Motivated by applications in health care systems, this study focused on queueing network models with instances of simultaneous resource possession under capacity restrictions in different stages. Customers during service at certain nodes in the first-level or primary system may simultaneously need service from a second-level server. In this…

The objective of this study was to develop a "Virtual Design Studio (VDS)": a software platform for integrated, coordinated and optimized design of green building systems with low energy consumption, high indoor environmental quality (IEQ), and high level of sustainability. The VDS is intended to assist collaborating architects,…

Software architecture plays an increasingly important role in complex software development. Its further application, however, is challenged by the fact that software architecture, over time, is often found not conformant to its implementation. This is usually caused by frequent development changes made to both artifacts. Against this background,…

With increasing demand of mobile devices and cloud computing, it becomes increasingly important to develop efficient mobile application and its secured backend, such as web applications and virtualization environment. This dissertation reports a systematic study of mobile application development and the security issues of its related backend. …

Organizations continue to rely on password-based authentication methods to control access to many Web-based systems. This research study developed a benchmarking instrument intended to assess authentication methods used in Web-based information systems (IS). It developed an Authentication Method System Index (AMSI) to analyze collected data from…

Wayfinding is a kind of spatial riddle that people encounter almost daily. Although it has been well documented that wayfinding elements--namely, environmental cues, people and time--significantly influence wayfinding, there has been little work done to examine the effectiveness of those influences. In particular, the notion of wayfindingly…

The increasing proliferation of globally interconnected complex information systems has elevated the magnitude of attacks and the level of damage that they inflict on such systems. This open environment of intertwined financial, medical, defense, and other systems has attracted hackers to increase their malicious activities to cause harm or to…

Location-based services (LBS for short) providers require users' current locations to answer their location-based queries, e.g., range and nearest-neighbor queries. Revealing personal location information to potentially untrusted service providers could create privacy risks for users. To this end, our objective is to design a privacy-preserving…

In spite of the goodwill and best efforts of software engineers and usability professionals, systems continue to be built and released with glaring usability flaws that are costly and difficult to fix after the system has been built. Although user interface (UI) designers, be they usability or design experts, communicate usability requirements to…

The enterprise software market is seeing the rise of a new business model--selling Software-as-a-Service (SaaS), in which a standard piece of software is owned and managed remotely by the vendor and delivered as a service over the Internet. Despite the hype, questions remain regarding the rise of this new service model and how it would impact the…

This dissertation focuses on the collaboration of multiple heterogeneous, intelligent agents (hardware or software) which collaborate to learn a task and are capable of sharing knowledge. The concept of collaborative learning in multi-agent and multi-robot systems is largely under studied, and represents an area where further research is needed to…

Many people in general think that digital game environment has potential as a learning environment. However, empirical research in digital game environment and education is a still relative young field, so to create a digital learning environment where students are actively engaged in the learning process is a great challenge. In part, it has been…