William L. McGill’s research while affiliated with University of Maryland, College Park and other places

Corrosion in hull structure of Coast Guard cutters is a primary degradation mode that accounts for a significant portion of depot budgets and the occasional unavailability of ships in general. Corrosion exhibits great variability spatially and temporally. This paper presents, summarizes, and analyzes a one-of-a-kind data set for end-of-life corrosion estimation and profile of ship hull structure. The data set was created over several years and on several vessels, and collected by maintenance personnel at several geographic locations. This study analyzes wastage data due to corrosion that were systematically collected in 2007 to 2008 from twelve 210-foot Medium Endurance Cutters, commissioned in 1964 to 1969, in the form of thickness measurement using visual inspection and ultrasonic testing methods. A total of 76,091 thickness measurements were analyzed at positions covering the entire hulls. The measured corrosion levels mean is about 0.02 to 0.04 inches (1 in. = 25.4 mm), i.e., 6 to 14% of the as-built thicknesses after no more than 43 years of use of these 12 cutters as of 2007; however, the analysis of outliers indicates that the average wastage values can be misleading in predicting extreme corrosion. A method is proposed for estimating the counts and intensity of outliers. Examining geographic locations of the operations of these cutters and corrosion revealed that southern warm water led to appreciably larger corrosion compared to the northern colder waters, at a ratio of about 1.25 to 1.5.

The mental models approach, a leading strategy to develop risk communications, involves a time- and labor-intensive interview process and a lengthy questionnaire to elicit group-level risk perceptions. We propose that a similarity ratings approach for structural knowledge elicitation can be adopted to assist the risk mental models approach. The LinkIT game, inspired by games with a purpose (GWAP) technology, is a ludic elicitation tool designed to elicit group understanding of the relations between risk factors in a more enjoyable and productive manner when compared to traditional approaches. That is, consistent with the idea of ludic elicitation, LinkIT was designed to make the elicitation process fun and enjoyable in the hopes of increasing participation and data quality in risk studies. Like the mental models approach, the group mental model obtained via the LinkIT game can hence be generated and represented in a form of influence diagrams. In order to examine the external validity of LinkIT, we conducted a study to compare its performance with respect to a more conventional questionnaire-driven approach. Data analysis results conclude that the two group mental models elicited from the two approaches are similar to an extent. Yet, LinkIT was more productive and enjoyable than the questionnaire. However, participants commented that the current game has some usability concerns. This presentation summarizes the design and evaluation of the LinkIT game and suggests areas for future work.

Recent increases in the number of terrorist bombings and explosions have led to increased need for postblast investigators. Numerous advances have been made in the area of chemical analysis of explosive residues, but little work has been done to aid postblast investigators in the determination of explosive charge weight using postblast structural damage. This technical note discusses the results of a review of existing blast analysis software packages for their ability to be used as a forensic tool supporting postblast investigations. The recurring limitations of the software found in this review are discussed. It is determined that individually the software packages do not show much promise as such a tool, but that when used concurrently, they may have some value to the postblast investigator. However limited knowledge about the built-in safety factors as well as the ability to specify and modify boundary conditions in the software packages have left the authors to pursue other avenues.

One of the main goals of all online social communities is to promote a stable, or perhaps, growing membership built around topics of like interest. Yet, communities are not impermeable to the potentially damaging effects resulting from those few participants that choose to behave in a manner that is counter to established norms of behavior. Typical moderators in online social communities are the ones tasked to reduce the risks associated with unhealthy user behavior by rapidly identifying and removing damaging posts and consequently taking action against the perpetrating user. Yet, the sheer volume of posts relative to the number of moderators available for review suggests a need for modern tools aimed at prioritizing posts based on the assessed risk each user poses to the community. To accomplish this, we propose a threat analysis model. Our model, referred to as TrICO (Threat requires Intent Capability and Opportunity) is implemented using Bayesian Networks, and achieves early detection of damaging behavior in online social communities. To the best of our knowledge, this is the first user-centered model for usage policy enforcement in online sites. We apply our model to a comprehensive data set characterizing the entirety of a popular discussion forum. Our results show that the TrICO model provides accurate results.

This paper introduces the concept of participatory risk management (PRM), the outsourcing of parts of the risk management process to a wide audience of participants, whether from communities affected by risk or netizens willing to lend a helping (analytic) hand. PRM consists of six parts that closely follows the ISO31000 risk management framework: tasking and requirements, participatory risk identification, participatory risk analysis, participatory risk evaluation, participatory risk mitigation and communication. Each phase leverages one or more modern crowdsourcing concepts, such as participatory sensing, human computation, and games with a purpose. A potential PRM gaming system for incentivising community risk management through rewarding play is presented as an example application of PRM.

Despite their limitations as a platform for calculations, Microsoft Excel spreadsheets enjoy widespread use throughout much of engineering and science, and they have emerged as a lingua franca for computations in some quarters. Given their ubiquity, it would be useful if Excel spreadsheets could express uncertainty in inputs and propagate uncertainty through calculations. We describe an add-in for Microsoft Excel that supports arithmetic on uncertain numbers, which include intervals, probability distributions, and p-boxes (i.e., bounds on probability distributions). The software enables native calculations in Excel with these objects and ordinary scalar (real) numbers. The add-in supports basic arithmetic operations (+, –, x, ÷, ˆ, min, max), standard mathematical functions (exp, sqrt, atan, etc.), and Excel-style cell referencing for both function arguments and uncertain number results. Graphical depictions of uncertain numbers are created automatically. Using function overloading, the standard Excel syntax is extended for uncertain numbers so that the software conducts uncertainty analyses almost automatically and does not require users to learn entirely new conventions or special-purpose techniques.

A review of existing literature dealing with the behavior of often-used building materials subject to blast loading is presented. Our focus is on the types of structural damage that might be observed at a blast scene, and in particular how this evidence can be used to infer characteristics of the blast (e.g., size and position of the charge). We consider two simple questions: what does damage look like in the wake of a blast for different structural materials (i.e., “what damage is seen?”) and what must the blast pressure have been to cause this damage (i.e., “what does the damage mean?”). This review looks at reinforced concrete, masonry, steel, glass, and timber. We propose the following principle for interpreting observed damage at a blast scene: if damage is present, a limit state was exceeded. The results from this review will be of great interest to post-blast investigators that seek to understand the size and position of a blast.

We describe a scientific casual browser game called LinkIT for eliciting societal risk perceptions in the form of mental models represented as influence diagrams. Given this knowledge, we can highlight similarities and differences across demographic groups as well as compare individual responses with expert models. These comparisons inform how risk should be best communicated to resolve knowledge gaps and misperceptions. Here we introduce the LinkIT concept, present preliminary results and propose future work.

This paper introduces the concept of participatory risk management (PRM). By involving community members and netizens in the risk management process we believe the community will become safer and participants will become smarter in dealing with risks. A PRM gaming system concept for incentivizing community risk management through rewarding play is presented as an example application of PRM.