Search

Background: Recent advancements in artificial intelligence have proven their effectiveness in orthopaedic settings, especially in tasks like medical image analysis. This study compares human musculoskeletal radiologists to artificial intelligence in a novel, detailed, short, and cost-effective examination of Achilles tendon magnetic resonance images to uncover potential disparities in their reasoning approaches. Aiming to identify relationships between the structured assessment of the Achilles tendon and its function that could support injury prevention. We examined 72 athletes to investigate the link between Achilles tendon structure, as visualised in magnetic resonance images using a precise T2*-weighted gradient echo sequence with very short echo times, and its functional attributes. The acquired data were analysed using advanced artificial intelligence techniques and reviewed by radiologists. Additionally, we conducted statistical assessments to explore relationships with functional studies in four meaningful groups: dynamic strength, range of motion, muscle torque and stabilography. Results: The results show notable linear or non-linear relationships between functional indicators and structural alterations (maximal obtained Spearman correlation coefficients ranged from 0.3 to 0.36 for radiological assessment and from 0.33 to 0.49 for artificial intelligence assessment, while maximal normalised mutual information ranged from 0.52 to 0.57 for radiological assessment and from 0.42 to 0.6 for artificial intelligence assessment). Moreover, when artificial intelligence-based magnetic resonance assessment was utilised as an input, the associations consistently proved more robust, or the count of significant relationships surpassed that derived from radiological assessment. Ultimately, utilising only structural parameters as inputs enabled us to explain up to 59% of the variance within specific functional groups. Conclusions: This analysis revealed that structural parameters influence four key functional aspects related to the Achilles tendon. Furthermore, we found that relying solely on subjective radiologist opinions limited our ability to reason effectively, in contrast to the structured artificial intelligence assessment. Study Design: Cross-sectional studies. Key Points: •Establishment of a relationship between magnetic resonance imaging-based structural features and functional characteristics of the Achilles tendon, emphasising non-linear connections. •Introduction of a fast and efficient magnetic resonance imaging protocol for concurrent evaluation of structural and functional aspects, alongside a comparative analysis of artificial intelligence and radiologist reasoning capabilities. •Highlighting the advantages of artificial intelligence-driven reasoning in identifying structural biomarkers, offering potential enhancements for injury prevention strategies and personalised treatment approaches. [ABSTRACT FROM AUTHOR]

Screw anchor foundations are widely used due to their fast construction speed and low construction difficulty. Despite their prevalent use, limited research on the ultimate uplift bearing capacity of screw anchor foundations in silty clay has been presented in recent years. In this paper, we conducted experiments on two types of screw anchor foundations, systematically comparing the impacts of various factors such as embedment depth, anchor rod diameter, anchor plate quantity, and tilt angle on the resulting ultimate uplift bearing capacity. The test results of meticulously recorded torque, failure modes, and crack distributions of screw anchors facilitated the derivation of theoretical calculation formulas for both shallow and deep ultimate uplift bearing capacities. Research has indicated that with increasing embedment depth and anchor plate quantity, the ultimate bearing capacity, torque, and torque coefficient of screw anchors increase. However, due to the disturbance and uneven distribution of the upper soil, this increase is nonlinear. Increasing the tilt angle reduces the ultimate bearing capacity, torque, and torque coefficient of screw anchors with a φ89 mm anchor rod, while it increases the torque coefficient of the φ140 mm anchor rod. By comparing the derived theoretical formulas with the experimental results, the validity of the theoretical formulas is confirmed. [ABSTRACT FROM AUTHOR]

The torque ripples resulting from external electromagnetic excitation and mechanical internal excitation contribute to significant torsional vibration issues within electromechanical coupling systems. To mitigate these fluctuations, a passive control strategy centered around a multi-stable nonlinear energy sink (MNES) is proposed. First, models for electromagnetic torque, gear nonlinear meshing torque, and misalignment torque are established. Building upon this foundation, an electromechanical coupling dynamic model of the electric drive system is formulated. Sensitivity analysis is conducted to determine the sensitive nodes of each mode and to provide guidance for the installation of the MNES. The structure of the MNES is introduced, and an electromechanical coupling dynamic model with the MNES is established. Based on this model, the influence of the misaligned angle on the electromechanical coupling characteristics is analyzed. In addition, the vibration suppression performance of the MNES is studied under both speed and uniform speed conditions. Finally, experimental testing is conducted to verify the vibration suppression performance of the MNES. The results indicate that misalignment triggers the emergence of its characteristic frequencies and associated sidebands. Meanwhile, the MNES effectively mitigates the torsional vibrations in the coupled system, demonstrating suppression rates of 52.69% in simulations and 63.3% in experiments. [ABSTRACT FROM AUTHOR]

Accurate magnetic field calculation is the premise of electromagnetic performance prediction. Conventional subdomain (SD) techniques assume that the iron's relative permeability is infinite, leading to falsely overestimated flux density. We propose an accurate magnetic field analytical model for permanent magnet (PM) in-wheel machines considering iron's magnetization nonlinearity and saturation. Specifically, according to the excitation source and topology, the entire solution domain of the machine is divided into sub-regions such as stator slots/teeth, stator slot-openings/tooth-tips, air-gap, and rotor slots/teeth, etc. Poisson's or Laplace's magnetic vector potential (MVP) equations are solved using Maxwell's electromagnetic theory and complex Fourier series methods in each sub-region. Specifically, in our approach, The Cauchy product theorem addresses the discontinuous magnetic permeability change at the slot and tooth interface. The machine's magnetic saturation effect is considered by combining the actual magnetization characteristics of iron with an iterative algorithm. The general solution for the MVP is solved using the boundary conditions between adjacent subregions. Subsequently, electromagnetic properties such as air-gap flux density, back electromotive force (EMF), and electromagnetic torque are obtained. The accuracy of the analytical model is verified by finite element analysis (FEA) and prototype tests, which proved that the proposed analytical model can consider the iron's nonlinearity and the magnetic saturation. In addition, the inaccurate overestimation of electromagnetic torque and air-gap magnetic flux density by the conventional SD techniques has also been proven. [ABSTRACT FROM AUTHOR]

Purpose: Muscle, tendon, and muscle–tendon unit (MTU) stiffness as well as passive peak torque (PPT) or delayed stretching pain sensation are typical explanatory approaches for stretching adaptations. However, in literature, differences in the study inclusion, as well as applying meta-analytical models without accounting for intrastudy dependency of multiple and heteroscedasticity of data bias the current evidence. Furthermore, most of the recent analyses neglected to investigate PPT adaptations and further moderators. Methods: The presented review used the recommended meta-analytical calculation method to investigate the effects of stretching on stiffness as well as on passive torque parameters using subgroup analyses for stretching types, stretching duration, and supervision. Results: Chronic stretching reduced muscle stiffness (− 0.38, p = 0.01) overall, and also for the supervised (− 0.49, p = 0.004) and long static stretching interventions (− 0.61, p < 0.001), while the unsupervised and short duration subgroups did not reach the level of significance (p = 0.21, 0.29). No effects were observed for tendon stiffness or for subgroups (e.g., long-stretching durations). Chronic PPT (0.55, p = 0.005) in end ROM increased. Only long-stretching durations sufficiently decreased muscle stiffness acutely. No effects could be observed for acute PPT. Conclusion: While partially in accordance with previous literature, the results underline the relevance of long-stretching durations when inducing changes in passive properties. Only four acute PPT in end ROM studies were eligible, while a large number were excluded as they provided mathematical models and/or lacked control conditions, calling for further randomized controlled trials on acute PPT effects. [ABSTRACT FROM AUTHOR]

Acute sleep restriction (SR) reduces strength through an unknown mechanism. Purpose: To determine how SR affects quadriceps contractile function and recruitment. Methods: Eighteen healthy subjects (9 M, 9F, age 23.8 ± 2.8y) underwent isometric (maximal and submaximal), isokinetic (300–60°·s−1), and interpolated twitch (ITT) assessment of knee extensors following 3d of adequate sleep (SA; 7–9 h·night−1), 3d of SR (5 h·night−1), and 7d of washout (WO; 7-9 h·night−1). Results: Compared to SA (227.9 ± 76.6Nm) and WO (228.19 ± 62.9Nm), MVIC was lesser following SR (209.9 ± 73.9Nm; p = 0.006) and this effect was greater for males (− 9.8 v. − 4.8%). There was no significant effect of sleep or sleep x speed interaction on peak isokinetic torque. Peak twitch torque was greater in the potentiated state, but no significant effect of sleep was noted. Males displayed greater potentiation of peak twitch torque (12 v. 7.5%) and rate of torque development (16.7 v. 8.2%) than females but this was not affected by sleep condition. ITT-assessed voluntary activation did not vary among sleep conditions (SA: 81.8 ± 13.1% v. SR: 84.4 ± 12.6% v. WO 84.9 ± 12.6%; p = 0.093). SR induced a leftward shift in Torque-EMG relationship at high torque output in both sexes. Compared to SA, females displayed greater y-intercept and lesser slope with SR and WO and males displayed lesser y-intercept and greater slope with SR and WO. Conclusions: Three nights of SR decreases voluntary isometric knee extensor strength, but not twitch contractile properties. Sex-specific differences in neuromuscular efficiency may explain the greater MVIC reduction in males following SR. [ABSTRACT FROM AUTHOR]

Experimental observations have revealed a change in the concavity of the resultant force-displacement plot in the extension test for pantographic sheets. In this paper, we aim to relate these macroscopically observed mechanical properties with the microscale properties of the hinges (or pivots) connecting the pantographic fibers. The material constituting the hinges is modeled at the microscale as an isotropic elastoplastic 3D Cauchy continuum. The elastic regime is assumed to be linear, while the plastic regime exhibits either saturating or non-saturating hardening. In the case of circular homogeneous cylindrical hinges, monotonic loading is considered to derive a mesoscale constitutive relation linking the torsional angle to the total applied torque. It is demonstrated that (non-)saturating hardening at the microscale results in (non-)saturating hardening of the twist angle/torque plot at the mesoscale, which itself is responsible for the change of concavity in bias extensional test of pantographic sheets. [ABSTRACT FROM AUTHOR]

In this study, analytical solutions are presented for the flexural–torsional coupled vibration response analyses of thin-walled beams under bidirectional moving random loads. Based on classical Euler–Bernoulli and Vlasov beam theories, the governing dynamic equations considering the influence of additional torque have been established. The modal superposition method, the Laplace transform, and the Duhamel's integral technique have been employed to obtain the average value and standard deviation of beam displacements in vertical, lateral, and torsional directions. For the validation of the proposed formulations, the results obtained in this paper are compared with the results acquired by the Newmark-β method and the Monte Carlo method. Comparisons of the results prove the accuracy of the suggested formulations. Through the parametric analysis, it is confirmed that the position where the average value reaches its maximum is related to the load velocity. But the maximum standard deviation always occurs at the end of the beam, which decreases with the growth of velocity and the drop in span. When the velocity does not exceed 30 m/s, the displacement response is mainly controlled by low-order modes. [ABSTRACT FROM AUTHOR]

In this study, a new comprehensive fully coupled elastic-hydrodynamic model is developed for a multi-layer gas foil thrust bearing (GFTB). The interaction effects among the top foil, back board, middle foil, and bottom foil, as well as the Coulomb friction effect, are considered. The stiffness and static characteristics obtained by the experimental and theoretical approaches are in good agreement, which verifies the accuracy of the model. The contribution of each foil layer to the overall stiffness and the load-carrying mechanism are analyzed. Interaction effects of the load, preload, and rotational speed on the static performance are investigated comprehensively. Furthermore, start-stop tests are performed to achieve the lift-off speed, start-up torque, and shut-down torque under various operating conditions. [ABSTRACT FROM AUTHOR]

In this research, the effect of tool pin geometry on the development of heat, torque and force during friction stir welding of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) plate by using double shoulder tool was examined. The overarching aim is to investigate a suitable tool pin geometry that can provide a considerable amount of weld properties. The experiments were conducted with L9 orthogonal array full factorial design based on the Taguchi method by considering a combination of two factors and three levels. Three different pin profiles, including plane tapered, threaded cylindrical and threaded tapered tool pin profile were considered with varying tool rotational speed (800, 1200, and 1600 rpm). The variation in microstructure and mechanical properties with the change of torque, forces and heat input generated during weld is observed and analyzed. A maximum ultimate tensile strength (UTS) of 21.61 MPa and joint efficiency of 70.55% was obtained at 1600 rpm by using tapered threaded tool pin profile. Microstructural analysis of maximum UTS revealed thin and uniform interface layer with mechanical transportation phenomenon. Highlights: The acrylonitrile butadiene styrene and polycarbonate are feasible to produce sound weld joint. The sound welds with defect free joint produced by arranging harder material at advancing side with 1 mm offset towards softer material side. Microstructure study of the sample with maximum UTS showed a very thin, continuous and uniform interface layer with macro-interlocked structure, which resulted in excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Monitoring forming forces in metal forming processes is essential for analyzing process behaviors, mechanisms, and defect detection. This is particularly relevant in aluminum tube bending processes, where the dimensional quality of the formed product is sensitive to multiple upstream and in-process variables. This research presents a method for real-time, in-process monitoring of forming forces in rotary draw bending (RDB). By developing a set of innovative forming tools (clamp die, bend die, pressure die, etc.) with directional force sensors embedded, key forming forces are measured. Through a series of experiments, the measurement method was validated by analyzing both measured forces and calculated moments, demonstrating high measurement consistency. The systematic examination of measurement variations provided insights into the reliability and robustness of the method. Moreover, comparison with FE results supported the accuracy of the measurements. Additionally, laser-based measurements showed a good correlation between the measured springback angle and the calculated moment during bending. These findings lay the groundwork for the industrial implementation of in-process force measurements in RDB, advancing the production of tube components. [ABSTRACT FROM AUTHOR]

With the continuous development of underground engineering construction in China, it is particularly important to study the identification of structural plane characteristics of rock masses. In this study, three types of pseudo-rock specimens with structural plane interlayers were fabricated to analyze the patterns of drilling parameter changes in rock bodies with structural planes during the drilling process and to explore the characterization and identification methods of rock body structural planes. Gneiss, granite, and sandstone were used as rock materials, with gypsum mortar as the interlayer material for the structural planes in these three types of specimens. The indoor digital drilling equipment was utilized for conducting indoor digital drilling experiments. The variation patterns of drilling parameters in rock bodies with structural surfaces under different interlayer inclinations and thicknesses were analyzed. The relationship between the ratio of the change in rotational speed and drilling speed during the stable phase of the upper rock mass and the peak torque and peak drilling pressure has been established. The relationship between the structural plane inclination angle and the ratio of change in rotational speed and drilling speed has been determined. By utilizing the variation in these ratios, the impacts of the structural plane inclination angle and the thickness of the structural plane on the peak torque and peak drilling pressure have been elucidated. The research results provide a theoretical basis for the stability evaluation of rock masses with structural planes under drilling action. [ABSTRACT FROM AUTHOR]

The orbital Hall effect in light materials has attracted considerable attention for developing orbitronic devices. Here we investigate the orbital torque efficiency and demonstrate the switching of the perpendicularly magnetized materials through the orbital Hall material, i.e., Zr. The orbital torque efficiency of approximately 0.78 is achieved in the Zr orbital Hall material with the perpendicularly magnetized [Co/Pt]3 sample, which significantly surpasses that of the perpendicularly magnetized CoFeB/Gd/CoFeB sample (approximately 0.04). Such a notable difference is attributed to the different spin-orbit correlation strength between the [Co/Pt]3 sample and the CoFeB/Gd/CoFeB sample, confirmed through theoretical calculations. Furthermore, the full magnetization switching of the [Co/Pt]3 samples with a switching current density of approximately 2.6×106 A/cm2 has been realized through Zr, which even outperforms that of the W spin Hall material. Our finding provides a guideline to understand orbital torque efficiency and paves the way for developing energy-efficient orbitronic devices. Orbitronics opens an avenue for developing energy-efficient memory and logic devices through orbital Hall effect. Here, the authors realize the magnetization switching of perpendicularly magnetized materials through the orbital torque. [ABSTRACT FROM AUTHOR]

Fractional slot concentric winding (FSCW) machine features with short end winding, high torque density and good fault tolerance. However, this type of machine suffers from abundant MMF harmonics which causes high iron loss and partial saturation, etc. Hence, majority of the FSCW adopts surface-mounted PM (SPM) rotor which have large effective airgap to minimize the influence of the MMF harmonics while the interior PM (IPM) rotor is rarely used. The SPM rotor tends to induce high PM flux linkage and cause large fault current when experiencing a short-circuit failure. As a result, this paper presents a triple 3-phase FSCW-IPM for fault-tolerant applications. The triple 3-phase windings facilitate the uninterrupted fault tolerant operation, the more even distributed windings also induce a more sinusoidal MMF which enables the application of IPM rotor. The IPM rotor reduces the PM usage while reluctance torque can be explored to compensate the PM torque reduction which improves the machine fault tolerance. As a result, the proposed machine owns good performance and excellent fault tolerance. The machine is investigated by electromagnetic and thermal finite element analysis and prototyping tests. Both findings confirm that the proposed triple 3-phase FSCW-IPM is a competitive solution for high reliability application. [ABSTRACT FROM AUTHOR]

This paper proposes a method for the torque ripple reduction of an open-end winding interior permanent magnet synchronous motor (OEW-IPMSM) using direct self-control (DSC). The conventional DSC has been researched in high-power systems because of its advantages in terms of a low switching frequency and a fast response of torque. Nevertheless, high torque ripple is a disadvantage of the conventional DSC. This is because the trajectory of the stator flux is controlled in the shape of a hexagon for lower switching frequencies and by applying hysteresis torque control. In this paper, predictive torque control using a mathematical model of an OEW-IPMSM is presented to improve the quality of the torque control. In addition, the presented method addresses the trajectory control of the flux using the diverse voltage vectors of the dual inverter. The validity of the presented method is demonstrated by simulations and experimental results. [ABSTRACT FROM AUTHOR]

Aiming at the problem of torque fluctuations and intake pressure fluctuations caused by cycle cylinder deactivation, we introduced a refined control strategy encompassing fixed cycle frequency with fixed deactivation frequency, variable cycle frequency with fixed deactivation frequency, and variable cycle frequency with variable deactivation frequency. The cycle cylinder deactivation rate is determined by controlling the cycle frequency and the cylinder deactivation frequency, which provides a new method for exploring the torque fluctuation of the cycle cylinder deactivation. Furthermore, we introduced an intake compensation method based on the cylinder deactivation compensation coordinate system is proposed. The non-uniformity of the intake air volume of each cylinder of the cycle cylinder deactivation is improved by changing the valve lift. After compensation, the non-uniformity of the intake air volume and the mean indicated pressure of each cylinder are within 2%, and the maximum torque fluctuation is reduced by 52%. It provides a useful reference for enhancing the dynamic smoothness of cylinder deactivation in engines. [ABSTRACT FROM AUTHOR]

Ultrafast manipulation of the Néel vector in metallic antiferromagnets most commonly occurs by generation of spin-orbit (SOT) or spin-transfer (STT) torques. Here, we predict another possibility for antiferromagnetic domain switching by using novel laser optical torques (LOTs). We present results of atomistic spin dynamics simulations from the application of LOTs for all-optical switching of the Néel vector in the antiferromagnet Mn2Au. The driving mechanism takes advantage of the sizeable exchange enhancement, characteristic of antiferromagnetic dynamics, allowing for picosecond 90 and 180-degree precessional toggle switching of the Néel vector with laser fluences on the order of mJ/cm2. A special symmetry of these novel torques greatly minimises the over-shooting effect common to precessional spin switching by SOT and STT methods. We demonstrate the opportunity for LOTs to produce deterministic, non-toggle switching of single antiferromagnetic domains. Lastly, we show that even with sizeable ultrafast heating by laser in metallic systems, there exist a large interval of laser parameters where the LOT-assisted toggle and preferential switchings in magnetic grains have probabilities close to one. The proposed protocol could be used on its own for all-optical control of antiferromagnets for computing or memory storage, or in combination with other switching methods to lower energy barriers and/or to prevent over-shooting of the Néel vector. [ABSTRACT FROM AUTHOR]

An elastic rod is perfectly bonded to a von Kármán elastic plate such that, except for a relative twist, no relative displacements are allowed between the rod and the plate. The deformation of the confined rod is strongly coupled to that of the flexible environment to which it has to necessarily confirm. A framework is developed where, for a given distribution of growth strains in the rod, the shape as well as the internal forces and the internal moments of the rod-plate system can be determined. The nature of mechanical interaction between the rod and the plate is discussed in detail. The boundary-value-problems, to be solved for a scalar stress function and a scalar transverse displacement field, both piecewise-smooth in the plate domain, include in-plane strain compatibility conditions and transverse force equilibrium equations on, and away from, the curve of rod-plate intersection. [ABSTRACT FROM AUTHOR]

This paper presents a simple and effective sensorless control strategy based on extended state observers (ESOs) to enhance the performance of brushless DC (BLDC) motors. First, an ESO is used to estimate the back-electromotive force (EMF) without additional filters. Second, another ESO is incorporated into the quadrature phase-locked loop (QPLL) to enable the implementation of an active harmonic compensator to reduce noise harmonics induced by the estimated back-EMF. By using the P-Q theory, the proposed compensator calculates a compensation signal to be directly injected into the QPLL based on ESO. The results analysis shows that the proposed strategy significantly reduces torque ripples and speed/position estimation errors under a wide range of speeds. [ABSTRACT FROM AUTHOR]

In this work, research was carried out to assess the possibility of producing rods from magnesium ingots and to study their structure and properties under various geometric and technological parameters of the combined rolling-extrusion (CRE) process. The values of the energy-power parameters of the process were determined. Data were obtained on the forces acting on the rolls and on the die, as well as torques on the rolls with a closed box gauge. The patterns of their changes have been established depending on the heating temperature of the workpiece, drawing ratio during extrusion and various sizes of calibers used on the existing combined processing units CRE-200 and CRE-400. Tools and equipment were selected to carry out experimental research by determining the required power of the drive electric motors of these units. A model has been designed to simulate the CRE process for producing Mg rods of a given chemical composition. Calculation of energy-force parameters using the model using the calculated processing mode showed that the obtained values of forces and moments during the implementation of the CRE process correlate with the results obtained during its analytical assessment. Corresponding experimental studies showed the adequacy of the model and analytical calculations. Pilot batches of rods with a diameter of 5 and 9 mm from cast magnesium ingots are produced. The physical and mechanical properties and structure of the resulting semi-finished products were investigated. Recommendations were given on the choice of metal processing temperature to reduce the size of recrystallized grains obtained at relatively large strain. Based on the research results, it was concluded that it is possible to obtain high-quality deformed semi-finished products from cast magnesium billets with a high level of strength properties and sufficient plastic properties. [ABSTRACT FROM AUTHOR]

The tightness and stability of the pipe connections are particularly important for pressurized environments. Pipe fittings are one of the most important subgroups of fittings. These fittings are not only used for connection purposes, but these fasteners may also have additional purposes such as sealing. In this study, a simulation model of the pipe fitting was created to evaluate the sealing performance. The obtained forces in the simulations were then used in the modified version of the classical bolt-tightening moment equation. In this equation, the additional parameter, R, is embedded. This parameter depends on the distance from the center (torque arm, x), slope parameter (k), and friction constant (S) between the body or nut and the ring parts. The consistency and applicability of the new equation were discussed by comparing the obtained results with the experimental results. It has been observed that there is a good agreement between the comparative results. [ABSTRACT FROM AUTHOR]

This paper presents an improved analytical formulation for analyzing the sliding friction torque in cylindrical roller bearings (CRBs), which are renowned for their outstanding radial load-carrying capacity. Although sliding friction in CRBs typically employs a minor heat source during rotation, its association with the roller-bearing starting torque is vital. In particular, their impact is substantial at higher rotational speeds when the centrifugal forces come into play. The intricacy lies in the manifestation of sliding friction torque between the rollers and races, stemming from non-uniform surface deformation. Two key aspects of the CRB sliding friction torque are considered in this study, the differential sliding friction torques caused by roller rotation and roller orbital motion. Additionally, a computational method for evaluating sliding friction based on pure rolling lines (PRLs) in the race contact area is introduced. This method incorporates an innovative updating algorithm that provides more precise insights into PRLs and sliding friction torque. The effectiveness of the proposed approach was then established through a comparative analysis of the empirical formulas provided by bearing manufacturers. This comparison underscores the potential of the method as a useful tool for comprehending and quantifying sliding friction torque within CRBs. [ABSTRACT FROM AUTHOR]

The twin-screw extrusion (TSE) process has recently been investigated for the production of cellulose nanofibrils (CNF). The main advantage of this process is the production of CNF at high solid content (around 20 wt% suspensions) and lower energy consumption. Typically, studies focus on the quality of the extruded material (i.e., CNF) by comparing different pretreatments, biomass sources or combinations of processes. Limited information is available on the TSE process itself and its stability. This work proposes to analyze some key parameters such as torque, in situ temperature and flow of extruded material. All together they reflect a certain stability of the TSE process. The process is considered stable when the torque and temperatures plateau and when the mass flow is continuous and constant. These parameters vary depending on the different pretreatments and the solid content of the cellulose suspensions introduced in the TSE. Morphologies of extruded CNF are characterized at different scales with optical microscopy, SEM-FEG and TEM images. A simplified quality index was calculated to compare extruded CNF. A high and fluctuating torque, rising temperatures and discontinuous mass flow were recorded for the enzymatically pretreated pulp and refined pulp with a long dwell time of the fibers in the extruder. On the contrary, a low and very stable torque, stabilized temperatures and continuous mass flow were reported for the pulp obtained after a combination of enzymatic hydrolysis and refining. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to statistically compare the rate of torque development normalized by maximal strength (relative RTD) across ankle angles. Additionally, this study was aimed at exploring the correlation coefficients between relative RTD and passive stiffness of the medial gastrocnemius (MG) at different ankle angles. Methods: Twenty-two healthy men and women (age: 31 ± 4 years) performed randomly-ordered explosive isometric plantar flexions at plantarflexed (15°), neutral (0°), and dorsiflexed (− 15°) angles; relative RTD comprised the slope of the time–torque curve normalized to maximal torque. The shear wave velocity (SWV; index of stiffness) of the MG at rest was measured at each angle using ultrasound shear wave elastography. Results: The relative RTD was greater at 15° than − 15° for 0–50, 0–100, and 0–150 ms time-windows and at 15° than 0° for the 0–150 ms time-window (P < 0.05), although peak torque was lower at 15° than 0° and − 15° (P < 0.05). The relative RTD for the 0–50 ms time-window correlated with SWV at − 15° (rs = 0.475, P < 0.05), but not at 15º and 0º. Furthermore, the correlation coefficient of RTD for the 0–100 ms time-window with SWV was significantly greater at − 15° (rs = 0.420) than 0 ° (rs = − 0.109). Conclusions: A greater relative RTD occurs at plantarflexed angles (i.e., the ascending limb of the force–length curve) in the triceps surae, and relative RTD is strongly related to passive MG stiffness at dorsiflexed angles (i.e., longer muscle lengths). [ABSTRACT FROM AUTHOR]

Background: Maximal conditioning contractions (CCs) can lead to the enhancement of evoked-twitch characteristics in human skeletal muscle. This phenomenon is termed post-activation potentiation (PAP). In the knee extensors, PAP is greater in men compared with boys. In adults, the optimal CC duration for PAP is ~ 10 s. We examined child–adult differences in PAP among females and aimed to determine the optimal CC duration in girls and women. Methods: Eleven girls (9.3 ± 1.4 years) and 13 women (23.4 ± 2.7 years) participated in this study. Maximal isometric evoked twitches were recorded in the knee extensors before and after 4 maximal CCs of different durations (5, 10, 20, and 30 s), in a random order. PAP was calculated as the percent-change in peak torque (Tpeak) and peak rate of torque development (RTDpeak) after each CC. Results: There was a group-by-duration interaction (p < 0.001), reflecting greater Tpeak PAP in women compared with girls following 5 and 10 s CCs, and lower RTDpeak PAP in women following the 30 s CC. The 5 and 10 s CCs lead to the greatest Tpeak and RTDpeak PAP amongst the women while there were no differences between CC durations in girls. Conclusion: After both a 5 and 10 s CC, women have greater PAP compared with girls. The optimal CC duration for the knee extensors in women appears to be ~ 5-10 s, while CC durations between 5 and 30 s do not appear to affect levels of PAP in girls. [ABSTRACT FROM AUTHOR]

Purpose: Static stretching (SS) improves flexibility but may impair the accuracy of joint position sense. Therefore, this study aimed to investigate the acute effects and time course of SS on the accuracy of joint position sense, range of motion (ROM), and muscle–tendon unit (MTU) stiffness. Methods: This study randomly assigned 16 healthy, young males to the SS and control conditions. SS intervention in the SS condition was performed on the plantar flexors of the dominant leg for three sets of 60 s. The participants were instructed to sit for 240 s in the control condition. The ankle dorsiflexion (DF) ROM, passive torque at DF ROM, MTU stiffness, and joint position sense on the dominant leg side were measured before (PRE) and immediately (POST) and at 5, 10, and 20 min postintervention. Results: A significant interaction effect was observed in the relative error in the joint position sense, and significant increases were noted in POST compared to PRE in the SS condition. Further, significant interactions were observed in DF ROM, passive torque at DF ROM, and MTU stiffness. The SS condition demonstrated significant increases in DF ROM and passive torque at DF ROM compared to PRE with POST, 5 min, and 10 min, and MTU stiffness significantly decreased in POST compared with PRE. Conclusion: Our results indicated that the accuracy of the joint position sense decreased immediately after SS, but returned to baseline in a very short time. [ABSTRACT FROM AUTHOR]

Severe torque ripple and determination of the weighting factor pose significant challenges in traditional predictive torque control. A deadbeat predictive torque control scheme designed to minimize torque ripple for dual three-phase permanent magnet synchronous motors is proposed in this paper, eliminating the need for a cost function. Additionally, a novel method for calculating action time based on geometric principles is proposed. First, the deadbeat direct torque and flux control is employed to obtain the reference voltage vector. To reduce the computational burden, the nearest virtual voltage vector is selected directly without a cost function. Subsequently, the torque ripple is further reduced by calculating the corresponding action time based on the introduced geometric relationship in the volt-sec coordinate system. Finally, experimental results demonstrate the effectiveness of the torque ripple reduction method under different working conditions. [ABSTRACT FROM AUTHOR]

In view of the disadvantages of negative torque and low operation efficiency in the traditional direct torque control (DTC) for the switched reluctance motor drive (SRD), a novel DTC strategy based on optimal turn-on angle is proposed in this paper. First, the flux hysteresis controller of the traditional DTC is cancelled and the SRM is only controlled by the torque hysteresis controller. The actual rotor position angle is used to divide the sectors instead of the angle calculated by the stator flux, which does not need to select the optimal given flux value, and makes the division of sectors more in line with the inductance characteristics of the SRM. Second, the function for calculating the optimal turn-on angle is designed and the sectors are reallocated. The optimal voltage vector is selected according to the output signal of the torque hysteresis controller and sector position. Finally, the 12-sector DTC method is selected as comparison algorithm and the correctness of the proposed method is confirmed by simulation and experimental results. It is demonstrated that the proposed strategy retains the advantages of the simple structure of the traditional DTC. In addition, it eliminates negative torque, improves the DC bus voltage utilization and torque ampere ratio, and reduces the torque ripple, switching frequency and copper losses. [ABSTRACT FROM AUTHOR]

In the constrained Cosserat theory of a rod with a rigid cross-section, the balance of angular momentum is satisfied by a restriction on the constitutive equations that requires a second order tensor to be symmetric. The kinematics of the rod are determined by satisfying the balances of linear and director momentum and kinematic constraints. In contrast, the Antman model for a special Cosserat theory of rods proposes constitutive equations directly for the force and mechanical moment applied to the rod and the kinematics are determined by the balances of linear and angular momentum. These two models differ by their treatment of angular momentum. This note poses and answers the question: Are the solutions of these two models identical for the same strain energy? [ABSTRACT FROM AUTHOR]

Accurate prediction of cutting force is essential not only for estimating power and torque but also for precise chatter prediction, where even the derivative of the cutting force function is crucial. The traditional cutting force model does not consider the runout, and the enhanced models that consider it are often difficult to be established due to the need of physical runout measurements. This study proposes a newly developed split-wise model to predict the cutting forces in Al2024. This model includes the calculation of the cutting force considering individual teeth which leads to the determination of 6 force coefficients of different values per tooth. The experiments were conducted on milling Al2024 for two set of experiments ( V fz = 375–675 m/min, a e = 4–12 mm, a p = 0.5–1 mm, D =16 mm) and ( V fz = 220–440 m/min, a e = 0.5–1 mm, a p = 0.5–1 mm, D =2 mm). For the first set, the comparative error determined from the split-wise and classic models is 5.6% and 7.8%, respectively. For the second set, the error is 11% and 15.7%, respectively. Therefore, the split-wise cutting force model is capable of adapting the runout and consequently improving the prediction of the cutting force with both large and small tools operations. Additionally, the split-wise may find applications in advanced manufacturing technologies allowing industries to enhanced productivity and quality. [ABSTRACT FROM AUTHOR]

This research paper introduces the Double Stator (DS) Hybrid Excitation (HE) Halbach Permanent Magnet (HPM) Flux Switching (FS) machine. The machine construction and its optimization specifically designed for electric vehicle (EV)/hybrid electric vehicle (HEV) traction applications are investigated. The optimization using a multi-objective Genetic Algorithm is conducted following a sensitivity analysis-based identification of key optimization parameters and constraints. The finite element results are compared with the performance of a state-of-the-art benchmark FSPM machine having identical PM volume and winding current densities. The proposed design is shown to outperform the benchmark with 16.2% increase in back-electromotive force and 14.7% reduction in cogging torque. Furthermore, the average torque is improved at flux-enhancing operation by 20.8%, and the torque ripple is reduced by 9.9%. Notably, the proposed machine also is capable of flux regulation thereby having the ability to operate in a wide speed range. A detailed explanation of the reasons for the significant improvements in the proposed machine structure is provided to offer a comprehensive understanding of its rationale. These research findings indicate that this innovative DS-HE-HPM-FS machine can enhance the performance of EVs and HEVs. [ABSTRACT FROM AUTHOR]

A method and results of model studies of the operation of a proposed new system for mechanized feeding of filler sand to the ladle nozzle are presented. The design solutions incorporated into the system and the relationships obtained to justify its energy-force parameters are validated. [ABSTRACT FROM AUTHOR]

For the multi joint humanoid multi fingered dexterous hand, people always hope that it can grasp objects accurately, stably and compliantly, which is a challenging task. In this paper, by constructing the dynamics model of the multi joint humanoid multi fingered dexterous hand and using the distributed parameter boundary control strategy, the improved force/position hybrid control (IF/PHC) system is designed, and the stability and convergence of the poposed control strategy are analyzed. Through simulation and experiments, the advantages of the proposed control method in this study over the traditional methods are demonstrated, the proposed method can greatly reduce the position error, and the required driving torque and energy consumption are also reduced to a certain extent, and the common soft and fragile objects are grasped to verify the effectiveness of the method proposed. [ABSTRACT FROM AUTHOR]

Full stress/displacement compatibility conditions at interfaces by considering the bilinear elasto-plastic core are investigated for the first time. The paper uses the concepts of the improved high-order sandwich panel theory (IHSAPT) and generalizes the approach to account for the bending response based on the unique mechanism of geometrical and material nonlinearity. The analytical results of the model are presented and compared with the experimental results. Emphasis is placed on satisfying shear stress compatibility conditions at the interface along with the effects of the plastic modulus of the core to provide a unique perspective on the bending response of sandwich panels. The results of the present approach are in good agreement with experimental results in terms of load–displacement, including the localized effects attributed to the flexible core. It is also shown that the present model can identify and quantify the localized effects of shear stress continuity at interfaces while conventional high-order sandwich panel models available in the literature fail to do so. The results of the study contribute to the effects of shear and normal plastic modules of the core on transverse normal and shear stress distributions at top and bottom interfaces, stress and displacement components through the thickness of the core as well as the force and moment resultants, and transverse displacements in the face sheets, which may be used as benchmark results for future studies. [ABSTRACT FROM AUTHOR]

Purpose: The capacity to explosively contract quadriceps within the critical timeframe associated with anterior cruciate ligament (ACL) injury, quantified by the rate of torque development, is potentially essential for safe landing mechanics. This study aimed to investigate the influence of explosive quadriceps strength on ACL‐related sagittal‐plane landing mechanics in females with and without ACL reconstruction (ACLR). Methods: Quadriceps explosive strength and landing mechanics were assessed in 19 ACLR and 19 control females during isometric contractions and double‐ and single‐leg jump landings. A stepwise multiple linear regression model determined the variance in each of the landing biomechanics variables for the ACLR limb and nondominant limb of controls that could be explained by the group, rate of torque development and/or their interaction. If peak kinetic variables could be predicted by the rate of torque development or interaction, additional analyses were conducted, accounting for knee flexion as a covariate in the regression model. Results: During single‐leg landings, ACLR females exhibited greater knee flexion at initial contact than controls (p = 0.04). Greater quadriceps rate of torque development predicted higher peak posterior ground reaction force and anterior tibial shear force in both groups (p = 0.04). However, after controlling for knee flexion angle at those peak forces, quadriceps rate of torque development was not predictive. In double‐leg landings, greater explosive quadriceps strength was associated with quicker attainment of peak knee extension moment and posterior ground reaction force in the ACLR limb (p = 0.03). Conclusion: Regardless of ACL injury status, females with greater explosive quadriceps strength adopted safer single‐leg landings through increased knee flexion, potentially mitigating ACL loading despite encountering higher peak forces. During double‐leg landings, a greater explosive quadriceps strength of the ACLR limb is associated with faster achievement of peak force upon landing. Incorporating explosive quadriceps strengthening into post‐ACLR rehabilitation and injury prevention programmes may enhance landing mechanics for reducing primary and subsequent ACL injury risks. Level of Evidence: Level II. [ABSTRACT FROM AUTHOR]

Objectives: Evaluate the 5-year safety and efficacy of a narrow-diameter (3.0 mm) implant that was immediately provisionalized with a single crown in the maxillary lateral incisor or mandibular central or lateral incisor area. Materials and methods: An open, prospective, single-cohort, multicenter study was conducted, in which narrow-diameter implants were placed in fresh, healed extraction, or congenitally missing sites. All patients were required to meet strict criteria for immediate loading. The primary endpoints were marginal bone levels (MBL) and MBL changes (MBLC) from implant placement to 5-year follow-up. Secondary endpoints included cumulative 5-year survival and success rates, soft tissue health, and esthetic parameters. Results: A total of 91 implants were placed in 77 patients. The mean MBL remained stable from the 1-year (− 0.79 ± 0.73 mm, n = 75) to 5-year (− 0.74 ± 0.87 mm, n = 65) follow-up. A marginal bone gain of 0.11 ± 0.83 mm was observed from the 1-year to 5-year follow-up. The cumulative 5-year survival rate was 96.5%, and the cumulative 5-year success rate was 93%. The clinical parameters, including the modified plaque index, modified sulcus bleeding index, Jemt’s papilla index, and pink esthetic score improved throughout the 5-year study. Conclusions: The study demonstrated that narrow-diameter implants represent a safe and predictable treatment option for subjects suitable for immediate loading and with limited bone volume or limited inter-dental space. Clinical relevance: Narrow-diameter implants with immediate provisionalization can be considered for use to restore missing or damaged teeth with predictable functional and esthetic outcomes. This trial was registered with ClinicalTrials.gov (NCT02184845). [ABSTRACT FROM AUTHOR]

In this article, a special type of fault isolation problem is reported where temporal information is required for the estimation of parameters from susceptible fault sub-space. Any physical system always obeys certain mathematical constraints under the normal operating condition, and that is incorporated in a behavioral model, which is essentially flowing and force or moment balance. In a fault detection and identification (FDI) model, only concurrent states are known. In FDI, the constraint relationships need to be derived only in terms of known variables, i.e., the measurements and nominal parameters, which are termed analytical redundancy relations (ARRs). The numerical evaluation of ARRs is residuals, and those oscillate within a definite bound of error when computed using test data. In this work, a novel function is formulated using the ARRs at different time instants and that function is minimized to estimate the suspected parameter values belonging to the non-isolable sub-space. Single-fault hypothesis is considered, and a genetic algorithm (GA) is used for the optimization. This FDI analysis may be beneficial for power hydraulic-driven heavy machinery such as hydraulic excavators, dumpers, and front-end loaders, which are mostly used in mines and construction sites. [ABSTRACT FROM AUTHOR]

This paper investigates hall sensor signal unbalancing faults in sensored Brushless Direct Current (BLDC) motor drives and presents a fault effect minimization scheme for implementation in motor controller without any modification in system architecture, or core commutation method. In the proposed scheme detection, classification, and estimation of fault extent are carried out separately at the start of controller itself for subsequent corrections without involving issue of repetitive error estimation and finding valid reference signal separately for correcting inverter switching mistiming, as required in classical methods. The categorization part of scheme maps the faults with corresponding hall sensors. The proposed scheme is validated in MATLAB/Simulink model. It is tested on experimental test bench of controller and 1 kW BLDC motor of an electric rickshaw, along with another technique based on least square method (LSM) for performance comparison. Results show reduction of peak-to-peak value by 30% and ripple content by 50% in phase currents, and peak-to-peak reduction of 47% with 29% lesser ripple content in DC link current by using the presented scheme. The observed increment in efficiency is 0.8% and 2% in nominal torque/ampere at 30% load. At 100% load, increase of 2.2% efficiency and 9% nominal torque/ampere are observed. The increased memory loading of controller is estimated to be 1.25 times as compared to normal run without any correction scheme. Approximately 24% of this additional loading is utilized for repetitive calculations as compared to 63% in the other LSM based scheme, resulting in lesser run time loading of controller. The transient response with sudden load change shows better response with implementation of the proposed scheme in controller. [ABSTRACT FROM AUTHOR]

The switched reluctance motor has numerous design parameters that must be selected properly to obtain high-speed and efficient motor design. Hence, it is mandatory to use an optimization model; however, the existing approaches selected design parameters with high loss. To reduce the losses and improve efficiency, an arithmetic optimization algorithm is used, which allows mathematical operators to solve the complex problem. The aim of optimization is to design a motor with high speed, maximum efficiency and maximum torque. Further, to investigate the overloading condition, the fractional-order proportional integral derivative controller is adopted. The simulated results show that the proposed design could be operated in high-speed applications with high efficiency and torque. From the analysis, the proposed method has improved the efficiency to 5.8% compared with the NSGA-II algorithm. [ABSTRACT FROM AUTHOR]

The torque ripple (TR) causes vibration in induction motor's shaft. This TR should be reduced to operate the induction motor drive safely. In this paper the modified torque comparator in direct torque control (DTC) scheme for three-phase induction motor is proposed to reduce the TR. The induction motor is fed with three-level neutral-point clamped (TLNPC) inverter so that the inverter gives more voltage vectors (VVs) as that of two level inverter. Due to the availability of more VVs, the DTC scheme can be implemented with modified five-level torque comparator (MFLTC). The MFLTC modifies the selection of VVs in a comparator both during incrementing and decrementing TR. The selection of VVs through MFLTC restricts the TR near the reference electromagnetic torque. The proposed DTC scheme also balances the dc link neutral point through alternately selection of positive and negative half VVs through MFLTC. To validate the proposed DTC method the simulation and experimental results are provided. [ABSTRACT FROM AUTHOR]

Purpose: To retrospectively evaluate peri-implant bone loss and health status associated with the long-term use of laser surface-treated implants. Methods: For control study, total of 23 titanium ASTM F136 grade 23 implants were placed in the edentulous molar area of the mandible. When the Implant Stability Quotient (ISQ) ≥ 70 and insertion torque value (ITV) ≥ 35–50 Ncm at the insertion site, an immediate provisional restoration was connected to the implant within a week after surgery. The definitive restorations were placed 2 months after surgery for all implants. 13 implants were immediately loaded, while 10 implants were conventionally loaded. For comparative study, Radiographs were taken from third years for and then annually for the subsequent eight years to monitor marginal bone loss. Results: After eight year of implant installation, the average change in vertical bone loss was 0.009 mm (P < 0.001), while the average change in horizontal bone loss 8 year after implant placement was 0.026 mm (P < 0.001). The mean marginal bone loss was < 0.2 mm on average. Conclusions: In this retrospective study, laser-treated implants exhibit a low rate of bone absorption around the implants. [ABSTRACT FROM AUTHOR]

This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing bearings. The methodology aims to overcome the limitations of state-of-the-art approaches, especially when the friction torque is conditioned by the preload of the balls. To this end, the authors propose to simulate the preload scatter when solving the load distribution problem, prior to the friction torque calculation. This preload scatter allows to simulate a progressive transition of the balls from a four-point contact state to a two-point contact one. By implementing this capability into an analytical model, the authors achieve a successful correlation with experimental results. Nonetheless, depending on the stiffness of the structures to which the bearing is assembled, it is demonstrated that the rigid ring assumption can lead to inaccurate friction torque results when a tilting moment is applied. The methodology described in this research work is meant to have a practical application. Therefore, the manuscript provides guidelines about how to use and tune the analytical model to get a reliable friction torque prediction tool. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Orofacial Orthopedics/Fortschritte der Kieferorthopadie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ducted-fan drones are expected to become the main drone configuration in the future due to their high efficiency and minimal noise. When drones operate in confined spaces, significant proximity effects may interfere with the aerodynamic performance and pose challenges to flight safety. This study utilizes computational fluid dynamics simulation with the Unsteady Reynolds-averaged Navier–Stokes (URANS) method to estimate the proximity effects. Through experimental validation, our computational results show that the influence range of proximity effects lies within four rotor radii. The ground effect and the ceiling effect mainly affect thrust properties, while the wall effect mainly affects the lateral force and the pitching moment. In ground effect, the rotor thrust increases exponentially by up to 26% with ground distance compared with that in open space. Minimum duct thrust and total thrust are observed at one rotor radius above the ground. In ceiling effect, all the thrusts rise as the drone approaches the ceiling, and total thrust increases by up to 19%. In wall effect, all the thrusts stay constant. The pitching moment and lateral force rise exponentially with the wall distance. Changes in blade angle of attack and duct pressure distributions can account for the performance change. The results are of great importance to the path planning and flight controller design of ducted-fan drones for safe and efficient operations in confined environments. [ABSTRACT FROM AUTHOR]

The magnet-less switched reluctance motor (SRM) speed-torque characteristics are ideally suited for traction motor drive characteristics and its advantage to minimize the overall cost of on-road EVs. The main drawbacks are torque and flux ripple, which have produced high in low-speed operation. However, the emerging direct torque control (DTC) operated magnitude flux and torque estimation with voltage vectors (VVs) gives high torque ripples due to the selection of effective switching states and sector partition accuracy. On the other hand, the existing model predictive control (MPC) with multiple objective and optimization weighting factors produces high torque ripples due to the system dynamics and constraints. Therefore, existing DTC and MPC can result in high torque ripples. This paper proposed a finite set (FS)-MPC with a single cost function objective without weighting factor: the predicted torque considered to evaluate VVs to minimize the ripples further. The selected optimal VV minimizes the SRM drive torque and flux ripples in steady and dynamic state behaviour. The classical DTC and proposed model were developed, and simulation results were verified using MATLAB/Simulink. The proposed model operated in SRM drives experimental results to prove the effective minimization of torque and flux ripples compared to the existing DTC. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to explore the spatial rotary movements of a symmetrically charged rigid body (RB) that is rotating around a fixed point, akin to Lagrange's scenario as a novel scenario where its center of mass experiences a slight displacement from the symmetry dynamic axis. The body's movement is presumed to be affected by a gyrostatic moment and a force from an electromagnetic field, attributed to the presence of a located point charge on this axis. The regulating equations of motion that are pertaining to the equations Euler–Poisson are solved through the utilization of Poincaré's small parameter method along with its adaptations when the scenario of irrational frequencies is considered. The three angles of Euler are derived and graphed to ascertain the body's position at any point throughout the motion. The temporal evolutions of the achieved outcomes are drawn to showcase the significant impact of the selected parameters on the motion. The phase plane diagrams have been generated to illustrate the stability of the body during the motion. The novelty of studying the rotatory motion of a charged RB under these specific conditions lies in the intricate interplay of gyrostatic effects, magnetic interactions, and nonlinear dynamics. This research can push the boundaries of theoretical mechanics and provide valuable insights and tools for both theoretical advancements and practical applications. Moreover, the achieved results from this analysis can be utilized to improve the dynamic performance of diverse engineering applications, particularly those dependent on gyroscopic theory. This includes enhancing the functionality of satellites, compasses, submarines, and automatic pilots used in aircraft. Essentially, the findings have practical implications for optimizing the performance and stability of these systems. [ABSTRACT FROM AUTHOR]

Purpose: The interpolated twitch technique (ITT) is often used to assess voluntary activation during isometric contractions; however, this may have limited relevance to dynamic contractions. Although the ITT has been applied to relatively slow isokinetic contractions (< 150°/s), it has received limited consideration during unconstrained velocity (i.e., isotonic) contractions, despite their relevance to natural movements. Here, we explored the ITT during isotonic knee extension contractions using a modified dynamometer. Methods: Young males (n = 6) and females (n = 4) performed isometric and isotonic knee extension contractions of sub-maximal and maximal intensities with doublet (150 Hz) muscle belly stimulations to assess voluntary activation. Following each voluntary isotonic contraction (velocity range ~ 35°/s to ~ 275°/s), resting potentiated doublets were evaluated during passive joint rotation at the same angular velocity achieved during voluntary efforts, to account for force–velocity characteristics. Correlations between voluntary activation and the proportion of maximal torque or power were evaluated for isometric and isotonic contractions, respectively. Results: Isometric voluntary activation was strongly correlated with increasing torque output (r = 0.96, p < 0.001). Doublet torque during passive joint rotation displayed a hyperbolic relationship with increasing angular velocity (r = 0.98, p < 0.001). Isotonic voluntary activation was strongly correlated with increasing power output (r = 0.89, p < 0.001). During maximal effort contractions, no differences were observed in voluntary activation between isometric and isotonic conditions (89.4% vs. 89.2%, p = 0.904). Conclusions: The ITT is a valid approach to evaluate voluntary activation during an isotonic contraction using a modified dynamometer. Participants were able to achieve a similar high level of voluntary activation during isometric and isotonic contractions. [ABSTRACT FROM AUTHOR]

An exact solution is obtained for a new class of problems on the imposition of large deformations in nonlinear elastic micropolar bodies. The problem of determining the stress state in a compound slab having the shape of a rectangular parallelepiped, composed of pre-deformed layers and subjected to biaxial tension or compression is solved. The layers are made of isotropic incompressible nonlinear elastic micropolar materials. The layers are preliminarily deformed by straightening of circular cylindrical sectors. The solution is based on a class of universal deformations for isotropic incompressible nonlinear elastic micropolar materials. Numerical studies were carried out. The dependencies of stresses, resulting forces and moments on the parameters of initial and additional deformations are presented. Significant nonlinear effects are revealed. The influence of micropolar effects on the stress state has been studied. The solution can be used to verify software designed to numerically solve problems on the imposition of large deformations in bodies made of nonlinear elastic micropolar materials. [ABSTRACT FROM AUTHOR]

Previous research reported reversal of the prototypical brain torque in individuals with mirrored visceral topology (situs inversus totalis, SIT). Here, we investigate if typical asymmetry of the posterior intracranial venous system is also reversed in SIT and whether the direction and magnitude of this asymmetry is related to the direction and magnitude of the brain torque. Brain structural MRI images of 38 participants with SIT were compared with those of 38 matched control participants. Occipital and frontal petalia and bending were measured using a standardized procedure. In addition, representative sections of the left and right transverse sinuses were segmented, and their respective volumes determined. Participants with SIT showed general reversal of occipital and frontal petalia and occipital bending, as well as reversal of typical transverse sinus asymmetry. Transverse sinus volume was significantly correlated with several torque measures, such that the smaller transverse sinus was associated with a larger ipsilateral occipital petalia, contralateral occipital bending, and ipsilateral frontal bending. We propose an anatomical mechanism to explain occipital petalia and bending, and conclude that anatomical constraints imposed by the asymmetry of the posterior venous system provide and additional account to elucidate the formation of the human brain torque. [ABSTRACT FROM AUTHOR]

We aimed to evaluate the screw-in force, torque generation, and performance of three nickel-titanium (NiTi) glide-path files with different rotational kinetics. ProTaper Ultimate Slider (PULS) and HyFlex EDM Glide-path (HEDG) files were used for canal shaping with constant rotation (CON) or the alternative rotation technique (ART). In the ART mode, the NiTi file was periodically rotated at a speed of 1.5 times faster than that in the CON mode. WaveOne Gold Glider was used with reciprocating motion (WOGG_RCP). Sixty J-shaped resin blocks were assigned to five groups: PULS_CON, PULS_ART, HEDG_CON, HEDG_ART, and WOGG_RCP (n = 12). Glide-path preparation was performed using an automated pecking device. During glide-path preparation, the screw-in force and clockwise and counterclockwise torques were recorded and the number of pecking motions required to reach the working length was determined. The centering ratio was calculated after glide-path preparation using stereomicroscopic images. Data were analyzed using one-way analysis of variance with the Games–Howell post hoc test and the Kruskal–Wallis test with Bonferroni correction. PULS_ART generated a lower maximum screw-in force than PULS_CON. The average number of pecking motions required to reach the working length by HEDG_ART was lower than that by HEDG_CON. The mean centering ratios of PULS_CON and HEDG_CON were − 0.04 and − 0.06, respectively, while those of PULS_ART, HEDG_ART, and WOGG_RCP were 0.09, 0.01, and 0.08, respectively. The ART mode reduced the screw-in force of PULS and enabled faster glide-path preparation with the HEDG file. [ABSTRACT FROM AUTHOR]