Vibration Dose Research Articles

Whole Body Vibration Exposure on Markers of Bone Turnover, Body Composition, and Physical Functioning in Breast Cancer Patients Receiving Aromatase Inhibitor Therapy: A Randomized Controlled Trial.

Introduction: Women with breast cancer are often prescribed aromatase inhibitors, which can cause rapid loss of bone mass leading to significant potential for morbidity. Vibration training has been shown to be helpful in reducing bone turnover in postmenopausal women without cancer. Aim: To examine the effect of vibration stimulus on markers of bone turnover in breast cancer patients receiving aromatase inhibitors. Methods: Thirty-one breast cancer survivors undergoing treatment with aromatase inhibitors were randomized to vibration stimulus (n = 14) or usual care control (n = 17). Low-frequency and low-magnitude vibration stimulus (27-32 Hz, 0.3g) was delivered in supervised sessions via standing on a vibration platform for 20 minutes, 3 times per week for 12 weeks. The primary outcome was blood markers of bone resorption (serum N-telopeptide X/creatine) and formation (serum type 1 procollagen N-terminal propeptide; P1NP). Other study outcomes body composition as well as measures of physical functioning. Outcomes were compared between groups using analysis of covariance adjusted for baseline values as well as time on aromatase inhibitors. Outcomes: On average, participants were 61.5 years old and overweight (ie, body mass index = 28.5 kg/m2). Following vibration training, there was no significant difference between groups for bone resorption (adjusted group difference 0.5, P = .929) or formation (adjusted group difference 5.3, P = .286). There were also no changes in any measure of physical functioning body composition. Conclusions: Short-term low-magnitude vibration stimulus does not appear to be useful for reducing markers of bone turnover secondary to aromatase inhibitors in breast cancer patients; nor is it useful in improving physical function or symptoms. However, further investigations with larger samples and higher doses of vibration are warranted. Trial Registration: Australian and New Zealand Clinical Trials Registry (ACTRN12611001094965).

Evaluation of Whole-Body Vibration Exposure Among Urban Metro Drivers: Comparing ISO2631-1 and ISO2631-5 Standards to Evaluate Exposure

Background: Excessive vibration is one of the harmful agents in the work environment, and many drivers are inevitably exposed to that during driving. Objectives: Using ISO 2631-1&5 standards in the present study, the evaluation of the whole-body vibration (WBV) exposure was carried among Tehran metro drivers. Methods: In this descriptive cross-sectional study, 23 trains were investigated and the level of exposure to vibration during daily working shift and vibration indicators were evaluated. According to ISO 2631-1, the following 5 factors were measured: the rate of frequency- weight acceleration r.m.s for each axis, the combination of axes, crest factor, peak acceleration, vibration dose value (VDV), and recent equivalent static compressive stress (Sed) and risk (R) factors - estimation criteria for damage to lumbar spine. Results: The results indicated that based on the basic method, the levels of drivers exposure to the vibration are less than the lower limit set by health guidance caution zone (HGCZ), and according to the VDV methods, 4 cases were found to be above the upper limit, 8 cases were within the HGCZ, and the rest were less than the mentioned limit. Moreover, according to the Sed method, 4 drivers had exposures below the lower limit, 7 had exposures within the range of HGCZ, and 12 of the mover the limit. On the other hand, on the basis of R factor, the levels of exposure of the 3 drivers were within the range of HGCZ, while the rest of them experienced the levels lower than that. Conclusions: The results showed that there are several differences among the calculated criteria confirming that some of these indicators may not show a safe limit.

Health risk related to whole-body vibration in agricultural tractor: ballast and displacement speed

Mechanical vibration can lead to health problems in workers during the performance of their professional activi­ties. The objective of this study was to evaluate the vibration incident on the whole body of the agricultural tractor operator in a standard track of vibration tests under different ballast conditions and displacement speeds. A 4x2 AFWD agricultural tractor with 92 kW engine power was tested in four ballast conditions: total ballast (70 kN); solid ballast only (54 kN); liquid ballast only (54 kN); and without any ballast (48 kN), at four working speeds: 1.19 m s -1 ; 1.47 m s -1 ; 1.75 m s -1 and 2.08 m s -1 . The values regarding axle accelerations, the sum of axes for mean accelerations, and the vibration dose value were evaluated by analysis of variance and separation of means (Tukey, p<0.05), in addition to principal components analysis (PCA). Speed was the most influential factor in the vibration generated. The lowest values of mean acceleration and vibration dose value were found in the combina­tion of the lowest speeds with the highest weight of the tractor, while the highest values occurred in the combina­tion of higher speeds with lower weight and liquid ballast. The accelerations obtained on the y axis were more determinant in data behavior than those found in the x and z axes.

Analytical, numerical and experimental assessment of vibration performance in timber floors

The assessment of the dynamic properties and vibration performance of two full-scale timber floor specimens is presented. The specimen set comprised a Timber-Concrete Composite floor and a Cross Laminated Timber floor. The floors, which are characterized by the same length and mass, are located in two separate five-storey timber buildings constructed in the urban area of Trento (Italy). The assessment was conducted by adopting analytical and numerical methods as well as by performing onsite experimental tests. Mock up samples of the floor specimens were also made and tested in laboratory. Multiple analytical methods that are available in literature were evaluated and compared. The Vibration Dose Value (VDV) method, as proposed by ISO 10137 and BS 6472, was used as reference method for the numerical modelling and the laboratory testing. To determine the VDV, loading associated to human walking was simulated. Dynamic identification tests, where the floors were excited by a modal hammer, were also performed in order to investigate the dynamic properties (i.e. natural frequencies, damping and mode shapes) of the floors. Discussion on the vibration performance of the timber floor typologies studied herein and on the effectiveness of the different assessment approaches (i.e. analytical, numerical and experimental) is provided.

Whole-Body Vibrations Associated With Alpine Skiing: A Risk Factor for Low Back Pain?

Alpine skiing, both recreational and competitive, is associated with high rates of injury. Numerous studies have shown that occupational exposure to whole-body vibrations is strongly related to lower back pain and some suggest that, in particular, vibrations of lower frequencies could lead to overuse injuries of the back in connection with alpine ski racing. However, it is not yet known which forms of skiing involve stronger vibrations and whether these exceed safety thresholds set by existing standards and directives. Therefore, this study was designed to examine whole-body vibrations connected with different types of skiing and the associated potential risk of developing low back pain. Eight highly skilled ski instructors, all former competitive ski racers and equipped with five accelerometers and a Global Satellite Navigation System to measure vibrations and speed, respectively, performed six different forms of skiing: straight running, plowing, snow-plow swinging, basic swinging, short swinging, and carved turns. To estimate exposure to periodic, random and transient vibrations the power spectrum density (PSD) and standard ISO 2631-1:1997 parameters [i.e., the weighted root-mean-square acceleration (RMS), crest factor, maximum transient vibration value and the fourth-power vibration dose value (VDV)] were calculated. Ground reaction forces were estimated from data provided by accelerometers attached to the pelvis. The major novel findings were that all of the forms of skiing tested produced whole-body vibrations, with highest PSD values of 1.5–8 Hz. Intensified PSD between 8.5 and 35 Hz was observed only when skidding was involved. The RMS values for 10 min of short swinging or carved turns, as well as all 10-min equivalent VDV values exceeded the limits set by European Directive 2002/44/EC for health and safety. Thus, whole-body vibrations, particularly in connection with high ground reaction forces, contribute to a high risk for low back pain among active alpine skiers.

Analysis of WBV on standing and seated passengers during off-peak operation in KL monorail

In this study, the Whole-Body Vibration (WBV) was analyzed on the standing and seated passenger during off-peak operating hours when train was on the track. The experiments were conducted on two car train at one constant location (bogie-1, which is near to driver’s cabin) during downward direction from KL sentral station towards Titiwangsa station. The aim of this study was to analyze that, in which posture of passenger’s exposures the maximum level of WBV. Since, one passenger was performed the whole journey in standing posture whereas, the other passenger was in seated posture. The result obtained from experiments for the RMS accelerations (Arms), maximum acceleration (Amax) and minimum acceleration (Amin) during the trip. As per standard ISO 2631-1, the daily vibration exposure (A8), Vibration Dose value (VDV) and Crest Factor (CF) of this trip for both standing and sitting orientations were calculated. Results shows that the seated passenger was exposed to longer periods of continuous vibration as compared to the standing passenger. Whereas, the Vibration Dose value (VDV) value was greater than the action value as per ISO 2631-1 and within the limit values. The study concluded that whole body vibration transmitted towards both passengers either standing or seated during their journey. But in overall results comparison of both orientations, the seated passengers gained higher vibration than the standing one.

Effect of Rear Wheel Suspension on Tilt-in-Space Wheelchair Shock and Vibration Attenuation

BackgroundSuspension systems are designed to reduce shock and vibration exposure. An aftermarket rear-wheel suspension system is now available for manual tilt-in-space wheelchairs. ObjectiveTo compare quantifiable shock and vibration on a rigid manual tilt-in-space wheelchair to published data on manual wheelchairs and to determine whether aftermarket rear suspension system will significantly decrease shock exposure when traversing common obstacles. DesignCross-sectional. SettingResearch laboratory. ParticipantsTen healthy non-wheelchair users. MethodsSubjects seated in a manual tilt-in-space wheelchair were pushed over 4 different obstacles (an exterior door threshold, truncated domes, 2-cm descent, and 2-cm ascent) with the chair as manufactured and with the suspension system installed. Main Outcome MeasurementsSuperior/inferior and anterior/posterior accelerations were assessed at the seat pan with and without the use of ISO 2631-1 standards. Peak accelerations were analyzed from the door threshold, 2-cm descent and 2-cm ascent. Root mean square acceleration (RMSa) values were analyzed from the truncated domes, and vibration dose value (VDV) was analyzed for all surfaces. ResultsThere were no differences in time spent over the 4 obstacles between rigid and suspended conditions (P≥.064). Suspension decreased the peak acceleration at the rear wheel when it initially impacted the door threshold, and when the rear wheel traversed the 2-cm descent and ascent (P≤.043). ISO 2631-1 frequency weighting, placing emphasis on frequencies most harmful to humans, also supports suspension reducing peak accelerations at the rear wheel both when it initially impacted and left the door threshold, and when the rear wheel descended 2 cm (P≤.049). Suspension also reduced the truncated dome RMSa as well as the door threshold, 2-cm descent, and total VDV (P≤.041). ConclusionsThe results indicate that rigid manual tilt-in-space wheelchairs respond to rough surfaces in a similar fashion to previously studied rigid wheelchairs. Furthermore, the aftermarket suspension system reduces some aspects of shock and vibration exposure, also consistent with previously studied suspension systems. Level of EvidenceNA

One-way ANOVA model to study whole-body vibration attributes among taxi drivers – An emphasis on the role of speed

Taxi drivers are daily exposed to frequent and prolonged whole-body vibration. This can cause complications such as back pain among them. Since the vibration level depends on many factors, the present study was performed to model the impact of vehicle speed on the attributes of whole-body vibration among the Peugeot 405 taxi drivers. In this experimental study, the whole-body vibration was measured while other variables including tire pressure, engine speed, road gradient, number of passengers, and type of tire, springs, and shock absorbers had been fixed. The measurements were done according to ISO2631–1 at different speeds of 20, 40, 60, and 80 km/h. Increasing the vehicle speed caused an increase in the average value of vibration attributes including Z-axis (vertical) r.m.s. acceleration, 8-h equivalent acceleration, vibration dose value (m/s1.75), and crest factor (P &lt; 0.05). At the speed of 80 km/h, the average vibration dose value (17.6 m/s1.75) exceeded the upper limit of the ISO 2631–1:1997 health caution zone (&gt;17). Further, 8-h equivalent acceleration, at the speeds of 60 and 80 km/h, was beyond the upper limit (&gt;0.9 m/s2). According to the crest factor, increasing speed would cause greater vibration peaks along the Z-axis (worst-case axis). The amount of whole-body vibration is sensitive to speed changes so that urban taxi drivers who are usually driving at low speeds for inner-city transits will be exposed to a lower average value of whole-body vibration. Due to the evident effect of speed on whole-body vibration attributes, it is strongly recommended to be given full consideration to this factor in preparing vibration control plans for vehicles.

Frequency-dependence of discomfort caused by vibration and mechanical shocks

The frequency content of a mechanical shock is not confined to its fundamental frequency, so it was hypothesised that the frequency-dependence of discomfort caused by shocks with defined fundamental frequencies will differ from the frequency-dependence of sinusoidal vibration. Subjects experienced vertical vibration and vertical shocks with fundamental frequencies from 0.5 to 16 Hz and magnitudes from ±0.7 to ±9.5 ms–2. The rate of growth of discomfort with increasing magnitude of motion decreased with increasing frequency of both motions, so the frequency-dependence of discomfort varied with the magnitudes of both motions and no single frequency weighting will be ideal for all magnitudes. At the frequencies of sinusoidal vibration producing greatest discomfort (4–16 Hz), shocks produced less discomfort than vibration with same peak acceleration or unweighted vibration dose value. Frequency-weighted vibration dose values provided the best predictions of the discomfort caused by different frequencies and magnitudes of vibration and shock.Practitioner Summary: Human responses to vibration and shock vary according to the frequency content of the motion. The ideal frequency weighting depends on the magnitude of the motion. Standardised frequency-weighted vibration dose values estimate discomfort caused by vibration and shock but for motions containing very low frequencies the filtering is not optimum.

Correlation between weighted acceleration, vibration dose value and exposure time on whole body vibration comfort levels evaluation

Every environment offers stimuli to subjects. Some of these stimuli can be harmful to the human health, like vibration, depending on the intensity and/or exposure duration, among other factors. Even if the vibration is not harmful, it may cause discomfort. The ISO2631-1 (1997) Standard says that two exposures are equivalent when they have the same vibration energy. For that, it uses the exposure duration and the weighted acceleration or Vibration Dose Values (VDV) to calculate the equivalence, being those terms a power of 2 or 4, respectively, in the equivalence formula. Despite that, Annex C of the Standard states that there is no conclusive evidence to support a time dependency of vibration on comfort, reporting that some studies uses the frequency-weighted rms acceleration to calculate the dose of vibration received during an expected daily exposure (called eVDV – for Estimated). It should be expected that the same vibration energy would cause equivalent effect (on health or comfort). In order to verify this hypothesis, two frequency weighted acceleration values, measured according to ISO2631-1 (1997, 2010), were adopted, considering four different exposure durations in a way to reach three pre-established eVDV. The same frequency was considered for all studied situations to easy the comparison. To say that the time, the exposure duration or the VDV by itself are important parameters on the vibration influence can be naive and that was not confirmed in this study. The conclusion is that these variables superimpose themselves mutually, having different influences according to the other parameters involved.

Influence of Type of Frequency Weighting Function On VDV Analysis

Transport vibrations are the subject of many research, mostly their influence on structural elements of the building is investigated. However, nowadays, especially in the centres of large cities were apartments, residential buildings are closer to the transport vibration sources, an increasing attention is given to providing vibrational comfort to humans in buildings. Currently, in most countries, two main methods of evaluation are used: root mean squared method (RMS) and vibration dose value (VDV). In this article, VDV method is presented and the analysis of the weighting functions selection on value of VDV is made. Measurements required for the analysis were made in Krakow, on masonry, residential, two storey building located in the city centre. The building is subjected into two transport vibration sources: tram passages and vehicle passages on very close located road. Measurement points were located on the basement wall at ground level to control the excitation and in the middle of the floor on the highest storey (in the place where people percept vibration). The room chosen for measurements is located closest to the transport excitation sources. During the measurements, 25 vibration events were recorded and analysed. VDV values were calculated for three different weighting functions according to standard: ISO 2631-1, ISO 2631-2 and BS-6841. Differences in VDV values are shown, but also influence of the weighting function selection on result of evaluation is also presented. VDV analysis was performed not only for the individual vibration event but also all day and night vibration exposure were calculated using formulas contained in the annex to the standard BS-6841. It is demonstrated that, although there are differences in the values of VDV, an influence on all day and night exposure is no longer so significant.

Human responses to wave slamming vibration on a polar supply and research vessel

A polar supply and research vessel is pre-disposed to wave slamming which has caused complaints among crew and researchers regarding interference with sleep, equipment use and research activities. The present work undertook to survey passenger claims of sleep interference, disturbed motor tasks and equipment damage as a result of wave slamming during normal operations of this vessel. The hypothesis was investigated that whole-body vibration metrics from ISO 2631-1 are potentially suitable for the prediction of human slamming complaints. Full-scale acceleration measurements were performed and wave slamming events were subsequently identified from the human weighted acceleration time histories. A daily diary survey was also conducted to gather the human response. The vibration caused by wave slamming was found to be strongly correlated with sleep disturbances and activity interference. Sleep and equipment use were found to be the most affected parameters by slamming. Daily vibration dose values were determined by accumulating the vibration as a result of slamming over 24 h periods. This metric accounted for increased magnitudes and frequency of slamming incidents and proved to be the best metric to represent human responses to slamming vibration. The greatest percentage of activities affected by slamming related to sleep regardless of daily cumulative VDV magnitude. More than 50% of the recorded responses related to sleep when the daily cumulative VDV ranged between 8.0 m/s1.75–10.0 m/s1.75. The peak vertical vibration levels recorded on the vessel reach magnitudes which are associated with sleep disturbance in environments where acoustic noise is present.

Human perception of vibrations according different assessment methods

Human perception of vibration could be the basic parameter in designing new buildings subjected to different type of transport vibrations. Humans are more sensitive for vibrations then building structure. In an increasingly urbanized city centres people are exposed to vibrations from different transport sources such as: tramways, railways, heavy truck traffic or subway especially when considered shallow underground. The aim of this paper is to investigate the use of two different evaluation methods of human perception of vibrations. Methods chosen for evaluation are: the basic root mean squared (RMS) method and the additional method of evaluation vibration dose value (VDV). The building chosen for analysis is subjected to three different vibration sources: tram, heavy truck and subway passages. It is located in Warsaw where is a shallow underground which could have significant influence on human response to vibrations because vibrations from this kind of source is more perceptible on lower floors. That is why measurement points were located in the middle of the floor on the ground floor and on the top floor. The registered signal from the three different sources of vibration was analysed according to RMS and VDV procedure included in ISO standard. RMS and VDV methods were compared with each other.

Design method for a powertrain mounting system to decrease the vehicle key on/off vibrations

Five dynamic response evaluation indices from the viewpoint of the powertrain mount system and the vehicle system during the vehicle key on/off periods (i.e. the engine start and stop) are proposed. By analysis using different methods to minimize the powertrain vibration, it was found that an increase in the mount system damping can decrease the vehicle key on and key off vibration. For this reason, in this paper a semi-active hydraulic damping strut is designed and made which can provide high damping for a mount system when the vehicle key on/off but switches to lower damping to isolate high-frequency vibrations under normal conditions. The calculated longitudinal acceleration of the powertrain, the jerk of the powertrain, the dynamic force of the mount and the vibration dose value for a vehicle with the semi-active hydraulic damping strut and without the semi-active hydraulic damping strut are compared on the basis of the excitation force identified for the powertrain using a 13-degree-of-freedom vehicle model. Experiments were carried out, and the results show that the use of the semi-active hydraulic damping strut can decrease the engine start and stop vibrations to a large extent. Finally, the experimental results are compared with the calculated values from the 13-degree-of-freedom vehicle model.

Dynamics and Control of Clutchless Automated Manual Transmissions for Electric Vehicles

This paper presents a study of the dynamics and control of clutchless automated manual transmissions (CLAMT) for the purpose of investigating the system behavior during up and down shifts. To achieve this, a multibody dynamic model of the proposed powertrain is implemented to simulate the transient behavior of the system, including a direct current (DC) equivalent model of the electric machine (EM) and a synchronizer mechanism model. Closed-loop control of motor speed and torque is used in conjunction with synchronizer mechanism actuation to functionally achieve gear shifting without the need for a primary friction clutch. This includes nested torque–speed closed-loops to implement alternative motor control functionalities at different stages of gear change. To evaluate the performance of shift control, shift metrics including longitudinal jerk, vibration dose value (VDV), and shifting duration are evaluated from simulation results. These results demonstrate the most significant impact on the transient response of the powertrain results from the reduction and reinstatement of motor torque during shift control. Speed control of the motor during the shift transient directly impacts on the duration of shifting, but not the transient response of the powertrain.

Investigation of human body vibration exposures on haul trucks operating at U.S. surface mines/quarries relative to haul truck activity

Workers who operate mine haul trucks are exposed to whole-body vibration (WBV) on a routine basis. Researchers from the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Mining Research Division (PMRD) investigated WBV and hand-arm vibration (HAV) exposures for mine/quarry haul truck drivers in relation to the haul truck activities of dumping, loading, and traveling with and without a load. The findings show that WBV measures in weighted root-mean-square accelerations (aw) and vibration dose value (VDV), when compared to the ISO/ANSI and European Directive 2002/44/EC standards, were mostly below the Exposure Action Value (EAV) identified by the health guidance caution zone (HGCZ). Nevertheless, instances were recorded where the Exposure Limit Value (ELV) was exceeded by more than 500 to 600 percent for VDVx and awx, respectively. Researchers determined that these excessive levels occurred during the traveling empty activity, when the haul truck descended down grade into the pit loading area, sliding at times, on a wet and slippery road surface caused by rain and overwatering. WBV levels (not normalized to an 8-h shift) for the four haul truck activities showed mean awz levels for five of the seven drivers exceeding the ISO/ANSI EAV by 9–53 percent for the traveling empty activity. Mean awx and awz levels were generally higher for traveling empty and traveling loaded and lower for loading/dumping activities. HAV for measures taken on the steering wheel and shifter were all below the HGCZ which indicates that HAV is not an issue for these drivers/operators when handling steering and shifting control devices.

Kineto-dynamic design optimisation for vehicle-specific seat-suspension systems

ABSTRACTDesigns and analyses of seat-suspension systems are invariably performed considering effective vertical spring rate and damping properties, while neglecting important contributions due to kinematics of the widely used cross-linkage mechanism. In this study, a kineto-dynamic model of a seat-suspension is formulated to obtain relations for effective vertical suspension stiffness and damping characteristics as functions of those of the air spring and the hydraulic damper, respectively. The proposed relations are verified through simulations of the multi-body dynamic model of the cross-linkage seat-suspension in the ADAMS platform. The validity of the kineto-dynamic model is also demonstrated through comparisons of its vibration transmission response with the experimental data. The model is used to identify optimal air spring coordinates to attain nearly constant natural frequency of the suspension, irrespective of the seated body mass and seated height. A methodology is further proposed to identify optimal damping requirements for vehicle-specific suspension designs to achieve minimal seat effective amplitude transmissibility (SEAT) and vibration dose value (VDV) considering vibration spectra of different classes of earthmoving vehicles. The shock and vibration isolation performance potentials of the optimal designs are evaluated under selected vehicle vibration superimposed with shock motions. Results show that the vehicle-specific optimal designs could provide substantial reductions in the SEAT and VDV values for the vehicle classes considered.

Predicting Whole-Body Vibration Exposure in Canadian Prairie Farmers.

Direct workplace whole-body vibration exposure assessment provides ecological validity for evaluating health risk in epidemiological studies, yet it is complex and expensive in practical applications. Exposure prediction modeling could be a cost-efficient alternative to directly assessing occupational vibration exposures. The objective of this study was to model directly measured whole-body vibration exposures with predictors from machinery, farm, and self-reported characteristics among Canadian prairies farmers. As per ISO 2631-1, whole-body vibration data were measured on the seat surface at three axes (x, y, z), then summarized into vector sums of the root-mean-squared (RMS) acceleration and the vibration dose value (VDV). All candidate predictors were obtained via questionnaires and onsite observations. A total of 87 whole-body vibration measurements were collected from 40 male farm workers located at 21 central Saskatchewan farms. Using log-transformed RMS and time-standardized VDV outcomes, modeling started from the bivariate analysis where predictors with P-values < 0.2 were considered eligible for multivariate analysis. With random effects of 'farm' and 'farmer', a series of mixed-effects models were constructed through the manual backward elimination method. Final models were internally validated by 1000 bootstrapped samples. The RMS model explained 47.7% of the variance in the directly measured RMS vector sum, with 42.7% obtained from five predictors of 'horsepower', 'transmission', 'vehicle year', 'jerk/jolt frequency', and 'seat bottom-out frequency', while the VDV model explained 19.5% of the variance in the directly measured VDV vector sum, with 11.6% described by the same five predictors as the RMS model. Predictive ability of the RMS model among 1000 bootstrapped samples can be anticipated to range from 14.3 to 69.1%, which may be considered adequate as exposure assessment tool for uses of epidemiological studies. The percentage of variance explained ranged from 0 to 40.5% for the VDV model, which is not robust and therefore likely not appropriate for use in survey-based exposure prediction. Whole-body vibration exposure modeling remains valuable, but is challenging in farming; the described model variance may increase with a more comprehensive list of candidate variables collected and quantified at machinery, farm, and farmer level. Predictors identified in the current and future models may provide a better understanding of how whole-body vibration exposure is modified, guide farmer's future decision on updating equipment, and allow for the development and initiation of interventions.

Neural Network and Training Strategy Design for Train Drivers’ Vibration Dose Simulation

Vibration can cause professional illnesses in train drivers, giving also rise to lawsuits to the employer. A possible cause may be the lack of systematic vibration estimation processes, due to operational complexities, subjectivities involved and the cost of dedicated tests. Estimation quality may be improved by using a driver seat model along with cabin floor vibration data acquired during the train dynamic approval tests. However, due to the nonlinearities present, analytical models frequently show inaccurate results.

Dynamic modelling and simulation of a manual transmission based mild hybrid vehicle

This paper investigates the development of a mild hybrid powertrain system through the integration of a conventional manual transmission equipped powertrain and a secondary power source in the form of an electric motor driving the transmission output shaft. The primary goal of this paper is to study the performance of partial power-on gear shifts through the implementation of torque hole filling by the electric motor during gear changes. To achieve this goal, mathematical models of both conventional and mild hybrid powertrain are developed and used to compare the system dynamic performance of the two systems. This mathematical modelling is used to run different simulations for gear-shift control algorithm design during system development, allowing us to evaluate the achievable performance and its dependency on system properties. The impact of motor power on the degree of torque hole compensation is also investigated, keeping in mind the practical limits to motor specification. This investigation uses both the output torque, vehicle speed as well as vibration dose value to evaluate the quality of gearshifts at different motor sizes. Results demonstrate that the torque hole may be eliminated using a motor power of 50kW. However, the minimum vibration dose value during gear change is achieved using a peak power of 16–20kW.