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Sample records for spike-triggered average torque

  1. The pain-induced decrease in low-threshold motor unit discharge rate is not associated with the amount of increase in spike-triggered average torque.

    Science.gov (United States)

    Farina, Dario; Arendt-Nielsen, Lars; Roatta, Silvestro; Graven-Nielsen, Thomas

    2008-01-01

    Activation of nociceptive afferents decreases motor unit discharge rates in static contractions. There is also evidence that during experimental muscle pain the motor unit twitch force increases, which has been hypothesized to compensate for the decrease in discharge rate to maintain constant force. This study examined whether there is an association between the magnitude of change in motor unit discharge rate and the amount of increase in the spike-triggered average torque during experimental muscle pain. Sixteen subjects performed three constant-torque isometric ankle dorsi-flexions at 10% of the maximal force (MVC) alternated with two contractions at constant discharge rate of a target motor unit, before and following injection of 0.5 ml of hypertonic (painful) or isotonic (control) saline into the tibialis anterior muscle. The discharge rate of the target unit at 10% MVC decreased following injection of hypertonic saline (P<0.05; mean+/-SD, before: 9.9+/-1.3 pulses per second, pps; after injection: 8.9+/-1.0 pps). The peak of the spike-triggered average torque increased with pain (P<0.05; before: 0.56+/-0.55 mNm; during pain: 0.95+/-1.02 mNm) but the increase was not correlated with the decrease in discharge rate (R=0.08). Propagation velocity and action potential peak-to-peak amplitude did not change with pain. The pain-induced modifications in the estimated motor unit twitch torque (1) were not caused by changes in muscle fiber action potential, and (2) were not associated with the decrease in discharge rate. Maintenance of constant force during static painful contractions is not explained by a matching between changes in contractile and control motor unit properties.

  2. Sympathetic-induced changes in discharge rate and spike-triggered average twitch torque of low-threshold motor units in humans.

    Science.gov (United States)

    Roatta, Silvestro; Arendt-Nielsen, Lars; Farina, Dario

    2008-11-15

    Animal and in vitro studies have shown that the sympathetic nervous system modulates the contractility of skeletal muscle fibres, which may require adjustments in the motor drive to the muscle in voluntary contractions. In this study, these mechanisms were investigated in the tibialis anterior muscle of humans during sympathetic activation induced by the cold pressor test (CPT; left hand immersed in water at 4 degrees C). In the first experiment, 11 healthy men performed 20 s isometric contractions at 10% of the maximal torque, before, during and after the CPT. In the second experiment, 12 healthy men activated a target motor unit at the minimum stable discharge rate for 5 min in the same conditions as in experiment 1. Intramuscular electromyographic (EMG) signals and torque were recorded and used to assess the motor unit discharge characteristics (experiment 1) and spike-triggered average twitch torque (experiment 2). CPT increased the diastolic blood pressure and heart rate by (mean +/- S.D.) 18 +/- 9 mmHg and 4.7 +/- 6.5 beats min(-1) (P < 0.01), respectively. In experiment 1, motor unit discharge rate increased from 10.4 +/- 1.0 pulses s(-1) before to 11.1 +/- 1.4 pulses s(-1) (P < 0.05) during the CPT. In experiment 2, the twitch half-relaxation time decreased by 15.8 +/- 9.3% (P < 0.05) during the CPT with respect to baseline. These results provide the first evidence of an adrenergic modulation of contractility of muscle fibres in individual motor units in humans, under physiological sympathetic activation.

  3. Limitations of the spike-triggered averaging for estimating motor unit twitch force: a theoretical analysis.

    Directory of Open Access Journals (Sweden)

    Francesco Negro

    Full Text Available Contractile properties of human motor units provide information on the force capacity and fatigability of muscles. The spike-triggered averaging technique (STA is a conventional method used to estimate the twitch waveform of single motor units in vivo by averaging the joint force signal. Several limitations of this technique have been previously discussed in an empirical way, using simulated and experimental data. In this study, we provide a theoretical analysis of this technique in the frequency domain and describe its intrinsic limitations. By analyzing the analytical expression of STA, first we show that a certain degree of correlation between the motor unit activities prevents an accurate estimation of the twitch force, even from relatively long recordings. Second, we show that the quality of the twitch estimates by STA is highly related to the relative variability of the inter-spike intervals of motor unit action potentials. Interestingly, if this variability is extremely high, correct estimates could be obtained even for high discharge rates. However, for physiological inter-spike interval variability and discharge rate, the technique performs with relatively low estimation accuracy and high estimation variance. Finally, we show that the selection of the triggers that are most distant from the previous and next, which is often suggested, is not an effective way for improving STA estimates and in some cases can even be detrimental. These results show the intrinsic limitations of the STA technique and provide a theoretical framework for the design of new methods for the measurement of motor unit force twitch.

  4. Limitations of the Spike-Triggered Averaging for Estimating Motor Unit Twitch Force: A Theoretical Analysis

    Science.gov (United States)

    Negro, Francesco; Yavuz, Utku Ş.; Farina, Dario

    2014-01-01

    Contractile properties of human motor units provide information on the force capacity and fatigability of muscles. The spike-triggered averaging technique (STA) is a conventional method used to estimate the twitch waveform of single motor units in vivo by averaging the joint force signal. Several limitations of this technique have been previously discussed in an empirical way, using simulated and experimental data. In this study, we provide a theoretical analysis of this technique in the frequency domain and describe its intrinsic limitations. By analyzing the analytical expression of STA, first we show that a certain degree of correlation between the motor unit activities prevents an accurate estimation of the twitch force, even from relatively long recordings. Second, we show that the quality of the twitch estimates by STA is highly related to the relative variability of the inter-spike intervals of motor unit action potentials. Interestingly, if this variability is extremely high, correct estimates could be obtained even for high discharge rates. However, for physiological inter-spike interval variability and discharge rate, the technique performs with relatively low estimation accuracy and high estimation variance. Finally, we show that the selection of the triggers that are most distant from the previous and next, which is often suggested, is not an effective way for improving STA estimates and in some cases can even be detrimental. These results show the intrinsic limitations of the STA technique and provide a theoretical framework for the design of new methods for the measurement of motor unit force twitch. PMID:24667744

  5. Dimensionality reduction in neural models: an information-theoretic generalization of spike-triggered average and covariance analysis.

    Science.gov (United States)

    Pillow, Jonathan W; Simoncelli, Eero P

    2006-04-28

    We describe an information-theoretic framework for fitting neural spike responses with a Linear-Nonlinear-Poisson cascade model. This framework unifies the spike-triggered average (STA) and spike-triggered covariance (STC) approaches to neural characterization and recovers a set of linear filters that maximize mean and variance-dependent information between stimuli and spike responses. The resulting approach has several useful properties, namely, (1) it recovers a set of linear filters sorted according to their informativeness about the neural response; (2) it is both computationally efficient and robust, allowing recovery of multiple linear filters from a data set of relatively modest size; (3) it provides an explicit "default" model of the nonlinear stage mapping the filter responses to spike rate, in the form of a ratio of Gaussians; (4) it is equivalent to maximum likelihood estimation of this default model but also converges to the correct filter estimates whenever the conditions for the consistency of STA or STC analysis are met; and (5) it can be augmented with additional constraints on the filters, such as space-time separability. We demonstrate the effectiveness of the method by applying it to simulated responses of a Hodgkin-Huxley neuron and the recorded extracellular responses of macaque retinal ganglion cells and V1 cells.

  6. Cortical plasticity induced by spike-triggered microstimulation in primate somatosensory cortex.

    Directory of Open Access Journals (Sweden)

    Weiguo Song

    Full Text Available Electrical stimulation of the nervous system for therapeutic purposes, such as deep brain stimulation in the treatment of Parkinson's disease, has been used for decades. Recently, increased attention has focused on using microstimulation to restore functions as diverse as somatosensation and memory. However, how microstimulation changes the neural substrate is still not fully understood. Microstimulation may cause cortical changes that could either compete with or complement natural neural processes, and could result in neuroplastic changes rendering the region dysfunctional or even epileptic. As part of our efforts to produce neuroprosthetic devices and to further study the effects of microstimulation on the cortex, we stimulated and recorded from microelectrode arrays in the hand area of the primary somatosensory cortex (area 1 in two awake macaque monkeys. We applied a simple neuroprosthetic microstimulation protocol to a pair of electrodes in the area 1 array, using either random pulses or pulses time-locked to the recorded spiking activity of a reference neuron. This setup was replicated using a computer model of the thalamocortical system, which consisted of 1980 spiking neurons distributed among six cortical layers and two thalamic nuclei. Experimentally, we found that spike-triggered microstimulation induced cortical plasticity, as shown by increased unit-pair mutual information, while random microstimulation did not. In addition, there was an increased response to touch following spike-triggered microstimulation, along with decreased neural variability. The computer model successfully reproduced both qualitative and quantitative aspects of the experimental findings. The physiological findings of this study suggest that even simple microstimulation protocols can be used to increase somatosensory information flow.

  7. Inference of neuronal functional circuitry with spike-triggered non-negative matrix factorization.

    Science.gov (United States)

    Liu, Jian K; Schreyer, Helene M; Onken, Arno; Rozenblit, Fernando; Khani, Mohammad H; Krishnamoorthy, Vidhyasankar; Panzeri, Stefano; Gollisch, Tim

    2017-07-26

    Neurons in sensory systems often pool inputs over arrays of presynaptic cells, giving rise to functional subunits inside a neuron's receptive field. The organization of these subunits provides a signature of the neuron's presynaptic functional connectivity and determines how the neuron integrates sensory stimuli. Here we introduce the method of spike-triggered non-negative matrix factorization for detecting the layout of subunits within a neuron's receptive field. The method only requires the neuron's spiking responses under finely structured sensory stimulation and is therefore applicable to large populations of simultaneously recorded neurons. Applied to recordings from ganglion cells in the salamander retina, the method retrieves the receptive fields of presynaptic bipolar cells, as verified by simultaneous bipolar and ganglion cell recordings. The identified subunit layouts allow improved predictions of ganglion cell responses to natural stimuli and reveal shared bipolar cell input into distinct types of ganglion cells.How a neuron integrates sensory information requires knowledge about its functional presynaptic connections. Here the authors report a new method using non-negative matrix factorization to identify the layout of presynaptic bipolar cell inputs onto retinal ganglion cells and predict their responses to natural stimuli.

  8. Spike-Triggered Regression for Synaptic Connectivity Reconstruction in Neuronal Networks.

    Science.gov (United States)

    Zhang, Yaoyu; Xiao, Yanyang; Zhou, Douglas; Cai, David

    2017-01-01

    How neurons are connected in the brain to perform computation is a key issue in neuroscience. Recently, the development of calcium imaging and multi-electrode array techniques have greatly enhanced our ability to measure the firing activities of neuronal populations at single cell level. Meanwhile, the intracellular recording technique is able to measure subthreshold voltage dynamics of a neuron. Our work addresses the issue of how to combine these measurements to reveal the underlying network structure. We propose the spike-triggered regression (STR) method, which employs both the voltage trace and firing activity of the neuronal population to reconstruct the underlying synaptic connectivity. Our numerical study of the conductance-based integrate-and-fire neuronal network shows that only short data of 20 ~ 100 s is required for an accurate recovery of network topology as well as the corresponding coupling strength. Our method can yield an accurate reconstruction of a large neuronal network even in the case of dense connectivity and nearly synchronous dynamics, which many other network reconstruction methods cannot successfully handle. In addition, we point out that, for sparse networks, the STR method can infer coupling strength between each pair of neurons with high accuracy in the absence of the global information of all other neurons.

  9. Casimir torque

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Guzman, Jose C [Centro de Ciencias FIsicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Mochan, W Luis [Centro de Ciencias FIsicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico)

    2006-05-26

    We develop a formalism for the calculation of the flow of angular momentum carried by the fluctuating electromagnetic field within a cavity bounded by two flat anisotropic materials. By generalizing a procedure employed recently for the calculation of the Casimir force between arbitrary materials, we obtain an expression for the torque between anisotropic plates in terms of their reflection amplitude matrices. We evaluate the torque in 1D for ideal and dispersive model materials.

  10. Muscle response to pneumatic hand tool torque reaction forces.

    Science.gov (United States)

    Radwin, R G; VanBergeijk, E; Armstrong, T J

    1989-06-01

    Surface electromyography was used for studying the effects of torque reaction force acting against the hand, on forearm muscle activity and grip force for five subjects operating right angle, air shut-off nutrunners. Four tools having increasing spindle torque were operated using short and long torque reaction times. Nutrunner spindle torque ranged between 30 Nm and 100 Nm. Short torque reaction time was considered 0.5 s while long torque reaction time was 2 s. Peak horizontal force was the greatest component of the reaction force acting against the hand and accounted for more than 97% of the peak resultant hand force. Peak hand force increased from 89 N for the smallest tool to 202 N for the largest tool. Forearm muscle rms EMG, scaled for grip force, indicated average flexor activity during the Torque-reaction phase was more than four times greater than the Pre-start and Post Shut-off phases, and two times greater than the Run-down phase. Flexor EMG activity during the Torque-reaction phase increased for increasing tool peak spindle torque. Average flexor rms EMG activity, scaled for grip force, during the Torque-reaction phase increased from 372 N for the 30 Nm nutrunner to 449 N for the 100 Nm nutrunner. Flexor rms EMG activity averaged during the Torque-reaction phase and scaled for grip force was 390 N for long torque reaction times and increased to 440 N for short torque reaction times. Flexor rms EMG integrated over the torque reaction phase was 839 Ns for long torque reaction times and decreased to 312 Ns for short torque reaction times. The average latency between tool spindle torque onset and peak initial flexor rms EMG for long torque reaction times was 294 ms which decreased to 161 ms for short torque reaction times. The average latency between peak tool spindle torque, just prior to tool shut-off, and peak final rms EMG for long torque reaction times was 97 ms for flexors and 188 ms for extensors, which decreased for short torque reaction times to 47

  11. Robust estimation of average twitch contraction forces of populations of motor units in humans.

    Science.gov (United States)

    Negro, Francesco; Orizio, Claudio

    2017-12-01

    The characteristics of motor unit force twitch profiles provide important information for the understanding of the muscle force generation. The twitch force is commonly estimated with the spike-triggered averaging technique, which, despite the many limitations, has been important for clarifying central issues in force generation. In this study, we propose a new technique for the estimation of the average twitch profile of populations of motor units with uniform contractile properties. The method encompasses a model-based deconvolution of the force signal using the identified discharge times of a population of motor units. The proposed technique was validated using simulations and tested on signals recorded during voluntary activation. The results of the simulations showed that the proposed method provides accurate estimates (relative error twitch force when the number of identified motor units is between 5% and 15% of the total number of active motor units. It is discussed that current detection and decomposition methods of multi-channel surface EMG signals allow decoding this relative sample of the active motor unit pool. However, even when this condition is not met, our results show that the estimates provided by the new method are anyway always superior to those obtained by the spike triggered average approach, especially for high motor unit synchronization levels and when a relatively small number of triggers is available. In conclusion, we present a new method that overcome the main limitations of the spike-triggered average for the study of contractile properties of individual motor units. The method provides a new reliable tool for the investigation of the determinants of muscle force. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Torque ripple reduction in direct torque controlled five-phase ...

    Indian Academy of Sciences (India)

    The five-phase induction motor inherently has the minimal torque ripple. However, when it is controlled by direct torque control (DTC) technique, the torque ripple increases due to the presence of a hysteresis torque comparator. The classical five-level torque comparator is presented in the previous literatures to control the ...

  13. Angular Acceleration without Torque?

    Science.gov (United States)

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

  14. State Averages

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of a variety of averages for each state or territory as well as the national average, including each quality measure, staffing, fine amount and number of...

  15. Torque and optical traps

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-29

    Dec 29, 2008 ... Optical traps are an important tool for research in the field of single molecule biophysics. Recent advances in optical trapping have extended their functionality from simple linear manipulation and measurement of forces, to now the ability to rotate objects and measure torques. This mini review summarizes ...

  16. Spin-torque transistor

    NARCIS (Netherlands)

    Bauer, G.E.W.; Brataas, A.; Tserkovnyak, Y.; Van Wees, B.J.

    2003-01-01

    A magnetoelectronic thin-film transistor is proposed that can display negative differential resistance and gain. The working principle is the modulation of the soure–drain current in a spin valve by the magnetization of a third electrode, which is rotated by the spin-torque created by a control spin

  17. Magnon-mediated Dzyaloshinskii-Moriya torque in homogeneous ferromagnets

    KAUST Repository

    Manchon, Aurelien

    2014-12-01

    In thin magnetic layers with structural inversion asymmetry and spin-orbit coupling, the Dzyaloshinskii-Moriya interaction arises at the interface. When a spin-wave current jm flows in a system with a homogeneous magnetization m, this interaction produces an effective fieldlike torque of the form TFLm×(z×jm) as well as a dampinglike torque, TDLm×[(z×jm)×m], the latter only in the presence of spin-wave relaxation (z is normal to the interface). These torques mediated by the magnon flow can reorient the time-averaged magnetization direction and display a number of similarities with the torques arising from the electron flow in a magnetic two-dimensional electron gas with Rashba spin-orbit coupling. This magnon-mediated spin-orbit torque can be efficient in the case of magnons driven by a thermal gradient.

  18. Butterfly valve torque prediction methodology

    International Nuclear Information System (INIS)

    Eldiwany, B.H.; Sharma, V.; Kalsi, M.S.; Wolfe, K.

    1994-01-01

    As part of the Motor-Operated Valve (MOV) Performance Prediction Program, the Electric Power Research Institute has sponsored the development of methodologies for predicting thrust and torque requirements of gate, globe, and butterfly MOVs. This paper presents the methodology that will be used by utilities to calculate the dynamic torque requirements for butterfly valves. The total dynamic torque at any disc position is the sum of the hydrodynamic torque, bearing torque (which is induced by the hydrodynamic force), as well as other small torque components (such as packing torque). The hydrodynamic torque on the valve disc, caused by the fluid flow through the valve, depends on the disc angle, flow velocity, upstream flow disturbances, disc shape, and the disc aspect ratio. The butterfly valve model provides sets of nondimensional flow and torque coefficients that can be used to predict flow rate and hydrodynamic torque throughout the disc stroke and to calculate the required actuation torque and the maximum transmitted torque throughout the opening and closing stroke. The scope of the model includes symmetric and nonsymmetric discs of different shapes and aspects ratios in compressible and incompressible fluid applications under both choked and nonchoked flow conditions. The model features were validated against test data from a comprehensive flowloop and in situ test program. These tests were designed to systematically address the effect of the following parameters on the required torque: valve size, disc shapes and disc aspect ratios, upstream elbow orientation and its proximity, and flow conditions. The applicability of the nondimensional coefficients to valves of different sizes was validated by performing tests on 42-in. valve and a precisely scaled 6-in. model. The butterfly valve model torque predictions were found to bound test data from the flow-loop and in situ testing, as shown in the examples provided in this paper

  19. Accurate torque-speed performance prediction for brushless dc motors

    Science.gov (United States)

    Gipper, Patrick D.

    Desirable characteristics of the brushless dc motor (BLDCM) have resulted in their application for electrohydrostatic (EH) and electromechanical (EM) actuation systems. But to effectively apply the BLDCM requires accurate prediction of performance. The minimum necessary performance characteristics are motor torque versus speed, peak and average supply current and efficiency. BLDCM nonlinear simulation software specifically adapted for torque-speed prediction is presented. The capability of the software to quickly and accurately predict performance has been verified on fractional to integral HP motor sizes, and is presented. Additionally, the capability of torque-speed prediction with commutation angle advance is demonstrated.

  20. Manual Torque Data Study

    Energy Technology Data Exchange (ETDEWEB)

    Mundt, Mark Osroe [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Matthew Ronald [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Varela, Jeanette Judith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderson-Cook, Christine Michaela [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gilmore, Walter E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Williams, Allie [Pantex Plant (PTX), Amarillo, TX (United States)

    2018-01-11

    At the Pantex Plant in Amarillo, TX, Production Technicians (PTs) build and disassemble nuclear weapon systems. The weapons are held in an integrated work stand for stability and to increase the safety environment for the workers and for the materials being processed. There are many occasions in which a knob must be turned to tighten an assembly part. This can help to secure or manipulate pieces of the system. As there are so many knobs to turn, the instructions given to the PTs are to twist the knob to a hand-tight setting, without the aid of a torque wrench. There are inherent risks in this procedure as the knobs can be tightened too loosely such that the apparatus falls apart or too tightly such that the force can crush or pinch components in the system that contain energetic materials. We want to study these operations at Pantex. Our goal is to collect torque data to assess the safety and reliability of humantooling interfaces.

  1. Design of a lightweight, tethered, torque-controlled knee exoskeleton.

    Science.gov (United States)

    Witte, Kirby Ann; Fatschel, Andreas M; Collins, Steven H

    2017-07-01

    Lower-limb exoskeletons show promise for improving gait rehabilitation for those with chronic gait abnormalities due to injury, stroke or other illness. We designed and built a tethered knee exoskeleton with a strong lightweight frame and comfortable, four-point contact with the leg. The device is structurally compliant in select directions, instrumented to measure joint angle and applied torque, and is lightweight (0.76 kg). The exoskeleton is actuated by two off-board motors. Closed loop torque control is achieved using classical proportional feedback control with damping injection in conjunction with iterative learning. We tested torque measurement accuracy and found root mean squared (RMS) error of 0.8 Nm with a max load of 62.2 Nm. Bandwidth was measured to be phase limited at 45 Hz when tested on a rigid test stand and 23 Hz when tested on a person's leg. During bandwidth tests peak extension torques were measured up to 50 Nm. Torque tracking was tested during walking on a treadmill at 1.25 m/s with peak flexion torques of 30 Nm. RMS torque tracking error averaged over a hundred steps was 0.91 Nm. We intend to use this knee exoskeleton to investigate robotic assistance strategies to improve gait rehabilitation and enhance human athletic ability.

  2. [Influence of slot size on torque control].

    Science.gov (United States)

    Tian, Jun; Liu, Zhong-Hao; Zhang, Ding; Wu, Chuan-Jun

    2009-12-01

    To study the influence of two slot size brackets on torque control when teeth interacted in the same arch. After the upper arch was aligned and leveled in Typodont study, the inclinations of upper teeth 5 +/- 5 were measured when 0.457 2 mm x 0.635 0 mm OPA-K brackets and 0.558 8 mmx0.711 2 mm OPA-K brackets were filled with 0.431 8 mm x 0.635 0 mm stainless steel wire. This experiment was duplicated 10 times. The inclin of each tooth were transformed to the absolute values of the torque play angle psi by computing program, and paired-t test was used. The two kinds of slot size brackets were different with statistical significance on torque control. When the brackets were filled with 0.431 8 mm x 0.635 0 mm stainless steel wire, the absolute values of the angle psi in 0.558 8 mm x 0.711 2 mm and 0.457 2 mm x 0.635 0 mm slot size brackets were 6.140 degrees +/- 3.758 degrees and 2.608 degrees +/- 1.479 degrees respectively, and the average difference of that between the two slot size brackets was 3.532 degrees. The absolute values of the angle psi in the upper left and right canine brackets were 2.560 degrees +/- 2.605 degrees, 4.230 degrees +/- 2.817 degrees, 1.260 degrees +/- 0.747 degrees and 2.070 degrees +/- 0.663 degrees respectively, and average differences between them were smaller than that in the other teeth. There was difference between the two kinds of slot size brackets on torque control, and 0.457 2 mm x 0.635 0 mm slot size bracket controls torque better when filled with the same size wire. In this study, the teeth interaction in the same arch probably caused the result that the difference of two slot size brackets on torque control was less than the study results of the theory calculations and material studys before.

  3. Excitation and Transmitted Torque

    Directory of Open Access Journals (Sweden)

    H. B. H. Gubran

    2000-01-01

    Full Text Available In the present study, stress analysis of fiber reinforced thin composite shafts subjected to unbalance excitation and steady torque, is carried out. Shafts of uniform as well as variable wall thickness are considered. The shaft is modeled as a simply supported Timoshenko beam in which shear deformation, rotary inertia and gyroscopic effects have been included. Modified equivalent modulus beam theory has been adopted. Rayleigh-Ritz displacements are used for deriving the solution equations. Shafts with a uniform wall thickness, and with variable wall thickness in which the thickness is varied along the axial length of the shaft for three different cases of fiber angles have been studied. Axial variation of stresses is studied in detail. Results obtained indicate that the stresses in the variable wall thickness are smaller than the one with uniform wall thickness, even for the same weight of the shaft.

  4. Hybrid synchronous motor electromagnetic torque research

    Directory of Open Access Journals (Sweden)

    Suvorkova Elena E.

    2014-01-01

    Full Text Available Electromagnetic field distribution models in reluctance and permanent magnet parts were made by means of Elcut. Dependences of electromagnetic torque on torque angle were obtained.

  5. Zero torque gear head wrench

    Science.gov (United States)

    Mcdougal, A. R.; Norman, R. M. (Inventor)

    1976-01-01

    A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed.

  6. Torque-Summing Brushless Motor

    Science.gov (United States)

    Vaidya, J. G.

    1986-01-01

    Torque channels function cooperatively but electrically independent for reliability. Brushless, electronically-commutated dc motor sums electromagnetic torques on four channels and applies them to single shaft. Motor operates with any combination of channels and continues if one or more of channels fail electrically. Motor employs single stator and rotor and mechanically simple; however, each of channels electrically isolated from other so that failure of one does not adversely affect others.

  7. 14 CFR 27.361 - Engine torque.

    Science.gov (United States)

    2010-01-01

    ... turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for maximum... compressor jamming). (b) For reciprocating engines, the limit torque may not be less than the mean torque for maximum continuous power multiplied by— (1) 1.33, for engines with five or more cylinders; and (2) Two...

  8. Electrical torques on the electrostatic gyro in the gyro relativity experiment

    Science.gov (United States)

    Eby, P.; Darbo, W.

    1980-10-01

    A comprehensive discussion and calculation of electrical torques on an electrostatic gyro as they relate to the gyroscope experiment to test general relativity is presented. Drift rates were computed for some typical state of the art rotors, including higher harmonics in the rotor shape. The effect of orbital averaging of gravity gradient forces, roll averaging of torques, and the effect of spin averaging on the effective shape of the rotor were considered. The electrical torques are reduced sufficiently in a low g environment to permit a measurement of the relativistic drifts predicted by general relativity.

  9. Torque ripple reduction in direct torque controlled five-phase ...

    Indian Academy of Sciences (India)

    Yogesh Tatte

    MS received 4 May 2016; revised 25 April 2017; accepted 3 June 2017; published online 7 February 2018. Abstract. ...... The data and parameters of the machine are depicted in table 3. Figures 6 and 7 summarize the performance of five- phase IM controlled by DTC method with the classical five- level torque comparator ...

  10. Mechanomyography and Torque during FES-Evoked Muscle Contractions to Fatigue in Individuals with Spinal Cord Injury

    Science.gov (United States)

    Mohamad, Nor Zainah; Hamzaid, Nur Azah; Abdul Wahab, Ahmad Khairi; Hasnan, Nazirah

    2017-01-01

    A mechanomyography muscle contraction (MC) sensor, affixed to the skin surface, was used to quantify muscle tension during repetitive functional electrical stimulation (FES)-evoked isometric rectus femoris contractions to fatigue in individuals with spinal cord injury (SCI). Nine persons with motor complete SCI were seated on a commercial muscle dynamometer that quantified peak torque and average torque outputs, while measurements from the MC sensor were simultaneously recorded. MC-sensor-predicted measures of dynamometer torques, including the signal peak (SP) and signal average (SA), were highly associated with isometric knee extension peak torque (SP: r = 0.91, p torque (SA: r = 0.89, p muscle torques (SP; ρC = 0.91) and average muscle torques (SA; ρC = 0.89) with the equivalent dynamometer measures, over a range of FES current amplitudes. The relationship of dynamometer torques and predicted MC torques during repetitive FES-evoked muscle contraction to fatigue were moderately associated (SP: r = 0.80, p muscle mechanomyography sensor was an accurate proxy for electrically-evoked muscle contraction torques when directly measured during isometric dynamometry in individuals with SCI. The novel application of the MC sensor during FES-evoked muscle contractions suggested its possible application for real-world tasks (e.g., prolonged sit-to-stand, stepping,) where muscle forces during fatiguing activities cannot be directly measured. PMID:28708068

  11. Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers

    Science.gov (United States)

    Pease, Christopher; Etheridge, J.; Wijesinghe, H. S.; Pierce, C. J.; Prikockis, M. V.; Sooryakumar, R.

    Chains of micro-magnetic particles are often rotated with external magnetic fields for many lab-on-a-chip technologies such as transporting beads or mixing fluids. These applications benefit from faster responses of the actuated particles. In a rotating magnetic field, the magnetization of superparamagnetic beads, created from embedded magnetic nano-particles within a polymer matrix, is largely characterized by induced dipoles mip along the direction of the field. In addition there is often a weak dipole mop that orients out-of-phase with the external rotating field. On a two-bead dimer, the simplest chain of beads, mop contributes a torque Γm in addition to the torque from mip. For dimers with beads unbound to each other, mop rotates individual beads which generate an additional hydrodynamic torque on the dimer. Whereas, mop directly torques bound dimers. Our results show that Γm significantly alters the average frequency-dependent dimer rotation rate for both bound and unbound monomers and, when mop exceeds a critical value, increases the maximum dimer rotation frequency. Models that include magnetic and hydrodynamics torques provide good agreement with the experimental findings over a range of field frequencies.

  12. Apply of torque method at rationalization of work

    Directory of Open Access Journals (Sweden)

    Bandurová Miriam

    2001-03-01

    Full Text Available Aim of the study was to analyse consumption of time for profession - cylinder grinder, by torque method.Method of torque following is used for detection of sorts and size of time slope, on detection of portion of individual sorts of time consumption and cause of time slope. By this way it is possible to find out coefficient of employment and recovery of workers in organizational unit. Advantage of torque survey is low costs on informations acquirement, non-fastidiousness per worker and observer, which is easy trained. It is mentally acceptable method for objects of survey.Finding and detection of reserves in activity of cylinders grinder result of torque was surveys. Loss of time presents till 8% of working time. In 5 - shift service and average occupiying of shift by 4,4 grinder ( from statistic information of service , loss at grinder of cylinders are for whole centre 1,48 worker.According presented information it was recommended to cancel one job place - grinder of cylinders - and reduce state about one grinder. Next job place isn't possible cancel, because grindery of cylinders must to adapt to the grind line by number of polished cylinders in shift and semi - finishing of polished cylinders can not be high for often changes in area of grinding and sortiment changes.By this contribution we confirmed convenience of exploitation of torque method as one of the methods using during the job rationalization.

  13. Toroidal field coil torque structure

    International Nuclear Information System (INIS)

    Gaines, A.L.

    1983-01-01

    A torque structure is disclosed particularly suitable for utilization in a power reactor of the Tokamak-type, and operable therein for purposes of providing support for the toroidal field (TF) coils that comprise one of the major operating components of such a Tokamak power reactor. The subject torque structure takes the form of a frame structure that is operable to enable torque loads acting on the TF coils to be equilibrated as close to the area of force application as feasible. The aforesaid torque structure includes an intercoil structure composed of spacer wedges that are interposed between each adjacent pair of TF coils. The spacer wedges, in turn, consist of bearing plates positioned between the TF coils so as to be in contacting relation therewith and a number of cross plates that are cooperatively associated with the bearing plates so as to form therewith a rigid assembly. The intercoil structure is affixed to a segmented, membrane shell that surrounds, encloses and supports the TF coil frames. Access is had to the interior of the shell through an opening formed for this purpose in a reinforced portion of the shell. Eddy current losses are minimized by insulating the joints formed at the juncture of adjoining segments of the shell

  14. 14 CFR 29.361 - Engine torque.

    Science.gov (United States)

    2010-01-01

    ... mean torque for maximum continuous power multiplied by 1.25; (2) The torque required by § 29.923; (3... for maximum continuous power multiplied by— (1) 1.33, for engines with five or more cylinders; and (2...

  15. Computerized Torque Control for Large dc Motors

    Science.gov (United States)

    Willett, Richard M.; Carroll, Michael J.; Geiger, Ronald V.

    1987-01-01

    Speed and torque ranges in generator mode extended. System of shunt resistors, electronic switches, and pulse-width modulation controls torque exerted by large, three-phase, electronically commutated dc motor. Particularly useful for motor operating in generator mode because it extends operating range to low torque and high speed.

  16. Calibration of the optical torque wrench

    NARCIS (Netherlands)

    Pedaci, F.; Huang, Z.; Van Oene, M.; Dekker, N.H.

    2012-01-01

    The optical torque wrench is a laser trapping technique that expands the capability of standard optical tweezers to torque manipulation and measurement, using the laser linear polarization to orient tailored microscopic birefringent particles. The ability to measure torque of the order of kBT (?4 pN

  17. Measuring the uncertainty of tapping torque

    DEFF Research Database (Denmark)

    Belluco, Walter; De Chiffre, Leonardo

    An uncertainty budget is carried out for torque measurements performed at the Institut for Procesteknik for the evaluation of cutting fluids. Thirty test blanks were machined with one tool and one fluid, torque diagrams were recorded and the repeatability of single torque measurements was estimat...

  18. Comparison of three-level torque hysteresis controllers for direct torque control

    OpenAIRE

    Beerten, Jef; Verveckken, Jan; Driesen, Johan

    2009-01-01

    In this paper, a comparison is made between different implementations of the three-level torque comparator for a Direct Torque Control (DTC) based induction motor drive. The DTC scheme controls stator flux and torque by means of hysteresis comparators, respectively a two-level control structure for the stator flux and a three-level comparator for the electromagnetic torque. The standard three-level hysteresis controller has a DC offset torque error. In this paper, an additive implementation i...

  19. Electrically Elicited Quadriceps Muscle Torque: A Comparison of 3 Waveforms.

    Science.gov (United States)

    Adams, Cheryl; Scott, Wayne; Basile, Jonathan; Hughes, Lorraine; Leigh, Joshua; Schiller, Anna; Walton, Jeffrey

    2018-03-01

    Study Design A controlled laboratory study, with a single-blind, block-randomization crossover design. Objectives To compare the electrically elicited knee extensor torque produced by 3 clinically available waveforms: 2500-Hz burst-modulated alternating current (BMAC), 1000-Hz BMAC, and 1000-Hz burst-modulated biphasic square-wave pulsed current (BMBPC). Background Neuromuscular electrical stimulation (NMES) is the therapeutic use of electrical current to strengthen muscle. Muscle torque produced by NMES is limited by discomfort. Methods The knee extensor maximal volitional isometric torque (KEMVIT) of 33 able-bodied participants (18 female) was measured and used to normalize the electrically elicited knee extensor torque to produce a percent of KEMVIT (%KEMVIT). Electrically elicited isometric knee extensor torque was measured in response to each of the waveforms at the participants' maximum tolerance. Results The average maximum tolerated stimulation produced 32.0 ± 16.7 %KEMVIT with 2500-Hz BMAC, 38.2 ± 18.4 %KEMVIT with 1000-Hz BMAC, and 42.2 ± 17.1 %KEMVIT with 1000-Hz BMBPC. Tukey honest significant difference (HSD) post hoc testing revealed a statistically significant difference between 2500-Hz BMAC and 1000-Hz BMAC (P = .046), and between 2500-Hz BMAC and 1000-Hz BMBPC (PHz BMAC and 1000-Hz BMBPC (P = .267). Conclusion For eliciting maximum knee extensor muscle torque, 1000-Hz BMBPC and 1000-Hz BMAC were similarly effective, and 2500-Hz BMAC was less effective. J Orthop Sports Phys Ther 2018;48(3):217-224. Epub 19 Dec 2017. doi:10.2519/jospt.2018.7601.

  20. Spin Transfer Torque in Graphene

    Science.gov (United States)

    Lin, Chia-Ching; Chen, Zhihong

    2014-03-01

    Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

  1. Computation of Electromagnetic Torque in a Double Rotor Switched Reluctance Motor Using Flux Tube Methods

    Directory of Open Access Journals (Sweden)

    Mohammad Hamiruce Marhaban

    2012-10-01

    Full Text Available With their highly robust nature and simple design, switched reluctance machines are finding their way into numerous modern day applications. However, they produce oscillatory torque that generates torque ripple and mechanical vibrations. A double rotor structure to maximize the flux linkage and thereby increase the torque generating capability is proposed. As the machine operates close to saturation, the torque computation depends heavily on the energy conversion as the rotor rolls over the stator for a fixed pole pitch. The flux linkage characteristics are highly non-linear, hence estimation of the magnetic and mechanical parameters is extremely cumbersome. Magnetic circuit analysis by interpretation of the number of flux tubes using integration techniques at different positions of the machine to develop the flux linkage characteristics of the double rotor structure is presented. Computation of the inductances during the movement of rotor from unaligned to aligned is crucial in determining the generated torque. Relevant equations of calculations for inductance and flux linkages in the aligned, partially aligned and unaligned positions are computed. The partially aligned computation is based on the average on two intermediate positions, namely the 1/4th aligned and 3/4th aligned conditions. The static torque characteristics based on the energy conversion principles are used to compute the torque value. Results from simulation and experiments used for performance evaluation of the proposed flux tube analysis for computation of the electro-magnetic torque are presented.

  2. Limited Angle Torque Motors Having High Torque Density, Used in Accurate Drive Systems

    Directory of Open Access Journals (Sweden)

    R. Obreja

    2011-01-01

    Full Text Available A torque motor is a special electric motor that is able to develop the highest possible torque in a certain volume. A torque motor usually has a pancake configuration, and is directly jointed to a drive system (without a gear box. A limited angle torque motor is a torque motor that has no rotary electromagnetic field — in certain papers it is referred to as a linear electromagnet. The main intention of the authors for this paper is to present a means for analyzing and designing a limited angle torque motor only through the finite element method. Users nowadays require very high-performance limited angle torque motors with high density torque. It is therefore necessary to develop the highest possible torque in a relatively small volume. A way to design such motors is by using numerical methods based on the finite element method.

  3. Heat-driven spin torques in antiferromagnets

    Science.gov (United States)

    Białek, Marcin; Bréchet, Sylvain; Ansermet, Jean-Philippe

    2018-04-01

    Heat-driven magnetization damping, which is a linear function of a temperature gradient, is predicted in antiferromagnets by considering the sublattice dynamics subjected to a heat-driven spin torque. This points to the possibility of achieving spin torque oscillator behavior. The model is based on the magnetic Seebeck effect acting on sublattices which are exchange coupled. The heat-driven spin torque is estimated and the feasibility of detecting this effect is discussed.

  4. Improvements in remote equipment torquing and fastening

    International Nuclear Information System (INIS)

    Garin, J.

    1978-01-01

    Remote torquing and fastening is a requirement of generic interest for application in an environment not readily accessible to man. The developments over the last 30 years in torque-controlled equipment above 200 nm (150 ft/lb) have not been emphasized. The development of specialized subassemblies to torque and fasten equipment in a remotely controlled environment is an integral part of the Advanced Fuel Recycle Program at Oak Ridge National Laboratory. Commercially available subassemblies have been adapted into a system that would provide remote torquing and fastening in the range of 200 to 750 nm (150 to 550 ft/lb). 9 figures

  5. The effects of ACL injury on quadriceps and hamstring torque, work and power.

    Science.gov (United States)

    Pincivero, Danny M; Heller, Brandan M; Hou, Su-I

    2002-09-01

    The aim of this study was to assess isokinetic torque, work and power between non-injured, ACL (anterior cruciate ligament)-deficient and ACL-reconstructed individuals. Ten healthy, non-injured individuals, seven unilateral ACL-deficient individuals and six unilateral ACL-reconstructed individuals were assessed for isokinetic quadriceps and hamstring strength at 1.05 and 3.14 rad.s-1. Peak torque, total work, average power and the ratio of peak torque to body mass were computed for both velocities. Peak torque was also corrected for body mass, using allometric modelling. The non-injured individuals showed significantly greater quadriceps peak torque to body mass ratios than the ACL-deficient and ACL-reconstructed individuals at both velocities, and greater hamstring peak torque to body mass ratios than the ACL-deficient group at 3.14 rad.s-1 (P quadriceps and hamstring peak torque, total work and average power than the non-injured individuals at 1.05 rad.s-1 (P quadriceps at both velocities (P hamstring peak torque and total work than the non-injured individuals at both velocities (P quadriceps muscle values were significantly higher in the non-involved than the involved limb. The hamstring peak torques corrected for body mass were significantly higher in the non-involved than the involved limb only at 1.05 rad.s-1. The main finding from the present study is that isokinetic measures in ratio-scaled or absolute units yield a different outcome and, hence, interpretation compared with the allometric approach.

  6. Game programmer's guide to Torque under the hood of the Torque game engine

    CERN Document Server

    Maurina , Edward F

    2006-01-01

    game programmer working with the Torque game engine must have ""The Game Programmer's Guide To Torque"": it teaches everything needed to design your own game, using experiences of game makers and industry veterans well versed in Torque technology. A Torque Game engine demo is included on an accompanying cd while step-by-step examples tell how to use it. Its focus on all the basics makes for an exceptional coverage for all levels of game programmer. -Bookwatch, August 2006

  7. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    Li, Hang

    2016-06-21

    Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read\\' and `write\\' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall

  8. 40 CFR 1065.310 - Torque calibration.

    Science.gov (United States)

    2010-07-01

    ... manufacturer's instructions for linearizing your torque sensor's output. We recommend that you calibrate the... combinations for each applicable torque-measuring range, spacing the weight quantities about equally over the... range, spacing the force quantities about equally over the range. Oscillate or rotate the dynamometer...

  9. Radiation Forces and Torques without Stress (Tensors)

    Science.gov (United States)

    Bohren, Craig F.

    2011-01-01

    To understand radiation forces and torques or to calculate them does not require invoking photon or electromagnetic field momentum transfer or stress tensors. According to continuum electromagnetic theory, forces and torques exerted by radiation are a consequence of electric and magnetic fields acting on charges and currents that the fields induce…

  10. A non-unity torque sharing function for torque ripple minimization of switched reluctance generators

    DEFF Research Database (Denmark)

    Park, Kiwoo; Liu, Xiao; Chen, Zhe

    2013-01-01

    This paper presents a new torque ripple minimization technique for a Switched Reluctance Generator (SRG). Although the SRG has many advantageous characteristics as a generator, it has not been widely employed in the industry. One of the most notorious disadvantages of the SRG is its high torque...... ripple. In this paper, a non-unity Torque Sharing Function (TSF) is proposed to minimize the torque ripple over a wide speed range of operation. Simulation results are presented to verify the effectiveness of the proposed torque ripple minimization technique....

  11. Next generation spin torque memories

    CERN Document Server

    Kaushik, Brajesh Kumar; Kulkarni, Anant Aravind; Prajapati, Sanjay

    2017-01-01

    This book offers detailed insights into spin transfer torque (STT) based devices, circuits and memories. Starting with the basic concepts and device physics, it then addresses advanced STT applications and discusses the outlook for this cutting-edge technology. It also describes the architectures, performance parameters, fabrication, and the prospects of STT based devices. Further, moving from the device to the system perspective it presents a non-volatile computing architecture composed of STT based magneto-resistive and all-spin logic devices and demonstrates that efficient STT based magneto-resistive and all-spin logic devices can turn the dream of instant on/off non-volatile computing into reality.

  12. Estimating Torque Imparted on Spacecraft Using Telemetry

    Science.gov (United States)

    Lee, Allan Y.; Wang, Eric K.; Macala, Glenn A.

    2013-01-01

    There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.

  13. Forearm Torque and Lifting Strength: Normative Data.

    Science.gov (United States)

    Axelsson, Peter; Fredrikson, Per; Nilsson, Anders; Andersson, Jonny K; Kärrholm, Johan

    2018-02-10

    To establish reference values for new methods designed to quantitatively measure forearm torque and lifting strength and to compare these values with grip strength. A total of 499 volunteers, 262 males and 237 females, aged 15 to 85 (mean, 44) years, were tested for lifting strength and forearm torque with the Kern and Baseline dynamometers. These individuals were also tested for grip strength with a Jamar dynamometer. Standardized procedures were used and information about sex, height, weight, hand dominance, and whether their work involved high or low manual strain was collected. Men had approximately 70% higher forearm torque and lifting strength compared with females. Male subjects aged 26 to 35 years and female subjects aged 36 to 45 years showed highest strength values. In patients with dominant right side, 61% to 78% had a higher or equal strength on this side in the different tests performed. In patients with dominant left side, the corresponding proportions varied between 41% and 65%. There was a high correlation between grip strength and forearm torque and lifting strength. Sex, body height, body weight, and age showed a significant correlation to the strength measurements. In a multiple regression model sex, age (entered as linear and squared) could explain 51% to 63% of the total variances of forearm torque strength and 30% to 36% of lifting strength. Reference values for lifting strength and forearm torque to be used in clinical practice were acquired. Grip strength has a high correlation to forearm torque and lifting strength. Sex, age, and height can be used to predict forearm torque and lifting strength. Prediction equations using these variables were generated. Normative data of forearm torque and lifting strength might improve the quality of assessment of wrist and forearm disorders as well as their treatments. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  14. Drag and Torque on Locked Screw Propeller

    Directory of Open Access Journals (Sweden)

    Tomasz Tabaczek

    2014-09-01

    Full Text Available Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades. The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.

  15. Immediate Effect of Grade IV Inferior Hip Joint Mobilization on Hip Abductor Torque: A Pilot Study.

    Science.gov (United States)

    Makofsky, Howard; Panicker, Siji; Abbruzzese, Jeanine; Aridas, Cynthia; Camp, Michael; Drakes, Jonelle; Franco, Caroline; Sileo, Ray

    2007-01-01

    Joint mobilization and manipulation stimulate mechanoreceptors, which may influence the joint and surrounding muscles. The purpose of this pilot study was to determine the effect of grade IV inferior hip joint mobilization on hip abductor torque. Thirty healthy subjects were randomly assigned to a control group (grade I inferior hip joint mobilization) or an experimental group (grade IV inferior hip joint mobilization). Subjects performed a pre- and post-intervention test of five isometric repetitions on the Cybex Normö dynamometer; the average torque was determined for both pre- and post-intervention measurements. These data were analyzed using the independent samples t-test with the significance level set at Phip abductor torque in the experimental group (P=0.03). The experimental group demonstrated a 17.35% increase in average torque whereas the control group demonstrated a 3.68% decrease in average torque. These findings are consistent with other studies demonstrating that the use of grade IV non-thrust mobilization improves strength immediately post-intervention in healthy individuals. The results of this pilot study provide physical therapists with further support for the utilization of manual therapy in conjunction with therapeutic exercise to enhance muscle strength.

  16. A flexoelectricity effect-based sensor for direct torque measurement

    International Nuclear Information System (INIS)

    Zhang, Shuwen; Xu, Minglong; Liu, Kaiyuan; Shen, Shengping

    2015-01-01

    In this study, a direct torque sensor based on the flexoelectricity generated by un-polarized polyvinylidene fluoride (PVDF) via electromechanical coupling is developed as a novel torque measurement mechanism that does not require external electric power excitation. The sensing method is developed based on the shear strain gradient and the shear flexoelectric response of PVDF. A theoretical analysis is primarily presented for the design of the sensing structure. Then the structure of the PVDF sensing module is discussed and designed. The radius ratio of the sensing module is defined and then discussed according to the load, the strain gradient, the electrode area and the general electric charge output. The finite element method is used to analyze the mechanical properties of the designed PVDF sensing module. Then the theoretical sensitivity of the sensor is predicated as 0.9441 pC Nm −1 . The experiment system setup is developed, and the sensing properties of the measurement mechanism are tested at frequencies of 0.5 Hz, 1 Hz, 1.5 Hz and 2 Hz using identical modules. The measurement range of the designed sensor is 0–1.68 Nm and the average sensitivity is measured as 0.8950 pC Nm −1 . The experimental results agree well with the theoretically predicted results. These results prove that the torque sensing method based on un-polarized PVDF is suitable for measurement of dynamic torque loads with a flexoelectricity-based mechanism. When using this method, external electric power excitation of the sensing module is no longer required. (paper)

  17. A flexoelectricity effect-based sensor for direct torque measurement

    Science.gov (United States)

    Zhang, Shuwen; Xu, Minglong; Liu, Kaiyuan; Shen, Shengping

    2015-12-01

    In this study, a direct torque sensor based on the flexoelectricity generated by un-polarized polyvinylidene fluoride (PVDF) via electromechanical coupling is developed as a novel torque measurement mechanism that does not require external electric power excitation. The sensing method is developed based on the shear strain gradient and the shear flexoelectric response of PVDF. A theoretical analysis is primarily presented for the design of the sensing structure. Then the structure of the PVDF sensing module is discussed and designed. The radius ratio of the sensing module is defined and then discussed according to the load, the strain gradient, the electrode area and the general electric charge output. The finite element method is used to analyze the mechanical properties of the designed PVDF sensing module. Then the theoretical sensitivity of the sensor is predicated as 0.9441 pC Nm-1. The experiment system setup is developed, and the sensing properties of the measurement mechanism are tested at frequencies of 0.5 Hz, 1 Hz, 1.5 Hz and 2 Hz using identical modules. The measurement range of the designed sensor is 0-1.68 Nm and the average sensitivity is measured as 0.8950 pC Nm-1. The experimental results agree well with the theoretically predicted results. These results prove that the torque sensing method based on un-polarized PVDF is suitable for measurement of dynamic torque loads with a flexoelectricity-based mechanism. When using this method, external electric power excitation of the sensing module is no longer required.

  18. High Torque, Direct Drive Electric Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Bear Engineering proposes to advance the development of an innovative high torque, low speed, direct drive motor in order to meet NASA's requirements for such...

  19. Sensorless vector and direct torque control

    CERN Document Server

    Vas, Peter

    1998-01-01

    This is the first comprehensive book on sensorless high performance a.c. drives. It is essential reading for anyone interested in acquiring a solid background on sensorless torque-controlled drives. It presents a detailed and unified treatment of sensorless vector-controlled and direct-torque controlled drive systems. It also discusses the applications of artificial intelligence to drives. Where possible, space vector theory is used and emphasis is laid on detailed mathematical and physical analysis. Sensorless drive schemes for different types of permanent magnet synchronous motors, synchronous reluctance motors, and induction motors are also presented. These include more than twenty vector drives e.g. five types of MRAS-based vector drives, and eleven types of direct-torque-controlled (DTC) drives, e.g. the ABB DTC drive. However, torque-controlled switched reluctance motor drives are also discussed due to their emerging importance. The book also covers various drive applications using artificial intellige...

  20. Improved computed torque control for industrial robots

    Science.gov (United States)

    Uebel, Mark; Minis, Ioannis; Cleary, Kevin

    1992-01-01

    The authors examine the computed torque control problem for a robot arm with flexible, geared, joint drive systems which are typical in many industrial robots. The standard computed torque algorithm is not directly applicable to this class of manipulators due to the dynamics introduced by the joint drive systems. The proposed approach overcomes this problem by combining a novel computed torque algorithm with simple torque controllers at each joint of the robot. The control scheme is applied to a seven degree-of-freedom industrial manipulator, and the system performance in standard tasks is evaluated using both dynamic simulation and actual experiments. The results show that the proposed controller leads to improved tracking performance over a conventional PD (proportional plus derivative) controller.

  1. High-torque magnetorheological fluid clutch

    Science.gov (United States)

    Kavlicoglu, Barkan M.; Gordaninejad, Faramarz; Evrensel, Cahit A.; Cobanoglu, Nigar; Liu, Yanming; Fuchs, Alan; Korol, George

    2002-06-01

    This study focuses on the design and characterization of a radial double-plate magneto-rheological fluid (MRF) clutch. The clutch's torque output can be controlled by adjusting the applied magnetic field. Electromagnetic finite element analysis (FEA) is performed to design and optimize the clutch. The shear stress distribution in MRF between the plates is theoretically predicted using the magnetic flux density distribution evaluated from the FEA. The output torque of the clutch is derived by using the Bingham plastic constitutive model. The output torque values are recorded for different input velocities and applied magnetic fields, and they are compared with the theoretical results. It was demonstrated that the clutch is capable of producing high controllable torques.

  2. 14 CFR 23.361 - Engine torque.

    Science.gov (United States)

    2010-01-01

    ... takeoff power and propeller speed, multiplied by a factor accounting for propeller control system... compressor jamming). (2) A limit engine torque load imposed by the maximum acceleration of the engine. (c...

  3. 14 CFR 25.361 - Engine torque.

    Science.gov (United States)

    2010-01-01

    ... by a factor accounting for propeller control system malfunction, including quick feathering, acting... malfunction or structural failure (such as compressor jamming). (2) A limit engine torque load imposed by the...

  4. Magnetic anisotropy of nickel nanorods and the mechanical torque in an elastic environment

    Science.gov (United States)

    Schopphoven, C.; Tschöpe, A.

    2018-03-01

    Nickel nanorods with average length L=340~nm and diameter D=20~nm were prepared by the anodic aluminum oxide (AAO)-template method, processed to a colloidal dispersion and embedded in a gelatine hydrogel matrix at low volume fraction φ ≤slant 10-4 . The large aspect ratio of these single-domain particles gives rise to a high magnetic shape anisotropy in combination with a significant anisotropic optical polarizability. The magnetic anisotropy enables exertion of a torque on nanorods without contact by applying a homogeneous magnetic field. In response, the nanorods rotate by an angle which is determined by the balance between the magnetic torque and the mechanical counter torque, caused by the elastic deformation of the surrounding matrix. This rotation was experimentally detected using optical transmission of linearly polarized light. We used the combination of magnetization and torque-driven rotation measurements to evaluate an adapted Stoner-Wohlfarth model of the orientation- and field-dependent magnetic torque on Ni nanorods in an elastic environment as base for optimization of torque-driven magnetic actuators.

  5. Averaging in cosmological models

    OpenAIRE

    Coley, Alan

    2010-01-01

    The averaging problem in cosmology is of considerable importance for the correct interpretation of cosmological data. We review cosmological observations and discuss some of the issues regarding averaging. We present a precise definition of a cosmological model and a rigorous mathematical definition of averaging, based entirely in terms of scalar invariants.

  6. Knudsen torque on heated micro beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qi; Liang, Tengfei; Ye, Wenjing [Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon (Hong Kong)

    2014-12-09

    Thermally induced mechanical loading has been shown to have significant effects on micro/nano objects immersed in a gas with a non-uniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Using the asymptotic analysis in the near continuum regime, the Knudsen torque acting on an asymmetrically located uniformly heated microbeam in a cold enclosure is investigated. The existence of a non-zero net torque is demonstrated. In addition, it has been found that by manipulating the system configuration, the rotational direction of the torque can be changed. Two types of rotational motion of the microbeam have been identified: the pendulum motion of a rectangular beam, and the unidirectional rotation of a cylindrical beam. A rotational frequency of 4 rpm can be achieved for the cylindrical beam with a diameter of 3μm at Kn = 0.005. Illustrated by the simulations using the direct simulation of Monte Carlo, the Knudsen torque can be much increased in the transition regime, demonstrating the potential of Knudsen torque serving as a rotation engine for micro/nano objects.

  7. Extraneous torque and compensation control on the electric load simulator

    Science.gov (United States)

    Jiao, Zongxia; Li, Chenggong; Ren, Zhiting

    2003-09-01

    In this paper a novel motor-drive load simulator based on compensation control strategy is proposed and designed. Through analyzing the torque control system consisting of DC torque motor, PWM module and torque sensor, it is shown that performance of the motor-drive load simulator is possible to be as good as that of the electro-hydraulic load simulator in the range of small torque. In the course of loading, the rotation of the actuator would cause a strong disturbance torque through the motor back-EMF, which produces extraneous torque similar as in electro-hydraulic load simulator. This paper analyzes the cause of extraneous torque inside the torque motor in detail and presents an appropriate compensation control with which the extraneous torque can be compensated and the good performance of the torque control system can be obtained. The results of simulation indicate that the compensation is very effective and the track performance is according with the request.

  8. Study on torque algorithm of switched reluctance motor

    Directory of Open Access Journals (Sweden)

    Xiaoguang LI

    2016-12-01

    Full Text Available To solve the torque ripple problem of switched reluctance motor under the traditional control method, a direct torque control method for switched reluctance motor is proposed. Direct torque algorithm controls flux magnitude and direction by querying appropriate voltage vector in switch list. Taking torque as direct control variable can reduce the torque ripple of the motor, which broadens the application fields of switched reluctance motor. Starting with the theory of direct torque algorithm, based on MATLAB/Simulink platform, direct torque control and chopped current control system simulation model are designed. Under the condition that switched reluctance motor model and its load are consistent, it is compared with chopped current algorithm. At last, the feasibility of direct torque algorithm is verified through the platform of hardware experiments. It demonstrates that using direct torque algorithm can make the torque ripple be controlled effectively, which provides a wider application field for the switched reluctance motor.

  9. Potentiation increases peak twitch torque by enhancing rates of torque development and relaxation.

    Science.gov (United States)

    Froyd, Christian; Beltrami, Fernando Gabe; Jensen, Jørgen; Noakes, Timothy David

    2013-01-01

    The aim of this study was to measure the extent to which potentiation changes in response to an isometric maximal voluntary contraction. Eleven physically active subjects participated in two separate studies. Single stimulus of electrical stimulation of the femoral nerve was used to measure torque at rest in unpotentiated quadriceps muscles (study 1 and 2), and potentiated quadriceps muscles torque in a 10 min period after a 5 s isometric maximal voluntary contraction of the quadriceps muscles (study 1). Additionally, potentiated quadriceps muscles torque was measured every min after a further 10 maximal voluntary contractions repeated every min (study 2). Electrical stimulation repeated several times without previous maximal voluntary contraction showed similar peak twitch torque. Peak twitch torque 4 s after a 5 s maximal voluntary contraction increased by 45±13% (study 1) and by 56±10% (study 2), the rate of torque development by 53±13% and 82±29%, and the rate of relaxation by 50±17% and 59±22%, respectively, but potentiation was lost already two min after a 5 s maximal voluntary contraction. There was a tendency for peak twitch torque to increase for the first five repeated maximal voluntary contractions, suggesting increased potentiation with additional maximal voluntary contractions. Correlations for peak twitch torque vs the rate of torque development and for the rate of relaxation were r(2)= 0.94 and r(2)=0.97. The correlation between peak twitch torque, the rate of torque development and the rate of relaxation suggests that potentiation is due to instantaneous changes in skeletal muscle contractility and relaxation.

  10. Standard practice for calibration of torque-measuring instruments for verifying the torque indication of torque testing machines

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This practice is to specify procedure for the calibration of elastic torque-measuring instruments. Note 1—Verification by deadweight and a lever arm is an acceptable method of verifying the torque indication of a torque testing machine. Tolerances for weights used are tabulated in Practice WK6364; methods for calibration of the weights are given in NIST Technical Note 577, Methods of Calibrating Weights for Piston Gages. 1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.3 This practice is intended for the calibration of static or quasi-static torque measuring instruments. The practice is not applicable for high speed torque calibrations or measurements. 1.4 This standard does not purport to address all of the safety concerns, if any,...

  11. A method to accurately estimate the muscular torques of human wearing exoskeletons by torque sensors.

    Science.gov (United States)

    Hwang, Beomsoo; Jeon, Doyoung

    2015-04-09

    In exoskeletal robots, the quantification of the user's muscular effort is important to recognize the user's motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users' muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user's limb accurately from the measured torque. The user's limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user's muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions.

  12. A Method to Accurately Estimate the Muscular Torques of Human Wearing Exoskeletons by Torque Sensors

    Directory of Open Access Journals (Sweden)

    Beomsoo Hwang

    2015-04-01

    Full Text Available In exoskeletal robots, the quantification of the user’s muscular effort is important to recognize the user’s motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users’ muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user’s limb accurately from the measured torque. The user’s limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user’s muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions.

  13. Decoupled Speed and Torque Control of IPMSM Drives Using a Novel Load Torque Estimator

    Directory of Open Access Journals (Sweden)

    ZAKY, M.

    2017-08-01

    Full Text Available This paper proposes decoupled speed and torque control of interior permanent magnet synchronous motor (IPMSM drives using a novel load torque estimator (LTE. The proposed LTE is applied for computing a load torque and yielding a feed-forward value in the speed controller to separate the torque control from the speed control. Indirect flux weakening using direct current component is obtained for high speed operation of the IPMSM drive, and its value for maximum torque per ampere (MTPA control in constant torque region is also used. LTE uses values of direct and quadrature currents to improve the behavior of the speed controller under the reference tracking and torque disturbances. The complete IPMSM drive by Matlab/Simulink is built. The effectiveness of the proposed control scheme using an experimental setup of the complete drive system implemented on a DSP-DS1102 control board is confirmed. Extensive results over a wide speed range are verified. The efficacy of the proposed method is confirmed in comparison to a conventional PI controller under both the reference speed tracking and load torque disturbance.

  14. A Method to Accurately Estimate the Muscular Torques of Human Wearing Exoskeletons by Torque Sensors

    Science.gov (United States)

    Hwang, Beomsoo; Jeon, Doyoung

    2015-01-01

    In exoskeletal robots, the quantification of the user’s muscular effort is important to recognize the user’s motion intentions and evaluate motor abilities. In this paper, we attempt to estimate users’ muscular efforts accurately using joint torque sensor which contains the measurements of dynamic effect of human body such as the inertial, Coriolis, and gravitational torques as well as torque by active muscular effort. It is important to extract the dynamic effects of the user’s limb accurately from the measured torque. The user’s limb dynamics are formulated and a convenient method of identifying user-specific parameters is suggested for estimating the user’s muscular torque in robotic exoskeletons. Experiments were carried out on a wheelchair-integrated lower limb exoskeleton, EXOwheel, which was equipped with torque sensors in the hip and knee joints. The proposed methods were evaluated by 10 healthy participants during body weight-supported gait training. The experimental results show that the torque sensors are to estimate the muscular torque accurately in cases of relaxed and activated muscle conditions. PMID:25860074

  15. Torque shudder protection device and method

    Science.gov (United States)

    King, R.D.; Doncker, R.W.A.A. De.; Szczesny, P.M.

    1997-03-11

    A torque shudder protection device for an induction machine includes a flux command generator for supplying a steady state flux command and a torque shudder detector for supplying a status including a negative status to indicate a lack of torque shudder and a positive status to indicate a presence of torque shudder. A flux adapter uses the steady state flux command and the status to supply a present flux command identical to the steady state flux command for a negative status and different from the steady state flux command for a positive status. A limiter can receive the present flux command, prevent the present flux command from exceeding a predetermined maximum flux command magnitude, and supply the present flux command to a field oriented controller. After determining a critical electrical excitation frequency at which a torque shudder occurs for the induction machine, a flux adjuster can monitor the electrical excitation frequency of the induction machine and adjust a flux command to prevent the monitored electrical excitation frequency from reaching the critical electrical excitation frequency. 5 figs.

  16. Electrostatic sensor modeling for torque measurements

    Science.gov (United States)

    Mika, Michał; Dannert, Mirjam; Mett, Felix; Weber, Harry; Mathis, Wolfgang; Nackenhorst, Udo

    2017-09-01

    Torque load measurements play an important part in various engineering applications, as for automotive industry, in which the drive torque of a motor has to be determined. A widely used measuring method are strain gauges. A thin flexible foil, which supports a metallic pattern, is glued to the surface of the object the torque is being applied to. In case of a deformation due to the torque load, the change in the electrical resistance is measured. With the combination of constitutive equations the applied torque load is determined by the change of electrical resistance. The creep of the glue and the foil material, together with the temperature and humidity dependence, may become an obstacle for some applications Kapralov and Fesenko (1984). Thus, there have been optical and magnetical, as well as capacitive sensors introduced). This paper discusses the general idea behind an electrostatic capacitive sensor based on a simple draft of an exemplary measurement setup. For better understanding an own electrostatical, geometrical and mechanical model of this setup has been developed.

  17. Electrostatic sensor modeling for torque measurements

    Directory of Open Access Journals (Sweden)

    M. Mika

    2017-09-01

    Full Text Available Torque load measurements play an important part in various engineering applications, as for automotive industry, in which the drive torque of a motor has to be determined. A widely used measuring method are strain gauges. A thin flexible foil, which supports a metallic pattern, is glued to the surface of the object the torque is being applied to. In case of a deformation due to the torque load, the change in the electrical resistance is measured. With the combination of constitutive equations the applied torque load is determined by the change of electrical resistance. The creep of the glue and the foil material, together with the temperature and humidity dependence, may become an obstacle for some applications Kapralov and Fesenko(1984. Thus, there have been optical and magnetical, as well as capacitive sensors introduced . This paper discusses the general idea behind an electrostatic capacitive sensor based on a simple draft of an exemplary measurement setup. For better understanding an own electrostatical, geometrical and mechanical model of this setup has been developed.

  18. the impact of machine geometries on the average torque of dual ...

    African Journals Online (AJOL)

    HOD

    in Figure 1, has the same number of independent parts with that proposed in [7], however, with huge structural differences, especially in the arrangement of. PMs and total number of rotor(s) and stator(s). It should be noted that, the analysed machine in this study is devoid of permanent magnets in its outer stator. Moreover ...

  19. Macroscopic description of spin transfer torque

    International Nuclear Information System (INIS)

    Barnas, J.; Fert, A.; Gmitra, M.; Weymann, I.; Dugaev, V.K.

    2006-01-01

    A macroscopic description of the current-induced torque due to spin transfer has been developed for layered systems consisting of ferromagnetic films, separated by nonmagnetic layers. The description is based on the classical spin diffusion equations for the distribution functions used in the theory of current-perpendicular-to-plane giant magnetoresistance (CPP-GMR), and the relevant boundary conditions for the longitudinal and transverse components of the spin current and spin accumulation. The torque is expressed as a function of the usual parameters derived from CPP-GMR experiments and two additional parameters involved in the transverse boundary conditions. The model describes qualitatively the normal and inverse switching phenomena studied in recent experiments. We also discuss a structure for which the spin torque disappears at a noncollinear magnetic configuration

  20. Helicopter Anti-Torque System Using Strakes

    Science.gov (United States)

    Kelley, H. L.; Wilson, J. C.; Phelps, A. E. (Inventor)

    1984-01-01

    A helicopter is disclosed with a system for controlling main-rotor torque which reduces the power and size requirements of conventional anti-torque means. The torque countering forces are generated by disrupting the main rotor downwash flowing around the fuselage. The downwash flow is separated from the fuselage surface by a strake positioned at a specified location on the fuselage. This location is determined by the particular helicopter wash pattern and fuselage configuration, generally being located between 20 deg before top dead center (TDC) and 80 deg from TDC on the fuselage side to which the main rotor blade approaches during rotation. The strake extends along the fuselage from the cabin section to the aft end and can be continuous or separated for aerodynamic surfaces such as a horizontal stabilizer.

  1. RFID Torque Sensing Tag System for Fasteners

    Science.gov (United States)

    Fink, Patrick W. (Inventor); Lin, Gregory Y. (Inventor); Ngo, Phong H. (Inventor); Kennedy, Timothy F. (Inventor)

    2016-01-01

    The present invention provides an RFID-based torque sensor that can be used to quickly monitor off the shelf fasteners including fasteners that are used in expensive satellites or other uses where fastener failure can be very costly. In one embodiment, an antenna, RFID ring and spring comprise a sensor tag that can be interrogated with an interrogation signal produced by an interrogator device. When sufficient torque is applied to the fastener, an RFID circuit is connected, and produces a radio frequency (RF) signal that can be read by the interrogator. In one embodiment, the RFID circuit does not transmit when the spring member is not compressed, thereby indicating insufficient tensioning of the fastener. The present invention offers the ability to remotely, quickly, and inexpensively verify that any number of fasteners are torqued properly upon initial installation. Where applicable, the present invention allows low cost monitoring over the life of the fastener.

  2. Self-Induced Torque in Hyperbolic Metamaterials

    Science.gov (United States)

    Ginzburg, Pavel; Krasavin, Alexey V.; Poddubny, Alexander N.; Belov, Pavel A.; Kivshar, Yuri S.; Zayats, Anatoly V.

    2013-07-01

    Optical forces constitute a fundamental phenomenon important in various fields of science, from astronomy to biology. Generally, intense external radiation sources are required to achieve measurable effects suitable for applications. Here we demonstrate that quantum emitters placed in a homogeneous anisotropic medium induce self-torques, aligning themselves in the well-defined direction determined by an anisotropy, in order to maximize their radiation efficiency. We develop a universal quantum-mechanical theory of self-induced torques acting on an emitter placed in a material environment. The theoretical framework is based on the radiation reaction approach utilizing the rigorous Langevin local quantization of electromagnetic excitations. We show more than 2 orders of magnitude enhancement of the self-torque by an anisotropic metamaterial with hyperbolic dispersion, having negative ratio of permittivity tensor components, in comparison with conventional anisotropic crystals with the highest naturally available anisotropy.

  3. AX-5 space suit bearing torque investigation

    Science.gov (United States)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  4. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  5. Development of a magnetostrictive Torque sensor. Jiwaishiki torque sensor no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Tanizaki, K.; Aoki, H.; Maruyama, J.; Shimada, M. (Nissan Motor Co. Ltd., Tokyo (Japan))

    1990-06-25

    In the present report, new torque sensor, utilizing the magnetostrictive effect, was explained in structure of sensor, material problem of the shaft, playing a functionally important role therein, and examples, verifying the characteristics. The magnetic substance is constituted as a set substance of small regions, called magnetic sections, directionally constant in spontaneous magnetization. If stress acts on the magnetic substance, there occur dislocation of magnetic wall, which is border between those sections, and rotation of magnetization, which occurrence causes change in magnetization of all the magnetic substance, ie., magnetostrictive effect. The torque sensor constitutes plural concave/convex forms, directionally oblique to the main torsional stress, on the shaft surface, composed as magnetic substance, and which surface is installed confrontedly with a pair of coils. Result of using a torque sensor for the engine torque measurement could grasp, in each cylinder, both torque generation by combustion and torque decrease by flameout, good in respondency. Example for the transmission to be internally equipped with a sensor could also grasp a large and very quick change in torque with a high respondency. 8 refs., 14 figs.

  6. The role of interaction torque and muscle torque in the control of downward squatting

    OpenAIRE

    Fujisawa, Hiroyuki; Suzuki, Hiroto; Murakami, Kenichi; Kawakami, Shingo; Suzuki, Makoto

    2016-01-01

    [Purpose] The purposes of this study were first to analyze the multijoint dynamics of downward squatting, and to examine the contribution of interaction torque and muscle torque to net torque, and second, to examine mechanisms of movement control. [Subjects] The subjects were 31 healthy men with a mean age of 21.0 ? 1.2?years (range, 19?24?years). [Methods] Squatting tasks with the trunk in two positions, an erect and anterior tilt position, were performed by the subjects. Net, interaction, m...

  7. New Simple Torque-Sensorless Torque Control for Quasi-Perfect Compensation of 6th Harmonic Torque Ripple Due to Nonsinusoidal Distribution of Back EMF of PMSM

    Science.gov (United States)

    Shinnaka, Shinji; Kishida, Hideo

    This paper proposes a new torque-sensorless torque control method for permanent-magnet synchronous motors (PMSMs). The proposed method can almost perfectly compensate the 6th harmonic torque ripple that is caused by the nonsinusoidal distributions of the back EMF and rotor magnetic flux of PMSMs. The torque control system is, in principle, constructed on the basis of the vector control, but has two new dedicated speed-varying devices—a harmonic torque observer and current controller. The speed-varying harmonic torque observer can estimate the harmonic component over a wide speed range, even in the case where the produced torque is constant, and generate a suitable compensating signal. The speed-varying current controller shows stable control performance over a wide speed range, it can fully track the compensated current command containing the dc and 6th harmonic components. The effectiveness of the proposed method is examined and verified through extensive numerical experiments.

  8. Torque limit of PM motors for field-weakening region operation

    Science.gov (United States)

    Royak, Semyon [Beachwood, OH; Harbaugh, Mark M [Richfield, OH

    2012-02-14

    The invention includes a motor controller and technique for controlling a permanent magnet motor. In accordance with one aspect of the present technique, a permanent magnet motor is controlled by receiving a torque command, determining a physical torque limit based on a stator frequency, determining a theoretical torque limit based on a maximum available voltage and motor inductance ratio, and limiting the torque command to the smaller of the physical torque limit and the theoretical torque limit. Receiving the torque command may include normalizing the torque command to obtain a normalized torque command, determining the physical torque limit may include determining a normalized physical torque limit, determining a theoretical torque limit may include determining a normalized theoretical torque limit, and limiting the torque command may include limiting the normalized torque command to the smaller of the normalized physical torque limit and the normalized theoretical torque limit.

  9. Effects of Velocity on Electromyographic, Mechanomyographic, and Torque Responses to Repeated Eccentric Muscle Actions.

    Science.gov (United States)

    Hill, Ethan C; Housh, Terry J; Camic, Clayton L; Smith, Cory M; Cochrane, Kristen C; Jenkins, Nathaniel D M; Cramer, Joel T; Schmidt, Richard J; Johnson, Glen O

    2016-06-01

    The purposes of this study were to examine the effects of the velocity of repeated eccentric muscle actions on the torque and neuromuscular responses during maximal isometric and eccentric muscle actions. Twelve resistance-trained men performed 30 repeated, maximal, eccentric, isokinetic muscle actions at randomly ordered velocities of 60, 120, or 180°·s on separate days. Maximal voluntary isometric contractions (MVICs) were performed before (pretest) and after (posttest) the repeated eccentric muscle actions on each day. Eccentric isokinetic peak torque (EIPT) values were the averages of the first 3 and last 3 repetitions of the 30 repeated eccentric muscle actions. During the EIPT and MVIC muscle actions, electromyographic (EMG) and mechanomyographic (MMG) amplitude (EMG AMP and MMG AMP) and mean power frequency (EMG MPF and MMG MPF) values were assessed. These results indicated that the repeated eccentric muscle actions had no effects on EIPT, or the EMG AMP, EMG MPF, or MMG MPF values assessed during the EIPT muscle actions, but decreased MMG AMP. The repeated eccentric muscle actions, however, decreased MVIC torque, and also the EMG AMP and MMG MPF values assessed during the MVIC muscle actions, but increased MMG AMP. The results indicated that the velocity of the repeated eccentric muscle actions affected the MVIC torque responses, but not EIPT or any of the neuromuscular parameters. Furthermore, there are differences in the torque and neuromuscular responses for isometric vs. eccentric muscle actions after repeated eccentric muscle actions.

  10. Planetary Torque in 3D Isentropic Disks

    Energy Technology Data Exchange (ETDEWEB)

    Fung, Jeffrey [Department of Astronomy, University of California at Berkeley, Campbell Hall, Berkeley, CA 94720-3411 (United States); Masset, Frédéric; Velasco, David [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, 62210 Cuernavaca, Mor. (Mexico); Lega, Elena, E-mail: jeffrey.fung@berkeley.edu [Université de la Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange UMR 7293, Nice (France)

    2017-03-01

    Planetary migration is inherently a three-dimensional (3D) problem, because Earth-size planetary cores are deeply embedded in protoplanetary disks. Simulations of these 3D disks remain challenging due to the steep resolution requirements. Using two different hydrodynamics codes, FARGO3D and PEnGUIn, we simulate disk–planet interaction for a one to five Earth-mass planet embedded in an isentropic disk. We measure the torque on the planet and ensure that the measurements are converged both in resolution and between the two codes. We find that the torque is independent of the smoothing length of the planet’s potential ( r {sub s}), and that it has a weak dependence on the adiabatic index of the gaseous disk ( γ ). The torque values correspond to an inward migration rate qualitatively similar to previous linear calculations. We perform additional simulations with explicit radiative transfer using FARGOCA, and again find agreement between 3D simulations and existing torque formulae. We also present the flow pattern around the planets that show active flow is present within the planet’s Hill sphere, and meridional vortices are shed downstream. The vertical flow speed near the planet is faster for a smaller r {sub s} or γ , up to supersonic speeds for the smallest r {sub s} and γ in our study.

  11. Are torque values of preadjusted brackets precise?

    Directory of Open Access Journals (Sweden)

    Alessandra Motta Streva

    Full Text Available OBJECTIVE: The aim of the present study was to verify the torque precision of metallic brackets with MBT prescription using the canine brackets as the representative sample of six commercial brands. MATERIAL AND METHODS: Twenty maxillary and 20 mandibular canine brackets of one of the following commercial brands were selected: 3M Unitek, Abzil, American Orthodontics, TP Orthodontics, Morelli and Ortho Organizers. The torque angle, established by reference points and lines, was measured by an operator using an optical microscope coupled to a computer. The values were compared to those established by the MBT prescription. RESULTS: The results showed that for the maxillary canine brackets, only the Morelli torque (-3.33º presented statistically significant difference from the proposed values (-7º. For the mandibular canines, American Orthodontics (-6.34º and Ortho Organizers (-6.25º presented statistically significant differences from the standards (-6º. Comparing the brands, Morelli presented statistically significant differences in comparison with all the other brands for maxillary canine brackets. For the mandibular canine brackets, there was no statistically significant difference between the brands. CONCLUSIONS: There are significant variations in torque values of some of the brackets assessed, which would clinically compromise the buccolingual positioning of the tooth at the end of orthodontic treatment.

  12. Planetary Torque in 3D Isentropic Disks

    International Nuclear Information System (INIS)

    Fung, Jeffrey; Masset, Frédéric; Velasco, David; Lega, Elena

    2017-01-01

    Planetary migration is inherently a three-dimensional (3D) problem, because Earth-size planetary cores are deeply embedded in protoplanetary disks. Simulations of these 3D disks remain challenging due to the steep resolution requirements. Using two different hydrodynamics codes, FARGO3D and PEnGUIn, we simulate disk–planet interaction for a one to five Earth-mass planet embedded in an isentropic disk. We measure the torque on the planet and ensure that the measurements are converged both in resolution and between the two codes. We find that the torque is independent of the smoothing length of the planet’s potential ( r s ), and that it has a weak dependence on the adiabatic index of the gaseous disk ( γ ). The torque values correspond to an inward migration rate qualitatively similar to previous linear calculations. We perform additional simulations with explicit radiative transfer using FARGOCA, and again find agreement between 3D simulations and existing torque formulae. We also present the flow pattern around the planets that show active flow is present within the planet’s Hill sphere, and meridional vortices are shed downstream. The vertical flow speed near the planet is faster for a smaller r s or γ , up to supersonic speeds for the smallest r s and γ in our study.

  13. Stabilization of Rigid Body Dynamics by Internal and External Torques

    National Research Council Canada - National Science Library

    Bloch, A. M; Krishnaprasad, P. S; Marsden, J. E; Sanchez de Alvarez, G

    1990-01-01

    ...] with quadratic feedback torques for internal rotors. We show that with such torques, the equations for the rigid body with momentum wheels are Hamiltonian with respect to a Lie-Poisson bracket structure. Further...

  14. Comparison of Stretch Reflex Torques in Ankle Dorsiflexors and Plantarflexors

    National Research Council Canada - National Science Library

    Tung, J

    2001-01-01

    ...) ankle muscles, Pulse, step, and a combination of random perturbation and step inputs were used to identify the reflex and intrinsic contributions to the measured torque, TA reflex torques were very...

  15. Muscle shear elastic modulus is linearly related to muscle torque over the entire range of isometric contraction intensity.

    Science.gov (United States)

    Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine

    2015-08-01

    Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Average-energy games

    Directory of Open Access Journals (Sweden)

    Patricia Bouyer

    2015-09-01

    Full Text Available Two-player quantitative zero-sum games provide a natural framework to synthesize controllers with performance guarantees for reactive systems within an uncontrollable environment. Classical settings include mean-payoff games, where the objective is to optimize the long-run average gain per action, and energy games, where the system has to avoid running out of energy. We study average-energy games, where the goal is to optimize the long-run average of the accumulated energy. We show that this objective arises naturally in several applications, and that it yields interesting connections with previous concepts in the literature. We prove that deciding the winner in such games is in NP inter coNP and at least as hard as solving mean-payoff games, and we establish that memoryless strategies suffice to win. We also consider the case where the system has to minimize the average-energy while maintaining the accumulated energy within predefined bounds at all times: this corresponds to operating with a finite-capacity storage for energy. We give results for one-player and two-player games, and establish complexity bounds and memory requirements.

  17. Increasing Elbow Torque Output of Stroke Patients by EMG-Controlled External Torque

    National Research Council Canada - National Science Library

    Lin, C

    2001-01-01

    .... The control signal to the manipulator is the difference between the weighted biceps and triceps EMG, so that the system moves with the forearm and provides assisting torque proportional to the voluntary effort...

  18. Direct Torque Control of Asynchronous Motor With Fuzzy Logic Swithching

    OpenAIRE

    KORKMAZ, Fatih; KORKMAZ, Yılmaz

    2011-01-01

    control method in asynchronous motors, are known as high speed and torque ripples. In this study, direct torque control with fuzzy logic based switching method have been studied in order to reduce the speed and torque ripples which occurs during the direct torque control of asynchronous motors. Hysteresis controllers and vector selector that used in conventional control were removed, and fuzzy logic based switching method was used instead of them. Conventional and fuzzy control methods were s...

  19. Improved direct torque control of induction motor with dither injection

    Indian Academy of Sciences (India)

    dither signal is injected of minute amplitude (5% of rated torque and 5% of reference flux as hysteresis band in torque control and flux control loops respectively) in the error block. The optimal value of dither frequency and magnitude is found out under free running condition. This technique gives minimum torque ripple, low ...

  20. Calculation of Cogging Torque in Hybrid Stepping Motors | Agber ...

    African Journals Online (AJOL)

    When the windings of a hybrid stepping motor are unexcited the permanent magnet's flux produces cogging torque. This torque has both desirable and undesirable features depending on the application that the motor is put into. This paper formulates an analytical method for predicting cogging torque using measured ...

  1. Improved direct torque control of induction motor with dither injection

    Indian Academy of Sciences (India)

    Abstract. In this paper, a three-level inverter-fed induction motor drive operating under Direct Torque Control (DTC) is presented. A triangular wave is used as dither signal of minute amplitude (for torque hysteresis band and flux hysteresis band respectively) in the error block. This method minimizes flux and torque ripple in ...

  2. Averaging operations on matrices

    Indian Academy of Sciences (India)

    2014-07-03

    Jul 3, 2014 ... Arithmetic mean of objects in a space need not lie in the space. [Frechet; 1948] Finding mean of right-angled triangles. S = {(x,y,z) ∈ R+3 : x2 + y2 = z2}. = {. [ z x − ιy x + ιy z. ] : x,y,z > 0,z2 = x2 + y2}. Surface of right triangles : Arithmetic mean not on S. Tanvi Jain. Averaging operations on matrices ...

  3. Averaging operations on matrices

    Indian Academy of Sciences (India)

    2014-07-03

    Jul 3, 2014 ... flow at each voxel of brain scan. • Elasticity: 6 × 6 pd matrices model stress tensors. • Machine Learning: n × n pd matrices occur as kernel matrices. ... then the expected extension of geometric mean A1/2B1/2 is not even self-adjoint, leave alone positive definite. Tanvi Jain. Averaging operations on matrices ...

  4. Step-to-Step Ankle Inversion/Eversion Torque Modulation Can Reduce Effort Associated with Balance

    Directory of Open Access Journals (Sweden)

    Myunghee Kim

    2017-11-01

    Full Text Available Below-knee amputation is associated with higher energy expenditure during walking, partially due to difficulty maintaining balance. We previously found that once-per-step push-off work control can reduce balance-related effort, both in simulation and in experiments with human participants. Simulations also suggested that changing ankle inversion/eversion torque on each step, in response to changes in body state, could assist with balance. In this study, we investigated the effects of ankle inversion/eversion torque modulation on balance-related effort among amputees (N = 5 using a multi-actuated ankle-foot prosthesis emulator. In stabilizing conditions, changes in ankle inversion/eversion torque were applied so as to counteract deviations in side-to-side center-of-mass acceleration at the moment of intact-limb toe off; higher acceleration toward the prosthetic limb resulted in a corrective ankle inversion torque during the ensuing stance phase. Destabilizing controllers had the opposite effect, and a zero gain controller made no changes to the nominal inversion/eversion torque. To separate the balance-related effects of step-to-step control from the potential effects of changes in average mechanics, average ankle inversion/eversion torque and prosthesis work were held constant across conditions. High-gain stabilizing control lowered metabolic cost by 13% compared to the zero gain controller (p = 0.05. We then investigated individual responses to subject-specific stabilizing controllers following an enforced exploration period. Four of five participants experienced reduced metabolic rate compared to the zero gain controller (−15, −14, −11, −6, and +4% an average reduction of 9% (p = 0.05. Average prosthesis mechanics were unchanged across all conditions, suggesting that improvements in energy economy might have come from changes in step-to-step corrections related to balance. Step-to-step modulation of inversion/eversion torque could be

  5. Tailoring spin-orbit torque in diluted magnetic semiconductors

    KAUST Repository

    Li, Hang

    2013-05-16

    We study the spin orbit torque arising from an intrinsic linear Dresselhaus spin-orbit coupling in a single layer III-V diluted magnetic semiconductor. We investigate the transport properties and spin torque using the linear response theory, and we report here: (1) a strong correlation exists between the angular dependence of the torque and the anisotropy of the Fermi surface; (2) the spin orbit torque depends nonlinearly on the exchange coupling. Our findings suggest the possibility to tailor the spin orbit torque magnitude and angular dependence by structural design.

  6. Average is Over

    Science.gov (United States)

    Eliazar, Iddo

    2018-02-01

    The popular perception of statistical distributions is depicted by the iconic bell curve which comprises of a massive bulk of 'middle-class' values, and two thin tails - one of small left-wing values, and one of large right-wing values. The shape of the bell curve is unimodal, and its peak represents both the mode and the mean. Thomas Friedman, the famous New York Times columnist, recently asserted that we have entered a human era in which "Average is Over" . In this paper we present mathematical models for the phenomenon that Friedman highlighted. While the models are derived via different modeling approaches, they share a common foundation. Inherent tipping points cause the models to phase-shift from a 'normal' bell-shape statistical behavior to an 'anomalous' statistical behavior: the unimodal shape changes to an unbounded monotone shape, the mode vanishes, and the mean diverges. Hence: (i) there is an explosion of small values; (ii) large values become super-large; (iii) 'middle-class' values are wiped out, leaving an infinite rift between the small and the super large values; and (iv) "Average is Over" indeed.

  7. Manipulation of spin transfer torque using light

    Science.gov (United States)

    Rontani, Massimo; Vendelbjerg, Karsten; Sham, Lu

    We show that the spin transfer torque induced by a spin-polarized current on a nanomagnet as the current flows through a semiconductor-nanomagnet-semiconductor junction is externally controlled by shining the junction off-resonantly with a strong laser beam. The excitonic coherence driven by the laser dresses the virtual electron-hole pairs coupling conduction and valence bands and inducing an evanescent state in the proximity of the nanomagnet. The Fano-like quantum interference between this localized state and the continuum spectrum is different in the two spin channels and hence it dramatically alters the spin transport, leading to the coherent control of the spin transfer torque. This work is supported by EU-FP7 Marie Curie Initial Training Network INDEX.

  8. Spin diffusion and torques in disordered antiferromagnets

    KAUST Repository

    Manchon, Aurelien

    2017-02-01

    We have developed a drift-diffusion equation of spin transport in collinear bipartite metallic antiferromagnets. Starting from a model tight-binding Hamiltonian, we obtain the quantum kinetic equation within Keldysh formalism and expand it to the lowest order in spatial gradient using Wigner expansion method. In the diffusive limit, these equations track the spatio-temporal evolution of the spin accumulations and spin currents on each sublattice of the antiferromagnet. We use these equations to address the nature of the spin transfer torque in (i) a spin-valve composed of a ferromagnet and an antiferromagnet, (ii) a metallic bilayer consisting of an antiferromagnet adjacent to a heavy metal possessing spin Hall effect, and in (iii) a single antiferromagnet possessing spin Hall effect. We show that the latter can experience a self-torque thanks to the non-vanishing spin Hall effect in the antiferromagnet.

  9. Static magnetic forces and torques in ATLAS

    International Nuclear Information System (INIS)

    Morozov, N.A.; Samsonov, E.V.; Vorozhtsov, S.B.

    1998-01-01

    The magnetic forces acting on the various metallic objects around the ATLAS detector, are the subject of the given paper. A system designer could use the information on global forces and torque acting on various components, obtained in this report, to optimize them. The results of force calculations could also serve as additional criteria for the replacement of the magnetic baseline material of various structures by nonmagnetic ones

  10. An ironless armature brushless torque motor

    Science.gov (United States)

    Studer, P. A.

    1973-01-01

    A high torque motor with improved servo mechanism is reported. Armature windings are cast into an epoxy cylinder and armature conductors are integrally cast with an aluminum mounting ring which provides thermal conductance directly into the structure. This configuration eliminates magnetic hysteresis because there is no relative motion between the rotating magnetic field and any stationary iron. The absence of destabilization forces provides a fast electrical response compared with a typical torquer of conventional construction.

  11. Magnetorheological torque transmission devices with permanent magnets

    Science.gov (United States)

    Böse, H.; Gerlach, T.; Ehrlich, J.

    2013-02-01

    A novel type of magnetorheological (MR) clutch whose magnetic circuit contains a combination of a permanent magnet and an electromagnet is described. Without the support of the electromagnet, the permanent magnet generates a magnetic field in the MR fluid shear gap which enables the MR clutch to transmit a torque without the supply of any electric energy. Hence, the operational states of this clutch are reversed with respect to the common MR clutches equipped with an electromagnet only. Three different MR clutches with hybrid magnetic circuits containing permanent magnet and electromagnet were designed, manufactured and tested. The three clutches differ in their number of mechanical parts which can rotate with respect to each other as well as in their size and weight and in their maximum transmittable torque. The largest MR clutch is capable to transmit torques up to nearly 800 Nm. The designs of the three novel MR clutches and the results of the mechanical tests upon variation of the coil current are presented in this paper.

  12. Real time implementation of viable torque and flux controllers and torque ripple minimization algorithm for induction motor drive

    International Nuclear Information System (INIS)

    Vasudevan, M.; Arumugam, R.; Paramasivam, S.

    2006-01-01

    Field oriented control (FOC) and direct torque control (DTC) are becoming the industrial standards for induction motors torque and flux control. This paper aims to give a contribution for a detailed comparison between these two control techniques, emphasizing their advantages and disadvantages. The performance of these two control schemes is evaluated in terms of torque and flux ripple and their transient response to step variations of the torque command. Moreover, a new torque and flux ripple minimization technique is also proposed to improve the performance of the DTC drive. Based on the experimental results, the analysis has been presented

  13. Americans' Average Radiation Exposure

    International Nuclear Information System (INIS)

    2000-01-01

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body

  14. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    2001-01-01

    In this paper two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very often the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...... to a non-linear manifold and re-normalization or orthogonalization must be applied to obtain proper rotations. These latter steps have been viewed as ad hoc corrections for the errors introduced by assuming a vector space. The article shows that the two approximative methods can be derived from natural...... approximations to the Riemannian metric, and that the subsequent corrections are inherent in the least squares estimation....

  15. Bevel gear driver and method having torque limit selection

    Science.gov (United States)

    Cook, Joseph S., Jr.

    1994-08-01

    This invention comprises a torque drive mechanism utilizing axially translatable, mutually engageable transmission members having mating crown gears, driven and driving members with a three-element drive train being biased together by resilient means or by a fluid actuator system, the apparatus being operable to transmit a precisely controlled degree of torque to a driven member. The apparatus is applicable for use in hand tools and as a replacement for impact torque drivers, torque wrenches, motorized screw drivers, or the like, wherein the applied torque must be precisely controlled or limited. The bevel torque drive includes a drive gear which is axially displaceable and rotatable within cylindrical driver housing, a rotatable intermediate gear, and an output gear. Key rotationally secures displaceable gear with respect to input shaft but permits axial movement therebetween. A thrust bearing is preferably connected to the lower end of shaft for support to reduce play and friction between shaft and a transmission joint disc during rotation of the gear train. Coaxially mounted coiled spring is footed against displaceable gear for biasing the displaceable gear toward and into engagement with the intermediate gear for driving intermediate gear and output gear. Torque control is achieved by the use of straight or spiral beveled gears which are of configurations adapted to withdraw from mutual engagement upon the torque exceeding a predetermined limit. The novel, advantageous features of the invention include the configuration of the mating, crown gear sets and the axially translatable, slidable drive gear. The mechanism is capable of transmitting a high degree of torque within a narrow, compact transmission housing. The compact size and narrow, elongated configuration of the housing is particularly applicable for use in hand tools and in multiple torque driver mechanisms in which it is necessary to drive multiple fasteners which are located in close proximity. Prior

  16. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers.

    Science.gov (United States)

    van Oene, Maarten M; Dickinson, Laura E; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H

    2017-03-07

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor's response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor's performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level.

  17. Durability investigation on torque control of a magneto-rheological brake: experimental work

    Science.gov (United States)

    Kim, Wan Ho; Park, Jhin Ha; Kim, Gi-Woo; Shin, Cheol Soo; Choi, Seung-Bok

    2017-03-01

    This study experimentally investigates the torque control durability of a disc brake featuring a magneto-rheological (MR) fluid. An appropriate size of MR disc brake is designed based on a mathematical model, and a prototype is manufactured. A small-scale laboratory-scale test bed is then developed using a DC motor, in-line torque sensor, and the MR brake. S45C and S20C steels are inserted into a tapered hole on the surface of the brake disc. After 105 cycles of operation in shear mode, the wear properties of the MR brake are characterized by average surface roughness measurements, scanning electron microscope images, and energy dispersive x-ray spectra. The torque control performances before and after the operation cycles are examined using open-loop control and closed-loop proportional-integral-derivative control. As expected, the control performance degraded after 105 cycles of operation in the open-loop case, but not in the closed-loop case. This aspect is demonstrated by the sinusoidal torque-tacking control performance before and after the operation cycles.

  18. Analytical description of ballistic spin currents and torques in magnetic tunnel junctions

    KAUST Repository

    Chshiev, M.

    2015-09-21

    In this work we demonstrate explicit analytical expressions for both charge and spin currents which constitute the 2×2 spinor in magnetic tunnel junctions with noncollinear magnetizations under applied voltage. The calculations have been performed within the free electron model in the framework of the Keldysh formalism and WKB approximation. We demonstrate that spin/charge currents and spin transfer torques are all explicitly expressed through only three irreducible quantities, without further approximations. The conditions and mechanisms of deviation from the conventional sine angular dependence of both spin currents and torques are shown and discussed. It is shown in the thick barrier approximation that all tunneling transport quantities can be expressed in an extremely simplified form via Slonczewski spin polarizations and our effective spin averaged interfacial transmission probabilities and effective out-of-plane polarizations at both interfaces. It is proven that the latter plays a key role in the emergence of perpendicular spin torque as well as in the angular dependence character of all spin and charge transport considered. It is demonstrated directly also that for any applied voltage, the parallel component of spin current at the FM/I interface is expressed via collinear longitudinal spin current components. Finally, spin transfer torque behavior is analyzed in a view of transverse characteristic length scales for spin transport.

  19. Applying torque to the Escherichia coli flagellar motor using magnetic tweezers

    Science.gov (United States)

    van Oene, Maarten M.; Dickinson, Laura E.; Cross, Bronwen; Pedaci, Francesco; Lipfert, Jan; Dekker, Nynke H.

    2017-01-01

    The bacterial flagellar motor of Escherichia coli is a nanoscale rotary engine essential for bacterial propulsion. Studies on the power output of single motors rely on the measurement of motor torque and rotation under external load. Here, we investigate the use of magnetic tweezers, which in principle allow the application and active control of a calibrated load torque, to study single flagellar motors in Escherichia coli. We manipulate the external load on the motor by adjusting the magnetic field experienced by a magnetic bead linked to the motor, and we probe the motor’s response. A simple model describes the average motor speed over the entire range of applied fields. We extract the motor torque at stall and find it to be similar to the motor torque at drag-limited speed. In addition, use of the magnetic tweezers allows us to force motor rotation in both forward and backward directions. We monitor the motor’s performance before and after periods of forced rotation and observe no destructive effects on the motor. Our experiments show how magnetic tweezers can provide active and fast control of the external load while also exposing remaining challenges in calibration. Through their non-invasive character and straightforward parallelization, magnetic tweezers provide an attractive platform to study nanoscale rotary motors at the single-motor level. PMID:28266562

  20. Efficiency improvement and torque ripple minimization of Switched Reluctance Motor using FEM and Seeker Optimization Algorithm

    International Nuclear Information System (INIS)

    Navardi, Mohammad Javad; Babaghorbani, Behnaz; Ketabi, Abbas

    2014-01-01

    Highlights: • This paper proposes a new method to optimize a Switched Reluctance Motor (SRM). • A combination of SOA and GA with Finite Element Method (FEM) analysis is employed to solve the SRM design optimization. • The results show that optimized SRM obtains higher average torque and higher efficiency. - Abstract: In this paper, performance optimization of Switched Reluctance Motor (SRM) was determined using Seeker Optimization Algorithm (SOA). The most efficient aim of the algorithm was found for maximum torque value at a minimum mass of the entire construction, following changing the geometric parameters. The optimization process was carried out using a combination of Seeker Optimization Algorithm and Finite Element Method (FEM). Fitness value was calculated by FEM analysis using COMSOL3.4, and the SOA was realized by MATLAB. The proposed method has been applied for a case study and it has been also compared with Genetic Algorithm (GA). The results show that the optimized motor using SOA had higher torque value and efficiency with lower mass and torque ripple, exhibiting the validity of this methodology for SRM design

  1. Robust spin transfer torque in antiferromagnetic tunnel junctions

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2017-04-18

    We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling electrical manipulation of the Néel antiferromagnetic order parameter is out of plane, ∼n×p, while the torque competing with the antiferromagnetic exchange is in plane, ∼n×(p×n). Here, p and n are the Néel order parameter direction of the reference and free layers, respectively. Their bias dependence shows behavior similar to that in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias, while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than that in antiferromagnetic metallic spin valves due to the tunneling nature of spin transport.

  2. Factor Analysis on Cogging Torques in Segment Core Motors

    Science.gov (United States)

    Enomoto, Yuji; Kitamura, Masashi; Sakai, Toshihiko; Ohara, Kouichiro

    The segment core method is a popular method employed in motor core manufacturing; however, this method does not allow the stator core precision to be enhanced because the stator is assembled from many cores. The axial eccentricity of rotor and stator and the internal roundness of the stator core are regarded as the main factors which affect cogging torque. In the present study, the way in which a motor with a split-type stator generates a cogging torque is investigated to determine whether high- precision assembly of stator cores can reduce cogging torque. Here, DC brushless motors were used to verify the influence of stator-rotor eccentricity and roundness of the stator bore on cogging torque. The evaluation results prove the feasibility of reducing cogging torque by improving the stator core precision. Therefore, improving the eccentricity and roundness will enable stable production of well controlled motors with few torque ripples.

  3. Direct Torque Control of Matrix Converter Fed Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    JAGADEESAN Karpagam

    2011-10-01

    Full Text Available This paper presents the Direct TorqueControl (DTC of induction motor drive using matrixconverters. DTC is a high performance motor controlscheme with fast torque and flux responses. However,the main disadvantage of conventional DTC iselectromagnetic torque ripple. In this paper, directtorque control for Induction Motors using MatrixConverters is analysed and points out the problem ofthe electromagnetic torque ripple which is one of themost important drawbacks of the Direct TorqueControl. Besides, the matrix converter is a single-stageac-ac power conversion device without dc-link energystorage elements. Matrix converter (MC may becomea good alternative to voltage-source inverter (VSI.This work combines the advantages of the matrixconverter with those of the DTC technique, generatingthe required voltage vectors under unity input powerfactor operation. Simulation results demonstrates theeffectiveness of the torque control.

  4. Cantilever torque magnetometry on coordination compounds

    DEFF Research Database (Denmark)

    Perfetti, Mauro

    2017-01-01

    Cantilever Torque Magnetometry (CTM) is one of the leading techniques to deeply understand magnetic anisotropy of coordination compounds. The knowledge of magnetic anisotropy is a mandatory requirement before proceeding with any future application related to the magnetic properties of coordination...... quantum phenomena such as magnetization steps and molecular hysteresis curves. Moreover, it can also provide the energy levels splitting and avefunctions composition, especially if coupled with microwave radiation....... compounds, such as quantum computation or information storage. This review enlightens that CTM offers a unique combination of accuracy and precision to disentangle noncollinear contributions inside Single Crystals as well as the sensitivity to detect molecular order of thin films. CTM can also detect...

  5. Motor Torque Calculations For Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Saurabh Chauhan

    2015-08-01

    Full Text Available Abstract It is estimated that 25 of the total cars across the world will run on electricity by 2025. An important component that is an integral part of all electric vehicles is the motor. The amount of torque that the driving motor delivers is what plays a decisive role in determining the speed acceleration and performance of an electric vehicle. The following work aims at simplifying the calculations required to decide the capacity of the motor that should be used to drive a vehicle of particular specifications.

  6. Muscle torque preservation and physical activity in individuals with stroke.

    Science.gov (United States)

    Eng, Janice J; Lomaglio, Melanie J; Macintyre, Donna L

    2009-07-01

    A greater percent loss of concentric versus eccentric muscle torque (i.e., relative eccentric muscle torque preservation) has been reported in the paretic limb of individuals with stroke and has been attributed to hypertonia and/or cocontractions. Stroke provides a unique condition for examining mechanisms underlying eccentric muscle preservation because both limbs experience similar amounts of general physical activity, but the paretic side is impaired directly by the brain lesion. The purpose of this study was to determine 1) whether eccentric preservation also exists in the nonparetic limb and 2) the relationship of eccentric or concentric torque preservation with physical activity in stroke. We hypothesized that the nonparetic muscles would demonstrate eccentric muscle preservation, which would suggest that nonneural mechanisms may also contribute to its relative preservation. Eighteen patients who had stroke and 18 healthy control subjects (age- and sex-matched) completed a physical activity questionnaire. Maximum voluntary concentric and eccentric joint torques of the ankle, knee, and hip flexors and extensors were measured using an isokinetic dynamometer at 30 degrees x s(-1) for the paretic and nonparetic muscles. Relative concentric and eccentric peak torque preservations were expressed as a percentage of control subject torque. Relative eccentric torque was higher (more preserved) than relative concentric torque for paretic and nonparetic muscles. Physical activity correlated with paretic (r = 0.640, P = 0.001) and nonparetic concentric torque preservation (r = 0.508, P = 0.009) but not with eccentric torque preservation for either leg. The relative preservation of eccentric torque in the nonparetic muscles suggest a role of nonneural mechanisms and could also explain the preservation observed in other chronic health conditions. Loss of concentric, but not eccentric, muscle torque was related to physical inactivity in stroke.

  7. A New Circuit Model for Spin-Torque Oscillator Including Perpendicular Torque of Magnetic Tunnel Junction

    Directory of Open Access Journals (Sweden)

    Hyein Lim

    2013-01-01

    Full Text Available Spin-torque oscillator (STO is a promising new technology for the future RF oscillators, which is based on the spin-transfer torque (STT effect in magnetic multilayered nanostructure. It is expected to provide a larger tunability, smaller size, lower power consumption, and higher level of integration than the semiconductor-based oscillators. In our previous work, a circuit-level model of the giant magnetoresistance (GMR STO was proposed. In this paper, we present a physics-based circuit-level model of the magnetic tunnel junction (MTJ-based STO. MTJ-STO model includes the effect of perpendicular torque that has been ignored in the GMR-STO model. The variations of three major characteristics, generation frequency, mean oscillation power, and generation linewidth of an MTJ-STO with respect to the amount of perpendicular torque, are investigated, and the results are applied to our model. The operation of the model was verified by HSPICE simulation, and the results show an excellent agreement with the experimental data. The results also prove that a full circuit-level simulation with MJT-STO devices can be made with our proposed model.

  8. Maximum insertion torque of a novel implant-abutment-interface design for PEEK dental implants.

    Science.gov (United States)

    Schwitalla, Andreas Dominik; Zimmermann, Tycho; Spintig, Tobias; Abou-Emara, Mohamed; Lackmann, Justus; Müller, Wolf-Dieter; Houshmand, Alireza

    2018-01-01

    Frequent reports attest to the various advantages of tapered implant/abutment interfaces (IAIs) compared to other types of interfaces. For this reason, a conical IAI was designed as part of the development of a PEEK (polyetheretherketone)-based dental implant. This IAI is equipped with an apically displaced anti-rotation lock with minimal space requirements in the form of an internal spline. The objective of this study was the determination of the average insertion torque (IT) at failure of this design, so as to determine its suitability for immediate loading, which requires a minimum IT of 32Ncm. 10 implants each made of unfilled PEEK, carbon fiber reinforced ("CFR") PEEK (> 50vol% continuous axially parallel fibers) as well as of titanium were produced and tested in a torque test bench. The average IT values at failure of the unfilled PEEK implants were measured at 22.6 ± 0.5Ncm and were significantly higher than those of the CFR-Implants (20.2 ± 2.5Ncm). The average IT values at failure of the titanium specimens were significantly higher (92.6 ± 2.3Ncm) than those of the two PEEK variants. PEEK- and CFR-PEEK-implants in the present form cannot adequately withstand the insertion force needed to achieve primary stability for immediate loading. Nevertheless, the achievable torque resilience of the two PEEK-variants may be sufficient for a two-stage implantation procedure. To improve the torque resistance of the PEEK implant material the development of a new manufacturing procedure is necessary which reinforces the PEEK base with continuous multi-directional carbon fibers as opposed to the axially parallel fibers of the tested PEEK compound. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Spin-orbit torques in magnetic bilayers

    Science.gov (United States)

    Haney, Paul

    2015-03-01

    Spintronics aims to utilize the coupling between charge transport and magnetic dynamics to develop improved and novel memory and logic devices. Future progress in spintronics may be enabled by exploiting the spin-orbit coupling present at the interface between thin film ferromagnets and heavy metals. In these systems, applying an in-plane electrical current can induce magnetic dynamics in single domain ferromagnets, or can induce rapid motion of domain wall magnetic textures. There are multiple effects responsible for these dynamics. They include spin-orbit torques and a chiral exchange interaction (the Dzyaloshinskii-Moriya interaction) in the ferromagnet. Both effects arise from the combination of ferromagnetism and spin-orbit coupling present at the interface. There is additionally a torque from the spin current flux impinging on the ferromagnet, arising from the spin hall effect in the heavy metal. Using a combination of approaches, from drift-diffusion to Boltzmann transport to first principles methods, we explore the relative contributions to the dynamics from these different effects. We additionally propose that the transverse spin current is locally enhanced over its bulk value in the vicinity of an interface which is oriented normal to the charge current direction.

  10. Analysis of the Torque Ripples in Designing a Disk Type Brushless Direct Current Motor

    Directory of Open Access Journals (Sweden)

    A. V. Stepanov

    2015-01-01

    Full Text Available This paper investigates the torque ripples of disk-type low-power brushless direct current motor (BDCM with permanent magnets. In spite of numerous studies on designing of valve engines this issue is understudied as yet. The torque ripples cause noise and vibration and can significantly limit accuracy when used in instrumentation, computer technology.We consider a motor that includes a power unit consisting of a rotor and a stator. There are ferrite elements of sensor on the rotor, and the nonmagnetic disk, bonded to it, contains permanent magnets. The rotor is mounted on a rotating shaft. The stator consists of a steel casing and bonded to it non-magnetic, non-conductive disk with holes. In the disk holes from both sides are mounted armature coils. The armature winding consists of two sections each of which has 6 coils. Each adjacent coil in section has an opposite direction of winding. The coils are arranged circumferentially and are shifted relative to each other; the displacement angle between the coils of one section is equal to 2π/6 (rad. Sections are also shifted relative to each other; the angular shift is π/6 (rad. Sections are connected to the output terminals of the electronic switch. Sections of motor windings have the reverse full-wave power.The paper has investigated the steady operation at four-stroke switching and under constant load (torque. In this case, the electromagnetic torque and rotor speed are periodical functions of the rotor rotation angle. The dependencies of the averaged torque on the rotation speed have been obtained. The spectral distribution of the torque ripples at various rotor speeds of rotation has been calculated. The dependencies of the torque on the speed were studied both at constant speed and taking into account the uneven speed. Based on the research findings of disk type BDCM was computed a level of ripples amounted to 0.8 - 5%, which is quite acceptable for use in a drive. The results are useful for

  11. Smooth torque speed characteristic of switched reluctance motors

    DEFF Research Database (Denmark)

    Zeng, Hui; Chen, Zhe; Chen, Hao

    2014-01-01

    The torque ripple of switched reluctance motors (SRMs) is the main disadvantage that limits the industrial application of these motors. Although several methods for smooth-toque operation (STO) have been proposed, STO works well only within a certain torque and speed range because...

  12. Improvement of Torque Production in Single-Phase Induction Motors ...

    African Journals Online (AJOL)

    Existing single phase induction motors exhibit low starting torque. Moreover, during accelerating time and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM ...

  13. Direct torque control with feedback linearization for induction motor drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Jafarzadeh, Saeed; Fadali, Sami M.

    2015-01-01

    This paper describes a Direct Torque Controlled (DTC) Induction Machine (IM) drive that employs feedback linearization and sliding-mode control. A feedback linearization approach is investigated, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude...

  14. Improvement of Torque Production in Single-Phase Induction Motors

    African Journals Online (AJOL)

    OLUWASOGO

    PID controller. Simulation results show the starting torque of the motor increased by 75% under the developed drive scheme. In addition, torque pulsations reduced from 1.4 Nm peak-peak to 0.14 Nm peak-peak at steady state. It was observed that the accelerating time reduced by 30% compared to the accelerating time ...

  15. Improving the performance of hysteresis direct torque control of ...

    Indian Academy of Sciences (India)

    Many other researchers used filter topologies to improve waveform in PMSM. Sozer et al. (2000) have presented an ... In this study, a new filter topology is proposed to reduce torque ripples and voltage harmonic noises in IPMSM with direct torque .... The IPMSM is star-connected with earth return. The motor parameters are ...

  16. 14 CFR 27.397 - Limit pilot forces and torques.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit pilot forces and torques. 27.397... System Loads § 27.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick controls...

  17. 14 CFR 29.397 - Limit pilot forces and torques.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit pilot forces and torques. 29.397... System Loads § 29.397 Limit pilot forces and torques. (a) Except as provided in paragraph (b) of this section, the limit pilot forces are as follows: (1) For foot controls, 130 pounds. (2) For stick controls...

  18. Spin-torque generation in topological insulator based heterostructures

    KAUST Repository

    Fischer, Mark H.

    2016-03-11

    Heterostructures utilizing topological insulators exhibit a remarkable spin-torque efficiency. However, the exact origin of the strong torque, in particular whether it stems from the spin-momentum locking of the topological surface states or rather from spin-Hall physics of the topological-insulator bulk, remains unclear. Here, we explore a mechanism of spin-torque generation purely based on the topological surface states. We consider topological-insulator-based bilayers involving ferromagnetic metal (TI/FM) and magnetically doped topological insulators (TI/mdTI), respectively. By ascribing the key theoretical differences between the two setups to location and number of active surface states, we describe both setups within the same framework of spin diffusion of the nonequilibrium spin density of the topological surface states. For the TI/FM bilayer, we find large spin-torque efficiencies of roughly equal magnitude for both in-plane and out-of-plane spin torques. For the TI/mdTI bilayer, we elucidate the dominance of the spin-transfer-like torque. However, we cannot explain the orders of magnitude enhancement reported. Nevertheless, our model gives an intuitive picture of spin-torque generation in topological-insulator-based bilayers and provides theoretical constraints on spin-torque generation due to topological surface states.

  19. Coorbital thermal torques on low-mass protoplanets

    Science.gov (United States)

    Masset, Frédéric S.

    2017-12-01

    Using linear perturbation theory, we investigate the torque exerted on a low-mass planet embedded in a gaseous protoplanetary disc with finite thermal diffusivity. When the planet does not release energy into the ambient disc, the main effect of thermal diffusion is the softening of the enthalpy peak near the planet, which results in the appearance of two cold and dense lobes on either side of the orbit, of size smaller than the thickness of the disc. The lobes exert torques of opposite sign on the planet, each comparable in magnitude to the one-sided Lindblad torque. When the planet is offset from corotation, the lobes are asymmetric and the planet experiences a net torque, the 'cold' thermal torque, which has a magnitude that depends on the relative value of the distance to corotation to the size of the lobes ˜√{χ /Ω _p}, χ being the thermal diffusivity and Ωp the orbital frequency. We believe that this effect corresponds to the phenomenon named 'cold finger' recently reported in numerical simulations, and we argue that it constitutes the dominant mode of migration of sub-Earth-mass objects. When the planet is luminous, the heat released into the ambient disc results in an additional disturbance that takes the form of hot, low-density lobes. They give a torque, named heating torque in previous work, that has an expression similar, but of opposite sign, to the cold thermal torque.

  20. Effects of fatiguing constant versus alternating intensity intermittent isometric muscle actions on maximal torque and neuromuscular responses.

    Science.gov (United States)

    Smith, C M; Housh, T J; Hill, E C; Cochrane, K C; Jenkins, N Dm; Schmidt, R J; Johnson, G O

    2016-12-14

    To determine the effects of constant versus alternating applications of torque during fatiguing, intermittent isometric muscle actions of the leg extensors on maximal voluntary isometric contraction (MVIC) torque and neuromuscular responses. Sixteen subjects performed two protocols, each consisting of 50 intermittent isometric muscle actions of the leg extensors with equal average load at a constant 60% MVIC or alternating 40 then 80% (40/80%) MVIC with a work-to-rest ratio of 6-s on and 2-s off. MVIC torque as well as electromyographic signals from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) and mechanomyographic signals from the VL were recorded pretest, immediately posttest, and 5-min posttest. The results indicated that there were no time-related differences between the 60% MVIC and 40/80% MVIC protocols. The MVIC torque decreased posttest (22 to 26%) and remained depressed 5-min posttest (9%). There were decreases in electromyographic frequency (14 to 19%) and mechanomyographic frequency (23 to 24%) posttest that returned to pretest levels 5-min posttest. There were no changes in electromyographic amplitude and mechanomyogrpahic amplitude. These findings suggested that these neuromuscular parameters did not track the fatigue-induced changes in MVIC torque after 5-min of recovery.

  1. Alternating bending-steady torque fatigue reliability

    Science.gov (United States)

    Kececioglu, D.; Chester, L. B.; Dodge, T. M.

    1974-01-01

    Results generated by three unique fatigue reliability research machines which can apply alternating-bending loads combined with steady torque are presented. Six-inch long, AISI steel, grooved specimens with a stress concentration factor of 1.42 and Rockwell C 35/40 hardness were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and staircase-testing data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one best represents the data. The effect of the groove and of the various combined bending-torsion loads on the finite and endurance life strength of such components, as well as on the Goodman diagram, are determined. Design applications are presented.

  2. Manipulating spin transfer torque with light

    Science.gov (United States)

    Vendelbjerg, Karsten Leding; Rontani, Massimo

    2017-08-01

    We study the spin transfer torque (STT) induced onto a nanomagnet as a spin-polarized current flows through a junction made of the magnet sandwiched between two semiconductors. This junction is one-dimensional and highly idealized, the thin magnetic layer being mimicked by a spin-dependent contact force. We show that the STT may be externally controlled by shining the junction at sub-bandgap frequency with an intense laser beam. The excitonic coherence driven by the laser dresses the virtual electron-hole pairs coupling conduction and valence bands and inducing evanescent waves at the junction interface. The Fano-like quantum interference between these localized states and the continuum spectrum, being different in the two spin channels, significantly affects the STT.

  3. Torque compensation technology for the geostationary meteorological satellite

    Science.gov (United States)

    Wang, Zhigang; Wang, Lusha; Chen, Shilu; Li, Qing

    2009-12-01

    To acquire high quality image, the new generation Geostationary Meteorological Satellite in China (GMSC) adopts three-axis stabilized attitude control mode, besides an advanced control system is required to be designed to get higher pointing precision and degree of stability of the satellite. However, the ability of the control system is limited. Torque compensation technology is studied in this paper aiming at rejecting the disturbance factors, which cannot be absorbed by the control system. In the research of torque compensation technology, the main factors that influence the degree of stability of satellite are analyzed; the objects compensated are confirmed through analysis of simulation; the system technical concept of torque compensation is designed; the mathematical models of the compensated objects and compensation devices are founded; the torque compensation arithmetic is designed; the valid arithmetic of torque compensation is proved through simulation. The research provides theoretical principles to develop the new generation GMSC.

  4. Special-Purpose High-Torque Permanent-Magnet Motors

    Science.gov (United States)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  5. Active element influence on the motor’s torque

    Directory of Open Access Journals (Sweden)

    Dolgih Antonina

    2017-01-01

    Full Text Available The paper presents the numerical and experimental studies of the influence of the torque motor active element on the motor’s torque. The tape active element is a novel type of a motor’s stator organization, where the conventional winding is replaced by a tape winding. The force (torque dependence over the rotor pole position using COMSOL is given; the tape winding resistance and the turns number are defined. The relative motor’s characteristics are investigated and the maximum torque over the certain poles pair number is obtained. The application of the proposed active element in brushless DC motor is considered. The results show the possibility of the further synthesis of the torque motor.

  6. Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

    Science.gov (United States)

    Markley, F. Landis; Reynolds, Reid G.; Liu, Frank X.; Lebsock, Kenneth L.

    2009-01-01

    Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum that the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical strategies for distributing a prescribed torque or momentum among the n wheels are presented, with special emphasis on configurations of four, five, and six wheels.

  7. Spin-wave-induced spin torque in Rashba ferromagnets

    Science.gov (United States)

    Umetsu, Nobuyuki; Miura, Daisuke; Sakuma, Akimasa

    2015-05-01

    We study the effects of Rashba spin-orbit coupling on the spin torque induced by spin waves, which are the plane-wave dynamics of magnetization. The spin torque is derived from linear-response theory, and we calculate the dynamic spin torque by considering the impurity-ladder-sum vertex corrections. This dynamic spin torque is divided into three terms: a damping term, a distortion term, and a correction term for the equation of motion. The distorting torque describes a phenomenon unique to the Rashba spin-orbit coupling system, where the distorted motion of magnetization precession is subjected to the anisotropic force from the Rashba coupling. The oscillation mode of the precession exhibits an elliptical trajectory, and the ellipticity depends on the strength of the nesting effects, which could be reduced by decreasing the electron lifetime.

  8. Comparison of concentric isokinetic dominant shoulder internal and external rotator torque between professional female volleyball and tennis players

    Directory of Open Access Journals (Sweden)

    S. Talebian

    2006-08-01

    Full Text Available Background: The purpose of this study was to measure isokinetic maximum and average peak torque of internal and external rotators of glenohumeral joint in volley ball and tennis players Methods: This study was performed on 17 professional female athletes (7 tennis players &10 volleyball players with age ranged 18-28 years. The subjects had played in a skilled team for more than 3 years. They were free from injury to their dominant shoulder in the past year. Subjects performed a five minute warm up by shoulder wheel and Maximum average Peak Torque (APT were obtained unilaterally by a Biodex System 3 with the arm of players in 90 degree abduction at 120,180 & 210 o/s. Players performed five trails of concentric movements with 30 second rest between them. Results: Maximum and average of maximum torques of shoulder rotator, in both groups, expect for internal rotators of tennis players, reduced by increase of movement speed (P<0.05. There are not significant difference between two groups in maximum, average of maximum torques and normalized data (ratio of maximum torque to weight. There is significant difference between two groups in percentage of APT of External rotator / Internal rotator ratio at 210 o/s (P<0.05. Conclusion: Volleyball and tennis have no effect on isokinetic strength of shoulder rotators. In high speed, ratio of External rotator / Internal rotator is reduced. This indicates that increase in movement speed increase internal rotator in comparison to external rotator in these professional female athletes.

  9. Comparison of different passive knee extension torque-angle assessments

    International Nuclear Information System (INIS)

    Freitas, Sandro R; Vaz, João R; Bruno, Paula M; Valamatos, Maria J; Mil-Homens, Pedro

    2013-01-01

    Previous studies have used isokinetic dynamometry to assess joint torques and angles during passive extension of the knee, often without reporting upon methodological errors and reliability outcomes. In addition, the reliability of the techniques used to measure passive knee extension torque-angle and the extent to which reliability may be affected by the position of the subjects is also unclear. Therefore, we conducted an analysis of the intra- and inter-session reliability of two methods of assessing passive knee extension: (A) a 2D kinematic analysis coupled to a custom-made device that enabled the direct measurement of resistance to stretch and (B) an isokinetic dynamometer used in two testing positions (with the non-tested thigh either flexed at 45° or in the neutral position). The intra-class correlation coefficients (ICCs) of torque, the slope of the torque-angle curve, and the parameters of the mathematical model that were fit to the torque-angle data for the above conditions were measured in sixteen healthy male subjects (age: 21.4 ± 2.1 yr; BMI: 22.6 ± 3.3 kg m −2 ; tibial length: 37.4 ± 3.4 cm). The results found were: (1) methods A and B led to distinctly different torque-angle responses; (2) passive torque-angle relationship and stretch tolerance were influenced by the position of the non-tested thigh; and (3) ICCs obtained for torque were higher than for the slope and for the mathematical parameters that were fit to the torque-angle curve. In conclusion, the measurement method that is used and the positioning of subjects can influence the passive knee extension torque-angle outcome. (paper)

  10. In Vitro Measurement Of Insertion Torque, Removal Torque And Resonance Frequency Analysis Of Implants Placed Into Simulated Bony Defects

    Science.gov (United States)

    2014-05-14

    in predicting dental implant osseointegration and long-term success. Measurements of insertion torque, removal torque, and resonance frequency...gain faster osseointegration (Gustavo, Kelly 2009). Osseointegration A dental implant is regarded as osseointegrated when there is no...was completed by Perez in 2007 that evaluated the time evolution of the osseointegration process for a dental implant with regards to time and

  11. Correctional Facility Average Daily Population

    Data.gov (United States)

    Montgomery County of Maryland — This dataset contains Accumulated monthly with details from Pre-Trial Average daily caseload * Detention Services, Average daily population for MCCF, MCDC, PRRS and...

  12. Improvement of Torque Response and Examination of Sensorless Drive System Based on Direct Torque Control for IPMSM

    Science.gov (United States)

    Inoue, Yukinori; Morimoto, Shigeo; Sanada, Masayuki

    This paper examines the sensorless control system based on the direct torque control (DTC) for an interior permanent magnet synchronous motor (IPMSM). In the DTC system, the rotor position is not required, and the rotor speed is estimated from the estimated position of stator flux-linkage vector. In addition, the maximum torque per ampere (MTPA) control and the flux weakening (FW) control can be applied to the DTC as well as the current control method in the d-q reference frame. Therefore the DTC can operate over a wide speed range. The characteristic of the maximum power operation is shown by the experimental result. The torque response is investigated by the simulation and experimental results. A relationship between the controller gain and torque response is shown, and an improvement method of the torque response is proposed.

  13. Interaction torque contributes to planar reaching at slow speed

    Directory of Open Access Journals (Sweden)

    Hoshi Fumihiko

    2008-10-01

    Full Text Available Abstract Background How the central nervous system (CNS organizes the joint dynamics for multi-joint movement is a complex problem, because of the passive interaction among segmental movements. Previous studies have demonstrated that the CNS predictively compensates for interaction torque (INT which is arising from the movement of the adjacent joints. However, most of these studies have mainly examined quick movements, presumably because the current belief is that the effects of INT are not significant at slow speeds. The functional contribution of INT for multijoint movements performed in various speeds is still unclear. The purpose of this study was to examine the contribution of INT to a planer reaching in a wide range of motion speeds for healthy subjects. Methods Subjects performed reaching movements toward five targets under three different speed conditions. Joint position data were recorded using a 3-D motion analysis device (50 Hz. Torque components, muscle torque (MUS, interaction torque (INT, gravity torque (G, and net torque (NET were calculated by solving the dynamic equations for the shoulder and elbow. NET at a joint which produces the joint kinematics will be an algebraic sum of torque components; NET = MUS - G - INT. Dynamic muscle torque (DMUS = MUS-G was also calculated. Contributions of INT impulse and DMUS impulse to NET impulse were examined. Results The relative contribution of INT to NET was not dependent on speed for both joints at every target. INT was additive (same direction to DMUS at the shoulder joint, while in the elbow DMUS counteracted (opposed to INT. The trajectory of reach was linear and two-joint movements were coordinated with a specific combination at each target, regardless of motion speed. However, DMUS at the elbow was opposed to the direction of elbow movement, and its magnitude varied from trial to trial in order to compensate for the variability of INT. Conclusion Interaction torque was important at

  14. Temperature dependence of spin-orbit torques in Cu-Au alloys

    KAUST Repository

    Wen, Yan

    2017-03-07

    We investigated current driven spin-orbit torques in Cu40Au60/Ni80Fe20/Ti layered structures with in-plane magnetization. We have demonstrated a reliable and convenient method to separate dampinglike torque and fieldlike torque by using the second harmonic technique. It is found that the dampinglike torque and fieldlike torque depend on temperature very differently. Dampinglike torque increases with temperature, while fieldlike torque decreases with temperature, which are different from results obtained previously in other material systems. We observed a nearly linear dependence between the spin Hall angle and longitudinal resistivity, suggesting that skew scattering may be the dominant mechanism of spin-orbit torques.

  15. Slot deformation of various stainless steel bracket due to the torque force of the beta-titanium wire

    Science.gov (United States)

    Huda, M. M.; Siregar, E.; Ismah, N.

    2017-08-01

    Stainless steel bracket slot deformation ffects the force applied to teeth and it can impede tooth movement and prolong orthodontic treatment time. The aim of this study is to determine the slot deformation due to torque of a 0.021 × 0.025 inch Beta Titanium wire with a torsional angle of 30° and 45° for five different bracket brands: y, 3M, Biom, Versadent, Ormco, and Shinye. The research also aims to compare the deformation and amount of torque among all five bracket brands at torsional angles of 30° and 45°. Fifty stainless steel edgewise brackets from the five bracket group brands (n=10) were attached to acrylic plates. The bracket slot measurements were carried out in two stages. In the first stage, the, deformation was measured by calculating the average bracket slot height using a stereoscopy microscope before and after application of torque. In the second stage, the torque was measured using a torque measurement apparatus. The statistical analysis shows that slot deformations were found on all five bracket brands with a clinical permanent deformation on the Biom (2.79 μm) and Shinye (2.29 μm) brackets. The most torque was observed on the 3M bracket, followed by the Ormco, Versadent, Shinye, and Biom brackets. When the brands were compared, a correlation between bracket slot deformation and the amount of torque was found, but the correlation was not statistically significant for the 3M and Ormco brackets and the Biom and Shinye brackets. There is a difference in the amount of torque between the five brands with a torsional angle of 30° (except the 3M and Ormco brackets) and those with a torsional angle of 45°. The composition of the metal and the manufacturing process are the factors that influence the occurrence of bracket slot deformation and the amount of torque. A manufacturing process using metal injection molding (MIM) and metal compositions of AISI 303 and 17-4 PH stainless steel reduce the risk of deformation.

  16. The difference between alternative averages

    Directory of Open Access Journals (Sweden)

    James Vaupel

    2012-09-01

    Full Text Available BACKGROUND Demographers have long been interested in how compositional change, e.g., change in age structure, affects population averages. OBJECTIVE We want to deepen understanding of how compositional change affects population averages. RESULTS The difference between two averages of a variable, calculated using alternative weighting functions, equals the covariance between the variable and the ratio of the weighting functions, divided by the average of the ratio. We compare weighted and unweighted averages and also provide examples of use of the relationship in analyses of fertility and mortality. COMMENTS Other uses of covariances in formal demography are worth exploring.

  17. Evaluation of Hydrate Inhibition Performance of Water-soluble Polymers using Torque Measurement and Differential Scanning Calorimeter

    International Nuclear Information System (INIS)

    Shin, Kyuchul; Park, Juwoon; Kim, Jakyung; Kim, Hyunho; Seo, Yutaek; Lee, Yohan; Seo, Yongwon

    2014-01-01

    In this work, hydrate inhibition performance of water-soluble polymers including pyrrolidone, caprolactam, acrylamide types were evaluated using torque measurement and high pressure differential scanning calorimeter (HP µ-DSC). The obtained experimental results suggest that the studied polymers represent the kinetic hydrate inhibition (KHI) performance. 0.5 wt% polyvinylcaprolactam (PVCap) solution shows the hydrate onset time of 34.4 min and subcooling temperature of 15.9 K, which is better KHI performance than that of pure water - hydrate onset time of 12.3 min and subcooling temperature of 6.0 K. 0.5 wt% polyvinylpyrrolidone (PVP) solution shows the hydrate onset time of 27.6 min and the subcooling temperature of 13.2 K while polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA) solution shows less KHI performance than PVP solution at both 0.5 and 5.0 wt%. However, PAM-co-AA solution shows slow growth rate and low hydrate amount than PVCap. In addition to hydrate onset and growth condition, torque change with time was investigated as one of KHI evaluation methods. 0.5 wt% PVCap solution shows the lowest average torque of 6.4 N cm and 0.5 wt% PAM-co-AA solution shows the average torque of 7.2 N cm. For 0.5 wt% PVP solution, it increases 11.5 N cm and 5.0 wt% PAM-co-AA solution shows the maximum average torque of 13.4 N cm, which is similar to the average torque of pure water, 15.2 N cm. Judging from the experimental results obtained by both an autoclave and a HP µ-DSC, the PVCap solution shows the best performance among the KHIs in terms of delaying hydrate nucleation. From these results, it can be concluded that the torque change with time is useful to identify the flow ability of tested solution, and the further research on the inhibition of hydrate formation can be approached in various aspects using a HP µ-DSC

  18. Evaluation of Hydrate Inhibition Performance of Water-soluble Polymers using Torque Measurement and Differential Scanning Calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Kyuchul; Park, Juwoon; Kim, Jakyung; Kim, Hyunho; Seo, Yutaek [KAIST, Daejeon (Korea, Republic of); Lee, Yohan; Seo, Yongwon [UNIST, Ulsan (Korea, Republic of)

    2014-12-15

    In this work, hydrate inhibition performance of water-soluble polymers including pyrrolidone, caprolactam, acrylamide types were evaluated using torque measurement and high pressure differential scanning calorimeter (HP µ-DSC). The obtained experimental results suggest that the studied polymers represent the kinetic hydrate inhibition (KHI) performance. 0.5 wt% polyvinylcaprolactam (PVCap) solution shows the hydrate onset time of 34.4 min and subcooling temperature of 15.9 K, which is better KHI performance than that of pure water - hydrate onset time of 12.3 min and subcooling temperature of 6.0 K. 0.5 wt% polyvinylpyrrolidone (PVP) solution shows the hydrate onset time of 27.6 min and the subcooling temperature of 13.2 K while polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA) solution shows less KHI performance than PVP solution at both 0.5 and 5.0 wt%. However, PAM-co-AA solution shows slow growth rate and low hydrate amount than PVCap. In addition to hydrate onset and growth condition, torque change with time was investigated as one of KHI evaluation methods. 0.5 wt% PVCap solution shows the lowest average torque of 6.4 N cm and 0.5 wt% PAM-co-AA solution shows the average torque of 7.2 N cm. For 0.5 wt% PVP solution, it increases 11.5 N cm and 5.0 wt% PAM-co-AA solution shows the maximum average torque of 13.4 N cm, which is similar to the average torque of pure water, 15.2 N cm. Judging from the experimental results obtained by both an autoclave and a HP µ-DSC, the PVCap solution shows the best performance among the KHIs in terms of delaying hydrate nucleation. From these results, it can be concluded that the torque change with time is useful to identify the flow ability of tested solution, and the further research on the inhibition of hydrate formation can be approached in various aspects using a HP µ-DSC.

  19. Towards Scalable Strain Gauge-Based Joint Torque Sensors

    Science.gov (United States)

    D’Imperio, Mariapaola; Cannella, Ferdinando; Caldwell, Darwin G.; Cuschieri, Alfred

    2017-01-01

    During recent decades, strain gauge-based joint torque sensors have been commonly used to provide high-fidelity torque measurements in robotics. Although measurement of joint torque/force is often required in engineering research and development, the gluing and wiring of strain gauges used as torque sensors pose difficulties during integration within the restricted space available in small joints. The problem is compounded by the need for a scalable geometric design to measure joint torque. In this communication, we describe a novel design of a strain gauge-based mono-axial torque sensor referred to as square-cut torque sensor (SCTS), the significant features of which are high degree of linearity, symmetry, and high scalability in terms of both size and measuring range. Most importantly, SCTS provides easy access for gluing and wiring of the strain gauges on sensor surface despite the limited available space. We demonstrated that the SCTS was better in terms of symmetry (clockwise and counterclockwise rotation) and more linear. These capabilities have been shown through finite element modeling (ANSYS) confirmed by observed data obtained by load testing experiments. The high performance of SCTS was confirmed by studies involving changes in size, material and/or wings width and thickness. Finally, we demonstrated that the SCTS can be successfully implementation inside the hip joints of miniaturized hydraulically actuated quadruped robot-MiniHyQ. This communication is based on work presented at the 18th International Conference on Climbing and Walking Robots (CLAWAR). PMID:28820446

  20. Current-induced torques and interfacial spin-orbit coupling

    KAUST Repository

    Haney, Paul M.

    2013-12-19

    In bilayer systems consisting of an ultrathin ferromagnetic layer adjacent to a metal with strong spin-orbit coupling, an applied in-plane current induces torques on the magnetization. The torques that arise from spin-orbit coupling are of particular interest. Here we use first-principles methods to calculate the current-induced torque in a Pt-Co bilayer to help determine the underlying mechanism. We focus exclusively on the analog to the Rashba torque, and do not consider the spin Hall effect. The details of the torque depend strongly on the layer thicknesses and the interface structure, providing an explanation for the wide variation in results found by different groups. The torque depends on the magnetization direction in a way similar to that found for a simple Rashba model. Artificially turning off the exchange spin splitting and separately the spin-orbit coupling potential in the Pt shows that the primary source of the “fieldlike” torque is a proximate spin-orbit effect on the Co layer induced by the strong spin-orbit coupling in the Pt.

  1. Reducing torque ripples in permanent magnet synchronous motor

    Directory of Open Access Journals (Sweden)

    Rihab Abdelmoula

    2017-09-01

    Full Text Available Permanent magnet synchronous motors (PMSMs are exceptionally promising thanks to their many advantages compared with other types of electrical machines. Indeed, PMSMs are characterized by their important torque density, light weight, high air gap flux density, high acceleration, high efficiency and strong power-to-weight ratio. A surface-mounted PMSM (SPMSM is used in this work. The SPMSM is built using a 2D finite element method (FEM. Cogging torque, torque ripples and back-EMF are examined during the design process in order to obtain sinusoidal back-EMF and to minimise torque ripples which are one of the major problems with PMSMs. Two procedures are used to reduce the cogging torque of SPMSM: the effect of slot opening and the influence of skewing the stator laminations. Cogging torque factor tc and the torque ripples factor tr have been calculated to compare the two configurations (open slots and closed slots. Then, the configuration with closed slots is utilised with skewing the stator laminations for different angle 0°, 10° and 15°.

  2. Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive

    Science.gov (United States)

    Hernandez, Alan; Hess, Daniel P.

    2016-01-01

    This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48-hour cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for the all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.

  3. Standard practice for torque calibration of testing machines and devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice covers procedures and requirements for the calibration of torque for static and quasi-static torque capable testing machines or devices. These may, or may not, have torque indicating systems and include those devices used for the calibration of hand torque tools. Testing machines may be calibrated by one of the three following methods or combination thereof: 1.1.1 Use of standard weights and lever arms. 1.1.2 Use of elastic torque measuring devices. 1.1.3 Use of elastic force measuring devices and lever arms. 1.1.4 Any of the methods require a specific uncertainty of measurement and a traceability derived from national standards of mass and length. 1.2 The procedures of 1.1.1, 1.1.2, and 1.1.3 apply to the calibration of the torque-indicating systems associated with the testing machine, such as a scale, dial, marked or unmarked recorder chart, digital display, etc. In all cases the buyer/owner/user must designate the torque-indicating system(s) to be calibrated and included in the repor...

  4. Electrode position markedly affects knee torque in tetanic, stimulated contractions.

    Science.gov (United States)

    Vieira, Taian M; Potenza, Paolo; Gastaldi, Laura; Botter, Alberto

    2016-02-01

    The purpose of this study was to investigate how much the distance between stimulation electrodes affects the knee extension torque in tetanic, electrically elicited contractions. Current pulses of progressively larger amplitude, from 0 mA to maximally tolerated intensities, were delivered at 20 pps to the vastus medialis, rectus femoris and vastus lateralis muscles of ten, healthy male subjects. Four inter-electrode distances were tested: 32.5% (L1), 45.0% (L2), 57.5% (L3) and 70% (L4) of the distance between the patella apex and the anterior superior iliac spine. The maximal knee extension torque and the current leading to the maximal torque were measured and compared between electrode configurations. The maximal current tolerated by each participant ranged from 60 to 100 mA and did not depend on the inter-electrode distance. The maximal knee extension torque elicited did not differ between L3 and L4 (P = 0.15) but, for both conditions, knee torque was significantly greater than for L1 and L2 (P torque elicited for L3 and L4 was two to three times greater than that obtained for L1 and L2. The current leading to maximal torque was not as sensitive to inter-electrode distance. Except for L1 current intensity did not change with electrode configuration (P > 0.16). Key results presented here revealed that for a given stimulation intensity, knee extension torque increased dramatically with the distance between electrodes. The distance between electrodes seems therefore to critically affect knee torque, with potential implication for optimising exercise protocols based on electrical stimulation.

  5. High torque DC motor fabrication and test program

    Science.gov (United States)

    Makus, P.

    1976-01-01

    The testing of a standard iron and standard alnico permanent magnet two-phase, brushless dc spin motor for potential application to the space telescope has been concluded. The purpose of this study was to determine spin motor power losses, magnetic drag, efficiency and torque speed characteristics of a high torque dc motor. The motor was designed and built to fit an existing reaction wheel as a test vehicle and to use existing brass-board commutation and torque command electronics. The results of the tests are included in this report.

  6. A flight simulator control system using electric torque motors

    Science.gov (United States)

    Musick, R. O.; Wagner, C. A.

    1975-01-01

    Control systems are required in flight simulators to provide representative stick and rudder pedal characteristics. A system has been developed that uses electric dc torque motors instead of the more common hydraulic actuators. The torque motor system overcomes certain disadvantages of hydraulic systems, such as high cost, high power consumption, noise, oil leaks, and safety problems. A description of the torque motor system is presented, including both electrical and mechanical design as well as performance characteristics. The system develops forces sufficiently high for most simulations, and is physically small and light enough to be used in most motion-base cockpits.

  7. Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices

    KAUST Repository

    Akosa, Collins Ashu

    2017-03-01

    We propose that topological spin currents flowing in topologically nontrivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic nonadiabatic torque of the form Tt∼[(∂xm×∂ym)·m]∂ym. We show that this torque, which is absent in one-dimensional domain walls and/or nontopological textures, is responsible for the enhanced nonadiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.

  8. Torque Modeling and Control of a Variable Compression Engine

    OpenAIRE

    Bergström, Andreas

    2003-01-01

    The SAAB variable compression engine is a new engine concept that enables the fuel consumption to be radically cut by varying the compression ratio. A challenge with this new engine concept is that the compression ratio has a direct influence on the output torque, which means that a change in compression ratio also leads to a change in the torque. A torque change may be felt as a jerk in the movement of the car, and this is an undesirable effect since the driver has no control over the compre...

  9. Torque converter transient characteristics prediction using computational fluid dynamics

    International Nuclear Information System (INIS)

    Yamaguchi, T; Tanaka, K

    2012-01-01

    The objective of this research is to investigate the transient torque converter performance used in an automobile. A new technique in computational fluid dynamics is introduced, which includes the inertia of the turbine in a three dimensional simulation of the torque converter during a launch condition. The simulation results are compared to experimental test data with good agreement across the range of data. In addition, the simulated flow structure inside the torque converter is visualized and compared to results from a steady-state calculation.

  10. Spin transfer torque with spin diffusion in magnetic tunnel junctions

    KAUST Repository

    Manchon, Aurelien

    2012-08-09

    Spin transport in magnetic tunnel junctions in the presence of spin diffusion is considered theoretically. Combining ballistic tunneling across the barrier and diffusive transport in the electrodes, we solve the spin dynamics equation in the metallic layers. We show that spin diffusion mixes the transverse spin current components and dramatically modifies the bias dependence of the effective spin transfer torque. This leads to a significant linear bias dependence of the out-of-plane torque, as well as a nonconventional thickness dependence of both spin torque components.

  11. Computational Fluid Dynamics in Torque Converters: Validation and Application

    OpenAIRE

    Schweitzer, Jean; Gandham, Jeya

    2003-01-01

    This article describes some of the computational fluid dynamics (CFD) work being done on three-element torque converters using a commercially available package CFX TASCflow. The article details some of the work done to validate CFD results and gives examples of ways in which CFD is used in the torque-converter design process. Based on the validation study, it is shown that CFD can be used as a design and analysis tool to make decisions about design direction. Use of CFD in torque converters i...

  12. Experimental investigation of torque scaling and coherent structures in turbulent Taylor–Couette flow

    International Nuclear Information System (INIS)

    Tokgoz, S; Elsinga, G E; Delfos, R; Westerweel, J

    2011-01-01

    The effect of flow structures to the torque values of fully turbulent Taylor-Couette flow was experimentally studied using tomographic PIV. The measurements were performed for various relative cylinder rotation speeds and Reynolds numbers, based on a study of Ravelet et al. (2010). We confirmed that the flow structures are strongly influenced by the rotation number. Our analyses using time-averaged mean flow showed the presence of Taylor vortices for the two smallest rotation numbers that were studied. Increasing the rotation number initially resulted in the shape deformation of the Taylor vortices. Further increment towards only outer cylinder rotation, showed transition to the dominance of the small scale vortices and absence of Taylor vortex-like structures. We compared the transition of the flow structures with the curves of dimensionless torque. Sudden changes of the flow structures confirmed the presence of transition points on the torque curve, where the dominance of small and large scale vortical structures on the mean flow interchanges.

  13. An Ultra-Low Power Wireless Sensor Network for Bicycle Torque Performance Measurements

    Directory of Open Access Journals (Sweden)

    Sadik K. Gharghan

    2015-05-01

    Full Text Available In this paper, we propose an energy-efficient transmission technique known as the sleep/wake algorithm for a bicycle torque sensor node. This paper aims to highlight the trade-off between energy efficiency and the communication range between the cyclist and coach. Two experiments were conducted. The first experiment utilised the Zigbee protocol (XBee S2, and the second experiment used the Advanced and Adaptive Network Technology (ANT protocol based on the Nordic nRF24L01 radio transceiver chip. The current consumption of ANT was measured, simulated and compared with a torque sensor node that uses the XBee S2 protocol. In addition, an analytical model was derived to correlate the sensor node average current consumption with a crank arm cadence. The sensor node achieved 98% power savings for ANT relative to ZigBee when they were compared alone, and the power savings amounted to 30% when all components of the sensor node are considered. The achievable communication range was 65 and 50 m for ZigBee and ANT, respectively, during measurement on an outdoor cycling track (i.e., velodrome. The conclusions indicate that the ANT protocol is more suitable for use in a torque sensor node when power consumption is a crucial demand, whereas the ZigBee protocol is more convenient in ensuring data communication between cyclist and coach.

  14. An ultra-low power wireless sensor network for bicycle torque performance measurements.

    Science.gov (United States)

    Gharghan, Sadik K; Nordin, Rosdiadee; Ismail, Mahamod

    2015-05-21

    In this paper, we propose an energy-efficient transmission technique known as the sleep/wake algorithm for a bicycle torque sensor node. This paper aims to highlight the trade-off between energy efficiency and the communication range between the cyclist and coach. Two experiments were conducted. The first experiment utilised the Zigbee protocol (XBee S2), and the second experiment used the Advanced and Adaptive Network Technology (ANT) protocol based on the Nordic nRF24L01 radio transceiver chip. The current consumption of ANT was measured, simulated and compared with a torque sensor node that uses the XBee S2 protocol. In addition, an analytical model was derived to correlate the sensor node average current consumption with a crank arm cadence. The sensor node achieved 98% power savings for ANT relative to ZigBee when they were compared alone, and the power savings amounted to 30% when all components of the sensor node are considered. The achievable communication range was 65 and 50 m for ZigBee and ANT, respectively, during measurement on an outdoor cycling track (i.e., velodrome). The conclusions indicate that the ANT protocol is more suitable for use in a torque sensor node when power consumption is a crucial demand, whereas the ZigBee protocol is more convenient in ensuring data communication between cyclist and coach.

  15. PREFACE: The Science of Making Torque from Wind 2014 (TORQUE 2014)

    Science.gov (United States)

    Mann, Jakob; Bak, Christian; Bechmann, Andreas; Bingöl, Ferhat; Dellwik, Ebba; Dimitrov, Nikolay; Giebel, Gregor; Hansen, Martin O. L.; Jensen, Dorte Juul; Larsen, Gunner; Aagaard Madsen, Helge; Natarajan, Anand; Rathmann, Ole; Sathe, Ameya; Nørkær Sørensen, Jens; Nørkær Sørensen, Niels

    2014-06-01

    The 186 papers in this volume constitute the proceedings of the fifth Science of Making Torque from Wind conference, which is organized by the European Academy of Wind Energy (EAWE, www.eawe.eu). The conference, also called Torque 2014, is held at the Technical University of Denmark (DTU) 17-20 June 2014. The EAWE conference series started in 2004 in Delft, the Netherlands. In 2007 it was held in Copenhagen, in 2010 in Heraklion, Greece, and then in 2012 in Oldenburg, Germany. The global yearly production of electrical energy by wind turbines has grown approximately by 25% annually over the last couple of decades and covers now 2-3% of the global electrical power consumption. In order to make a significant impact on one of the large challenges of our time, namely global warming, the growth has to continue for a decade or two yet. This in turn requires research and education in wind turbine aerodynamics and wind resources, the two topics which are the main subjects of this conference. Similar to the growth in electrical power production by wind is the growth in scientific papers about wind energy. Over the last decade the number of papers has also grown by about 25% annually, and many research based companies all over the world are founded. Hence, the wind energy research community is rapidly expanding and the Torque conference series offers a good opportunity to meet and exchange ideas. We hope that the Torque 2014 will heighten the quality of the wind energy research, while the participants will enjoy each others company in Copenhagen. Many people have been involved in producing the Torque 2014 proceedings. The work by more than two hundred reviewers ensuring the quality of the papers is greatly appreciated. The timely evaluation and coordination of the reviews would not have been possible without the work of sixteen ''section editors'' all from DTU Wind Energy: Christian Bak, Andreas Bechmann, Ferhat Bingöl, Ebba Dellwik, Nikolay Dimitrov, Gregor Giebel, Martin

  16. Relationship between Muscle Torque and Performance in Special and Specific Exercises in Young Weightlifters

    Directory of Open Access Journals (Sweden)

    Szyszka Paulina

    2016-09-01

    Full Text Available Introduction. The aim of the current study was to examine the relationship between knee and elbow isometric muscle torque values and the results obtained in special and specific exercises in young weightlifters. Material and methods. The study involved eight young weightlifters (age: 19.9 ± 4.3 years; height: 176.8 ± 10.6 cm; weight: 69.0 ± 19.7 kg - pretest, 70.9 ± 21.6 - posttest. Their performance put them in the second and third top classes of weightlifters their age according to the Polish norms for weightlifting (the so-called ‘national class’ and ‘first class’ in the Polish system, which are lower than the ‘international class’. The differences between the values obtained in the first measurement of torque performed at the beginning of the preparation period and those obtained at the beginning of the immediate pre-competition period were compared with the differences in the maximal load lifted in special and specific exercises. Results. The training that the weightlifters underwent during the preparation period caused a significant increase in the relative torque values of the knee extensors (0.56 Nm/kg on average, p ≤ 0.047 and those of the elbow flexors (0.35 Nm/kg, p ≤ 0.0002. Significant differences (p ≤ 0.05 were observed between the results obtained in all of the special and specific exercises examined. A statistically significant relationship was also found between the changes in relative torque values and the results achieved in special and specific exercises. Conclusions. The regression equations derived in the study can help predict sports performance outcomes based on the results of laboratory tests.

  17. Muscle Twitch Torque During Two Different in Volume Isometric Exercise Protocols: Fatigue Effects on Postactivation Potentiation.

    Science.gov (United States)

    Xenofondos, Anthi; Bassa, Eleni; Vrabas, Ioannis S; Kotzamanidis, Christos; Patikas, Dimitrios A

    2018-02-01

    Xenofondos, A, Bassa, E, Vrabas, IS, Kotzamanidis, C, and Patikas, D. Muscle twitch torque during two different in volume isometric exercise protocols: fatigue effects on postactivation potentiation. J Strength Cond Res 32(2): 578-586, 2018-The purpose of this study was to quantify the effect of the contraction duration of 2 isometric exercise protocols on the postactivation potentiation of 14 well-trained men (age: 22.6 ± 2.8 years, height: 180.3 ± 5.9 cm, and body mass: 72.3 ± 37.9 kg). The protocols consisted of 4 × 6 maximal plantar flexions, of 3-second (P3) or 6-second (P6) duration, performed in random order, with a 2-minute and 15-second intervals between the sets and repetitions, respectively. The torque during maximal isometric voluntary contraction (MIVC), the peak twitch torque (TT), and the rate of torque development (RTD) after each MIVC were analyzed for the first and the last trial of each set, the average of all trials of each set, and the trials within each set that had the highest peak TT. The MIVC had an overall greater reduction during P6 compared with P3 (P3: -4.6 ± 2.3 vs. P6: -16.0 ± 1.9%). P6 showed higher potentiation in TT during the initial repetitions of the first 2 sets (p twitch RTD presented no systematic difference between the 2 protocols (p > 0.05). These data demonstrate the dependence of the TT potentiation on the conditioning stimulus and verify the cumulative effect of potentiation, suggesting the implementation of longer contractions to achieve maximal but temporal TT potentiation and shorter contractions for less variable but prolonged potentiation.

  18. An improved torque density Modulated Pole Machine for low speed high torque applications

    DEFF Research Database (Denmark)

    Washington, J. G.; Atkinson, G. J.; Baker, N. J.

    2012-01-01

    This paper presents a new topology for three-phase Modulated Pole Machines. This new topology the “Combined Phase Modulated Pole Machine” is analysed and compared to the more traditional technology of three separate single phase units stacked axially with a separation between phases. Three......- dimensional Finite Element calculations are used to compare performance of the machines under the same conditions, it is shown that the new Combined Phase topology produces a greater torque whilst reducing the number of components required to assemble the machine and increasing its mechanical integrity....

  19. Torque Control of Friction Stir Welding, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Longhurst Engineering, PLC and Vanderbilt University propose the innovation of torque control of friction stir welding (FSW) as a replacement to force control of...

  20. High Torque, Direct Drive Electric Motor, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Bear Engineering proposes to advance the development of an innovative high torque, low speed, direct drive motor in order to meet NASA's requirements for such...

  1. New Cogging Torque Reduction Methods for Permanent Magnet Machine

    Science.gov (United States)

    Bahrim, F. S.; Sulaiman, E.; Kumar, R.; Jusoh, L. I.

    2017-08-01

    Permanent magnet type motors (PMs) especially permanent magnet synchronous motor (PMSM) are expanding its limbs in industrial application system and widely used in various applications. The key features of this machine include high power and torque density, extending speed range, high efficiency, better dynamic performance and good flux-weakening capability. Nevertheless, high in cogging torque, which may cause noise and vibration, is one of the threat of the machine performance. Therefore, with the aid of 3-D finite element analysis (FEA) and simulation using JMAG Designer, this paper proposed new method for cogging torque reduction. Based on the simulation, methods of combining the skewing with radial pole pairing method and skewing with axial pole pairing method reduces the cogging torque effect up to 71.86% and 65.69% simultaneously.

  2. High Torque, Direct Drive Electric Motor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Bear Engineering proposes to develop an innovative high torque, low speed, direct drive motor in order to meet NASA's requirements for such devices. Fundamentally,...

  3. Effects of cavitation on performance of automotive torque converter

    Directory of Open Access Journals (Sweden)

    Jaewon Ju

    2016-06-01

    Full Text Available Cavitation is a phenomenon whereby vapor bubbles of a flowing liquid are formed in a local region where the pressure of the liquid is below its vapor pressure. It is well known that cavitation in torque converters occurs frequently when a car with an automatic transmission makes an abrupt start. Cavitation is closely related to a performance drop and noise generation at a specific operating condition in a car and a torque converter itself. This study addressed the relation between cavitation and performance in an automotive torque converter in a quantitative and qualitative manner using numerical simulations. The cavitation was calculated at various operating conditions using a commercial flow solver with the homogeneous cavitation model, and the torque converter performance was compared with the experimental data. Numerical results well match to the data and indicate that the cavitation causes significant performance drop, as the pump speed increases or both speed ratio and reference pressure decrease.

  4. Manipulating the voltage dependence of tunneling spin torques

    KAUST Repository

    Manchon, Aurelien

    2012-10-01

    Voltage-driven spin transfer torques in magnetic tunnel junctions provide an outstanding tool to design advanced spin-based devices for memory and reprogrammable logic applications. The non-linear voltage dependence of the torque has a direct impact on current-driven magnetization dynamics and on devices performances. After a brief overview of the progress made to date in the theoretical description of the spin torque in tunnel junctions, I present different ways to alter and control the bias dependence of both components of the spin torque. Engineering the junction (barrier and electrodes) structural asymmetries or controlling the spin accumulation profile in the free layer offer promising tools to design effcient spin devices.

  5. Exoskeleton Power and Torque Requirements Based on Human Biomechanics

    National Research Council Canada - National Science Library

    Crowell, Harrison

    2002-01-01

    .... In providing design guidance, the authors had two goals. The first goal was to provide estimates of the angles, torques, and powers for the ankles, knees, and hips of an exoskeleton based on data collected from humans...

  6. Spin-Orbit Torques in Co/Pd Multilayer Nanowires

    KAUST Repository

    Jamali, Mahdi

    2013-12-09

    Current induced spin-orbit torques have been studied in ferromagnetic nanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic anisotropy. Using Hall voltage and lock-in measurements, it is found that upon injection of an electric current both in-plane (Slonczewski-like) and perpendicular (fieldlike) torques build up in the nanowire. The torque efficiencies are found to be as large as 1.17 and 5 kOe at 108  A/cm2 for the in-plane and perpendicular components, respectively, which is surprisingly comparable to previous studies in ultrathin (∼1  nm) magnetic bilayers. We show that this result cannot be explained solely by spin Hall effect induced torque at the outer interfaces, indicating a probable contribution of the bulk of the Co/Pd multilayer.

  7. Intraband and interband spin-orbit torques in noncentrosymmetric ferromagnets

    KAUST Repository

    Li, Hang

    2015-04-01

    Intraband and interband contributions to the current-driven spin-orbit torque in magnetic materials lacking inversion symmetry are theoretically studied using the Kubo formula. In addition to the current-driven fieldlike torque TFL=τFLm×uso (uso being a unit vector determined by the symmetry of the spin-orbit coupling), we explore the intrinsic contribution arising from impurity-independent interband transitions and producing an anti-damping-like torque of the form TDL=τDLm×(uso×m). Analytical expressions are obtained in the model case of a magnetic Rashba two-dimensional electron gas, while numerical calculations have been performed on a dilute magnetic semiconductor (Ga,Mn)As modeled by the Kohn-Luttinger Hamiltonian exchange coupled to the Mn moments. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described.

  8. Vector control structure of an asynchronous motor at maximum torque

    Science.gov (United States)

    Chioncel, C. P.; Tirian, G. O.; Gillich, N.; Raduca, E.

    2016-02-01

    Vector control methods offer the possibility to gain high performance, being widely used. Certain applications require an optimum control in limit operating conditions, as, at maximum torque, that is not always satisfied. The paper presents how the voltage and the frequency for an asynchronous machine (ASM) operating at variable speed are determinate, with an accent on the method that keeps the rotor flux constant. The simulation analyses consider three load types: variable torque and speed, variable torque and constant speed, constant torque and variable speed. The final values of frequency and voltage are obtained through the proposed control schemes with one controller using the simulation language based on the Maple module. The dynamic analysis of the system is done for the case with P and PI controller and allows conclusions on the proposed method, which can have different applications, as the ASM in wind turbines.

  9. Direct Torque Control With Feedback Linearization for Induction Motor Drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Jafarzadeh, Saeed; Fadali, Sami M.

    2017-01-01

    This paper describes a direct-torque-controlled (DTC) induction motor (IM) drive that employs feedback linearization and sliding-mode control (SMC). A new feedback linearization approach is proposed, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitu...... in simulations. The sliding controller is compared with a linear DTC scheme with and without feedback linearization. Extensive experimental results for a sensorless IM drive validate the proposed solution.......This paper describes a direct-torque-controlled (DTC) induction motor (IM) drive that employs feedback linearization and sliding-mode control (SMC). A new feedback linearization approach is proposed, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude...

  10. Heat Control via Torque Control in Friction Stir Welding

    Science.gov (United States)

    Venable, Richard; Colligan, Kevin; Knapp, Alan

    2004-01-01

    In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

  11. Simulation of Brushless DC Motor using Direct Torque Control

    OpenAIRE

    Mrs.G. Kusuma; S. Rukhsana Begum

    2014-01-01

    This paper deals with modelling of three phases brushless dc motor with MATLAB/SIMULINK software BLDC motor have advantages according to brushless dc motor and induction motor’s. They have improve speed torque charactistics, high efficiency high transient response and small size. It approaches for reducing the torque ripples of BLDC motor using DTC, by using control technique’s ,but present work mainly concentrate on advanced method. The whole drive system is simulated based o...

  12. Does the 'torque test' measure cerebral dominance in adults?

    Science.gov (United States)

    Demarest, J; Demarest, L

    1980-02-01

    The direction of drawing a circle, labeled the 'torque test' (Blau, 1977), was evaluated in 74 normal adults (age 14 to 44 yr.) as a predictor of both handedness and cerebral dominance on the dichotic listening test. The results indicate that torque is related to handedness but not to lateralization of language. We suggest that circle-drawing by adults is dependent more on the muscle mechanics of the hand than on cerebral dominance.

  13. KNEE ISOKINETIC TORQUE IMBALANCE IN FEMALE FUTSAL PLAYERS

    OpenAIRE

    Rodrigues, Ana Carolina de Mello Alves; Vieira, Nathália Arnosti; Marche, Ana Lorena; Santana, Juliana Exel; Vaz, Marco Aurélio; Cunha, Sergio Augusto

    2017-01-01

    ABSTRACT Introduction: The specificity of sports training can lead to muscle specialization with a possible change in the natural hamstring/quadriceps torque ratio (HQ ratio), constituting a risk factor for muscle injury at the joint angles in which muscle imbalance may impair dynamic stability. Objective: The aim was to evaluate the torque distribution of the hamstrings and quadriceps and the HQ ratio throughout the range of motion in order to identify possible muscle imbalances at the kne...

  14. Reflex and Non-Reflex Torque Responses to Stretch of the Human Knee Extensors

    National Research Council Canada - National Science Library

    Mrachacz-Kersting, N

    2001-01-01

    .... The quadriceps muscles were stretched at various background torques, produced either voluntarily or electrically and thus the purely reflex-mediated torque could be calculated. The contribution of the reflex mediated stiffness initially low, increased with increasing background torques for the range of torques investigated.

  15. Instantaneous flywheel torque of IC engine grey-box identification

    Science.gov (United States)

    Milašinović, A.; Knežević, D.; Milovanović, Z.; Škundrić, J.

    2018-01-01

    In this paper a mathematical model developed for the identification of excitation torque acting on the IC engine flywheel is presented. The excitation torque gained through internal combustion of the fuel in the IC engine is transmitted from the flywheel to the transmission. The torque is not constant but variable and is a function of the crank angle. The verification of the mathematical model was done on a 4-cylinder 4-stroke diesel engine for which the in-cylinder pressure was measured in one cylinder and the instantaneous angular speed of the crankshaft at its free end. The research was conducted on a hydraulic engine brake. Inertial forces of all rotational parts, from flywheel to the turbine wheel of the engine brake, are acting on the flywheel due to the nonuniform motion of the flywheel. It is known from the theory of turbomachinery that the torque on the hydraulic brake is a quadratic function of angular speed. Due to that and the variable angular speed of the turbine wheel of the engine brake, the torque during one engine cycle is also variable. The motivation for this research was the idea (intention) to determine the instantaneous torque acting on the flywheel as a function of the crank angle with a mathematical model without any measuring and based on this to determine the quality of work of specific cylinders of the multi-cylinder engine. The crankshaft was considered elastic and also its torsional vibrations were taken into account.

  16. Angular dependence of spin-orbit spin-transfer torques

    KAUST Repository

    Lee, Ki-Seung

    2015-04-06

    In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

  17. Input torque sensitivity to uncertain parameters in biped robot

    Science.gov (United States)

    Ding, Chang-Tao; Yang, Shi-Xi; Gan, Chun-Biao

    2013-06-01

    Input torque is themain power to maintain bipedal walking of robot, and can be calculated from trajectory planning and dynamic modeling on biped robot. During bipedal walking, the input torque is usually required to be adjusted due to some uncertain parameters arising from objective or subjective factors in the dynamical model to maintain the pre-planned stable trajectory. Here, a planar 5-link biped robot is used as an illustrating example to investigate the effects of uncertain parameters on the input torques. Kinematic equations of the biped robot are firstly established by the third-order spline curves based on the trajectory planning method, and the dynamic modeling is accomplished by taking both the certain and uncertain parameters into account. Next, several evaluation indices on input torques are introduced to perform sensitivity analysis of the input torque with respect to the uncertain parameters. Finally, based on the Monte Carlo simulation, the values of evaluation indices on input torques are presented, from which all the robot parameters are classified into three categories, i.e., strongly sensitive, sensitive and almost insensitive parameters.

  18. Nonlocal Gilbert damping tensor within the torque-torque correlation model

    Science.gov (United States)

    Thonig, Danny; Kvashnin, Yaroslav; Eriksson, Olle; Pereiro, Manuel

    2018-01-01

    An essential property of magnetic devices is the relaxation rate in magnetic switching, which depends strongly on the damping in the magnetization dynamics. It was recently measured that damping depends on the magnetic texture and, consequently, is a nonlocal quantity. The damping enters the Landau-Lifshitz-Gilbert equation as the phenomenological Gilbert damping parameter α , which does not, in a straightforward formulation, account for nonlocality. Efforts were spent recently to obtain Gilbert damping from first principles for magnons of wave vector q . However, to the best of our knowledge, there is no report about real-space nonlocal Gilbert damping αi j. Here, a torque-torque correlation model based on a tight-binding approach is applied to the bulk elemental itinerant magnets and it predicts significant off-site Gilbert damping contributions, which could be also negative. Supported by atomistic magnetization dynamics simulations, we reveal the importance of the nonlocal Gilbert damping in atomistic magnetization dynamics. This study gives a deeper understanding of the dynamics of the magnetic moments and dissipation processes in real magnetic materials. Ways of manipulating nonlocal damping are explored, either by temperature, materials doping, or strain.

  19. Lagrangian averaging with geodesic mean

    Science.gov (United States)

    Oliver, Marcel

    2017-11-01

    This paper revisits the derivation of the Lagrangian averaged Euler (LAE), or Euler-α equations in the light of an intrinsic definition of the averaged flow map as the geodesic mean on the volume-preserving diffeomorphism group. Under the additional assumption that first-order fluctuations are statistically isotropic and transported by the mean flow as a vector field, averaging of the kinetic energy Lagrangian of an ideal fluid yields the LAE Lagrangian. The derivation presented here assumes a Euclidean spatial domain without boundaries.

  20. Loss of knee extensor torque complexity during fatiguing isometric muscle contractions occurs exclusively above the critical torque.

    Science.gov (United States)

    Pethick, Jamie; Winter, Samantha L; Burnley, Mark

    2016-06-01

    The complexity of knee extensor torque time series decreases during fatiguing isometric muscle contractions. We hypothesized that because of peripheral fatigue, this loss of torque complexity would occur exclusively during contractions above the critical torque (CT). Nine healthy participants performed isometric knee extension exercise (6 s of contraction, 4 s of rest) on six occasions for 30 min or to task failure, whichever occurred sooner. Four trials were performed above CT (trials S1-S4, S1 being the lowest intensity), and two were performed below CT (at 50% and 90% of CT). Global, central, and peripheral fatigue were quantified using maximal voluntary contractions (MVCs) with femoral nerve stimulation. The complexity of torque output was determined using approximate entropy (ApEn) and the detrended fluctuation analysis-α scaling exponent (DFA-α). The MVC torque was reduced in trials below CT [by 19 ± 4% (means ± SE) in 90%CT], but complexity did not decrease [ApEn for 90%CT: from 0.82 ± 0.03 to 0.75 ± 0.06, 95% paired-samples confidence intervals (CIs), 95% CI = -0.23, 0.10; DFA-α from 1.36 ± 0.01 to 1.32 ± 0.03, 95% CI -0.12, 0.04]. Above CT, substantial reductions in MVC torque occurred (of 49 ± 8% in S1), and torque complexity was reduced (ApEn for S1: from 0.67 ± 0.06 to 0.14 ± 0.01, 95% CI = -0.72, -0.33; DFA-α from 1.38 ± 0.03 to 1.58 ± 0.01, 95% CI 0.12, 0.29). Thus, in these experiments, the fatigue-induced loss of torque complexity occurred exclusively during contractions performed above the CT. Copyright © 2016 the American Physiological Society.

  1. Convergence of multiple ergodic averages

    OpenAIRE

    Host, Bernard

    2006-01-01

    These notes are based on a course for a general audience given at the Centro de Modeliamento Matem\\'atico of the University of Chile, in December 2004. We study the mean convergence of multiple ergodic averages, that is, averages of a product of functions taken at different times. We also describe the relations between this area of ergodic theory and some classical and some recent results in additive number theory.

  2. Application of Space Vector Modulation in Direct Torque Control of PMSM

    Directory of Open Access Journals (Sweden)

    Michal Malek

    2008-01-01

    Full Text Available The paper deals with an improvement of direct torque control method for permanent magnet synchronous motor drives. Electrical torque distortion of the machine under original direct torque control is relatively high and if proper measures are taken it can be substantially decreased. The proposed solution here is to combine direct torque control with the space vector modulation technique. Such approach can eliminate torque distortion while preserving the simplicity of the original method.

  3. Advanced single tooth torquing plier with high precision: A clinical innovation

    Directory of Open Access Journals (Sweden)

    Jitendra Raghuwanshi

    2017-01-01

    Full Text Available Torque is the force which gives the operator control over the movements of roots of teeth in bilateral direction. There are various pliers available to apply torque in individual tooth, but none of the pliers are capable of measuring accurately the degrees of torque incorporated, so we have attempted to make a modified torquing plier to incorporate and measure the degrees of incorporated torque precisely.

  4. TRAINING-INDUCED CHANGES IN THE TOPOGRAPHY OF MUSCLE TORQUES AND MAXIMAL MUSCLE TORQUES IN BASKETBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Krzysztof Buśko

    2012-01-01

    Full Text Available The aim of the study was to detect changes in the maximal muscle torques in male basketball players during a two-year training cycle. We verified the hypothesis that different workloads applied during the preparation and competition periods would result in changes in the maximal muscle torques of the athletes (increase during the former and decrease or no change during the latter period accompanied by no alteration of the percent muscle topography of all the muscle groups tested. The examinations were conducted on nine senior male basketball players from the Polish national team. Estimations of the muscle torques in static conditions were performed at the end of the preparation (measurements I and III and competition (measurements II and IV periods of a two-year training cycle. Eleven muscle groups were studied including flexors and extensors of the trunk and flexors and extensors of the shoulder, the elbow, the hip, the knee, and the ankle. Muscle torques of the shoulder and the elbow insignificantly decreased except for the muscle torque of the flexors of the shoulder. Muscle torques of the flexors and extensors of the trunk as well as of the flexors and extensors of the hip, the knee, and the ankle increased between measurements I and III and between measurements I and IV with the only exception being the muscle torque of the flexors of the knee (which significantly decreased by 7.4% In the case of the flexors and extensors of the trunk and the flexors and extensors of the hip, the changes appeared to be significant. The sum of the muscle torques of the upper limbs markedly decreased between the preparation (measurement I and competition (measurement IV periods. The sum of the muscle torques of the trunk and the lower limbs and the sum of the muscle torques of the eleven muscle groups significantly increased between measurements I and IV. Percent muscle topography significantly decreased for the flexors and extensors of the shoulder and the

  5. Ergodic averages via dominating processes

    DEFF Research Database (Denmark)

    Møller, Jesper; Mengersen, Kerrie

    2006-01-01

    We show how the mean of a monotone function (defined on a state space equipped with a partial ordering) can be estimated, using ergodic averages calculated from upper and lower dominating processes of a stationary irreducible Markov chain. In particular, we do not need to simulate the stationary...... Markov chain and we eliminate the problem of whether an appropriate burn-in is determined or not. Moreover, when a central limit theorem applies, we show how confidence intervals for the mean can be estimated by bounding the asymptotic variance of the ergodic average based on the equilibrium chain....

  6. A New Approach of Minimizing Commutation Torque Ripple for BLDCM

    Directory of Open Access Journals (Sweden)

    Bo Tan

    2017-10-01

    Full Text Available The properties of brushless DC motor (BLDCM are similar to the fractional, slot-concentrated winding of permanent-magnet synchronous machines, and they fit well for electric vehicle application. However, BLDCM still suffers from the high commutation torque ripple in the case of the traditional square-wave current control (SWC method, where the current vector rotates asynchronously with back-EMF. A current optimizing control (COC method for BLDCM is proposed in the paper to minimize the commutation torque ripple. The trajectories of the three phase currents are planned by the given torque and the optimized result of the copper loss and motor torque equations. The properties of COC are analyzed and compared with that of SWC in the stationary reference frame. The results show that the way of making the current vector rotate synchronously with back-EMF (back-Electromotive Force can minimize the modulus and velocity of the current vector in the commutation region, and reduce the torque ripple. Experimental tests obtained from an 82 W BLDCM are done to confirm the theoretical findings.

  7. Direct Torque Control of Induction Motor with Matrix Converter

    Directory of Open Access Journals (Sweden)

    Khalaf Salloum Gaeid

    2016-05-01

    Full Text Available The matrix converter (MC with direct torque control (DTC combination is efficient way to get better performance specifications in the industry. The MC and the DTC advantages are combined together. The reduction of complexity and cost of DC link in the DTC since it has no capacitors in the circuit. However, the controlling torque is a big problem it in DTC because of high ripple torque production which results in vibrations response in the operation of the iductuction motor as it has no PID to control the torque directly. To overcome this, a combination of MC with DTC is applied to reduce the fluctuation in the output torque and minimize the steady state error. This paper presents the simulation analysis of induction machine drives using Maltlab/Simulink toolbox R2012a. Design of DTC induction motor drive, MC with constant switching frequency, speed controller and stability investigation as well as controllability and observabilty with minimum final prediction (FPE steady state error and loss functionality has been carried out precisely.

  8. Cogging Torque Reduction Techniques for Spoke-type IPMSM

    Science.gov (United States)

    Bahrim, F. S.; Sulaiman, E.; Kumar, R.; Jusoh, L. I.

    2017-08-01

    A spoke-type interior permanent magnet synchronous motor (IPMSM) is extending its tentacles in industrial arena due to good flux-weakening capability and high power density. In many of the application, high strength of permanent magnet causes the undesirable effects of high cogging torque that can aggravate performance of the motor. High cogging torque is significantly produced by IPMSM due to the similar length and the effectiveness of the magnetic air-gap. The address of this study is to analyze and compare the cogging torque effect and performance of four common techniques for cogging torque reduction such as skewing, notching, pole pairing and rotor pole pairing. With the aid of 3-D finite element analysis (FEA) by JMAG software, a 6S-4P Spoke-type IPMSM with various rotor-PM configurations has been designed. As a result, the cogging torque effect reduced up to 69.5% for skewing technique, followed by 31.96%, 29.6%, and 17.53% by pole pairing, axial pole pairing and notching techniques respectively.

  9. Spin-transfer torque in spin filter tunnel junctions

    KAUST Repository

    Ortiz Pauyac, Christian

    2014-12-08

    Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green\\'s function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

  10. Rotational and peak torque stiffness of rugby shoes.

    Science.gov (United States)

    Ballal, Moez S; Usuelli, Federico Giuseppe; Montrasio, Umberto Alfieri; Molloy, Andy; La Barbera, Luigi; Villa, Tomaso; Banfi, Giuseppe

    2014-09-01

    Sports people always strive to avoid injury. Sports shoe designs in many sports have been shown to affect traction and injury rates. The aim of this study is to demonstrate the differing stiffness and torque in rugby boots that are designed for the same effect. Five different types of rugby shoes commonly worn by scrum forwards were laboratory tested for rotational stiffness and peak torque on a natural playing surface generating force patterns that would be consistent with a rugby scrum. The overall internal rotation peak torque was 57.75±6.26 Nm while that of external rotation was 56.55±4.36 Nm. The Peak internal and external rotational stiffness were 0.696±0.1 and 0.708±0.06 Nm/deg respectively. Our results, when compared to rotational stiffness and peak torques of football shoes published in the literature, show that shoes worn by rugby players exert higher rotational and peak torque stiffness compared to football shoes when tested on the same natural surfaces. There was significant difference between the tested rugby shoes brands. In our opinion, to maximize potential performance and lower the potential of non-contact injury, care should be taken in choosing boots with stiffness appropriate to the players main playing role. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Torque values of antagonistic muscles of the hipjoint. Pilot study.

    Science.gov (United States)

    Derewiecki, Tomasz; Duda, Marta; Majcher, Piotr; Mroczek, Krzysztof

    2012-01-01

    The hip joint is a multiaxial articulation and the most mobile joint of the lower extremity. It can be subject to overloading by the repetition of a motor pattern produced by imbalanced muscle groups. To determine mean torque values of the external forces acting on the hip joint in various age groups; to compare the relations between the torque values of antagonistic hip muscles; to correlate changes in mean torque values of the hip muscles with age. The study involved a group of 120 women aged 19-85 years divided into 6 age groups of 20 subjects each. The presence of knee or hip pathology was an exclusion criterion. The tests were carried out in the Zamość Rehabilitation Department of CMPA in an SPB2-FM unit. The highest mean torque values for all muscle groups were seen in women aged 19-25 years. The values gradually decreased with age. 1. The SPB2-FM unit is an objective tool for evaluating torques of the hip muscles and makes it possible to monitor changes occurring in the process of rehabilitation, as well as to diagnose risks resulting from a decrease in hip muscle strength. 2. The present study of healthy subjects provides baseline data for further comparisons with patients suffering from hip pathology and preliminary input for determining reference values of pelvic girdle muscle strength.

  12. Torques Induced by Scattered Pebble-flow in Protoplanetary Disks

    Science.gov (United States)

    Benítez-Llambay, Pablo; Pessah, Martin E.

    2018-03-01

    Fast inward migration of planetary cores is a common problem in the current planet formation paradigm. Even though dust is ubiquitous in protoplanetary disks, its dynamical role in the migration history of planetary embryos has not been assessed. In this Letter, we show that the scattered pebble-flow induced by a low-mass planetary embryo leads to an asymmetric dust-density distribution that is able to exert a net torque. By analyzing a large suite of multifluid hydrodynamical simulations addressing the interaction between the disk and a low-mass planet on a fixed circular orbit, and neglecting dust feedback onto the gas, we identify two different regimes, gas- and gravity-dominated, where the scattered pebble-flow results in almost all cases in positive torques. We collect our measurements in a first torque map for dusty disks, which will enable the incorporation of the effect of dust dynamics on migration into population synthesis models. Depending on the dust drift speed, the dust-to-gas mass ratio/distribution, and the embryo mass, the dust-induced torque has the potential to halt inward migration or even induce fast outward migration of planetary cores. We thus anticipate that dust-driven migration could play a dominant role during the formation history of planets. Because dust torques scale with disk metallicity, we propose that dust-driven outward migration may enhance the occurrence of distant giant planets in higher-metallicity systems.

  13. Averaging of multivalued differential equations

    Directory of Open Access Journals (Sweden)

    G. Grammel

    2003-04-01

    Full Text Available Nonlinear multivalued differential equations with slow and fast subsystems are considered. Under transitivity conditions on the fast subsystem, the slow subsystem can be approximated by an averaged multivalued differential equation. The approximation in the Hausdorff sense is of order O(ϵ1/3 as ϵ→0.

  14. Fuzzy Weighted Average: Analytical Solution

    NARCIS (Netherlands)

    van den Broek, P.M.; Noppen, J.A.R.

    2009-01-01

    An algorithm is presented for the computation of analytical expressions for the extremal values of the α-cuts of the fuzzy weighted average, for triangular or trapeizoidal weights and attributes. Also, an algorithm for the computation of the inverses of these expressions is given, providing exact

  15. High average power supercontinuum sources

    Indian Academy of Sciences (India)

    The physical mechanisms and basic experimental techniques for the creation of high average spectral power supercontinuum sources is briefly reviewed. We focus on the use of high-power ytterbium-doped fibre lasers as pump sources, and the use of highly nonlinear photonic crystal fibres as the nonlinear medium.

  16. Polyhedral Painting with Group Averaging

    Science.gov (United States)

    Farris, Frank A.; Tsao, Ryan

    2016-01-01

    The technique of "group-averaging" produces colorings of a sphere that have the symmetries of various polyhedra. The concepts are accessible at the undergraduate level, without being well-known in typical courses on algebra or geometry. The material makes an excellent discovery project, especially for students with some background in…

  17. Spin Torque Oscillator for High Performance Magnetic Memory

    Directory of Open Access Journals (Sweden)

    Rachid Sbiaa

    2015-06-01

    Full Text Available A study on spin transfer torque switching in a magnetic tunnel junction with perpendicular magnetic anisotropy is presented. The switching current can be strongly reduced under a spin torque oscillator (STO, and its use in addition to the conventional transport in magnetic tunnel junctions (MTJ should be considered. The reduction of the switching current from the parallel state to the antiparallel state is greater than in  the opposite direction, thus minimizing the asymmetry of the resistance versus current in the hysteresis loop. This reduction of both switching current and asymmetry under a spin torque oscillator occurs only during the writing process and does not affect the thermal stability of the free layer.

  18. Torque- and Speed Control of a Pitch Regulated Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rasila, Mika

    2003-07-01

    Variable speed operated wind turbines has the potential to reduce fatigue loads, compared to fixed speed wind turbines. With pitch controllable rotor blades limitation of the power at high wind speeds is obtained. The thesis describes different controlling aspects concerning wind turbines and how these together can be used to optimize the system's performance. Torque control is used in order to achieve reduction on the mechanical loads on the drive-train for low wind speeds and limitation of power output for high wind speeds. In the high wind speed interval torque control is effective in order to limit the output power if a sufficiently fast pitch actuator is used. In the middle wind speed interval filter utilization can be used to give a reference signal to the controller in order to reduce speed and torque variations.

  19. Micromechanical torque magnetometer with sub-monolayer sensitivity

    International Nuclear Information System (INIS)

    Min, D.H.; McCallum, A.; Russek, Stephen E.; Moreland, John

    2005-01-01

    We have developed a micromechanical torque sensor with sub-monolayer sensitivity for in situ monitoring of the magnetic moment of thin films during deposition. The film is deposited onto a microcantilever. The torque on the film is determined by measuring the deflection of the cantilever due to a small AC magnetic field perpendicular to the surface of the film. The microcantilevers have a high mechanical quality factor, large surface area, low spring constant, and high resonance frequency to improve film sensitivity to thickness. A phase-locked loop minimizes the resonance frequency shift of the cantilever due to mass loading and temperature drift that would otherwise affect the measurement of magnetic torque. The demonstrated thickness sensitivity for a Ni 0.8 Fe 0.2 film and a Ni 0.8 Fe 0.2 /Cu multilayer film is less than 0.1 nm

  20. Spin Hall effect-driven spin torque in magnetic textures

    KAUST Repository

    Manchon, Aurelien

    2011-07-13

    Current-induced spin torque and magnetization dynamics in the presence of spin Hall effect in magnetic textures is studied theoretically. The local deviation of the charge current gives rise to a current-induced spin torque of the form (1 - ΒM) × [(u 0 + αH u 0 M) ∇] M, where u0 is the direction of the injected current, H is the Hall angle and is the non-adiabaticity parameter due to spin relaxation. Since αH and ×can have a comparable order of magnitude, we show that this torque can significantly modify the current-induced dynamics of both transverse and vortex walls. © 2011 American Institute of Physics.

  1. Mechatronic Model Based Computed Torque Control of a Parallel Manipulator

    Directory of Open Access Journals (Sweden)

    Zhiyong Yang

    2008-03-01

    Full Text Available With high speed and accuracy the parallel manipulators have wide application in the industry, but there still exist many difficulties in the actual control process because of the time-varying and coupling. Unfortunately, the present-day commercial controlles cannot provide satisfying performance for its single axis linear control only. Therefore, aimed at a novel 2-DOF (Degree of Freedom parallel manipulator called Diamond 600, a motor-mechanism coupling dynamic model based control scheme employing the computed torque control algorithm are presented in this paper. First, the integrated dynamic coupling model is deduced, according to equivalent torques between the mechanical structure and the PM (Permanent Magnetism servomotor. Second, computed torque controller is described in detail for the above proposed model. At last, a series of numerical simulations and experiments are carried out to test the effectiveness of the system, and the results verify the favourable tracking ability and robustness.

  2. Mechatronic Model Based Computed Torque Control of a Parallel Manipulator

    Directory of Open Access Journals (Sweden)

    Zhiyong Yang

    2008-11-01

    Full Text Available With high speed and accuracy the parallel manipulators have wide application in the industry, but there still exist many difficulties in the actual control process because of the time-varying and coupling. Unfortunately, the present-day commercial controlles cannot provide satisfying performance for its single axis linear control only. Therefore, aimed at a novel 2-DOF (Degree of Freedom parallel manipulator called Diamond 600, a motor-mechanism coupling dynamic model based control scheme employing the computed torque control algorithm are presented in this paper. First, the integrated dynamic coupling model is deduced, according to equivalent torques between the mechanical structure and the PM (Permanent Magnetism servomotor. Second, computed torque controller is described in detail for the above proposed model. At last, a series of numerical simulations and experiments are carried out to test the effectiveness of the system, and the results verify the favourable tracking ability and robustness.

  3. Mechanics of Re-Torquing in Bolted Flange Connections

    Science.gov (United States)

    Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank

    2010-01-01

    It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application

  4. Low mass planet migration in magnetically torqued dead zones - II. Flow-locked and runaway migration, and a torque prescription

    Science.gov (United States)

    McNally, Colin P.; Nelson, Richard P.; Paardekooper, Sijme-Jan

    2018-04-01

    We examine the migration of low mass planets in laminar protoplanetary discs, threaded by large scale magnetic fields in the dead zone that drive radial gas flows. As shown in Paper I, a dynamical corotation torque arises due to the flow-induced asymmetric distortion of the corotation region and the evolving vortensity contrast between the librating horseshoe material and background disc flow. Using simulations of laminar torqued discs containing migrating planets, we demonstrate the existence of the four distinct migration regimes predicted in Paper I. In two regimes, the migration is approximately locked to the inward or outward radial gas flow, and in the other regimes the planet undergoes outward runaway migration that eventually settles to fast steady migration. In addition, we demonstrate torque and migration reversals induced by midplane magnetic stresses, with a bifurcation dependent on the disc surface density. We develop a model for fast migration, and show why the outward runaway saturates to a steady speed, and examine phenomenologically its termination due to changing local disc conditions. We also develop an analytical model for the corotation torque at late times that includes viscosity, for application to discs that sustain modest turbulence. Finally, we use the simulation results to develop torque prescriptions for inclusion in population synthesis models of planet formation.

  5. Peak Torque and Rate of Torque Development Influence on Repeated Maximal Exercise Performance: Contractile and Neural Contributions

    Science.gov (United States)

    Morel, Baptiste; Rouffet, David M.; Saboul, Damien; Rota, Samuel; Clémençon, Michel; Hautier, Christophe A.

    2015-01-01

    Rapid force production is critical to improve performance and prevent injuries. However, changes in rate of force/torque development caused by the repetition of maximal contractions have received little attention. The aim of this study was to determine the relative influence of rate of torque development (RTD) and peak torque (Tpeak) on the overall performance (i.e. mean torque, Tmean) decrease during repeated maximal contractions and to investigate the contribution of contractile and neural mechanisms to the alteration of the various mechanical variables. Eleven well-trained men performed 20 sets of 6-s isokinetic maximal knee extensions at 240°·s-1, beginning every 30 seconds. RTD, Tpeak and Tmean as well as the Rate of EMG Rise (RER), peak EMG (EMGpeak) and mean EMG (EMGmean) of the vastus lateralis were monitored for each contraction. A wavelet transform was also performed on raw EMG signal for instant mean frequency (ifmean) calculation. A neuromuscular testing procedure was carried out before and immediately after the fatiguing protocol including evoked RTD (eRTD) and maximal evoked torque (eTpeak) induced by high frequency doublet (100 Hz). Tmean decrease was correlated to RTD and Tpeak decrease (R²=0.62; pmuscle in the first milliseconds of the contraction. PMID:25901576

  6. KNEE ISOKINETIC TORQUE IMBALANCE IN FEMALE FUTSAL PLAYERS

    Directory of Open Access Journals (Sweden)

    Ana Carolina de Mello Alves Rodrigues

    Full Text Available ABSTRACT Introduction: The specificity of sports training can lead to muscle specialization with a possible change in the natural hamstring/quadriceps torque ratio (HQ ratio, constituting a risk factor for muscle injury at the joint angles in which muscle imbalance may impair dynamic stability. Objective: The aim was to evaluate the torque distribution of the hamstrings and quadriceps and the HQ ratio throughout the range of motion in order to identify possible muscle imbalances at the knee of female futsal athletes. Methods: Nineteen amateur female futsal athletes had their dominant limb HQ ratio evaluated in a series of five maximum repetitions of flexion/extension of the knee at 180°/second in the total joint range of motion (30° to 80°. The peak flexor and extensor torque and the HQ ratio (% were compared each 5° of knee motion using one-way repeated measures ANOVA and Tukey’s post hoc test (p<0.05 to determine the joint angles that present muscular imbalance. Results: Quadriceps torque was higher than 50° to 60° of knee flexion, while hamstrings torque was higher than 55° to 65°. The HQ ratio presented lower values than 30° to 45° of knee flexion and four athletes presented values lower than 60%, which may represent a risk of injury. However, the HQ ratio calculated by the peak torque showed only one athlete with less than 60%. Conclusion: The HQ ratio analyzed throughout the knee range of motion allowed identifying muscle imbalance at specific joint angles in female futsal players.

  7. When good = better than average

    Directory of Open Access Journals (Sweden)

    Don A. Moore

    2007-10-01

    Full Text Available People report themselves to be above average on simple tasks and below average on difficult tasks. This paper proposes an explanation for this effect that is simpler than prior explanations. The new explanation is that people conflate relative with absolute evaluation, especially on subjective measures. The paper then presents a series of four studies that test this conflation explanation. These tests distinguish conflation from other explanations, such as differential weighting and selecting the wrong referent. The results suggest that conflation occurs at the response stage during which people attempt to disambiguate subjective response scales in order to choose an answer. This is because conflation has little effect on objective measures, which would be equally affected if the conflation occurred at encoding.

  8. Heat engine and electric motor torque distribution strategy for a hybrid electric vehicle

    Science.gov (United States)

    Boberg, Evan S.; Gebby, Brian P.

    1999-09-28

    A method is provided for controlling a power train system for a hybrid electric vehicle. The method includes a torque distribution strategy for controlling the engine and the electric motor. The engine and motor commands are determined based upon the accelerator position, the battery state of charge and the amount of engine and motor torque available. The amount of torque requested for the engine is restricted by a limited rate of rise in order to reduce the emissions from the engine. The limited engine torque is supplemented by motor torque in order to meet a torque request determined based upon the accelerator position.

  9. Skyrmionic spin Seebeck effect via dissipative thermomagnonic torques

    Science.gov (United States)

    Kovalev, Alexey A.

    2014-06-01

    We derive thermomagnonic torque and its "β-type" dissipative correction from the stochastic Landau-Lifshitz-Gilbert equation. The β-type dissipative correction describes viscous coupling between magnetic dynamics and magnonic current and it stems from spin mistracking of the magnetic order. We show that thermomagnonic torque is important for describing temperature gradient induced motion of skyrmions in helical magnets while dissipative correction plays an essential role in generating transverse Magnus force. We propose to detect such skyrmionic motion by employing the transverse spin Seebeck effect geometry.

  10. Magnetic Circuit & Torque Analysis Of Brushless DC Motor

    Directory of Open Access Journals (Sweden)

    Arif J. Abbas

    2013-05-01

    Full Text Available       This work is concerned with magnetic and torque analysis of BLDCM and with development of a method of designing BLDCM that have symmetric winding on the rotor .make significant contribution to the rotor inductance position difficult. It is also show that the prediction detent torque can be extremely sensitive to the permanent magnet by altering magnet arc width. Finally, simple lumped models that allow one to predict motor performance and characteristics as a function of main dimension, magnet residual flux density and phase current are developed. These models are used as a basis for an approach to designing BLDCM

  11. Determination of Ultimate Torque for Multiply Connected Cross Section Rod

    Directory of Open Access Journals (Sweden)

    V. L. Danilov

    2015-01-01

    Full Text Available The aim of this work is to determine load-carrying capability of the multiply cross-section rod. This calculation is based on the model of the ideal plasticity of the material, so that the desired ultimate torque is a torque at which the entire cross section goes into a plastic state.The article discusses the cylindrical multiply cross-section rod. To satisfy the equilibrium equation and the condition of plasticity simultaneously, two stress function Ф and φ are introduced. By mathematical transformations it has been proved that Ф is constant along the path, and a formula to find its values on the contours has been obtained. The paper also presents the rationale of the line of stress discontinuity and obtained relationships, which allow us to derive the equations break lines for simple interaction of neighboring circuits, such as two lines, straight lines and circles, circles and a different sign of the curvature.After substitution into the boundary condition at the end of the stress function Ф and mathematical transformations a formula is obtained to determine the ultimate torque for the multiply cross-section rod.Using the doubly connected cross-section and three-connected cross-section rods as an example the application of the formula of ultimate torque is studied.For doubly connected cross-section rod, the paper offers a formula of the torque versus the radius of the rod, the aperture radius and the distance between their centers. It also clearly demonstrates the torque dependence both on the ratio of the radii and on the displacement of hole. It is shown that the value of the torque is more influenced by the displacement of hole, rather than by the ratio of the radii.For the three-connected cross-section rod the paper shows the integration feature that consists in selection of a coordinate system. As an example, the ultimate torque is found by two methods: analytical one and 3D modeling. The method of 3D modeling is based on the Nadai

  12. Computations of Torque-Balanced Coaxial Rotor Flows

    Science.gov (United States)

    Yoon, Seokkwan; Chan, William M.; Pulliam, Thomas H.

    2017-01-01

    Interactional aerodynamics has been studied for counter-rotating coaxial rotors in hover. The effects of torque balancing on the performance of coaxial-rotor systems have been investigated. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model. Computational results for an experimental model are compared to available data. The results for a coaxial quadcopter vehicle with and without torque balancing are discussed. Understanding interactions in coaxial-rotor flows would help improve the design of next-generation autonomous drones.

  13. Age-related differences in lower-limb muscle cross-sectional area and torque production in boys with Duchenne muscular dystrophy.

    Science.gov (United States)

    Mathur, Sunita; Lott, Donovan J; Senesac, Claudia; Germain, Sean A; Vohra, Ravneet S; Sweeney, H Lee; Walter, Glenn A; Vandenborne, Krista

    2010-07-01

    To examine the relationship between lower-extremity muscle cross-sectional area, muscle strength, specific torque, and age in ambulatory boys with Duchenne muscular dystrophy (DMD) compared with controls. Observational cross-sectional study. University research setting. Volunteer sample of boys with DMD (n=22) and healthy control boys (n=10), ages 5 through 14 years. Not applicable. Maximal muscle cross-sectional area (CSA(max)) assessed by magnetic resonance imaging of quadriceps, plantarflexors (PFs) and dorsiflexors (DFs), peak isometric torque from dynamometry, and timed functional tests. The average CSA(max) of the triceps surae muscle group was approximately 60% higher in boys with DMD compared with controls (39.1+/-13.6 cm(2) vs 24.5+/-9.3 cm(2); P=.002), while the tibialis anterior muscle showed age-appropriate increases in CSA(max). The increase in quadriceps CSA(max) was also distinctly different in boys with DMD compared with controls. Specific torque (ie, peak torque/CSA(max)) was impaired in all 3 muscles groups, with the knee extensor (KE) and PF muscles showing 4-fold, and the DF muscles 2-fold, higher values in controls compared with boys with DMD. Large age-related gains in specific torque were observed in all 3 muscle groups of control subjects, which were absent in ambulatory boys with DMD. Correlations were observed between performance on functional tasks and quadriceps and PF torque production (r=-.45 to -.57, Pmuscle cross-sectional area and specific torque production in lower-extremity muscles showed distinctly different patterns in the KE, PF, and DF muscles of boys with DMD compared with controls. Copyright 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  14. Peak torque and muscle balance in the knees of young U-15 and U-17 soccer athletes playing various tactical positions.

    Science.gov (United States)

    Chiamonti Bona, Cleiton; Tourinho Filho, Hugo; Izquierdo, Mikel; Pires Ferraz, Ricardo M; Marques, Mário C

    2017-01-01

    Soccer is a sport that is practiced worldwide and has been investigated in its various aspects, particularly muscle strength, which is an essential motor skill for sports performance. The objective of this study was to investigate the peak torque and muscle balance on the knee extensor and flexor of young soccer players in the tactical positions of goalkeeper, defender, full back, midfielder, defensive midfielder and striker, as well as to determine which field position has the highest peak torque. Forty-nine male players were recruited and divided into two categories during the preparatory period of the season: the Under-15 (U-15) group (N.=23, mean age 14.7±0.5 years, body mass 58.2±10.5 kg, body height 168.5±7.6 cm), and the Under-17 (U-17) group (N.=26, mean age 16.8±0.4 years, body mass 69.2±7.9 kg, body height 176.2±6.6 cm). The U-17 athletes presented a higher peak torque in all the movements of flexion and extension in the two angular velocities (i.e. 60°/s and 300°/s), but only the dominant knee extensor at 300°/s was significantly different between the two categories as well as the percentage change in peak torque compared between U-15 and U-17 was always above 20%. The peak torque variation in the U-17 category (i.e. mostly above 20%) highlights a higher peak torque compared to U-15 athletes. The muscular deficit of the two categories presented a low average of 10-15%, indicating a good muscle balance between knee extensors and flexors. Finally, goalkeepers and defenders achieved the highest peak torque amongst the field positions.

  15. The effects of short-term exercise training on peak-torque are time- and fiber-type dependent.

    Science.gov (United States)

    Ureczky, Dóra; Vácz, Gabriella; Costa, Andreas; Kopper, Bence; Lacza, Zsombor; Hortobágyi, Tibor; Tihanyi, József

    2014-08-01

    We examined the susceptibility of fast and slow twitch muscle fibers in the quadriceps muscle to eccentric exercise-induced muscle damage. Nine healthy men (age: 22.5 ± 1.6 years) performed maximal eccentric quadriceps contractions at 120°·s-1 over a 120° of knee joint range of motion for 6 consecutive days. Biopsies were taken from the vastus lateralis muscle before repeated bouts of eccentric exercise on the third and seventh day. Immunohistochemical procedures were used to determine fiber composition and fibronectin activity. Creatine kinase (CK) and lactate dehydrogenase (LDH) were determined in serum. Average torque was calculated in each day for each subject. Relative to baseline, average torque decreased 37.4% till day 3 and increased 43.0% from the day 3 to day 6 (p muscles of 2 subjects with high fast fiber percentage. Peak torque and muscle fiber-type composition measured at baseline showed a strong positive association on day 3 (r = 0.76, p muscles with slow fiber dominance were more susceptible to repeated bouts of eccentric exercise than fast fiber dominance muscles. The data suggest that the responses to repeated bouts of eccentric exercise are fiber-type-dependent in the quadriceps muscle, which can be the basis for the design of individualized strength training protocols.

  16. Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques.

    Directory of Open Access Journals (Sweden)

    Takahito Suzuki

    Full Text Available Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10-100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG, lateral gastrocnemius (LG, and soleus muscles and quantified using the average rectified value (ARV. At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r2 > 0.65. The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006. Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively. These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis.

  17. Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques.

    Science.gov (United States)

    Suzuki, Takahito; Kinugasa, Ryuta; Fukashiro, Senshi

    2017-01-01

    Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10-100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus muscles and quantified using the average rectified value (ARV). At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r2 > 0.65). The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006). Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively). These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis.

  18. Torque characteristics of double-stator permanent magnet synchronous machines

    Directory of Open Access Journals (Sweden)

    Awah Chukwuemeka Chijioke

    2017-12-01

    Full Text Available The torque profile of a double-stator permanent magnet (PM synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unbalanced magnetic force. The most promising flux-weakening potential is revealed in 13- and 7-rotor pole machines. Moreover, the machines having different rotor/stator (Nr/Ns pole combinations of the form Nr = Ns ± 1 have balanced and symmetric static torque waveforms variation with the rotor position in contrast to the machines having Nr = Ns ± 2. Further, the inductance results of the analyzed machines reveal that the machines with odd rotor pole numbers have better fault-tolerant capability than their even rotor pole equivalents. A prototype of the developed double-stator machine having a 13-pole rotor is manufactured and tested for verification.

  19. Macroscopic bulk cohesion and torque for wet granular materials

    NARCIS (Netherlands)

    Roy, Sudeshna; Luding, Stefan; Weinhart, Thomas

    2015-01-01

    Wet granular materials in steady-state in a quasi-static flow have been studied with discrete particle simulations. The total torque is an experimentally accessible macroscopic quantity that can be used to investigate the shear strength, bulk cohesion and other properties of the materials. We report

  20. Torque control of underactuated tendon-driven fingers

    Directory of Open Access Journals (Sweden)

    M. E. Abdallah

    2011-02-01

    Full Text Available Given an underactuated tendon-driven finger, the finger posture is underdetermined and can move freely ("flop" in a region of slack tendons. This work shows that such an underactuated finger can be operated in tendon force control (rather than position control with effective performance. The force control eliminates the indeterminate slack while commanding a parameterized space of desired torques. The torque will either push the finger to the joint limits or wrap around an external object with variable torque – behavior that is sufficient for primarily gripping fingers. In addition, introducing asymmetric joint radii to the design allows the finger to command an expanded range of joint torques and to scan an expanded set of external surfaces. This study is motivated by the design and control of the secondary fingers of the NASA-GM R2 humanoid hand.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  1. Improving the performance of hysteresis direct torque control of ...

    Indian Academy of Sciences (India)

    This paper describes an active filter topology to improve the performance of hysteresis direct torque control (HDTC) of interior permanent magnet synchronous motor (IPMSM). The filter topology consists of an active filter and two RLC filters, and is connected to the main power circuit through a 1:1 transformer. The active filter ...

  2. Torque and optical traps | Ibeneche | African Journal of Biotechnology

    African Journals Online (AJOL)

    Optical traps are an important tool for research in the field of single molecule biophysics. Recent advances in optical trapping have extended their functionality from simple linear manipulation and measurement of forces, to now the ability to rotate objects and measure torques. This mini review summarizes these recent ...

  3. 14 CFR 23.397 - Limit control forces and -torques.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Limit control forces and -torques. 23.397 Section 23.397 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION.... Wheel 3 50 D in.-lbs 4 40 D in.-lbs.4 Elevator: Stick 167 lbs 100 lbs. Wheel (symmetrical) 200 lbs 100...

  4. Spin-Orbit Torques in ferrimagnetic GdFeCo

    Science.gov (United States)

    Roschewsky, Niklas; Lambert, Charles-Henri; Salahuddin, Sayeef

    Recently spin-orbit torques in antiferromagnets received a lot of attention due to intrinsic high frequency dynamics as well as robustness against perturbations from external magnetic fields. Here, we report on spin-orbit torque (SOT) switching in ferrimagnetic Gdx (Fe90Co10)100-x films on both sides of the magnetic compensation point. In addition to current driven switching experiments we performed harmonic Hall measurements of the effective SOT fields. We find that both the Slonczewski torque as well as the field-like torque diverge at the magnetization compensation point. However, the effective spin Hall angle ξ = (2 | e | / ℏ) MStFM (Heff / | jHM |) is found to be roughly constant across the investigated composition range. This provides important insight into the the angular momentum transfer process in ferrimagnets. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Science and Engineering Division of the U.S. Department of Energy under Contract No. DE-AC02-05-CH11231 within the NEMM program (KC2204).

  5. Design and Comparison Direct Torque Control Techniques for Induction Motors

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Kazmierkowski, Marian P.; Zelechowski, Marcin

    2005-01-01

    In this paper a comparison of two significant control methods of induction motor are presented. The first one is a classical Direct Torque and Flux Control (DTC) and is compared with a scheme, which uses Space Vector Modulator (DTC-SVM). A comparison in respect to dynamic and steady state...

  6. Self-similar spherical collapse with tidal torque

    Science.gov (United States)

    Zukin, Phillip; Bertschinger, Edmund

    2010-11-01

    N-body simulations have revealed a wealth of information about dark matter halos; however, their results are largely empirical. Using analytic means, we attempt to shed light on simulation results by generalizing the self-similar secondary infall model to include tidal torque. In this first of two papers, we describe our halo formation model and compare our results to empirical mass profiles inspired by N-body simulations. Each halo is determined by four parameters. One parameter sets the mass scale and the other three define how particles within a mass shell are torqued throughout evolution. We choose torque parameters motivated by tidal torque theory and N-body simulations and analytically calculate the structure of the halo in different radial regimes. We find that angular momentum plays an important role in determining the density profile at small radii. For cosmological initial conditions, the density profile on small scales is set by the time rate of change of the angular momentum of particles as well as the halo mass. On intermediate scales, however, ρ∝r-2, while ρ∝r-3 close to the virial radius.

  7. 40 CFR 91.306 - Dynamometer torque cell calibration.

    Science.gov (United States)

    2010-07-01

    ... dynamometers (±five degrees). For vertical shaft dynamometers, a pulley system may be used to convert the... torque, adjust or repair the system. Repeat steps in paragraphs (a)(1) through (a)(6) of this section with the adjusted or repaired system. (b) Option. A master load-cell or transfer standard may be used...

  8. 40 CFR 90.306 - Dynamometer torque cell calibration.

    Science.gov (United States)

    2010-07-01

    ... for horizontal shaft dynamometers (±five degrees). For vertical shaft dynamometers, a pulley system... within two percent of the calculated torque, adjust or repair the system. Repeat steps in paragraphs (a)(1) through (a)(6) of this section with the adjusted or repaired system. (b) Option. A master load...

  9. Improvement of Torque Production in Single-Phase Induction Motors

    African Journals Online (AJOL)

    OLUWASOGO

    and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM inverter to drive the existing motor is implemented in MATLAB/Simulink environment in this work.

  10. Evaluation of fracture torque resistance of orthodontic mini-implants.

    Science.gov (United States)

    Dalla Rosa, Fernando; Burmann, Paola Fp; Ruschel, Henrique C; Vargas, Ivana A; Kramer, Paulo F

    2016-12-01

    This study sought to assess the fracture torque resistance of mini-implants used for orthodontic anchorage. Five commercially available brands of mini-implants were used (SIN®, CONEXÃO®, NEODENT®, MORELLI®, andFORESTADENT®). Ten mini-implants of each diameter of each brand were tested, for a total 100 specimens. The mini-implants were subject to a static torsion test as described in ASTMstandard F543. Analysis of variance (ANOVA) with the Tukey multiple comparisons procedure was used to assess results. Overall, mean fracture strength ranged from 15.7 to 70.4 N·cm. Mini-implants with larger diameter exhibited higher peak torque values at fracture and higher yield strength, regardless of brand. In addition, significant differences across brands were observed when implants were stratified by diameter. In conclusion, larger mini-implant diameter is associated with increased fracture torque resistance. Additional information on peak torque values at fracture of different commercial brands of mini-implants may increase the success rate of this orthodontic anchorage modality. Sociedad Argentina de Investigación Odontológica.

  11. Effect of Filament Fineness on Composite Yarn Residual Torque

    Directory of Open Access Journals (Sweden)

    Sarıoğlu Esin

    2018-03-01

    Full Text Available Yarn residual torque or twist liveliness occurs when the twist is imparted to spin the fibers during yarn formation. It causes yarn snarling, which is an undesirable property and can lead the problems for further processes such as weaving and knitting. It affects the spirality of knitted fabrics and skewness of woven fabrics. Generally, yarn residual torque depends on yarn twist, yarn linear density, and fiber properties used. Composite yarns are widely produced to exploit two yarns with different properties such on optimum way at the same time and these yarns can be produced by wrapping sheath fibers around filament core fiber with a certain twist. In this study, the effect of filament fineness used as core component of composite yarn on residual torque was analyzed. Thus, the false twist textured polyester filament yarns with different filament fineness were used to produce composite yarns with different yarn count. The variance analysis was performed to determine the significance of twist liveliness of filament yarns and yarn count on yarn twist liveliness. Results showed that there is a statistically significant differences at significance level of α=0.05 between filament fineness and yarn residual torque of composite yarns.

  12. Large Torque Variations in Two Soft Gamma Repeaters

    NARCIS (Netherlands)

    Woods, P.M.; Kouveliotou, C.; Göğüş, E.; Finger, M.H.; Swank, J.; Markwardt, C.B.; Hurley, K.; van der Klis, M.

    2002-01-01

    We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor

  13. New species of Torque Teno miniviruses infecting gorillas and chimpanzees

    Czech Academy of Sciences Publication Activity Database

    Hrazdilová, K.; Slaninková, E.; Brožová, K.; Modrý, David; Vodička, R.; Celer, V.

    2016-01-01

    Roč. 487, JAN (2016), s. 207-214 ISSN 0042-6822 Institutional support: RVO:60077344 Keywords : Anellovirus * Torque Teno mini virus * Great apes * Non-human primates * Genome sequence Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 3.353, year: 2016

  14. IPMSM Motion-Sensorless Direct Torque and Flux Control

    DEFF Research Database (Denmark)

    Pitict, Christian Ilie; Andreescu, Gheorghe-Daniel; Blaabjerg, Frede

    2005-01-01

    The paper presents a rather comprehensive implementation of a wide speed motion-sensorless control of IPMSM drives via direct torque and flux control (DTFC) with space vector modulation (SVM). Signal injection with only one D-module vector filter and phase-locked loop (PLL) observer is used at low...

  15. Design of direct drive robot using indigenously developed d.c. torque motors

    Science.gov (United States)

    Athani, Vithal V.

    The range of high-performance torque motors, which were indigenously developed for use in multistage satellite launch vehicles, is described. The main features that set dc torque motors apart from dc servomotors are: high peak torque, power, and current over short periods of operation, low speed of operation, obviating the need for gearing, high torque/inertia and torque/weight ratios, and high figure of merit = torque/sq rt watt ratio. The dc torque motors are eminently suited to high-performance applications requiring high torque at low speed of operation, such as aircraft and missile control surface actuation, control of multistage satellite launch vehicles, certain computer peripherals like magnetic tape transports and hard disk drives, and robotics, CNC systems, and machine tool control.

  16. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2014-05-28

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green\\'s function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  17. Development of Fast Response SME TiNi Foam Torque Tubes, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase I, Shape Change Technologies had developed a process to manufacture net shape TiNi foam torque tubes that demonstrated the shape memory effect. The torque...

  18. The relation between granule size, granule stickiness, and torque in the high-shear granulation process

    NARCIS (Netherlands)

    Bouwman, A.M.; Henstra, M.J.; Hegge, J.J.M.E.; Zhang, Z.; Ingram, A.; Seville, J.P.K.; Frijlink, H.W.

    2005-01-01

    Purpose. To investigate the background of the observed relationship between measured torque and granule size in high-shear granulation processes. Methods. Torque was measured during the granulation process; the behavior of individual wet granules during compaction was investigated using

  19. Spin Orbit Interaction Engineering for beyond Spin Transfer Torque memory

    Science.gov (United States)

    Wang, Kang L.

    Spin transfer torque memory uses electron current to transfer the spin torque of electrons to switch a magnetic free layer. This talk will address an alternative approach to energy efficient non-volatile spintronics through engineering of spin orbit interaction (SOC) and the use of spin orbit torque (SOT) by the use of electric field to improve further the energy efficiency of switching. I will first discuss the engineering of interface SOC, which results in the electric field control of magnetic moment or magneto-electric (ME) effect. Magnetic memory bits based on this ME effect, referred to as magnetoelectric RAM (MeRAM), is shown to have orders of magnitude lower energy dissipation compared with spin transfer torque memory (STTRAM). Likewise, interests in spin Hall as a result of SOC have led to many advances. Recent demonstrations of magnetization switching induced by in-plane current in heavy metal/ferromagnetic heterostructures have been shown to arise from the large SOC. The large SOC is also shown to give rise to the large SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics. In particular, we will show the magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. This large SOT is shown to come from the spin-momentum locked surface states of TI, which may further lead to innovative low power applications. I will also describe other related physics of SOC at the interface of anti-ferromagnetism/ferromagnetic structure and show the control exchange bias by electric field for high speed memory switching. The work was in part supported by ERFC-SHINES, NSF, ARO, TANMS, and FAME.

  20. Preliminary results on noncollocated torque control of space robot actuators

    Science.gov (United States)

    Tilley, Scott W.; Francis, Colin M.; Emerick, Ken; Hollars, Michael G.

    1989-01-01

    In the Space Station era, more operations will be performed robotically in space in the areas of servicing, assembly, and experiment tending among others. These robots may have various sets of requirements for accuracy, speed, and force generation, but there will be design constraints such as size, mass, and power dissipation limits. For actuation, a leading motor candidate is a dc brushless type, and there are numerous potential drive trains each with its own advantages and disadvantages. This experiment uses a harmonic drive and addresses some inherent limitations, namely its backdriveability and low frequency structural resonances. These effects are controlled and diminished by instrumenting the actuator system with a torque transducer on the output shaft. This noncollocated loop is closed to ensure that the commanded torque is accurately delivered to the manipulator link. The actuator system is modelled and its essential parameters identified. The nonlinear model for simulations will include inertias, gearing, stiction, flexibility, and the effects of output load variations. A linear model is extracted and used for designing the noncollocated torque and position feedback loops. These loops are simulated with the structural frequency encountered in the testbed system. Simulation results are given for various commands in position. The use of torque feedback is demonstrated to yield superior performance in settling time and positioning accuracy. An experimental setup being finished consists of a bench mounted motor and harmonic drive actuator system. A torque transducer and two position encoders, each with sufficient resolution and bandwidth, will provide sensory information. Parameters of the physical system are being identified and matched to analytical predictions. Initial feedback control laws will be incorporated in the bench test equipment and various experiments run to validate the designs. The status of these experiments is given.

  1. PREFACE: The Science of Making Torque from Wind 2012

    Science.gov (United States)

    2014-12-01

    The European Academy of Wind Energy (eawe) was pleased to announce its 4th scientific conference The Science of Making Torque from Wind. Predecessors have successfully been arranged in Delft, The Netherlands (2004), Lyngby, Denmark (2007) and Heraklion, Greece (2010). During the years the Torque Conference has established itself as Europe's leading scientific wind energy conference. The 2012 edition had been organized in the same tradition. More than 300 experts from academia and industry discussed the latest results and developments in fundamental and applied wind energy research, making this Science of Making Torque from Wind conference the largest one to that date. The seven keynote lectures provided the delegates with a unique overview on the state-of-the-art of science and technology. In over twenty sessions the participants discussed the most recent results in wind energy research. From numerical models to sophisticated experiments, from flow optimizations to structural designs, the numerous presentations covered a huge spectrum of ongoing scientific activities. The proceedings of the Torque 2012 combine the 110 papers that have passed the review process. We would like to thank all those who have been involved in organizing the conference and putting together these proceedings, including keynote speakers, session chairs and the enormous amount of reviewers involved. We are especially grateful to Gijs van Kuik for his untiring support. We also deeply appreciate the logistical support and technical services of the University of Oldenburg and the financial support of the State of Lower Saxony. At IOP we would like to thank Anete Ashton for her continuous encouraging support. We are looking forward to all future Torque Conferences, offering an excellent platform for the exchange of the latest and greatest scientific developments in the field of wind energy. Oldenburg, Germany, October 2014 Elke Seidel, Detlev Heinemann, Martin Kühn, Joachim Peinke and Stephan

  2. Dimensionality of joint torques and muscle patterns for reaching

    Directory of Open Access Journals (Sweden)

    Marta eRusso

    2014-03-01

    Full Text Available Muscle activities underlying many motor behaviors can be generated by a small number of basic activation patterns with specific features shared across movement conditions. Such low-dimensionality suggests that the central nervous system (CNS relies on a modular organization to simplify control. However, the relationship between the dimensionality of muscle patterns and that of joint torques is not fixed, because of redundancy and non-linearity in mapping the former into the latter, and needs to be investigated. We compared the torques acting at four arm joints during fast reaching movements in different directions in the frontal and sagittal planes and the underlying muscle patterns. The dimensionality of the non-gravitational components of torques and muscle patterns in the spatial, temporal, and spatiotemporal domains was estimated by multidimensional decomposition techniques. The spatial organization of torques was captured by two or three generators, indicating that not all the available coordination patterns are employed by the CNS. A single temporal generator with a biphasic profile was identified, generalizing previous observations on a single plane. The number of spatiotemporal generators was equal to the product of the spatial and temporal dimensionalities and their organization was essentially synchronous. Muscle pattern dimensionalities were higher than torques dimensionalities but also higher than the minimum imposed by the inherent non-negativity of muscle activations. The spatiotemporal dimensionality of the muscle patterns was lower than the product of their spatial and temporal dimensionality, indicating the existence of specific asynchronous coordination patterns. Thus, the larger dimensionalities of the muscle patterns may be required for CNS to overcome the non-linearities of the musculoskeletal system and to flexibly generate endpoint trajectories with simple kinematic features using a limited number of building blocks.

  3. Spin-transfer torque generated by a topological insulator

    KAUST Repository

    Mellnik, A. R.

    2014-07-23

    Magnetic devices are a leading contender for the implementation of memory and logic technologies that are non-volatile, that can scale to high density and high speed, and that do not wear out. However, widespread application of magnetic memory and logic devices will require the development of efficient mechanisms for reorienting their magnetization using the least possible current and power. There has been considerable recent progress in this effort; in particular, it has been discovered that spin-orbit interactions in heavy-metal/ferromagnet bilayers can produce strong current-driven torques on the magnetic layer, via the spin Hall effect in the heavy metal or the Rashba-Edelstein effect in the ferromagnet. In the search for materials to provide even more efficient spin-orbit-induced torques, some proposals have suggested topological insulators, which possess a surface state in which the effects of spin-orbit coupling are maximal in the sense that an electron\\' s spin orientation is fixed relative to its propagation direction. Here we report experiments showing that charge current flowing in-plane in a thin film of the topological insulator bismuth selenide (Bi2Se3) at room temperature can indeed exert a strong spin-transfer torque on an adjacent ferromagnetic permalloy (Ni81Fe19) thin film, with a direction consistent with that expected from the topological surface state. We find that the strength of the torque per unit charge current density in Bi 2Se3 is greater than for any source of spin-transfer torque measured so far, even for non-ideal topological insulator films in which the surface states coexist with bulk conduction. Our data suggest that topological insulators could enable very efficient electrical manipulation of magnetic materials at room temperature, for memory and logic applications. © 2014 Macmillan Publishers Limited. All rights reserved.

  4. Spinal circuits can accommodate interaction torques during multijoint limb movements

    Directory of Open Access Journals (Sweden)

    Thomas eBuhrmann

    2014-11-01

    Full Text Available The dynamic interaction of limb segments during movements that involve multiple joints creates torques in one joint due to motion about another. Evidence shows that such interaction torques are taken into account during the planning or control of movement in humans. Two alternative hypotheses could explain the compensation of these dynamic torques. One involves the use of internal models to centrally compute predicted interaction torques and their explicit compensation through anticipatory adjustment of descending motor commands. The alternative, based on the equilibrium-point hypothesis, claims that descending signals can be simple and related to the desired movement kinematics only, while spinal feedback mechanisms are responsible for the appropriate creation and coordination of dynamic muscle forces. Partial supporting evidence exists in each case. However, until now no model has explicitly shown, in the case of the second hypothesis, whether peripheral feedback is really sufficient on its own for coordinating the motion of several joints while at the same time accommodating intersegmental interaction torques. Here we propose a minimal computational model to examine this question. Using a biomechanics simulation of a two-joint arm controlled by spinal neural circuitry, we show for the first time that it is indeed possible for the neuromusculoskeletal system to transform simple descending control signals into muscle activation patterns that accommodate interaction forces depending on their direction and magnitude. This is achieved without the aid of any central predictive signal. Even though the model makes various simplifications and abstractions compared to the complexities involved in the control of human arm movements, the finding lends plausibility to the hypothesis that some multijoint movements can in principle be controlled even in the absence of internal models of intersegmental dynamics or learned compensatory motor signals.

  5. Online Estimation of Clutch Drag Torque in Wet Dual Clutch Transmission Based on Recursive Least Squares

    OpenAIRE

    Hongkui Li; Tongli Lu; Jianwu Zhang

    2016-01-01

    This paper focuses on developing an estimation method of clutch drag torque in wet DCT. The modelling of clutch drag torque is investigated. As the main factor affecting the clutch drag torque, dynamic viscosity of oil is discussed. The paper proposes an estimation method of clutch drag torque based on recursive least squares by utilizing the dynamic equations of gear shifting synchronization process. The results demonstrate that the estimation method has good accuracy and efficiency.

  6. Torque Split Strategy for Parallel Hybrid Electric Vehicles with an Integrated Starter Generator

    OpenAIRE

    Fu, Zhumu; Gao, Aiyun; Wang, Xiaohong; Song, Xiaona

    2014-01-01

    This paper presents a torque split strategy for parallel hybrid electric vehicles with an integrated starter generator (ISG-PHEV) by using fuzzy logic control. By combining the efficiency map and the optimum torque curve of the internal combustion engine (ICE) with the state of charge (SOC) of the batteries, the torque split strategy is designed, which manages the ICE within its peak efficiency region. Taking the quantified ICE torque, the quantified SOC of the batteries, and the quantified I...

  7. Asymmetries in wing inertial and aerodynamic torques contribute to steering in flying insects.

    Science.gov (United States)

    Jankauski, Mark; Daniel, T L; Shen, I Y

    2017-06-08

    Maneuvering in both natural and artificial miniature flying systems is assumed to be dominated by aerodynamic phenomena. To explore this, we develop a flapping wing model integrating aero and inertial dynamics. The model is applied to an elliptical wing similar to the forewing of the Hawkmoth Manduca sexta and realistic kinematics are prescribed. We scrutinize the stroke deviation phase, as it relates to firing latency in airborne insect steering muscles which has been correlated to various aerial maneuvers. We show that the average resultant force production acting on the body largely arises from wing pitch and roll and is insensitive to the phase and amplitude of stroke deviation. Inclusion of stroke deviation can generate significant averaged aerodynamic torques at steady-state and adjustment of its phase can facilitate body attitude control. Moreover, averaged wing angular momentum varies with stroke deviation phase, implying a non-zero impulse during a time-dependent phase shift. Simulations show wing inertial and aerodynamic impulses are of similar magnitude during short transients whereas aerodynamic impulses dominate during longer transients. Additionally, inertial effects become less significant for smaller flying insects. Body yaw rates arising from these impulses are consistent with biologically measured values. Thus, we conclude (1) modest changes in stroke deviation can significantly affect steering and (2) both aerodynamic and inertial torques are critical to maneuverability, the latter of which has not widely been considered. Therefore, the addition of a control actuator modulating stroke deviation may decouple lift/thrust production from steering mechanisms in flapping wing micro aerial vehicles and increase vehicle dexterity through inertial trajectory shaping.

  8. Condition monitoring of gearboxes using synchronously averaged electric motor signals

    Science.gov (United States)

    Ottewill, J. R.; Orkisz, M.

    2013-07-01

    Due to their prevalence in rotating machinery, the condition monitoring of gearboxes is extremely important in the minimization of potentially dangerous and expensive failures. Traditionally, gearbox condition monitoring has been conducted using measurements obtained from casing-mounted vibration transducers such as accelerometers. A well-established technique for analyzing such signals is the synchronous signal average, where vibration signals are synchronized to a measured angular position and then averaged from rotation to rotation. Driven, in part, by improvements in control methodologies based upon methods of estimating rotor speed and torque, induction machines are used increasingly in industry to drive rotating machinery. As a result, attempts have been made to diagnose defects using measured terminal currents and voltages. In this paper, the application of the synchronous signal averaging methodology to electric drive signals, by synchronizing stator current signals with a shaft position estimated from current and voltage measurements is proposed. Initially, a test-rig is introduced based on an induction motor driving a two-stage reduction gearbox which is loaded by a DC motor. It is shown that a defect seeded into the gearbox may be located using signals acquired from casing-mounted accelerometers and shaft mounted encoders. Using simple models of an induction motor and a gearbox, it is shown that it should be possible to observe gearbox defects in the measured stator current signal. A robust method of extracting the average speed of a machine from the current frequency spectrum, based on the location of sidebands of the power supply frequency due to rotor eccentricity, is presented. The synchronous signal averaging method is applied to the resulting estimations of rotor position and torsional vibration. Experimental results show that the method is extremely adept at locating gear tooth defects. Further results, considering different loads and different

  9. Flexible time domain averaging technique

    Science.gov (United States)

    Zhao, Ming; Lin, Jing; Lei, Yaguo; Wang, Xiufeng

    2013-09-01

    Time domain averaging(TDA) is essentially a comb filter, it cannot extract the specified harmonics which may be caused by some faults, such as gear eccentric. Meanwhile, TDA always suffers from period cutting error(PCE) to different extent. Several improved TDA methods have been proposed, however they cannot completely eliminate the waveform reconstruction error caused by PCE. In order to overcome the shortcomings of conventional methods, a flexible time domain averaging(FTDA) technique is established, which adapts to the analyzed signal through adjusting each harmonic of the comb filter. In this technique, the explicit form of FTDA is first constructed by frequency domain sampling. Subsequently, chirp Z-transform(CZT) is employed in the algorithm of FTDA, which can improve the calculating efficiency significantly. Since the signal is reconstructed in the continuous time domain, there is no PCE in the FTDA. To validate the effectiveness of FTDA in the signal de-noising, interpolation and harmonic reconstruction, a simulated multi-components periodic signal that corrupted by noise is processed by FTDA. The simulation results show that the FTDA is capable of recovering the periodic components from the background noise effectively. Moreover, it can improve the signal-to-noise ratio by 7.9 dB compared with conventional ones. Experiments are also carried out on gearbox test rigs with chipped tooth and eccentricity gear, respectively. It is shown that the FTDA can identify the direction and severity of the eccentricity gear, and further enhances the amplitudes of impulses by 35%. The proposed technique not only solves the problem of PCE, but also provides a useful tool for the fault symptom extraction of rotating machinery.

  10. Turn-on Angle Control Using Modified Torque Sharing Function for Torque Ripple Reduction in Switched Reluctance Motors

    Directory of Open Access Journals (Sweden)

    Mehrdad Daryanush

    2015-07-01

    Full Text Available In the recent years, the use of switched reluctance motors (SRM in industrial applications has been increased. In this regard, a large amount of research studies have been conducted on controlling the speed and torque of the aforementioned motors. These motors not only have a simple and stable structure, but also production cost is low. In addition, these motors take advantage of great power, the ability to work in high speeds and inadequate environments (hot and dusty, reliability, control-ability, and high efficiency. However, discrete torque production of SRM along with enormous magnetic saturation in their cores reduces the variety of their industrial applications and also causes the inappropriate torque ripples. In this paper, a modified logical-rule-based method is proposed which employs the technique of controlling torque sharing function. Moreover, the optimized turn-on angle for conducting each phase is achieved by estimating the inductance curve in the vicinity of unaligned position and based on an analytical solution. Simulation results on a four-phase switched reluctance motor and a comparison with the conventional methods indicates validity and effectiveness of the proposed modified method.

  11. Closed-loop torque feedback for a universal field-oriented controller

    Science.gov (United States)

    De Doncker, R.W.A.A.; King, R.D.; Sanza, P.C.; Haefner, K.B.

    1992-11-24

    A torque feedback system is employed in a universal field-oriented (UFO) controller to tune a torque-producing current command and a slip frequency command in order to achieve robust torque control of an induction machine even in the event of current regulator errors and during transitions between pulse width modulated (PWM) and square wave modes of operation. 1 figure.

  12. Slip Torque Investigation and Magnetic Redesign of Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Frandsen, Tommy Vestergaard; Rasmussen, Peter Omand

    2015-01-01

    . Suspicion of the motor saturating before the MG reached peek torque and thus measuring the maximum torque of the motor instead, made the method questionable. The MIPMG has been modified to lock the HS side of the MG mechanically and new measurements have been conducted but with the same low slip torque...

  13. Torque expression of 0.018 and 0.022 inch conventional brackets

    NARCIS (Netherlands)

    Sifakakis, I.; Pandis, N.; Makou, M.; Eliades, T.; Katsaros, C.; Bourauel, C.

    2013-01-01

    The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond(R) Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch.

  14. The isometric torque at which knee-extensor muscle reoxygenation stops.

    NARCIS (Netherlands)

    de Ruiter, C.J.; Goudsmit, J.F.; Tricht, J.A.; de Haan, A.

    2007-01-01

    PURPOSE: We investigated the knee-extensor torque at which reoxygenation (inflow of arterial blood) during an isometric contraction stopped, whether this torque depended on maximal torque capacity (MTC), and whether there were differences among the synergists. METHODS: Isometric knee-extension

  15. Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Ritchie, Ewen

    2011-01-01

    The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....

  16. Artificial neural network based torque calculation of switched reluctance motor without locking the rotor

    Science.gov (United States)

    Kucuk, Fuat; Goto, Hiroki; Guo, Hai-Jiao; Ichinokura, Osamu

    2009-04-01

    Feedback of motor torque is required in most of switched reluctance (SR) motor applications in order to control torque and its ripple. An SR motor shows highly nonlinear property which does not allow calculating torque analytically. Torque can be directly measured by torque sensor, but it inevitably increases the cost and has to be properly mounted on the motor shaft. Instead of torque sensor, finite element analysis (FEA) may be employed for torque calculation. However, motor modeling and calculation takes relatively long time. The results of FEA may also differ from the actual results. The most convenient way seems to calculate torque from the measured values of rotor position, current, and flux linkage while locking the rotor at definite positions. However, this method needs an extra assembly to lock the rotor. In this study, a novel torque calculation based on artificial neural networks (ANNs) is presented. Magnetizing data are collected while a 6/4 SR motor is running. They need to be interpolated for torque calculation. ANN is very strong tool for data interpolation. ANN based torque estimation is verified on the 6/4 SR motor and is compared by FEA based torque estimation to show its validity.

  17. THE THYRISTOR CONVERTER INFLUENCE ON THE PULSATIONS OF THE ELECTROMAGNETIC TORQUE OF THE INDUCTION MOTOR AT PARAMETRICAL CONTROL

    Directory of Open Access Journals (Sweden)

    V. I. Lobov

    2017-08-01

    static and inertial moments. At the same time, it was revealed that the use of resistor-thyristor modules in the power circuits of the stator and rotary commutators reduces the magnitude of the pulsation of the electromagnetic torque of the induction electric motor. Increase the value of its maximum and average torques. Limit the magnitude of the shock and alternating torques when it starts and the transition from one speed to another. Scientific novelty. It is proposed to use a generalized circuit of parametric control of an induction electric motor for studying the change in the electromagnetic torque. The circuit consists of resistor – thyristor modules in stator and rotary commutators. The presented technique allowed simultaneously to investigate transients during the control of an induction electric motor by various power circuits of converters. The results of calculations allow choosing the necessary power circuit, taking into account the vibrational components of the electromagnetic torque of the induction motor.

  18. Alterations of the In Vivo Torque-Velocity Relationship of Human Skeletal Muscle Following 30 Days Exposure to Simulated Microgravity

    Science.gov (United States)

    Dudley, Gary A.; Duvoisin, Marc R.; Convertino, Victor A.; Buchanan, Paul

    1989-01-01

    The purpose of this study was to examine the effect of 30 d of 6 deg headdown bedrest (BR) on the in vivo strength of skeletal muscle. Peak angle specific (0.78 rad below horizontal) torque of the knee extensor (KE) and flexor (KF) muscle groups of both limbs was assessed during unilateral efforts at four speeds (0.52, 1.74, 2.97 and 4.19 rad/s) during concentric and at three speeds (0.52, 1.74 and 2.97 rad/s) during eccentric actions. The average decrease (P less than 0.05) of peak angle specific torque directly post-BR for the KE across speeds of concentric and eccentric actions was about 19% (n = 7). Recovery for 30 d following BR markedly improved strength to about 92% (P greater than 0.05) of 'normal'. Strength of the KF was not altered (P greater than 0.05) by BR (about a 6% decrease independent of speed and type of muscle action). Changes of strength were not affected by the type or speed of muscle action. The results indicate that strength of ex-tensor more than of flexor muscle groups of the lower limb is decreased by 30 d of bedrest and that this response does not alter the nature of the in vivo torque-velocity relation.

  19. Torque and Suspension Force in a Bearingless Switched Reluctance Motor

    Science.gov (United States)

    Takemoto, Masatsugu; Chiba, Akira; Akagi, Hirofumi; Fukao, Tadashi

    Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. The bearingless switched reluctance motors are characterized by integration of switched reluctance motors and magnetic bearings. These motors have two kinds of stator windings composed of motor main windings and suspension windings in the same stator in order to produce suspension force that can realize rotor shaft suspension without mechanical contacts or lubrication. For successful stable operation, accurate theoretical formulae of instantaneous torque and suspension force are necessary to a rotational speed controller and a rotor radial position controller. This paper derives the theoretical formulae of the instantaneous torque and the suspension force from an assumption of simple permeance distribution. This derivation process makes an assumption that fringing fluxes are distributed on elliptical lines. It is shown with experimental results that the derived theoretical formulae are very accurate in terms of practical application.

  20. Torque Control of Underactuated Tendon-driven Robotic Fingers

    Science.gov (United States)

    Abdallah, Muhammad E. (Inventor); Ihrke, Chris A. (Inventor); Reiland, Matthew J. (Inventor); Wampler, Charles W. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Bridgwater, Lyndon (Inventor)

    2013-01-01

    A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.

  1. Giant thermal spin-torque-assisted magnetic tunnel junction switching.

    Science.gov (United States)

    Pushp, Aakash; Phung, Timothy; Rettner, Charles; Hughes, Brian P; Yang, See-Hun; Parkin, Stuart S P

    2015-05-26

    Spin-polarized charge currents induce magnetic tunnel junction (MTJ) switching by virtue of spin-transfer torque (STT). Recently, by taking advantage of the spin-dependent thermoelectric properties of magnetic materials, novel means of generating spin currents from temperature gradients, and their associated thermal-spin torques (TSTs), have been proposed, but so far these TSTs have not been large enough to influence MTJ switching. Here we demonstrate significant TSTs in MTJs by generating large temperature gradients across ultrathin MgO tunnel barriers that considerably affect the switching fields of the MTJ. We attribute the origin of the TST to an asymmetry of the tunneling conductance across the zero-bias voltage of the MTJ. Remarkably, we estimate through magneto-Seebeck voltage measurements that the charge currents that would be generated due to the temperature gradient would give rise to STT that is a thousand times too small to account for the changes in switching fields that we observe.

  2. Impaired bed mobility: quantitative torque analysis with axial inertial sensors.

    Science.gov (United States)

    Bhidayasiri, Roongroj; Sringean, Jirada; Thanawattano, Chusak

    2017-08-01

    Difficulty in turning in bed is rated as the most troublesome night-time symptom among Parkinson's disease (PD) patients. To develop a practical objective method for home assessment of a patient's ability to turn in bed. Nocturnal parameters and torque of self-turning in bed from 17 PD couples were assessed and compared using a wearable axial sensor for two nights in their homes. The torque of axial rotation which indicates the ability of PD patients to turn in bed was significantly less than their spouses (p turning in bed and total unified Parkinson's Disease Rating Scale score (r = 0.71; p = 0.001), and total Nocturnal Akinesia Dystonia and Cramp score (r = 0.634; p = 0.006). Our study confirms a decreased ability in turning in PD.

  3. Spin Hall and spin swapping torques in diffusive ferromagnets

    KAUST Repository

    Pauyac, C. O.

    2017-12-08

    A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.

  4. Spin-Swapping Transport and Torques in Ultrathin Magnetic Bilayers

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2016-07-12

    Planar spin transport in disordered ultrathin magnetic bilayers comprising a ferromagnet and a normal metal (typically used for spin pumping, spin Seebeck and spin-orbit torque experiments) is investigated theoretically. Using a tight-binding model that puts the extrinsic spin Hall effect and spin swapping on equal footing, we show that the nature of spin-orbit coupled transport dramatically depends on the ratio between the layer thickness d and the mean free path λ. While the spin Hall effect dominates in the diffusive limit (d≫λ), spin swapping dominates in the Knudsen regime (d≲λ). A remarkable consequence is that spin swapping induces a substantial fieldlike torque in the Knudsen regime.

  5. Controlling the spin-torque efficiency with ferroelectric barriers

    KAUST Repository

    Useinov, A.

    2015-02-11

    Nonequilibrium spin-dependent transport in magnetic tunnel junctions comprising a ferroelectric barrier is theoretically investigated. The exact solutions of the free electron Schrödinger equation for electron tunneling in the presence of interfacial screening are obtained by combining Bessel and Airy functions. We demonstrate that the spin transfer torque efficiency, and more generally the bias dependence of tunneling magneto- and electroresistance, can be controlled by switching the ferroelectric polarization of the barrier. In particular, the critical voltage at which the in-plane torque changes sign can be strongly enhanced or reduced depending on the direction of the ferroelectric polarization of the barrier. This effect provides a supplementary way to electrically control the current-driven dynamic states of the magnetization and related magnetic noise in spin transfer devices.

  6. Torque magnetometry on thin magnetite films at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, R. E-mail: rhone@physik.uni-leipzig.de; Kleint, C.A.; Pan, A.V.; Krause, M.K.; Ziese, M.; Esquinazi, P

    2000-03-01

    Torque magnetometry was used to investigate the magnetic anisotropy of epitaxial Fe{sub 3}O{sub 4} films of thicknesses 420 and 40 nm grown by pulsed laser deposition on (0 0 1) MgO substrates. Torque measurements at 130 K in the (1 1-bar 0) plane allow us to evaluate the influence of shape and stress anisotropy. As in bulk material field-cooled measurements performed at T=5 K show that the magnetic anisotropy is strongly influenced by the direction of the magnetic field applied above the Verwey temperature. In contrast to bulk magnetite we find smaller effective contributions of the magneto-crystalline anisotropy. In zero-field-cooled films our measurements suggest a tendency to a preferential out-of-plane orientation of the magnetic easy axis, but the dominating shape anisotropy favours an in-plane orientation of the magnetization.

  7. Friction torque in thrust ball bearings grease lubricated

    Science.gov (United States)

    Ianuş, G.; Dumitraşcu, A. C.; Cârlescu, V.; Olaru, D. N.

    2016-08-01

    The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.

  8. The effect of accounting for biarticularity in hip flexor and hip extensor joint torque representations.

    Science.gov (United States)

    Lewis, M G C; Yeadon, M R; King, M A

    2018-02-01

    Subject-specific torque-driven models have ignored biarticular effects at the hip. The aim of this study was to establish the contribution of monoarticular hip flexors and hip extensors to total hip flexor and total hip extensor joint torques for an individual and to investigate whether torque-driven simulation models should consider incorporating biarticular effects at the hip joint. Maximum voluntary isometric and isovelocity hip flexion and hip extension joint torques were measured for a single participant together with surface electromyography. Single-joint and two-joint representations were fitted to the collected torque data and used to determine the maximum voluntary joint torque capacity. When comparing two-joint and single-joint representations, the single-joint representation had the capacity to produce larger maximum voluntary hip flexion torque (larger by around 9% of maximum torque) and smaller maximum voluntary hip extension torque (smaller by around 33% of maximum torque) with the knee extended. Considering the range of kinematics found for jumping movements, the single-joint hip flexors had the capacity to produce around 10% additional torque, while the single joint hip extensors had about 70% of the capacity of the two-joint representation. Two-joint representations may overcome an over-simplification of single-joint representations by accounting for biarticular effects, while building on the strength of determining subject-specific parameters from measurements on the participant. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Harmonic Analysis on Torque Ripple of Brushless DC Motor Based on Advanced Commutation Control

    Directory of Open Access Journals (Sweden)

    Yanpeng Ji

    2018-01-01

    Full Text Available This paper investigates the relationship between current, back electromotive force (back-EMF, and torque for permanent-magnet brushless DC (PM BLDC motors under advanced commutation control from the perspective of harmonics. Considering that the phase current is the influencing factor of both torque and torque ripple, this paper firstly analyzes the effects of advanced commutation on phase current and current harmonics. And then, based on the harmonics of the phase current and back-EMF, the torque harmonic expressions are deduced. The expressions reveal the relationship of harmonic order between the torque, phase current, and back-EMF and highlight the different contribution of individual torque harmonic to the total torque ripple. Finally, the proposed harmonic analysis method is verified by the experiments with different speed and load conditions.

  10. Direct relation of acute effects of static stretching on isokinetic torque production with initial flexibility level.

    Science.gov (United States)

    Babault, Nicolas; Bazine, Wacef; Deley, Gaëlle; Paizis, Christos; Lattier, Grégory

    2015-01-01

    To examine the acute effect of a single static-stretching session of hamstring muscles on torque production in relation with individual flexibility. Maximal voluntary concentric torque of hamstring muscles was measured before and after a static-stretching session (6 × 30 s). Torque changes were correlated with the flexibility level determined at the onset of the experimental procedure. The hamstring-stretching intervention significantly reduced maximal concentric torque in participants with low and high hamstring flexibility. Hamstring flexibility and torque decrease, determined immediately after the stretching procedure, were negatively correlated. Torque decrease measured after the static-stretching session is dependent on participant flexibility. Participants with low flexibility are much more likely to demonstrate large torque decreases poststretching.

  11. Four-bar linkage-based automatic tool changer: Dynamic modeling and torque optimization

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sangho; Seo, TaeWon [Yeungnam University, Gyeongsan (Korea, Republic of); Kim, Jong-Won; Kim, Jongwon [Seoul National University, Seoul (Korea, Republic of)

    2017-05-15

    An Automatic tool changer (ATC) is a device used in a tapping machine to reduce process time. This paper presents the optimization of a Peak torque reduction mechanism (PTRM) for an ATC. It is necessary to reduce the fatigue load and energy consumed, which is related to the peak torque. The PTRM uses a torsion spring to reduce the peak torque and was applied to a novel ATC mechanism, which was modeled using inverse dynamics. Optimization of the PTRM is required to minimize the peak torque. The design parameters are the initial angle and stiffness of the torsion spring, and the objective function is the peak torque of the input link. The torque was simulated, and the peak torque was decreased by 10 %. The energy consumed was reduced by the optimization.

  12. Muscle weakness, fatigue, and torque variability: effects of age and mobility status.

    Science.gov (United States)

    Kent-Braun, Jane A; Callahan, Damien M; Fay, Jessica L; Foulis, Stephen A; Buonaccorsi, John P

    2014-02-01

    Whereas deficits in muscle function, particularly power production, develop in old age and are risk factors for mobility impairment, a complete understanding of muscle fatigue during dynamic contractions is lacking. We tested hypotheses related to torque-producing capacity, fatigue resistance, and variability of torque production during repeated maximal contractions in healthy older, mobility-impaired older, and young women. Knee extensor fatigue (decline in torque) was measured during 4 min of dynamic contractions. Torque variability was characterized using a novel 4-component logistic regression model. Young women produced more torque at baseline and during the protocol than older women (P torque variability differed by group (P = 0.022) and was greater in older impaired compared with young women (P = 0.010). These results suggest that increased torque variability may combine with baseline muscle weakness to limit function, particularly in older adults with mobility impairments. Copyright © 2013 Wiley Periodicals, Inc.

  13. Improving the performance of hysteresis direct torque control of ...

    Indian Academy of Sciences (India)

    Lsd,Lsq – d-axis and q-axis stator inductances, p = d/dt – differential operator,. P – number of pole pairs of the motor, ωr – rotor speed,. F – rotor permanent magnetic flux,. eB = Pωr. F – is the generated back emf due to F ,. T e – generated electromagnetic torque. The proposed filter topology consists of three parts, one is the ...

  14. Solar Direct Torque Controlled Induction Motor Drive for Industrial Applications

    OpenAIRE

    PANDA, AUROBINDA; Pathak, Mukesh kumar; Srivastava, Satya Prakash

    2016-01-01

    With the continuous decrease of the cost of solar cells, there is an increasing interest in photovoltaic (PV) system applications. Electric motors powered by solar energy are one of the most important applications now-a-days, such as in water pumping systems, electric vehicles etc. This paper investigates a photovoltaic-electro mechanic chain, composed of a PV generator, an impedance adapter DC–DC converter, inverter and a direct torque controlled induction machine. The PV generator is forced...

  15. A Model of FPGA-based Direct Torque Controller

    OpenAIRE

    Auzani Jidin; Aiman Zakwan Jidin; Nik Rumzi Nik Idris; Tole Sutikno

    2013-01-01

    This paper presents a generic model of a fully FPGA-based direct torque controller. This model is developed using two’s-complement fixed-point format approaches, in register-transfer-level (RTL) VHDL abstraction for minimizing calculation errors and consuming hardware resource usage. Therefore, the model is universal and can be implemented for all FPGA types. The model is prepared for fast computation, without using of CORDIC algorithm, a soft-core CPU, a transformation from Cartesian-to-pola...

  16. Angular momentum and torque described with the complex octonion

    International Nuclear Information System (INIS)

    Weng, Zi-Hua

    2014-01-01

    The paper aims to adopt the complex octonion to formulate the angular momentum, torque, and force etc in the electromagnetic and gravitational fields. Applying the octonionic representation enables one single definition of angular momentum (or torque, force) to combine some physics contents, which were considered to be independent of each other in the past. J. C. Maxwell used simultaneously two methods, the vector terminology and quaternion analysis, to depict the electromagnetic theory. It motivates the paper to introduce the quaternion space into the field theory, describing the physical feature of electromagnetic and gravitational fields. The spaces of electromagnetic field and of gravitational field can be chosen as the quaternion spaces, while the coordinate component of quaternion space is able to be the complex number. The quaternion space of electromagnetic field is independent of that of gravitational field. These two quaternion spaces may compose one octonion space. Contrarily, one octonion space can be separated into two subspaces, the quaternion space and S-quaternion space. In the quaternion space, it is able to infer the field potential, field strength, field source, angular momentum, torque, and force etc in the gravitational field. In the S-quaternion space, it is capable of deducing the field potential, field strength, field source, current continuity equation, and electric (or magnetic) dipolar moment etc in the electromagnetic field. The results reveal that the quaternion space is appropriate to describe the gravitational features, including the torque, force, and mass continuity equation etc. The S-quaternion space is proper to depict the electromagnetic features, including the dipolar moment and current continuity equation etc. In case the field strength is weak enough, the force and the continuity equation etc can be respectively reduced to that in the classical field theory

  17. Neuromuscular fatigue following isometric contractions with similar torque time integral.

    Science.gov (United States)

    Rozand, V; Cattagni, T; Theurel, J; Martin, A; Lepers, R

    2015-01-01

    Torque time integral (TTI) is the combination of intensity and duration of a contraction. The aim of this study was to compare neuromuscular alterations following different isometric sub-maximal contractions of the knee extensor muscles but with similar TTI. Sixteen participants performed 3 sustained contractions at different intensities (25%, 50%, and 75% of Maximal Voluntary Contraction (MVC) torque) with different durations (68.5±33.4 s, 35.1±16.8 s and 24.8±12.9 s, respectively) but similar TTI value. MVC torque, maximal voluntary activation level (VAL), M-wave characteristics and potentiated doublet amplitude were assessed before and immediately after the sustained contractions. EMG activity of the vastus lateralis (VL) and -rectus femoris (RF) muscles was recorded during the sustained contractions. MVC torque reduction was similar in the 3 conditions after the exercise (-23.4±2.7%). VAL decreased significantly in a similar extent (-3.1±1.3%) after the 3 sustained contractions. Potentiated doublet amplitude was similarly reduced in the 3 conditions (-19.7±1.5%), but VL and RF M-wave amplitudes remained unchanged. EMG activity of VL and RF muscles increased in the same extent during the 3 contractions (VL: 54.5±40.4%; RF: 53.1±48.7%). These results suggest that central and peripheral alterations accounting for muscle fatigue are similar following isometric contractions with similar TTI. TTI should be considered in the exploration of muscle fatigue during sustained isometric contractions. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Optimal Control of an Electrical Drive System with Variable Torque

    Directory of Open Access Journals (Sweden)

    Corneliu Botan

    2014-09-01

    Full Text Available The optimal control from the energetic point of view of the transient state of electrical drive systems is presented. A step variation of the load torque in the optimization interval is considered. The performance criteria consider only Joule losses, since they significantly overcome other ones in the transient state. The paper refers to a structure with voltage control of the drive. The study is performed in continuous time domain for a fixed end point problem.

  19. PERANCANGAN TORQUE LIMITER CLUTCH PADA MESIN BODYMAKER AUTOMATIC WELDING

    Directory of Open Access Journals (Sweden)

    Daniel Dwiyanto

    2015-06-01

    Full Text Available Mesin bodymaker Automatic welding adalah mesin welding otomatis untuk pembuatan kaleng kemasan. Pada mesin mesin tertentu masih menggunakan system arus dalam memproteksi mesin terhadap overload yang terjadi. Namun pada praktek dilapangan system ini kurang maksimal dalam kinerjanya, jika mesin terjadi overload mesin tidak berhenti.Oleh karenanya perlu ditambahkan elemen mesin yang lain yang bisa secara otomatis menghentikan mesin saat overload terjadi. Berdasarkan hal tersebut diatas pada kesempatan ini saya ingin merancang torque limiter clutch. Dengan mengumpulkan data tentang spesifikasi motor penggerak utama maka akan dapat dirancang dan dihitung berapa dimensional komponen komponen, gaya maupun torsi yang bekerja, serta desain poros pada torque limiter clutch. Dengan perhitungan teoritis yang benar akan mendapatkan desain torque limiter clutch yang optimal, efisien sesuai dengan kapasitas mesin dikerjakan, kemudian proses perancangan dilanjutkan dalam bentuk gambar tehnik secara detail dan terperinci menggunakan software autocad 2007. Dari seluruh perhitungan perancangan diperoleh hasil bahwa mesin akan berhenti setelah overload terjadi pada 0,626 x 103 N.mm. Dalam proses kerjanya spring memegang peranan paling penting karena harus dapat  menahan ball agar tidak keluar dari lubang flange pada putaran normal dan membiarkan ball keluar dari lubang flange saat overload terjadi.

  20. Analytical Methods of Decoupling the Automotive Engine Torque Roll Axis

    Science.gov (United States)

    JEONG, TAESEOK; SINGH, RAJENDRA

    2000-06-01

    This paper analytically examines the multi-dimensional mounting schemes of an automotive engine-gearbox system when excited by oscillating torques. In particular, the issue of torque roll axis decoupling is analyzed in significant detail since it is poorly understood. New dynamic decoupling axioms are presented an d compared with the conventional elastic axis mounting and focalization methods. A linear time-invariant system assumption is made in addition to a proportionally damped system. Only rigid-body modes of the powertrain are considered and the chassis elements are assumed to be rigid. Several simplified physical systems are considered and new closed-form solutions for symmetric and asymmetric engine-mounting systems are developed. These clearly explain the design concepts for the 4-point mounting scheme. Our analytical solutions match with the existing design formulations that are only applicable to symmetric geometries. Spectra for all six rigid-body motions are predicted using the alternate decoupling methods and the closed-form solutions are verified. Also, our method is validated by comparing modal solutions with prior experimental and analytical studies. Parametric design studies are carried out to illustrate the methodology. Chief contributions of this research include the development of new or refined analytical models and closed-form solutions along with improved design strategies for the torque roll axis decoupling.

  1. Torque linearizing hardware for the electric joint motors of a direct-drive robot

    Science.gov (United States)

    Muir, P. F.; Bryan, J. R.

    Many emerging high-performance robot control algorithms require the command of the joint torques, yet no known commercial robots provide such a capability. We describe the design, development, testing, and application of a VMEbus-based torque linearizing joint interface board (JIB). One JIB resides between the robot control processor and each joint motor amplifier. The JIB provides the control processor with the capability to read the motor position and apply accurate motor torques. The torque command capability derives from the application of a 128k x 8 EPROM lookup table for each motor phase. Because joint motor torque is dependent upon the torque command and the motor position, the hardware is designed to utilize the torque command and the current motor position as the address to retrieve the proper pulse-width for the PWM motor amplifier. The table look-up cycle operates independently of the robot controller at a 40KHz rate to provide constant joint torque as the motor rotates. We identify the proper table entries by an automated in situ data collection procedure. Static torque generation results show that the torque deviations are reduced from as much as 76 percent to below 5 percent for each of the three direct-drive motors (two are variable reluctance motors and one is brushless DC) on an AdeptTwo robot. These torque deviations are reduced below 2.5 percent if only the upper 90 percent of the torque range is considered. The torque deviations of the non-direct-drive joint are reduced by 50 percent. Dynamic robot edge following experiments show that the robot speed of operation can be more than doubled for a given applied force accuracy by utilizing the joint torque linearizing boards.

  2. Reometria de torque, propriedades mecânicas e morfologia de blendas compatibilizadas de PA6/PEAD Torque rheometry, mechanical properties and morphology of compatibilized PA6/HDPE blends

    Directory of Open Access Journals (Sweden)

    Pankaj Agrawal

    2008-06-01

    shown that there was an increase in the torque of PA6/HDPE blend when the compatibilizers were added. PEgAA compatibilizer was more reactive with PA6 than the other compatibilizers. However, the torque decreased due to degradation. There was a substantial increase in impact strength of PA6/HDPE blend when the compatibilizers were added. These results were corroborated by the strain at break data. SEM results indicated that the addition of compatibilizers to PA6/PE blend has considerably decreased the HDPE average particles size and improved the adhesion between PA6 and HDPE phases, resulting in an increase in impact strength.

  3. Intrinsic and extrinsic spin-orbit torques from first principles

    International Nuclear Information System (INIS)

    Geranton, Guillaume

    2017-01-01

    This thesis attempts to shed light on the microscopic mechanisms underlying the current-induced magnetic torques in ferromagnetic heterostructures. We have developed first principles methods aiming at the accurate and effcient calculation of the so-called spin-orbit torques (SOTs) in magnetic thin films. The emphasis of this work is on the impurity-driven extrinsic SOTs. The main part of this thesis is dedicated to the development of a formalism for the calculation of the SOTs within the Korringa-Kohn-Rostoker (KKR) method. The impurity-induced transitions rates are obtained from first principles and their effect on transport properties is treated within the Boltzmann formalism. The developed formalism provides a mean to compute the SOTs beyond the conventional constant relaxation time approximation. We first apply our formalism to the investigation of FePt/Pt and Co/Cu bilayers in the presence of defects and impurities. Our results hint at a crucial dependence of the torque on the type of disorder present in the films, which we explain by a complex interplay of several competing Fermi surface contributions to the SOT. Astonishingly, specific defect distributions or doping elements lead respectively to an increase or a sign change of the torque, which can not be explained on the basis of simple models. We also compute the intrinsic SOT induced by electrical and thermal currents within the full potential linearized augmented plane-wave method. Motivated by recent experimental works, we then investigate the microscopic origin of the SOT in a Ag 2 Bi-terminated Ag film grown on ferromagnetic Fe(110). We find that the torque in that system can not be explained solely by the spin-orbit coupling in the Ag 2 Bi alloy, and instead results from the spin-orbit coupling in all regions of the film.Finally, we predict a large SOT in Fe/Ge bilayers and suggest that semiconductor substrates might be a promising alternative to heavy metals for the development of SOT-based magnetic

  4. A comparison of screw insertion torque and pullout strength.

    Science.gov (United States)

    Ricci, William M; Tornetta, Paul; Petteys, Timothy; Gerlach, Darin; Cartner, Jacob; Walker, Zakiyyah; Russell, Thomas A

    2010-06-01

    Pullout strength of screws is a parameter used to evaluate plate screw fixation strength. However, screw fixation strength may be more closely related to its ability to generate sufficient insertion because stable nonlocked plate-screw fracture fixation requires sufficient compression between plate and bone such that no motion occurs between the plate and bone under physiological loads. Compression is generated by tightening of screws. In osteoporotic cancellous bone, sufficient screw insertion torque may not be generated before screw stripping. The effect of screw thread pitch on generation of maximum insertion torque (MIT) and pullout strength (POS) was investigated in an osteoporotic cancellous bone model and the relationship between MIT and POS was analyzed. Stainless steel screws with constant major (5.0 mm) and minor (2.7 mm) diameters but with varying thread pitches (1, 1.2, 1.5, 1.6, and 1.75 mm) were tested for MIT and POS in a validated osteoporotic surrogate for cancellous bone (density of 160 kg/m(3) [10 lbs/ft(3)]). MIT was measured with a torque-measuring hex driver for screws inserted through a one-third tubular plate. POS was measured after insertion of screws to a depth of 20 mm based on the Standard Specification and Test Methods for Metallic Medical Bone Screws (ASTM F 543-07). Five screws were tested for each failure mode and screw design. The relationship between MIT and compressive force between the plate and bone surrogate was evaluated using pressure-sensitive film. There was a significant difference in mean MIT based on screw pitch (P compression between the plate and bone surrogate was found for increasing screw torque (R(2) = 0.97). These results indicate that the ability of different screw designs to generate high screw insertion torque in a model of osteoporotic cancellous bone is unrelated to their pullout strength. Therefore, extrapolation of results for POS to identify optimal screw design for osteoporotic bone may not be valid

  5. Intrinsic and extrinsic spin-orbit torques from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Geranton, Guillaume

    2017-09-01

    This thesis attempts to shed light on the microscopic mechanisms underlying the current-induced magnetic torques in ferromagnetic heterostructures. We have developed first principles methods aiming at the accurate and effcient calculation of the so-called spin-orbit torques (SOTs) in magnetic thin films. The emphasis of this work is on the impurity-driven extrinsic SOTs. The main part of this thesis is dedicated to the development of a formalism for the calculation of the SOTs within the Korringa-Kohn-Rostoker (KKR) method. The impurity-induced transitions rates are obtained from first principles and their effect on transport properties is treated within the Boltzmann formalism. The developed formalism provides a mean to compute the SOTs beyond the conventional constant relaxation time approximation. We first apply our formalism to the investigation of FePt/Pt and Co/Cu bilayers in the presence of defects and impurities. Our results hint at a crucial dependence of the torque on the type of disorder present in the films, which we explain by a complex interplay of several competing Fermi surface contributions to the SOT. Astonishingly, specific defect distributions or doping elements lead respectively to an increase or a sign change of the torque, which can not be explained on the basis of simple models. We also compute the intrinsic SOT induced by electrical and thermal currents within the full potential linearized augmented plane-wave method. Motivated by recent experimental works, we then investigate the microscopic origin of the SOT in a Ag{sub 2}Bi-terminated Ag film grown on ferromagnetic Fe(110). We find that the torque in that system can not be explained solely by the spin-orbit coupling in the Ag{sub 2}Bi alloy, and instead results from the spin-orbit coupling in all regions of the film.Finally, we predict a large SOT in Fe/Ge bilayers and suggest that semiconductor substrates might be a promising alternative to heavy metals for the development of SOT

  6. PREFACE: The Science of Making Torque from Wind

    Science.gov (United States)

    Sørensen, Jens N.; Hansen, Martin O. L.; Hansen, Kurt S.

    2007-06-01

    Wind energy has for many years been the fastest developing energy source. This is most easily demonstrated by some numbers. In 2006 a total of about 7.6 GW of new wind energy capacity was installed in Europe, an increase of more than 20% over the year before. Europe's cumulative wind power capacity has now reached more than 50 GW. At the beginning of 2007, the European Commission published its new energy strategy, which recommends a 20% target for the share of renewable energy in the EU by 2020. New initiatives have also been launched in the U.S. and Asia to comply with the need for a reduction in the emissions of CO2 and to create a cleaner environment based on renewable energy. Since 1980 the average size of wind turbines has grown by a factor of 100 from 50 kW to today's 5 MW machines. This enormous increase in size would not have been possible without the involvement of well-educated engineers and scientists. Research institutions and universities have contributed significantly to this development by providing basic knowledge as well as sophisticated software and measuring campaigns. In order to comply with the fast development in wind turbine technology there is a growing need for both well-educated scientists and for a further development of sophisticated predictive tools. For many years progress in technology development was presented at the European Wind Energy Conference (EWEC) conference organized by the European Wind Energy Association (EWEA). Because of the maturity of the industry and the many important topics involved in the continued development of wind power, the relative share of the technical and scientific sessions at EWEC has decreased dramatically. Hence it was desirable to find an alternative forum for the exchange of ideas and techniques within more specialized topics. As a consequence the European Academy of Wind Energy (EAWE) was created in 2003 in order to support education and research. It is the intention of this special topics

  7. Intramuscular Pressure of Tibialis Anterior Reflects Ankle Torque but Does Not Follow Joint Angle-Torque Relationship

    Directory of Open Access Journals (Sweden)

    Filiz Ateş

    2018-01-01

    Full Text Available Intramuscular pressure (IMP is the hydrostatic fluid pressure that is directly related to muscle force production. Electromechanical delay (EMD provides a link between mechanical and electrophysiological quantities and IMP has potential to detect local electromechanical changes. The goal of this study was to assess the relationship of IMP with the mechanical and electrical characteristics of the tibialis anterior muscle (TA activity at different ankle positions. We hypothesized that (1 the TA IMP and the surface EMG (sEMG and fine-wire EMG (fwEMG correlate to ankle joint torque, (2 the isometric force of TA increases at increased muscle lengths, which were imposed by a change in ankle angle and IMP follows the length-tension relationship characteristics, and (3 the electromechanical delay (EMD is greater than the EMD of IMP during isometric contractions. Fourteen healthy adults [7 female; mean (SD age = 26.9 (4.2 years old with 25.9 (5.5 kg/m2 body mass index] performed (i three isometric dorsiflexion (DF maximum voluntary contraction (MVC and (ii three isometric DF ramp contractions from 0 to 80% MVC at rate of 15% MVC/second at DF, Neutral, and plantarflexion (PF positions. Ankle torque, IMP, TA fwEMG, and TA sEMG were measured simultaneously. The IMP, fwEMG, and sEMG were significantly correlated to the ankle torque during ramp contractions at each ankle position tested. This suggests that IMP captures in vivo mechanical properties of active muscles. The ankle torque changed significantly at different ankle positions however, the IMP did not reflect the change. This is explained with the opposing effects of higher compartmental pressure at DF in contrast to the increased force at PF position. Additionally, the onset of IMP activity is found to be significantly earlier than the onset of force which indicates that IMP can be designed to detect muscular changes in the course of neuromuscular diseases impairing electromechanical transmission.

  8. Site Averaged Neutron Soil Moisture: 1988 (Betts)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Site averaged product of the neutron probe soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged...

  9. Site Averaged Gravimetric Soil Moisture: 1989 (Betts)

    Data.gov (United States)

    National Aeronautics and Space Administration — Site averaged product of the gravimetric soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each...

  10. Site Averaged Gravimetric Soil Moisture: 1988 (Betts)

    Data.gov (United States)

    National Aeronautics and Space Administration — Site averaged product of the gravimetric soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each...

  11. Site Averaged Gravimetric Soil Moisture: 1987 (Betts)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Site averaged product of the gravimetric soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged...

  12. Site Averaged Gravimetric Soil Moisture: 1987 (Betts)

    Data.gov (United States)

    National Aeronautics and Space Administration — Site averaged product of the gravimetric soil moisture collected during the 1987-1989 FIFE experiment. Samples were averaged for each site, then averaged for each...

  13. Acute effects of whole-body vibration on peak isometric torque, muscle twitch torque and voluntary muscle activation of the knee extensors.

    Science.gov (United States)

    Jordan, M; Norris, S; Smith, D; Herzog, W

    2010-06-01

    The purpose of this investigation was to compare the acute effects of whole-body vibration (WBV) with a static squat on resting muscle twitch torque, peak isometric torque and voluntary muscle activation of the knee extensors during an isometric maximal voluntary contraction (MVC). Twenty-four healthy, strength-trained males were recruited for this randomized, cross-over design investigation. The WBV treatment consisted of three sets of 60 s of vibration (30 Hz, +/-4 mm) while standing in a semi-squat position. Voluntary muscle activation, peak isometric torque during MVC and resting muscle twitch torque (RTT) through percutaneous femoral nerve stimulation were obtained before and following the treatment. Change in peak isometric torque, voluntary muscle activation and the RTT were calculated as the difference between pre- and post-treatment values. There was no observable post-activation potentiation of muscle twitch torque or enhancement in voluntary muscle activation or peak isometric torque. However, decreases in the peak isometric torque (P=0.0094) and voluntary muscle activation (P=0.0252) were significantly smaller post WBV interventions compared with the control treatment. Based on the current data, it is unclear whether or not this was attributable to the effects of WBV but further research into this possibility is warranted.

  14. Torque Ripple Suppression in an External-Meshed Magnetic Gear Train

    Directory of Open Access Journals (Sweden)

    Yi-Chang Wu

    2013-01-01

    Full Text Available Magnetic gear trains transmit torque through noncontact magnetic couplings rather than conjugate gear teeth; they have the unique advantages of reduced maintenance and improved reliability, inherent overload protection, high efficiency, precise peak torque transmission, and tolerance for misalignment. Smooth and steadily transmitted torque is an important characteristic for a magnetic gear train. It is necessary for the reduction of possible mechanical vibration, position inaccuracy, and acoustic noise. This paper investigates the transmitted torque characteristics, especially torque ripple reduction, of an external-meshed magnetic gear train using finite-element analysis (FEA. The topological structure and working principles of a simple magnetic gear train with parallel axes are introduced. With the aid of a commercial FEA package, the transmitted torque waveform of a magnetic gear train is numerically calculated. The effects of geometrical parameters on the maximum transmitted torque and torque ripple are further discussed in terms of obtaining a magnetic gear train with high transmitted torque or low torque ripple. This examination offers insights beneficial to future magnetic gear mechanism design.

  15. Multilevel Models for the Analysis of Angle-Specific Torque Curves with Application to Master Athletes

    Directory of Open Access Journals (Sweden)

    Carvalho Humberto M.

    2015-12-01

    Full Text Available The aim of this paper was to outline a multilevel modeling approach to fit individual angle-specific torque curves describing concentric knee extension and flexion isokinetic muscular actions in Master athletes. The potential of the analytical approach to examine between individual differences across the angle-specific torque curves was illustrated including between-individuals variation due to gender differences at a higher level. Torques in concentric muscular actions of knee extension and knee extension at 60°·s-1 were considered within a range of motion between 5°and 85° (only torques “truly” isokinetic. Multilevel time series models with autoregressive covariance structures with standard multilevel models were superior fits compared with standard multilevel models for repeated measures to fit anglespecific torque curves. Third and fourth order polynomial models were the best fits to describe angle-specific torque curves of isokinetic knee flexion and extension concentric actions, respectively. The fixed exponents allow interpretations for initial acceleration, the angle at peak torque and the decrement of torque after peak torque. Also, the multilevel models were flexible to illustrate the influence of gender differences on the shape of torque throughout the range of motion and in the shape of the curves. The presented multilevel regression models may afford a general framework to examine angle-specific moment curves by isokinetic dynamometry, and add to the understanding mechanisms of strength development, particularly the force-length relationship, both related to performance and injury prevention.

  16. Pelvic rotation torque during fast-pitch softball hitting under three ball height conditions.

    Science.gov (United States)

    Iino, Yoichi; Fukushima, Atsushi; Kojima, Takeji

    2014-08-01

    The purpose of this study was to investigate the relevance of hip joint angles to the production of the pelvic rotation torque in fast-pitch softball hitting and to examine the effect of ball height on this production. Thirteen advanced female softball players hit stationary balls at three different heights: high, middle, and low. The pelvic rotation torque, defined as the torque acting on the pelvis through the hip joints about the pelvic superior-inferior axis, was determined from the kinematic and force plate data using inverse dynamics. Irrespective of the ball heights, the rear hip extension, rear hip external rotation, front hip adduction, and front hip flexion torques contributed to the production of pelvic rotation torque. Although the contributions of the adduction and external rotation torques at each hip joint were significantly different among the ball heights, the contributions of the front and rear hip joint torques were similar among the three ball heights owing to cancelation of the two torque components. The timings of the peaks of the hip joint torque components were significantly different, suggesting that softball hitters may need to adjust the timings of the torque exertions fairly precisely to rotate the upper body effectively.

  17. Multilevel Models for the Analysis of Angle-Specific Torque Curves with Application to Master Athletes

    Science.gov (United States)

    Carvalho, Humberto M

    2015-01-01

    The aim of this paper was to outline a multilevel modeling approach to fit individual angle-specific torque curves describing concentric knee extension and flexion isokinetic muscular actions in Master athletes. The potential of the analytical approach to examine between individual differences across the angle-specific torque curves was illustrated including between-individuals variation due to gender differences at a higher level. Torques in concentric muscular actions of knee extension and knee extension at 60º·s−1 were considered within a range of motion between 5º and 85º (only torques “truly” isokinetic). Multilevel time series models with autoregressive covariance structures with standard multilevel models were superior fits compared with standard multilevel models for repeated measures to fit angle-specific torque curves. Third and fourth order polynomial models were the best fits to describe angle-specific torque curves of isokinetic knee flexion and extension concentric actions, respectively. The fixed exponents allow interpretations for initial acceleration, the angle at peak torque and the decrement of torque after peak torque. Also, the multilevel models were flexible to illustrate the influence of gender differences on the shape of torque throughout the range of motion and in the shape of the curves. The presented multilevel regression models may afford a general framework to examine angle-specific moment curves by isokinetic dynamometry, and add to the understanding mechanisms of strength development, particularly the force-length relationship, both related to performance and injury prevention. PMID:26839603

  18. Immediate effects of whole body vibration on patellar tendon properties and knee extension torque.

    Science.gov (United States)

    Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R

    2016-03-01

    Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length. Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling. The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°. The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.

  19. Joint torque and angle estimation by using ultrasonic muscle activity sensor

    Science.gov (United States)

    Tsutsui, Yoichiro; Tanaka, Takayuki; Kaneko, Shun'ichi; Feng, Maria Q.

    2005-12-01

    We have proposed a brand-new noninvasive ultrasonic sensor for measuring muscle activities named as Ultrasonic Muscle Activity Sensor (UMS). In the previous paper, the authors achieved to accurately estimate joint torque by using UMS and electromyogram (EMG) which is one of the most popular sensors. This paper aims to realize to measure not only joint torque also joint angle by using UMS and EMG. In order to estimate torque and angle of a knee joint, muscle activities of quadriceps femoris and biceps femoris were measured by both UMS and EMG. These targeted muscles are related to contraction and extension of knee joint. Simultaneously, actual torque on the knee joint caused by these muscles was measured by using torque sensor. The knee joint angle was fixed by torque sensor in the experiment, therefore the measurement was in isometric state. In the result, we found that the estimated torque and angle have high correlation coefficient to actual torque and angle. This means that the sensor can be used for angle estimation as well torque estimation. Therefore, it is shown that the combined use of UMS and EMG is effective to torque and angle estimation.

  20. Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production.

    Science.gov (United States)

    Noorkõiv, Marika; Nosaka, Kazunori; Blazevich, Anthony J

    2015-01-01

    This study aims to (1) determine whether isometric training at a short vs. long quadriceps muscle length affects concentric torque production; (2) examine the relationship between muscle hypertrophy and concentric torque; and (3) determine whether changes in fascicle length are associated with changes in concentric torque. Sixteen men performed isometric training at a short (SL, n = 8) or a long muscle length (LL, n = 8). Changes in maximal concentric torque were measured at 30, 60, 90, 120, 180, 240 and 300 rad · s(-1). The relationships between the changes in concentric torque, cross-sectional area, volume and fascicle length were tested. Concentric torque increased significantly after training only in LL and at angular velocities of 30 and 120 rad · s(-1) by 12-13% (P Muscle size increased in LL only, the changes were correlated (r = 0.73-0.93, P torque. Vastus lateralis (VL) fascicle length increased in both groups (5.4 ± 4.9%, P = 0.001) but the change was not correlated with changes in concentric torque in either group. Isometric training-induced increases in muscle size and concentric torque were best elicited by training at long muscle lengths. These results highlight a clear muscle length dependence of isometric training on dynamic torque production.

  1. How Joint Torques Affect Hamstring Injury Risk in Sprinting Swing–Stance Transition

    Science.gov (United States)

    SUN, YULIANG; WEI, SHUTAO; ZHONG, YUNJIAN; FU, WEIJIE; LI, LI; LIU, YU

    2015-01-01

    ABSTRACT Purpose The potential mechanisms of hamstring strain injuries in athletes are not well understood. The study, therefore, was aimed at understanding hamstring mechanics by studying loading conditions during maximum-effort overground sprinting. Methods Three-dimensional kinematics and ground reaction force data were collected from eight elite male sprinters sprinting at their maximum effort. Maximal isometric torques of the hip and knee were also collected. Data from the sprinting gait cycle were analyzed via an intersegmental dynamics approach, and the different joint torque components were calculated. Results During the initial stance phase, the ground reaction force passed anteriorly to the knee and hip, producing an extension torque at the knee and a flexion torque at the hip joint. Thus, the active muscle torque functioned to produce flexion torque at the knee and extension torque at the hip. The maximal muscle torque at the knee joint was 1.4 times the maximal isometric knee flexion torque. During the late swing phase, the muscle torque counterbalanced the motion-dependent torque and acted to flex the knee joint and extend the hip joint. The loading conditions on the hamstring muscles were similar to those of the initial stance phase. Conclusions During both the initial stance and late swing phases, the large passive torques at both the knee and hip joints acted to lengthen the hamstring muscles. The active muscle torques generated mainly by the hamstrings functioned to counteract those passive effects. As a result, during sprinting or high-speed locomotion, the hamstring muscles may be more susceptible to high risk of strain injury during these two phases. PMID:24911288

  2. Weighted south-wide average pulpwood prices

    Science.gov (United States)

    James E. Granskog; Kevin D. Growther

    1991-01-01

    Weighted average prices provide a more accurate representation of regional pulpwood price trends when production volumes valy widely by state. Unweighted South-wide average delivered prices for pulpwood, as reported by Timber Mart-South, were compared to average annual prices weighted by each state's pulpwood production from 1977 to 1986. Weighted average prices...

  3. Averaging of nonlinearity-managed pulses

    International Nuclear Information System (INIS)

    Zharnitsky, Vadim; Pelinovsky, Dmitry

    2005-01-01

    We consider the nonlinear Schroedinger equation with the nonlinearity management which describes Bose-Einstein condensates under Feshbach resonance. By using an averaging theory, we derive the Hamiltonian averaged equation and compare it with other averaging methods developed for this problem. The averaged equation is used for analytical approximations of nonlinearity-managed solitons

  4. Torque and pressure fluctuations in turbulent von Karman swirling flow between two counter-rotating disks. I

    Science.gov (United States)

    Burnishev, Yuri; Steinberg, Victor

    2014-05-01

    We report the experimental studies of the statistical and scaling properties of the fully developed turbulent regime in von Karman swirling flow between counter-rotating disks with and without blades using the only global measurements of the spatially averaged torque Γ and pressure p fluctuations in water and water-sugar solutions of different viscosities in the same cell geometry. We show that for all fluids under investigation probability distribution functions (PDFs) of the torque fluctuations δΓ/Γrms are Gaussian in both the laminar and turbulent regimes and for the both types of the stirrers. On the contrary, PDFs of the pressure fluctuations change from Gaussian in the laminar regime into the skewed shape with the exponential tails toward low-pressure events for both the entrainment methods. Both the friction coefficient Cf and normalized rms of the pressure fluctuations Cp are independent of Re in the fully developed turbulent regime for all fluids under study and found in a good quantitative agreement with the previous results. We also observe that the internal flow variables such as the normalized torque bar{Γ }/Vp_{rms} versus the "internal" Reynolds number Rerms = (prms/ρ)1/2Rρ/η instead of the global variables Cf, Cp versus Re show sharp transition into the well developed turbulent regime. We find that the scaling exponents of the fundamental characteristics based only on Γ and p measurements in the range of fully developed turbulent flow, namely, the integral, Taylor, and Kolmogorov dissipation lengths, as well as the Taylor-based Reynolds number Rλ, are in rather fair agreement with the predictions. We would like to emphasize that scaling of the main turbulent parameters Rλ, λ, ηd obtained via the global variables is a very non-trivial result. It is not obvious that measurements based on the global quantities will provide the predicted scaling relations. The result on such scaling obtained previously strongly disagrees with the scaling

  5. Correlation between ISQ and Insertion Torque values using double acid-etched implants

    Directory of Open Access Journals (Sweden)

    Sebastián Gallardo

    2016-12-01

    Full Text Available Aim The purpose of this study was threefold: (1 to consider whether there was a correlation between stability quotient values (ISQ and insertion torque values (IT at implant placement (2; to determine which of these values were more related to success or failure; and (3 to determine the influence of bone type and implant length, diameter and shape in the study results. Materials and methods A retrospective clinical study was carried out between June 2012 and June 2014. The insertion torque and resonance frequency values of 279 double achid etched implants (Osseotite, Biomet 3i, Implant Innovations Inc., Palm Beach Gardens, USA, with conical and parallel walls, and of different diameters and lengths, were tested at the moment of insertion in 90 patients of different age (18-82 years of age/ average: 60.89 years and of both genders (58 females and 32 males. Collected data were processed and subjected to statistical analysis. Results The mean ISQ value was 70.54, showing no statistical significance between successful and unsuccessful implants. The mean IT value was 44.18. In this case, the values obtained showed a difference between successful and unsuccessful implants, yet not statistically significant (p> 0.05. However, statistically significant differences were found in relation to bone type, shape and length of the implants in IT as well as ISQ values. In the former case (IT values, the differences were only related to diameter. Conclusion There was a correlation between ISQ and IT values; with no significant difference concerning success or failure. The variables analyzed showed statistical differences, except for diameter, which was only significant for IT.

  6. Novel compact model for multi-level spin torque magnetic tunnel junctions

    Science.gov (United States)

    Prajapati, Sanjay; Verma, Shivam; Kulkarni, Anant Aravind; Kaushik, Brajesh Kumar

    2016-10-01

    Spin-transfer torque (STT) and spin-orbit torque (SOT) based magnetic tunnel junction (MTJ) devices are emerging as strong contenders for the next generation memories. Conventional STT magneto-resistive random access memory (MRAM) offers lower power, non-volatility and CMOS process compatibility. However, higher current requirement during the write operation leads to tunnel barrier reliability issues and larger access devices. SOT-MRAM eliminates the reliability issues with strong spin polarized current (100%) and separate read/write current paths; however, the additional two access transistors in SOT-MRAM results into increased cell area. Multilevel cell (MLC) structure paves a way to circumvent the problems related to the conventional STT/SOT based MTJ devices and provides enhanced integration density at reduced cost per bit. Conventional STT/SOT-MRAM requires a unit cell area of 10-60 F2 and reported simulations have been based on available single-level MTJ compact models. However, till date no compact model exists that can capture the device physics of MLC-MTJ accurately. Hence, a novel compact model is proposed in this paper to capture the accurate device physics and behaviour of the MLC-MTJs. It is designed for MLCs with different MTJ configurations demonstrated so far, such as series and parallel free layer based MLC-MTJs. The proposed model is coded in Verilog-A, which is compatible with SPICE for circuit level simulations. The model is in close agreement with the experimental results exhibiting an average error of less than 15%.

  7. Condition monitoring of a motor-operated valve using estimated motor torque

    International Nuclear Information System (INIS)

    Chai, Jangbom; Kang, Shinchul; Park, Sungkeun; Hong, Sungyull; Lim, Chanwoo

    2004-01-01

    This paper is concerned with the development of data analysis methods to be used in on-line monitoring and diagnosis of Motor-Operated Valves (MOVs) effectively and accurately. The technique to be utilized includes the electrical measurements and signal processing to estimate electric torque of induction motors, which are attached to most of MOV systems. The estimated torque of an induction motor is compared with the directly measured torque using a torque cell in various loading conditions including the degraded voltage conditions to validate the estimating scheme. The accuracy of the estimating scheme is presented. The advantages of the estimated torque signatures are reviewed over the currently used ones such as the current signature and the power signature in several respects: accuracy, sensitivity, resolution and so on. Additionally, the estimated torque methods are suggested as a good way to monitor the conditions of MOVs with higher accuracy. (author)

  8. Current induced torques and interfacial spin-orbit coupling: Semiclassical modeling

    KAUST Repository

    Haney, Paul M.

    2013-05-07

    In bilayer nanowires consisting of a ferromagnetic layer and a nonmagnetic layer with strong spin-orbit coupling, currents create torques on the magnetization beyond those found in simple ferromagnetic nanowires. The resulting magnetic dynamics appear to require torques that can be separated into two terms, dampinglike and fieldlike. The dampinglike torque is typically derived from models describing the bulk spin Hall effect and the spin transfer torque, and the fieldlike torque is typically derived from a Rashba model describing interfacial spin-orbit coupling. We derive a model based on the Boltzmann equation that unifies these approaches. We also consider an approximation to the Boltzmann equation, the drift-diffusion model, that qualitatively reproduces the behavior, but quantitatively differs in some regimes. We show that the Boltzmann equation with physically reasonable parameters can match the torques for any particular sample, but in some cases, it fails to describe the experimentally observed thickness dependencies.

  9. The Mechanism of Yaw Torque Compensation in the Human and Motion Design for Humanoid Robots

    Directory of Open Access Journals (Sweden)

    Si Zhang

    2013-01-01

    Full Text Available When a humanoid robot walks fast or runs, the yaw torque is so large that the supporting foot slips easily and the robot may become unstable. The compensation for the yaw torque is important for fast humanoid walking and many studies have been focusing on yaw torque compensation. However, the issue of humanoid robot motion design that can make the movements of the robot more human-like, as well as guarantee the stability of the robot, has not been studied in-depth. In this paper, the mechanism of yaw torque compensating for human walking is firstly studied. Then we propose a method to compensate yaw torque for a humanoid robot through the motion of the arms and waist joint based on the human yaw torque compensation mechanism and ZMP stability citation. Finally, the effectiveness of the proposed method is demonstrated by the results from the simulation and walking experiments on the newly developed BHR humanoid robot.

  10. Dynamic VM Provisioning for TORQUE in a Cloud Environment

    Science.gov (United States)

    Zhang, S.; Boland, L.; Coddington, P.; Sevior, M.

    2014-06-01

    Cloud computing, also known as an Infrastructure-as-a-Service (IaaS), is attracting more interest from the commercial and educational sectors as a way to provide cost-effective computational infrastructure. It is an ideal platform for researchers who must share common resources but need to be able to scale up to massive computational requirements for specific periods of time. This paper presents the tools and techniques developed to allow the open source TORQUE distributed resource manager and Maui cluster scheduler to dynamically integrate OpenStack cloud resources into existing high throughput computing clusters.

  11. Torque Ripple Suppression in an External-Meshed Magnetic Gear Train

    OpenAIRE

    Yi-Chang Wu; Wan-Tsun Tseng; Yueh-Tung Chen

    2013-01-01

    Magnetic gear trains transmit torque through noncontact magnetic couplings rather than conjugate gear teeth; they have the unique advantages of reduced maintenance and improved reliability, inherent overload protection, high efficiency, precise peak torque transmission, and tolerance for misalignment. Smooth and steadily transmitted torque is an important characteristic for a magnetic gear train. It is necessary for the reduction of possible mechanical vibration, position inaccuracy, and acou...

  12. Torque control of a separate excitation DC motor for a dynamometer

    OpenAIRE

    Derges, Jonathan R.

    2010-01-01

    Approved for public release; distribution is unlimited In this thesis, the theory behind a separate-winding excitation direct current (DC) motor and profile of the motor's torque versus rotor speed is studied. The torque versus rotor speed profile results are predictably linear at a given armature voltage. Output torque of a separate-winding excitation DC motor is proportional to the armature current. From this theory, a program was written in Simulink with Xilinx embedded software to enab...

  13. Harmonic Analysis on Torque Ripple of Brushless DC Motor Based on Advanced Commutation Control

    OpenAIRE

    Ji, Yanpeng; Li, Bin; Sun, Jingcheng

    2018-01-01

    This paper investigates the relationship between current, back electromotive force (back-EMF), and torque for permanent-magnet brushless DC (PM BLDC) motors under advanced commutation control from the perspective of harmonics. Considering that the phase current is the influencing factor of both torque and torque ripple, this paper firstly analyzes the effects of advanced commutation on phase current and current harmonics. And then, based on the harmonics of the phase current and back-EMF, the...

  14. Calculation of electromagnetic torque for synchronous motor with modulated magnetic flux and smooth harmonic rotor

    Science.gov (United States)

    Shevchenko, A. F.; Shevchenko, L. G.

    2017-10-01

    Results of the electromagnetic torque calculation for the synchronous motor with modulated magnetic flux and a smooth harmonic rotor are presented in this paper. The value of the torque is determined from the electromagnetic forces, which appear due to interaction of magnetic field in the gap with the rotor surface elements. The obtained analytical expression makes it possible to determine easily the electromagnetic torque for the considered motor in the MathCAD environment.

  15. Implementation of the Direct Torque Control (DTC) in current model, with current starting limiter

    OpenAIRE

    Mino Aguilar, Gerardo; Muñoz Hernández, German Ardul; Romeral Martínez, José Luis; Cortez, Liliana; Saynes Torres, J.

    2012-01-01

    This paper presents the scheme of Direct Torque Control (DTC) for induction motor drives, where flux and torque of the motor are estimated by the IM current model. Its scheme requires the knowledge of speed, rotor time constant and inductive parameters of the motor. The results prove the excellent characteristics for torque response and efficiency, which confirm the validity of this control scheme. Due to the rapid response offered by the DTC, this causes a high star current inversor protecti...

  16. Analysis of reaction torque-based control of a redundant free-floating space robot

    Directory of Open Access Journals (Sweden)

    Minghe JIN

    2017-10-01

    Full Text Available Owing to the dynamics coupling between a free-floating base and a manipulator, the non-stationary base of a space robot will face the issue of base disturbance due to a manipulator’s motion. The reaction torque acted on the satellite base’s centroid is an important index to measure the satellite base’s disturbance. In this paper, a comprehensive analysis of the reaction torque is made, and a novel way to derive the analytical form of the reaction torque is proposed. In addition, the reaction torque null-space is derived, in which the manipulator’s joint motion is dynamically decoupled from the motion of the satellite base, and its novel expression demonstrates the equivalence between the reaction torque null-space and the reaction null-space. Furthermore, the reaction torque acted as an optimization index can be utilized to achieve satellite base disturbance minimization in the generalized Jacobian-based end-effector Cartesian path tracking task. Besides, supposing that the redundant degrees of freedom are abundant to achieve reaction torque-based active control, the reaction torque can be used to realize satellite base attitude control, that is, base attitude adjustment or maintenance. Moreover, because reaction torque-based control is a second-order control scheme, joint torque minimization can be regarded as the optimization task in reaction torque-based active or in-active control. A real-time simulation system of a 7-DOF space robot under Linux/RTAI is developed to verify and test the feasibility and reliability of the proposed ideas. Our extensive empirical results demonstrate that the corresponding analysis about the reaction torque is correct and the proposed methods are feasible.

  17. Using GMDH Neural Networks to Model the Power and Torque of a Stirling Engine

    OpenAIRE

    Ahmadi, Mohammad; Ahmadi, Mohammad-Ali; Mehrpooya, Mehdi; Rosen, Marc

    2015-01-01

    Different variables affect the performance of the Stirling engine and are considered in optimization and designing activities. Among these factors, torque and power have the greatest effect on the robustness of the Stirling engine, so they need to be determined with low uncertainty and high precision. In this article, the distribution of torque and power are determined using experimental data. Specifically, a novel polynomial approach is proposed to specify torque and power, on the basis of p...

  18. Sensorless sliding mode torque control of an IPMSM drive based on active flux concept

    OpenAIRE

    Hassan, A.A.; El-Sawy, A.M.; Mohamed, Y.S.; Shehata, E.G.

    2012-01-01

    This paper investigates a novel direct torque control of a sensorless interior permanent magnet synchronous motor based on a sliding mode technique. The speed and position of the interior permanent magnet synchronous motor are estimated online based on active flux concept. To overcome the large ripple content associated with the direct torque, a torque/flux sliding mode controller has been employed. Two integral surface functions are used to construct the sliding mode controller. The command ...

  19. Observerless Scheme for Sensorless Speed Control of PMSM Using Direct Torque Control Method With LP Filter

    OpenAIRE

    BEKIROGLU, N.; OZCIRA, S.

    2010-01-01

    In this study, direct torque control (DTC) of a permanent magnet synchronous motor is realized with a sensorless speed control technique without using an observer. Space vector pulse width modulation (SVPWM) technique is applied in order to determine the switching sequence of the voltage source inverter. Torque and flux, the main variables of the DTC, are estimated by using the mathematical model of the motor. Estimated torque and flux values are compared with their references in every con...

  20. Frequency Properties Research of Elevator Drive System with Direct Torque Control-Pulse with Modulation

    Directory of Open Access Journals (Sweden)

    A. S. Koval

    2008-01-01

    Full Text Available In the article problems of frequency properties research for electric drive system with direct torque control and pulse width modulator are described. The mathematical description of elevator is present. Simplified mathematical description of direct torque control - pulse width modulator electric drive system is shown. Transfer functions for torque and speed loops are determined. Logarithmic frequency characteristics are computed. Damping properties of elevator drive system are estimated.

  1. Enhanced precision of ankle torque measure with an open-unit dynamometer mounted with a 3D force-torque sensor.

    Science.gov (United States)

    Toumi, A; Leteneur, S; Gillet, C; Debril, J-F; Decoufour, N; Barbier, F; Jakobi, J M; Simoneau-Buessinger, Emilie

    2015-11-01

    Many studies have focused on maximum torque exerted by ankle joint muscles during plantar flexion. While strength parameters are typically measured with isokinetic or isolated ankle dynamometers, these devices often present substantial limitations for the measurement of torque because they account for force in only 1 dimension (1D), and the device often constrains the body in a position that augments torque through counter movements. The purposes of this study were to determine the contribution of body position to ankle plantar-flexion torque and to assess the use of 1D and 3D torque sensors. A custom designed 'Booted, Open-Unit, Three dimension, Transportable, Ergometer' (B.O.T.T.E.) was used to quantify plantar flexion in two conditions: (1) when the participant was restrained within the unit (locked-unit) and (2) when the participant's position was independent of the ankle dynamometer (open-unit). Ten young males performed maximal voluntary isometric plantar-flexion contractions using the B.O.T.T.E. in open and locked-unit mechanical configurations. The B.O.T.T.E. was reliable with ICC higher than 0.90, and CV lower than 7 %. The plantar-flexion maximal resultant torque was significantly higher in the locked-unit compared with open-unit configuration (P torque sensor significantly underestimated the proper capacity of plantar-flexion torque production (P torque should be performed with an open-unit dynamometer mounted with a 3D sensor that is exclusive of accessory muscles but inclusive of all ankle joint movements.

  2. Muscle mass, isokinetic torque, and functional capacity in women with osteoarthritis of the knee.

    Science.gov (United States)

    Gür, Hakan; Cakin, Nilgün

    2003-10-01

    To investigate the relations between cross-sectional area and concentric and eccentric torques in the quadriceps and hamstring muscles and to determine how functional capacity relates to pain, muscle mass, and concentric and eccentric knee torques in women who have bilateral osteoarthritis (OA) of the knee. Randomized, descriptive study. A university exercise physiology laboratory in Turkey. Eighteen women with bilateral knee OA (grades 2 or 3) graded radiographically. Not applicable. Selected functional tests included the 15-m walk, rising from a chair, descending stairs, and stair climbing. Pain during the functional tests was subjectively measured on an 11-point scale (range, 0-10). Concentric and eccentric torques of the quadriceps and hamstring muscles were measured by isokinetic dynamometry with angular velocities of 60 degrees, 120 degrees, and 180 degrees /s; cross-sectional areas of the quadriceps and hamstring muscles were measured by computed tomography. Eccentric torque was significantly (P range, quadriceps (range, 16%-100%) and hamstring (range, 50%-158%) muscles at all angular velocities. Torque-velocity curves for concentric and eccentric contractions were almost identical to those found in healthy young and elderly people. According to r(2) values, cross-sectional area of the quadriceps and hamstring muscles explained 24% to 61% (r(2) range,.24-.61) and 38% to 51% (r(2) range,.38-.51) of the variations in concentric and eccentric peak torques, respectively. Very small to moderate correlations (.01-.75) were observed among torque at any velocity and the variables of functional capacity and pain. For stair-climbing times, the best predictor variable was the eccentric hamstring to concentric quadriceps torque ratio. For stair descending, it was the concentric hamstring to eccentric quadriceps torque ratios. These torque ratios explained 81% (r(2)=.81) and 61% (r(2)=.61) of the variations, respectively. The findings in a patient group with bilateral OA

  3. Detent torque from the soft magnetic stator stack of a hybrid stepper motor

    Science.gov (United States)

    Rajagopal, K. R.; Singh, Bhim; Singh, B. P.

    2003-05-01

    The residual magnetism present in the stator stack of a hybrid stepper motor, which will be of the last excited polarity, will develop a detent torque, similar to the static torque of the last excited phase, but with reduced excitation. The predominant component is fundamental. Even though this torque is the result of the stator excitation, it can be considered as a detent torque as it is available when the stator excitation is withdrawn. This detent torque is in addition to the inherent one due to the rotor permanent magnet, and it will be present until the next phase is switched ON. Once the excitation is removed from the second phase, because of the hysteresis the detent torque will be available, similar to the static torque profile for phase 2, but with less excitation. This means because of the hysteresis the detent torque follows the static torque of the phases. The magnitude of this detent torque will depend upon the level to which the phase was excited. Experiments have been carried out on a 0.5° hybrid stepper motor to study the effects of the excitation on the detent torque profiles. Harmonic analyses of the measured detent torque curves had been carried out and it is seen that the fundamental detent torque increases with the excitation and also follows the respective phases. Therefore, the residual flux density and the coercive force of the soft magnetic material used for the stator stack have to be as small as possible to get rid of this effect. Controlling a hybrid stepper motor by a suitable switching scheme for a given application requires the measured static torque profiles of the motor for all the phases at the exact working voltage (or voltages in case of a variable voltage supply) and detent torque profiles both before and after excitation. Harmonic spectrum of the measured static and detent torque profiles have to be accounted for while simulating stepping behavior of the motor, from which an appropriate switching scheme can be arrived at.

  4. Cost-Effective Shaft Torque Observer for Condition Monitoring of Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Kirkegaard, Poul Henning; Pedersen, Bo Juul

    2015-01-01

    failure mechanisms as well as provide a method for detecting mass imbalance and aerodynamic asymmetry. The major obstacle preventing the industrial application of CM based on the shaft torque signal is the costly measurement equipment which is impractical for long-term use on operating WTs. This paper...... implementation of the shaft torque estimator. Its performance is validated for a scenario where there are frequent changes of operating points. The proposed cost-effective shaft torque estimator overcomes all major problems, which prevent the industrial application of CM systems based on shaft torque...

  5. Design and control of the phase current of a brushless dc motor to eliminate cogging torque

    Science.gov (United States)

    Jang, G. H.; Lee, C. J.

    2006-04-01

    This paper presents a design and control method of the phase current to reduce the torque ripple of a brushless dc (BLDC) motor by eliminating cogging torque. The cogging torque is the main source of torque ripple and consequently of speed error, and it is also the excitation source to generate the vibration and noise of a motor. This research proposes a modified current wave form, which is composed of main and auxiliary currents. The former is the conventional current to generate the commutating torque. The latter generates the torque with the same magnitude and opposite sign of the corresponding cogging torque at the given position in order to eliminate the cogging torque. Time-stepping finite element method simulation considering pulse-width-modulation switching method has been performed to verify the effectiveness of the proposed method, and it shows that this proposed method reduces torque ripple by 36%. A digital-signal-processor-based controller is also developed to implement the proposed method, and it shows that this proposed method reduces the speed ripple significantly.

  6. Increase of economy of torque flow pump with high specific speed

    Science.gov (United States)

    Gusak, A. G.; Krishtop, I. V.; German, V. F.; Baga, V. N.

    2017-08-01

    Torque flow pumps are widely spread types of energy machines, which are used in majority of modern branches of industry for pumping of dirty media. The main task of researchers of torque flow pumps is increase of such pumps effectiveness for higher feed. Hydraulic losses for torque flow pumps are caused by working process of such pumps and are inevitable. Decrease of losses can be obtained by means of optimization of hydraulic flow part geometry. Modern approach to design of pump outlet introduces new constructive solutions which can increase economy of torque flow pumps. The aim of this research is increase of economy of torque flow pumps by means of application of spatial outlet and investigation of its geometry on pump characteristics. Analytical and numerical methods of liquid flow research for hydraulic flow part of torque flow pump were used in this paper. Moreover, influence of hydraulic flow part geometry of different designs of “Turo” type torque flow pumps outlets on pump characteristics was investigated. Numerical research enabled to study process of energy transfer of torque flow pump and evaluate influence of geometrical dimensions of spatial spiral outlet on its characteristics. Besides numerical research confirmed introduced regularity of peripheral velocity distribution in outlet. Velocity moment distribution in outlet was obtained during implementation of numerical research. Implemented bench tests of torque flow pump prototypes enabled to obtain real characteristics of pump and confirm effectiveness of spatial geometry of outlet application for such pump.

  7. Analytical calculation of the torque exerted between two perpendicularly magnetized magnets

    Science.gov (United States)

    Allag, H.; Yonnet, J.-P.; Latreche, M. E. H.

    2011-04-01

    Analytical expressions of the torque on cuboidal permanent magnets are given. The only hypothesis is that the magnetizations are rigid, uniform, and perpendicularly oriented. The analytical calculation is made by replacing magnetizations by distributions of magnetic charges on the magnet poles. The torque expressions are obtained using the Lorentz force method. The results are valid for any relative magnet position, and the torque can be obtained with respect to any reference point. Although these expressions seem rather complicated, they enable an extremely fast and accurate torque calculation on a permanent magnet in the presence of a magnetic field of another permanent magnet.

  8. Direct Torque Control System for Permanent Magnet Synchronous Machine with Fuzzy Speed Pi Regulator

    Science.gov (United States)

    Nabti, K.; Abed, K.; Benalla, H.

    2008-06-01

    The Permanent Magnet Synchronous Machine (PMSM) speed regulation with a conventional PI regulator reduces the speed control precision, increase the torque fluctuation, and consequentially low performances of the whole system. With utilisation of fuzzy logic method, this paper presents the self adaptation of conventional PI regulator parameters Kp and Ki (proportional and integral coefficients respectively), using to regulate the speed in Direct Torque Control strategy (DTC). The ripples of both torque and flux are reduced remarkable, small overshooting and good dynamic of the speed and torque. Simulation results verify the proposed method validity.

  9. A General and Intuitive Approach to Understand and Compare the Torque Production Capability of AC Machines

    DEFF Research Database (Denmark)

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand

    2014-01-01

    -frame, through complicated mathematical manipulations. This is a more mathematical approach rather than explaining the physics behind torque production, which even brings a lot of difficulties to specialist. This paper introduces a general and intuitive approach to obtain the dq-frame torque equation of various...... AC machines. In this method, torque equation can be obtained based on the intuitive physical understanding of the mechanism behind torque production. It is then approved to be applicable for general case, including rotor saliency and various types of magnetomotive force sources. As an application...

  10. SENSORLESS FLUX REGION MODIFICATION OF DTC CONTROLLED IM FOR TORQUE RIPPLE REDUCTION

    OpenAIRE

    USER, Yavuz; GULEZ, Kayhan; OZEN, Sukru

    2014-01-01

    A Direct Torque Control (DTC) drive allows direct and independent control of flux linkage and electromagnetic torque by the selection of optimum inverter switching tables. There is no need for any complex transformation of current or voltage. However, each vector selected from the switching table cannot produce the required accurate stator voltage vector to provide the desired torque and flux. This results in the production of ripples in the torque as well as flux waveforms. In this study, we...

  11. Loosening torque of Universal Abutment screws after cyclic loading: influence of tightening technique and screw coating.

    Science.gov (United States)

    Bacchi, Atais; Regalin, Alexandre; Bhering, Claudia Lopes Brilhante; Alessandretti, Rodrigo; Spazzin, Aloisio Oro

    2015-10-01

    The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading. Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at 10(6) cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%). The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000). The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws.

  12. Magnification of starting torques of dc motors by maximum power point trackers in photovoltaic systems

    Science.gov (United States)

    Appelbaum, J.; Singer, S.

    1989-01-01

    A calculation of the starting torque ratio of permanent magnet, series, and shunt-excited dc motors powered by solar cell arrays is presented for two cases, i.e., with and without a maximum-power-point tracker (MPPT). Defining motor torque magnification by the ratio of the motor torque with an MPPT to the motor torque without an MPPT, a magnification of 3 for the permanent magnet motor and a magnification of 7 for both the series and shunt motors are obtained. The study also shows that all motor types are less sensitive to solar insolation variation in systems including MPPTs as compared to systems without MPPTs.

  13. Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry.

    Science.gov (United States)

    Guilhem, Gaël; Giroux, Caroline; Couturier, Antoine; Maffiuletti, Nicola A

    2014-12-01

    This study aimed to evaluate the validity and test-retest reliability of trunk muscle strength testing performed with a latest-generation isokinetic dynamometer. Eccentric, isometric, and concentric peak torque of the trunk flexor and extensor muscles was measured in 15 healthy subjects. Muscle cross sectional area (CSA) and surface electromyographic (EMG) activity were respectively correlated to peak torque and submaximal isometric torque for erector spinae and rectus abdominis muscles. Reliability of peak torque measurements was determined during test and retest sessions. Significant correlations were consistently observed between muscle CSA and peak torque for all contraction types (r=0.74-0.85; P<0.001) and between EMG activity and submaximal isometric torque (r ⩾ 0.99; P<0.05), for both extensor and flexor muscles. Intraclass correlation coefficients were comprised between 0.87 and 0.95, and standard errors of measurement were lower than 9% for all contraction modes. The mean difference in peak torque between test and retest ranged from -3.7% to 3.7% with no significant mean directional bias. Overall, our findings establish the validity of torque measurements using the tested trunk module. Also considering the excellent test-retest reliability of peak torque measurements, we conclude that this latest-generation isokinetic dynamometer could be used with confidence to evaluate trunk muscle function for clinical or athletic purposes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. The Accuracy of New and Aged Mechanical Torque Devices Employed in Five Dental Implant Systems

    Directory of Open Access Journals (Sweden)

    Mehmet Ali Erdem

    2017-01-01

    Full Text Available Purpose. Friction-style and spring-style torque wrenches are used to tighten implant abutments and prosthetic screws. The mechanical stability of these torque wrenches is crucial for the implant–abutment connection. The purposes of this study were to assess the performance of five brands (Straumann, Zimmer, Implant KA, Bredent, and Biohorizons of wrench and to evaluate possible changes in applied torque values of aged wrenches. Materials and Methods. Five new and aged wrenches that had been used approximately 250 times in a 1-year period were tested. The torque applied by friction- and spring-style wrenches was measured with a specially designed strain gauge indicator. Descriptive statistics, the one-sample t-test, and the independent-samples t-test were used to analyze values obtained from all torque wrenches. Results. The accuracy of new and aged torque devices of all brands except Bredent differed significantly from the target values, but the mean values for aged and new wrenches did not differ significantly from each other (p>0.05. Values for the spring- and friction-type torque wrenches deviated from the target values by 11.6% and 10.2%, respectively. Conclusion. The accuracy of aged torque wrenches is adequate for prosthetic screw tightening, but that of new torque wrenches is unsatisfactory and must be examined carefully before delivery.

  15. Universal adaptive torque control for PM motors for field-weakening region operation

    Science.gov (United States)

    Royak, Semyon [Beachwood, OH; Harbaugh, Mark M [Richfield, OH; Breitzmann, Robert J [South Russel, OH; Nondahl, Thomas A [Wauwatosa, WI; Schmidt, Peter B [Franklin, WI; Liu, Jingbo [Milwaukee, WI

    2011-03-29

    The invention includes a motor controller and method for controlling a permanent magnet motor. In accordance with one aspect of the present technique, a permanent magnet motor is controlled by, among other things, receiving a torque command, determining a normalized torque command by normalizing the torque command to a characteristic current of the motor, determining a normalized maximum available voltage, determining an inductance ratio of the motor, and determining a direct-axis current based upon the normalized torque command, the normalized maximum available voltage, and the inductance ratio of the motor.

  16. A Practical Torque Estimation Method for Interior Permanent Magnet Synchronous Machine in Electric Vehicles.

    Science.gov (United States)

    Wu, Zhihong; Lu, Ke; Zhu, Yuan

    2015-01-01

    The torque output accuracy of the IPMSM in electric vehicles using a state of the art MTPA strategy highly depends on the accuracy of machine parameters, thus, a torque estimation method is necessary for the safety of the vehicle. In this paper, a torque estimation method based on flux estimator with a modified low pass filter is presented. Moreover, by taking into account the non-ideal characteristic of the inverter, the torque estimation accuracy is improved significantly. The effectiveness of the proposed method is demonstrated through MATLAB/Simulink simulation and experiment.

  17. A Practical Torque Estimation Method for Interior Permanent Magnet Synchronous Machine in Electric Vehicles.

    Directory of Open Access Journals (Sweden)

    Zhihong Wu

    Full Text Available The torque output accuracy of the IPMSM in electric vehicles using a state of the art MTPA strategy highly depends on the accuracy of machine parameters, thus, a torque estimation method is necessary for the safety of the vehicle. In this paper, a torque estimation method based on flux estimator with a modified low pass filter is presented. Moreover, by taking into account the non-ideal characteristic of the inverter, the torque estimation accuracy is improved significantly. The effectiveness of the proposed method is demonstrated through MATLAB/Simulink simulation and experiment.

  18. Averaging in cosmological models using scalars

    International Nuclear Information System (INIS)

    Coley, A A

    2010-01-01

    The averaging problem in cosmology is of considerable importance for the correct interpretation of cosmological data. A rigorous mathematical definition of averaging in a cosmological model is necessary. In general, a spacetime is completely characterized by its scalar curvature invariants, and this suggests a particular spacetime averaging scheme based entirely on scalars. We clearly identify the problems of averaging in a cosmological model. We then present a precise definition of a cosmological model, and based upon this definition, we propose an averaging scheme in terms of scalar curvature invariants. This scheme is illustrated in a simple static spherically symmetric perfect fluid cosmological spacetime, where the averaging scales are clearly identified.

  19. A family of nonlinear PID-like regulators for a class of torque-driven robot manipulators equipped with torque-constrained actuators

    Directory of Open Access Journals (Sweden)

    Adriana Salinas

    2016-02-01

    Full Text Available This article addresses the joint position control of torque-driven robot manipulators under actuators subject to torque saturation. Robots having viscous friction, but without gravity vector, are considered. By assuming a static model for the torque actuator (specifically, a model of nonlinear and non-differentiable hard saturation function, a family of nonlinear proportional–integral–derivative-like controllers is proposed. Lyapunov stability theory is used to establish conditions for local asymptotic stability of the closed-loop system. A notable feature of the proposed controller is that stability conditions do not depend on the saturation levels of the actuators. In addition, an experimental study complements the proposed theory.

  20. Coordinating bracket torque and incisor inclination : Part 3: Validity of bracket torque values in achieving norm inclinations.

    Science.gov (United States)

    Zimmer, Bernd; Sino, Hiba

    2018-03-19

    To analyze common values of bracket torque (Andrews, Roth, MBT, Ricketts) for their validity in achieving incisor inclinations that are considered normal by different cephalometric standards. Using the equations developed in part 1 (eU1 (BOP) = 90° - BT (U1) - TCA (U1) + α 1 - α 2 and eL1 (BOP) = 90° - BT (L1) - TCA (L1) + β 1 - β 2 ) (abbreviations see part 1) and the mean values (± SD) obtained as statistical measures in parts 1 and 2 of the study (α 1 and β 1 [1.7° ± 0.7°], α 2 [3.6° ± 0.3°], β 2 [3.2° ± 0.4°], TCA (U1) [24.6° ± 3.6°] and TCA (L1) [22.9° ± 4.3°]) expected (= theoretically anticipated) values were calculated for upper and lower incisors (U1 and L1) and compared to targeted (= cephalometric norm) values. For U1, there was no overlapping between the ranges of expected and targeted values, as the lowest targeted value of (58.3°; Ricketts) was higher than the highest expected value (56.5°; Andrews) relative to the bisected occlusal plane (BOP). Thus all of these torque systems will aim for flatter inclinations than prescribed by any of the norm values. Depending on target values, the various bracket systems fell short by 1.8-5.5° (Andrews), 6.8-10.5° (Roth), 11.8-15.5° (MBT), or 16.8-20.5° (Ricketts). For L1, there was good agreement of the MBT system with the Ricketts and Björk target values (Δ0.1° and Δ-0.8°, respectively), and both the Roth and Ricketts systems came close to the Bergen target value (both Δ2.3°). Depending on target values, the ranges of deviation for L1 were 6.3-13.2° for Andrews (Class II prescription), 2.3°-9.2° for Roth, -3.7 to -3.2° for MBT, and 2.3-9.2° for Ricketts. Common values of upper incisor bracket torque do not have acceptable validity in achieving normal incisor inclinations. A careful selection of lower bracket torque may provide satisfactory matching with some of the targeted norm values.

  1. Spin-orbit torques and charge pumping in crystalline magnets

    Science.gov (United States)

    Ciccarelli, Chiara

    In magnetic crystals with an inversion asymmetric unit cell a non-zero global spin-polarization is generated by an electrical current, which acts with a torque on the magnetisation exciting magnetic dynamics. This relativistic non-equilibrium spin phenomenon also has a reciprocal effect in which the excitation of magnons results in the pumping of a charge current. The possibility to manipulate/read magnetism with electrical currents is highly relevant for magnetic memories and other spintronic devices. I will start by reviewing our recent research on spin-orbit torques (SOTs) in crystalline magnets, in particular our very recent measurements of the crystalline SOT at room temperature in half-Heusler NiMnSb thin films. With this experiment we are able to fully characterise magnitude and symmetry of the SOTs. I will then talk about the first demonstration of magnonic charge pumping in crystal magnet GaMnAs. In this effect, which is the reciprocal effect of SOTs, the precessing ferromagnet pumps a charge current. Differently from spin pumping, which is commonly used to electrically detect magnetization dynamics, in charge pumping magnons are converted within the ferromagnet into high-frequency currents via the relativistic spin-orbit interaction, without the need of a secondary spin-charge conversion element, such as heavy metals with large spin Hall angle.

  2. Design and Modeling of a Novel Torque Vectoring Differential System

    Directory of Open Access Journals (Sweden)

    Chen Yu-Fan

    2017-01-01

    Full Text Available In this paper, a new concept torque vectoring differential (TVD system is presented. It is shown that the structure and the mechanism of the system, the operating methods, and the parameters design by a simulation program, i.e. SimulationX. First of all, the structure of the new TVD system is introduced, as well as the relevant mechanic equations. Second, we attempt to verify the feasibility and accuracy of SimulationX through establishing a simple mechanical model by MATLAB, so that the further modeling and simulation results of the new TVD system will be credible. Then, the simulation results at the setting conditions are presented. Finally, the sensitivity of the design parameters is analyzed, including adjusting the braking torque and the dimensions of the gear sets in the differential. According to these results, the characteristics of the new TVD system can be derived in order to develop the whole system with vehicle dynamic model in the next stage.

  3. A variable torque motor compatible with magnetic resonance imaging.

    Science.gov (United States)

    Roeck, W W; Ha, S-H; Farmaka, S; Nalcioglu, O

    2009-04-01

    High magnetic fields used in magnetic resonance imaging (MRI) do not allow the employment of conventional motors due to various incompatibility issues. This paper reports on a new motor that can operate in or near high field magnets used for MRI. The motor was designed to be operational with the MRI equipment and could be used in a rotating imaging gantry inside the magnet designed for dual modality imaging. Furthermore, it could also be used for image guided robotic interventional procedures inside a MRI system if so desired. The prototype motor was developed using magnetic resonance (MR) compatible materials, and its functionality with MR imaging was evaluated experimentally by measuring the performance of the motor and its effect on the MR image quality. Since in our application, namely, single photon emission tomography, the motor has to perform precise stepping of the gantry in small angular steps the most important parameter is the start-up torque. The experimental results showed that the motor has a start-up torque up to 1.37 Nm and rotates at 196 rpm when a constant voltage difference of 12 V is applied at a magnetic field strength of 1 T. The MR image quality was quantified by measuring the signal-to-noise of images acquired under different conditions. The results presented here indicate that the motor is MR compatible and could be used for rotating an imaging gantry or a surgical device inside the magnet.

  4. Spin transfer torque generated magnetic droplet solitons (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Chung, S. [Materials Physics, School of ICT, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Mohseni, S. M. [Materials Physics, School of ICT, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); NanOsc AB, Electrum 205, 164 40 Kista (Sweden); Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Sani, S. R. [Materials Physics, School of ICT, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); NanOsc AB, Electrum 205, 164 40 Kista (Sweden); Iacocca, E.; Dumas, R. K.; Pogoryelov, Ye. [Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Anh Nguyen, T. N. [Materials Physics, School of ICT, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Laboratory for Nanotechnology (LNT), Vietnam National University - Ho Chi Minh City (VNU-HCM), Ho Chi Minh City (Viet Nam); Muduli, P. K. [Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Eklund, A. [Devices and Circuits, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Hoefer, M. [Department of Mathematics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Åkerman, J., E-mail: johan.akerman@physics.gu.se [Materials Physics, School of ICT, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); NanOsc AB, Electrum 205, 164 40 Kista (Sweden)

    2014-05-07

    We present recent experimental and numerical advancements in the understanding of spin transfer torque generated magnetic droplet solitons. The experimental work focuses on nano-contact spin torque oscillators (NC-STOs) based on orthogonal (pseudo) spin valves where the Co fixed layer has an easy-plane anisotropy, and the [Co/Ni] free layer has a strong perpendicular magnetic anisotropy. The NC-STO resistance and microwave signal generation are measured simultaneously as a function of drive current and applied perpendicular magnetic field. Both exhibit dramatic transitions at a certain current dependent critical field value, where the microwave frequency drops 10 GHz, modulation sidebands appear, and the resistance exhibits a jump, while the magnetoresistance changes sign. We interpret these observations as the nucleation of a magnetic droplet soliton with a large fraction of its magnetization processing with an angle greater than 90°, i.e., around a direction opposite that of the applied field. This interpretation is corroborated by numerical simulations. When the field is further increased, we find that the droplet eventually collapses under the pressure from the Zeeman energy.

  5. Rotation and Negative Torque in Electrodynamically Bound Nanoparticle Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Sule, Nishant [James; Yifat, Yuval [James; Gray, Stephen K. [Center; Scherer, Norbert F. [James; Department

    2017-10-16

    We examine the formation and concomitant rotation of electrodynamically bound dimers (EBD) of 150nm diameter Ag nanoparticles trapped in circularly polarized focused Gaussian beams. The rotation frequency of an EBD increases linearly with the incident beam power, reaching high mean values of ~ 4kHz for a relatively low incident power of 14mW. Using a coupled-dipole/effective polarizability model, we reveal that retardation of the scattered fields and electrodynamic interactions can lead to a “negative torque” causing rotation of the EBD in the direction opposite to that of the circular polarization. This intriguing opposite-handed rotation due to negative torque is clearly demonstrated using electrodynamics-Langevin dynamics simulations by changing particle separations and thus varying the retardation effects. Finally, negative torque is also demonstrated in experiments from statistical analysis of the EBD trajectories. These results demonstrate novel rotational dynamics of nanoparticles in optical matter using circular polarization and open a new avenue to control orientational dynamics through coupling to interparticle separation.

  6. Free (Reactionless) Torque Generation - Or Free Propulsion Concept

    International Nuclear Information System (INIS)

    Djordjev, Bojidar

    2010-01-01

    The basic principle in Newtonian Mechanics is based upon equal and opposite forces. Placing the vectors of velocity, acceleration, force and momentum of interacting objects along a single line satisfies the claim it is a linear or a 1-D concept. Classical Mechanics states that there are two main kinds of motion, linear and angular motion. Similarly placing the vectors of angular velocity, angular acceleration, torque and angular momentum along a line in the case of rotation in fact brings a plane 2-D interaction to the well known 1-D Newtonian concept. This adaptation transforms Classical Mechanics into a 1-D concept as well and presents a conformation that the linear concept is the only possible one. The Laws of Conservation of Momentum and Angular Momentum are results of the 1-D concept. But the world contains 3 geometrical spatial dimensions. Within the 3-D world there can exist 1-D, 2-D and 3-D kinds of interaction. The question is how to believe that the 3-D world can really be composed of a 1-D interaction or interactions made equal to the 1-D concept only? Examine a gyroscope - the only one mechanical device that is capable of performing 3-D behavior. The problem is that a gyroscope cannot perform three permanent and unidirectional torques that are fixed in space acting about perpendicular axes. This impossibility conforms to a 1-D concept. The idea is to find a solution that can be achieved for the 3-D concept.

  7. Models and control for force/torque sensors in robotics

    International Nuclear Information System (INIS)

    Johansson, Gert.

    1992-01-01

    One of the important problems in automatic assembly is the relative positioning accuracy between the parts in the assembly process. Inaccurate positions cause large insertion forces, wear and might damage the parts. They can also completely disable the assembly process. A solution to this problem is to detect the positioning error and to make a relevant adjustment of the position or path. This thesis presents a solution based on active feedback of force/torque data from a wrist mounted sensor. A task independent control algorithm has been realized through a sensor model concept. The sensor model includes an algorithm that transforms force/torque input to relevant motion of the end effector. The transformation is specified by a set of parameters e.g. desired forces, compliance and stopping criteria. The problem with gravity forces for varying end effector orientation is compensated by an algorithm, divided into three complexity levels. The compensation method includes a calibration sequence to ensure valid end effector properties to be used in the algorithm. A problem with available robot technology is bad integration possibilities for external sensors. To allow necessary modifications and expansions, an open and general control system architecture is proposed. The architecture is based in a computer workstation and transputers in pipeline for the robot specific operations. (au)

  8. The average size of ordered binary subgraphs

    NARCIS (Netherlands)

    van Leeuwen, J.; Hartel, Pieter H.

    To analyse the demands made on the garbage collector in a graph reduction system, the change in size of an average graph is studied when an arbitrary edge is removed. In ordered binary trees the average number of deleted nodes as a result of cutting a single edge is equal to the average size of a

  9. Adaptive control of grip force to compensate for static and dynamic torques during object manipulation.

    Science.gov (United States)

    Crevecoeur, F; Giard, T; Thonnard, J-L; Lefèvre, P

    2011-12-01

    Manipulating a cup by the handle requires compensating for the torque induced by the moment of the mass of the cup relative to the location of the handle. In the present study, we investigated the control strategy of subjects asked to perform grip-lift movements with an object with center of mass located away from the grip axis. Participants were asked to lift the manipulandum with a two-fingers precision grip and stabilize it in front of a visual target. Subjects showed a gradual and slow adaptation of the grip-force scaling across trials: the grip force tended to decrease slowly, and the temporal coordination between grip-force and load-torque rates displayed gradually, better-coordinated patterns. Importantly, this adaptation was much slower than the stabilization of the same parameters measured either when no torque came into play or after previous adaptation to the presence of a torque. In contrast, the maximum rotation induced by the torque was controlled efficiently after only few trials, and an unexpected decrease in the tangential torque produced significant overcompensation. An unexpected increase in torque produced a consistent opposite effect. This shows that the compensation for the dynamic torque was based on an anticipatory, dynamic counter-torque produced by the arm and wrist motor commands. The comparatively slow stabilization of grip-force control suggests a specific adaptation process engaged by the presence of the torque. This paradigm, including tangential torques, clearly constitutes a powerful tool to extract the adaptive component of grip control during object manipulation.

  10. Optical torque on a magneto-dielectric Rayleigh absorptive sphere by a vector Bessel (vortex) beam

    Science.gov (United States)

    Li, Renxian; Yang, Ruiping; Ding, Chunying; Mitri, F. G.

    2017-04-01

    The optical torque exerted on an absorptive megneto-dielectric sphere by an axicon-generated vector Bessel (vortex) beam with selected polarizations is investigated in the framework of the dipole approximation. The total optical torque is expressed as the sum of orbital and spin torques. The axial orbital torque component is calculated from the z-component of the cross-product of the vector position r and the optical force exerted on the sphere F. Depending on the beam characteristics (such as the half-cone angle and polarization type) and the physical properties of the sphere, it is shown here that the axial orbital torque vanishes before reversing sign, indicating a counter-intuitive orbital motion in opposite handedness of the angular momentum carried by the incident waves. Moreover, analytical formulas for the spin torque, which is divided into spin torques induced by electric and magnetic dipoles, are derived. The corresponding components of both the optical spin and orbital torques are numerically calculated, and the effects of polarization, the order of the beam, and half-cone angle are discussed in detail. The left-handed (i.e., negative) optical torque is discussed, and the conditions for generating optical spin and orbital torque sign reversal are numerically investigated. The transverse optical spin torque has a vortex-like character, whose direction depends on the polarization, the half-cone angle, and the order of the beam. Numerical results also show that the vortex direction depends on the radial position of the particle in the transverse plane. This means that a sphere may rotate with different directions when it moves radially. Potential applications are in particle manipulation and rotation, single beam optical tweezers, and other emergent technologies using vector Bessel beams on a small magneto-dielectric (nano) particle.

  11. The acute effects of local muscle vibration frequency on peak torque, rate of torque development, and EMG activity.

    Science.gov (United States)

    Pamukoff, Derek N; Ryan, Eric D; Blackburn, J Troy

    2014-12-01

    Vibratory stimuli enhance muscle activity and may be used for rehabilitation and performance enhancement. Efficacy of vibration varies with the frequency of stimulation, but the optimal frequency is unclear. The purpose of this study was to examine the effects of 30 Hz and 60 Hz local muscle vibration (LMV) on quadriceps function. Twenty healthy volunteers (age = 20.4 ± 1.4 years, mass = 68.1 ± 11.0 kg, height = 170.1 ± 8.8 cm, males = 9) participated. Isometric knee extensor peak torque (PT), rate of torque development (RTD), and electromyography (EMG) of the quadriceps were assessed followed by one of the three LMV treatments (30 Hz, 60 Hz, control) applied under voluntary contraction, and again immediately, 5, 15, and 30 min post-treatment in three counterbalanced sessions. Dependent variables were analyzed using condition by time repeated-measures ANOVA. The condition × time interaction was significant for EMG amplitude (p = 0.001), but not for PT (p=0.324) or RTD (p = 0.425). The increase in EMG amplitude following 30 Hz LMV was significantly greater than 60 Hz LMV and control. These findings suggest that 30 Hz LMV may elicit an improvement in quadriceps activation and could be used to treat quadriceps dysfunction resulting from knee pathologies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Bayesian Model Averaging for Propensity Score Analysis.

    Science.gov (United States)

    Kaplan, David; Chen, Jianshen

    2014-01-01

    This article considers Bayesian model averaging as a means of addressing uncertainty in the selection of variables in the propensity score equation. We investigate an approximate Bayesian model averaging approach based on the model-averaged propensity score estimates produced by the R package BMA but that ignores uncertainty in the propensity score. We also provide a fully Bayesian model averaging approach via Markov chain Monte Carlo sampling (MCMC) to account for uncertainty in both parameters and models. A detailed study of our approach examines the differences in the causal estimate when incorporating noninformative versus informative priors in the model averaging stage. We examine these approaches under common methods of propensity score implementation. In addition, we evaluate the impact of changing the size of Occam's window used to narrow down the range of possible models. We also assess the predictive performance of both Bayesian model averaging propensity score approaches and compare it with the case without Bayesian model averaging. Overall, results show that both Bayesian model averaging propensity score approaches recover the treatment effect estimates well and generally provide larger uncertainty estimates, as expected. Both Bayesian model averaging approaches offer slightly better prediction of the propensity score compared with the Bayesian approach with a single propensity score equation. Covariate balance checks for the case study show that both Bayesian model averaging approaches offer good balance. The fully Bayesian model averaging approach also provides posterior probability intervals of the balance indices.

  13. Cosmological ensemble and directional averages of observables

    CERN Document Server

    Bonvin, Camille; Durrer, Ruth; Maartens, Roy; Umeh, Obinna

    2015-01-01

    We show that at second order ensemble averages of observables and directional averages do not commute due to gravitational lensing. In principle this non-commutativity is significant for a variety of quantities we often use as observables. We derive the relation between the ensemble average and the directional average of an observable, at second-order in perturbation theory. We discuss the relevance of these two types of averages for making predictions of cosmological observables, focussing on observables related to distances and magnitudes. In particular, we show that the ensemble average of the distance is increased by gravitational lensing, whereas the directional average of the distance is decreased. We show that for a generic observable, there exists a particular function of the observable that is invariant under second-order lensing perturbations.

  14. Spin-torque ferromagnetic resonance in arbitrarily magnetized thin films

    Science.gov (United States)

    Sklenar, Joseph

    The spin Hall effect (SHE) in non-magnetic metals can be used to generate spin-transfer-torque (STT), subsequently inducing ferromagnetic resonance (FMR) in magnetic thin films; this experimental method is termed spin-torque ferromagnetic resonance (ST-FMR). Most ST-FMR experiments that are reported have an applied magnetic field in the plane of the sample and the research focuses on material combinations that have large and efficient STT. The most common way ST-FMR signals are detected is through an anisotropic magnetoresistance (AMR) rectification process. In this work we will present ST-FMR results in thin films where the magnetization has both an in-plane and out-of-plane component. The arbitrary magnetization direction is achieved by tipping the applied magnetic field out of the sample plane. We find that when the material system is a permalloy/Pt bilayer, ST-FMR signals are not mirror-symmetric upon magnetic field reversal . This is because the combination of both a STT from the bulk SHE and the Oersted field-like torque from the device do not drive the dynamics in the same manner when the field is reversed. We interpret our results in the Py/Pt experiment by extending an already established ST-FMR lineshape model to describe the general case of arbitrarily magnetized films. We compare and contrast our Py/Pt experiment with another system we measured, a Py/MoS2 bilayer. For the Py/MoS2 system, in-plane experiments suggest that a large STT is present and are comparable to what is observed for the more traditional Py/Pt system . On the other hand, the out-of-plane experiment for the Py/MoS2 system is qualitatively very different from Py/Pt. Our results suggest that ST-FMR experiments for arbitrarily magnetized magnetic films are useful in characterizing STT generated from interface rather than bulk effects. Work at Northwestern was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science and Engineering Division under grant

  15. Quantitative analysis of peak torque and power-velocity characteristics of shoulder rotator muscles after arthroscopic labral repair.

    Science.gov (United States)

    Szuba, Łukasz; Markowska, Iga; Czamara, Andrzej; Noga, Henryk

    2016-10-01

    We aimed to use biomechanical testing to assess differences in the power and strength of patients who participated in a short-term, home-based rehabilitation program following arthroscopic labral repair compared with a healthy control group. The functional outcomes of patients who underwent arthroscopic labral repair followed by self-directed short-term rehabilitation at home were compared with age- and body mass index (BMI)-matched healthy controls. Group I included 20 male patients who had undergone arthroscopic labral repair after being diagnosed with recurrent anterior glenohumeral joint instability without bony lesions of the humeral head or glenoid. Postoperatively, they participated in physical therapy for 17±4 appointments, followed by self-guided home-based exercises. Group II included 25 males without injuries. The two groups were matched for age and BMI. The orthopaedic examination, functional tests, and biomechanical measurements were performed under isokinetic conditions at an average of 16±3 months postoperatively. Significant differences were observed in range of shoulder rotation on the operative shoulder compared with the unaffected side and in the dominant arms of the control group. The patients were also found to have significant deficits in biomechanical parameters such as power and peak torque angle. Significant deficits in peak torque, power, and peak torque angle during external and internal shoulder rotation remained up to 16 months after arthroscopic labral repair. Further research is needed to understand the changes in shoulder power assessment after labral repair. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  16. Spin-Orbit Torques and Anisotropic Magnetization Damping in Skyrmion Crystals

    Science.gov (United States)

    Hals, Kjetil; Brataas, Arne

    2014-03-01

    We theoretically study the effects of reactive and dissipative homogeneous spin-orbit torques and anisotropic damping on the current-driven skyrmion dynamics in cubic chiral magnets. Our results demonstrate that spin-orbit torques play a significant role in the current-induced skyrmion velocity. The dissipative spin-orbit torque generates a relativistic Magnus force on the skyrmions, whereas the reactive spin-orbit torque yields a correction to both the drift velocity along the current direction and the transverse velocity associated with the Magnus force. The spin-orbit torque corrections to the velocity scale linearly with the skyrmion size, which is inversely proportional to the spin-orbit coupling. Consequently, the reactive spin-orbit torque correction can be the same order of magnitude as the non-relativistic contribution. More importantly, the dissipative spin-orbit torque can be the dominant force that causes a deflected motion of the skyrmions if the torque exhibits a linear or quadratic relationship with the spin-orbit coupling. In addition, we demonstrate that the skyrmion velocity is determined by anisotropic magnetization damping parameters governed by the skyrmion size.

  17. The instantaneous torque-angular velocity relation in plantar flexion during jumping

    NARCIS (Netherlands)

    van Ingen Schenau, G J; Bobbert, M F; Huijing, P A; Woittiez, R D

    Torques, angular velocities, and power of the ankle joint during plantar flexion were measured in jumping experiments in order to achieve insight into shape and magnitude of the instantaneous torque-angular velocity relation in a complex movement. Twelve trained subjects performed maximal vertical

  18. A comparison of maximal torque levels of the different planes of ...

    African Journals Online (AJOL)

    It is often assumed that because different sports require specific skills, the torque levels differ from sport to sport. The purpose of this study was to establish whether there were significant differences in the maximal torque levels of the different planes of movement of the shoulder-girdle complex for different types of sport.

  19. Nonlinear Decoupling of Torque and Field Amplitude in an Induction Motor

    DEFF Research Database (Denmark)

    Rasmussen, Henrik; Vadstrup, P.; Børsting, H.

    1997-01-01

    A novel approach to control of induction motors, based on nonlinear state feedback, is presented. The resulting scheme gives a linearized input-output decoupling of the torque and the amplitude of the field. The proposed approach is used to design controllers for the field amplitude and the motor...... torque. The method is tested both by simulation and by experiments on a motor drive....

  20. Torque Optimization Algorithm for SRM Drives Using a Robust Predictive Strategy

    DEFF Research Database (Denmark)

    Argeseanu, Alin; Ritchie, Ewen; Leban, Krisztina Monika

    2010-01-01

    This paper presents a new torque optimization algorithm to maximize the torque generated by an SRM drive. The new algorithm uses a predictive strategy. The behaviour of the SRM demands a sequential algorithm. To preserve the advantages of SRM drives (simple and rugged topology) the new algorithm...

  1. Induction machine Direct Torque Control system based on fuzzy adaptive control

    Science.gov (United States)

    Li, Shi-ping; Yu, Yan; Jiao, Zhen-gang; Gu, Shu-sheng

    2009-07-01

    Direct Torque Control technology is a high-performance communication control method, it uses the space voltage vector method, and then to the inverter switch state control, to obtain high torque dynamic performance. But none of the switching states is able to generate the exact voltage vector to produce the desired changes in torque and flux in most of the switching instances. This causes a high ripple in torque. To solve this problem, a fuzzy implementation of Direct Torque Control of Induction machine is presented here. Error of stator flux, error of motor electromagnetic torque and position of angle of flux are taken as fuzzy variables. In order to further solve nonlinear problem of variation parameters in direct torque control system, the paper proposes a fuzzy parameter PID adaptive control method which is suitable for the direct torque control of an asynchronous motor. The generation of its fuzzy control is obtained by analyzing and optimizing PID control step response and combining expert's experience. For this reason, it carries out fuzzy work to PID regulator of motor speed to achieve to regulate PID parameters. Therefore the control system gets swifter response velocity, stronger robustness and higher precision of velocity control. The computer simulated results verify the validity of this novel method.

  2. Torque resistance of different stainless steel wires commonly used for fixed retainers in orthodontics

    DEFF Research Database (Denmark)

    Arnold, Dario; Dalstra, Michel; Verna, Carlalberta

    2016-01-01

    retainers in orthodontics. Materials and Methods: Torquing moments acting on a retainer wire were measured in a mechanical force testing system by applying buccal crown torque to an upper lateral incisor in both a 3-teeth and in a 2-teeth setup. Seven stainless steel wires with different shape, type (plain...

  3. Multi-digit maximum voluntary torque production on a circular object

    Science.gov (United States)

    SHIM, JAE KUN; HUANG, JUNFENG; HOOKE, ALEXANDER W.; LATSH, MARK L.; ZATSIORSKY, VLADIMIR M.

    2010-01-01

    Individual digit-tip forces and moments during torque production on a mechanically fixed circular object were studied. During the experiments, subjects positioned each digit on a 6-dimensional force/moment sensor attached to a circular handle and produced a maximum voluntary torque on the handle. The torque direction and the orientation of the torque axis were varied. From this study, it is concluded that: (1) the maximum torque in the closing (clockwise) direction was larger than in the opening (counter clockwise) direction; (2) the thumb and little finger had the largest and the smallest share of both total normal force and total moment, respectively; (3) the sharing of total moment between individual digits was not affected by the orientation of the torque axis or by the torque direction, while the sharing of total normal force between the individual digit varied with torque direction; (4) the normal force safety margins were largest and smallest in the thumb and little finger, respectively. PMID:17454086

  4. Estimation of torque transmitted by clutch during shifting process for dry dual clutch transmission

    Science.gov (United States)

    Zhao, Zhiguo; He, Lu; Yang, Yunyun; Wu, Chaochun; Li, Xueyan; Karl Hedrick, J.

    2016-06-01

    The key toward realizing no-impact gear shifting for dual clutch transmission (DCT) lies in the coordination control between the engine and dual clutches, as well as the accurate closed-loop control of torque transmitted by each clutch and the output torque of the engine. However, the implementation and control precision of closed-loop control are completely dependent on the effective measurement or estimation of the instant transmission torque of the clutch. This study analyzes the DCT shifting process, and builds a three-dimensional (3D) clutch model and mathematical model of a DCT vehicle powertrain system. The torque transmitted by a twin clutch during the upshifting process is estimated by applying the unscented Kalman filter (UKF) algorithm. Then, the torque estimation algorithm is verified using a DCT prototype vehicle installed with a torque sensor on the drive half-shaft. The experimental results show that the designed UKF torque estimation algorithm can estimate the transmission torques of two clutches in real time; further, it can be directly used for DCT shift control and improving the shifting quality.

  5. Optimal Design of Stator Interior Permanent Magnet Machine with Minimized Cogging Torque for Wind Power Application

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, Ming

    2008-01-01

    This paper proposes a new approach to minimize the cogging torque of a stator interior permanent magnet (SIPM) machine. The optimization of stator slot gap and permanent magnet is carried out and the cogging torque ripple is analyzed by using finite element analysis. Experiments on a prototype...

  6. A Method for Solving the Voltage and Torque Equations of the Split ...

    African Journals Online (AJOL)

    Akorede

    acceleration characteristics of the motor voltages, currents and electromagnetic torque have been plotted and discussed. The simulation results presented include the instantaneous torque-speed characteristics of the Split phase Induction machine. A block diagram of the method for the solution of the machine equations ...

  7. Barbell deadlift training increases the rate of torque development and vertical jump performance in novices.

    Science.gov (United States)

    Thompson, Brennan J; Stock, Matt S; Shields, JoCarol E; Luera, Micheal J; Munayer, Ibrahim K; Mota, Jacob A; Carrillo, Elias C; Olinghouse, Kendra D

    2015-01-01

    The primary purpose of this study was to examine the effects of 10 weeks of barbell deadlift training on rapid torque characteristics of the knee extensors and flexors. A secondary aim was to analyze the relationships between training-induced changes in rapid torque and vertical jump performance. Fifty-four subjects (age, mean ± SD = 23 ± 3 years) were randomly assigned to a control (n = 20) or training group (n = 34). Subjects in the training group performed supervised deadlift training twice per week for 10 weeks. All subjects performed isometric strength testing of the knee extensors and flexors and vertical jumps before and after the intervention. Torque-time curves were used to calculate rate of torque development (RTD) values at peak and at 50 and 200 milliseconds from torque onset. Barbell deadlift training induced significant pre- to post-increases of 18.8-49.0% for all rapid torque variables (p barbell deadlift training program was effective at enhancing rapid torque capacities in both the knee extensors and flexors. Changes in rapid torque were associated with improvements in vertical jump height, suggesting a transfer of adaptations from deadlift training to an explosive, performance-based task. Professionals may use these findings when attempting to design effective, time-efficient resistance training programs to improve explosive strength capacities in novices.

  8. Muscle Torque and its Relation to Technique, Tactics, Sports Level and Age Group in Judo Contestants

    Science.gov (United States)

    Lech, Grzegorz; Chwała, Wiesław; Ambroży, Tadeusz; Sterkowicz, Stanisław

    2015-01-01

    The aim of this study was to perform a comparative analysis of maximal muscle torques at individual stages of development of athletes and to determine the relationship between muscle torques, fighting methods and the level of sports performance. The activity of 25 judo contestants during judo combats and the effectiveness of actions were evaluated. Maximum muscle torques in flexors/extensors of the body trunk, shoulder, elbow, hip and knee joints were measured. The level of significance was set at p≤0.05; for multiple comparisons the Mann-Whitney U test, p≤0.016, was used. Intergroup differences in relative torques in five muscle groups studied (elbow extensors, shoulder flexors, knee flexors, knee extensors, hip flexors) were not significant. In cadets, relative maximum muscle torques in hip extensors correlated with the activity index (Spearman’s r=0.756). In juniors, maximum relative torques in elbow flexors and knee flexors correlated with the activity index (r=0.73 and r=0.76, respectively). The effectiveness of actions correlated with relative maximum torque in elbow extensors (r=0.67). In seniors, the relative maximum muscle torque in shoulder flexors correlated with the activity index during the second part of the combat (r=0.821). PMID:25964820

  9. Insertion torque and success of orthodontic mini-implants: A systematic review

    NARCIS (Netherlands)

    Meursinge Reynders, Reint A.; Ronchi, Laura; Ladu, Luisa; van Etten-Jamaludin, Faridi; Bipat, Shandra

    2012-01-01

    Introduction: In this systematic review, we analyzed whether recommended maximum insertion torque values of 5 to 10 Ncm were associated with higher success rates of orthodontic mini-implants compared with mini-implants inserted with maximum insertion torque values beyond this range. Objective

  10. Predicting the Onset of Cavitation in Automotive Torque Converters—Part I: Designs with Geometric Similitude

    Directory of Open Access Journals (Sweden)

    D. L. Robinette

    2008-01-01

    Full Text Available Dimensional analysis has been applied to automotive torque converters to understand the response of performance to changes in torque, size, working fluid, or operating temperature. The objective of this investigation was to develop a suitable dimensional analysis for estimating the effect of exact geometric scaling of a particular torque converter design on the onset of cavitation. Torque converter operating thresholds for cavitation were determined experimentally with a dynamometer test cell at the stall operating condition using nearfield acoustical measurements. Dimensionless quantities based upon either speed or torque at the onset of cavitation and flow properties (e.g., pressures and temperature dependent fluid properties were developed and compared. The proposed dimensionless stator torque quantity was found to be the most appropriate scaling law for extrapolating cavitation thresholds to multiple diameters. A power product model was fit on dimensionless stator torque data to create a model capable of predicting cavitation thresholds. Comparison of the model to test data taken over a range of operating points showed an error of 3.7%. This is the first paper of a two-part paper. In Part II, application of dimensional analysis will be expanded from torque converters with exact geometric similitude to those of more general design.

  11. Experimental and theoretical study of friction torque from radial ball bearings

    Science.gov (United States)

    Geonea, Ionut; Dumitru, Nicolae; Dumitru, Ilie

    2017-10-01

    In this paper it is presented a numerical simulation and an experimental study of total friction torque from radial ball bearings. For this purpose it is conceived a virtual CAD model of the experimental test bench for bearing friction torque measurement. The virtual model it is used for numerical simulation in Adams software, that allows dynamic study of multi-body systems and in particularly with facility Adams Machinery of dynamic behavior of machine parts. It is manufactured an experimental prototype of the test bench for radial ball bearings friction torque measurement. In order to measure the friction torque of the tested bearings it is used an equal resistance elastic beam element, with strain gauge transducer to measure bending deformations. The actuation electric motor of the bench has the shaft mounted on two bearings and the motor housing is fixed to the free side of the elastic beam, which is bended by a force proportional with the total friction torque. The beam elastic element with strain gauge transducer is calibrated in order to measure the force occurred. Experimental determination of the friction torque is made for several progressive radial loads. It is established the correlation from the friction torque and bearing radial load. The bench allows testing of several types and dimensions of radial bearings, in order to establish the bearing durability and of total friction torque.

  12. Quantifying anti-gravity torques for the design of a powered exoskeleton.

    Science.gov (United States)

    Ragonesi, Daniel; Agrawal, Sunil K; Sample, Whitney; Rahman, Tariq

    2013-03-01

    Designing an upper extremity exoskeleton for people with arm weakness requires knowledge of the joint torques due to gravity and joint stiffness, as well as, active residual force capabilities of users. The objective of this research paper is to describe the characteristics of the upper limb of children with upper limb impairment. This paper describes the experimental measurements of the torque on the upper limb due to gravity and joint stiffness of three groups of subjects: able-bodied adults, able-bodied children, and children with neuromuscular disabilities. The experiment involves moving the arm to various positions in the sagittal plane and measuring the resultant force at the forearm. This force is then converted to torques at the elbow and shoulder. These data are compared to a two-link lumped mass model based on anthropomorphic data. Results show that the torques based on anthropometry deviate from experimentally measured torques as the arm goes through the range. Subjects with disabilities also maximally pushed and pulled against the force sensor to measure maximum strength as a function of arm orientation. For all subjects, the maximum voluntary applied torque at the shoulder and elbow in the sagittal plane was found to be lower than gravity torques throughout the disabled subjects' range of motion. This experiment informs designers of upper limb orthoses on the contribution of passive human joint torques due to gravity and joint stiffness and the strength capability of targeted users.

  13. Leg dominancy in relation to fast isometric torque production and squat jump height

    NARCIS (Netherlands)

    de Ruiter, C.J.; de Korte, A.; Schreven, S.; de Haan, A.

    2010-01-01

    We hypothesized that maximal unilateral isometric knee extensor torque, the rate of torque development during maximally fast isometric contractions and unilateral squat jump performance would be better with the dominant than non-dominant leg. Limb dominancy was established using the step up, balance

  14. Muscle Torque and its Relation to Technique, Tactics, Sports Level and Age Group in Judo Contestants

    Directory of Open Access Journals (Sweden)

    Lech Grzegorz

    2015-03-01

    Full Text Available The aim of this study was to perform a comparative analysis of maximal muscle torques at individual stages of development of athletes and to determine the relationship between muscle torques, fighting methods and the level of sports performance.

  15. Torque And Speed in the Actuating of Mechatronic Systems, a Case Study

    Directory of Open Access Journals (Sweden)

    Constantin Paul Roman

    2015-12-01

    Full Text Available The paper presents a mechatronic system programmed and controlled by a PLC and inverter for driving an AC motor. Torque and speed for part of mechatronic systems depends of actuating source for cinematic structure. In our research, mechanical structure consists of an AC motor. A technique for setting and control of speed and torque is presented.

  16. Plantar flexor moment arm and muscle volume predict torque-generating capacity in young men.

    Science.gov (United States)

    Baxter, Josh R; Piazza, Stephen J

    2014-03-01

    Muscle volume is known to correlate with maximal joint torque in humans, but the role of muscle moment arm in determining maximal torque is less clear. Moderate correlations have been reported between maximal isometric knee extensor torque and knee extensor moment arm, but no such observations have been made for the ankle joint. It has been suggested that smaller muscle moment arms may enhance force generation at high rates of joint rotation, but this has not yet been observed for ankle muscles in vivo. The purpose of the present study was to correlate plantar flexor moment arm and plantar flexor muscle volume with maximal plantar flexor torque measured at different rates of plantar flexion. Magnetic resonance imaging was used to quantify the plantar flexor moment arm and muscle volume of the posterior compartment in 20 healthy young men. Maximal plantar flexor torque was measured isometrically and at three plantar flexion speeds using an isokinetic dynamometer. Plantar flexor torque was significantly correlated with muscle volume (0.222 muscle moment arm at each speed (0.323 muscle volume was strongly correlated with body mass and stature, moment arm was not. The slope of the torque-moment arm regression line decreased as the rate of joint rotation increased, indicating that subjects with small moment arms experienced smaller reductions in torque at high speeds. The findings of this study suggest that plantar flexor moment arm is a determinant of joint strength that is at least as important as muscle size.

  17. The accuracy of various torque wrenches used in dental implant systems

    Directory of Open Access Journals (Sweden)

    Mohammadreza Nakhaee

    2013-02-01

    Full Text Available Introduction: The purpose of this study was to compare the accuracy of the torque wrenches used in different dental implant systems. Methods: We evaluated 42 torque wrenches used in different dental clinics in Mashhad, Iran, using a digital torque meter (Mark 10. High (25, 30 and 35 N•cm and low (15 N•cm levels of torque were examined. Ten tests were performed on each wrench, and the mean value was considered as the real torque of the instrument. Different characteristics (Model (spring or friction, System, Duration of use, Sterilization, Calibration of each wrench were also recorded. The difference between the torque applied by the instrument and the target torque required was calculated numerically and as a percentage. A one-way ANOVA and Student’s t-test were used for statistical analysis. Results: There was a significant difference between the error at higher torques in the spring wrenches compared with the friction wrenches (P<0.05. At higher torques, an error greater than 10% was more common in the friction wrenches (29.4% than in the spring wrenches (4.3%. No significant differences were observed regarding the duration instruments usage and the mean numerical error at high and low torque. In the wrenches that had been used for more than three years, 21.1% of samples showed an error of more than 10%, compared with 9.5% in wrenches that had been used for less than three years (P=0.39. At higher torques the Straumann system produced the least error and the Biohorizon system produced the greatest error which was significantly greater than the other systems (P<0.05. Conclusion: Our results indicate that spring wrenches produce more accurate results than friction wrenches; however, friction wrenches are more reliable at lower torques than higher torques. The length of time in use and sterilization of torque wrenches does not affect the function of the instruments significantly. The precision of the instrument system used is also important.

  18. Parameter dependence of resonant spin torque magnetization reversal

    International Nuclear Information System (INIS)

    Fricke, L.; Serrano-Guisan, S.; Schumacher, H.W.

    2012-01-01

    We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

  19. Parameter dependence of resonant spin torque magnetization reversal

    Science.gov (United States)

    Fricke, L.; Serrano-Guisan, S.; Schumacher, H. W.

    2012-04-01

    We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

  20. Flux-Based Deadbeat Control of Induction-Motor Torque

    Science.gov (United States)

    Kenny, Barbara H.; Lorenz, Robert D.

    2003-01-01

    An improved method and prior methods of deadbeat direct torque control involve the use of pulse-width modulation (PWM) of applied voltages. The prior methods are based on the use of stator flux and stator current as state variables, leading to mathematical solutions of control equations in forms that do not lend themselves to clear visualization of solution spaces. In contrast, the use of rotor and stator fluxes as the state variables in the present improved method lends itself to graphical representations that aid in understanding possible solutions under various operating conditions. In addition, the present improved method incorporates the superposition of high-frequency carrier signals for use in a motor-self-sensing technique for estimating the rotor shaft angle at any speed (including low or even zero speed) without need for additional shaft-angle-measuring sensors.

  1. Low torque hydrodynamic lip geometry for rotary seals

    Science.gov (United States)

    Dietle, Lannie L.; Schroeder, John E.

    2015-07-21

    A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.

  2. IPMSM Motion-Sensorless Direct Torque and Flux Control

    DEFF Research Database (Denmark)

    Pitict, Christian Ilie; Andreescu, Gheorghe-Daniel; Blaabjerg, Frede

    2005-01-01

    The paper presents a rather comprehensive implementation of a wide speed motion-sensorless control of IPMSM drives via direct torque and flux control (DTFC) with space vector modulation (SVM). Signal injection with only one D-module vector filter and phase-locked loop (PLL) observer is used at low...... speeds to estimate the rotor position and speed, to be used in the stator flux observer and, respectively, as speed feedback. A combined voltage-current model flux observer suits the whole speed range, while the current model fades away as speed increases. PWM and inverter nonlinearities compensation...... provides for a smooth current waveform even at 1 rpm. The paper demonstrates through ample experiments a 1750 rpm 1 1 rpm speed range full-loaded with sensorless DTFC-SVM....

  3. Modelling the Load Torques of Electric Drive for Polymerization Process

    Directory of Open Access Journals (Sweden)

    Andrzej Popenda

    2007-01-01

    Full Text Available The problems of mathematical modelling the load torques on shaft of driving motor designed for applications in polymerization reactors are presented in the paper. The real load of polymerization drive is determined as a function of angular velocity. Mentioned function results from friction in roll-formed slide bearing as well as from friction of ethylene molecules with mixer arms in polymerization reactor chamber. Application of mathematical formulas concerning the centrifugal ventilator is proposed to describe the mixer in reactor chamber. The analytical formulas describing the real loads of polymerization drive are applied in mathematical modelling the power unit of polymerization reactor with specially designed induction motor. The numerical analysis of transient states was made on the basis of formulated mathematical model. Examples of transient responses and trajectories resulting from analysis are presented in the paper.

  4. Lane Departure Avoidance Control for Electric Vehicle Using Torque Allocation

    Directory of Open Access Journals (Sweden)

    Yiwan Wu

    2018-01-01

    Full Text Available This paper focuses on the lane departure avoidance system for a four in-wheel motors’ drive electric vehicle, aiming at preventing lane departure under dangerous driving conditions. The control architecture for the lane departure avoidance system is hierarchical. In the upper controller, the desired yaw rate was calculated with the consideration of vehicle-lane deviation, vehicle dynamic, and the limitation of road adhesion. In the middle controller, a sliding mode controller (SMC was designed to control the additional yaw moment. In the lower layer, the yaw moment was produced by the optimal distribution of driving/braking torque between four wheels. Lane departure avoidance was carried out by tracking desired yaw response. Simulations were performed to study the effectiveness of the control algorithm in Carsim®/Simulink® cosimulation. Simulation results show that the proposed methods can effectively confine the vehicle in lane and prevent lane departure accidents.

  5. Spin-orbit torque induced spike-timing dependent plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Abhronil, E-mail: asengup@purdue.edu; Al Azim, Zubair; Fong, Xuanyao; Roy, Kaushik [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2015-03-02

    Nanoelectronic devices that mimic the functionality of synapses are a crucial requirement for performing cortical simulations of the brain. In this work, we propose a ferromagnet-heavy metal heterostructure that employs spin-orbit torque to implement spike-timing dependent plasticity. The proposed device offers the advantage of decoupled spike transmission and programming current paths, thereby leading to reliable operation during online learning. Possible arrangement of such devices in a crosspoint architecture can pave the way for ultra-dense neural networks. Simulation studies indicate that the device has the potential of achieving pico-Joule level energy consumption (maximum 2 pJ per synaptic event) which is comparable to the energy consumption for synaptic events in biological synapses.

  6. Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals

    KAUST Repository

    Li, Hang

    2016-01-11

    We study spin-orbit torques in two-dimensional hexagonal crystals such as graphene, silicene, germanene, and stanene. The torque possesses two components, a fieldlike term due to inverse spin galvanic effect and an antidamping torque originating from Berry curvature in mixed spin-k space. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. The valley imbalance can be as high as 100% by tuning the bias voltage or magnetization angle. These findings open new venues for the development of current-driven spin-orbit torques by structural design.

  7. Comparison of torque measurements and near-infrared spectroscopy in characterization of a wet granulation process

    DEFF Research Database (Denmark)

    Jørgensen, Anna Cecilia; Luukkonen, Pirjo; Rantanen, Jukka

    2004-01-01

    The purpose of this study was to compare impeller torque measurements and near-infrared (NIR) spectroscopy in the characterization of the water addition phase of a wet granulation process. Additionally, the effect of hydrate formation during granulation on the impeller torque was investigated....... Anhydrous theophylline, alpha-lactose monohydrate, and microcrystalline cellulose (MCC) were used as materials for the study. The materials and mixtures of them were granulated using purified water in a small-scale high-shear mixer. The impeller torque was registered and NIR spectra of wet samples were...... recorded at-line. The torque and the NIR baseline-corrected water absorbances increased with increasing water content. A plateau in the NIR baseline-corrected water absorbances was observed for wet masses containing MCC. This was at the region of optimal water amount for granulation according to the torque...

  8. Supervisor control strategy of synchronizer for wet DCT based on online estimation of clutch drag torque

    Science.gov (United States)

    Lu, Tongli; Li, Hongkui; Zhang, Jianwu; Hao, Hongtao

    2016-01-01

    The objective of this paper is to improve the performance of the synchronizer control strategy by considering the effect of clutch drag torque. The research of synchronization process in wet dual clutch transmission is performed in this paper. The significant effect of clutch drag torque is analyzed by adding a complex clutch drag torque module to synchronizer model. This paper focuses on the development of original estimation method of clutch drag torque. The estimation method offers an effective way to obtain accurate clutch drag torque, and it is applied to develop a new supervisor control strategy. Results have demonstrated that the estimation method has satisfied efficiency and accuracy and the control strategy improves the performance of the synchronizer mechanism significantly.

  9. Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction

    KAUST Repository

    Ortiz Pauyac, Christian

    2016-06-19

    In the present thesis we introduce the reader to the field of spintronics and explore new phenomena, such as spin transfer torques, spin filtering, and three types of spin-orbit torques, Rashba, spin Hall, and spin swapping, which have emerged very recently and are promising candidates for a new generation of memory devices in computer technology. A general overview of these phenomena is presented in Chap. 1. In Chap. 2 we study spin transfer torques in tunnel junctions in the presence of spin filtering. In Chap. 3 we discuss the Rashba torque in ferromagnetic films, and in Chap. 4 we study spin Hall effect and spin swapping in ferromagnetic films, exploring the nature of spin-orbit torques based on these mechanisms. Conclusions and perspectives are summarized in Chap. 5.

  10. Quantifying anti-gravity torques in the design of a powered exoskeleton.

    Science.gov (United States)

    Ragonesi, Daniel; Agrawal, Sunil; Sample, Whitney; Rahman, Tariq

    2011-01-01

    Designing an upper extremity exoskeleton for people with arm weakness requires knowledge of the passive and active residual force capabilities of users. This paper experimentally measures the passive gravitational torques of 3 groups of subjects: able-bodied adults, able bodied children, and children with neurological disabilities. The experiment involves moving the arm to various positions in the sagittal plane and measuring the gravitational force at the wrist. This force is then converted to static gravitational torques at the elbow and shoulder. Data are compared between look-up table data based on anthropometry and empirical data. Results show that the look-up torques deviate from experimentally measured torques as the arm reaches up and down. This experiment informs designers of Upper Limb orthoses on the contribution of passive human joint torques.

  11. Coordinating bracket torque and incisor inclination : Part 2: Reproducibility and statistical measures of the torque coordination angle (TCA).

    Science.gov (United States)

    Sino, H; Zimmer, B; Schelper, I; Schenk-Kazan, S; Streibelt, F

    2018-03-09

    To determine the reproducibility and statistical measures of the torque coordination angle (TCA). A total of 107 final cephalograms and corresponding casts were included, all reflecting treatment outcomes that met high qualitative standards, one of them being a Peer Assessment Rating (PAR) score of ≤3. Based on these records, the TCA was measured as a parameter to identify differences related to tooth morphology and bracket position between the torque-relevant reference plane at the bracket base and the long axis of a tooth. All measurements were performed on upper and lower central incisors (U1 and L1). Several reproducibility assessments for the TCA measurements yielded good results, including objectivity at 1.26 ± 0.81° (U1) or 1.41 ± 1.18° (L1), examiner reliability at 1.30 ± 0.97° (U1) or 1.25 ± 0.82° (L1), and method reliability at 1.80 ± 1.13° (U1) or 1.53 ± 1.07° (L1). The statistical measures revealed a high degree of interindividual variability. With bracket placement 4.5 mm (U1) or 4.0 mm (L1) above the incisal edge, the differences between the maximum and minimum TCA values were similarly large in both jaws (21.0° for U1 or 20.0° for L1), given mean TCA values of 24.6 ± 3.6° (U1) or 22.9 ± 4.3° (L1). Moving the bracket placement from 3.5 to 5.5 mm (U1) or from 3.0 to 5.0 mm (L1) changed the mean TCA values by 4.5° (U1) or 3.2° (L1). The TCA is a suitable cephalometric parameter to identify differences related to tooth morphology and bracket placement. Given its high interindividual variability, the fixed torque value of a specific bracket system should not be expected to produce the same incisor inclinations across patients.

  12. Magnification of starting torques of dc motors by maximum power point trackers in photovoltaic systems

    Science.gov (United States)

    Appelbaum, Joseph; Singer, S.

    1989-01-01

    Direct current (dc) motors are used in terrestrial photovoltaic (PV) systems such as in water-pumping systems for irrigation and water supply. Direct current motors may also be used for space applications. Simple and low weight systems including dc motors may be of special interest in space where the motors are directly coupled to the solar cell array (with no storage). The system will operate only during times when sufficient insolation is available. An important performance characteristic of electric motors is the starting to rated torque ratio. Different types of dc motors have different starting torque ratios. These ratios are dictated by the size of solar cell array, and the developed motor torque may not be sufficient to overcome the load starting torque. By including a maximum power point tracker (MPPT) in the PV system, the starting to rated torque ratio will increase, the amount of which depends on the motor type. The starting torque ratio is calculated for the permanent magnet, series and shunt excited dc motors when powered by solar cell arrays for two cases: with and without MPPT's. Defining a motor torque magnification by the ratio of the motor torque with an MPPT to the motor torque without an MPPT, a magnification of 3 was obtained for the permanent magnet motor and a magnification of 7 for both the series and shunt motors. The effect of the variation of solar insolation on the motor starting torque was covered. All motor types are less sensitive to insolation variation in systems including MPPT's as compared to systems with MPPT's. The analysis of this paper will assist the PV system designed to determine whether or not to include an MPPT in the system for a specific motor type.

  13. Spacetime averaging of exotic singularity universes

    International Nuclear Information System (INIS)

    Dabrowski, Mariusz P.

    2011-01-01

    Taking a spacetime average as a measure of the strength of singularities we show that big-rips (type I) are stronger than big-bangs. The former have infinite spacetime averages while the latter have them equal to zero. The sudden future singularities (type II) and w-singularities (type V) have finite spacetime averages. The finite scale factor (type III) singularities for some values of the parameters may have an infinite average and in that sense they may be considered stronger than big-bangs.

  14. NOAA Average Annual Salinity (3-Zone)

    Data.gov (United States)

    California Department of Resources — The 3-Zone Average Annual Salinity Digital Geography is a digital spatial framework developed using geographic information system (GIS) technology. These salinity...

  15. NOAA Average Annual Salinity (3-Zone)

    Data.gov (United States)

    California Natural Resource Agency — The 3-Zone Average Annual Salinity Digital Geography is a digital spatial framework developed using geographic information system (GIS) technology. These salinity...

  16. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  17. Fixed Average Spectra of Orchestral Instrument Tones

    Directory of Open Access Journals (Sweden)

    Joseph Plazak

    2010-04-01

    Full Text Available The fixed spectrum for an average orchestral instrument tone is presented based on spectral data from the Sandell Harmonic Archive (SHARC. This database contains non-time-variant spectral analyses for 1,338 recorded instrument tones from 23 Western instruments ranging from contrabassoon to piccolo. From these spectral analyses, a grand average was calculated, providing what might be considered an average non-time-variant harmonic spectrum. Each of these tones represents the average of all instruments in the SHARC database capable of producing that pitch. These latter tones better represent common spectral changes with respect to pitch register, and might be regarded as an “average instrument.” Although several caveats apply, an average harmonic tone or instrument may prove useful in analytic and modeling studies. In addition, for perceptual experiments in which non-time-variant stimuli are needed, an average harmonic spectrum may prove to be more ecologically appropriate than common technical waveforms, such as sine tones or pulse trains. Synthesized average tones are available via the web.

  18. Grassmann Averages for Scalable Robust PCA

    DEFF Research Database (Denmark)

    Hauberg, Søren; Feragen, Aasa; Black, Michael J.

    2014-01-01

    to vectors (subspaces) or elements of vectors; we focus on the latter and use a trimmed average. The resulting Trimmed Grassmann Average (TGA) is particularly appropriate for computer vision because it is robust to pixel outliers. The algorithm has low computational complexity and minimal memory requirements...

  19. Bayesian Averaging is Well-Temperated

    DEFF Research Database (Denmark)

    Hansen, Lars Kai

    2000-01-01

    is less clear if the teacher distribution is unknown. I define a class of averaging procedures, the temperated likelihoods, including both Bayes averaging with a uniform prior and maximum likelihood estimation as special cases. I show that Bayes is generalization optimal in this family for any teacher...

  20. Averaging Einstein's equations : The linearized case

    NARCIS (Netherlands)

    Stoeger, William R.; Helmi, Amina; Torres, Diego F.

    We introduce a simple and straightforward averaging procedure, which is a generalization of one which is commonly used in electrodynamics, and show that it possesses all the characteristics we require for linearized averaging in general relativity and cosmology for weak-field and perturbed FLRW

  1. Determinants of College Grade Point Averages

    Science.gov (United States)

    Bailey, Paul Dean

    2012-01-01

    Chapter 2: The Role of Class Difficulty in College Grade Point Averages. Grade Point Averages (GPAs) are widely used as a measure of college students' ability. Low GPAs can remove a students from eligibility for scholarships, and even continued enrollment at a university. However, GPAs are determined not only by student ability but also by the…

  2. Analysis of the torque capacity of a completely customized lingual appliance of the next generation

    Science.gov (United States)

    2014-01-01

    Introduction In lingual orthodontic therapy, effective torque control of the incisors is crucial due to the biomechanical particularities associated with the point of force application and the tight link between third order deviations and vertical tooth position. Aim The aim of the present in vitro investigation was to analyze the torque capacity of a completely customized lingual appliance of the next generation (WIN) in combination with different finishing archwire dimensions. Methods Using a typodont of the upper arch carrying the WIN appliance, slot filling and undersized individualized β-titanium archwires were engaged. Horizontal forces ranging from 0 to 100 cN were applied at the central incisor by means of spring gauges. The resulting angular deviations were recorded and the corresponding torque moments were calculated. Results For fullsize archwires (0.018”×0.018” β-titanium and 0.018”×0.025” β-titanium), an initial torque play of 0-2° had to be overcome prior to the development of an effective torque moment. Thereafter, a linear correlation between torque angle and torque moment developed for both archwire dimensions with steeper slopes calculated for the specimens with the larger dimension. A torque moment of 2 Nmm required for effective torque correction was noted after a minimum of 2-3° of twist for the 0.018”×0.018” β-titanium wires as compared to 2-4° for the 0.018”×0.025” β-titanium study sample. When undersized archwires were analyzed (0.0175”×0.0175” β-titanium), the measured torque play ranged from 5-7°. After 8-12° of torque angle, the threshold of 2 Nmm was reached. A linear relationship between twist angle and torque moment in which the steepness of the slopes was generally flatter than the ones calculated for the slot filling archwires was noted. Conclusions Given the high precision of the bracket slot-archwire-combination provided with the WIN appliance, an effective torque control can be clinically

  3. Average action for models with fermions

    International Nuclear Information System (INIS)

    Bornholdt, S.; Wetterich, C.

    1993-01-01

    The average action is a new tool for investigating spontaneous symmetry breaking in elementary particle theory and statistical mechanics beyond the validity of standard perturbation theory. The aim of this work is to provide techniques for an investigation of models with fermions and scalars by means of the average potential. In the phase with spontaneous symmetry breaking, the inner region of the average potential becomes flat as the averaging extends over infinite volume and the average potential approaches the convex effective potential. Fermion fluctuations in this region necessitate a calculation of the fermion determinant in a spin wave background. We also compute the fermionic contribution to the wave function renormalization in the scalar kinetic term. (orig.)

  4. Peripheral arterial disease decreases muscle torque and functional walking capacity in elderly.

    Science.gov (United States)

    Dziubek, Wioletta; Bulińska, Katarzyna; Stefańska, Małgorzata; Woźniewski, Marek; Kropielnicka, Katarzyna; Jasiński, Tomasz; Jasiński, Ryszard; Pilch, Urszula; Dąbrowska, Grażyna; Skórkowska-Telichowska, Katarzyna; Wojcieszczyk-Latos, Joanna; Kałka, Dariusz; Janus, Agnieszka; Zywar, Katarzyna; Paszkowski, Rafał; Szuba, Andrzej

    2015-08-01

    The aim of this study is to compare values of force-velocity and functional walking capacity in elderly patients with intermittent claudication with respect to the control group. The study involved 135 individuals: 85-peripheral arterial disease (PAD) group diagnosed with stage II chronic lower limb ischemia, according to Fontaine's classification, and 50-control group. The studies included an assessment of walking capacity using a six-minute walk test (6MWT) and measurement of force-velocity parameters (peak torque-PTQ, total work-TW, average power-AVGP) of the lower limbs obtained by means of a functional dynamometry under isokinetic conditions. The peripheral arterial disease group is characterized by significantly lower values of force-velocity parameters compared to the control group (pmuscle strength in the isokinetic test. Mean values of all force-velocity parameters and walk distance were significantly higher in the control group than in the peripheral arterial disease group. In the PAD group, in both men and women, the value of the agonist/antagonist ratio of both lower limbs are lower in men and women comparing to the control group. A rehabilitation program for patients with intermittent claudication must consider exercises improving strength, exercise capacity, and endurance in patients with PAD. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  5. Small scale magnetic flux-averaged magnetohydrodynamics

    International Nuclear Information System (INIS)

    Pfirsch, D.; Sudan, R.N.

    1994-01-01

    By relaxing exact magnetic flux conservation below a scale λ a system of flux-averaged magnetohydrodynamic equations are derived from Hamilton's principle with modified constraints. An energy principle can be derived from the linearized averaged system because the total system energy is conserved. This energy principle is employed to treat the resistive tearing instability and the exact growth rate is recovered when λ is identified with the resistive skin depth. A necessary and sufficient stability criteria of the tearing instability with line tying at the ends for solar coronal loops is also obtained. The method is extended to both spatial and temporal averaging in Hamilton's principle. The resulting system of equations not only allows flux reconnection but introduces irreversibility for appropriate choice of the averaging function. Except for boundary contributions which are modified by the time averaging process total energy and momentum are conserved over times much longer than the averaging time τ but not for less than τ. These modified boundary contributions correspond to the existence, also, of damped waves and shock waves in this theory. Time and space averaging is applied to electron magnetohydrodynamics and in one-dimensional geometry predicts solitons and shocks in different limits

  6. Reduction of Cogging Torque in Dual Rotor Permanent Magnet Generator for Direct Coupled Wind Energy Systems

    Directory of Open Access Journals (Sweden)

    Sivachandran Paulsamy

    2014-01-01

    Full Text Available In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG for direct coupled stand alone wind energy systems (SAWES. Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  7. Torque Characteristic Analysis of a Transverse Flux Motor Using a Combined-Type Stator Core

    Directory of Open Access Journals (Sweden)

    Xiaobao Yang

    2016-11-01

    Full Text Available An external rotor transverse flux motor using a combined-type stator core is proposed for a direct drive application in this paper. The stator core is combined by two kinds of components that can both be manufactured conveniently by generic laminated silicon steel used in traditional motors. The motor benefits from the predominance of low manufacturing cost and low iron loss by using a silicon-steel sheet. Firstly, the basic structure and operation principles of the proposed motor are introduced. Secondly, the expressions of the electromagnetic torque and the cogging torque are deduced by theoretical analysis. Thirdly, the basic characteristics such as permanent magnet flux linkage, no-load back electromotive force, cogging torque and electromagnetic torque are analyzed by a three-dimensional finite element method (3D FEM. Then, the influence of structure parameters on the torque density is investigated, which provides a useful foundation for optimum design of the novel motor. Finally, the torque density of the proposed motor is calculated and discussed, and the result shows that the proposed motor in this paper can provide considerable torque density by using few permanent magnets.

  8. Optimal design and selection of magneto-rheological brake types based on braking torque and mass

    International Nuclear Information System (INIS)

    Nguyen, Q H; Lang, V T; Choi, S B

    2015-01-01

    In developing magnetorheological brakes (MRBs), it is well known that the braking torque and the mass of the MRBs are important factors that should be considered in the product’s design. This research focuses on the optimal design of different types of MRBs, from which we identify an optimal selection of MRB types, considering braking torque and mass. In the optimization, common types of MRBs such as disc-type, drum-type, hybrid-type, and T-shape types are considered. The optimization problem is to find an optimal MRB structure that can produce the required braking torque while minimizing its mass. After a brief description of the configuration of the MRBs, the MRBs’ braking torque is derived based on the Herschel-Bulkley rheological model of the magnetorheological fluid. Then, the optimal designs of the MRBs are analyzed. The optimization objective is to minimize the mass of the brake while the braking torque is constrained to be greater than a required value. In addition, the power consumption of the MRBs is also considered as a reference parameter in the optimization. A finite element analysis integrated with an optimization tool is used to obtain optimal solutions for the MRBs. Optimal solutions of MRBs with different required braking torque values are obtained based on the proposed optimization procedure. From the results, we discuss the optimal selection of MRB types, considering braking torque and mass. (technical note)

  9. A theoretical model of speed-dependent steering torque for rolling tyres

    Science.gov (United States)

    Wei, Yintao; Oertel, Christian; Liu, Yahui; Li, Xuebing

    2016-04-01

    It is well known that the tyre steering torque is highly dependent on the tyre rolling speed. In limited cases, i.e. parking manoeuvre, the steering torque approaches the maximum. With the increasing tyre speed, the steering torque decreased rapidly. Accurate modelling of the speed-dependent behaviour for the tyre steering torque is a key factor to calibrate the electric power steering (EPS) system and tune the handling performance of vehicles. However, no satisfactory theoretical model can be found in the existing literature to explain this phenomenon. This paper proposes a new theoretical framework to model this important tyre behaviour, which includes three key factors: (1) tyre three-dimensional transient rolling kinematics with turn-slip; (2) dynamical force and moment generation; and (3) the mixed Lagrange-Euler method for contact deformation solving. A nonlinear finite-element code has been developed to implement the proposed approach. It can be found that the main mechanism for the speed-dependent steering torque is due to turn-slip-related kinematics. This paper provides a theory to explain the complex mechanism of the tyre steering torque generation, which helps to understand the speed-dependent tyre steering torque, tyre road feeling and EPS calibration.

  10. A rationale method for evaluating unscrewing torque values of prosthetic screws in dental implants

    Directory of Open Access Journals (Sweden)

    Felipe Miguel Saliba

    2011-02-01

    Full Text Available OBJECTIVES: Previous studies that evaluated the torque needed for removing dental implant screws have not considered the manner of transfer of the occlusal loads in clinical settings. Instead, the torque used for removal was applied directly to the screw, and most of them omitted the possibility that the hexagon could limit the action of the occlusal load in the loosening of the screws. The present study proposes a method for evaluating the screw removal torque in an anti-rotational device independent way, creating an unscrewing load transfer to the entire assembly, not only to the screw. MATERIAL AND METHODS: Twenty hexagonal abutments without the hexagon in their bases were fixed with a screw to 20 dental implants. They were divided into two groups: Group 1 used titanium screws and Group 2 used titanium screws covered with a solid lubricant. A torque of 32 Ncm was applied to the screw and then a custom-made wrench was used for rotating the abutment counterclockwise, to loosen the screw. A digital torque meter recorded the torque required to loosen the abutment. RESULTS: There was a significant difference between the means of Group 1 (38.62±6.43 Ncm and Group 2 (48.47±5.04 Ncm, with p=0.001. CONCLUSION: This methodology was effective in comparing unscrewing torque values of the implant-abutment junction even with a limited sample size. It confirmed a previously shown significant difference between two types of screws.

  11. Strength and endurance training reduces the loss of eccentric hamstring torque observed after soccer specific fatigue.

    Science.gov (United States)

    Matthews, Martyn J; Heron, Kate; Todd, Stefanie; Tomlinson, Andrew; Jones, Paul; Delextrat, Anne; Cohen, Daniel D

    2017-05-01

    To investigate the effect of two hamstring training protocols on eccentric peak torque before and after soccer specific fatigue. Twenty-two university male soccer players. Isokinetic strength tests were performed at 60°/s pre and post fatigue, before and after 2 different training interventions. A 45-min soccer specific fatigue modified BEAST protocol (M-BEAST) was used to induce fatigue. Players were randomly assigned to a 4 week hamstrings conditioning intervention with either a maximum strength (STR) or a muscle endurance (END) emphasis. The following parameters were evaluated: Eccentric peak torque (EccPT), angle of peak torque (APT), and angle specific torques at knee joint angles of 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° and 90°. There was a significant effect of the M-BEAST on the Eccentric torque angle profile before training as well as significant improvements in post-fatigue torque angle profile following the effects of both strength and muscle endurance interventions. Forty-five minutes of simulated soccer activity leads to reduced eccentric hamstring torque at longer muscle lengths. Short-term conditioning programs (4-weeks) with either a maximum strength or a muscular endurance emphasis can equally reduce fatigue induced loss of strength over this time period. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Torque Split Strategy for Parallel Hybrid Electric Vehicles with an Integrated Starter Generator

    Directory of Open Access Journals (Sweden)

    Zhumu Fu

    2014-01-01

    Full Text Available This paper presents a torque split strategy for parallel hybrid electric vehicles with an integrated starter generator (ISG-PHEV by using fuzzy logic control. By combining the efficiency map and the optimum torque curve of the internal combustion engine (ICE with the state of charge (SOC of the batteries, the torque split strategy is designed, which manages the ICE within its peak efficiency region. Taking the quantified ICE torque, the quantified SOC of the batteries, and the quantified ICE speed as inputs, and regarding the output torque demanded on the ICE as an output, a fuzzy logic controller (FLC with relevant fuzzy rules has been developed to determine the optimal torque distribution among the ICE, the ISG, and the electric motor/generator (EMG effectively. The simulation results reveal that, compared with the conventional torque control strategy which uses rule-based controller (RBC in different driving cycles, the proposed FLC improves the fuel economy of the ISG-PHEV, increases the efficiency of the ICE, and maintains batteries SOC within its operation range more availably.

  13. Implant Insertion Torque: Its Role in Achieving Primary Stability of Restorable Dental Implants.

    Science.gov (United States)

    Greenstein, Gary; Cavallaro, John

    2017-02-01

    A literature review was conducted to determine the role of insertion torque in attaining primary stability of dental implants. The review is comprised of articles that discussed the amount of torque needed to achieve primary implant stability in healed ridges and fresh extraction sockets prior to immediate implant loading. Studies were appraised that addressed the effects of minimum and maximum forces that can be used to successfully place implants. The minimum torque that can be employed to attain primary stability is undefined. Forces ≥30 Ncm are routinely used to place implants into healed ridges and fresh extraction sockets prior to immediate loading of implants. Increased insertion torque (≥50 Ncm) reduces micromotion and does not appear to damage bone. In general, the healing process after implant insertion provides a degree of biologic stability that is similar whether implants are placed with high or low initial insertion torque. Primary stability is desirable when placing implants, but the absence of micromotion is what facilitates predictable implant osseointegration. Increased insertion torque helps achieve primary stability by reducing implant micromotion. Furthermore, tactile information provided by the first surgical twist drill can aid in selecting the initial insertion torque to achieve predictable stability of inserted dental implants.

  14. Torque Measurement of 3-DOF Haptic Master Operated by Controllable Electrorheological Fluid

    Directory of Open Access Journals (Sweden)

    Oh Jong-Seok

    2015-02-01

    Full Text Available This work presents a torque measurement method of 3-degree-of-freedom (3-DOF haptic master featuring controllable electrorheological (ER fluid. In order to reflect the sense of an organ for a surgeon, the ER haptic master which can generate the repulsive torque of an organ is utilized as a remote controller for a surgery robot. Since accurate representation of organ feeling is essential for the success of the robot-assisted surgery, it is indispensable to develop a proper torque measurement method of 3-DOF ER haptic master. After describing the structural configuration of the haptic master, the torque models of ER spherical joint are mathematically derived based on the Bingham model of ER fluid. A new type of haptic device which has pitching, rolling, and yawing motions is then designed and manufactured using a spherical joint mechanism. Subsequently, the field-dependent parameters of the Bingham model are identified and generating repulsive torque according to applied electric field is measured. In addition, in order to verify the effectiveness of the proposed torque model, a comparative work between simulated and measured torques is undertaken.

  15. Spin-orbit torques in locally and globally noncentrosymmetric crystals: Antiferromagnets and ferromagnets

    KAUST Repository

    Železný, J.

    2017-01-10

    One of the main obstacles that prevents practical applications of antiferromagnets is the difficulty of manipulating the magnetic order parameter. Recently, following the theoretical prediction [J. Železný, Phys. Rev. Lett. 113, 157201 (2014)]PRLTAO0031-900710.1103/PhysRevLett.113.157201, the electrical switching of magnetic moments in an antiferromagnet was demonstrated [P. Wadley, Science 351, 587 (2016)]SCIEAS0036-807510.1126/science.aab1031. The switching is due to the so-called spin-orbit torque, which has been extensively studied in ferromagnets. In this phenomena a nonequilibrium spin-polarization exchange coupled to the ordered local moments is induced by current, hence exerting a torque on the order parameter. Here we give a general systematic analysis of the symmetry of the spin-orbit torque in locally and globally noncentrosymmetric crystals. We study when the symmetry allows for a nonzero torque, when is the torque effective, and its dependence on the applied current direction and orientation of magnetic moments. For comparison, we consider both antiferromagnetic and ferromagnetic orders. In two representative model crystals we perform microscopic calculations of the spin-orbit torque to illustrate its symmetry properties and to highlight conditions under which the spin-orbit torque can be efficient for manipulating antiferromagnetic moments.

  16. Torque Measurement of 3-DOF Haptic Master Operated by Controllable Electrorheological Fluid

    Science.gov (United States)

    Oh, Jong-Seok; Choi, Seung-Bok; Lee, Yang-Sub

    2015-02-01

    This work presents a torque measurement method of 3-degree-of-freedom (3-DOF) haptic master featuring controllable electrorheological (ER) fluid. In order to reflect the sense of an organ for a surgeon, the ER haptic master which can generate the repulsive torque of an organ is utilized as a remote controller for a surgery robot. Since accurate representation of organ feeling is essential for the success of the robot-assisted surgery, it is indispensable to develop a proper torque measurement method of 3-DOF ER haptic master. After describing the structural configuration of the haptic master, the torque models of ER spherical joint are mathematically derived based on the Bingham model of ER fluid. A new type of haptic device which has pitching, rolling, and yawing motions is then designed and manufactured using a spherical joint mechanism. Subsequently, the field-dependent parameters of the Bingham model are identified and generating repulsive torque according to applied electric field is measured. In addition, in order to verify the effectiveness of the proposed torque model, a comparative work between simulated and measured torques is undertaken.

  17. Reduction of cogging torque in dual rotor permanent magnet generator for direct coupled wind energy systems.

    Science.gov (United States)

    Paulsamy, Sivachandran

    2014-01-01

    In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  18. The influence of aging on the isometric torque sharing patterns among the plantar flexor muscles.

    Science.gov (United States)

    Oliveira, Liliam F; Verneque, Debora; Menegaldo, Luciano L

    2017-01-01

    Physiological cross-sectional area (PCSA) reduction of the triceps surae (TS) muscles during aging suggests a proportional loss of torque among its components: soleus, medial and lateral gastrocnemii. However, direct measurements of muscle forces in vivo are not feasible. The purpose of this paper was to compare, between older and young women, isometric ankle joint torque sharing patterns among TS muscles and tibialis anterior (TA). An EMG-driven model was used for estimating individual muscle torque contributions to the total plantar flexor torque, during sustained contractions of 10% and 40% of maximum voluntary contraction (MVC). Relative individual muscle contributions to the total plantar flexion torque were similar between older and young women groups, for both intensities, increasing from LG, MG to SOL. Muscle strength (muscle torque/body mass) was significantly greater for all TS components in 40% MVC contractions. Increased TA activation was observed in 10% of MVC for older people. Despite the reduced maximum isometric torque and muscle strength, the results suggest small variations of ankle muscle synergies during the aging process.

  19. Correlation between architectural variables and torque in the erector spinae muscle during maximal isometric contraction.

    Science.gov (United States)

    Cuesta-Vargas, Antonio; González-Sánchez, Manuel

    2014-01-01

    This study analysed whether a significant relationship exists between the torque and muscle thickness and pennation angle of the erector spinae muscle during a maximal isometric lumbar extension with the lumbar spine in neutral position. This was a cross-sectional study in which 46 healthy adults performed three repetitions for 5 s of maximal isometric lumbar extension with rests of 90 s. During the lumbar extensions, bilateral ultrasound images of the erector spinae muscle (to measure pennation angle and muscle thickness) and torque were acquired. Reliability test analysis calculating the internal consistency (Cronbach's alpha) of the measure, correlation between pennation angle, muscle thickness and torque extensions were examined. Through a linear regression the contribution of each independent variable (muscle thickness and pennation angle) to the variation of the dependent variable (torque) was calculated. The results of the reliability test were: 0.976-0.979 (pennation angle), 0.980-0.980 (muscle thickness) and 0.994 (torque). The results show that pennation angle and muscle thickness were significantly related to each other with a range between 0.295 and 0.762. In addition, multiple regression analysis showed that the two variables considered in this study explained 68% of the variance in the torque. Pennation angle and muscle thickness have a moderate impact on the variance exerted on the torque during a maximal isometric lumbar extension with the lumbar spine in neutral position.

  20. Average-passage flow model development

    Science.gov (United States)

    Adamczyk, John J.; Celestina, Mark L.; Beach, Tim A.; Kirtley, Kevin; Barnett, Mark

    1989-01-01

    A 3-D model was developed for simulating multistage turbomachinery flows using supercomputers. This average passage flow model described the time averaged flow field within a typical passage of a bladed wheel within a multistage configuration. To date, a number of inviscid simulations were executed to assess the resolution capabilities of the model. Recently, the viscous terms associated with the average passage model were incorporated into the inviscid computer code along with an algebraic turbulence model. A simulation of a stage-and-one-half, low speed turbine was executed. The results of this simulation, including a comparison with experimental data, is discussed.

  1. Computation of the bounce-average code

    International Nuclear Information System (INIS)

    Cutler, T.A.; Pearlstein, L.D.; Rensink, M.E.

    1977-01-01

    The bounce-average computer code simulates the two-dimensional velocity transport of ions in a mirror machine. The code evaluates and bounce-averages the collision operator and sources along the field line. A self-consistent equilibrium magnetic field is also computed using the long-thin approximation. Optionally included are terms that maintain μ, J invariance as the magnetic field changes in time. The assumptions and analysis that form the foundation of the bounce-average code are described. When references can be cited, the required results are merely stated and explained briefly. A listing of the code is appended

  2. Cosmic inhomogeneities and averaged cosmological dynamics.

    Science.gov (United States)

    Paranjape, Aseem; Singh, T P

    2008-10-31

    If general relativity (GR) describes the expansion of the Universe, the observed cosmic acceleration implies the existence of a "dark energy." However, while the Universe is on average homogeneous on large scales, it is inhomogeneous on smaller scales. While GR governs the dynamics of the inhomogeneous Universe, the averaged homogeneous Universe obeys modified Einstein equations. Can such modifications alone explain the acceleration? For a simple generic model with realistic initial conditions, we show the answer to be "no." Averaging effects negligibly influence the cosmological dynamics.

  3. Peak torque of quadriceps and hamstring muscles in basketball and soccer players of different divisions.

    Science.gov (United States)

    Zakas, A; Mandroukas, K; Vamvakoudis, E; Christoulas, K; Aggelopoulou, N

    1995-09-01

    Basketball and soccer are two games with different training and playing procedures. The purpose of this study was to examine the maximal voluntary peak torques of the quadriceps and hamstring muscles, and the torque ratio between these muscle groups in basketball players (n = 61) and soccer players (n = 51) participating in teams of different divisions. Isokinetic peak torques were measured using the Cybex II isokinetic dynamometer at 60 and 180 degrees.s-1. Basketball players of the national team produced higher peak torque values of quadriceps muscles than the other basketball players of different divisions (p Hamstring peak torques of the national basketball team were significantly higher the only velocities measured compared with the players from division II and IV (p quadriceps muscles relative to body weight were significantly higher in the national basketball team compared with basketball players from division I. No significant differences were found in peak torque values of quadriceps and hamstring muscles within the different basketball and soccer divisions. Peak torque expressed in absolute terms was significantly higher in basketball players than in soccer players (p quadriceps and hamstring muscles was expressed relative to body weight. The H/Q ratio did not differ either ditto among the different divisions of basketball and soccer players. Based on the data obtained in this study, we concluded that the subjects' body weight have a decisive effect on the production of peak torque values of quadriceps and hamstring muscles in basketball and soccer players. Furthermore that the playing in different divisions, as well as participating in different sports, i.e. basketball or soccer, have surprisingly small effects on the peak isokinetic torque production of the quadriceps and hamstring muscles.

  4. Influence of magnetic reluctances of magnetic elements on servo valve torque motors

    Science.gov (United States)

    Liu, Changhai; Jiang, Hongzhou

    2016-01-01

    The current research of electro-hydraulic servo valves mainly focuses on the vibration, pressure oscillating and source of noise. Unfortunately, literatures relating to the study of the influence of the magnetic reluctances of the magnetic elements are rarely available. This paper aims to analyze the influence of the magnetic reluctances of the magnetic elements on torque motor. Considering these magnetic reluctances ignored in previous literatures, a new mathematical model of servo valve torque motor is developed and proposed based on the fundamental laws of electromagnetism. By using this new mathematical model and the previous models, electromagnetic torque constant and magnetic spring stiffness are evaluated for a given set of torque motor parameters. A computer simulation by using AMESim software is also performed for the same set of torque motor parameters to verify the proposed model. The theoretical results of electromagnetic torque constant and magnetic spring stiffness evaluated by the proposed model render closer agreement with the simulation results than those evaluated by the previous models. In addition, an experimental measurement of the magnetic flux densities in the air-gaps is carried out by using SFL218 servo valve torque motor. Compared with the theoretical results of the magnetic flux densities in the air-gaps evaluated by the previous models, the theoretical results evaluated by the proposed model also show better agreement with the experimental data. The proposed model shows the influence of the magnetic reluctances of the magnetic elements on the servo valve torque motor, and offers modified and analytical expressions to electromagnetic torque constant and magnetic spring stiffness. These modified and analytical expressions could provide guidance more accurately for a linear control design approach and sensitivity analysis on electro-hydraulic servo valves than the previous expressions.

  5. Change in knee flexor torque after fatiguing exercise identifies previous hamstring injury in football players.

    Science.gov (United States)

    Lord, C; Ma'ayah, F; Blazevich, A J

    2018-03-01

    Muscular fatigue and interlimb strength asymmetry are factors known to influence hamstring injury risk; however, limb-specific exacerbation of knee flexor (hamstrings) torque production after fatiguing exercise has previously been ignored. To investigate changes in muscular force production before and after sport-specific (repeated-sprint) and non-specific (knee extension-flexion) fatiguing exercise, and explore the sensitivity and specificity of isokinetic endurance (ie, muscle-specific) and single-leg vertical jump (ie, whole limb) tests to identify previous hamstring injury. Twenty Western Australia State League footballers with previous unilateral hamstring injury and 20 players without participated. Peak concentric knee extensor and flexor (180°∙s -1 ) torques were assessed throughout an isokinetic endurance test, which was then repeated alongside a single-leg vertical jump test before and after maximal repeated-sprint exercise. Greater reductions in isokinetic knee flexor torque (-16%) and the concentric hamstring:quadriceps peak torque ratio (-15%) were observed after repeated-sprint running only in the injured (kicking) leg and only in the previously injured subjects. Changes in (1) peak knee flexor torque after repeated-sprint exercise, and (2) the decline in knee flexor torque during the isokinetic endurance test measured after repeated-sprint exercise, correctly identified the injured legs (N = 20) within the cohort (N = 80) with 100% specificity and sensitivity. Decreases in peak knee flexor torque and the knee flexor torque during an isokinetic endurance test after repeated-sprint exercise identified previous hamstring injury with 100% accuracy. Changes in knee flexor torque, but not SLVJ, should be tested to determine its prospective ability to predict hamstring injury in competitive football players. © 2017 The Authors. Scandinavian Journal of Medicine & Science In Sports Published by John Wiley & Sons Ltd.

  6. Skinfold thickness affects the isometric knee extension torque evoked by Neuromuscular Electrical Stimulation

    Directory of Open Access Journals (Sweden)

    Flávia V. A. Medeiros

    2015-12-01

    Full Text Available BACKGROUND: Subcutaneous adipose tissue may influence the transmission of electrical stimuli through to the skin, thus affecting both evoked torque and comfort perception associated with neuromuscular electrical stimulation (NMES. This could seriously affect the effectiveness of NMES for either rehabilitation or sports purposes. OBJECTIVE: To investigate the effects of skinfold thickness (SFT on maximal NMES current intensity, NMES-evoked torque, and NMES-induced discomfort. METHOD: First, we compared NMES current intensity, NMES-induced discomfort, and NMES-evoked torque between two subgroups of subjects with thicker (n=10; 20.7 mm vs. thinner (n=10; 29.4 mm SFT. Second, we correlated SFT to NMES current intensity, NMES-induced discomfort, and NMES-evoked knee extension torque in 20 healthy women. The NMES-evoked torque was normalized to the maximal voluntary contraction (MVC torque. The discomfort induced by NMES was assessed with a visual analog scale (VAS. RESULTS: NMES-evoked torque was 27.5% lower in subjects with thicker SFT (p=0.01 while maximal current intensity was 24.2% lower in subjects with thinner SFT (p=0.01. A positive correlation was found between current intensity and SFT (r=0.540, p=0.017. A negative correlation was found between NMES-evoked torque and SFT (r=-0.563, p=0.012. No significant correlation was observed between discomfort scores and SFT (rs=0.15, p=0.53. CONCLUSION: These results suggest that the amount of subcutaneous adipose tissue (as reflected by skinfold thickness affected NMES current intensity and NMES-evoked torque, but had no effect on discomfort perception. Our findings may help physical therapists to better understand the impact of SFT on NMES and to design more rational stimulation strategies.

  7. Selective use of hand and forearm muscles during bone screw insertion: a natural torque meter.

    Science.gov (United States)

    Barros, Sérgio Estelita; Janson, Guilherme; Chiqueto, Kelly; Ferreira, Eduardo Silveira; Janson, Marcos

    2012-11-01

    To compare the maximum torque produced by different muscle groups and its influence on mini-implant insertion torque and fracture prevention. Eighty-seven professionals were evaluated for the maximum torque produced on a screwdriver by a combined action between the thumb and index finger (maximum digital torque [MDT]) and by the forearm supination movement (maximum brachial torque [MBT]). Ninety mini-implants distributed among 9 different diameters were fractured to determine the fracture torque (FT). The fracture resistance index (FRI) was obtained from: FRI_MDT = FT/MDT and FRI_MBT = FT/MBT. Analysis of variance and t tests were used to compare the groups. The MDT was smaller than the MBT, and the 2 measurements were smaller in female subjects. The FT increased for each 0.1-mm increment in diameter. The FRI_MDT was greater than FRI_MBT for all diameters. An FRI_MDT greater than 1 was found when the diameter was greater than or equal to 1.5 mm. An FRI_MBT greater than 1 occurred with diameters equal to or greater than 1.7 mm for female subjects and 1.8 mm for male subjects. The digital torque was 42% smaller than the brachial torque, and it was mechanically safer and biologically more compatible, allowing the prevention of the fracture of mini-implants with a diameter 1.5 mm or thicker owing to an insertion torque limitation at 15 N-cm. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  8. Spin Currents and Spin Orbit Torques in Ferromagnets and Antiferromagnets

    Science.gov (United States)

    Hung, Yu-Ming

    This thesis focuses on the interactions of spin currents and materials with magnetic order, e.g., ferromagnetic and antiferromagnetic thin films. The spin current is generated in two ways. First by spin-polarized conduction-electrons associated with the spin Hall effect in heavy metals (HMs) and, second, by exciting spin-waves in ferrimagnetic insulators using a microwave frequency magnetic field. A conduction-electron spin current can be generated by spin-orbit coupling in a heavy non-magnetic metal and transfer its spin angular momentum to a ferromagnet, providing a means of reversing the magnetization of perpendicularly magnetized ultrathin films with currents that flow in the plane of the layers. The torques on the magnetization are known as spin-orbit torques (SOT). In the first part of my thesis project I investigated and contrasted the quasistatic (slowly swept current) and pulsed current-induced switching characteristics of micrometer scale Hall crosses consisting of very thin (thesis project studies and considers applications of SOT-driven domain wall (DW) motion in a perpendicularly magnetized ultrathin ferromagnet sandwiched between a heavy metal and an oxide. My experiment results demonstrate that the DW motion can be explained by a combination of the spin Hall effect, which generates a SOT, and Dzyaloshinskii-Moriya interaction, which stabilizes chiral Neel-type DW. Based on SOT-driven DW motion and magnetic coupling between electrically isolated ferromagnetic elements, I proposed a new type of spin logic devices. I then demonstrate the device operation by using micromagnetic modeling which involves studying the magnetic coupling induced by fringe fields from chiral DWs in perpendicularly magnetized nanowires. The last part of my thesis project reports spin transport and spin-Hall magnetoresistance (SMR) in yttrium iron garnet Y3Fe5O 12 (YIG)/NiO/Pt trilayers with varied NiO thickness. To characterize the spin transport through NiO we excite

  9. Sensorless load torque estimation and passivity based control of buck converter fed DC motor.

    Science.gov (United States)

    Kumar, S Ganesh; Thilagar, S Hosimin

    2015-01-01

    Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper.

  10. Sensorless Load Torque Estimation and Passivity Based Control of Buck Converter Fed DC Motor

    Directory of Open Access Journals (Sweden)

    S. Ganesh Kumar

    2015-01-01

    Full Text Available Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper.

  11. Reduction of torque ripple in DTC induction motor drive with discrete voltage vectors

    Directory of Open Access Journals (Sweden)

    Rosić Marko

    2014-01-01

    Full Text Available This paper presents а practical implementation of direct torque control (DTC of an induction machine on MSK2812 DSP platform, and the analysis of possibilities for reduction of torque ripple. Basic theoretical background relating the DTC was primarily set and the obtained experimental results have been given. It is shown that the torque ripple can be reduced by adjusting the intensity of voltage vectors and by modification of hysteresis comparator, while the simplicity of the basic DTC algorithm has been maintained. [Projekat Ministarstva nauke Republike Srbije, br. TR33016

  12. Design of driving control strategy of torque distribution for two - wheel independent drive electric vehicle

    Science.gov (United States)

    Zhang, Chuanwei; Zhang, Dongsheng; Wen, Jianping

    2018-02-01

    In order to coordinately control the torque distribution of existing two-wheel independent drive electric vehicle, and improve the energy efficiency and control stability of the whole vehicle, the control strategies based on fuzzy control were designed which adopt the direct yaw moment control as the main line. For realizing the torque coordination simulation of the two-wheel independent drive vehicle, the vehicle model, motor model and tire model were built, including the vehicle 7 - DOF dynamics model, motion equation, torque equation. Finally, in the Carsim - Simulink joint simulation platform, the feasibility of the drive control strategy was verified.

  13. Aspects Concerning the Torque Ripple Control of the Brushless DC Motor

    Directory of Open Access Journals (Sweden)

    BALUTA, G.

    2013-05-01

    Full Text Available This paper deals with two advanced numerical structures to control the electromagnetic torque ripple of Brushless Direct Current Motors (BLDCM, indirectly achieved by phase currents control and directly by the Direct Torque Control (DTC technique. In DTC there was implemented an observer to increase the rudimentary transducer resolution, containing three Hall Effect sensors. The experimental results describe the evolution of torque in both situations of control and are obtained by applying a control strategy for an electric drive system with BLDCM with trapezoidal Back-EMF in Two-Phase Mode.

  14. Analytical torque calculation and experimental verification of synchronous permanent magnet couplings with Halbach arrays

    Science.gov (United States)

    Seo, Sung-Won; Kim, Young-Hyun; Lee, Jung-Ho; Choi, Jang-Young

    2018-05-01

    This paper presents analytical torque calculation and experimental verification of synchronous permanent magnet couplings (SPMCs) with Halbach arrays. A Halbach array is composed of various numbers of segments per pole; we calculate and compare the magnetic torques for 2, 3, and 4 segments. Firstly, based on the magnetic vector potential, and using a 2D polar coordinate system, we obtain analytical solutions for the magnetic field. Next, through a series of processes, we perform magnetic torque calculations using the derived solutions and a Maxwell stress tensor. Finally, the analytical results are verified by comparison with the results of 2D and 3D finite element analysis and the results of an experiment.

  15. Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

    KAUST Repository

    Ghosh, Sumit

    2017-01-24

    We investigate spin transport in two-dimensional ferromagnetic (FTI) and antiferromagnetic (AFTI) topological insulators. In the presence of an in-plane magnetization AFTI supports zero energy modes, which enables topologically protected edge conduction at low energy. We address the nature of current-driven spin torque in these structures and study the impact of spin-independent disorder. Interestingly, upon strong disorder the spin torque develops an antidamping component (i.e., even upon magnetization reversal) along the edges, which could enable current-driven manipulation of the antiferromagnetic order parameter. This antidamping torque decreases when increasing the system size and when the system enters the trivial insulator regime.

  16. Monthly snow/ice averages (ISCCP)

    Data.gov (United States)

    National Aeronautics and Space Administration — September Arctic sea ice is now declining at a rate of 11.5 percent per decade, relative to the 1979 to 2000 average. Data from NASA show that the land ice sheets in...

  17. Sea Surface Temperature Average_SST_Master

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea surface temperature collected via satellite imagery from http://www.esrl.noaa.gov/psd/data/gridded/data.noaa.ersst.html and averaged for each region using ArcGIS...

  18. MN Temperature Average (1961-1990) - Line

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data set depicts 30-year averages (1961-1990) of monthly and annual temperatures for Minnesota. Isolines and regions were created using kriging and...

  19. Schedule of average annual equipment ownership expense

    Science.gov (United States)

    2003-03-06

    The "Schedule of Average Annual Equipment Ownership Expense" is designed for use on Force Account bills of Contractors performing work for the Illinois Department of Transportation and local government agencies who choose to adopt these rates. This s...

  20. Should the average tax rate be marginalized?

    Czech Academy of Sciences Publication Activity Database

    Feldman, N. E.; Katuščák, Peter

    -, č. 304 (2006), s. 1-65 ISSN 1211-3298 Institutional research plan: CEZ:MSM0021620846 Keywords : tax * labor supply * average tax Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/wp/Wp304.pdf

  1. Static stretching vs. dynamic warm-ups: a comparison of their effects on torque and electromyography output of the quadriceps and hamstring muscles.

    Science.gov (United States)

    Williams, N; Coburn, J; Gillum, T

    2015-11-01

    The aim of this paper was to determine if two different warm-up protocols differently affect torque of the quadriceps and hamstrings, and electromyography (EMG) output of the rectus femoris (RF) and vastus lateralis (VL) when completing 30 maximal leg extensions and curls. Twenty-one healthy male (N.=8) and female (N.=13) subjects volunteered to participate in a familiarization session and three testing sessions. The three testing sessions control, dynamic, and static were completed in a counterbalanced order on non-consecutive days. First, subjects warmed-up on a treadmill for five minutes before completing six dynamic movements, six static-stretches, or no stretches. They then rested for five minutes before completing 30 maximal leg extensions and curls at a speed of 60 s-1. A significant decrease in quadriceps torque output over time was determined for the dynamic protocol when compared to the control (Pstatic (Pstatic, and a significant increase was found for the static protocol (Pstatic (Pstatic-stretching has the ability to increase peak and average torque of the leg extensors, while some types of anaerobic exercise involving maximal contractions to fatigue may be hindered by performing dynamic movements as part of the warm-up.

  2. Whole body oxygen uptake and evoked torque during subtetanic isometric electrical stimulation of the quadriceps muscles in a single 30-minute session.

    Science.gov (United States)

    Minogue, Conor M; Caulfield, Brian M; Lowery, Madeleine M

    2014-09-01

    To evaluate the time course of fatigue in torque output and oxygen uptake during isometric subtetanic neuromuscular electrical stimulation (NMES) to facilitate the design of NMES-based rehabilitation protocols that can accumulate a defined aerobic exercise volume within a given time period. Single-arm intervention study with within-subject comparisons. University research laboratory. Volunteer sample of healthy men (N=11; mean age, 34.2 ± 11.5 y; range, 19-53 y; body mass, 79.1 ± 11.7 kg; range, 58-100 kg). A single 30-minute session of continuous bilateral isometric quadriceps NMES at 4 Hz evoking a mean twitch amplitude of 12% of the maximum voluntary contraction. Whole body oxygen consumption rate (V˙o2), and evoked torque were measured simultaneously throughout. Mean increment in V˙o2 was 596 ± 238 mL/min, and average exercise intensity during the session was 3 ±.47 metabolic equivalents. The V˙o2 and torque declined slowly at a rate of -.54%±.31% and -.47%±.57% per minute, respectively. Despite having a higher incremental V˙o2, the observed fatigue rate was considerably less than that previously reported during intermittent isometric tetanic stimulation, suggesting that subtetanic isometric NMES is more sustainable for exercise interventions aimed at accumulating a therapeutic aerobic exercise volume. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  3. Symmetric Euler orientation representations for orientational averaging.

    Science.gov (United States)

    Mayerhöfer, Thomas G

    2005-09-01

    A new kind of orientation representation called symmetric Euler orientation representation (SEOR) is presented. It is based on a combination of the conventional Euler orientation representations (Euler angles) and Hamilton's quaternions. The properties of the SEORs concerning orientational averaging are explored and compared to those of averaging schemes that are based on conventional Euler orientation representations. To that aim, the reflectance of a hypothetical polycrystalline material with orthorhombic crystal symmetry was calculated. The calculation was carried out according to the average refractive index theory (ARIT [T.G. Mayerhöfer, Appl. Spectrosc. 56 (2002) 1194]). It is shown that the use of averaging schemes based on conventional Euler orientation representations leads to a dependence of the result from the specific Euler orientation representation that was utilized and from the initial position of the crystal. The latter problem can be overcome partly by the introduction of a weighing factor, but only for two-axes-type Euler orientation representations. In case of a numerical evaluation of the average, a residual difference remains also if a two-axes type Euler orientation representation is used despite of the utilization of a weighing factor. In contrast, this problem does not occur if a symmetric Euler orientation representation is used as a matter of principle, while the result of the averaging for both types of orientation representations converges with increasing number of orientations considered in the numerical evaluation. Additionally, the use of a weighing factor and/or non-equally spaced steps in the numerical evaluation of the average is not necessary. The symmetrical Euler orientation representations are therefore ideally suited for the use in orientational averaging procedures.

  4. Aplikasi Moving Average Filter Pada Teknologi Enkripsi

    OpenAIRE

    Hermawi, Adrianto

    2007-01-01

    A method of encrypting and decrypting is introduced. The type of information experimented on is a mono wave sound file with frequency 44 KHZ. The encryption technology uses a regular noise wave sound file (with equal frequency) and moving average filter to decrypt and obtain the original signal. All experiments are programmed using MATLAB. By the end of the experiment the author concludes that the Moving Average Filter can indeed be used as an alternative to encryption technology.

  5. Average Bandwidth Allocation Model of WFQ

    Directory of Open Access Journals (Sweden)

    Tomáš Balogh

    2012-01-01

    Full Text Available We present a new iterative method for the calculation of average bandwidth assignment to traffic flows using a WFQ scheduler in IP based NGN networks. The bandwidth assignment calculation is based on the link speed, assigned weights, arrival rate, and average packet length or input rate of the traffic flows. We prove the model outcome with examples and simulation results using NS2 simulator.

  6. Knee extensor torque of men with early degrees of osteoarthritis is associated with pain, stiffness and function Homens com graus iniciais de osteoartrite apresentam correlação entre torque extensor do joelho e dor, rigidez e função

    Directory of Open Access Journals (Sweden)

    Paula R. M. S. Serrão

    2012-08-01

    Full Text Available BACKGROUND: Osteoarthritis (OA is a chronic-degenerative disease. The knee is the most commonly affected joint and the symptoms are generally attributed to quadriceps muscle weakness. However, few studies have evaluated this relationship in a population with early stages of knee OA. OBJECTIVE: To investigate whether a correlation among the knee extensor torque and the three subscales of the WOMAC questionnaire in men with early stages of knee OA exists. METHOD: Twenty-one men with knee OA grades I or II (according to Kellgren and Lawrence criteria participated in this study. The concentric and eccentric knee extensor torque were assessed using a Biodex System 3 Pro® isokinetic dynamometer, at a speed of 90º/s. Self-reported symptoms and disability were assessed using the WOMAC questionnaire. Spearman's correlation coefficient was used to test the relationship between the dependent variables (three subscales of WOMAC questionnaire and the independent variables (average knee extensor peak torque. RESULTS: We found a strong negative correlation between the concentric extensor torque and pain (r=-0.7, pCONTEXTUALIZAÇÃO: A osteoartrite (OA é uma doença crônico-degenerativa. O joelho é a articulação mais afetada, e os sintomas geralmente são atribuídos à fraqueza do músculo quadríceps. Entretanto, poucos estudos têm avaliado essa relação em indivíduos com graus iniciais de OA. OBJETIVO: Verificar se existe correlação entre o torque extensor do joelho e as seções dor, rigidez e função física do questionário WOMAC de homens com OA de joelho nos graus iniciais. MÉTODO: Participaram deste estudo 21 homens com OA de joelho graus I ou II (segundo critérios de Kelgren e Lawrence. Foi avaliado o torque extensor concêntrico e o excêntrico do joelho por meio do dinamômetro isocinético (Biodex System 3 Pro®, na velocidade de 90º/s. O autorrelato de sintomas e incapacidades foi avaliado por meio do questionário WOMAC. O

  7. Torque Teno Virus (TTV distribution in healthy Russian population

    Directory of Open Access Journals (Sweden)

    Ilinsky Valery V

    2009-09-01

    Full Text Available Abstract Background Torque teno virus (TTV is a circular, single-stranded DNA virus that chronically infects healthy individuals of all ages worldwide. There is a lot of data on the prevalence and genetic heterogeneity of TTV in healthy populations and in patients with various diseases now available. However, little is known about TTV load among healthy human population. In this study we analyzed TTV load in the group of 512 Russian elite athletes, who are supposed to be, by some standards, the healthiest part of the human population. Results The prevalence rate of TTV among the Russian Olympic Reserve members was 94% (for test sensitivity about 1000 genome equivalents per 1 ml of blood. Quantities varied from 103 (which corresponded to detection limit to 1010 copies per 1 ml of blood, with median at 2.7 × 106 copies. Conclusion About 94% of healthy individuals in Russian population have more than 1000 TTV genome copies per 1 ml of blood. This result exceeds the previously published data, and can be explained by either more sensitive PCR test system or by higher TTV distribution in Russian population or both. TTV viral load neither depends on gender, nor age.

  8. A torquing shearing interferometer for cylindrical wire array experiments.

    Science.gov (United States)

    Pikuz, S A; Schrafel, P C; Shelkovenko, T A; Kusse, B R

    2008-10-01

    In standard shearing interferometry, a single probing beam passes through a perturbing medium and is then split into two beams. A linear shift results in an overlap, an interference, and a fringe pattern yielding the perturbing medium density profile. The probing beam usually needs to be larger than the perturbing medium so that part of it passes through a well separated low density region. During early time axial (end-on) views of imploding cylindrical wire arrays low density regions lie in between the high density regions that are near the initial wire positions. In addition, for end-on viewing, the probing beam diameter is limited by electrodes and is comparable to the array diameter. In this case a linear translation will not work but the overlap can be accomplished by an azimuthal rotation of one beam with respect to the other. Such a torquing shearing interferometer has been set up on the COBRA experiment to give time resolved, radial, and azimuthal electron density profiles during early time cylindrical wire array implosions.

  9. Spin transport and spin torque in antiferromagnetic devices

    Science.gov (United States)

    Železný, J.; Wadley, P.; Olejník, K.; Hoffmann, A.; Ohno, H.

    2018-03-01

    Ferromagnets are key materials for sensing and memory applications. In contrast, antiferromagnets, which represent the more common form of magnetically ordered materials, have found less practical application beyond their use for establishing reference magnetic orientations via exchange bias. This might change in the future due to the recent progress in materials research and discoveries of antiferromagnetic spintronic phenomena suitable for device applications. Experimental demonstration of the electrical switching and detection of the Néel order open a route towards memory devices based on antiferromagnets. Apart from the radiation and magnetic-field hardness, memory cells fabricated from antiferromagnets can be inherently multilevel, which could be used for neuromorphic computing. Switching speeds attainable in antiferromagnets far exceed those of ferromagnetic and semiconductor memory technologies. Here, we review the recent progress in electronic spin-transport and spin-torque phenomena in antiferromagnets that are dominantly of the relativistic quantum-mechanical origin. We discuss their utility in pure antiferromagnetic or hybrid ferromagnetic/antiferromagnetic memory devices.

  10. Accurate measurement of microscopic forces and torques using optical tweezers

    Directory of Open Access Journals (Sweden)

    Andrew Forbes

    2011-09-01

    Full Text Available It is now well known that matter may be trapped by optical fields with high intensity gradients. Once trapped, it is then possible to manipulate microscopic particles using such optical fields, in so-called optical tweezers. Such optical trapping and tweezing systems have found widespread application across diverse fields in science, from applied biology to fundamental physics. In this article we outline the design and construction of an optical trapping and tweezing system, and show how the resulting interaction of the laser light with microscopic particles may be understood in terms of the transfer of linear and angular momentum of light. We demonstrate experimentally the use of our optical tweezing configuration for the measurement of microscopic forces and torques. In particular, we make use of digital holography to create so-called vortex laser beams, capable of transferring orbital angular momentum to particles. The use of such novel laser beams in an optical trapping and tweezing set-up allows for the control of biological species at the single-cell level.

  11. Torque coordinating robust control of shifting process for dry dual clutch transmission equipped in a hybrid car

    Science.gov (United States)

    Zhao, Z.-G.; Chen, H.-J.; Yang, Y.-Y.; He, L.

    2015-09-01

    For a hybrid car equipped with dual clutch transmission (DCT), the coordination control problems of clutches and power sources are investigated while taking full advantage of the integrated starter generator motor's fast response speed and high accuracy (speed and torque). First, a dynamic model of the shifting process is established, the vehicle acceleration is quantified according to the intentions of the driver, and the torque transmitted by clutches is calculated based on the designed disengaging principle during the torque phase. Next, a robust H∞ controller is designed to ensure speed synchronisation despite the existence of model uncertainties, measurement noise, and engine torque lag. The engine torque lag and measurement noise are used as external disturbances to initially modify the output torque of the power source. Additionally, during the torque switch phase, the torque of the power sources is smoothly transitioned to the driver's demanded torque. Finally, the torque of the power sources is further distributed based on the optimisation of system efficiency, and the throttle opening of the engine is constrained to avoid sharp torque variations. The simulation results verify that the proposed control strategies effectively address the problem of coordinating control of clutches and power sources, establishing a foundation for the application of DCT in hybrid cars.

  12. Improved averaging for non-null interferometry

    Science.gov (United States)

    Fleig, Jon F.; Murphy, Paul E.

    2013-09-01

    Arithmetic averaging of interferometric phase measurements is a well-established method for reducing the effects of time varying disturbances, such as air turbulence and vibration. Calculating a map of the standard deviation for each pixel in the average map can provide a useful estimate of its variability. However, phase maps of complex and/or high density fringe fields frequently contain defects that severely impair the effectiveness of simple phase averaging and bias the variability estimate. These defects include large or small-area phase unwrapping artifacts, large alignment components, and voids that change in number, location, or size. Inclusion of a single phase map with a large area defect into the average is usually sufficient to spoil the entire result. Small-area phase unwrapping and void defects may not render the average map metrologically useless, but they pessimistically bias the variance estimate for the overwhelming majority of the data. We present an algorithm that obtains phase average and variance estimates that are robust against both large and small-area phase defects. It identifies and rejects phase maps containing large area voids or unwrapping artifacts. It also identifies and prunes the unreliable areas of otherwise useful phase maps, and removes the effect of alignment drift from the variance estimate. The algorithm has several run-time adjustable parameters to adjust the rejection criteria for bad data. However, a single nominal setting has been effective over a wide range of conditions. This enhanced averaging algorithm can be efficiently integrated with the phase map acquisition process to minimize the number of phase samples required to approach the practical noise floor of the metrology environment.

  13. Braking due to non-resonant magnetic perturbations and comparison with neoclassical toroidal viscosity torque in EXTRAP T2R

    Science.gov (United States)

    Frassinetti, L.; Sun, Y.; Fridström, R.; Menmuir, S.; Olofsson, K. E. J.; Brunsell, P. R.; Khan, M. W. M.; Liang, Y.; Drake, J. R.

    2015-09-01

    The non-resonant magnetic perturbation (MP) braking is studied in the EXTRAP T2R reversed-field pinch (RFP) and the experimental braking torque is compared with the torque expected by the neoclassical toroidal viscosity (NTV) theory. The EXTRAP T2R active coils can apply magnetic perturbations with a single harmonic, either resonant or non-resonant. The non-resonant MP produces velocity braking with an experimental torque that affects a large part of the core region. The experimental torque is clearly related to the plasma displacement, consistent with a quadratic dependence as expected by the NTV theory. The work show a good qualitative agreement between the experimental torque in a RFP machine and NTV torque concerning both the torque density radial profile and the dependence on the non-resonant MP harmonic.

  14. The effects of imagery on fast isometric knee extensor torque development

    NARCIS (Netherlands)

    de Ruiter, C.J.; Hutter, R.I.; Icke, C; Groen, B; Gemmink, A; Smilde, H; de Haan, A.

    2012-01-01

    We hypothesized that imagery training would improve fast onset of neuromuscular activation and thereby fast knee extensor isometric torque development. Forty young healthy participants not involved in strength training, were assigned to one of four groups: physical training, imagery training,

  15. Research Update: Spin transfer torques in permalloy on monolayer MoS 2

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Sklenar, Joseph; Hsu, Bo; Jiang, Wanjun; Jungfleisch, Matthias B.; Xiao, Jiao; Fradin, Frank Y.; Liu, Yaohua; Pearson, John E.; Ketterson, John B.; Yang, Zheng; Hoffmann, Axel

    2016-03-01

    We observe current induced spin transfer torque resonance in permalloy (Py) grown on monolayer MoS2. By passing rf current through the Py/MoS2 bilayer, field-like and damping-like torques are induced which excite the ferromagnetic resonance of Py. The signals are detected via a homodyne voltage from anisotropic magnetoresistance of Py. In comparison to other bilayer systems with strong spin-orbit torques, the monolayer MoS2 cannot provide bulk spin Hall effects and thus indicates the purely interfacial nature of the spin transfer torques. Therefore our results indicate the potential of two-dimensional transition-metal dichalcogenide for the use of interfacial spin-orbitronics applications.

  16. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    Science.gov (United States)

    Khan, Asif; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-01

    A spintronic device, called the "strain assisted spin transfer torque (STT) random access memory (RAM)," is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  17. Modulation of spin transfer torque amplitude in double barrier magnetic tunnel junctions

    Science.gov (United States)

    Clément, P.-Y.; Baraduc, C.; Ducruet, C.; Vila, L.; Chshiev, M.; Diény, B.

    2015-09-01

    Magnetization switching induced by spin transfer torque is used to write magnetic memories (Magnetic Random Access Memory, MRAM) but can be detrimental to the reading process. It would be quite convenient therefore to modulate the efficiency of spin transfer torque. A solution is adding an extra degree of freedom by using double barrier magnetic tunnel junctions with two spin-polarizers, with controllable relative magnetic alignment. We demonstrate, for these structures, that the amplitude of in-plane spin transfer torque on the middle free layer can be efficiently tuned via the magnetic configuration of the electrodes. Using the proposed design could thus pave the way towards more reliable read/write schemes for MRAM. Moreover, our results suggest an intriguing effect associated with the out-of-plane (field-like) spin transfer torque, which has to be further investigated.

  18. Modulation of spin transfer torque amplitude in double barrier magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Clément, P.-Y.; Baraduc, C.; Chshiev, M.; Diény, B.; Ducruet, C.; Vila, L.

    2015-01-01

    Magnetization switching induced by spin transfer torque is used to write magnetic memories (Magnetic Random Access Memory, MRAM) but can be detrimental to the reading process. It would be quite convenient therefore to modulate the efficiency of spin transfer torque. A solution is adding an extra degree of freedom by using double barrier magnetic tunnel junctions with two spin-polarizers, with controllable relative magnetic alignment. We demonstrate, for these structures, that the amplitude of in-plane spin transfer torque on the middle free layer can be efficiently tuned via the magnetic configuration of the electrodes. Using the proposed design could thus pave the way towards more reliable read/write schemes for MRAM. Moreover, our results suggest an intriguing effect associated with the out-of-plane (field-like) spin transfer torque, which has to be further investigated

  19. Effect of resistance feedback on spin torque-induced switching of nanomagnets

    International Nuclear Information System (INIS)

    Garzon, Samir; Webb, Richard A.; Covington, Mark; Kaka, Shehzaad; Crawford, Thomas M.

    2009-01-01

    In large magnetoresistance devices spin torque-induced changes in resistance can produce GHz current and voltage oscillations which can affect magnetization reversal. In addition, capacitive shunting in large resistance devices can further reduce the current, adversely affecting spin torque switching. Here, we simultaneously solve the Landau-Lifshitz-Gilbert equation with spin torque and the transmission line telegrapher's equations to study the effects of resistance feedback and capacitance on magnetization reversal of both spin valves and magnetic tunnel junctions. While for spin valves parallel (P) to anti-parallel (AP) switching is adversely affected by the resistance feedback due to saturation of the spin torque, in low resistance magnetic tunnel junctions P-AP switching is enhanced. We study the effect of resistance feedback on the switching time of magnetic tunnel junctions, and show that magnetization switching is only affected by capacitive shunting in the pF range.

  20. Coordinated Pitch & Torque Control of Large-Scale Wind Turbine Based on Pareto Eciency Analysis

    DEFF Research Database (Denmark)

    Lin, Zhongwei; Chen, Zhenyu; Wu, Qiuwei

    2018-01-01

    to optimize the controller coordination based on the Pareto optimization theory. Three solutions are obtained through optimization, which includes the optimal torque solution, optimal power solution, and satisfactory solution. Detailed comparisons evaluate the performance of the three selected solutions...

  1. Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yuan-Yuan; Xue, Hai-Bin, E-mail: xuehaibin@tyut.edu.cn [Key Laboratory of Advanced Transducer and Intelligent Control system, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Zhe-Jie, E-mail: pandanlzj@hotmail.com [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-05-15

    We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.

  2. Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

    Directory of Open Access Journals (Sweden)

    Yuan-Yuan Guo

    2015-05-01

    Full Text Available We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.

  3. A mechanical jig for measuring ankle supination and pronation torque in vitro and in vivo.

    Science.gov (United States)

    Fong, Daniel Tik-Pui; Chung, Mandy Man-Ling; Chan, Yue-Yan; Chan, Kai-Ming

    2012-07-01

    This study presents the design of a mechanical jig for evaluating the ankle joint torque on both cadaver and human ankles. Previous study showed that ankle sprain motion was a combination of plantarflexion and inversion. The device allows measurement of ankle supination and pronation torque with one simple axis in a single step motion. More importantly, the ankle orientation allows rotation starting from an anatomical position. Six cadaveric specimens and six human subjects were tested with simulated and voluntary rotation respectively. The presented mechanical jig makes possible the determination of supination torque for studying ankle sprain injury and the estimation of pronation torque for examining peroneal muscle response. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  4. Sign Reversal of Fieldlike Spin-Orbit Torque in an Ultrathin Cr /Ni Bilayer

    Science.gov (United States)

    Bose, Arnab; Singh, Hanuman; Kushwaha, Varun Kumar; Bhuktare, Swapnil; Dutta, Sutapa; Tulapurkar, Ashwin A.

    2018-01-01

    Relativistically originated spin-orbit torque is one of the promising ways to control the magnetization dynamics of a ferromagnet, which can be useful for the next generation of spintronic memory applications. Plenty of effort has been made to address the physical origin of spin-orbit torque and improve its efficiency. In this work, we demonstrate that in ultrathin chromium/nickel (Cr /Ni ) heterostructure, spin-orbit torque is significantly enhanced for a Cr thickness below 6 nm, which is related to the possible phase change of Cr at a lower thickness. We have also observed an unconventional sign reversal of a fieldlike torque which can be attributed to the interfacial Rashba-like coupling. We experimentally obtain that approximately a 35-Oe Rashba-like magnetic field is created on 8-nm-thick in-plane magnetized Ni film when 108 A /cm2 current density flows through the Cr layer.

  5. Electric motor designs for attenuating torque disturbance in sensitive space mechanisms

    Science.gov (United States)

    Marks, David B.; Fink, Richard A.

    2003-09-01

    When a motion control system introduces unwanted torque jitter and motion anomalies into sensitive space flight optical or positioning mechanisms, the pointing accuracy, positioning capability, or scanning resolution of the mission suffers. Special motion control technology must be employed to provide attenuation of the harmful torque disturbances. Brushless DC (BLDC) Motors with low torque disturbance characteristics have been successfully used on such notable missions as the Hubble Space Telescope when conventional approaches to motor design would not work. Motor designs for low disturbance mechanisms can include two and three phase sinusoidal BLDC motors, BLDC motors without iron teeth, and sometimes skewed or non-integral slot designs for motors commutated with Hall effect devices. The principal components of motor torque disturbance, successful BLDC motor designs for attenuating disturbances, and design trade-offs for optimum performance are examined.

  6. Reducing Torque Ripples of the Axial Flux PM Motors by Magnet Stepping and Shifting

    Directory of Open Access Journals (Sweden)

    E. Cetin

    2018-02-01

    Full Text Available Higher efficiency on electric machines is the research goal of many studies. An example is the axial flux permanent magnet machines. These machines have some advantages like their watt/kg efficiency and torque density. This study aims to develop the performance characteristics of the axial flux permanent magnet machines. A new rotor magnet poles design in axial flux machines is suggested to mitigate the torque ripples. The method of stepping and shifting of the magnets is used. Two different designs are compared to verify the proposed approach. 3D finite element analysis is used for simulations. Torque ripple and back electromotive force waveforms are obtained from computer analysis. As a conclusion, the suggested method is found to be useable and mitigates the torque ripples. In addition to that, back EMF waveforms are turned to sinusoidal by the suggested design.

  7. Modulation of spin transfer torque amplitude in double barrier magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Clément, P.-Y.; Baraduc, C., E-mail: claire.baraduc@cea.fr; Chshiev, M.; Diény, B. [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, INAC-SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France); Ducruet, C. [Crocus-Technology, 5, Place Robert Schuman, F-38054 Grenoble (France); Vila, L. [Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France)

    2015-09-07

    Magnetization switching induced by spin transfer torque is used to write magnetic memories (Magnetic Random Access Memory, MRAM) but can be detrimental to the reading process. It would be quite convenient therefore to modulate the efficiency of spin transfer torque. A solution is adding an extra degree of freedom by using double barrier magnetic tunnel junctions with two spin-polarizers, with controllable relative magnetic alignment. We demonstrate, for these structures, that the amplitude of in-plane spin transfer torque on the middle free layer can be efficiently tuned via the magnetic configuration of the electrodes. Using the proposed design could thus pave the way towards more reliable read/write schemes for MRAM. Moreover, our results suggest an intriguing effect associated with the out-of-plane (field-like) spin transfer torque, which has to be further investigated.

  8. On the Torque as a Measure of Mechanical Interaction in the Principles of Dynamics

    Science.gov (United States)

    Cveticanin, Livija

    2013-01-01

    In most discussions, the Principles of Dynamics are expressed using the force as a measure of mechanical interaction between the bodies. The intention of the paper is to extend the usual discussion on basic theorems, laws and principles in Dynamics of rigid bodies including the torque as another independent measure of mechanical interaction between the bodies. In D'Alambert's principle of Dynamics, beside the forces, the active and reaction torques are also included. The torque is introduced in the Euler-Newton equations for general motion of the rigid body. The General Equation of Dynamics is reformulated by including the virtual work of the torques on the virtual rotation. An additional view to Newton's Laws is also given.

  9. Cloud-based shaft torque estimation for electric vehicle equipped with integrated motor-transmission system

    Science.gov (United States)

    Zhu, Xiaoyuan; Zhang, Hui; Yang, Bo; Zhang, Guichen

    2018-01-01

    In order to improve oscillation damping control performance as well as gear shift quality of electric vehicle equipped with integrated motor-transmission system, a cloud-based shaft torque estimation scheme is proposed in this paper by using measurable motor and wheel speed signals transmitted by wireless network. It can help reduce computational burden of onboard controllers and also relief network bandwidth requirement of individual vehicle. Considering possible delays during signal wireless transmission, delay-dependent full-order observer design is proposed to estimate the shaft torque in cloud server. With these random delays modeled by using homogenous Markov chain, robust H∞ performance is adopted to minimize the effect of wireless network-induced delays, signal measurement noise as well as system modeling uncertainties on shaft torque estimation error. Observer parameters are derived by solving linear matrix inequalities, and simulation results using acceleration test and tip-in, tip-out test demonstrate the effectiveness of proposed shaft torque observer design.

  10. Cogging Torque Reduction in a Permanent Magnet Wind Turbine Generator: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Green, J.

    2002-01-01

    In this paper, we investigate three design options to minimize cogging torque: uniformity of air gap, pole width, and skewing. Although the design improvement is intended for small wind turbines, it is also applicable to larger wind turbines.

  11. Coulomb torque - a general theory for electrostatic forces in many-body systems

    International Nuclear Information System (INIS)

    Khachatourian, Armik V M; Wistrom, Anders O

    2003-01-01

    In static experiments that comprise three conducting spheres suspended by torsion wires and held at constant electric potential, a net angular displacement about their centres has been observed. We demonstrate that the observed rotation is consistent with Coulomb's law of electrical forces complemented by Gauss' surface integrals for electrical potential. Analysis demonstrates that electrostatic torque is the result of electrostatic forces acting on an asymmetric distribution of charges residing on the surfaces of the spheres. The asymptotic value for electrostatic torque is proportional to the inverse of the fourth power of separation distance with the rotation direction, up or down taken perpendicular to a plane passing through sphere centres, given explicitly by the equation for torque. The identification of electrostatic torque prompts further analysis of models of matter at all size scales where electrostatic forces are the dominant operative force

  12. Direct Torque Control of Sensorless Induction Motor Drives: A Sliding-Mode Approach

    DEFF Research Database (Denmark)

    Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

    2004-01-01

    Direct torque control (DTC) is known to produce fast response and robust control in ac adjustable-speed drives. However, in the steady-state operation, notable torque, flux, and current pulsations occur. A new, direct torque and flux control strategy based on variable-structure control and space-vector...... pulsewidth modulation is proposed for induction motor sensorless drives. The DTC transient merits and robustness are preserved and the steady-state behaviour is improved by reducing the torque and flux pulsations. A sliding-mode observer using a dual reference frame motor model is introduced and tested....... Simulations and comparative experimental results with the proposed control scheme, versus classic DTC, are presented. Very-low-speed sensorless operation (3 r/min) is demonstrated....

  13. Cryogenic Stepping Piezomotor for Large Torque, Precise Rotary Motion Control in Passive Optics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes novel single crystal piezomotors for large torque, high precision, and cryogenic actuation with capability of position set-hold with...

  14. Angular dependence and symmetry of Rashba spin torque in ferromagnetic heterostructures

    KAUST Repository

    Ortiz Pauyac, Christian

    2013-06-26

    In a ferromagnetic heterostructure, the interplay between Rashba spin-orbit coupling and exchange splitting gives rise to a current-driven spin torque. In a realistic device setup, we investigate the Rashba spin torque in the diffusive regime and report two major findings: (i) a nonvanishing torque exists at the edges of the device even when the magnetization and effective Rashba field are aligned; (ii) anisotropic spin relaxation rates driven by the Rashba spin-orbit coupling assign the spin torque a general expression T = T y (θ) m × (y × m) + T y (θ) y × m + T z (θ) m × (z × m) + T z (θ) z × m, where the coefficients T, y, z depend on the magnetization direction. Our results agree with recent experiments. © 2013 AIP Publishing LLC.

  15. Spin-orbit-coupled transport and spin torque in a ferromagnetic heterostructure

    KAUST Repository

    Wang, Xuhui

    2014-02-07

    Ferromagnetic heterostructures provide an ideal platform to explore the nature of spin-orbit torques arising from the interplay mediated by itinerant electrons between a Rashba-type spin-orbit coupling and a ferromagnetic exchange interaction. For such a prototypic system, we develop a set of coupled diffusion equations to describe the diffusive spin dynamics and spin-orbit torques. We characterize the spin torque and its two prominent—out-of-plane and in-plane—components for a wide range of relative strength between the Rashba coupling and ferromagnetic exchange. The symmetry and angular dependence of the spin torque emerging from our simple Rashba model is in an agreement with experiments. The spin diffusion equation can be generalized to incorporate dynamic effects such as spin pumping and magnetic damping.

  16. Signatures of asymmetric and inelastic tunneling on the spin torque bias dependence

    KAUST Repository

    Manchon, Aurelien

    2010-11-15

    The influence of structural asymmetries (barrier height and exchange splitting), as well as inelastic scattering (magnons and phonons) on the bias dependence of the spin transfer torque in a magnetic tunnel junction is studied theoretically using the free-electron model. We show that they modify the “conventional” bias dependence of the spin transfer torque, together with the bias dependence of the conductance. In particular, both structural asymmetries and bulk (inelastic) scattering add antisymmetric terms to the perpendicular torque (∝V and ∝je|V|) while the interfacial inelastic scattering conserves the junction symmetry and only produces symmetric terms (∝|V|n, n∊N). The analysis of spin torque and conductance measurements displays a signature revealing the origin (asymmetry or inelastic scattering) of the discrepancy.

  17. Dirac spin-orbit torques and charge pumping at the surface of topological insulators

    KAUST Repository

    Ndiaye, Papa Birame

    2017-07-07

    We address the nature of spin-orbit torques at the magnetic surfaces of topological insulators using the linear-response theory. We find that the so-called Dirac torques in such systems possess a different symmetry compared to their Rashba counterpart, as well as a high anisotropy as a function of the magnetization direction. In particular, the damping torque vanishes when the magnetization lies in the plane of the topological-insulator surface. We also show that the Onsager reciprocal of the spin-orbit torque, the charge pumping, induces an enhanced anisotropic damping. Via a macrospin model, we numerically demonstrate that these features have important consequences in terms of magnetization switching.

  18. Research Update: Spin transfer torques in permalloy on monolayer MoS2

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2016-03-01

    Full Text Available We observe current induced spin transfer torque resonance in permalloy (Py grown on monolayer MoS2. By passing rf current through the Py/MoS2 bilayer, field-like and damping-like torques are induced which excite the ferromagnetic resonance of Py. The signals are detected via a homodyne voltage from anisotropic magnetoresistance of Py. In comparison to other bilayer systems with strong spin-orbit torques, the monolayer MoS2 cannot provide bulk spin Hall effects and thus indicates the purely interfacial nature of the spin transfer torques. Therefore our results indicate the potential of two-dimensional transition-metal dichalcogenide for the use of interfacial spin-orbitronics applications.

  19. A new direct torque control scheme for induction motors using linear state feedback

    Energy Technology Data Exchange (ETDEWEB)

    Kandianis, A.; Manias, S.N. [National Technical Univ. of Athens (Greece). Dept. of Electrical Engineering; Griva, G.; Profumo, F. [Politecnico di Torino (Italy). Dept. of Electrical Engineering

    1995-12-31

    In this paper a new Direct Torque Control (DTC) scheme for induction motor drives is described, based on the linear state feedback method with dynamic output feedback. The DTC has been shown to be a good solution in torque controlled drives applications when the speed control is not required (e.g. traction drives for electric vehicles). In such cases, the torque command comes directly from the user input. By considering the torque and flux as the outputs of the linearized motor model, it is possible to design an optimum controller with constant gain state feedback and dynamic output feedback through an integral term. The design procedure of the proposed control scheme is described and the simulation results are presented to show the overall performance of the system.

  20. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    International Nuclear Information System (INIS)

    Khan, Asif; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-01-01

    A spintronic device, called the “strain assisted spin transfer torque (STT) random access memory (RAM),” is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.