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Empirical Decision Rules for Improving the Uncertainty Reporting of Small Sample System Usability Scale Scores
No full textThe System Usability Scale (SUS) is a short, survey-based approach used to determine the usability of a system from an end-user perspective once a prototype is available for assessment. Individual scores are gathered using a ten-question survey with the survey results reported in terms of central tendency (sample mean) as an estimate of the system’s usability (the SUS study score), and confidence intervals (CIs) on the sample mean are used to communicate uncertainty levels associated with this point estimate. When the number of individuals surveyed is large, the SUS study scores and accompanying confidence intervals relying upon the central limit theorem for support are appropriate. However, when only a small number of users are surveyed, reliance on the central limit theorem falls short, resulting in CIs that suffer from parameter bound violations and interval widths that confound mappings to adjective and other constructed scales. These shortcomings are especially pronounced when the underlying SUS score data is skewed, as it is in many instances. This paper introduces an empirically based remedy for such small-sample circumstances, proposing a set of decision rules that leverage either an extended bias-corrected accelerated (BCa) bootstrap confidence interval (Cl) or an empirical Bayesian credibility interval about the sample mean to restore and bolster subsequent Cl accuracy. Data from historical SUS assessments are used to highlight shortfalls in current practices and to demonstrate the improvements these alternate approaches offer while remaining statistically defensible. A freely available, online application is introduced and discussed that automates SUS analysis under these decision rules, thereby assisting usability practitioners in adopting the advocated approaches
Stimulating Student Preparation in Introductory Engineering Mechanics
No full textEngineering mechanics is the foundation for an engineering curriculum. It is crucial to comprehend and retain this knowledge to be successful in advanced courses such as structural analysis and machine component design, as well as to pass the fundamentals of engineering (FE) exam. The study presented in this paper details the approach taken to replace in-class quizzes with regular out-of-class homework assignments in an introductory engineering mechanics course. The objectives of the study were to: 1) provide students with a variety of problems to apply both new and previous knowledge; 2) encourage engagement with the course material outside of in-person lessons; and 3) teach students to reflect and self-assess their own learning. Eighteen homework assignments were added throughout the thirty-lesson course. Each assignment consisted of two parts; practice problems from previous lessons and conceptual responses based on preparation for the next lesson. At the beginning of each class, students were given the opportunity to assess their own work and clarify any points of confusion. Instructors also provided focused, frequent, and timely digital feedback on these assessments. Instructors graded each assignment based on a holistic evaluation of the students’ comprehension in four domains: 1) approach to problem solving, 2) demonstration of engineering concepts, 3) application of fundamental math concepts, and 4) accuracy and presentation of the final answer. The effectiveness of the assignments was evaluated based on time students engaged with the material outside of class, historical performance on mid-term and final examinations, and student and instructor feedback. The results of the study showed frequent out-of-class assessments allowed students to spend a consistent amount of time with the course material per lesson and reduced the reported study time for midterm and final examinations. Students’ time spent preparing for each lesson increased by 22%, but time spent preparing for examinations decreased by 29%. Student feedback showed regular assessments were a useful tool when preparing for examinations and assisted in learning the material. However, the students’ performance on historical examinations showed negligible impact on comprehension of course topics. Further research is required to evaluate long-term retention
Will It Work? Examining Alignment of Four Infrastructure Solutions with the Draft ASCE 73 Standard Requirements for Sustainable Infrastructure
No full textThis study examines ASCE’s draft sustainable infrastructure standard—ASCE/COS 73 Standard Requirements for Sustainable Infrastructure—to assess its alignment with current construction and design practices. A team of students and faculty from the United States Military Academy applied the draft document to four current and planned infrastructure projects. The scope of the study included an analysis of a university dormitory, a mass-timber residential skyrise, a ferry port expansion, and a multi-purpose mass-transport project. The objective was to assess alignment of the draft standard with current construction and design practices, not to assess or rate the projects themselves. The research team generated questions and gathered information from project owners and key leaders through surveys, interviews, and shared files. Both quantifiable and non-quantifiable measures were used to assess alignment with the sustainable infrastructure outcomes presented in the draft standard. The results indicate the draft standard challenges infrastructure development toward needed sustainability practices, while still being achievable within the current state of design and practice in the construction industry. Additionally, the study identifies recommendations for future studies using ASCE/COS 73
State Estimation of a Partially Observable Multi-Link System with No Joint Encoders Incorporating External Dead-Reckoning
No full textThis paper presents a technique for state estimation of a multi-link system having no joint encoders, which can only be partially observed by a camera. To fully observe the system without changing the current configuration, a gyroscope and an accelerometer are attached to each link as dead-reckoning sensors. Observations of the dead-reckoning sensors are associated with the states of the multi-link system such that the states are fully observable. The camera, which observes part of the system globally, is used as a global corrector in the framework of an extended Kalman filter to filter the dead-reckoning errors accumulated over time. Parametric studies in simulation have investigated and identified the efficacy of the proposed technique in estimating the state of the multilink system. Experimental validation using a two-link arm has demonstrated the applicability of the proposed technique to real-world multi-link systems
Using Spatial Uncertainty to Dynamically Determine UAS Flight Paths
No full textIn the aftermath of radiation or chemical accidents, responders must rapidly map out regions of contamination as quickly and accurately as possible. One important and relevant statistical method for this kind of disaster response is spatial kriging, which makes predictions based on incomplete knowledge of spatially referenced observations. Given an Unmanned Aerial System (UAS) equipped with radiation sensors, we develop a spatial statistics-based approach to optimally map out a contamination field over a geographic region. In this article, we evaluate three approaches to UAS mapping: a Variance Driven Sampling (VDS) approach that minimizes kriging variance, a more computationally intensive Hybrid Entropy Search (HES), and a baseline Levy Flight search. Considering limited UAS range, we also implement a restricted version of these approaches that only considers nearby points. We find that HES is optimal for small numbers of sampled points with the restricted versions of HES and VDS becoming optimal for larger samples. Ultimately, the best method is dependent on the number of samples to be taken, with each method providing clear benefits over a random search in terms of both mean squared error and path length. We demonstrate the advantages of our methodology using actual radiation field test data from the Idaho National Lab
Predicting Individual Differences to Cyber Attacks: Knowledge, Arousal, Emotional and Trust Responses
No full textCyber attacks are increasingly commonplace and cause significant disruption, and therefore, have been a focus of much research. The objective of this research was to understand the factors that might lead users to fail to recognize red flags and succumb to cyber events. We investigated users’ knowledge of cyber attacks, their propensity to trust technology, arousal, emotional valence, and situational trust in response to different types and severity of cyber attacks. Our findings suggest that high-risk attacks elicited more arousal and more negative emotional valence than low-risk attacks. The attack-type manipulation revealed that phishing scenarios yielded distinctive patterns, including weaker affective responses than ransomware and other malware. The authors further examined arousal, emotional valence, and situational trust patterns among the subset of high- knowledge participants who successfully identified all the attacks and compared these responses with those of less knowledgeable peers. Our findings suggest that the more knowledgeable the user, the higher was their general propensity to trust technology, the more sensitive were their emotional responses to the manipulation of risk, and the lower their situational trust when faced with cyber attack scenarios
Enhancing the foreign language classroom through experiential learning: Connecting and reflecting
Get PDFThis paper highlights examples of the various ways students in beginner Russian, intermediate Spanish and advanced French engage with the local and regional community in educational and noneducational settings. It explains the history of these engagements and provides instructor impressions as well as impressions from student participants and community partners concerning learning outcomes and the benefits to both students and the community. In all three examples, the majority of students were taking the course to fulfill a core requirement. The number of students who participated in each experiential learning initiative varied from as few as ten to as many as 120 at a given time.https://digitalcommons.usmalibrary.org/books/1063/thumbnail.jp
Constitutive Modeling and Validation of Sintered Metal Powders Subjected to Large Strains and High Strain Rates
No full textThe development of advanced small caliber weapon systems has resulted in rounds with more material penetration capabilities. The increased capabilities may mean that existing live-fire facilities will no longer be adequate for the training and certification of military and law enforcement personnel, which could result in training constraints and possibly expensive upgrades to improve the safety of existing facilities. New training ammunition manufactured from novel structural materials are needed to allow for the safe, continued use of live-fire shoot house facilities. The goal of this project is to characterize a sintered metal powder and fit a suitable constitutive model for simulation in support of numerical design. A pressed and sintered blend of copper-tin was selected as a suitable representative material for this application. Samples were tested in uniaxial compression under quasi-static conditions and elevated temperatures. Dynamic compression testing at strain rates up to approximately 105 s-1 was conducted using a split-Hopkinson bar. The results of these tests were then used to fit Johnson-Cook and Zerilli-Armstrong strength models to the test data. The models were fit by selecting points from test data at different strain rates and elevated temperatures. This system of equations was then solved for each model while using the same test data to ensure a fair comparison of the results. A Mie-Gruneisen equation of state for the material was estimated using a rule of mixtures and existing shock and particle velocity data. Taylor cylinder tests were conducted and the rate of change in length was measured using high-speed video. Simulation of the Taylor tests was conducted using the developed strength and equation of state model and compared to the experimental results for model validation and comparison. Both the Johnson-Cook and Zerilli-Armstrong models resulted in less than 1% error of the Taylor cylinder results before material fracture. Further development of a fracture model for this material is recommended for use in high strain rate modeling applications
