Nowadays people and organizations are more and more interconnected in the forms of social networks: the nodes are social entities and the links are various relationships among them. The social network theory and the methods of social network analysis (SNA) are being increasingly used to study such real-world networks in order to support knowledge management and decision making in organizations. However, most existing social network studies focus on the static topologies of networks. The dynamic network link formation process is largely ignored. This dissertation is devoted to study such dynamic network formation process to support knowledge management and decision making in networked environments. Three challenges remain to be addressed in modeling and analyzing the dynamic network link formation processes. The first challenge is about modeling the network topological changes using longitudinal network data. The second challenge is concerned with examining factors that influence formation of links among individuals in networks. The third challenge is regarding link prediction in evolving social networks. This dissertation presents four essays that address these challenges in various knowledge management domains. The first essay studies the topological changes of a major international terrorist network over a 14-year period. In addition, this paper used a simulation approach to examine this network's vulnerability to random failures, targeted attacks, and real world authorities' counterattacks. The second essay and third essay focuses on examining determinants that significantly influence the link formation processes in social networks. The second essay found that mutual acquaintance and vehicle affiliations facilitate future co-offending link formation in a real-world criminal network. The third essay found that homophily in programming language preference, and mutual are determinants for forming participation links in an online Open Source social network. The fourth essay focuses on the link prediction in evolving social networks. It proposes a novel infrastructure for describing and utilizing the discovered determinants of link formation process (i.e. semantics of social networks) in link prediction to support expert recommendation application in an Open Source developer community. It is found that the integrated mechanism outperforms either user-based or Top-N most recognized mechanism.

Community-based open source (community source) has emerged as a new approach of developing enterprise software systems that requires participation and investments from partner institutions. This new approach provides the opportunity for institutions to pool resources together to achieve objectives that are hard to reach individually. In my dissertation, community-based development of enterprise applications is examined in a real world project called Kuali through the following three perspectives: technology perspective, economic perspective and management perspective. Under the technology perspective, the main research question is "how do service-oriented architectures enable technology flexibility in community source?" The Kuali case provides the initial context for understanding the basic concepts and insights surrounding the technological issues in community source. Under the economic perspective, the main research question is "why are institutions interested in investing in community source?" The case study and analytical modeling are used to better understand the decision-making process in community source. Under the management perspective, two main research questions are studied. The first research question is "what are the factors affecting the project success in community source development?" The case study, the surveys and the interviews are conducted to test the community source project success model. The second research question is "what are the motivations for outsourcing software development in community source?" Based on the results of our interview analysis, we propose a research framework for community source outsourcing. In the long term, I would like to develop a generic framework for describing the process of acquiring application software via either commercial, open source, or home grown approach. My research will concentrate on comparing these three application development approaches with a special focus on community source. The main contribution of my dissertation is to provide guideline for strategic planning and decision making in an institution. The finding in this dissertation research will provide significant insights on the selection of various software development approaches that are useful for both researchers and practitioners.

Open-source software becomes increasingly popular nowadays. Many startup companies and small business owners choose to adopt open source software packages to meet their daily office computing needs or to build their IT infrastructure. Unlike proprietary software systems, open source software systems usually have a loosely-organized developer collaboration structure. Developers work on their "assignments" on a voluntary basis. Many developers do not physically meet their "co-workers." This unique developer collaboration pattern leads to unique software development process, and hence unique structure of software products. It is those unique characteristics of open source software that motivate this dissertation study. Our research follows the framework of the four key elements of software engineering: Project, People, Process and Product (Jacobson, Booch et al. 1999). This dissertation studies three of the four P's: People, Process and Product. Due to the large sizes and high complexities of many open source software packages, the traditional analysis methods and measures in software engineering can not be readily leveraged to analyze those software packages. In this dissertation, we adopt complex network theory to perform our analysis on open source software packages, software development process, and the collaboration among software developers. We intend to discover some common characteristics that are shared by different open source software packages, and provide a possible explanation of the development process of those software products. Specifically we represent real world entities, such as open source software source code or developer collaborations, with networks composed of inter-connected vertices. We then leverage the topological metrics that have been established in complex network theory to analyze those networks. We also propose our own random network growth model to illustrate open source software development processes. Our research results can be potentially used by software practitioners who are interested to develop high quality software products and reduce the risks in the development process. Chapter 1 is an introduction of the dissertation's structure and research scope. We aim at studying open source software with complex networks. The details of the 4-P framework will be introduced in that chapter. Chapter 2 analyzes five C-language based open source software packages by leveraging function dependency networks. That chapter calculates the topological measures of the dependency networks extracted from software source code. Chapter 3 analyzes the collaborative relationship among open source software developers. We extract developer's co-working data out of two software bug fixing data sets. Again by leveraging complex network theory, we find out a number of topological characteristics of the software developer networks, such as the scale-free property. We also realize the topological differences between from the bug side and from the developer side for the extracted bipartite networks. Chapter 4 is to compare two widely adopted clustering coefficient definitions, the one proposed by Watts and Strogatz, the other by Newman. The analytical similarities and differences between the two clustering coefficient definitions provide useful guidance to the proposal of the random network growth model that is presented in the next chapter. Chapter 5 aims to characterize the open source software development process. We propose a two-phase network growth model to illustrate the software development process. Our model describes how different software source code units interconnect as the size of the software grows. A case study was performed by using the same five open source software packages that have been adopted in Chapter 2. The empirical results demonstrate that our model provides a possible explanation on the process of how open source software products are developed. Chapter 6 concludes the dissertation and highlights the possible future research directions.

To increase productivity, application developers are using tools that allow them to create higher quality applications faster. One such set of tools, open-source frameworks, allows application developers to reuse software artifacts and should increase application quality. However, given the vast number of open-source frameworks available, users must be able to differentiate among frameworks and select the one best suited for them. In this study, we expand the taxonomy of open-source frameworks and analyze the impact of the framework's characteristics, technical quality, and social pressure on perceived usefulness and continued framework usage intention. Our findings suggest that understandability and flexibility have a significant impact on perceived ease of use, while perceived usefulness is mainly determined by flexibility and efficiency. Our research can be used to understand what influences developers to continue using frameworks and to improve framework development. / viii, 129 leaves : ill. ; 29 cm

Visualization of digital geographic data is often accomplished through custom symbology that is saved in a proprietary format called a layer file (.lyr). The sharing of free geographical information system (GIS) data can be limited as the symbology data is bound inthe .lyr file format. This makes it harder and more tedious to work with open software tools since it is not possible to convert or open the .lyr file in free and open GIS software and thus limits the distribution of free GIS data. The aim of this thesis is to increase the interoperability of .lyr data between proprietary and free and open GIS software. This was done by revers eengineering the .lyr file format to document the file structure and to distribute the knowledge and metadata gained from this project to the open source community. Reverse engineering the.lyr format provided a well needed metadata and documentation about the format which increases the interoperability and enable future work to continue to lessen the gap between open source and commercial software. This groundwork can therefore, enable a continued development of data interoperability between proprietary and free and open GIS software.

Package party, implemented in the R system for statistical computing, provides basic classes and methods for recursive partitioning along with reference implementations for three recently-suggested tree-based learners: conditional inference trees and forests, and model-based recursive partitioning. / Series: Research Report Series / Department of Statistics and Mathematics

This study tests a theoretical model developed to investigate the impact of assimilation of commercial open source enterprise resource planning software (COSES) in small and medium sized enterprises (SMEs). Specifically, the model explains how the top management team’s (TMT’s) information technology (IT) knowledge and experience impact both assimilation and firm performance. The hypotheses were tested using survey data from SMEs that have implemented COSES. Results from structural equation modeling suggest that SMEs benefit, through higher levels of assimilation and performance, from adopting innovative enterprise resource planning (ERP) systems such as COSES when they have a TMT that has experience with and is knowledgeable about technology. The study also highlights the importance of the TMT in facilitating IT assimilation.

Open source software (OSS) is typically created in a decentralized self-organizing process by a community of developers having the same or similar interests. A key factor for the success of OSS over the last two decades is the internet: Developers who rarely meet face-to-face can employ new means of communication, both for rapidly writing and deploying software. Therefore, many tools emerged that assist a collaborative software development process, including in particular tools for source code management (SCM) and version control. In the R world, SCM is not a new idea, in fact, the R Development Core Team has always been using SCM tools for the R sources; first by means of Concurrent Versions System (CVS), and then via Subversion (SVN). A central repository is hosted by ETH Zürich mainly for managing the development of the base R system. Mailing lists like R-help, R-devel and many others are currently the main communication channels in the R community. Also beyond the base system, many R contributors employ SCM tools for managing their R packages, e.g., via web-based SVN repositories like SourceForge (http://SourceForge.net/) or Google Code (http://Code.Google.com/). However, there has been no central SCM repository providing services suited to the specific needs of R package developers. Since early 2007, the R-project offers such a central platform to the R community. R-Forge (http://R-Forge.R-project.org/) provides a set of tools for source code management and various web-based features. It aims to provide a platform for collaborative development of R packages, R-related software or further projects. / Series: Research Report Series / Department of Statistics and Mathematics

In this study, the researcher created a model and software application for identifying the factors that are relevant in the decision making process to select and implement Open-source applications in higher education. Open-source applications provide the programming syntax to the user for customization. Unlike proprietary software, where the source code is unavailable and illegal to alter, an Open-Source Software (OSS) application authorizes the user to edit and recompile the application to meet the specific needs of the institution or organization. OSS applications are either free or purchasable for a one-time fee. The rising cost of proprietary software has motivated many academic institutions to consider implementing OSS. Many IT professionals are investigating the advantages and disadvantages of open-source applications in an attempt to mitigate expensive yearly fees, licensures and maintenance costs required by proprietary software vendors. The data collected in the study represented OSS and non-OSS enabled institutions that were members of the Council of Higher Education and Accreditation (CHEA) Organization. Of the data collected from the institutions, a portion of the information was set aside for validation purposes. The model created in this research addressed the OSS concerns in higher education by identifying the experiences, institutional characteristics, and technical systems relevant to the selection and implementation of OSS applications. The researcher used the Visual Basic .NET programming language to create the model and software application that provided academic institutions with technical OSS information and support. The Intelligent Software Agent (ISA) simplified the data analysis process by providing a Graphical User Interface (GUI) for the user to enter and receive data. The results of this research allowed institutions to specify certain criteria such as highest degree awarded, relevant characteristics, and technological factors and then receive implementation suggestions for adopting OSS applications. The validation process indicated that the tabled data in the model and generated suggestions of the ISA were statistically comparable with the data that was set-aside for validation purposes.

Project PANOPTES (http://www.projectranoptes.org) is aimed at establishing a collaboration between professional astronomers, citizen scientists and schools to discover a large number of exoplanets with the transit technique. We have developed digital camera based imaging units to cover large parts of the sky and look for exoplanet transits. Each unit costs approximately $5000 USD and runs automatically every night. By using low-cost, commercial digital single-lens reflex (DSLR) cameras, we have developed a uniquely cost-efficient system for wide field astronomical imaging, offering approximately two orders of magnitude better etendue per unit of cost than professional wide-field surveys. Both science and outreach, our vision is to have thousands of these units built by schools and citizen scientists gathering data, making this project the most productive exoplanet discovery machine in the world.