The influence of vibration on seated human drowsiness.

Although much is known about human body vibration discomfort, there is little research data on the effects of vibration on vehicle occupant drowsiness. A laboratory experimental setup has been developed. Vibration was applied to the volunteers sitting on the vehicle seat mounted on the vibration platform.

A cross sectional study on hand-arm vibration syndrome among a group of tree fellers in a tropical environment.

This study aimed to explore the clinical characteristics of hand arm vibration syndrome (HAVS) in a group of tree fellers in a tropical environment. We examined all tree fellers and selected control subjects in a logging camp of central Sarawak for vibration exposure and presence of HAVS symptoms utilizing vibrotactile perception threshold test (VPT) and cold water provocation test (CWP). None of the subjects reported white finger.

A comparison of hand-arm vibration syndrome between Malaysian and Japanese workers.

Objectives: The aim of this study was to investigate the clinical characteristics of HAVS in a tropical environment in comparison with a temperate environment.

Methods: We conducted a series medical examinations among the forestry, construction and automobile industry workers in Malaysia adopting the compulsory medical examination procedure used by Wakayama Medical University for Japanese vibratory tools workers. We matched the duration of vibration exposure and compared our results against the Japanese workers.

Dose-response relationship between hand-transmitted vibration and hand-arm vibration syndrome in a tropical environment.

Objectives: The dose-response relationship for hand-transmitted vibration has been investigated extensively in temperate environments. Since the clinical features of hand-arm vibration syndrome (HAVS) differ between the temperate and tropical environment, we conducted this study to investigate the dose-response relationship of HAVS in a tropical environment.

Methods: A total of 173 male construction, forestry and automobile manufacturing plant workers in Malaysia were recruited into this study between August 2011 and 2012.

Health risk evaluation of whole-body vibration by ISO 2631-5 and ISO 2631-1 for operators of agricultural tractors and recreational vehicles.

This paper presents experimental research evaluation of the vibration exposure for the health risk prediction during vehicle operation. The vibration measurements were carried out on a recreational vehicle and two types of agricultural tractors. The vibration levels were measured for different surfaces and vehicle speed conditions.

The clinical features of hand-arm vibration syndrome in a warm environment--a review of the literature.

Unlabelled: The internationally accepted limit values and the health effects of hand-transmitted vibration exposure have been described extensively in the literature from temperate climate countries but not from a tropical climate environment.

Objectives: We conducted a systematic review of the health effects of hand-transmitted vibration exposure in tropical countries to determine the characteristics of hand-arm vibration syndrome in a warm environment and compared the findings with the results of the systematic reviews published by the US NIOSH.

Methods: We searched major medical databases including MEDLINE, PubMed, Embase, CINAHL, Ovid and Cochrane based on the terms "hand arm vibration syndrome," "hand transmitted vibration," "vibration white finger" and "Raynaud" up to January 2011.

The characteristics of vibrotactile perception threshold among shipyard workers in a tropical environment.

The objectives of this study are to determine the prevalence of hand-arm vibration syndrome (HAVS) and the characteristics of the vibrotactile perception threshold (VPT) among users of hand-held vibrating tools working in a tropical environment. A cross sectional study was done among 47 shipyard workers using instruments and a questionnaire to determine HAVS related symptoms. The vibration acceleration magnitude was determined using a Human Vibration Meter (Maestro).

Subjective ratings of whole-body vibration for single- and multi-axis motion.

Real-world whole-body vibration exposures comprise motion in fore-aft, lateral, and vertical directions simultaneously. There can also be components of roll, pitch, and yaw. If evaluating vibration with respect to human response, most investigators will use methods defined in ISO 2631-1.

Gender difference in subjective response to whole-body vibration under standing posture.

Purpose: The aim of this study was to examine whether there exist gender differences in subjective response to whole-body vibration (WBV) under standing posture.

Methods: Totally twenty-four participants (twelve males and twelve females) rated the discomfort of the test stimuli. The test stimuli included fore-and-aft (x), lateral (y), and vertical (z) vibration of three intensity levels (0.

Apparent mass and seat-to-head transmissibility responses of seated occupants under single and dual axis horizontal vibration.

The apparent mass and seat-to-head-transmissibility response functions of the seated human body are investigated under exposures to fore-aft (x), lateral (y), and combined fore-aft and lateral (x and y) axis whole-body vibration. The experiments were performed to study the effects of hands support, back support and vibration magnitude on the body interactions with the seat pan and the backrest, characterised in terms of fore-aft and lateral apparent masses and the vibration transmitted to the head under single and dual-axis horizontal vibration. The data were acquired with 9 subjects exposed to two different magnitudes of vibration applied along the individual x- and y- axis (0.

Determination of backrest inclination based on biodynamic response study for prevention of low back pain.

Whole-body vibration experiments with subjects under vertical vibration were performed to examine and evaluate effects of backrest inclination on vibration transmitted through seats to the human body by using biodynamic response parameters represented by apparent mass (APMS) and vibration power absorption (VPA). The biodynamic response parameters of twelve male subjects, exposed to vertical random vibration at 0.8 m/s(2) r.

Establishment of one-axis vibration test system for measurement of biodynamic response of human hand-arm system.

Prolonged exposure to hand-arm vibration (HAV) due to use of hand-held power tools leads to an increased occurrence of symptoms of disorders in the vascular, neurological, and osteo-articular systems of the upper limbs called hand-arm vibration syndrome (HAVS). Biodynamic responses of the hand-arm system to vibration can be suggestive parameters that give us better assessment of exposure to HAV and fundamental data for design of low-vibration-exposure power tools. Recently, a single axis hand-arm vibration system has been installed in the Japan National Institute of Occupational Safety and Health (NIOSH).

Vibration-isolating performance of cotton work gloves based on newly issued JIS T8114.

The mean vibration transmissibility values were measured for cotton work gloves commonly used in vibration-generating workplaces to evaluate the vibration isolating performance of cotton work gloves. The mean vibration transmissibility values of work cotton gloves were compared with those of four types of anti-vibration gloves measured in the same way. All the measurements were performed based on the newly issued JIS T8114 that is identical to ISO10819.

A pilot study of gene expression analysis in workers with hand-arm vibration syndrome.

The purpose of this pilot study was to examine differences in gene expressions by cDNA microarray analysis of hand-arm vibration syndrome (HAVS) patients. Vein blood samples were collected and total RNA was extracted. All blood samples were obtained in the morning in one visit after a standard light breakfast.

Subjective scaling of hand-arm vibration.

The purpose of this research was to establish a scale for comfort with regard to hand-arm vibration using the category judgment method and to validate the frequency-weighting method of the ISO 5349-1 standard. Experiments were conducted using random signals as stimuli. These stimuli consisted of three types of signal, namely designated stimulus F, with flat power spectrum density (PSD) ranging from 1 to 1,000 Hz, stimulus H with PSD which became 20 dB higher at 1,000 Hz than at 1 Hz, and stimulus L that had a PSD 20 dB lower at 1,000 Hz.

The apparent mass of the seated human exposed to single-axis and multi-axis whole-body vibration.

Most workplaces where workers are exposed to whole-body vibration involves simultaneous motion in the fore-and-aft (x-), lateral (y-) and vertical (z-) directions. Previous studies reporting the biomechanical response of people exposed to vibration have almost always used single-axis vibration stimuli. This paper reports a study where apparent masses of 15 subjects were measured whilst exposed to single-axis and tri-axial whole-body vibration.

Comparison of the apparent mass during exposure to whole-body vertical vibration between Japanese subjects and ISO 5982 standard.

Objective: The purpose of this study was to investigate the apparent mass of the sitting human body and to compare it with current experimental data and the ISO 5982 standard impedance model.

Method: The apparent mass of the seated human body in the vertical direction was measured. Twelve male subjects were exposed to random whole-body vibration of frequency range (1-20 Hz), with a vibration excitation level of 1.

Effect of backrest and torso twist on the apparent mass of the seated body exposed to vertical vibration.

Occupational exposure to whole-body vibration is often combined with a requirement to perform twisting actions. This paper reports a study where the effect of twisting on the biomechanical response of the seated person was investigated. Twelve male subjects were exposed to vertical random whole-body vibration at 0.

Necessary research for standardization of subjective scaling of whole-body vibration.

Researches into the relationship between the physical quantity of vibration and the subjectively perceived quantity become important in designs for the vibration environment. Subjective experimental methods to obtain the relationship between the physical quantity of vibration and the subjectively perceived quantity are different depending on the design objectives which consider the human sense of vibration characteristic. In this review, the following are outlined: (i) fundamental methods for obtaining the design objectives for vibration environments; (ii) reported findings on the physical quantity of vibration environments and the human characteristics of sense vibration; and (iii) problems with and limits of the ISO 2631-1 standard, which defines the subjective response of the ride comfort in public transportation.

Equal sensation curves for whole-body vibration expressed as a function of driving force.

Previous studies have shown that the seated human is most sensitive to whole-body vertical vibration at about 5 Hz. Similarly, the body shows an apparent mass resonance at about 5 Hz. Considering these similarities between the biomechanical and subjective responses, it was hypothesized that, at low frequencies, subjective ratings of whole-body vibration might be directly proportional to the driving force.

Comparison of the apparent mass of the seated human measured using random and sinusoidal vibration.

Exposure to whole-body vibration is generally accepted as being a risk factor for low back pain and therefore exposure to vibration should be minimised. The results of previous laboratory based research investigating the biomechanical response of the seated human to vibration has been used to develop models that can be used within tools that are capable of predicting the response of seats. Several studies in the literature have reported apparent masses of seated human subjects whilst exposed to either random or sinusoidal vibration.

Evaluation of whole-body vibration by the category judgment method.

The purpose of this research is to establish a scale for comfort with regard to whole-body vibration by the category judgment method. Experiments were conducted with random signals as stimuli. These stimuli consisted of three types of signal, namely stimulus F, with flat PSD (Power Spectrum Density) ranging from 1 to 100 Hz, stimulus H with PSD, which became 20 dB higher at 100 Hz than at 1 Hz, and stimulus L that had a PSD 20 dB lower at 100 Hz.

A pilot study of reference vibrotactile perception thresholds on the fingertip obtained with Malaysian healthy people using ISO 13091-1 equipment.

The purpose of this paper is to clarify the reference vibrotactile perception thresholds (VPT) for healthy people in Malaysia. The measurement equipment standard, ISO 13091-1, of the vibrotactile perception thresholds for the assessment of nerve dysfunction and the analysis and interpretation of measurements at the fingertips standard, ISO 13091-2, were published in ISO/TC108/SC4/WG8 on 2001 and 2003 individually. In the ISO 13091-2 standard, the reference VPT data were obtained from few research papers.

Effects of seat-back angle and accelerometer height at the seat-back on seat-back x axis r.m.s. acceleration in filed experiments according to the ISO2631-1 standard.

The effects of seat-back angle and accelerometer height at the seat-back on seat-back x-axis frequency-weighted root-mean-square (r.m.s.