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A major cause for the production of higher harmonic forces on the rotating system is the Misalignment between the shafts. This in-turn produces vibrations during the function of any turbine unit that can bring about untimely wear of bearings, loosening of disparate fasteners, and crash of the entire installation. Good efficiency can well be ensured by means of the proper alignment with the rotating elements’ motor axis. And it also makes sure that the motion and power transmission happens devoid of significant loss. The misalignment can well be found if there is a variation on the torque at the motor end. Along with it, the misalignment can well be detected by the torque variation. Here, utilizing the theoretical relationship betwixt the deflection factor and harmonic bending force generated on a formed test rig, the torque and power surge are simulated. Aimed at the data analysis, a statistical design centered upon the Responses Surface Methodology (RSM) is employed. The outcomes are plotted utilizing the Box-Behnken (BB) model to perform a simplified economical study that exhibits when a preventive in addition to predictive methodology can well be applied in the instance of misalignment.

Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure (SRP). It is desirable to control the attitude through propellant-free means. This paper proposes a new method for attitude control of solar sails: A boom consisting of “smart” structural material can be deformed by the piezoelectric actuator, and Solar Radiation Pressure torque will be generated due to shape variation of sail membrane caused by boom deformation. The method has the advantages of simple structure, small disturbance and small additional load, and is not limited by the size of the solar sail. The case of rendezvous with the Asteroid 2000 SG344 is used to verify the attitude control around the pitch and yaw axes.

In modern industrial production, rotating machinery plays an important role. The gears in this machinery adjust the speed and transmission of torque. Therefore, when the gear fails, it is very important to be able to diagnose the fault quickly and accurately. Gear vibration signals are often used in gear fault diagnosis, but the fault signal is often overwhelmed by noises. To enable the scientific and efficient detection of faults, this study proposes a gear fault diagnosis method based on variational modal decomposition (VMD) and wide+narrow visual field neural networks (WNVNNs), namely VMD-WNVNN. VMD-WNVNN consists of two stages. In the feature extraction stage, VMD and Pearson correlation coefficients are used to decompose and reconstruct the original data to obtain the features of these data in the frequency domain. In the classification stage, WNVNN is used to classify the data based on features. The final results of the gear fault diagnosis experiments show that this method not only has higher classification accuracy but also has higher classification stability than other recently proposed methods.

We address the motion planning problem for a robotic system whose configuration manifold contains a group of rotations. Our approach is applied to a free-floating space robot composed of a three-dimensional base (a spacecraft) and an anthropomorphic onboard manipulator. The robot is actuated by the torques exerted at the joints of the onboard manipulator. A coordinate-free representation of rotations is utilized. The Lagrangian formalism is employed in order to derive a dynamics model of the robot that takes the form of a control system defined on the group of rotations and the joint space of the onboard manipulator. Using the conservation of angular momentum of the robot, a Jacobian motion planning algorithm is designed relying on the Endogenous Configuration Space Approach. The performance of the algorithm is verified by computer simulations.

Enhancing the torsional capacity of reinforced concrete (RC) beams while maintaining reasonably economic and efficient cross-sections poses a practical challenge in the design of such elements. Thus, developing and testing economically viable reinforcing techniques for enhancing the torsional capacity of RC beams is a significant aspect. Among these techniques is the continuous spiral reinforcement system that has shown promising results in enhancing the torsional capacity of rectangular RC elements. In this study, the role of continuous rectangular spiral stirrups, as a transverse reinforcement with a controllable pitch (P) and inclination angle (θ), in enhancing the torsional behavior of rectangular solid and hollow RC beams has been investigated experimentally. The applied torque was directed to lock the spirals for all specimens. The experimental program of this investigation included testing of ten specimens of normal strength RC beams; two of which were solid with closed and spiral rectangular stirrups. While the rest of specimens were hollow specimens included one beam reinforced by closed stirrups and seven beams reinforced by rectangular spiral stirrups with different reinforcing ratios. Different variables were considered to develop a wide range of the beams’ reinforcing scenarios. This includes stirrups type (conventional closed stirrups and rectangular spiral stirrups), inclined stirrups ratio, pitch, inclination angle and finally the longitudinal reinforcement ratio. In addition, a three-dimensional finite element model using ANSYS-15.0 was developed to examine the capability of the model to capture the observed torsional behavior of the experimentally tested beams. The obtained results showed that using inclined spiral rectangular stirrups in reinforcing RC solid and hollow beams greatly enhanced the torsional capacity by about 16% and 18%, respectively compared to using the conventional closed stirrups. Moreover, the results showed that using that technique leads to higher twist- angles, more ductile failure and increased strain energy by about 27% and 16% for solid and hollow beams, respectively. Lastly, the comparison between the results obtained from numerical model and experimental results showed good agreement and thus the numerical model can be used to extend the experimental work for investigating different reinforcing schemes.

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Switched reluctance motors can be driven in a conventional or a modular way. In the conventional driving method, a number of stator coils are connected together and driven from one converter module. In the modular driving method, each stator coil is driven from one separate converter module. The conventional driving method provides better drive performance (i.e. efficiency, torque ripple, power density) but narrower speed range at rated torque and less fault tolerance-capability. The modular driving method provides wider speed range at rated torque and much better fault tolerance capability. Therefore, in low speed healthy operation, the conventional driving method is preferable while for high speed and faulty condition, the modular driving method should be used. In this paper, a converter topology that can be reconfigured to operate in conventional and modular driving ways is proposed and analysed. Using the proposed converter, the benefits of the conventional and the modular driving methods can be obtained by proper configuration of the converter. Also, a fault-tolerance strategy that results in symmetrical and high performance operation of the drive is proposed. The performance of the converter is assessed by simulations and experimental measurements.

Reactive stepping is one of the only strategies that can lead to successful stabilization following a large challenge to balance. Improving function of specific muscles associated with reactive stepping may improve features of reactive balance control. Accordingly, this study aimed to determine the relationship between lower limb muscle strength and explosive force with force plate-derived timing measures of reactive stepping. Nineteen young, healthy adults (27.6 ± 3.0 years of age; 10 women: 9 men) responded to 6 perturbations (~13-15% of body weight) using an anterior lean-and-release system (causing a forward fall), where they were instructed to recover balance in as few steps as possible. Foot-off, swing, and restabilization times were estimated from force plates. Peak isokinetic torque, isometric torque, and explosive force of the knee extensors/flexors and plantar/dorsiflexors were measured using isokinetic dynamometry. Correlations were run based on a priori hypotheses and corrected for the number of comparisons (Bonferroni) for each variable. Knee extensor explosive force was negatively correlated with swing time (r = −0.582, p = 0.009). Knee flexor peak isometric torque also showed a negative association with restabilization time (r = −0.459, p = 0.048), however this was not statistically significant after correcting for multiple comparisons. There was no significant relationship between foot-off time and knee or plantar flexor explosive force (p > 0.025). These findings suggest that there may be utility to identifying specific aspects of reactive step timing when studying the relationship between muscle strength and reactive balance control. Exercise training aimed at improving falls risk should consider targeting specific aspects of muscle strength depending on specific deficits in reactive stepping.

This study aimed to examine the acute effects of fast-paced walking on isometric peak torque and rate of torque development (RTD) in regular exercising and inactive older women. Ten regular exercising (67 ± 4 years) and 10 inactive (68 ± 4 years) older women performed three isometric knee extension contractions before and after a control condition (quiet resting) and an experimental condition of fast-paced walking for 6 min. Peak torque and early (RTD100), late (RTD200), and maximum (peak RTD) RTD measurements were obtained from each contraction. Results showed no significant changes in peak torque, peak RTD, or RTD200 after walking for either group (p > .050). A significant decrease in RTD100 was observed after walking for the inactive group (p = .005) but not for the regular exercisers (p = .909). These findings highlight the importance of physical activity and suggest that a task as simple as walking may impair the rapid strength capacities of inactive older women.

Statement of problem The mechanical behavior of the conical connection implant with different torque levels requires evaluation. Purpose The purpose of the finite element analysis study was to investigate the impact of abutment screw torque on the formation of microgaps at the implant-to-abutment interface of a conical connection under oblique loading. This is important because it is thought that bacteria can invade the internal implant space through the abutment-implant microgaps, causing peri-implantitis. Material and methods Three-dimensional finite element analyses of the conical implant-abutment connection were performed by using screw torques of 20 Ncm and 30 Ncm. Oblique loads from 10 N to 280 N were applied to the prosthesis placed on the implant. The maximum von Mises stress in the abutment screw, the microgap formation process, and the critical load for bridging the internal implant space were evaluated. Results The stresses in the abutment screw under oblique loading had limited sensitivity to the screw torque. However, the residual stress in the screw with a 30-Ncm torque was 35% higher than that with a 20-Ncm torque in the absence of an external load. The area in contact at the implant-to-abutment interface decreased with increasing load for both torque values. The critical load for bridging the internal implant space was 160 N for a screw torque of 20 Ncm and 220 N for a screw torque of 30 Ncm. The maximum gap size was approximately 470 μm with all the loads. Conclusions Increasing the screw torque can reduce the formation of microgaps at the implant-to-abutment interface. However, this will result in higher mean stress in the abutment screw, which may reduce its fatigue life and consequently that of the prosthesis. Further research is needed to evaluate the relationship between the abutment screw torque and microleakage in implant-supported restorations.

in order to enhance motor torque performance of existing two-phase 8/10 E-Core SRM, an improved modular permanent magnet (PM)-assisted Switched Reluctance Motor (SRM) structure is presented. Firstly, basic structure and operation principle of the proposed structure are introduced. To further evaluate performance improvement, effects of various parameters on the design such as inductance, flux-linkage, average torque and cogging torque are compressively investigated by finite element method (FEM) software subsequently. In the meantime, comparisons with other two-phase SRM structures are also performed including average torque, torque/PM volume, torque/ motor volume, torque/current, etc. Finally, a prototype is fabricated, and simulation and experimental results verify that the proposed design has high torque performance.

Tire and rubber track interchangeable chassis combines the advantages of tire and rubber track, which can greatly improve the maneuverability of military construction machinery. However, there is almost no effective calculation model for the real-time static steering torque. When the relative sliding speed is greater than 0.01 m/s, the influence of friction heating can not be ignored. An improved LuGre model is established to calculate the static real-time steering torque of tire and rubber track interchangeable chassis. Firstly, the friction heating model between rubber and ground is established. Combined with the influence of temperature on the dynamic performance of rubber material, the influence of friction heating on the stiffness and friction coefficient of rubber track is analyzed, and the improved LuGre friction model is established. The steering torque of tire and rubber track interchangeable chassis is affected by rubber material properties, steering speed, pavement type, and ambient temperature. Compared with the original LuGre model, the improved LuGre model captures the change in friction torque during multiple in-situ turns due to frictional heating. The error with the experimental data is small, which verifies the effectiveness of the improved LuGre model.

Focusing on the accurate size, direction and position of dynamic meshing impact, an innovative semi-finite element method (semi-FEM) forecasting model is proposed for spiral bevel gear transmission under both high speed and heavy load conditions. To distinguish with the traditional rotor dynamic analysis focusing on vibration effect for global system, a new dynamic loaded tooth contact analysis (DLTCA) focusing on loaded contact effect for local contact area is proposed for the geometric boundary forecasting. Where, DLTCA shows a systematically time-varying characteristics including the dynamic loaded contact pattern, pressure, transmission error. Considering tooth flank flexural behaviors, data-driven tooth flank simulation and finite element modeling is developed by using universal motion concept (UMC) machine settings. At each finite element in a local geometric boundary, the dynamic compatibility and equilibrium equations are established as a semi-FEM dynamic meshing impact forecasting model. Moreover, for a dynamic transmission system, a basic judgement criterion is firstly developed. Then, the improved simplex method is applied to solve the established model for the dynamic meshing impact size evaluations including transmission error, torque, angular velocity, and acceleration. Finally, numerical and test instances are provided to verify the proposed method.

The objective was to investigate the association between rate of torque development (RTD) and torque steadiness (TS) of the lower limb and the occurrence of prospective falls in community-dwelling older adults without falls in the previous year. One hundred older adults performed the tests to obtain the RTD and TS of the hip, knee, and ankle. New episodes of falls were monitored through telephone contact for a prospective period of 12 months. The association of RTD and TS with the occurrence of prospective falls was verified by multiple logistic regression adjusted for confounding variables. There was no association between RTD of hip, knee, and ankle and prospective falls. Only the TS at 50% of the peak torque of the hip flexors was associated with the occurrence of future falls (p = .023). Identifying modifiable risk factors for the first fall in older adults is essential for the development of adequate prevention programs.

A moving target tracking control problem for marching tank based on adaptive robust feedback control scheme is addressed. A series of preparations is needed for tank gun before shooting a target, the purpose of this paper is to design a control system to fulfill two requirements in this process: the turret-barrel system of tank needs to be adjusted from off-target position to command position and point to the moving target stably when there are strong uncertainties (modeling error, uncertain disturbance with unknown boundaries and road excitation) in the system. Considering the characteristic of coupled interaction, the first thing we do in this paper is to build a coupled analysis model of turret - barrel system with uncertainty term in state-space form. Second, an adaptive robust feedback control scheme is proposed by adding adaptive law to overcome the uncertainty. Third, multi-body dynamics software is used to establish the mechanical mechanism of the tank, and DC-motor module is established in SIMULINK environment, thus the target information and tracking error of the control system is collected and transferred, the gear-ball screw is derived directly by the output torque of the DC-motor module. Finally, the control system and the 3D model are combined together by means of RecurDyn/SIMULINK co-simulation, the turret-barrel system of tank can approximately track the moving target in a certain range. With the adaptive robust feedback control, the target action is completely followed when the target location is constantly changing.

PURPOSE To compare medial elbow stress during squatting throwing, standing throwing, and maximum effort throwing and to analyze its relationships with throwing variables and the hip joint internal rotation (IR) range of motion (ROM) in youth baseball catchers. METHODS Forty-five youth baseball catchers were recruited. Exclusion criteria included pain during throwing, history of surgery, or upper-extremity injuries within 12 months. Catchers performed 5 throws for each of the following throwing conditions: squatting throwing, standing throwing, and maximum effort throwing. Catchers were outfitted with a wearable sensor sleeve that recorded the medial elbow torque, arm speed, and shoulder rotation. Ball velocity was measured using a radar gun. RESULTS Final analysis included 42 catchers (mean age, 11.5 ± 1.2 years; mean catcher experience, 16.7 ± 10.3 months). The medial elbow torque was significantly greater during maximum effort throwing (19.0 ± 5.2 Nm) than during squatting throwing (14.3 ± 5.4 Nm) and standing throwing (15.7 ± 4.7 Nm) (both P < .001); there was no significant difference between squatting throwing and standing throwing. Multiple linear regression analysis showed that the ball velocity was significantly positively associated with the medial elbow torque during squatting throwing and standing throwing (P = .023 and P = .029, respectively). During squatting throwing, the hip IR ROM on the throwing side was significantly negatively associated with the medial elbow torque (P = .011). CONCLUSIONS The medial elbow torque during squatting throwing was equivalent to that during standing throwing. Increased medial elbow torque was associated with greater ball velocity during squatting throwing and standing throwing and with decreasing hip joint IR ROM on the throwing side during squatting throwing. Evaluation and stretching of the hip joint IR ROM on the throwing side may be important to decrease elbow stress during squatting throwing in youth baseball catchers. LEVEL OF EVIDENCE Level II, prospective comparative observational trial.

BACKGROUND: It is important for clinicians and researchers to perform dynamic postural control evaluation for predicting musculoskeletal conditions, injury prevention, and rehabilitation. OBJECTIVE: The purpose of this study was to investigate the relationship (1) between the eccentric strength of the knee extensors and star excursion balance test (SEBT), and (2) between the knee proprioception and SEBT. METHODS: Forty healthy young adults participated in this study. The eccentric peak torque (EPT) of the knee extensors, joint position sense, and force sense were measured. The participants also performed SEBT. Pearson’s product-moment correlation and multiple linear regression analysis were used to determine the relationship between the variables and SEBT. RESULTS: The posteromedial direction of the SEBT was positively and strongly correlated with EPT (r= 0.74, P< 0.01). The anterior and posterolateral directions were positively and moderately correlated with EPT (r= 0.46, P< 0.01, and r= 0.69, P< 0.01, respectively.). However, knee proprioception was not correlated with all the directions of SEBT (P> 0.05). According to the results of multiple linear regression analysis, EPT of the knee extensors significantly predicted SEBT reach distances. CONCLUSION: The eccentric strength of the knee extensors seems to be an essential factor in dynamic postural control. However, the knee proprioception did not show a significant correlation with SEBT.

In this paper, two novel dual stator machines with different biased permanent magnet (PM) configurations are developed and comparatively studied. For the proposed machines, the PMs are only located in the inner stator, but with different configurations, i.e., surface-mounted PM (SPM) and interior PM (IPM), respectively. The machine topologies and operating principle are introduced first. Then, the electromagnetic characteristics, including open-circuit performance, torque characteristics, field weakening capability, loss and efficiency are comprehensively analyzed and compared by finite element method (FEM). The experimental validation are conducted to verify the FEM analyses.

This article identifies the parameters of an induction machine using limited and nonintrusive observations of available input voltages, stator currents, and the rotor speed. Parameter extraction is formulated as a nonconvex estimation problem, which is then relaxed to a convex conic optimization problem. While the resulting relaxation could exhibit a satisfactory performance, there might be cases where the solution of convex relaxation fails to satisfy the dynamic equations of the machine. This is remedied through a local search approach initiated using the solution obtained from the relaxed problem. The proposed method is experimentally verified on a squirrel-cage induction machine with missing measured data. Using the measured signals as the benchmark, time-domain transients produced by the parameters estimated using the proposed method show almost 20% better match compared to time-domain transients produced by the parameters obtained via conventional testing.

In this paper, the drivetrain identification problem of a horizontal axis gear-driven wind turbine has been considered. The identification problem leads to a precise model of the drivetrain of the wind turbines which plays a key role in the production and transmission of electrical energy. This process consists of two stages: First, offline identification which needs the input–output data from the drivetrain system. These data are obtained from the FAST code. FAST (Fatigue, Aerodynamics, Structures, and Turbulence) is a valid aeroelastic code in the simulation aeroelastic field of offshore and onshore wind turbines. In region 2 (wind velocity is between the cut-in and rated velocities), the generator torque is input, and rotor speed is output. It is supposed that the wind velocity is neglected in the identification process (the identification process is not considered in the presence of wind or done in the low wind velocities bellower than the cut-in wind velocity). In the second stage, after completion of the offline identification process, the drivetrain model of the wind turbine is obtained but the aerodynamic torque in the real performance of the wind turbine is still unknown. In this stage, to estimate the aerodynamic torque, high order sliding mode estimator is used and the unknown states are estimated by using the Extended Kalman Filter (EKF)

In this paper, a novel winding switching control strategy is proposed to extend the speed range of a consequent-pole ferrite-PM hybrid-excited machine (CPFPM-HEM) for electric vehicle application. The key is that in low-speed range, the AC armature winding and DC field winding are connected in series to achieve large starting torque, while in high-speed range, DC field winding are injected with adjustable DC currents to realize variable speed constant voltage of AC armature winding. Furthermore, consequent-pole rotor is used to reduce the usage of the permanent magnet (PM). In the meantime, ferrite PMs are used to replace rare-earth PMs to reduce the cost with the shortage of rare earth resources. In this paper, the machine configuration, operation principle with dual excitation sources, flux modulation principle and winding switching strategy are illustrated in detail. Then, the electromagnetic performance of the CPFPM-HEM in different speed ranges is investigated. Finally, the speed range extension with winding switching strategy is verified by the Maxwell/Simplorer co-simulation.

Measurement of muscle strength is fundamental for the management of patients with myotonic dystrophy type 1 (DM1). Nevertheless, guidance on this topic is somewhat limited due to heterogeneous outcome measures used. This systematic literature review aimed to summarise the most frequent outcome measures to assess muscle strength in patients with DM1. We searched on Pubmed, Web of Science and Embase databases. Observational studies using measures of muscle strength assessment in adult patients with DM1 were included. From a total of 80 included studies, 24 measured cardiac, 45 skeletal and 23 respiratory muscle strength. The most common method and outcome measures used to assess cardiac muscle strength were echocardiography and ejection fraction, for skeletal muscle strength were quantitative muscle test, manual muscle test and maximum isometric torque and medical research council and for respiratory muscle strength were manometry and maximal inspiratory and expiratory pressure. We successfully gathered the more consensual methods and measures to evaluate muscle strength in future clinical studies, particularly to test muscle strength response to treatments in patients with DM1. Future consensus on a set of measures to evaluate muscle strength (core outcome set), is important for these patients.

By means of numerical models for torsional behavior of bundle conductors under distributed torque, parameter study of torsional behavior under various structural parameters, including conductor type, bundle number, bundle spacing, span length, height difference, initial tension in sub-conductors, spacer number and arrangement of spacers, is carried out. With the over twenty thousand numerically simulated samples a dataset is set up. A surrogate model for the prediction of torsional behavior of bundle conductor lines is constructed by means of the BP neural network, in which the structural parameters are set as the input variables and the collapse torque and torsional stiffness the output. The dataset is divided into two subsets, the training dataset and the testing one. High prediction precision of the surrogate model is achieved through training with the training dataset and verified by the testing dataset. Combining the surrogate model and the particle swarm optimization (PSO) method, optimizations of spacer arrangement to obtain maximum collapse torque and torsional stiffness of bundle conductor lines are carried out.

This article presents an improved model-based predictive current control for a surface permanent magnet synchronous generator (SPMSG), where the dynamic response time can be adjusted according to the characteristics of the application and that can operate in the overmodulation region. Moreover, the steady-state errors typically observed in other model predictive controls (MPCs) due to the uncertainties of the system and errors in the parameter values are removed in the proposed MPC. The proposed MPC was tested for the nED100 wind turbine of Norvento in MATLAB/Simulink environment. Besides, it was assessed in an 8.7 kW SPMSG laboratory prototype. The simulation and experimental results indicate that the proposed MPC works properly in an overmodulation region and the desired dynamic response time is achieved whereas the switching frequency is constant.

This paper proposes a novel differential kinematics of elastic tendons for tendon-driven manipulators where tendons transmit actuator force/torque to remote links via a train of pulleys. The local variability of tension and longitudinal speed in each tendon is carefully investigated in terms of the rest lengths of the virtually partitioned tendon segments along the tendon. A significant attention is paid to building a proper friction-tension mechanic model between the pulleys and tendons to identify the no-slip points that are important to be used as kinematic constraints. The kinematic relations of tendon are obtained for two possible types of tendon-pulley transmission, i.e., free-free ended and fixed-free ended types, and then a complete kinematics of tendon is formulated by augmenting all the kinematic relations existing in the entire system. Simulation and experimental results are provided to validate the proposed kinematics of tendon by comparing with a previous simple spring model where the tension was determined by the relative positions of consecutive pulleys.

Flux switching motors (FSMs) with conventional stator slots have relatively low copper slot filling factor. In this paper a new octane modular stator with pentagon shape slot electrically excited FSM that has comparatively higher copper slot filling factor is analyzed analytically to reduce the computational complexity, high computational time and high drive storage. The analytical results of the proposed EEFSM are validated via finite element method. Furthermore, initial design is optimized to improve the electromagnetic performance, finally prototype is fabricated and tested experimentally. There is good agreement among the analytical, FEA and experimental results with variation of 3 to 5%. The average torque of the optimized design has improved 30%, cogging torque suppressed 36%, and torque ripples reduced 38%, which has improved the performance of EEFSM in terms of low acoustic noise, low vibration and longer motor lifetime. The proposed octane modular stator can be easily unfolded for windings maintenance, coils placement and motor transportation in case of large size applications.

Objective We reviewed and appraised the existing evidence of in vivo manifestations of residual force enhancement in human skeletal muscles and assessed, through a meta-analysis, the effect of an immediate history of eccentric contraction on the subsequent torque capacity of voluntary and electrically evoked muscle contractions. Methods Our search was conducted from database inception to May 2020. Descriptive information was extracted from, and quality was assessed for, 45 studies. Meta-analyses and metaregressions were used to analyze residual torque enhancement and its dependence on the angular amplitude of the preceding eccentric contraction. Results Procedures varied across studies with regards to muscle group tested, angular stretch amplitude, randomization of contractions, time window analyzed, and verbal command. Torque capacity in isometric (constant muscle tendon unit length and joint angle) contractions preceded by an eccentric contraction was typically greater compared to purely isometric contractions, and this effect was greater for electrically evoked muscle contractions than voluntary contractions. Residual torque enhancement differed across muscle groups for the voluntary contractions, with a significant enhancement in torque observed for the adductor pollicis, ankle dorsiflexors, ankle plantar flexors, and knee extensors, but not for the elbow and knee flexors. Meta-regressions revealed that the angular amplitude of the eccentric contraction (normalized to the respective joint's full range of motion) was not associated with the residual torque enhancement observed. Conclusion There is evidence of residual torque enhancement for most, but not all, muscle groups, and residual torque enhancement is greater for electrically evoked than for voluntary contractions. Contrary to our hypothesis, and contrary to generally accepted findings on isolated muscle preparations, residual torque enhancement in voluntary and electrically evoked contractions does not seem to depend on the angular amplitude of the preceding eccentric contraction.

Introduction The observed variability in the effects of transcranial direct current stimulation (tDCS) is influenced by the amount of current reaching the targeted region-of-interest (ROI). Age and sex might affect current density at target ROI due to their impact on cortical anatomy. The present tDCS simulation study investigates the effects of cortical anatomical parameters (volumes, dimension, and torque) on simulated tDCS current density in healthy young, middle-aged, and older males and females. Methodology Individualized head models from 240 subjects (120 males, 18–87 years of age) were used to identify the estimated current density (2 mA current intensity, 25 cm2 electrode) from two simulated tDCS montages (CP5_CZ and F3_FP2) targeting the inferior parietal lobule (IPL) and middle frontal gyrus (MFG), respectively. Cortical parameters including segmented brain volumes (cerebrospinal fluid [CSF], grey and white matter), cerebral-dimensions ( length / width & length / height ) and brain-torque (front and back shift, petalia, and bending) were measured using the magnetic resonance images (MRIs) from each subject. The present study estimated sex differences in current density at these target ROIs mediated by these cortical parameters within each age group. Results For both tDCS montages, females in the older age group received higher current density than their male counterparts at the target ROIs. No sex differences were observed in the middle-aged group. Males in the younger age group had a higher current density than females, only for the parietal montage. Across all age groups, CSF, and grey matter volumes significantly predicted the current intensity estimated at the target sites. In the older age group only, brain-torque was a significant mediator of the sex difference. Conclusions Our findings demonstrate the presence of sex differences in the simulated tDCS current density, however this pattern differed across age groups and stimulation locations. Future studies should consider influence of age and sex on individual cortical anatomy and tailor tDCS stimulation parameters accordingly.

The utilization of renewable energy harvesting equipment is one of the methods to reduce the level of environmental pollution risks to the world. Water and wind are considered as environmental potential resources which have become attractive features of urban utilization through different wind and hydrokinetic turbine design technology. While no large-scale Savonius turbines have been developed yet, one of the popular designs is the small-scale rotor, which utilizes a drag-based vertical axis. The advantages of this type of rotor are easy to design, inexpensive, perform well at low speed, and have the capacity to turn independently to the wind-water direction flow. However, through a number of investigations on the performance the Savonius rotor, it was found to suffer from inefficient operation and a large amount of negative torques produced by the returning blade. To resolve the limitations in performance of the Savonius turbine, many optimization techniques and assessments have been conducted on different rotor types. The studies presented and discussed the challenges and changes in variations of rotor design parameters and their significant influence on rotor performance. In order to increase the unit's output without extra cost, improving variable parameters and reducing torques were accomplished in the negative direction while decreasing maintenance cost. Hence, the data collected were classified based on geometric and installation aspect parameters, and different optimization studies were summarized based on several influencing parameters.

In this paper, the simplified electromagnetic force/torque model and coupled orbit-attitude dynamics modeling in spacecraft electromagnetic docking are investigated, and an improved sliding mode control scheme based on planned trajectory is proposed. In this scenario, the docking two spacecraft are equipped with four energized solenoids with iron cores fixed in the body frame, and small-angle hypothesis is used to derive the simplified electromagnetic force/torque model, based on which the coupled orbit-attitude dynamics equation is established. With trajectory planning of relative orbit and attitude, where the tracking process of coupled orbit-attitude is divided into three successive parts with predefined time using three characteristic time instants, a sliding mode control strategy is proposed to solve the tracking problem. Simulation results illustrate the simplification rationality of electromagnetic force/torque model, and the good tracking performance of coupled orbit-attitude tracking controller at predefined time.

In the history of solar sail research, numerous methods have been proposed to control the spacecraft attitude. Different in detailed operations, almost all of them rely on solar radiation pressure torques generated by manipulating the offset between the center of mass and the center of pressure. In this paper, a solar sail attitude control method that does not rely on solar radiation pressure is proposed. The method is demonstrated for the case of a quad sail that consists of 4 separate triangular wings. Each wing is able to pitch along its own longitudinal axis. During the pitch, according to the conservation of angular momentum, an internal torque exerted on the remaining part of the sail would be generated. Analysis is conducted regarding the kinematic behavior of the solar sail attitude during wings pitching, based on which two different attitude maneuver strategies are proposed. On one hand, the proposed attitude control method is a new one that no longer relies on the solar radiation pressure. On the other hand, this research also serves as a supplement to some of the existing research, in which relative motion between parts of the sail are involved but the internal torque effect is either neglected or treated as disturbance.

Background: Accurate quantification of voluntary activation is important for understanding the extent of quadriceps dysfunction in individuals with anterior cruciate ligament reconstruction (ACLR). Voluntary activation has been quantified using both percent activation derived from the interpolated twitch technique and central activation ratio (CAR) derived from the burst superimposition technique, as well as by using different types of electrical stimulators and pulse train conditions. However, it is unclear how these parameters affect voluntary activation estimates in individuals with ACLR. This study was performed to fill this important knowledge gap in the anterior cruciate ligament literature. Methods: Quadriceps strength and voluntary activation were examined in 18 ACLR participants (12 quadriceps/patellar tendon graft, 6 hamstring tendon graft; time since ACLR: 1.06 ± 0.82 years, mean ± SD) at 90° of knee flexion using 2 stimulators (Digitimer and Grass) and pulse train conditions (3-pulse and 10-pulse). Voluntary activation was quantified by calculating both CAR and percent activation. Results: Results indicated that voluntary activation was significantly overestimated by CAR when compared with percent activation (p < 0.001). Voluntary activation estimates were not affected by pulse train conditions when using percent activation; however, 3-pulse stimuli resulted in greater overestimation than 10-pulse stimuli when using CAR (p = 0.003). Voluntary activation did not differ between stimulators (p > 0.05); however, the Digitimer evoked greater torque at rest than the Grass (p < 0.001). Conclusion: These results indicate that percent activation derived from the interpolated twitch technique provides superior estimates of voluntary activation than CAR derived from burst superimposition and is less affected by pulse train conditions or stimulators in individuals with ACLR.

With the increasing requirements for miniaturization and high braking torque, it is now necessary to analyze the thermal characteristics to the same extent as the electromagnetic design for eddy current brakes. However, due to the lack of suitable convection heat transfer correlations for axial flux eddy current brakes, it brings difficulties to designers. To solve this problem, the correlations for an axial flux permanent magnet (PM) eddy current brake are derived using the computational fluid dynamics (CFD) and the least square method. The proposed correlations considered the changes in design parameters and temperatures of the eddy current brake, and the accuracy is verified by the CFD. Subsequently, convective heat transfer coefficients calculated through the correlations are assigned to a thermal network model of the eddy current brake, and the thermal network model is verified by experimental tests. The results show that the thermal network model can accurately predict temperatures of the eddy current brake. Since the time required to calculate convective heat transfer coefficients through the correlations is significantly less than that required through CFD, and the variation of the geometrical parameters and temperatures can be considered, these correlations are very suitable for use in the optimization process.

Since the established wind farms (WFs) have a strong demand for reducing maintenance costs, the fatigue load suppression of wind turbines (WTs) has become more important in WFs. To suppress the fatigue load during operation, the traditional schemes are tried by allocating the optimized power setting value to each WT, which does not directly point to the key operating parameters that affect fatigue. In response to this, an advanced WT control model with two-degree-of-freedom (2Dof) is applied in this paper to ensure that the generator torque and pitch angle (two key parameters affecting fatigue load) of each WT are directly controlled. In order to achieve effective control of the above two parameters in multiple WTs, a hierarchical distributed control architecture with dynamic-local-reference is proposed to jointly optimize the above two configurable parameters at both the WT and WF levels. Several cases are compared to verify the proposed method, and simulation results show that the proposed 2Dof control model for WT and distributed control framework for WF can significantly reduce the fatigue load of each WT while completing the active power command of the whole WF.

A challenge in horizontal-axis wind turbines is power regulation and transient rejection during the transition between their three operational regions. In particular, the wind’s uncertain nature can lead to undesired electromechanical effects, which in turn decrease power generation efficiency and, in extreme cases, could also be the cause of irreparable damage to the system itself. This letter presents a robust controller that allows the fraction of captured wind energy to be kept while maintaining the transient loads in safe values and preserves electricity generation inside its nominal values in Region III. A linear plus a non-homogeneous quasi-continuous second-order sliding-mode control is proposed to supply energy into the system to maintain the desired power and reject the undesired electromechanical effects. The non-homogeneous controller improves the efficiency of the power generation by reducing the effects of chattering and allowing faster convergence.

BACKGROUND Increased sagittal-plane trunk tilt is thought to increase drive in the anterior direction toward home plate, transferring energy from the trunk to the distal upper extremity, ultimately generating greater ball velocity. Increased sagittal trunk tilt has also been implicated in the risk of upper-extremity joint loading in baseball pitchers by way of elbow varus torque (EVT), a metric previously associated with elbow injury in professional pitchers. The purposes of this study were (1) to compare sagittal trunk tilt positioning between high school and professional pitchers throughout the pitch and (2) to identify the potential associations between sagittal-plane trunk tilt, ball velocity, and EVT for both cohorts. METHODS Professional and high school pitchers were instructed to throw fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Sagittal trunk tilt motion throughout the pitching motion was compared between cohorts from maximum knee height to maximum shoulder internal rotation. To assess the effects of sagittal-plane trunk tilt on ball velocity and EVT, linear mixed-effect models were created. RESULTS Professional pitchers (n = 100, 882 pitches) achieved greater sagittal trunk tilt than high school pitchers (n = 57, 519 pitches) during early portions of the pitching motion, including maximum positive sagittal trunk tilt (46.6° ± 8.3° vs. 43.6° ± 10.2°, P = .042). Professional pitchers also had greater sagittal trunk tilt excursion throughout the pitch motion (68.0° ± 11.4° vs. 62.5° ± 11.0°, P = .004). For every 10° increase in sagittal trunk tilt at ball release for professional pitchers, ball velocity increased by 0.36 m/s (B = 0.036 and β = 0.194, P < .001) or 0.9% average ball velocity whereas EVT increased by 0.14% body weight × body height (B = 0.014 and β = 0.159, P < .001) or 2.9% average normalized EVT. For every 10° increase in sagittal trunk tilt at ball release for high school pitchers, ball velocity increased by 0.34 m/s (B = 0.097 and β = 0.025, P = .025) or 1.1% average ball velocity whereas EVT increased by 0.07% body weight × body height (B = 0.007 and β = 0.086, P = .016) or 1.7% average normalized EVT. CONCLUSION Increased positive sagittal-plane trunk tilt was significantly associated with greater ball velocity and increased EVT for both professional and high school pitchers. Peak EVT estimates were consistently more pronounced than ball velocity benefits for both populations, suggesting that no specific time point may provide a ball velocity benefit while concomitantly minimizing EVT. Both professional and high school pitchers should consider this trade-off, which may influence injury risk, when engaging in higher degrees of positive sagittal-plane trunk tilt.

In this study is to evaluate the mechanical performance and the environmental impact of a diesel engine operating with conventional diesel, diesel/biodiesel blends (B5) and additive (B5A) with the objective to analyze the effect of the use of additives in biodiesel blends on torque, power and opacity. For the investigation, mechanical and environmental tests are performed using updated and calibrated automotive diagnostic equipment with the application of each fuels in two vehicles at 2220 mamsl, and finally the results are presented at through statistical analysis software. The results obtained show that the best biodiesel blend is B5A, with which a non-significant reduction of 0.4% in torque and 0.26% of power is obtained, in addition to a decrease of 58% in opacity compared to the values obtained with conventional diesel. The properties of the additive make it possible to reduce the disadvantages that biodiesel presents on the mechanical performance of the vehicle, increasing the power value by 1.67% and the torque 1.26% with an additional reduction of 20.2% to the opacity values, compared to those obtained with B5 blend. With the results obtained, it is concluded that the organic-metallic catalytic effects of the additive allow a more complete and efficient combustion process to be obtained, increasing engine performance and reducing the quantity of polluting gas emissions.

Simultaneous and proportional control (SPC) using surface electromyography (sEMG) signals has become a prevailing solution for the intuitive control of prosthesis and human–robot interaction. However, only time and frequency domain features are generally involved in conventional SPC algorithms, ignoring the globally spatial information across channels. In this article, we presented an instantaneous sEMG-image-based model for continuous estimation on multiple degrees of freedom wrist torques. Specifically, a convolutional neural network was used to extract features from sEMG-images, and then to estimate wrist torques. The results demonstrated that the sEMG-image-based model outperformed three conventional regression methods and a deep-learning-based method with superior performance on estimation accuracy and smoothness. Furthermore, we found a strong linear correlation between the first two principal components of extracted features and the recorded wrist torques, validating the effectiveness of the proposed approach. The outcomes open up a new perspective for SPC and potentially enhance the performance of myoelectric control in practical application.

A significant part of an automobile is the gear box (tractor) casing. The primary objective of using the Gearbox casing is to embrace and allow the transmission of the Gearbox. The Gearbox is a mechanism that regulates speed or torque between the flywheel and the differential. The main shaft and lay shaft with gears equipped embraces the gear box. This paper deals with the modeling and study as an alternative material of the gear box casing for a tractor with E-Glass. Through the development of the simulation software platform ANSYS, it is analyzed statically with different design parameters such as web thickness, gear box housing depth and gear box housing thickness. In order to determine the stress produced and deformation degree, the gear box with traditional Grey cast iron is analyzed; it is then compared with the housing of the E-Glass Gear box. The outcome will be studied and evaluated after study, various combinations of design parameters were used to achieve the design that minimum output in failure at higher load s has better deformation characteristics. Finally, in order to design the gear box housing, an optimized design parameter is obtained.[1]

The variability and uncertainty of wind power generation pose severe challenges in balancing supply and demand in real time. To overcome this challenge, one promising solution is to exploit the self-regulation capabilities of wind turbines (WTs) and operate them as “semi-dispatchable” resources. In this article, the rotor speed control and pitch angle control are utilized simultaneously to regulate wind power output. It should be noted that changing the operating point of a WT affects the forces and moments it experienced. To increase the life span of WTs and decrease maintenance costs, an optimization problem that aims to track the dispatch command while minimize fatigue loads is formulated. Due to the nonlinearity and nonconvexity of the WT model and load estimation model, the resulting optimization problem cannot be solved online. To address this issue, an intelligent learning based method is designed. Extensive case studies are conducted, and simulation results demonstrate that the proposed method can effectively exploit the regulation capability of WTs to trace the given dispatch command while also reducing the shaft torque and thrust-induced loads.

Introduction: Limited evidence has been shown on ways to optimize the mechanical design of machines in order to minimize knee loads. Objective: This study compared six computer simulated models of open kinetic knee extension exercises for patellofemoral pressure and tibiofemoral forces. Methods: A musculoskeletal model of the lower limb was developed using six different cam radius to change resistive forces. A default machine, a constant cam radius, a torque-angle model, a free-weight model and two optimized models were simulated. Optimized models reduced cam radius at target knee flexion angles to minimize knee forces. Cam radius, human force, tibiofemoral compressive and shear force, and patellofemoral pressure were compared for the six models using data from five knee flexion angles. Results: Large reductions in cam radius comparing the free-weight model to other models (73-180%) were limited to the large human force for the constant cam model to other models (9-36%). Larger human force (13 -36%) was estimated to perform knee extension using a constant cam radius compared other models without large effects in knee joint forces. Conclusion: Changes in cam design effected human without a potential impact in knee loads. Resumo Introdução: As evidências são limitadas quanto às formas de otimização do arranjo mecânico das máquinas a fim de minimizar as forças na articulação do joelho. Objetivo: O presente estudo comparou seis modelos de extensão de joelhos realizados em cadeia cinética aberta sob a pressão aplicada nas articulações patelofemoral e tibiofemoral. Métodos: Um modelo do sistema musculo-esquelético do membro inferior foi desenvolvido utilizando seis desenhos de roldana com o objetivo de alterar as forças resistivas. Uma máquina referência foi utilizada, uma com uma roldana concêntrica, um modelo baseado na relação torque-ângulo dos extensores do joelho, um modelo de peso livre e dois modelos otimizando a aplicação de cargas foram simulados. A otimização foi aplicada visando reduzir o raio da roldana excêntrica e minimizar as forças aplicadas no joelho. O raio da roldana, a força produzida pelo executante, as forças compressivas e de cisalhamento nas articulações tibiofemoral e a pressão na articulação patelofemoral foram comparadas para os seis modelos de máquina utilizando cinco ângulos de flexão do joelho. Resultados: Reduções no raio da roldana foram observadas comparando o modelo de peso livre com os demais modelos (73-180%). Maior força produzida foi observada para o modelo de roldana constante comparado aos demais modelos (9-36%). Maior força produzida foi estimada para realizar a extensão do joelho utilizando a roldana constante comparada com os demais modelos (13-36%) sem efeitos sobre as forças no joelho. Conclusão: O arranjo mecânico das máquinas alterou a força produzida pelo executante sem afetar as forças aplicadas no joelho.

Investigates the performance of induction machines as a function of the power system’s fundamental and harmonic voltages/currents. It includes sinusoidal model of induction machine, time and space harmonics, forward- and backward-rotating harmonic magnetic fields, and magnetic field- and torque calculations based on the finite-difference method. The steady-state stability of rotating machines is reviewed, and the extension of the variable-speed range is obtained through compensation of flux weakening. Fundamental, integer, inter-, fractional and sub-harmonic torque characteristics of three-phase induction machines are analysed. The interaction of space and time harmonics, voltage-stress winding failures, classification and available harmonic models of induction machines as well as discussions of rotor eccentricity are provided. 14 application examples with solutions and 14 application-oriented problems are listed.

ObjectivesThis study aimed to investigate short-interval intracortical inhibition (SICI) and muscle function in the Triceps surae of runners with mid-portion Achilles tendinopathy (AT).MethodsRunners with (n=11) and without (n=13) AT were recruited. Plantar flexor isometric peak torque and rate of torque development (RTD) were measured using an isokinetic dynamometer. Triceps surae endurance was measured as single leg heel raise (SLHR) to failure test. SICI was assessed using paired-pulse transcranial magnetic stimulation during a sustained contraction at 10% of plantar flexor isometric peak torque.ResultsTriceps surae SICI was 14.3% (95%CI: -2.1 to 26.4) higher in AT than control group (57.9%, 95%CI: 36.2, to 79.6; and 43.6% 95%CI:16.2 to 71.1; p=0.032) irrespective of the tested muscle. AT performed 16 (95%CI: 7.9 to 23.3, pPerspectiveOur data suggest greater intracortical inhibition for the Triceps surae muscles for the AT group accompanied by reduced SLHR endurance, without deficits in isometric peak torque or RTD. The increased SICI observed in the AT group could be negatively influencing Triceps surae endurance; thus, rehabilitation aiming to reduce intracortical inhibition should be considered to improve patient outcomes. Furthermore, SLHR is a useful clinical tool to assess plantar flexor function in AT patients.

Six-axis force/torque sensors are transducers capable of measuring three dimensions of force and three dimensions of torque, and have a wide range of applications in robotic systems. The sensing principle behind the greatest majority of these is based on detecting strains in an elastic structure, and there are multiple modalities for strain measurement, including resistive strain gauge, piezoelectric, capacitive, and optoelectronic techniques. Developed sensors can be evaluated based on a range of parameters, including decoupling error, nonlinearity error, and measurement isotropy, where the primary design challenge is to maximise the allowable sensing range while minimising measurement errors. This literature review describes the state of the art of the field, and includes all relevant research associated with the search term "six-axis force/torque sensor" spanning 2015 - June 2021. The published literature for each sensing technique is summarised and evaluated, and a generalised sensor selection framework is proposed to assist the reader with the selection procedure for a state of the art sensor. In the period considered, there have been no significant improvements with the sensors documented in terms of measurement errors. Researchers have instead focused on features such as fault tolerance, alternative sensing techniques, cost reduction, and miniaturisation. These trends are expected to continue, and moving forward, the most significant challenge in the field is expected to be the lowering of manufacturing costs, as trends indicate measurement performance has reached maturity.

The modulation bandwidth (fBW) is a critical figure-of-merit for wireless communication applications of spin torque nano-oscillators (STNOs) as it determines the maximum data rate. Although both theory and previous experiments have shown that fBW in STNOs is governed by the amplitude relaxation frequency fp, we here demonstrate, using single-shot time-resolved measurements of a magnetic tunnel junction based STNO, that it can be many times larger under strong modulation. The behavior is qualitatively reproduced in macrospin simulations. Our results show that fBW of STNOs is not as limiting a factor for future wireless applications as previously believed.

Model predictive control has been considered as a potential alternative method in electrical drives. High reliable predictive model design is a research hotspot. To further improve the performance, a robust continuous model predictive speed and current control for PMSM with an adaptive integral sliding-mode approach are put forward. The prediction model is directly derived from the integral slinging-mode surface. By using the self-regulation method control and the amplitude of the sliding-mode function, an adaptive integral sliding-mode predictive control (AISMPC) is designed. The proposed strategy solves the chattering problem of sliding-mode control and improves the dynamics of the system. AISMPC has been carried out on a digital signal processing hardware system. The experimental results validate the excellent tracking performance of the proposed strategy.

This article presents the optimal design from the electromagnetic and structural point of view of a fault-tolerant modular outer rotor synchronous reluctance machine, a not previously constructed topology. Two new topologies with the rotor in modular construction, one with each pole of the rotor considered as a separate module and a segmented one where each rib of a module can be considered as independent, are compared with a classic structure. The electromagnetic analysis is carried out using FLUX 2D software. The main studied parameters are electromagnetic torque, torque ripple content, saliency ratio, and power factor. In order to optimize the power factor of the machine, a cosimulation procedure is carried out for each structure, by employing a MATLAB and FLUX 2D coupling. Based on the obtained performances, the best topology is selected. Furthermore, a mechanical analysis is performed to determine if the new proposed rotor meets the structural integrity at rated speed and to establish the maximum speed value that can be attained such that the structural failure of the rotor is prevented. A modular outer rotor synchronous reluctance machine is designed and built. Experimental results of testing the prototype are given to confirm the validity of the proposed machine.

Haptic guidance in a shared steering assistance system has drawn significant attention in intelligent vehicle fields, owing to its mutual communication ability for vehicle control. By exerting continuous torque on the steering wheel, both the driver and support system can share lateral control of the vehicle. However, current haptic guidance steering systems demonstrate some deficiencies in assisting lane changing. This study explored a new steering interaction method, including the design and evaluation of an intention-based haptic shared steering system. Such an intention-based method can support both lane keeping and lane changing assistance, by detecting a driver's lane change intention. By using a deep learning-based method to model a driver's decision timing regarding lane crossing, an adaptive gain control method was proposed for realizing a steering control system. An intention consistency method was proposed to detect whether the driver and the system were acting towards the same target trajectories and to accurately capture the driver's intention. A driving simulator experiment was conducted to test the system performance. Participants were required to perform six trials with assistive methods and one trial without assistance. The results demonstrated that the supporting system decreased the lane departure risk in the lane keeping tasks and could support a fast and stable lane changing maneuver.

A miniaturized attitude control system (ACS), which is capable of attaining a high spin rate and good pointing accuracy, is an integral part of any small spacecraft. In this regard, embedded magnetorquers are gaining significant attention because they are inserted in printed circuit board (PCB) internal layers with no extra space occupation and result in almost no mass and development cost. In this article, an innovative embedded magnetorquer with asymmetric nonuniform geometric structure is presented. The proposed magnetorquer is optimized for various parameters of interest, i.e., magnetic moment, resultant generated torque, power consumed, and heat dissipation for a CubeSat standard nanosatellite by means of employing diverse nonunity track-width-ratio geometrical arrangements. The magnetorquer driver and reconfigurable circuit is implemented with commercial-off-the-shelf (COTS) components which are low cost and easily available from the market. Embedded coils with variable trace width were simulated in order to predict the accuracy and to achieve the maximum torque versus power dissipation ratio of the developed models. Time-varying rotational analyses are performed to evaluate the angular spin rates driven by the asymmetric coils. Due to embedded coil structure, a detailed thermal analysis is conducted for various coil configurations (i.e., series, parallel, hybrid, etc.) to preserve thermal limits and to ensure the efficacy of the system. The simulation results were validated through a comprehensive set of experimental measurements which also establishes the framework for selecting the optimal coils configuration based on specific mission requirements.