Quantitative measurement of vertigo frequency: Preliminary results

2003 ◽  
Vol 13 (1) ◽  
pp. 53-56
Author(s):  
Robert Aureo Zalewski-Zaragoza ◽  
Erik Scott Viirre
Keyword(s):  
Quantitative Measurement ◽  
Average Frequency ◽  
Repeated Measurements ◽  
Virtual Image ◽  
Subjective Ratings ◽  
Image System ◽  
Head Mounted Display ◽  
Tinnitus Treatment ◽  
Specific Frequency ◽  
Rehabilitation Exercises

Persons who experience vertigo often describe their symptoms as a sensation of oscillations. Based on such a description, a pilot study was performed to determine if the frequency of the vertigo sensation could be quantified in a manner analogous to tone matching in tinnitus treatment. Fifteen subjects were tested using a virtual image system that consisted of a head mounted display showing a scene that oscillated horizontally or vertically at an adjustable frequency. Subjects were asked to adjust the direction and frequency to match their typical vertigo sensation. Results show that most persons with chronic vertigo had symptoms that could be realistically simulated by vection induced by the oscillating scene and that matched to a consistent specific frequency. They reported an average frequency of 1.09 Hz (range 0.27 to 3.3 Hz, SD 0.25). The large majority (13 out of 15) matched to a horizontal stimulus. Subjects that gave particularly high subjective ratings of the similarity of the motion sensation (7–8 out of 10) from the vection to their vertigo had lower frequency matches (average 0.61 +/- 0.25). Repeated measurements in 4 subjects 8 to 27 days later showed consistent results. This vertigo measurement technique may be used in the future to assess the ability of vestibular rehabilitation to reduce chronic vertigo. Identification of a specific frequency of chronic vertigo may be important in the specification of rehabilitation exercises.

Wearable optical see-through head-mounted display capable of adjusting virtual image depth

2014 ◽  
Vol 12 (6) ◽  
pp. 060011-60013 ◽  
Author(s):  
Chen Xu Chen Xu ◽  
Dewen Cheng Dewen Cheng ◽  
Haichao Peng Haichao Peng ◽  
Weitao Song Weitao Song ◽  
Yongtian Wang Yongtian Wang
Keyword(s):  
Virtual Image ◽  
Head Mounted Display ◽  
Image Depth

Vibration Control of Offshore Platforms Using a Wideband METMD System

2006 ◽  
Author(s):  
Dong Zhao ◽  
Rujian Ma ◽  
Dongmei Cai
Keyword(s):  
Vibration Control ◽  
Natural Frequency ◽  
Fem Simulation ◽  
Average Frequency ◽  
Offshore Platforms ◽  
Frequency Bandwidth ◽  
Wave Load ◽  
Control Effect ◽  
Exciting Frequency ◽  
Specific Frequency

A wideband multiple extended tuned mass dampers (METMD) system has been developed for reducing the multiple resonant responses of the platforms to all kinds of loads, such as earthquake, typhoon, tsunami and big ice load. This system is composed of several subsystems, each of which consists of one set of extended tuned mass damper (ETMD) unit covering a specific frequency bandwidth, and its average frequency is tuned to one of the first resonant frequencies of the platform. The offshore platform is simplified to a single degree-of-freedom (DOF) system to which a METMD subsystem (composed of m ETMDs) is attached and constitutes m+1 DOFs system. The total mass ratio of the METMD subsystem to the platform is 14% and the frequency ratio of the exciting frequency to the platform’s natural frequency varies in [0.5, 1.5]. The theory analysis shows that: 1) the platform has the better vibration control effect when the non-dimensional frequency bandwidth Ω, which is defined as the ratio of the frequency range to the controlled (target) platforms natural frequency, is in [0.35, 0.6]; 2) the damping coefficient ξ of ETMD systems is in [0.05, 0.15] and 3) the number of the ETMDs is 5 when Ω = 0.45 and ξ = 0.1. The FEM simulation shows that the METMD has a better vibration control effect on the mega-platforms’ vibration control under the random ocean wave load.

Quantitative Measurement of Human Visual Characteristic on Depth Perception with Using Random-Dot Stimulus

2000 ◽  
Vol 44 (21) ◽  
pp. 3-500-3-500
Author(s):  
Jing-Long Wu ◽  
Kazuyoshi Tsukamoto
Keyword(s):  
Depth Perception ◽  
Quantitative Measurement ◽  
Binocular Disparity ◽  
Experimental Results ◽  
Depth Information ◽  
Head Mounted Display ◽  
Visual Characteristic

Human interactive characteristic between the binocular disparity and the occlusion for depth perception is measured with using random-dot stimulus. The experimental results suggested that if the binocular disparity is set at a proper value, the depth information is mainly obtained from the cue of the binocular disparity, and if the occlusion ratio is larger than some constant value the depth information is obtained from the cue of the occlusion. Based on the experimental results, we can find a method to make images with depth information in the Head Mounted Display (HMD) when the cues of the binocular disparity and the occlusion are concurrently used.

scholarly journals Comparison of spatial orientation skill between real and virtual environment

2021 ◽  
Author(s):  
S. Pastel ◽  
D. Bürger ◽  
C. H. Chen ◽  
K. Petri ◽  
K. Witte
Keyword(s):  
Virtual Environment ◽  
Real World ◽  
Spatial Orientation ◽  
Physical Environment ◽  
Repeated Measurements ◽  
Starting Position ◽  
Sports Science ◽  
Head Mounted Display ◽  
Promising Tool ◽  
Significant Difference

AbstractVirtual reality (VR) is a promising tool and is increasingly used in many different fields, in which virtual walking can be generalized through detailed modeling of the physical environment such as in sports science, medicine and furthermore. However, the visualization of a virtual environment using a head-mounted display (HMD) differs compared to reality, and it is still not clear whether the visual perception works equally within VR. The purpose of the current study is to compare the spatial orientation between real world (RW) and VR. Therefore, the participants had to walk blindfolded to different placed objects in a real and virtual environment, which did not differ in physical properties. They were equipped with passive markers to track the position of the back of their hand, which was used to specify each object’s location. The first task was to walk blindfolded from one starting position to different placed sport-specific objects requiring different degrees of rotation after observing them for 15 s (0°, 45°, 180°, and 225°). The three-way ANOVA with repeated measurements indicated no significant difference between RW and VR within the different degrees of rotation (p > 0.05). In addition, the participants were asked to walk blindfolded three times from a new starting position to two objects, which were ordered differently during the conditions. Except for one case, no significant differences in the pathways between RW and VR were found (p > 0.05). This study supports that the use of VR ensures similar behavior of the participants compared to real-world interactions and its authorization of use.

VIS: A virtual image system for image-understanding research

1988 ◽  
Vol 18 (5) ◽  
pp. 395-414 ◽  
Author(s):  
David Vernon ◽  
Giulio Sandini
Keyword(s):  
Image Understanding ◽  
Virtual Image ◽  
Image System

scholarly journals Immersive virtual reality in children with upper limb injuries: Findings from a feasibility study

2021 ◽  
pp. 1-14
Author(s):  
Ivan Phelan ◽  
Penny J. Furness ◽  
Heather D Dunn ◽  
Alicia Carrion-Plaza ◽  
Maria Matsangidou ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Range Of Motion ◽  
Feasibility Study ◽  
Upper Limb ◽  
Outpatient Rehabilitation ◽  
Small Scale ◽  
Head Mounted Display ◽  
Limb Injuries ◽  
Custom Made ◽  
Rehabilitation Exercises

PURPOSE: Children who sustain Upper Limb Injuries (ULIs), including fractures and burns, may undergo intensive rehabilitation. The discomfort of therapy can reduce their compliance, limit their range of motion (ROM) and lead to chronic pain. Virtual Reality (VR) interventions have been found to reduce anticipated and procedural pain. This feasibility study aimed to explore perceptions and impacts of a custom-made, fully immersive Head-Mounted Display VR (HMD-VR) experience within a United Kingdom (UK) National Health Service (NHS) outpatient rehabilitation service for children with ULIs. METHODS: Ten children aged 9–16 in one UK Children’s hospital trialled HMD-VR during one rehabilitation session. They, their parents (n = 10), and hospital physiotherapy staff (n = 2) were interviewed about their perceptions of pain, difficulty, enjoyability, therapeutic impacts, benefits, and limitations. Children rated the sessions on enjoyability, difficulty, and pain compared to usual rehabilitation exercises. Physiotherapists were asked to provide range of motion readings. RESULTS: Inductive thematic analysis of interview data generated three themes, ‘Escape through Engagement’; ‘Enhanced Movement’; and ‘Adaptability and Practicality’. Children rated the session as more enjoyable, less difficult and painful than their usual rehabilitation exercises. Findings suggested that HMD-VR was an engaging, enjoyable experience that distracted children from the pain and boredom of therapy. Also, it seemed to enhance the movement they achieved. Participants perceived it was useful for rehabilitation and adaptable to individual needs and other patient groups. Suggestions were made to increase adaptability and build in practical safeguards. CONCLUSION: Findings from this small-scale feasibility study suggested HMD-VR was perceived as usable, acceptable, and effective with potential for further development. Future work could include larger scale trials.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

A quantitative image analysis method for the determination of cocontinuity in polymer blends

1993 ◽  
Vol 51 ◽  
pp. 894-895
Author(s):  
William A. Heeschen
Keyword(s):  
Image Analysis ◽  
Polymer Blends ◽  
Quantitative Measurement ◽  
Morphological Evolution ◽  
Phase Ratio ◽  
Irregular Shapes ◽  
Quantitative Image ◽  
Discrete Domains ◽  
A Domains

Two new morphological measurements based on digital image analysis, CoContinuity and CoContinuity Balance, have been developed and implemented for quantitative measurement of morphology in polymer blends. The morphology of polymer blends varies with phase ratio, composition and processing. A typical morphological evolution for increasing phase ratio of polymer A to polymer B starts with discrete domains of A in a matrix of B (A/B < 1), moves through a cocontinuous distribution of A and B (A/B ≈ 1) and finishes with discrete domains of B in a matrix of A (A/B > 1). For low phase ratios, A is often seen as solid convex particles embedded in the continuous B phase. As the ratio increases, A domains begin to evolve into irregular shapes, though still recognizable as separate domains. Further increase in the phase ratio leads to A domains which extend into and surround the B phase while the B phase simultaneously extends into and surrounds the A phase.

Relationships Between Subjective Ratings and Objective Measures of Performance in Speechreading Sentences

1997 ◽  
Vol 40 (4) ◽  
pp. 900-911 ◽  
Author(s):  
Marilyn E. Demorest ◽  
Lynne E. Bernstein
Keyword(s):  
Hearing Impairment ◽  
Performance Evaluations ◽  
Objective Measures ◽  
Large Individual ◽  
Subjective Ratings ◽  
Objective Performance ◽  
Phonetic Distance ◽  
Stimulus Length ◽  
Measures Of Performance ◽  
Confidence Scale

Ninety-six participants with normal hearing and 63 with severe-to-profound hearing impairment viewed 100 CID Sentences (Davis & Silverman, 1970) and 100 B-E Sentences (Bernstein & Eberhardt, 1986b). Objective measures included words correct, phonemes correct, and visual-phonetic distance between the stimulus and response. Subjective ratings were made on a 7-point confidence scale. Magnitude of validity coefficients ranged from .34 to .76 across materials, measures, and groups. Participants with hearing impairment had higher levels of objective performance, higher subjective ratings, and higher validity coefficients, although there were large individual differences. Regression analyses revealed that subjective ratings are predictable from stimulus length, response length, and objective performance. The ability of speechreaders to make valid performance evaluations was interpreted in terms of contemporary word recognition models.

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