Prediction of frictional braking noise based on brake dynamometer test and artificial intelligent algorithms

Based on brake noise dynamometer test data, combined with the artificial intelligent algorithms, frictional braking noise is quantitatively analyzed and predicted in this study. To achieve this goal, a frictional braking noise prediction method is indicatively proposed, which consists of two main parts: first, based on the experimental data obtained from the brake noise dynamometer tests, and combining with the improved Long-Short-Term Memory (LSTM) algorithm, the coefficients of friction (COFs) are predicted under various braking test conditions. Then, based on the predicted braking COFs and other selected critical braking parameters, the quantitative prediction of frictional braking noise is obtained by means of the optimized eXtreme Gradient Boosting (XGBoost) algorithm. Finally, the inherent features of the XGBoost algorithm are employed to qualitatively analyze the importance of the main factors affecting the frictional braking noise. The prediction algorithms of COFs and frictional braking noise are validated by the brake dynamomter test data, and the R2 (R square) scores of both the LSTM and XGBoost prediction algorithms are 0.9, which verifies the feasibility of both algorithms. The main contribution of this work is to predict the braking noise based on a large set of test data and combined with the LSTM and XGBoost artificial intelligent algorithms, which can significantly save time for the brake system development and braking performance testing, and has significance to the rapid prediction of braking frictional noise and fast NVH (noise, vibration, and harshness) optimal design of frictional braking systems.

Influence of a multidimensional music-based exercise program on selected cognitive and motor skills in dementia patients—a pilot study

One of the most common causes of needing care in old age is dementia. In order to enjoy a pleasant retirement for people with dementia, it is essential for them to maintain their independence. Studies have shown that a combination of physical activity and music has positive effects on dementia patients. Therefore, this study aimed to investigate the feasibility of implementing a multidimensional music-based exercise program for dementia patients and the effects on an intervention group (IG) compared to a control group (CG, usual care). The study design was based on a 12-week intervention with two (IG/CG) by two (pretest/posttest) parallel groups and block randomization with unequal group sizes. Participants had to be able to move independently or with a walker and not have severe cardiovascular disease or cardiac arrhythmias. Fifty-three blinded dementia patients (age: 83.63 ± 6.03 years) from inpatient facilities participated in the study and were assigned from the exercise instructors to IG (n = 34) and CG (n = 19). The primary outcomes were feasibility (Observation sheet), modified Chair Rising test, Timed Up and Go test, hand dynamometer test, FICSIT‑4 (Frailty and Injuries: Cooperative Studies of Intervention Techniques), and drop bar test. Secondary endpoints included: verbal fluency (“animals”), the Mini-Mental State Examination, memory, Trail Making Test A, and Qualidem. Forty-nine subjects were analyzed (IG = 32; CG = 17). There were significant differences between the groups in the modified Chair Rising test (p = 0.033), FICSIT‑4 (p = 0.035), and Timed Up and Go test (p = 0.005) at posttest, which showed improved performance of the IG compared to the CG. The IG additionally showed improvements in the modified Chair Rising test (p = 0.000), drop bar test (p = 0.033), hand dynamometer test (p = 0.001), Timed Up and Go test (p = 0.000), verbal fluency (p = 0.002) and Trail Making Test A (p = 0.04) after 12 weeks. There were no adverse events or side effects. The multidimensional music-based exercise program could be performed by the dementia patients and was well received. The improved functional mobility could contribute to a lower risk of falls and thus maintain independence. For the follow-up study, the number of subjects, randomization, and parameters should be considered.

Effect of Divided Exhaust Period in a High Efficiency TGDI Engine

The divided exhaust period (DEP) concept was applied to a high-efficiency gasoline engine and its impact on various engine performance aspects were investigated. To this end, key design parameters of DEP components were optimized through 1-D engine simulation. The designed DEP components were fabricated and experimental verification was performed through an engine dynamometer test. The developed DEP engine shows suitable performance for electrified vehicles, with a maximum thermal efficiency of 42.5% as well as a wide sweet spot area of efficiency over 40%. The improvement in thermal efficiency was mainly due to a reduction in pumping loss. Notably, the reduction in pumping loss was achieved under high exhaust gas recirculation (EGR) flow conditions, where further improvements in fuel consumption could be achieved through a synergistic combination of DEP implementation and high dilution combustion. Furthermore, a significantly improved catalyst light-off time, uncharacteristic in turbocharged engines, was confirmed through a simulated cold-start catalyst heating engine test.

Gender Differences in Absolute and Relative Values of Hand Dynamometer Test with 9 and 10-Year Old Children From the Skopje Region in R.N. Macedonia

Background. Handgrip strength test is applied both to adults and children to indicate muscular fitness as well as the nutritional and health status. It differs in adults and adolescents depending on the gender. However, it is not clear whether a difference exists also in children at 9 to 10 years of age, and what are the factors that influence it. The goal of the research was to determine the absolute and relative values of the hand dynamometer test with healthy Macedonian boys and girls aged 9 and 10 from the Skopje region as well as to determine the factors that affect the handgrip strength at that age. Materials and methods. The research was conducted on a sample of 775 children (boys n = 386; girls n = 389), whereby the following characteristics were measured: handgrip strength, weight, height, body fat percentage, muscle mass percentage and the body mass index (BMI) was calculated. The maximum handgrip strength was measured with a digital Takei TKK 5101 dynamometer. Results. The research found that there are statistically significant differences in the absolute values obtained in the hand dynamometer test between healthy boys and girls in Macedonia at 9 and 10 years of age. On the basis of the results obtained from the research, one can conclude that the results of the hand dynamometer test are affected by age, gender and body composition. Conclusion. Based on the increasing predominance of children’s obesity, the present study can provide clinicians and researchers with an insight how body composition influences muscular fitness, and can serve policy-makers to develop gender-specific strategies about body-weight management and promotion of muscular performance among children and adolescents.

A Digital Displacement Hydrostatic Wind-turbine Transmission

In 1984 a hydrostatic wind-turbine transmission with ‘secondary control’ was proposed by Stephen Salter using the, then only conceptual, Digital Displacement® (DD) principle for controlling the flow of the primary, rotor-driven, ring-cam pump. This transmission ‘could achieve the correct ratio of tip-speed to wind-speed in conjunction with true synchronous generation’. In the following years DD machines were progressively developed. To start with they were relatively small in capacity but the power ratings were systematically increased, until it seemed that a high-power hydrostatic wind-turbine transmission might indeed be feasible. In 2006, Artemis Intelligent Power (Artemis), a company that had been formed from Salter's original university team, began working on a megawatt-scale, hydrostatic, wind-turbine transmission based on new pump and motor designs. In 2011 Artemis completed a 1.5 MW transmission and dynamometer test-rig. This was one of the largest hydraulic transmissions ever made and, with a shaft-to-shaft efficiency of 93%, one of the most efficient. Using secondary control to respond rapidly to gusting wind and to instantaneous grid faults, it was also the most controllable. This paper discusses the design of the transmission and test-rig and presents the results of steady-state efficiency tests. Subsequent papers will describe systematic experimental work to account for the various energy losses and to develop a comprehensive simulation model of the DD wind-transmission.

Brake Noise Reduction Method Based on Monte Carlo Sampling and Particle Swarm Optimization

Brake noise is one of the principal components of vehicle noise and is also one of the most critical measures of vehicle quality. During the braking process, the occurrence of brake noise has a significant relationship with the working conditions of the brake system. In the present study, dynamometer test data and the finite element method (FEM) were used to analyze the direct and indirect effects of variations in the working parameters on the brake noise, and a brake noise reduction method was developed. With this method, Monte Carlo sampling was used to consider variations in the parameters of the brake lining during the braking procedure, and the particle swarm optimization method was used to calculate the optimal parameter combination for the brake lining. A dynamometer test was carried out to validate the effect of optimization on brake noise mitigation.

Identification of a dynamic friction model for railway disc brakes

Braking forces occurring during emergency brake applications of passenger trains are generated by disc brake units. The acting friction forces depend on the frictional properties between disc and brake pad and are influenced by relative velocity, temperatures and normal pressure of the contacting surfaces. In this work a mathematical model is developed which aims to link these influencing variables to the instantaneous acting friction coefficient in order to include the characteristic behavior of friction forces in the calculation of longitudinal dynamics of railway vehicles. The model is identified by the use of data recorded on a full-scale dynamometer test rig and verified regarding the estimation of the brake distance.