: Isometric peak torque (PT) and rate of torque development (RTD) are important characteristics relevant to athletic performance. A novel device called the Dynamo Torque Analyzer calculates and ...displays real-time measurements of isometric PT and RTD. However, the ability of the Dynamo to provide valid and reliable isometric PT and RTD measurements similar to those of an isokinetic dynamometer remains unclear. This study aimed to compare the reliability and magnitude of isometric leg extension and flexion PT and RTD measurements between an isokinetic dynamometer and the Dynamo Torque Analyzer.
: Twenty healthy, recreationally-active adults (age = 22 ± 3 years; height = 169 ± 10 cm; mass = 71 ± 18 kg) performed three isometric leg extension and flexion maximal voluntary contractions on two different occasions, from which isometric PT and early (RTD100), late (RTD200), and maximum (Peak RTD) RTD characteristics were measured by an isokinetic dynamometer and the Dynamo.
: Isometric leg extension and flexion PT and RTD characteristics were highly consistent across sessions for both the isokinetic dynamometer and Dynamo devices, with intraclass correlation coefficients of 0.935-0.984 and standard errors of measurement expressed as a percentage of the mean of 4.93-14.46%. There were significant positive relationships between the isokinetic dynamometer and Dynamo for all PT and RTD characteristics (
≥ 0.994;
< 0.001). Moreover, no significant differences between devices were observed for these variables (
= 0.107-0.555).
: These findings suggest that the Dynamo Torque Analyzer may be a valid and reliable device for measuring isometric PT and RTD of the lower-body musculature.
This study illustrates a methodology for quantifying the uncertainties encountered in the measurement of tailpipe emissions and in the fuel consumption measurements for light-duty conventional ...vehicles tested on a four-wheel drive chassis dynamometer. The study leverages high-fidelity experimental data collected over three standard drive cycles, UDDS, HWY and US06, intended to simulate a wide range of operating conditions. A method is developed to estimate the measurement uncertainties in fuel consumption for a test cycle, which occur due to the accumulation of measurement uncertainties propagated through the system. The uncertainty determination model uses statistical analysis and standard propagation techniques to evaluate and combine the uncertainties introduced from various sources (including the vehicle, chassis dynamometer, driver, and instrumentation). The analysis also examines three different experimental methods for determining the fuel consumption: 1) carbon mass balance, 2) volumetric fuel scale and 3) gravimetric fuel scale, and takes into consideration the properties of the instrumentation used. The results show that the most significant influence on the determination of the emissions comes from the concentration measurement, and similarly the biggest impact on the total fuel consumption uncertainty comes from the uncertainty in the determination of the carbon dioxide mass, due to the large presence of this pollutant in the overall emissions. It was found that the fuel consumption uncertainties are in the range of ±1-2% for all three methods analyzed, with the lowest values being obtained for measurements performed using the gravimetric method for all three drive cycles considered.
In parallel with the significant reduction of the impact of vehicles on the environment, the development of modern propulsion systems that have less and less harmful impact, new pollutants are being ...identified on the vehicle. One of the such pollutants is the brakes, which wear out and lead to the formation of particles that are released into the air, i.e. generally into the environment. Investigation of the mechanism of particle formation during braking, and thus the brake wear is today becoming one of the important areas of research. The most common tests in this area are performed using initial brake dynamometers and pin-on-disc machines. An overview of the influence of some operation parameters (initial vehicle speed, braking pressure, and deceleration) that varies frequently during testing on an inertial brake dynamometer is performed in this paper. There are a number of tests and cycles that are applied during research, but they are not specifically prescribed for testing the particle formation during braking. The UNECE (United Nations Economic Commission for Europe) has included it in its plan and is in the development phase of introducing standardized cycles that will prescribe the braking cycle, the purpose of which will be to examine the formation of particles. This kind of review paper can be important for researchers who are engaged in this field, and the develop their own cycles or tests to examine the concentration or mass of particles formed during braking.
Patellofemoral pain (PFP) is a common knee complaint affecting diverse populations both acutely and chronically. Quadriceps muscle weakness is one possible aetiology, but current devices for ...measuring muscle strength (isokinetic dynamometer ID and hand-held dynamometers HHD) are frequently too expensive (e.g., ID) or lack reliability (e.g., HHD) for practitioners, especially in under-resourced settings. There is a need to evaluate a low-cost device to manage rehabilitation of people with PFP.
Isometric quadriceps strength of participants aged 18-35 years (total n = 33, control group n = 17 and PFP group n = 16) were evaluated on an isokinetic dynamometer and a commercially available strain gauge at baseline and after an 8-week non-standardised intervention.
The strain gauge showed high absolute and relative reliability (intraclass correlation coefficient = 0.89-0.99; typical error of measurement = 3.9-10.4%). Clinically meaningful difference scores (12.2-45 Nm) were greater than the typical error of measurement, implying sufficient sensitivity of the strain gauge to measure true changes in isometric quadricep strength. Strong to very strong correlations were evident between the strain gauge and isokinetic dynamometer torque measurements (r = 0.88-0.90, SEE = 0.05-0.07 Nm), but slope values (β = 0.65-0.77) indicated that torque from the strain gauge was lower than that obtained from the isokinetic dynamometer. An average systematic bias of 16.3-28.8 Nm was evident in favour of the isokinetic dynamometer, with no statistically significant between-group differences apparent between baseline and follow-up testing.
The present commercially available strain gauge is reliable and sensitive enough to detect clinically meaningful differences in quadriceps strength of both healthy individuals and those with PFP. However, the strain gauge lacks validity and therefore cannot replace isokinetic dynamometry. Given the low cost and excellent reliability, the strain gauge can be a valuable tool to assess quadriceps muscle deficits and track rehabilitation progress in people with PFP.
The current clinical gold standard for assessing isometric quadriceps muscle strength is an isokinetic dynamometer (IKD). However, in clinics without an IKD, clinicians default to using handheld ...dynamometers (HHD), which are less reliable and accurate than the IKD, particularly for large muscle groups. A novel device (ND) was developed that locks the weight stack of weight machines, and measures forces applied to the machine, turning this equipment into an isometric dynamometer. The objectives of this study were to characterize the test-retest reliability of the ND, determine the within-day and between-days inter-rater reliability and concurrent validity compared with that of the HHD, in healthy volunteers (HV) and individuals with knee osteoarthritis (OA) for measuring knee extensors isometric muscle force.
29 healthy (age = 28.4 ± 7.4 years) and 15 knee OA (age = 37.6 ± 13.4 years) participants completed three maximum force isometric strength testing trials on dominant side knee extensor muscles on three devices (ND, HHD, and IKD) in two separate sessions by two raters. The maximum force (Fmax) produced, and the force-time series were recorded. Reliability and validity were assessed using Intraclass Correlation Coefficient (ICC), Bland-Altman Plots, Pearson's r, and cross-correlations.
The ND demonstrated excellent test-retest reliability (ICC2,3 = 0.97). The within-day (ICC2,3 = 0.88) and between-day inter-rater reliability (ICC2,3 = 0.87) was good for HHD. The ND showed excellent within-day (ICC2,3 = 0.93) and good between-day (ICC2,3 = 0.89) inter-rater reliability. The Bland-Altman analysis revealed HHD systematic bias and underestimation of force particularly with quadriceps force values exceeding 450 N. Mean differences were found in maximum force between HHD vs. IKD (MDabs = 58 N, p < .001) but not the HHD vs. ND (MDabs = 24 N, p = .267) or ND vs. IKD (MDabs = 34 N, p = .051). The concurrent validity of Fmax (r = 0.81) and force-time curve correlation (0.96 ± 0.05) were the highest between the ND and IKD.
The ND's test-retest reliability and concurrent validity make it a potential strength assessment tool with utility in physical therapy and fitness settings for large muscle groups such as the knee extensors.
Equivocal findings exist on isokinetic and Nordic hamstring exercise testing of eccentric hamstring strength capacity. Here, we propose a critical comparison of the mechanical output of hamstring ...muscles as assessed with either a dynamometer (IKD) or a Nordic hamstring device (NHD). Twenty‐five volunteers (26 ± 3 years) took part in a counterbalanced repeated‐measures protocol on both devices. Eccentric peak torque, work, angle of peak torque, bilateral strength ratios, and electromyography activity of the biceps femoris long head, semitendinosus and gastrocnemius muscles were assessed. There was a very poor correlation in eccentric peak torque between the devices (r < 0.58), with a systematic and proportional bias toward lower torque values on the IKD (~28%) and a high typical error (~19%) in IKD and NHD measurements comparison. Furthermore, participants performed a higher total eccentric work on IKD, reached peak torques at greater knee extension angles, and showed a greater side‐to‐side strength difference compared to the Nordic hamstring exercise. Gastrocnemius muscle activity was lower during the Nordic hamstring exercise. Reliability was low for work on NHD and for angle of peak torque and bilateral strength ratios on either device. We conclude that the evaluation of eccentric knee flexor strength depends on the testing conditions and even under standardized procedures, the IKD and NHD measure a different trait. Both tests have limitations in terms of assessing strength differences within an individual, and measurements of the angle of peak torque or side‐to‐side differences in eccentric knee flexor strength revealed low reliability and should be considered with caution.
•The management strategy for a battery/supercapacitor/fuel cell system is proposed.•An optimal oxygen excess ratio control is proposed to maximize the net power.•The finite state machine method is ...proposed for power distribution.•The power capability and state-of-charge of energy devices are fully considered.•The fuel economy and dynamic property are analyzed.
In recent years, fuel cell vehicles have attracted attention for their zero emission and environmental friendship. The sole fuel cell system cannot satisfy the dramatical change of motor power demands. In addition, the power fluctuations will damage the fuel cell stacks and shorten the cycle life of fuel cells. Therefore fuel cell systems are always combined with other energy storage devices like batteries and supercapacitors to increase the power density of the power system and fulfill the load power demands. The management strategy of the hybrid propulsion system is a significant technique for the vehicular power system. In this work, a finite state machine based management strategy is first proposed for both the battery/fuel cell and battery/supercapacitor/fuel cell system. The power capabilities of the battery and supercapacitor have been considered as important parameters in the management strategy. Moreover, an optimal oxygen excess ratio control is presented to maximize the fuel cell output net power. To evaluate the performance of the fuel economy and dynamic property, both the simulations and experimental verifications with the real physical system are given, and the real driving cycle of urban dynamometer driving schedule is utilized. The experimental and simulated results indicate that the proposed method is able to guarantee the required power during most of the driving cycles.
•The paper analyzes the mechanism of dynamometer card.•A novel method, which is based on the curvature and the barycentric decomposition, is adopted to locate valve working positions of dynamometer ...cards at different working conditions.•Seven novel geometric features are extracted from dynamometer card according to qualitative and quantitative analysis.•The continuous hidden Markov model is first time applied in the field of sucker rod pumping diagnosis and the parameters of this model are optimized by the clonal selection algorithm to improve its classified performance.•Actual production data is adopted in simulation.
Down-hole operating condition diagnosis based on dynamometer card is a key subject for sucker rod pumping in oil extraction engineering. In this technology, feature extraction and diagnostic model are two indispensable elements. To accurately and automatically diagnose the operating condition by computer, a novel diagnostic method for sucker rod pumping is proposed. The first novel idea is to extract seven geometric features, which are obtained from dynamometer card using barycentric decomposition algorithm and valve working position. The second novel idea focuses on the use of continuous hidden Markov model (CHMM) to create classifiers for diagnosing the down-dole operating conditions and then clonal selection algorithm (CSA) is used to optimize the selection of initial parameters for CHMM. Finally, the proposed method is tested on an oil field dynamometer card set. Furthermore, this technique is compared with some other existing approaches. The simulation results demonstrate that the performance using the method proposed in this paper is satisfactory.
The belt-stabilized handheld dynamometer (HHD) has been used to assess the strength of knee- and hip-muscle groups. However, few researchers have examined its reliability and validity for assessing ...the strength of these muscles.
To evaluate the intra-examiner reliability of the belt-stabilized HHD and its validity and agreement with the isokinetic dynamometer for assessing the strength of knee- and hip-muscle groups.
Cross-sectional study.
University laboratory.
We evaluated 26 healthy participants (13 men, 13 women; age = 23.5 ± 2.8 years, height = 1.7 ± 0.1 m, mass = 68.6 ± 12.4 kg) in 2 sessions using the belt-stabilized HHD and an isokinetic dynamometer for maximum strength of the hip adductors, abductors, flexors, extensors, internal rotators, and external rotators and the knee flexors and extensors.
We used reliability values provided by the intraclass correlation coefficient (2,3), standard error of measurement (SEM and percentage SEM), and minimal detectable change; correlation values comparing the belt-stabilized HHD and the isokinetic instrument using the Pearson correlation coefficient (r); and the mean difference in values comparing the 2 instruments using the Bland-Altman method.
The intrarater HHD reliability was excellent for most measurements (range = 0.80-0.96; SEM = 1.3-5.3 kilograms of force or 4.8-18.9 Nm, percentage SEM = 7.0%-22.0%, minimal detectable change = 3.6-18.8 kilograms of force or 13.2-52.4 Nm) and was moderate only for bilateral knee flexion and left hip internal rotation (intraclass correlation coefficient 2,3 = 0.62-0.66 and 0.70, respectively). Correlation with the isokinetic dynamometer was moderate to high (r = 0.60-0.90), but the absolute values did not demonstrate concordance between results using the Bland-Altman method.
The belt-stabilized HHD measurements were reliable, and although they did not agree with those from the isokinetic dynamometer, the values were correlated for the hip- and knee-muscle groups.
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