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Articles 6361 - 6390 of 9024

Full-Text Articles in Computer Sciences

Sampled Fictitious Play For Multi-Action Stochastic Dynamic Programs, Archis Ghate, Shih-Fen Cheng, Stephen Baumert, Daniel Reaume, Dushyant Sharma, Robert L. Smith Mar 2014

Sampled Fictitious Play For Multi-Action Stochastic Dynamic Programs, Archis Ghate, Shih-Fen Cheng, Stephen Baumert, Daniel Reaume, Dushyant Sharma, Robert L. Smith

Research Collection School Of Computing and Information Systems

We introduce a class of finite-horizon dynamic optimization problems that we call multi-action stochastic dynamic programs (DPs). Their distinguishing feature is that the decision in each state is a multi-dimensional vector. These problems can in principle be solved using Bellman's backward recursion. However, complexity of this procedure grows exponentially in the dimension of the decision vectors. This is called the curse of action-space dimensionality. To overcome this computational challenge, we propose an approximation algorithm rooted in the game theoretic paradigm of Sampled Fictitious Play (SFP). SFP solves a sequence of DPs with a one-dimensional action-space, which are exponentially smaller than …

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On Predicting User Affiliations Using Social Features In Online Social Networks, Minh Thap Nguyen Mar 2014

On Predicting User Affiliations Using Social Features In Online Social Networks, Minh Thap Nguyen

Dissertations and Theses Collection (Open Access)

User profiling such as user affiliation prediction in online social network is a challenging task, with many important applications in targeted marketing and personalized recommendation. The research task here is to predict some user affiliation attributes that suggest user participation in different social groups.

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Information-Theoretic Multi-View Domain Adaptation: A Theoretical And Empirical Study, Pei Yang, Wei Gao Mar 2014

Information-Theoretic Multi-View Domain Adaptation: A Theoretical And Empirical Study, Pei Yang, Wei Gao

Research Collection School Of Computing and Information Systems

Multi-view learning aims to improve classification performance by leveraging the consistency among different views of data. The incorporation of multiple views was paid little attention in the studies of domain adaptation, where the view consistency based on source data is largely violated in the target domain due to the distribution gap between different domain data. In this paper, we leverage multiple views for cross-domain document classification. The central idea is to strengthen the views' consistency on target data by identifying the associations of domain-specific features from different domains. We present an Information-theoretic Multi-view Adaptation Model (IMAM) using a multi-way clustering …

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A Comparative Study On The Effectiveness Of Part-Of-Speech Tagging Techniques On Bug Reports, Yuan Tian, David Lo Mar 2014

A Comparative Study On The Effectiveness Of Part-Of-Speech Tagging Techniques On Bug Reports, Yuan Tian, David Lo

Research Collection School Of Computing and Information Systems

Many software artifacts are written in natural language or contain substantial amount of natural language contents. Thus these artifacts could be analyzed using text analysis techniques from the natural language processing (NLP) community, e.g., the part-of-speech (POS) tagging technique that assigns POS tags (e.g., verb, noun, etc.) to words in a sentence. In the literature, several studies have already applied POS tagging technique on software artifacts to recover important words in them, which are then used for automating various tasks, e.g., locating buggy files for a given bug report, etc. There are many POS tagging techniques proposed and they are …

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Ropsteg: Program Steganography With Return Oriented Programming, Kangjie Lu, Siyang Xiong, Debin Gao Mar 2014

Ropsteg: Program Steganography With Return Oriented Programming, Kangjie Lu, Siyang Xiong, Debin Gao

Research Collection School Of Computing and Information Systems

Many software obfuscation techniques have been proposed to hide program instructions or logic and to make reverse engineering hard. In this paper, we introduce a new property in software obfuscation, namely program steganography, where certain instructions are "diffused" in others in such a way that they are non-existent until program execution. Program steganography does not raise suspicion in program analysis, and conforms to the W⊕X and mandatory code signing security mechanisms. We further implement RopSteg, a novel software obfuscation system, to provide (to a certain degree) program steganography using return-oriented programming. We apply RopSteg to eight Windows executables and evaluate …

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Keystroke Biometrics: The User Perspective, Chee Meng Tey, Payas Gupta, Kartik Muralidaran, Debin Gao Mar 2014

Keystroke Biometrics: The User Perspective, Chee Meng Tey, Payas Gupta, Kartik Muralidaran, Debin Gao

Research Collection School Of Computing and Information Systems

Usability is an important aspect of security, because poor usability motivates users to find shortcuts that bypass the system. Existing studies on keystroke biometrics evaluate the usability issue in terms of the average false rejection rate (FRR). We show in this paper that such an approach underestimates the user impact in two ways. First, the FRR of keystroke biometrics changes for the worse under a range of common conditions such as background music, exercise and even game playing. In a user study involving 111 participants, the average penalties (increases) in FRR are 0.0360 and 0.0498, respectively, for two different classifiers. …

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Theorems About Quadrilaterals And Conics, Dorde Baralic, Branko Grbic, Dorde Zikelic Mar 2014

Theorems About Quadrilaterals And Conics, Dorde Baralic, Branko Grbic, Dorde Zikelic

Research Collection School Of Computing and Information Systems

We study quadrilaterals inscribed and circumscribed about conics and prove interesting theorems. Theorems are discovered by experimenting with dynamical geometry software. The Poncelet theorem for quadrilaterals is proved by elementary means together with Poncelet's grid property.

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L-Opacity: Linkage-Aware Graph Anonymization, Sadegh Nobari, Panagiotis Karras, Hwee Hwa Pang, Stephane Bressan Mar 2014

L-Opacity: Linkage-Aware Graph Anonymization, Sadegh Nobari, Panagiotis Karras, Hwee Hwa Pang, Stephane Bressan

Research Collection School Of Computing and Information Systems

The wealth of information contained in online social networks has created a demand for the publication of such data as graphs. Yet, publication, even after identities have been removed, poses a privacy threat. Past research has suggested ways to publish graph data in a way that prevents the re-identification of nodes. However, even when identities are effectively hidden, an adversary may still be able to infer linkage between individuals with sufficiently high confidence. In this paper, we focus on the privacy threat arising from such link disclosure. We suggest L-opacity, a sufficiently strong privacy model that aims to control an …

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An Active Resource Orchestration Framework For Pan-Scale Sensor-Rich Environments, Youngki Lee, Chulhong Min, Younghyun Ju, Seungwoo Kang, Yunseok Rhee, Junehwa Song Mar 2014

An Active Resource Orchestration Framework For Pan-Scale Sensor-Rich Environments, Youngki Lee, Chulhong Min, Younghyun Ju, Seungwoo Kang, Yunseok Rhee, Junehwa Song

Research Collection School Of Computing and Information Systems

In this paper, we present Orchestrator, an active resource orchestration framework for a PAN-scale sensor-rich mobile computing platform. Incorporating diverse sensing devices connected to a mobile phone, the platform will serve as a common base to accommodate personal context-aware applications. A major challenge for the platform is to simultaneously support concurrent applications requiring continuous and complex context processing, with highly scarce and dynamic resources. To address the challenge, we build Orchestrator, which actively coordinates applications' resource uses over the distributed mobile and sensor devices. As a key approach, it adopts an active resource use orchestration, which prepares multiple alternative plans …

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Online Feature Selection And Its Applications, Jialei Wang, Peilin Zhao, Steven C. H. Hoi, Rong Jin Mar 2014

Online Feature Selection And Its Applications, Jialei Wang, Peilin Zhao, Steven C. H. Hoi, Rong Jin

Research Collection School Of Computing and Information Systems

Feature selection is an important technique for data mining. Despite its importance, most studies of feature selection are restricted to batch learning. Unlike traditional batch learning methods, online learning represents a promising family of efficient and scalable machine learning algorithms for large-scale applications. Most existing studies of online learning require accessing all the attributes/features of training instances. Such a classical setting is not always appropriate for real-world applications when data instances are of high dimensionality or it is expensive to acquire the full set of attributes/features. To address this limitation, we investigate the problem of online feature selection (OFS) in …

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Retrieval-Based Face Annotation By Weak Label Regularized Local Coordinate Coding, Dayong Wang, Steven C. H. Hoi, Ying He, Jianke Zhu, Mei Tao, Jiebo Luo Mar 2014

Retrieval-Based Face Annotation By Weak Label Regularized Local Coordinate Coding, Dayong Wang, Steven C. H. Hoi, Ying He, Jianke Zhu, Mei Tao, Jiebo Luo

Research Collection School Of Computing and Information Systems

Auto face annotation, which aims to detect human faces from a facial image and assign them proper human names, is a fundamental research problem and beneficial to many real-world applications. In this work, we address this problem by investigating a retrieval-based annotation scheme of mining massive web facial images that are freely available over the Internet. In particular, given a facial image, we first retrieve the top n similar instances from a large-scale web facial image database using content-based image retrieval techniques, and then use their labels for auto annotation. Such a scheme has two major challenges: 1) how to …

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Teaching Tip: The Flipped Classroom, Heng Ngee Mok Mar 2014

Teaching Tip: The Flipped Classroom, Heng Ngee Mok

Research Collection School Of Computing and Information Systems

The flipped classroom has been gaining popularity in recent years. In theory, flipping the classroom appears sound: passive learning activities such as unidirectional lectures are pushed to outside class hours in the form of videos, and precious class time is spent on active learning activities. Yet the courses for information systems (IS) undergraduates at the university that the author is teaching at are still conducted in the traditional lecture-in-class, homework-after-class style. In order to increase students’ engagement with the course content and to improve their experience with the course, the author implemented a trial of the flipped classroom model for …

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Time-Series Data Mining In Transportation: A Case Study On Singapore Public Train Commuter Travel Patterns, Tin Seong Kam, Roy Ka Wei Lee Mar 2014

Time-Series Data Mining In Transportation: A Case Study On Singapore Public Train Commuter Travel Patterns, Tin Seong Kam, Roy Ka Wei Lee

Research Collection School Of Computing and Information Systems

The adoption of smart cards technologies and automated data collection systems (ADCS) in transportation domain had provided public transport planners opportunities to amass a huge and continuously increasing amount of time-series data about the behaviors and travel patterns of commuters. However the explosive growth of temporal related databases has far outpaced the transport planners’ ability to interpret these data using conventional statistical techniques, creating an urgent need for new techniques to support the analyst in transforming the data into actionable information and knowledge. This research study thus explores and discusses the potential use of time-series data mining, a relatively new …

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Social Correlation In Latent Spaces For Complex Networks, Freddy Chong Tat Chua Feb 2014

Social Correlation In Latent Spaces For Complex Networks, Freddy Chong Tat Chua

Dissertations and Theses Collection (Open Access)

This dissertation addresses the subject of measuring social correlation among users within a complex social network. Social correlation is closely related to the measurement of social influence in social sciences. While social influence focuses on the existence of causal influence among users, we take a computational approach to measure correlation strength among users based on their shared interactions. We call this social correlation. To formally model social correlation, we propose a framework which contains two major parts. The first part is that of representing users behavior in a computationally efficient and accurate manner. For example, social media users perform many …

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Pricing Strategy For Cloud Computing Services, Jianhui Huang Feb 2014

Pricing Strategy For Cloud Computing Services, Jianhui Huang

Dissertations and Theses Collection (Open Access)

The cloud computing services market exhibits unique characteristics such as instant accessibility, fluctuating demand and supply, and interruptible service provision. Various pricing mechanisms exist in current industry practice. None of these pricing mechanisms, however, is comprehensive enough to capture all these features in a way that allows the vendors to optimize resource allocation. This dissertation identifies key factors related to cloud computing pricing, and examines their interplays. This research uses multiple approaches, including a market survey, game theory modeling, simulation, lab experiments and econometric modeling, to analyze the pricing strategy of cloud services vendors. A field study of a representative …

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Building Thinc: User Incentivization And Meeting Rescheduling For Energy Savings, Jun Young Kwak, Debarun Kar, William Haskell, Pradeep Reddy Varakantham, Milind Tambe Feb 2014

Building Thinc: User Incentivization And Meeting Rescheduling For Energy Savings, Jun Young Kwak, Debarun Kar, William Haskell, Pradeep Reddy Varakantham, Milind Tambe

Research Collection School Of Computing and Information Systems

This paper presents THINC, an agent developed for saving energy in real-world commercial buildings. While previous work has presented techniques for computing energy-efficient schedules, it fails to address two issues, centered on human users, that are essential in real-world agent deployments: (i) incentivizing users for their energy saving activities and (ii) interacting with users to reschedule key “energy-consuming” meetings in a timely fashion, while handling the uncertainty in such interactions. THINC addresses these shortcomings by providing four new major contributions. First, THINC computes fair division of credits from energy savings. For this fair division, THINC provides novel algorithmic advances for …

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Los And Nlos Classification For Underwater Acoustic Localization, Roee Diamant, Hwee-Pink Tan, Lutz Lampe Feb 2014

Los And Nlos Classification For Underwater Acoustic Localization, Roee Diamant, Hwee-Pink Tan, Lutz Lampe

Research Collection School Of Computing and Information Systems

The low sound speed in water makes propagation delay (PD)-based range estimation attractive for underwater acoustic localization (UWAL). However, due to the long channel impulse response and the existence of reflectors, PD-based UWAL suffers from significant degradation when PD measurements of nonline-of-sight (NLOS) communication links are falsely identified as line-of-sight (LOS). In this paper, we utilize expected variation of PD measurements due to mobility of nodes and present an algorithm to classify the former into LOS and NLOS links. First, by comparing signal strength-based and PD-based range measurements, we identify object-related NLOS (ONLOS) links, where signals are reflected from objects …

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Automated Construction Of A Software-Specific Word Similarity Database, Yuan Tian, David Lo, Julia Lawall Feb 2014

Automated Construction Of A Software-Specific Word Similarity Database, Yuan Tian, David Lo, Julia Lawall

Research Collection School Of Computing and Information Systems

Many automated software engineering approaches, including code search, bug report categorization, and duplicate bug report detection, measure similarities between two documents by analyzing natural language contents. Often different words are used to express the same meaning and thus measuring similarities using exact matching of words is insufficient. To solve this problem, past studies have shown the need to measure the similarities between pairs of words. To meet this need, the natural language processing community has built WordNet which is a manually constructed lexical database that records semantic relations among words and can be used to measure how similar two words …

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Towards More Accurate Multi-Label Software Behavior Learning, Xin Xia, Feng Yang, David Lo, Zhenyu Chen, Xinyu Wang Feb 2014

Towards More Accurate Multi-Label Software Behavior Learning, Xin Xia, Feng Yang, David Lo, Zhenyu Chen, Xinyu Wang

Research Collection School Of Computing and Information Systems

In a modern software system, when a program fails, a crash report which contains an execution trace would be sent to the software vendor for diagnosis. A crash report which corresponds to a failure could be caused by multiple types of faults simultaneously. Many large companies such as Baidu organize a team to analyze these failures, and classify them into multiple labels (i.e., multiple types of faults). However, it would be time-consuming and difficult for developers to manually analyze these failures and come out with appropriate fault labels. In this paper, we automatically classify a failure into multiple types of …

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An Empirical Study Of Bug Report Field Reassignment, Xin Xia, David Lo, Ming Wen, Shihab Emad, Bo Zhou Feb 2014

An Empirical Study Of Bug Report Field Reassignment, Xin Xia, David Lo, Ming Wen, Shihab Emad, Bo Zhou

Research Collection School Of Computing and Information Systems

A bug report contains many fields, such as product, component, severity, priority, fixer, operating system (OS), platform, etc., which provide important information for the bug triaging and fixing process. It is important to make sure that bug information is correct since previous studies showed that the wrong assignment of bug report fields could increase the bug fixing time, and even delay the delivery of the software. In this paper, we perform an empirical study on bug report field reassignments in open-source software projects. To better understand why bug report fields are reassigned, we manually collect 99 recent bug reports that …

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Integrating Water Exclusion Theory Into Β Contacts To Predict Binding Free Energy Changes And Binding Hot Spots, Qian Liu, Steven C. H. Hoi, Chee Keong Kwoh, Limsoon Wong, Jinyan Li Feb 2014

Integrating Water Exclusion Theory Into Β Contacts To Predict Binding Free Energy Changes And Binding Hot Spots, Qian Liu, Steven C. H. Hoi, Chee Keong Kwoh, Limsoon Wong, Jinyan Li

Research Collection School Of Computing and Information Systems

Binding free energy and binding hot spots at protein-protein interfaces are two important research areas for understanding protein interactions. Computational methods have been developed previously for accurate prediction of binding free energy change upon mutation for interfacial residues. However, a large number of interrupted and unimportant atomic contacts are used in the training phase which caused accuracy loss. Results: This work proposes a new method, β ACV ASA , to predict the change of binding free energy after alanine mutations. β ACV ASA integrates accessible surface area (ASA) and our newly defined β contacts together into an atomic contact vector …

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Integrating Water Exclusion Theory Into Β Contacts To Predict Binding Free Energy Changes And Binding Hot Spots, Qian Liu, Steven C. H. Hoi, Chee Keong Kwoh, Limsoon Wong, Jinyan Li Feb 2014

Integrating Water Exclusion Theory Into Β Contacts To Predict Binding Free Energy Changes And Binding Hot Spots, Qian Liu, Steven C. H. Hoi, Chee Keong Kwoh, Limsoon Wong, Jinyan Li

Research Collection School Of Computing and Information Systems

Binding free energy and binding hot spots at protein-protein interfaces are two important research areas for understanding protein interactions. Computational methods have been developed previously for accurate prediction of binding free energy change upon mutation for interfacial residues. However, a large number of interrupted and unimportant atomic contacts are used in the training phase which caused accuracy loss. Results: This work proposes a new method, β ACV ASA , to predict the change of binding free energy after alanine mutations. β ACV ASA integrates accessible surface area (ASA) and our newly defined β contacts together into an atomic contact vector …

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Democracy Is Good For Ranking: Towards Multi-View Rank Learning And Adaptation In Web Search, Wei Gao, Pei Yang Feb 2014

Democracy Is Good For Ranking: Towards Multi-View Rank Learning And Adaptation In Web Search, Wei Gao, Pei Yang

Research Collection School Of Computing and Information Systems

No abstract provided.

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Visual Typo Correction By Collocative Optimization: A Case Study On Merchandize Images, Xiao-Yong Wei, Zhen-Qun Yang, Chong-Wah Ngo, Wei Zhang Feb 2014

Visual Typo Correction By Collocative Optimization: A Case Study On Merchandize Images, Xiao-Yong Wei, Zhen-Qun Yang, Chong-Wah Ngo, Wei Zhang

Research Collection School Of Computing and Information Systems

Near-duplicate retrieval (NDR) in merchandize images is of great importance to a lot of online applications on e-Commerce websites. In those applications where the requirement of response time is critical, however, the conventional techniques developed for a general purpose NDR are limited, because expensive post-processing like spatial verification or hashing is usually employed to compromise the quantization errors among the visual words used for the images. In this paper, we argue that most of the errors are introduced because of the quantization process where the visual words are considered individually, which has ignored the contextual relations among words. We propose …

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Identity Based Identification From Algebraic Coding Theory, Guomin Yang, Chik How Tan, Yi Mu, Willy Susilo, Duncan S. Wong Feb 2014

Identity Based Identification From Algebraic Coding Theory, Guomin Yang, Chik How Tan, Yi Mu, Willy Susilo, Duncan S. Wong

Research Collection School Of Computing and Information Systems

Cryptographic identification schemes allow a remote user to prove his/her identity to a verifier who holds some public information of the user, such as the user public key or identity. Most of the existing cryptographic identification schemes are based on numbertheoretic hard problems such as Discrete Log and Factorization. This paper focuses on the design and analysis of identity based identification (IBI) schemes based on algebraic coding theory. We first revisit an existing code-based IBI scheme which is derived by combining the Courtois–Finiasz–Sendrier signature scheme and the Stern zero-knowledge identification scheme. Previous results have shown that this IBI scheme is …

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Libol: A Library For Online Learning Algorithms, Steven C. H. Hoi, Jialei Wang, Peilin Zhao Feb 2014

Libol: A Library For Online Learning Algorithms, Steven C. H. Hoi, Jialei Wang, Peilin Zhao

Research Collection School Of Computing and Information Systems

LIBOL is an open-source library for large-scale online learning, which consists of a large family of efficient and scalable state-of-the-art online learning algorithms for large- scale online classification tasks. We have offered easy-to-use command-line tools and examples for users and developers, and also have made comprehensive documents available for both beginners and advanced users. LIBOL is not only a machine learning toolbox, but also a comprehensive experimental platform for conducting online learning research.

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Sketch: Pen And Touch Recognition [Workshop Summary], Richard C. Davis, Aaron Adler Feb 2014

Sketch: Pen And Touch Recognition [Workshop Summary], Richard C. Davis, Aaron Adler

Research Collection School Of Computing and Information Systems

Sketch recognition has technically been around for 40 years, but it has come and gone several times due to the difficulty of the problem. With the rise of touch and pen enabled phones and tablets, sketch recognition is regaining popularity and public presence, and more people are becoming aware of and interested in this difficult, but valuable, problem. It is important to harness the Sketch Recognition community at this time to encourage the flourishing of this topic.

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Key-Aggregate Cryptosystem For Scalable Data Sharing In Cloud Storage, Cheng-Kang Chu, Sherman S. M. Chow, Wen-Guey Tzeng, Jiangying Zhou, Robert H. Deng Feb 2014

Key-Aggregate Cryptosystem For Scalable Data Sharing In Cloud Storage, Cheng-Kang Chu, Sherman S. M. Chow, Wen-Guey Tzeng, Jiangying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

Data sharing is an important functionality in cloud storage. In this article, we show how to securely, efficiently, and flexibly share data with others in cloud storage. We describe new public-key cryptosystems which produce constant-size ciphertexts such that efficient delegation of decryption rights for any set of ciphertexts are possible. The novelty is that one can aggregate any set of secret keys and make them as compact as a single key, but encompassing the power of all the keys being aggregated. In other words, the secret key holder can release a constant-size aggregate key for flexible choices of ciphertext set …

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Ropecker: A Generic And Practical Approach For Defending Against Rop Attack, Yueqiang Cheng, Zongwei Zhou, Yu Miao, Xuhua Ding, Robert H. Deng Feb 2014

Ropecker: A Generic And Practical Approach For Defending Against Rop Attack, Yueqiang Cheng, Zongwei Zhou, Yu Miao, Xuhua Ding, Robert H. Deng

Research Collection School Of Computing and Information Systems

Return-Oriented Programming (ROP) is a sophisticated exploitation technique that is able to drive target applications to perform arbitrary unintended operations by constructing a gadget chain reusing existing small code sequences (gadgets). Existing defense mechanisms either only handle specific types of gadgets, require access to source code and/or a customized compiler, break the integrity of application binary, or suffer from high performance overhead. In this paper, we present a novel system, ROPecker, to efficiently and effectively defend against ROP attacks without relying on any other side information (e.g., source code and compiler support) or binary rewriting. ROPecker detects an ROP attack …

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Sinabro: Opportunistic And Unobtrusive Mobile Ecg Monitoring System, Seungwoo Kang, Sungjun Kwon, Sangwon Seo, Chungkuk Yoo, Kwangsuk Park, Junehwa Song, Youngki Lee Feb 2014

Sinabro: Opportunistic And Unobtrusive Mobile Ecg Monitoring System, Seungwoo Kang, Sungjun Kwon, Sangwon Seo, Chungkuk Yoo, Kwangsuk Park, Junehwa Song, Youngki Lee

Research Collection School Of Computing and Information Systems

In this paper, we propose Sinabro, an opportunistic and unobtrusive mobile electrocardiogram (ECG) monitoring system that monitors the user’s ECG opportunistically during daily smartphone use. Daily ECG monitoring will open up an unprecedented opportunity for pervasive healthcare applications. It will enable the daily detection and prevention of heart problems and also allow inferences about stress, emotion, and even sleep quality. Despite its huge potential, daily ECG monitoring still has not become reality due to its obtrusiveness. In this paper, we first study the potential opportunity to capture ECGs from daily use of smartphones, without requiring the user’s explicit attention. Based …

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