The purpose of this study was to investigate the effect of two views on motion sickness caused by low-frequency roll motion in the laboratory. Fifteen healthy male subjects participated in the study and were exposed to 30 min of 0.25 Hz roll oscillation at an angle of rotation (±5°). Subjects sat on a rigid seat with one of two visual scenes each session: (i) viewing 360° videos through virtual reality (VR) head-mounted display (HMD) device and (ii) reading articles on a monitor in a closed cabin. Ratings of motion sickness were obtained at 1 min intervals. The mean illness ratings of subjects for all visual conditions increased over the 30 min exposure to motion. There was significantly less sickness in the HMD condition than in the monitor condition. The findings suggest a beneficial effect of the HMD view on the severity of sickness. However, the HMD view had no effect on the sickness experienced by those vulnerable to sickness caused by exposure to motion or use of VR. It was concluded that the visual activity had a significant influence on motion sickness induced by 0.25 Hz roll oscillation with an angle of rotation (±5°), and the applications of VR could be implemented to further reduce motion sickness.

This study aimed to investigate the acute effect of grip and feed exertions on the vascular system at the fingers during exposure to hand-arm vibration (HAV), and to identify which active hand force situation would have the most effect on finger vascular function. A total of 12 individuals attended the test, and each of them were subjected to eight sets of force-and-vibration situations: four with combinations of forces and vibration, and four control ones with only hand forces applied. The vibration stimulus was applied on the right hand at 2.75 m/s² with a frequency of 125 Hz for three minutes, during which the application of grip and feed forces were set at either 10 N or 50 N. The weakening of the finger vascular function was reflected by a reduction in the finger blood flow (FBF) and finger skin temperature (FST). They were tested on both hands at fixed intervals before, during and after the exposure for in-time measurement. Hand forces resulted in clear reductions in FBF and FST in exposed right fingers whether the force was exerted solely or combined with vibration. The greater the hand force (especially grip force), the stronger the vascular response, while the additional reductions in FBF and FST from vibration were not significant. In the non-exposed left fingers, no significant changes in finger circulation occurred in response to force or vibration. Generally, vibration-induced acute finger vasoconstriction was affected by the hand forces, in which hand force seemed to play a more important part than vibration. A larger grip force would lead to a greater loss in the digital circulation than feed force. Thus, the level of hand force exerted on the tool handle should be limited to reduce the risk of harm from HAV.

This paper investigates the joint authentication of topology and geometry information of 2D engineering computer-aided design graphics, which focus more on topological modeling than geometric modeling of objects. A robust hashing scheme is proposed for joint topology and geometry authentication. The covariance matrices of descriptors are explored to fuse and encode both topology and geometry features of different types into a compact representation. First, a normalized binary shape texture is rendered for each geometric object through the render-to-texture technique. Then, for each geometric object, geometry features are computed based on statistical features that are extracted from image rings. Additionally, topology features are generated according to the topological relations among joint objects. To generate hash codes of the graphic, all geometric objects are first grouped according to their geometry features. Then, for each group, the covariance matrices of descriptors are applied to fuse both the topology and geometry features of all objects, and the intermediate hash codes of each group are computed based on the covariance matrices. The final hash sequence is formed by concatenating the intermediate hash codes that correspond to each group. Secret keys are introduced into both feature extraction and hash construction. The hashes are robust against topology-preserving graphic manipulations and sensitive to malicious attacks. By decomposing the hashes, the locations of tampered objects can be determined. Experimental results are presented to evaluate the performance and show the effectiveness of the method.

Background: to investigate the acute effects of vibration and force level on vibrotactile perception following short-term exposure to hand-arm vibration (HAV). Methods: 12 individuals attended the test, and each of them completed a set of grasping tasks between 10 N and 80 N while being exposed to four intensities of HAV at 125 Hz, ranging from 5.5 to 44.0 m/s² (unweighted), for three minutes. The vibrotactile perception threshold (VPT, at 125 Hz) on the fingertip was assessed before and after the exposure. Results: Vibration caused considerable reductions in VPT, and the higher the HAV amplitude, the more the VPT shifted. There were also noticeable VPT shifts brought on by the force increase, but the force increase from 40 N to 80 N could not make more of a difference at higher vibration levels. Conclusions: Vibrotactile perception was sensitive to the vibration level, and was affected by the applied hand force when the vibration intensity was modest. With high vibration levels, the further sensorineural response to the force is limited after the force reaches a certain level.

The palmar surface (on tool surface) has been defined in ISO 5349-1 as a value of the amount of vibration transmitting to the hand and arm from on-body vibration magnitude. They showed the concept of on-body vibration measurement based on the relationship between the temporary threshold shift (TTS) of the vibrotactile perception threshold (VPT) and the on-body vibration measurement values. However, they did not show that the effectiveness of ISO 5349-1 Annex D for various factors transmitting to the hand was unknown. Therefore, the purpose of this paper is to clarify the new considerations of on-body vibration measurement equipment and to demonstrate the necessity of on-body measurement equipment.