Tech Briefs

Effect of Acceleration Frequency on Spatial Orientation Mechanisms

Extreme motion environments can induce loss of visual acuity, motion sickness, and spatial disorientation. Understanding how human sensory integration of acceleration stimuli affects spatial awareness will improve models of spatial disorientation and mishap analysis. While there are numerous studies describing vestibular semicircular canal responses to angular acceleration, less is known about vestibular otolith responses to linear acceleration. This gap in knowledge is important to resolve, since seasickness and airsickness are highly dependent on the predominant frequency of a linear acceleration stimulus.

Posted in: Briefs, Medical, Body regions, Human factors, Nervous system, Vehicle acceleration, Vehicle dynamics
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Localization of Head-Mounted Vibrotactile Transducers

T he human sensory systems most frequently used in military displays (vision and audition) are sometimes overloaded. When soldiers rely on visual or auditory displays, their situation awareness can be degraded due to the need to attend to the display. A proposed alternative sensory channel for soldier displays is the tactile channel. In military applications, VT displays are primarily being used to aid in orientation, navigation, and communication. Tactile displays can also be used to impart more abstract information such as in command-and-control applications.

Posted in: Briefs, Physical Sciences, Displays, Vibration, Helmets, Military vehicles and equipment
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High-Resolution, Measurement-Based, Phase-Resolved Prediction of Ocean Wavefields

Given remote and direct physical measurements of a realistic ocean wavefield, the goal of this work was to obtain a high-resolution description of the wavefield by integrating the measurements with phase-resolved wave prediction models including realistic environmental effects such as wind forcing and wave breaking dissipation. The measurements necessary for achieving this reconstruction were guided, and the validity, accuracy, and limitations of such wavefield reconstructions were addressed.

Posted in: Briefs, Physical Sciences, Measurements, Simulation and modeling, Water
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Measuring Impact Damage to Toughened CFRP Laminates with Time Domain Reflectometry

Laminated Carbon Fiber Reinforced Polymer (CFRP) composites are very effective in weight saving in aeronautical structural components. For these laminated CFRP structures, it is difficult to detect damage such as delamination, matrix cracks, and local fiber breakages caused by low-velocity impact loading because these damages are difficult to detect from the outside of the structure. This difficulty of inspection of the laminated CFRP structures demands the development of automatic monitoring or damage detection systems.

Posted in: Briefs, Physical Sciences, Measurements, Composite materials, Lightweight materials
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Testing Mechanical Properties of Polymer-Based Multi- Phase Particulate Composites

Polymer composites comprised of metallic particles distributed throughout a contiguous polymer matrix can often be modified to produce advanced composites that exhibit multifunctional characteristics. The properties of the particulate composites often depend on varying particle size, loading fractions, particle type, and the adhesion between the particulate and the matrix. Studies have shown that particle size, shape, and concentration, and properties of the constituents can affect mechanical properties. This work compared aluminum and nickel particles in PMMA thermoplastic prepared by injection molding, with the same particles in epoxy prepared in a cast-cure process.

Posted in: Briefs, Physical Sciences, Composite materials, Test procedures
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Humanlike Articulated Robotic Headform for Respirator Fit Testing

The testing of individual respiratory protection (IRP) devices is now accomplished with panels of human wearers. Historical at tempts to simulate the human face and head have been unsuccessful for a variety of reasons that include imprecision in reproduction of facial dimensions and unrepresentative textures of the surfaces applied to headforms.

Posted in: Briefs, Physical Sciences, Human factors, Medical equipment and supplies, Robotics
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Three-Dimensional Plastic Part Extrusion and Conductive Ink Printing for Flexible Electronics

Structural electronics, or structronics, seeks to build wiring and electrical interconnects directly into component structures to diminish the need for structural fasteners. A MakerBot Cupcake Computer Numerical Control (CNC) was used to investigate the fabrication of plastic structures by printing, and a Fujifilm Dimatix Materials Printer (DMP) was used to create flexible Printed Circuit Boards (PCBs). After developing processes to make these machines easier to use, others will be able to utilize them to develop structures with integrated electronics.

Posted in: Briefs, Manufacturing & Prototyping, Electronic equipment, Additive manufacturing, Plastics, Parts
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