Markov Decision Processes, Lin Gui, Jun Sun, Songzheng Song, Yang Liu, Jin Song Dong May 2014

Scc-Based Improved Reachability Analysis For Markov Decision Processes, Lin Gui, Jun Sun, Songzheng Song, Yang Liu, Jin Song Dong

Research Collection School Of Computing and Information Systems

Markov decision processes (MDPs) are extensively used to model systems with both probabilistic and nondeterministic behavior. The problem of calculating the probability of reaching certain system states (hereafter reachability analysis) is central to the MDP-based system analysis. It is known that existing approaches on reachability analysis for MDPs are often inefficient when a given MDP contains a large number of states and loops, especially with the existence of multiple probability distributions. In this work, we propose a method to eliminate strongly connected components (SCCs) in an MDP using a divide-and-conquer algorithm, and actively remove redundant probability distributions in the MDP …

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Practical Analysis Framework For Software-Based Attestation Scheme, Li Li, Hong Hu, Jun Sun, Yang Liu, Dong Jin Song May 2014

Practical Analysis Framework For Software-Based Attestation Scheme, Li Li, Hong Hu, Jun Sun, Yang Liu, Dong Jin Song

Research Collection School Of Computing and Information Systems

An increasing number of ”smart” embedded devices are employed in our living environment nowadays. Unlike traditional computer systems, these devices are often physically accessible to the attackers. It is therefore almost impossible to guarantee that they are un-compromised, i.e., that indeed the devices are executing the intended software. In such a context, software-based attestation is deemed as a promising solution to validate their software integrity. It guarantees that the software running on the embedded devices are un-compromised without any hardware support. However, designing software-based attestation protocols are shown to be error-prone. In this work, we develop a framework for design …

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Tauth: Verifying Timed Security Protocols, Li Li, Jun Sun, Yang Liu, Jin Song Dong May 2014

Tauth: Verifying Timed Security Protocols, Li Li, Jun Sun, Yang Liu, Jin Song Dong

Research Collection School Of Computing and Information Systems

Quantitative timing is often relevant to the security of systems, like web applications, cyber-physical systems, etc. Verifying timed security protocols is however challenging as both arbitrary attacking behaviors and quantitative timing may lead to undecidability. In this work, we develop a service framework to support intuitive modeling of the timed protocol, as well as automatic verification with an unbounded number of sessions. The partial soundness and completeness of our verification algorithms are formally defined and proved. We implement our method into a tool called TAuth and the experiment results show that our approach is efficient and effective in both finding …

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A Hybrid Model Of Connectors In Cyber-Physical Systems, Xiaohong Chen, Jun Sun, Meng Sun Sun May 2014

A Hybrid Model Of Connectors In Cyber-Physical Systems, Xiaohong Chen, Jun Sun, Meng Sun Sun

Research Collection School Of Computing and Information Systems

Compositional coordination models and languages play an important role in cyber-physical systems (CPSs). In this paper, we introduce a formal model for describing hybrid behaviors of connectors in CPSs. We extend the constraint automata model, which is used as the semantic model for the exogenous channel-based coordination language Reo, to capture the dynamic behavior of connectors in CPSs where the discrete and continuous dynamics co-exist and interact with each other. In addition to the formalism, we also provide a theoretical compositional approach for constructing the product automata for a Reo circuit, which is typically obtained by composing several primitive connectors …

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Gpu Accelerated Counterexample Generation In Ltl Model Checking, Zhimin Wu, Yang Liu, Yun Liang, Jun Sun May 2014

Gpu Accelerated Counterexample Generation In Ltl Model Checking, Zhimin Wu, Yang Liu, Yun Liang, Jun Sun

Research Collection School Of Computing and Information Systems

Strongly Connected Component (SCC) based searching is one of the most popular LTL model checking algorithms. When the SCCs are huge, the counterexample generation process can be time-consuming, especially when dealing with fairness assumptions. In this work, we propose a GPU accelerated counterexample generation algorithm, which improves the performance by parallelizing the Breadth First Search (BFS) used in the counterexample generation. BFS work is irregular, which means it is hard to allocate resources and may suffer from imbalanced load. We make use of the features of latest CUDA Compute Architecture-NVIDIA Kepler GK110 to achieve the dynamic parallelism and memory hierarchy …

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Learning Directional Co-Occurrence For Human Action Classification, Hong Liu, Mengyuan Liu, Qianru Sun May 2014

Learning Directional Co-Occurrence For Human Action Classification, Hong Liu, Mengyuan Liu, Qianru Sun

Research Collection School Of Computing and Information Systems

Spatio-temporal interest point (STIP) based methods have shown promising results for human action classification. However, state-of-art works typically utilize bag-of-visual words (BoVW), which focuses on the statistical distribution of features but ignores their inherent structural relationships. To solve this problem, a descriptor, namely directional pair-wise feature (DPF), is proposed to encode the mutual direction information between pairwise words, aiming at adding more spatial discriminant to BoVW. Firstly, STIP features are extracted and classified into a set of labeled words. Then in each frame, the DPF is constructed for every pair of words with different labels, according to their assigned directional …

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Lifi: Line-Of-Sight Identification With Wifi, Zimu Zhou, Zheng Yang, Chenshu Wu, Wei Sun, Yunhao Liu May 2014

Lifi: Line-Of-Sight Identification With Wifi, Zimu Zhou, Zheng Yang, Chenshu Wu, Wei Sun, Yunhao Liu

Research Collection School Of Computing and Information Systems

Wireless LANs, especially WiFi, have been pervasively deployed and have fostered myriad wireless communication services and ubiquitous computing applications. A primary concern in designing each scenario-tailored application is to combat harsh indoor propagation environments, particularly Non-LineOf-Sight (NLOS) propagation. The ability to distinguish LineOf-Sight (LOS) path from NLOS paths acts as a key enabler for adaptive communication, cognitive radios, robust localization, etc. Enabling such capability on commodity WiFi infrastructure, however, is prohibitive due to the coarse multipath resolution with mere MAC layer RSSI. In this work, we dive into the PHY layer and strive to eliminate irrelevant noise and NLOS paths …

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The Case For Open Source Software, Singapore Management University May 2014

The Case For Open Source Software, Singapore Management University

Perspectives@SMU

You use it more often than you are aware, and you can even use it to get a job

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Supporting Non-Verbal Visual Communication In Online Group Art Therapy, Brennan Jones, Kate Collie, Sara Prins Hankinson, Anthony Tang May 2014

Supporting Non-Verbal Visual Communication In Online Group Art Therapy, Brennan Jones, Kate Collie, Sara Prins Hankinson, Anthony Tang

Research Collection School Of Computing and Information Systems

Art therapy provides therapeutic benefit to people suffering from chronic pain, and recent work has explored supporting art therapy through online tools such as chat forums and discussion boards. These tools give people the benefit of engaging in art therapy without the burden of having to leave one’s home (when transportation may be a challenge), and allowing people to reveal their identities through dialogue and activity rather than through one’s appearance. However, these tools also do not provide much opportunity for collaboration and shared art making. Because group members are not aware of each other’s actions and non-verbal cues in …

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Detecting Anomaly Collections Using Extreme Feature Ranks, Hanbo Dai, Feida Zhu, Ee Peng Lim, Hwee Hwa Pang May 2014

Detecting Anomaly Collections Using Extreme Feature Ranks, Hanbo Dai, Feida Zhu, Ee Peng Lim, Hwee Hwa Pang

Research Collection School Of Computing and Information Systems

Detecting anomaly collections is an important task with many applications, including spam and fraud detection. In an anomaly collection, entities often operate in collusion and hold different agendas to normal entities. As a result, they usually manifest collective extreme traits, i.e., members of an anomaly collection are consistently clustered toward the top or bottom ranks on certain features. We therefore propose to detect these anomaly collections by extreme feature ranks. We introduce a novel anomaly definition called Extreme Rank Anomalous Collection or ERAC. We propose a new measure of anomalousness capturing collective extreme traits based on a statistical model. As …

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Technique For Authenticating H.264/Svc And Its Performance Evaluation Over Wireless Mobile Networks, Yifan Zhao, Swee Won Lo, Robert H. Deng, Xuhua Ding May 2014

Technique For Authenticating H.264/Svc And Its Performance Evaluation Over Wireless Mobile Networks, Yifan Zhao, Swee Won Lo, Robert H. Deng, Xuhua Ding

Research Collection School Of Computing and Information Systems

In this paper, a bit stream-based authentication scheme for H.264/Scalable Video Coding (SVC) is proposed. The proposed scheme seamlessly integrates cryptographic algorithms and Erasure Correction Codes (ECCs) to SVC video streams such that the authenti- cated streams are format compliant with the SVC specifications and preserve the three- dimensional scalability (i.e., spatial, quality and temporal) of the original streams. We implement our scheme on a smart phone and study its performance over a realistic bursty packet-lossy wireless mobile network. Our analysis and experimental results show that the scheme achieves very high verification rates with lower communication overhead and much smaller …

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Decentralized Multi-Agent Reinforcement Learning In Average-Reward Dynamic Dcops, Duc Thien Nguyen, William Yeoh, Hoong Chuin Lau, Shlomo Zilberstein May 2014

Decentralized Multi-Agent Reinforcement Learning In Average-Reward Dynamic Dcops, Duc Thien Nguyen, William Yeoh, Hoong Chuin Lau, Shlomo Zilberstein

Research Collection School Of Computing and Information Systems

Researchers have introduced the Dynamic Distributed Constraint Optimization Problem (Dynamic DCOP) formulation to model dynamically changing multi-agent coordination problems, where a dynamic DCOP is a sequence of (static canonical) DCOPs, each partially different from the DCOP preceding it. Existing work typically assumes that the problem in each time step is decoupled from the problems in other time steps, which might not hold in some applications. Therefore, in this paper, we make the following contributions: (i) We introduce a new model, called Markovian Dynamic DCOPs (MD-DCOPs), where the DCOP in the next time step is a function of the value assignments …

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Physio@Home: Design Explorations To Support Movement Guidance, Richard Tang, Hesam Alizadeh, Anthony Tang, Scott Bateman, Joaquim A.P. Jorge May 2014

Physio@Home: Design Explorations To Support Movement Guidance, Richard Tang, Hesam Alizadeh, Anthony Tang, Scott Bateman, Joaquim A.P. Jorge

Research Collection School Of Computing and Information Systems

Patients typically undergo physiotherapy with the help of a physiotherapist who teaches, guides, and corrects the patients as they perform exercises. It would be nice if people could repeat these exercises at home, potentially improving their recovery rate. However, without guidance and/or corrective feedback from a physiotherapist, the patient will not know whether they are doing their exercises correctly. To address this problem, we implemented a prototype that guides patients through pre-recorded exercise movements using visual guides overlaid atop a mirror-view of the patient on a wall-mounted display. We conducted informal evaluations and pilot studies to assess our prototype and …

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Exploring Video Streaming In Public Settings: Shared Geocaching Over Distance Using Mobile Video Chat, Jason Procyk, Carman Neustaedter, Carolyn Pang, Anthony Tang, Tejinder K. Judge May 2014

Exploring Video Streaming In Public Settings: Shared Geocaching Over Distance Using Mobile Video Chat, Jason Procyk, Carman Neustaedter, Carolyn Pang, Anthony Tang, Tejinder K. Judge

Research Collection School Of Computing and Information Systems

Our research explores the use of mobile video chat in public spaces by people participating in parallel experiences, where both a local and remote person are doing the same activity together at the same time. We prototyped a wearable video chat experience and had pairs of friends and family members participate in 'shared geocaching' over distance. Our results show that video streaming works best for navigation tasks but is more challenging to use for fine-grained searching tasks. Video streaming also creates a very intimate experience with a remote partner, but this can lead to distraction from the 'real world' and …

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On Coordinating Pervasive Persuasive Agents, Budhitama Subagdja, Ah-Hwee Tan May 2014

On Coordinating Pervasive Persuasive Agents, Budhitama Subagdja, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

There is a growing interest in applying multiagent systems for smart-home environment supporting self-caring elderly. In this paper we investigate situations and conditions for coordination for such kind of system. We specify a high level architecture of it based on the notions of beliefs, desires, and intentions for both individual and group behavior of the agents including the human occupant's. The framework enables flexible coordinations among loosely-coupled heterogeneous agents that converse with the user. This work is conducted towards producing a coordination framework for agents and people in such a kind of smart-home environment as mentioned.

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Declarative-Procedural Memory Interaction In Learning Agents, Wenwen Wang, Ah-Hwee Tan, Loo-Nin Teow, Tan Yuan-Sin May 2014

Declarative-Procedural Memory Interaction In Learning Agents, Wenwen Wang, Ah-Hwee Tan, Loo-Nin Teow, Tan Yuan-Sin

Research Collection School Of Computing and Information Systems

It has been well recognized that human makes use of both declarative memory and procedural memory for decision making and problem solving. In this paper, we propose a computational model with the overall architecture and individual processes for realizing the interaction between the declarative and procedural memory based on self-organizing neural networks. We formalize two major types of memory interactions and show how each of them can be embedded into autonomous reinforcement learning agents. Our experiments based on the Toad and Frog puzzle and a strategic game known as Starcraft Broodwar have shown that the cooperative interaction between declarative knowledge …

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Medical Imaging Specialists And 3d: A Domain Perspective On Mobile 3d Interactions, Teddy Seyed, Frank Maurer, Francisco Marinho Rodrigues, Anthony Tang May 2014

Medical Imaging Specialists And 3d: A Domain Perspective On Mobile 3d Interactions, Teddy Seyed, Frank Maurer, Francisco Marinho Rodrigues, Anthony Tang

Research Collection School Of Computing and Information Systems

3D volumetric medical images, such as MRIs, are commonly explored and interacted with by medical imaging experts using systems that require keyboard and mouse-based techniques. These techniques have presented challenges for medical imaging specialists: 3D spatial navigation is difficult, in addition to the detailed selection and analysis of 3D medical images being difficult due to depth perception and occlusion issues. In this work, we explore a potential solution to these challenges by using tangible interaction techniques with a mobile device to simplify 3D interactions for medical imaging specialists. We discuss preliminary observations from our design sessions with medical imaging specialists …

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A Quantitative Analysis Of Decision Process In Social Groups Using Human Trajectories, Truc Viet Le, Siyuan Liu, Hoong Chuin Lau, Ramayya Krishnan May 2014

A Quantitative Analysis Of Decision Process In Social Groups Using Human Trajectories, Truc Viet Le, Siyuan Liu, Hoong Chuin Lau, Ramayya Krishnan

Research Collection School Of Computing and Information Systems

A group's collective action is an outcome of the group's decision-making process, which may be reached by either averaging of the individual preferences or following the choices of certain members in the group. Our problem here is to decide which decision process the group has adopted given the data of the collective actions. We propose a generic statistical framework to infer the group's decision process from the spatio-temporal data of group trajectories, where each "trajectory" is a sequence of group actions. This is achieved by systematically comparing each agent type's influence on the group actions based on an array of …

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Didn’T You See My Message?: Predicting Attentiveness To Mobile Instant Messages, Martin Pielot, Rodrigo De Oliveira, Haewoon Kwak, Nuria. Oliver May 2014

Didn’T You See My Message?: Predicting Attentiveness To Mobile Instant Messages, Martin Pielot, Rodrigo De Oliveira, Haewoon Kwak, Nuria. Oliver

Research Collection School Of Computing and Information Systems

Mobile instant messaging (e.g., via SMS or WhatsApp) often goes along with an expectation of high attentiveness, i.e., that the receiver will notice and read the message within a few minutes. Hence, existing instant messaging services for mobile phones share indicators of availability, such as the last time the user has been online. However, in this paper we not only provide evidence that these cues create social pressure, but that they are also weak predictors of attentiveness. As remedy, we propose to share a machine-computed prediction of whether the user will view a message within the next few minutes or …

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Simple Effective Named Entity Recognition For Microblogs: Arabic As An Example, Kareem Darwish, Wei Gao May 2014

Simple Effective Named Entity Recognition For Microblogs: Arabic As An Example, Kareem Darwish, Wei Gao

Research Collection School Of Computing and Information Systems

No abstract provided.

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