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Full-Text Articles in Computer Sciences

Spatio-Temporal Efficiency In A Taxi Dispatch System, Darshan Santani, Rajesh Krishna Balan, C. Jason Woodard Oct 2008

Spatio-Temporal Efficiency In A Taxi Dispatch System, Darshan Santani, Rajesh Krishna Balan, C. Jason Woodard

Research Collection School Of Computing and Information Systems

In this paper, we present an empirical analysis of the GPS-enabled taxi dispatch system used by the world’s second largest land transportation company. We first summarize the collective dynamics of the more than 6,000 taxicabs in this fleet. Next, we propose a simple method for evaluating the efficiency of the system over a given period of time and geographic zone. Our method yields valuable insights into system performance—in particular, revealing significant inefficiencies that should command the attention of the fleet operator. For example, despite the state of the art dispatching system employed by the company, we find imbalances in supply …


Spreadsheet Data Resampling For Monte-Carlo Simulation, Thin Yin Leong, Wee Leong Lee Oct 2008

Spreadsheet Data Resampling For Monte-Carlo Simulation, Thin Yin Leong, Wee Leong Lee

Research Collection School Of Computing and Information Systems

The pervasiveness of spreadsheets software resulted in its increased application as a simulation tool for business analysis. Random values generation supporting such evaluations using spreadsheets are simple and yet powerful. However, the typical approach to Monte-Carlo simulations, which is what simulations with stochasticity are called, requires significant amount of time to be spent on data collection, data collation, and distribution function fitting. In fact, the latter can be overwhelming for undergraduate students to learn and do properly in a short time. Resampling eliminates both the need to fit distributions to the sample data, and to perform the ensuing tests of …


Generating Robust Schedules Subject To Resource And Duration Uncertainties, Na Fu, Hoong Chuin Lau, Fei Xiao Sep 2008

Generating Robust Schedules Subject To Resource And Duration Uncertainties, Na Fu, Hoong Chuin Lau, Fei Xiao

Research Collection School Of Computing and Information Systems

We consider the Resource-Constrained Project Scheduling Problem with minimal and maximal time lags under resource and duration uncertainties. To manage resource uncertainties, we build upon the work of Lambrechts et al 2007 and develop a method to analyze the effect of resource breakdowns on activity durations. We then extend the robust local search framework of Lau et al 2007 with additional considerations on the impact of unexpected resource breakdowns to the project makespan, so that partial order schedules (POS) can absorb both resource and duration uncertainties. Experiments show that our proposed model is capable of addressing the uncertainty of resources, …


Special Issue Introduction: Hci Studies In Mis, Fiona Fui-Hoon Nah, Xiaowen Fang, Traci Hess, Weiyin Hong Sep 2008

Special Issue Introduction: Hci Studies In Mis, Fiona Fui-Hoon Nah, Xiaowen Fang, Traci Hess, Weiyin Hong

Research Collection School Of Computing and Information Systems

We are grateful to the editors-in-chief for this opportunity and their strong support of the second AIS SIGHCI-sponsored special issue on HCI studies in MIS. We also thank the following reviewers who have played an important role in the development of the manuscripts included in this special issue: Steven Bellman, Damon Campbell, Jinwei Cao, Jane Carey, Andrea Everard, Mark Fuller, Matt Germonprez, Maggie Guo, Susanna Ho, De Liu, Hong Sheng, Chuan Hoo Tan, Horst Treiblmaier, June Wei, and Yunjie Calvin Xu.


Tuning Into The Digital Channel: Evaluating Business Model Fit For Internet Firm Survival, Robert J. Kauffman, Bin Wang Sep 2008

Tuning Into The Digital Channel: Evaluating Business Model Fit For Internet Firm Survival, Robert J. Kauffman, Bin Wang

Research Collection School Of Computing and Information Systems

More than 5,000 Internet firms have failed since the beginning of 2000. One common perception is that the downturn in the economy drove many firms out of business. But then, why have some firms survived? In this research, we provide an empirical analysis by examining how the business model characteristics of an Internet firm affect its survival. We analyze a panel data set of 130 public Internet firms using two different techniques: non-parametric survival analysis, and the semiparametric Cox proportional hazards model. We characterize the survival rates throughout the lifetimes of the public Internet firms in our sample. Our results …


Software Nightmares, Manoj Thulasidas Sep 2008

Software Nightmares, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

To err is human, but to really foul things up, you need a computer. So states the remarkably insightful Murphy’s Law. And nowhere else does this ring truer than in our financial workplace. After all, it is the financial sector that drove the rapid progress in the computing industry – which is why the first computing giant had the word “business” in its name. The financial industry keeps up with the developments in the computer industry for one simple reason. Stronger computers and smarter programs mean more money — a concept we readily grasp. As we use the latest and …


Cascade Rsvm In Peer-To-Peer Network, Hock Hee Ang, Vivekanand Gopalkrishnan, Steven C. H. Hoi, Wee Keong Ng Sep 2008

Cascade Rsvm In Peer-To-Peer Network, Hock Hee Ang, Vivekanand Gopalkrishnan, Steven C. H. Hoi, Wee Keong Ng

Research Collection School Of Computing and Information Systems

The goal of distributed learning in P2P networks is to achieve results as close as possible to those from centralized approaches. Learning models of classification in a P2P network faces several challenges like scalability, peer dynamism, asynchronism and data privacy preservation. In this paper, we study the feasibility of building SVM classifiers in a P2P network. We show how cascading SVM can be mapped to a P2P network of data propagation. Our proposed P2P SVM provides a method for constructing classifiers in P2P networks with classification accuracy comparable to centralized classifiers and better than other distributed classifiers. The proposed algorithm …


Relative Importance, Specific Investment And Ownership In Interorganizational Systems., Kunsoo Han, Robert J. Kauffman, Barrie R. Nault Sep 2008

Relative Importance, Specific Investment And Ownership In Interorganizational Systems., Kunsoo Han, Robert J. Kauffman, Barrie R. Nault

Research Collection School Of Computing and Information Systems

Implementation and maintenance of interorganizational systems (IOS) require investments by all the participating firms. Compared with intraorganizational systems, however, there are additional uncertainties and risks. This is because the benefits of IOS investment depend not only on a firm's own decisions, but also on those of its business partners. Without appropriate levels of investment by all the firms participating in an IOS, they cannot reap the full benefits. Drawing upon the literature in institutional economics, we examine IOS ownership as a means to induce value-maximizing noncontractible investments. We model the impact of two factors derived from the theory of incomplete …


Tagnsearch: Searching And Navigating Geo-Referenced Collections Of Photographs, Quang Minh Nguyen, Thi Nhu Quynh Kim, Dion Hoe-Lian Goh, Yin-Leng Theng, Ee Peng Lim, Aixin Sun, Chew-Hung Chang, Kalyani Chatterjea Sep 2008

Tagnsearch: Searching And Navigating Geo-Referenced Collections Of Photographs, Quang Minh Nguyen, Thi Nhu Quynh Kim, Dion Hoe-Lian Goh, Yin-Leng Theng, Ee Peng Lim, Aixin Sun, Chew-Hung Chang, Kalyani Chatterjea

Research Collection School Of Computing and Information Systems

TagNSearch is a map-based tool for searching and browsing geo-tagged photographs based on their associated tags. Using Flickr as the dataset, TagNSearch returns, for a given query, photographs clustered by locations, and summarizes each cluster of photographs by cluster-specific tags. A map-based interface is also provided to help users better search, navigate and browse photographs and their clusters. A qualitative evaluation comparing TagNSearch and an existing tag search support in Flickr was also conducted. The task involved finding locations associated with a set of photographs. Participants were found to perform this task better using TagNSearch than Flickr.


Distinguishing Between Fe And Ddos Using Randomness Check, Hyundo Park, Peng Li, Debin Gao, Heejo Lee, Robert H. Deng Sep 2008

Distinguishing Between Fe And Ddos Using Randomness Check, Hyundo Park, Peng Li, Debin Gao, Heejo Lee, Robert H. Deng

Research Collection School Of Computing and Information Systems

Threads posed by Distributed Denial of Service (DDoS) attacks are becoming more serious day by day. Accurately detecting DDoS becomes an important and necessary step in securing a computer network. However, Flash Event (FE), which is created by legitimate requests, shares very similar characteristics with DDoS in many aspects and makes it hard to be distinguished from DDoS attacks. In this paper, we propose a simple yet effective mechanism called FDD (FE and DDoS Distinguisher) to distinguish FE and DDoS. To the best of our knowledge, this is the first effective and practical mechanism that distinguishes FE and DDoS attacks. …


An Efficient Pir Construction Using Trusted Hardware, Yanjiang Yang, Xuhua Ding, Robert H. Deng, Feng Bao Sep 2008

An Efficient Pir Construction Using Trusted Hardware, Yanjiang Yang, Xuhua Ding, Robert H. Deng, Feng Bao

Research Collection School Of Computing and Information Systems

For a private information retrieval (PIR) scheme to be deployed in practice, low communication complexity and low computation complexity are two fundamental requirements it must meet. Most existing PIR schemes only focus on the communication complexity. The reduction on the computational complexity did not receive the due treatment mainly because of its O(n) lower bound. By using the trusted hardware based model, we design a novel scheme which breaks this barrier. With constant storage, the computation complexity of our scheme, including offline computation, is linear to the number of queries and is bounded by after optimization.


A Heuristic Method For Job-Shop Scheduling With An Infinite Wait Buffer: From One-Machine To Multi-Machine Problems, Z. J. Zhao, J. Kim, M. Luo, Hoong Chuin Lau, S. S. Ge Sep 2008

A Heuristic Method For Job-Shop Scheduling With An Infinite Wait Buffer: From One-Machine To Multi-Machine Problems, Z. J. Zhao, J. Kim, M. Luo, Hoong Chuin Lau, S. S. Ge

Research Collection School Of Computing and Information Systems

Through empirical comparison of classical job shop problems (JSP) with multi-machine consideration, we find that the objective to minimize the sum of weighted tardiness has a better wait property compared with the objective to minimize the makespan. Further, we test the proposed Iterative Minimization Micro-model (IMM) heuristic method with the mixed integer programming (MIP) solution by CPLEX. For multi-machine problems, the IMM heuristic method is faster and achieves a better solution. Finally, for a large problem instance with 409 jobs and 30 types of machines, IMM-heuristic method is compared with ProModel and we find that the heuristic method is slightly …


Do Online Reviews Affect Product Sales? The Role Of Reviewer Characteristics And Temporal Effects, Nan Hu, Ling Liu, Jennifer Zhang Sep 2008

Do Online Reviews Affect Product Sales? The Role Of Reviewer Characteristics And Temporal Effects, Nan Hu, Ling Liu, Jennifer Zhang

Research Collection School Of Computing and Information Systems

Online product reviews provided by consumers who previously purchased products have become a major information source for consumers and marketers regarding product quality. This study extends previous research by conducting a more compelling test of the effect of online reviews on sales. In particular, we consider both quantitative and qualitative aspects of online reviews, such as reviewer quality, reviewer exposure, product coverage, and temporal effects. Using transaction cost economics and uncertainty reduction theories, this study adopts a portfolio approach to assess the effectiveness of the online review market. We show that consumers understand the value difference between favorable news and …


Classification In P2p Networks By Bagging Cascade Rsvms, Hock Hee Ang, Vikvekanand Gopalkrishnan, Steven C. H. Hoi, Wee Keong Ng, Anwitaman Datta Aug 2008

Classification In P2p Networks By Bagging Cascade Rsvms, Hock Hee Ang, Vikvekanand Gopalkrishnan, Steven C. H. Hoi, Wee Keong Ng, Anwitaman Datta

Research Collection School Of Computing and Information Systems

Data mining tasks in P2P are bound by issues like scalability, peer dynamism, asynchronism, and data privacy preservation. These challenges pose difficulties for deploying conventional machine learning techniques in P2P networks, which may be hard to achieve classification accuracies comparable to regular centralized solutions. We recently investigated the classification problem in P2P networks and proposed a novel P2P classification approach by cascading Reduced Support Vector Machines (RSVM). Although promising results were obtained, the existing solution has some drawback of redundancy in both communication and computation. In this paper, we present a new approach to over the limitation of the previous …


Impacts Of Social Network Structure On Knowledge Sharing In Open Source Software Development Teams, Y. Long, Keng Siau Aug 2008

Impacts Of Social Network Structure On Knowledge Sharing In Open Source Software Development Teams, Y. Long, Keng Siau

Research Collection School Of Computing and Information Systems

The study examines the relationship between social network structure and knowledge sharing in Open Source Software (OSS) development teams. One hundred and fifty projects were selected from SourceForge.net using stratified sampling. Social network structure was measured by two indices: degree of centralization and core/periphery fitness. Knowledge sharing was measured from two aspects: the quality of knowledge sharing that is indicated by the helpfulness of messages and the quantity of knowledge sharing that is indicated by the number of messages. The results show that social network structure significantly affects the quantity of knowledge sharing. However, social network structure does not influence …


Mining Patterns And Rules For Software Specification Discovery, David Lo, Siau-Cheng Khoo Aug 2008

Mining Patterns And Rules For Software Specification Discovery, David Lo, Siau-Cheng Khoo

Research Collection School Of Computing and Information Systems

Software specifications are often lacking, incomplete and outdated in the industry. Lack and incomplete specifications cause various software engineering problems. Studies have shown that program comprehension takes up to 45% of software development costs. One of the root causes of the high cost is the lack-of documented specification. Also, outdated and incomplete specification might potentially cause bugs and compatibility issues. In this paper, we describe novel data mining techniques to mine or reverse engineer these specifications from the pool of software engineering data. A large amount of software data is available for analysis. One form of software data is program …


The Pricing Strategy Analysis For The Software-As-A-Service Business Model, Dan Ma, Abraham Seidmann Aug 2008

The Pricing Strategy Analysis For The Software-As-A-Service Business Model, Dan Ma, Abraham Seidmann

Research Collection School Of Computing and Information Systems

The Software-as-a-Service (SaaS) model is a novel way of delivering software applications. In this paper, we present an analytical model to study the competition between the SaaS and the traditional COTS (Commercial off-the-shelf) software. The main research goal is to analyze the pricing strategy of the SaaS in a competitive setting. The model captures the most salient differences between the SaaS and COTS, including their distinct pricing structures, user initial setup costs, system customization levels, and delivery channels. We find that the two could coexist in a competitive market in the long run, and more importantly, we show how the …


Relationship Preserving Auction For Repeated E-Procurement, Park J., Lee J., Lau H. Aug 2008

Relationship Preserving Auction For Repeated E-Procurement, Park J., Lee J., Lau H.

Research Collection School Of Computing and Information Systems

While e-procurement auction has helped firms to achieve lower procurement costs, auction mechanisms that prevail at present in procurement markets need to address an important issue that concerns the ability to maintain long term relationships with the partners, especially in repeated e-procurement settings. In this paper, we propose a Relationship Preserving Auction (RPA) mechanism that augments the conventional auction mechanism with a bidder relationship scoring model. Our proposed mechanism gives increased chances of winning to the bidders who have bidden at relatively competitive price but had comparatively less wins so far. Keeping these bidders in the auction over time will …


Knowledge Transfer Via Multiple Model Local Structure Mapping, Jing Gao, Wei Fan, Jing Jiang, Jiawei Han Aug 2008

Knowledge Transfer Via Multiple Model Local Structure Mapping, Jing Gao, Wei Fan, Jing Jiang, Jiawei Han

Research Collection School Of Computing and Information Systems

The effectiveness of knowledge transfer using classification algorithms depends on the difference between the distribution that generates the training examples and the one from which test examples are to be drawn. The task can be especially difficult when the training examples are from one or several domains different from the test domain. In this paper, we propose a locally weighted ensemble framework to combine multiple models for transfer learning, where the weights are dynamically assigned according to a model's predictive power on each test example. It can integrate the advantages of various learning algorithms and the labeled information from multiple …


Authenticating The Query Results Of Text Search Engines, Hwee Hwa Pang, Kyriakos Mouratidis Aug 2008

Authenticating The Query Results Of Text Search Engines, Hwee Hwa Pang, Kyriakos Mouratidis

Research Collection School Of Computing and Information Systems

The number of successful attacks on the Internet shows that it is very difficult to guarantee the security of online search engines. A breached server that is not detected in time may return incorrect results to the users. To prevent that, we introduce a methodology for generating an integrity proof for each search result. Our solution is targeted at search engines that perform similarity-based document retrieval, and utilize an inverted list implementation (as most search engines do). We formulate the properties that define a correct result, map the task of processing a text search query to adaptations of existing threshold-based …


Simulating A Smartboard By Real-Time Gesture Detection In Lecture Videos, Feng Wang, Chong-Wah Ngo, Ting-Chuen Pong Aug 2008

Simulating A Smartboard By Real-Time Gesture Detection In Lecture Videos, Feng Wang, Chong-Wah Ngo, Ting-Chuen Pong

Research Collection School Of Computing and Information Systems

Gesture plays an important role for recognizing lecture activities in video content analysis. In this paper, we propose a real-time gesture detection algorithm by integrating cues from visual, speech and electronic slides. In contrast to the conventional "complete gesture" recognition, we emphasize detection by the prediction from "incomplete gesture". Specifically, intentional gestures are predicted by the modified hidden Markov model (HMM) which can recognize incomplete gestures before the whole gesture paths are observed. The multimodal correspondence between speech and gesture is exploited to increase the accuracy and responsiveness of gesture detection. In lecture presentation, this algorithm enables the on-the-fly editing …


Hierarchical Inter-Object Traces For Specification Mining, David Lo, Shahar Maoz Aug 2008

Hierarchical Inter-Object Traces For Specification Mining, David Lo, Shahar Maoz

Research Collection School Of Computing and Information Systems

Major challenges of dynamic analysis approaches to specification mining include scalability over long traces as well as comprehensibility and expressivity of results. We present a novel use of object hierarchies over inter-object traces as an abstraction/refinement mechanism enabling scalable, incremental, top-down mining of scenario-based specifications.


Critical Success Factors In Soa Implementation, J. Erickson, Keng Siau Aug 2008

Critical Success Factors In Soa Implementation, J. Erickson, Keng Siau

Research Collection School Of Computing and Information Systems

Service Oriented Architecture (SOA) has become flavor du jour for many businesses. Seemingly, almost every company has implemented, is in the midst of implementing or is seriously considering a SOA project. A critical question many organizations are facing now is – what are the critical success factors for SOA implementations? This research aims to identify a list of factors relating to SOA implementation success. A Delphi study forms the research method, and inputs regarding SOA critical success factors are requested from a panel of experts.


Integrating Lightweight Systems Analysis Into The Unified Process By Using Service Responsibility Tables, X. Tan, S. Alter, Keng Siau Aug 2008

Integrating Lightweight Systems Analysis Into The Unified Process By Using Service Responsibility Tables, X. Tan, S. Alter, Keng Siau

Research Collection School Of Computing and Information Systems

This paper is a step toward establishing direct, but non-automatic links between lightweight (semi-formal) analysis methods for business professionals and heavyweight analysis methods for IT professionals. After noting the importance of user involvement in obtaining accurate and meaningful user requirements, the paper summarizes the Unified Process, a software development methodology that employs Unified Modeling Language (UML). Another section in the paper summarizes previous extensions of the work system method that produced a lightweight analysis tool called Service Responsibility Tables (SRTs). This paper uses a straightforward example to demonstrate a set of heuristics for translating between service responsibility tables produced by …


Understanding Factors Influencing Proficient Information Systems Usage, Brenda Eschenbrenner, Fiona Fui-Hoon Nah Aug 2008

Understanding Factors Influencing Proficient Information Systems Usage, Brenda Eschenbrenner, Fiona Fui-Hoon Nah

Research Collection School Of Computing and Information Systems

Variations exist among information system (IS) users’ abilities to effectively utilize an IS. Some users are able to maximize IS potential, while others are not. This research proposes to understand the attributes of individuals who are most capable of exploiting IS to its fullest potential as well as the management and organizational factors that facilitate the development of highly competent users. The Repertory Grid Technique was utilized to identify user attributes contributing to IS proficiency in Phase One of this research and will be utilized to identify management and organizational factors in Phase Two. The results will provide a comprehensive …


Learning Outcomes For A Business Information Systems Undergraduate Program, Joelle Elmaleh, Steven Miller, Paul S. Goodman Aug 2008

Learning Outcomes For A Business Information Systems Undergraduate Program, Joelle Elmaleh, Steven Miller, Paul S. Goodman

Research Collection School Of Computing and Information Systems

We present a learning outcomes framework for an Information Systems (IS) undergraduate program. This framework includes a supporting software application that goes beyond any other attempt reported to date to integrate learning outcomes into program-wide and course-wide curriculum development, ongoing curriculum redesign, and student learning support. The Learning Outcomes Management System (LOMS) described here is a first-of-a-kind information system created as part of implementing a program-wide learning outcomes framework in a university setting. Our learning outcomes framework is distinct in that 1) it is based on a three-level hierarchically structured definition of learning outcomes that consistently apply to both the …


A Lightweight Buyer-Seller Watermarking Protocol, Yongdong Wu, Hwee Hwa Pang Aug 2008

A Lightweight Buyer-Seller Watermarking Protocol, Yongdong Wu, Hwee Hwa Pang

Research Collection School Of Computing and Information Systems

The buyer-seller watermarking protocol enables a seller to successfully identify a traitor from a pirated copy, while preventing the seller from framing an innocent buyer. Based on finite field theory and the homomorphic property of public key cryptosystems such as RSA, several buyer-seller watermarking protocols (N. Memon and P. W. Wong (2001) and C.-L. Lei et al. (2004)) have been proposed previously. However, those protocols require not only large computational power but also substantial network bandwidth. In this paper, we introduce a new buyer-seller protocol that overcomes those weaknesses by managing the watermarks. Compared with the earlier protocols, ours is …


On Profiling Blogs With Representative Entries, Jinfeng Zhuang, Steven C. H. Hoi, Aixin Sun Jul 2008

On Profiling Blogs With Representative Entries, Jinfeng Zhuang, Steven C. H. Hoi, Aixin Sun

Research Collection School Of Computing and Information Systems

With an explosive growth of blogs, information seeking in blogosphere becomes more and more challenging. One example task is to find the most relevant topical blogs against a given query or an existing blog. Such a task requires concise representation of blogs for effective and efficient searching and matching. In this paper, we investigate a new problem of profiling a blog by choosing a set of m most representative entries from the blog, where m is a predefined number that is application-dependent. With the set of selected representative entries, applications on blogs avoid handling hundreds or even thousands of entries …


Estimating Local Optimums In Em Algorithm Over Gaussian Mixture Model, Zhenjie Zhang, Bing Tian Dai, Anthony K.H. Tung Jul 2008

Estimating Local Optimums In Em Algorithm Over Gaussian Mixture Model, Zhenjie Zhang, Bing Tian Dai, Anthony K.H. Tung

Research Collection School Of Computing and Information Systems

EM algorithm is a very popular iteration-based method to estimate the parameters of Gaussian Mixture Model from a large observation set. However, in most cases, EM algorithm is not guaranteed to converge to the global optimum. Instead, it stops at some local optimums, which can be much worse than the global optimum.


Tree-Based Partition Querying: A Methodology For Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou Jul 2008

Tree-Based Partition Querying: A Methodology For Computing Medoids In Large Spatial Datasets, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou

Research Collection School Of Computing and Information Systems

Besides traditional domains (e.g., resource allocation, data mining applications), algorithms for medoid computation and related problems will play an important role in numerous emerging fields, such as location based services and sensor networks. Since the k-medoid problem is NP hard, all existing work deals with approximate solutions on relatively small datasets. This paper aims at efficient methods for very large spatial databases, motivated by: (i) the high and ever increasing availability of spatial data, and (ii) the need for novel query types and improved services. The proposed solutions exploit the intrinsic grouping properties of a data partition index in order …