Scott G. Ainsworth

A durable sensor enabled lifeline support for firefighters

Traditionally, firefighters used to use lifelines (example, ropes) when moving through places on fire under impaired visibility. However, these lifelines have their inherent drawbacks like they sometimes get stuck and limit the operational range. A recent research proposed that firefighters automatically deploy sensor nodes along their paths to establish an ad hoc network that promotes the required level of navigation and communication between firefighters who interact to the system using wearable computing devices. An alternative way to implement such system, is to deploy sensors during building construction or later to build a mission critical network that can be used for emergency purposes. Durability with respect to energy available is one of the primary challenges to the success of such networks. Workforce selection strategies which unevenly consume sensor energy can reduce the lifetime of the network significantly. This work proposes and evaluates a new class of strategies that provides an energy efficient workforce management for mission-critical WSNs (e.g. on-site indoor-navigation support system for slow moving firefighters under impaired visibility). Analytical and simulation results demonstrate that the proposed approach significantly increases network lifetime by evenly consuming sensors energy.

Evaluating sliding and sticky target policies by measuring temporal drift in acyclic walks through a web archive

When a user views an archived page using the archives user interface (UI), the user selects a datetime to view from a list. The archived web page, if available, is then displayed. From this display, the web archive UI attempts to simulate the web browsing experience by smoothly transitioning between archived pages. During this process, the target datetime changes with each link followed; drifting away from the datetime originally selected. When browsing sparsely-archived pages, this nearly-silent drift can be many years in just a few clicks. We conducted 200,000 acyclic walks of archived pages, following up to 50 links per walk, comparing the results of two target datetime policies. The Sliding Target policy allows the target datetime to change as it does in archive UIs such as the Internet Archives Wayback Machine. The Sticky Target policy, represented by the Memento API, keeps the target datetime the same throughout the walk. We found that the Sliding Target policy drift increases with the number of walk steps, number of domains visited, and choice (number of links available). However, the Sticky Target policy controls temporal drift, holding it to less than 30 days on average regardless of walk length or number of domains visited. The Sticky Target policy shows some increase as choice increases, but this may be caused by other factors. We conclude that based on walk length, the Sticky Target policy generally produces at least 30 days less drift than the Sliding Target policy.

Towards maximum longevity of energy limited SANETs

One of the major challenges in wireless sensor networks (WSNs) design lies in the constrained energy available to sensor nodes. Workforce selection strategies which unevenly consume sensor energy can reduce the lifetime of the network significantly. This work proposes and evaluates a new class of strategies that provides an energy efficient workforce management for WSNs. Analytical and simulation results demonstrate that the proposed approach significantly increases network lifetime by evenly consuming sensors power.