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Effect of armrest positioning and workspace constraints on muscle activity for touchless gestural controls
No full textThe recent development of affordable technologies now allow touchless gestural controls to be integrated in common computing environments, however, ergonomic issues (user fatigue, in particular) have not been solved. This experiment investigates shoulder muscle activity for different traditional supported or user-preferred touchless gesture interaction scenarios and quantifies the location that touchless gestural control users would like to position armrests in different gestural workspaces. A custom hand/finger-based gestural control system was developed using a motion tracking system. Users browed an online shopping website while a prototype office chair allowed them to positon armrests easily in a wide space in front of themselves. Results show that median muscle activity of the upper trapezius, medial deltoid, and anterior deltoid are significantly affected by armrest configuration. User-preferred armrest positions generally reduced muscle activity compared to traditional positions, but this reduction was greatest when the gesture space is constrained over the desktop. In those conditions, average user preferred positioning of the armrest was higher and closer to the sternum of the user
Single Capillary Electrospinning of Magnetic Core-shell Nanofibers
No full textVarious hierarchical structures (e. g. hollow, core‐shell, etc.,) have been synthesized by coaxial or multi‐fluidic compound‐jet electrospinning. However, the setup is complex and the parameters need to be carefully controlled. Herein, we report the creation of CoAl0.1Fe1.9O4 (CAF) solid, core‐shell, and hollow nanofibers via a single capillary electrospinning in combination with a controllable pre‐drying process of precursor nanofibers. The formation mechanism were outlined by investigating their morphology and microstructure in response to different experimental conditions. Moreover, these CAF core‐shell nanofibers were demonstrated the highest HC as compared to their solid and hollow nanofibers due to the enhanced magnetic surface anisotropy. The present single capillary electrospinning is not only a universal and effective method, but also can be readily extended to fabricate other materials with multi‐hollow structure
Taking Experiential Learning Online in an Acoustics Elective Course
No full textStarting in 2007, this survey course has been part of an acoustics minor. Originally envisioned to capture foundational concepts of acoustics that would be essential to a wide variety of engineering and scientific applications, this course is aimed at a junior/senior level audience to reflect the initiative and maturity required of the student. Topics emphasize the interdisciplinary nature of acoustics in industry, incorporating digital signal processing, psychoacoustics, and applications in room acoustics and environmental noise. Its evolution from a face-to-face studio environment to a hybrid and then fully online course has retained a hands-on experiential course design. Themes of art and design have been essential to its success. Challenges arose in teaching the course online, and solutions to promote learner engagement and consistency are described
Effect of control-display transfer function on pointing performance for a hand/finger based touchless gestural controls
No full textRecent technologies now allow touchless gestural controls to be integrated as computing input devices. Unlike traditional input devices, the effect of design parameters (such as control-display transfer functions for physical to onscreen movements) for touchless controls is largely unknown. This paper presents an experiment where a hand- and finger-based touchless gestural control system replaced typical pointing and clicking functions of a mouse. The effect of different pointer-acceleration-based control-display transfer functions (dynamic CD gain with different scaling factors) on performance for a standard, 2-dimensional Fitts’ task was evaluated for 15 participants. Additionally, the influence of armrest support positioning was investigated. Results showed significantly increased error rates for the high level of control-display gain (SF=1000) in the gestural controls. Neither CD gain nor armrest position had significant effect on effective throughput or movement times, though lower CD gain showed the best performance and lowest error rates. Overall performance for the touchless gestural system was less than that of a traditional mouse, though comparable to previous gestural or remote pointing systems
Energy-aware Economic Production Quantity model with variable energy pricing
No full textIn this paper, an energy-aware Economic Production Quantity (EPQ) model is presented to determine optimum production run length and batch size with respect to variable energy cost. Here, variable unit production cost includes energy consumption charge which is a function of production time and time-of-use, and alternates between two prices during peak and off-peak hours. This paper addresses the above integration in order to minimize the overall cost of the system. In the first phase of this study, a new scenario-based framework is proposed to find the optimal value of production time. In the second phase, a general mixed integer nonlinear programming (MINLP) model is developed for the given framework. The energy cost defined by the framework and mathematical model depends on the number of peak periods during the production period and is calculated using floor functions. The MINLP is solved numerically and analytically, and a closed form solution is obtained for the production run length. The model is analyzed for different scenarios and the results are discussed