Sample records for joint torque patterns
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Influence of Joint Angle on EMG-Torque Model During Constant-Posture, Torque-Varying Contractions.
Liu, Pu; Liu, Lukai; Clancy, Edward A
2015-11-01
Relating the electromyogram (EMG) to joint torque is useful in various application areas, including prosthesis control, ergonomics and clinical biomechanics. Limited study has related EMG to torque across varied joint angles, particularly when subjects performed force-varying contractions or when optimized modeling methods were utilized. We related the biceps-triceps surface EMG of 22 subjects to elbow torque at six joint angles (spanning 60° to 135°) during constant-posture, torque-varying contractions. Three nonlinear EMG σ -torque models, advanced EMG amplitude (EMG σ ) estimation processors (i.e., whitened, multiple-channel) and the duration of data used to train models were investigated. When EMG-torque models were formed separately for each of the six distinct joint angles, a minimum "gold standard" error of 4.01±1.2% MVC(F90) resulted (i.e., error relative to maximum voluntary contraction at 90° flexion). This model structure, however, did not directly facilitate interpolation across angles. The best model which did so achieved a statistically equivalent error of 4.06±1.2% MVC(F90). Results demonstrated that advanced EMG σ processors lead to improved joint torque estimation as do longer model training durations.
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Towards Scalable Strain Gauge-Based Joint Torque Sensors
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
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Space Suit Joint Torque Testing
Valish, Dana J.
2011-01-01
In 2009 and early 2010, a test was performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design meets the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future space suits. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis and a variance in torque values for some of the tested joints was apparent. Potential variables that could have affected the data were identified and re-testing was conducted in an attempt to eliminate these variables. The results of the retest will be used to determine if further testing and modification is necessary before the method can be validated.
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Results and Analysis from Space Suit Joint Torque Testing
Matty, Jennifer
2010-01-01
This joint mobility KC lecture included information from two papers, "A Method for and Issues Associated with the Determination of Space Suit Joint Requirements" and "Results and Analysis from Space Suit Joint Torque Testing," as presented for the International Conference on Environmental Systems in 2009 and 2010, respectively. The first paper discusses historical joint torque testing methodologies and approaches that were tested in 2008 and 2009. The second paper discusses the testing that was completed in 2009 and 2010.
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How joint torques affect hamstring injury risk in sprinting swing-stance transition.
Sun, Yuliang; Wei, Shutao; Zhong, Yunjian; Fu, Weijie; Li, Li; Liu, Yu
2015-02-01
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. 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. 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. 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.
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Integrated High-Speed Torque Control System for a Robotic Joint
Davis, Donald R. (Inventor); Radford, Nicolaus A. (Inventor); Permenter, Frank Noble (Inventor); Valvo, Michael C. (Inventor); Askew, R. Scott (Inventor)
2013-01-01
A control system for achieving high-speed torque for a joint of a robot includes a printed circuit board assembly (PCBA) having a collocated joint processor and high-speed communication bus. The PCBA may also include a power inverter module (PIM) and local sensor conditioning electronics (SCE) for processing sensor data from one or more motor position sensors. Torque control of a motor of the joint is provided via the PCBA as a high-speed torque loop. Each joint processor may be embedded within or collocated with the robotic joint being controlled. Collocation of the joint processor, PIM, and high-speed bus may increase noise immunity of the control system, and the localized processing of sensor data from the joint motor at the joint level may minimize bus cabling to and from each control node. The joint processor may include a field programmable gate array (FPGA).
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How Joint Torques Affect Hamstring Injury Risk in Sprinting Swing–Stance Transition
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
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真鍋, 芳明; 横澤, 俊治; 島田, 一志; 尾縣, 貢
2004-01-01
The purpose of this study was to compare joint torque and the activity pattern of eight muscles crossing the ankle, knee and hip joints during three kinds of squats with different speeds (Slow, Normal, Quick). Ten male athletes performed squats at three different speeds. Variables such as net torque and power about the joint were calculated during the descending and ascending phase of each squat. At the same time, surface electrodes were placed over the eight lower extremity muscles,.and %iEM...
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Hahn, Daniel; Herzog, Walter; Schwirtz, Ansgar
2014-08-01
Force and torque production of human muscles depends upon their lengths and contraction velocity. However, these factors are widely assumed to be independent of each other and the few studies that dealt with interactions of torque, angle and angular velocity are based on isolated single-joint movements. Thus, the purpose of this study was to determine force/torque-angle and force/torque-angular velocity properties for multi-joint leg extensions. Human leg extension was investigated (n = 18) on a motor-driven leg press dynamometer while measuring external reaction forces at the feet. Extensor torque in the knee joint was calculated using inverse dynamics. Isometric contractions were performed at eight joint angle configurations of the lower limb corresponding to increments of 10° at the knee from 30 to 100° of knee flexion. Concentric and eccentric contractions were performed over the same range of motion at mean angular velocities of the knee from 30 to 240° s(-1). For contractions of increasing velocity, optimum knee angle shifted from 52 ± 7 to 64 ± 4° knee flexion. Furthermore, the curvature of the concentric force/torque-angular velocity relations varied with joint angles and maximum angular velocities increased from 866 ± 79 to 1,238 ± 132° s(-1) for 90-50° knee flexion. Normalised eccentric forces/torques ranged from 0.85 ± 0.12 to 1.32 ± 0.16 of their isometric reference, only showing significant increases above isometric and an effect of angular velocity for joint angles greater than optimum knee angle. The findings reveal that force/torque production during multi-joint leg extension depends on the combined effects of angle and angular velocity. This finding should be accounted for in modelling and optimisation of human movement.
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Fatigue affects peak joint torque angle in hamstrings but not in quadriceps.
Coratella, Giuseppe; Bellin, Giuseppe; Beato, Marco; Schena, Federico
2015-01-01
Primary aim of this study was to investigate peak joint torque angle (i.e. the angle of peak torque) changes recorded during an isokinetic test before and after a fatiguing soccer match simulation. Secondarily we want to investigate functional Hecc:Qconc and conventional Hconc:Qconc ratio changes due to fatigue. Before and after a standardised soccer match simulation, twenty-two healthy male amateur soccer players performed maximal isokinetic strength tests both for hamstrings and for quadriceps muscles at 1.05 rad · s(‒1), 3.14 rad · s(‒1) and 5.24 rad · s(‒1). Peak joint torque angle, peak torque and both functional Hecc:Qconc and conventional Hconc:Qconc ratios were examined. Both dominant and non-dominant limbs were tested. Peak joint torque angle significantly increased only in knee flexors. Both eccentric and concentric contractions resulted in such increment, which occurred in both limbs. No changes were found in quadriceps peak joint torque angle. Participants experienced a significant decrease in torque both in hamstrings and in quadriceps. Functional Hecc:Qconc ratio was lower only in dominant limb at higher velocities, while Hconc:Qconc did not change. This study showed after specific fatiguing task changes in hamstrings only torque/angle relationship. Hamstrings injury risk could depend on altered torque when knee is close to extension, coupled with a greater peak torque decrement compared to quadriceps. These results suggest the use eccentric based training to prevent hamstrings shift towards shorter length.
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Space Suit Joint Torque Measurement Method Validation
Valish, Dana; Eversley, Karina
2012-01-01
In 2009 and early 2010, a test method was developed and performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits. This was done in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design met the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future development programs. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis; the results indicated a significant variance in values reported for a subset of the re-tested joints. Potential variables that could have affected the data were identified and a third round of testing was conducted in an attempt to eliminate and/or quantify the effects of these variables. The results of the third test effort will be used to determine whether or not the proposed joint torque methodology can be applied to future space suit development contracts.
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Fricke, S.S.; Dragunas, Andrew C.; Gordon, Keith E.; van der Kooij, H.; van Asseldonk, E.H.F.; Dewald, Julius P. A.
Motor impairments following stroke may lead to a reduced walking ability, however, no reliable assessments to quantify these impairments during walking are available [1]. For example, abnormal joint torque coupling between hip extension and hip adduction, previously reported under isometric
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Sukal-Moulton, Theresa; Krosschell, Kristin J; Gaebler-Spira, Deborah J; Dewald, Julius P A
2014-01-01
Extensive neuromotor development occurs early in human life, and the timing of brain injury may affect the resulting motor impairment. In Part I of this series, it was demonstrated that the distribution of weakness in the upper extremity depended on the timing of brain injury in individuals with childhood-onset hemiparesis. The goal of this study was to characterize how timing of brain injury affects joint torque synergies, or losses of independent joint control. Twenty-four individuals with hemiparesis were divided into 3 groups based on the timing of their injury: before birth (PRE-natal, n = 8), around the time of birth (PERI-natal, n = 8), and after 6 months of age (POST-natal, n = 8). Individuals with hemiparesis and 8 typically developing peers participated in maximal isometric shoulder, elbow, wrist, and finger torque generation tasks while their efforts were recorded by a multiple degree-of-freedom load cell. Motor output in 4 joints of the upper extremity was concurrently measured during 8 primary torque generation tasks to quantify joint torque synergies. There were a number of significant coupling patterns identified in individuals with hemiparesis that differed from the typically developing group. POST-natal differences were most noted in the coupling of shoulder abductors with elbow, wrist, and finger flexors, while the PRE-natal group demonstrated significant distal joint coupling with elbow flexion. The torque synergies measured provide indirect evidence for the use of bulbospinal pathways in the POST-natal group, while those with earlier injury may use relatively preserved ipsilateral corticospinal motor pathways.
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Joint forces and torques when walking in shallow water.
Orselli, Maria Isabel Veras; Duarte, Marcos
2011-04-07
This study reports for the first time an estimation of the internal net joint forces and torques on adults' lower limbs and pelvis when walking in shallow water, taking into account the drag forces generated by the movement of their bodies in the water and the equivalent data when they walk on land. A force plate and a video camera were used to perform a two-dimensional gait analysis at the sagittal plane of 10 healthy young adults walking at comfortable speeds on land and in water at a chest-high level. We estimated the drag force on each body segment and the joint forces and torques at the ankle, knee, and hip of the right side of their bodies using inverse dynamics. The observed subjects' apparent weight in water was about 35% of their weight on land and they were about 2.7 times slower when walking in water. When the subjects walked in water compared with walking on land, there were no differences in the angular displacements but there was a significant reduction in the joint torques which was related to the water's depth. The greatest reduction was observed for the ankle and then the knee and no reduction was observed for the hip. All joint powers were significantly reduced in water. The compressive and shear joint forces were on average about three times lower during walking in water than on land. These quantitative results substantiate the use of water as a safe environment for practicing low-impact exercises, particularly walking. Copyright © 2011 Elsevier Ltd. All rights reserved.
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Hip joint torques during the golf swing of young and senior healthy males.
Foxworth, Judy L; Millar, Audrey L; Long, Benjamin L; Way, Michael; Vellucci, Matthew W; Vogler, Joshua D
2013-09-01
Descriptive, laboratory study. To compare the 3-D hip torques during a golf swing between young and senior healthy male amateur golfers. The secondary purpose was to compare the 3-D hip joint torques between the trail leg and lead leg. The generation of hip torques from the hip musculature is an important aspect of the golf swing. Golf is a very popular activity, and estimates of hip torques during the golf swing have not been reported. Twenty healthy male golfers were divided into a young group (mean ± SD age, 25.1 ± 3.1 years) and a senior group (age, 56.9 ± 4.7 years). All subjects completed 10 golf swings using their personal driver. A motion capture system and force plates were used to obtain kinematic and kinetic data. Inverse dynamic analyses were used to calculate 3-D hip joint torques of the trail and lead limbs. Two-way analyses of covariance (group by leg), with club-head velocity as a covariate, were used to compare peak hip torques between groups and limbs. Trail-limb hip external rotator torque was significantly greater in the younger group compared to the senior group, and greater in the trail leg versus the lead leg. When adjusting for club-head velocity, young and senior healthy male amateur golfers generated comparable hip torques during a golf swing, with the exception of the trail-limb hip external rotator torque. The largest hip torque found was the trail-limb hip extensor torque.
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Comparison of joint torque evoked with monopolar and tripolar-cuff electrodes.
Tarler, Matthew D; Mortimer, J Thomas
2003-09-01
Using a self-sizing spiral-cuff electrode placed on the sciatic nerve of the cat, the joint torque evoked with stimulation applied to contacts in a monopolar configuration was judged to be the same as the torque evoked by stimulation applied to contacts in a tripolar configuration. Experiments were carried out in six acute cat preparations. In each experiment, a 12-contact electrode was placed on the sciatic nerve and used to effect both the monopolar and tripolar electrode configurations. The ankle torque produced by electrically evoked isometric muscle contraction was measured in three dimensions: plantar flexion, internal rotation, and inversion. Based on the recorded ankle torque, qualitative and quantitative comparisons were performed to determine if any significant difference existed in the pattern or order in which motor nerve fibers were recruited. No significant difference was found at a 98% confidence interval in either the recruitment properties or the repeatability of the monopolar and tripolar configurations. Further, isolated activation of single fascicles within the sciatic nerve was observed. Once nerve fibers in a fascicle were activated, recruitment of that fascicle was modulated over the full range before "spill-over" excitation occurred in neighboring fascicles. These results indicate that a four contact, monopolar nerve-cuff electrode is a viable substitute for a 12 contact, tripolar nerve-cuff electrode. The results of this study are also consistent with the hypothesis that multicontact self-sizing spiral-cuff electrodes can be used in motor prostheses to provide selective control of many muscles. These findings should also apply to other neuroprostheses employing-cuff electrodes on nerve trunks.
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Biscarini, Andrea; Botti, Fabio M; Pettorossi, Vito E
2013-02-01
We developed a biomechanical model to determine the joint torques and loadings during squatting with a backward/forward-inclined Smith machine. The Smith squat allows a large variety of body positioning (trunk tilt, foot placement, combinations of joint angles) and easy control of weight distribution between forefoot and heel. These distinctive aspects of the exercise can be managed concurrently with the equipment inclination selected to unload specific joint structures while activating specific muscle groups. A backward (forward) equipment inclination decreases (increases) knee torque, and compressive tibiofemoral and patellofemoral forces, while enhances (depresses) hip and lumbosacral torques. For small knee flexion angles, the strain-force on the posterior cruciate ligament increases (decreases) with a backward (forward) equipment inclination, whereas for large knee flexion angles, this behavior is reversed. In the 0 to 60 degree range of knee flexion angles, loads on both cruciate ligaments may be simultaneously suppressed by a 30 degree backward equipment inclination and selecting, for each value of the knee angle, specific pairs of ankle and hip angles. The anterior cruciate ligament is safely maintained unloaded by squatting with backward equipment inclination and uniform/forward foot weight distribution. The conditions for the development of anterior cruciate ligament strain forces are clearly explained.
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Dynamic modeling and optimal joint torque coordination of advanced robotic systems
Kang, Hee-Jun
The development is documented of an efficient dynamic modeling algorithm and the subsequent optimal joint input load coordination of advanced robotic systems for industrial application. A closed-form dynamic modeling algorithm for the general closed-chain robotic linkage systems is presented. The algorithm is based on the transfer of system dependence from a set of open chain Lagrangian coordinates to any desired system generalized coordinate set of the closed-chain. Three different techniques for evaluation of the kinematic closed chain constraints allow the representation of the dynamic modeling parameters in terms of system generalized coordinates and have no restriction with regard to kinematic redundancy. The total computational requirement of the closed-chain system model is largely dependent on the computation required for the dynamic model of an open kinematic chain. In order to improve computational efficiency, modification of an existing open-chain KIC based dynamic formulation is made by the introduction of the generalized augmented body concept. This algorithm allows a 44 pct. computational saving over the current optimized one (O(N4), 5995 when N = 6). As means of resolving redundancies in advanced robotic systems, local joint torque optimization is applied for effectively using actuator power while avoiding joint torque limits. The stability problem in local joint torque optimization schemes is eliminated by using fictitious dissipating forces which act in the necessary null space. The performance index representing the global torque norm is shown to be satisfactory. In addition, the resulting joint motion trajectory becomes conservative, after a transient stage, for repetitive cyclic end-effector trajectories. The effectiveness of the null space damping method is shown. The modular robot, which is built of well defined structural modules from a finite-size inventory and is controlled by one general computer system, is another class of evolving
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Gymnasts and non-athletes muscle activation and torque production at the ankle joint
Directory of Open Access Journals (Sweden)
Natália Batista Albuquerque Goulart
2014-07-01
Full Text Available http://dx.doi.org/10.5007/1980-0037.2014v16n5p555 Artistic Gymnasts (AG execute specific movements that require substantial movement control and force production at the ankle joint. This high demand might change the neuromechanical properties of the ankle joint muscles in these athletes compared to non-athlete girls (NAG. The aim of this study was to compare muscle activation and torque production at the ankle joint between AG and NAG. Ten AG (11.70 ± 1.06 years of age and 10 NAG (11.70 ± 1.49 years of age participated in the study. Electromyographic (EMG signals of medial gastrocnemius (MG, soleus (SO and tibialis anterior (TA were obtained simultaneously to the maximal isometric plantarflexion (PFT and dorsiflexion (DFT torques of the dominant limb during a maximal voluntary isometric contraction (MVIC at five different joint angles (20°, 10°, 0°, -10° e -20°. Neuromuscular efficiency was also calculated by the Torque/EMG ratio. AG presented higher PFT (p0.05. In addition, AG showed higher values for plantar flexion neuromuscular efficiency and smaller values of dorsiflexion neuromuscular efficiency compared to the NAG (p<0.01. Higher sports demands of AG determined higher PFT, higher plantar flexor efficiency, smaller DFT but similar activation of MG, SO and TA compared to NAG.
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Directory of Open Access Journals (Sweden)
Saeed Nikoukheslat
2016-06-01
Full Text Available Objective: The aim of this study was to investigate the relationship between isokinetic relative torques of hip, knee and ankle joints and the height of guide leg jump in young men. Methods: 27 college male athletes with mean age of 25±3.5 years, height 178.5±7.8 cm and weight of 75.7±10.7 kg voluntarily participated in this study. Isokinetic torque of hip, knee and ankle joints and the height of vertical jump were measured using BIODEX SYSTEM PRO 4 and digital vertical jumping tester systems respectively. Pearson correlation test at p<0.05 was used for statistical analysis. Results: Results showed that there were significant correlations between height of jump and hip joint flexion (p= 0.047 & r= 0.39 and extension (p= 0.003 & r= 0.55 torques of guide leg, hip joint extension torque of support leg (p= 0.020 & r=0.45 and knee joint flexion (p= 0.019 & r=0.45 and extension torques of support leg (p=0.006 & r=0.52. Conclusion: The results of this study show that flexion and extension torques of hip joint in guide leg and knee joint in support leg and also extension torque of hip joint in support leg have main effect on height of guide leg jump. Thus, in designing a specific training program for athletes in whom the nature of jump in their sports is guide leg jump, particular attention should be given to hip and knee joints strength.
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Removal Torque and Biofilm Accumulation at Two Dental Implant-Abutment Joints After Fatigue.
Pereira, Jorge; Morsch, Carolina S; Henriques, Bruno; Nascimento, Rubens M; Benfatti, Cesar Am; Silva, Filipe S; López-López, José; Souza, Júlio Cm
2016-01-01
The aim of this study was to evaluate the removal torque and in vitro biofilm penetration at Morse taper and hexagonal implant-abutment joints after fatigue tests. Sixty dental implants were divided into two groups: (1) Morse taper and (2) external hexagon implant-abutment systems. Fatigue tests on the implant-abutment assemblies were performed at a normal force (FN) of 50 N at 1.2 Hz for 500,000 cycles in growth medium containing human saliva for 72 hours. Removal torque mean values (n = 10) were measured after fatigue tests. Abutments were then immersed in 1% protease solution in order to detach the biofilms for optical density and colony-forming unit (CFU/cm²) analyses. Groups of implant-abutment assemblies (n = 8) were cross-sectioned at 90 degrees relative to the plane of the implant-abutment joints for the microgap measurement by field-emission guns scanning electron microscopy. Mean values of removal torque on abutments were significantly lower for both Morse taper (22.1 ± 0.5 μm) and external hexagon (21.1 ± 0.7 μm) abutments after fatigue tests than those recorded without fatigue tests (respectively, 24 ± 0.5 μm and 24.8 ± 0.6 μm) in biofilm medium for 72 hours (P = .04). Mean values of microgap size for the Morse taper joints were statistically signicantly lower without fatigue tests (1.7 ± 0.4 μm) than those recorded after fatigue tests (3.2 ± 0.8 μm). Also, mean values of microgap size for external hexagon joints free of fatigue were statistically signicantly lower (1.5 ± 0.4 μm) than those recorded after fatigue tests (8.1 ± 1.7 μm) (P abutments (Abs630nm at 0.06 and 2.9 × 10⁴ CFU/cm²) than that on external hexagon abutments (Abs630nm at 0.08 and 4.5 × 10⁴ CFU/cm²) (P = .01). The mean values of removal torque, microgap size, and biofilm density recorded at Morse taper joints were lower in comparison to those recorded at external hexagon implant-abutment joints after fatigue tests in a simulated oral environment for 72 hours.
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Schrade, Stefan O; Nager, Yannik; Wu, Amy R; Gassert, Roger; Ijspeert, Auke
2017-07-01
Robotic lower limb exoskeletons are becoming increasingly popular in therapy and recreational use. However, most exoskeletons are still rather limited in their locomotion speed and the activities of daily live they can perform. Furthermore, they typically do not allow for a dynamic adaptation to the environment, as they are often controlled with predefined reference trajectories. Inspired by human leg stiffness modulation during walking, variable stiffness actuators increase flexibility without the need for more complex controllers. Actuation with adaptable stiffness is inspired by the human leg stiffness modulation during walking. However, this actuation principle also introduces the stiffness setpoint as an additional degree of freedom that needs to be coordinated with the joint trajectories. As a potential solution to this issue a bio-inspired controller based on a central pattern generator (CPG) is presented in this work. It generates coordinated joint torques and knee stiffness modulations to produce flexible and dynamic gait patterns for an exoskeleton with variable knee stiffness actuation. The CPG controller is evaluated and optimized in simulation using a model of the exoskeleton. The CPG controller produced stable and smooth gait for walking speeds from 0.4 m/s up to 1.57 m/s with a torso stabilizing force that simulated the use of crutches, which are commonly needed by exoskeleton users. Through the CPG, the knee stiffness intrinsically adapted to the frequency and phase of the gait, when the speed was changed. Additionally, it adjusted to changes in the environment in the form of uneven terrain by reacting to ground contact forces. This could allow future exoskeletons to be more adaptive to various environments, thus making ambulation more robust.
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宮西, 智久; Tomohisa, Miyanishi; 仙台大学; Sendai College
1998-01-01
In sports biomechanics, joint torque analysis play a very important role. For this reason, if we understand the joint torque during sports activity, it will be useful for the diagnosis and/or evaluation of sports technique, the specific method for muscle training and the mechanisms of sports movement. In the past decade, many studies which dealt with the motion analysis for sports activity using a three-dimensional cinematography, have been done. However, most of these studies has been focuse...
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Directory of Open Access Journals (Sweden)
Menon Carlo
2011-09-01
Full Text Available Abstract Background Several regression models have been proposed for estimation of isometric joint torque using surface electromyography (SEMG signals. Common issues related to torque estimation models are degradation of model accuracy with passage of time, electrode displacement, and alteration of limb posture. This work compares the performance of the most commonly used regression models under these circumstances, in order to assist researchers with identifying the most appropriate model for a specific biomedical application. Methods Eleven healthy volunteers participated in this study. A custom-built rig, equipped with a torque sensor, was used to measure isometric torque as each volunteer flexed and extended his wrist. SEMG signals from eight forearm muscles, in addition to wrist joint torque data were gathered during the experiment. Additional data were gathered one hour and twenty-four hours following the completion of the first data gathering session, for the purpose of evaluating the effects of passage of time and electrode displacement on accuracy of models. Acquired SEMG signals were filtered, rectified, normalized and then fed to models for training. Results It was shown that mean adjusted coefficient of determination (Ra2 values decrease between 20%-35% for different models after one hour while altering arm posture decreased mean Ra2 values between 64% to 74% for different models. Conclusions Model estimation accuracy drops significantly with passage of time, electrode displacement, and alteration of limb posture. Therefore model retraining is crucial for preserving estimation accuracy. Data resampling can significantly reduce model training time without losing estimation accuracy. Among the models compared, ordinary least squares linear regression model (OLS was shown to have high isometric torque estimation accuracy combined with very short training times.
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Effects of hand grip exercise on shoulder joint internal rotation and external rotation peak torque.
Lee, Dong-Rour; Jong-Soon Kim, Laurentius
2016-08-10
The goal of this study is to analyze the effects of hand grip training on shoulder joint internal rotation (IR)/external rotation (ER) peak torque for healthy people. The research was conducted on 23 healthy adults in their 20 s-30 s who volunteered to participate in the experiment. Hand grip power test was performed on both hands of the research subjects before/after the test to study changes in hand grip power. Isokinetic machine was used to measure the concentric IRPT (internal rotation peak torque) and concentric ERPT (external rotation peak torque) at the velocity of 60°/sec, 90°/sec, and 180°/sec before/after the test. Hand grip training was performed daily on the subject's right hand only for four weeks according to exercise program. Finally, hand grip power of both hands and the maximum torque values of shoulder joint IR/ER were measured before/after the test and analyzed. There was a statistically significant difference in the hand grip power of the right hand, which was subject to hand grip training, after the experiment. Also, statistically significant difference for shoulder ERPT was found at 60°/sec. Hand grip training has a positive effect on shoulder joint IRPT/ERPT and therefore can help strengthen muscles around the shoulder without using weight on the shoulder. Consequently, hand grip training would help maintain strengthen the muscles around the shoulder in the early phase of rehabilitation process after shoulder surgery.
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Modelling the joint torques and loadings during squatting at the Smith machine.
Biscarini, Andrea; Benvenuti, Paolo; Botti, Fabio; Mastrandrea, Francesco; Zanuso, Silvano
2011-03-01
An analytical biomechanical model was developed to establish the relevant properties of the Smith squat exercise, and the main differences from the free barbell squat. The Smith squat may be largely patterned to modulate the distributions of muscle activities and joint loadings. For a given value of the included knee angle (θ(knee)), bending the trunk forward, moving the feet forward in front of the knees, and displacing the weight distribution towards the forefoot emphasizes hip and lumbosacral torques, while also reducing knee torque and compressive tibiofemoral and patellofemoral forces (and vice versa). The tibiofemoral shear force φ(t) displays more complex trends that strongly depend on θ(knee). Notably, for 180° ≥ θ(knee) ≥ 130°, φ(t) and cruciate ligament strain forces can be suppressed by selecting proper pairs of ankle and hip angles. Loading of the posterior cruciate ligament increases (decreases) in the range 180° ≥ θ(knee) ≥ 150° (θ(knee) ≤ 130°) with knee extension, bending the trunk forward, and moving the feet forward in front of the knees. In the range 150° > θ(knee) > 130°, the behaviour changes depending on the foot weight distribution. The conditions for the development of anterior cruciate ligament strain forces are explained. This work enables careful use of the Smith squat in strengthening and rehabilitation programmes.
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Yoo, Won-Gyu
2015-01-01
[Purpose] We investigated the effects of individual strengthening exercises for the stabilization muscles on the nutation torque of the sacroiliac joint in a sedentary worker with nonspecific sacroiliac joint pain. [Subject] A 36-year-old female complained of pain in the sacroiliac joints. [Methods] The subject performed individual strengthening exercises for the stabilization muscles for nutation torque of the sacroiliac joint for 3 weeks. Pain-provocation tests and visual analog scale (VAS) scores were evaluated before and after the exercises. [Results] After performing the individual strengthening exercises for the erector spinae, rectus abdominis, and biceps femoris muscles for 3 weeks, the subject displayed no pain in the pain provocation tests, and the VAS score was 2/10. [Conclusion] The individual strengthening exercises for the stabilization muscles of the sacroiliac joint performed in the present study appear to be effective for sedentary workers with sacroiliac joint pain.
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Ding, Yang; Ming, Tingyu
2016-11-01
In undulatory locomotion, torque (bending moment) is required along the body to overcome the external forces from environments and bend the body. Previous observations on animals using less than two wavelengths on the body showed such torque has a single traveling wave pattern. Using resistive force theory model and considering the torque generated by external force in a resistive force dominated media, we found that as the wave number (number of wavelengths on the locomotor's body) increases from 0.5 to 1.8, the speed of the traveling wave of torque decreases. When the wave number increases to 2 and greater, the torque pattern transits from a single traveling wave to a two traveling waves and then a complex pattern that consists two wave-like patterns. By analyzing the force distribution and its contribution to the torque, we explain the speed decrease of the torque wave and the pattern transition. This research is partially supported by the Recruitment Program of Global Young Experts (China).
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Interaction torque contributes to planar reaching at slow speed
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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
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Liu, Feng; Williams, Sophie; Jin, Zhongmin; Fisher, John
2013-11-01
Head contact on the rim of the cup causes stress concentration and consequently increased wear. The head contact on the rim of the cup may in addition cause an offset load and torque on the cup. The head-rim contact resulting from microseparation or subluxation has been investigated. An analytical model has been developed to calculate the offset loading and resultant torque on the cup as a function of the translational displacement of the head under simplified loading condition of the hip joint at heel strike during a walking cycle. The magnitude of the torque on the cup was found to increase with the increasing translational displacement, larger diameter heads, eccentric cups, and the coefficient of friction of the contact. The effects of cup inclination, cup rim radius, and cup coverage angle on the magnitude of the torque were found to be relatively small with a maximum variation in the torque magnitude being lower than 20%. This study has shown an increased torque due to the head loading on the rim of the cup, and this may contribute to the incidence of cup loosening. Particularly, metal-on-metal hip joints with larger head diameters may produce the highest offset loading torque.
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Felipe Pivetta Carpes
2012-06-01
Full Text Available Extensively unilateral recruitment for daily activities may determine performance asymmetries in favor of the preferred side eliciting functional adaptation. Our study evaluated asymmetries in elbow torque output between preferred and non-preferred limbs. Eighteen subjects performed maximal elbow flexor and extensor isometric contractions at five different elbow joint angles (0º, 30º, 60º, 90º, 120º and five different angular velocities (60, 120, 180, 240, 300º.s-1 on an isokinetic dynamometer. Higher flexor torque in favor of preferred arm was observed at 90º of flexion (pO frequente recrutamento unilateral de membros superiores pode determinar assimetrias de desempenho em favor do lado preferido, resultando em adaptação funcional. Assimetrias no torque gerado pelos músculos do cotovelo entre o membro preferido e não-preferido foram avaliadas. Dezoito sujeitos realizaram contrações máximas de flexo-extensão do cotovelo em cinco ângulos articulares (0º, 30º, 60º, 90º, 120º e cinco velocidades angulares (60, 120, 180, 240, 300º.s-1 em um dinamômetro isocinético. Torque flexor mais elevado em favor do lado preferido foi encontrado no ângulo de 90º (p<0,05, que também correspondeu ao ângulo de maior torque (p<0,05. O fato de o ângulo articular determinar assimetrias no torque (enquanto a velocidade angular não sugere que o recrutamento preferencial dos flexores do cotovelo em um ângulo de 90º nas tarefas da vida diária que requerem força elevada é responsável pela assimetria. Adaptação funcional a estímulos frequentes nesse ângulo articular pode explicar esses resultados em sujeitos saudáveis.
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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.
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A Method to Accurately Estimate the Muscular Torques of Human Wearing Exoskeletons by Torque Sensors
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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.
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Applied Joint-Space Torque and Stiffness Control of Tendon-Driven Fingers
Abdallah, Muhammad E.; Platt, Robert, Jr.; Wampler, Charles W.; Hargrave, Brian
2010-01-01
Existing tendon-driven fingers have applied force control through independent tension controllers on each tendon, i.e. in the tendon-space. The coupled kinematics of the tendons, however, cause such controllers to exhibit a transient coupling in their response. This problem can be resolved by alternatively framing the controllers in the joint-space of the manipulator. This work presents a joint-space torque control law that demonstrates both a decoupled and significantly faster response than an equivalent tendon-space formulation. The law also demonstrates greater speed and robustness than comparable PI controllers. In addition, a tension distribution algorithm is presented here to allocate forces from the joints to the tendons. It allocates the tensions so that they satisfy both an upper and lower bound, and it does so without requiring linear programming or open-ended iterations. The control law and tension distribution algorithm are implemented on the robotic hand of Robonaut-2.
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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.
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Spinal circuits can accommodate interaction torques during multijoint limb movements.
Buhrmann, Thomas; Di Paolo, Ezequiel A
2014-01-01
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.
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Spinal circuits can accommodate interaction torques during multijoint limb movements
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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.
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Andrade, R J; Freitas, S R; Vaz, J R; Bruno, P M; Pezarat-Correia, P
2015-06-01
This study aimed to determine the influence of the head, upper trunk, and foot position on the passive knee extension (PKE) torque-angle response. PKE tests were performed in 10 healthy subjects using an isokinetic dynamometer at 2°/s. Subjects lay in the supine position with their hips flexed to 90°. The knee angle, passive torque, surface electromyography (EMG) of the semitendinosus and quadriceps vastus medialis, and stretch discomfort were recorded in six body positions during PKE. The different maximal active positions of the cervical spine (neutral; flexion; extension), thoracic spine (neutral; flexion), and ankle (neutral; dorsiflexion) were passively combined for the tests. Visual analog scale scores and EMG were unaffected by body segment positioning. An effect of the ankle joint was verified on the peak torque and knee maximum angle when the ankle was in the dorsiflexion position (P torque (P torque when the cervical and thoracic spines were flexed (P torque-angle response since different positions of head, upper trunk, and foot induce dissimilar knee mechanical responses during passive extension. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Limited Angle Torque Motors Having High Torque Density, Used in Accurate Drive Systems
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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.
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Peak torque and rate of torque development in elderly with and without fall history.
Bento, Paulo Cesar Barauce; Pereira, Gleber; Ugrinowitsch, Carlos; Rodacki, André Luiz Felix
2010-06-01
Falls are one of the greatest concerns among the elderly. A number of studies have described peak torque as one of the best fall-related predictor. No studies have comprehensively focused on the rate of torque development of the lower limb muscles among elderly fallers. Then, the aim of this study was to determine the relationship between muscle peak torque and rate of torque development of the lower limb joints in elderly with and without fall history. It was also aimed to determine whether these parameters of muscle performance (i.e., peak torque and rate of torque development) are related to the number of falls. Thirty-one women volunteered to participate in the study and were assigned in one of the groups according to the number of falls over the 12 months that preceded the present. Then, participants with no fall history (GI; n=13; 67.6[7.5] years-old), one fall (GII; n=8; 66.0[4.9] years-old) and two or more falls (GIII; n=10; 67.8[8.8] years-old) performed a number of lower limb maximal isometric voluntary contractions from which peak torque and rate of torque development were quantified. Primary outcomes indicated no peak torque differences between experimental groups in any lower limb joint. The rate of torque development of the knee flexor muscles observed in the non-fallers (GI) was greater than that observed in the fallers (Pfalls (Pelderly to rapidly reorganise the arrangement of the lower limb may play a significant role in allowing the elderly to recover balance after a trip. Thus, training stimulus aimed to improve the rate of torque development may be more beneficial to prevent falls among the elderly than other training stimulus, which are not specifically designed to improve the ability to rapidly produce large amounts of torque. Copyright (c) 2010. Published by Elsevier Ltd.
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Pelvic rotation torque during fast-pitch softball hitting under three ball height conditions.
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.
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Moltedo, Marta; Bacek, Tomislav; Langlois, Kevin; Junius, Karen; Vanderborght, Bram; Lefeber, Dirk
2017-07-01
The human ankle joint plays a crucial role during walking. At the push-off phase the ankle plantarflexors generate the highest torque among the lower limb joints during this activity. The potential of the ankle plantarflexors is affected by numerous pathologies and injuries, which cause a decrease in the ability of the subject to achieve a natural gait pattern. Active orthoses have shown to have potential in assisting these subjects. The design of such robots is very challenging due to the contrasting design requirements of wearability (light weight and compact) and high torques capacity. This paper presents the development of a high-torque ankle actuator to assist the ankle joint in both dorsiflexion and plantarflexion. The compliant actuator is a spindle-driven MACCEPA (Mechanically Adjustable Compliance and Controllable Equilibrium Position Actuator). The design of the actuator was made to keep its weight as low as possible, while being able to provide high torques. As a result of this novel design, the actuator weighs 1.18kg. Some static characterization tests were perfomed on the actuator and their results are shown in the paper.
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Torque control of underactuated tendon-driven fingers
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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. -
Andersson, J K; Axelsson, P; Strömberg, J; Karlsson, J; Fridén, J
2016-09-01
A total of 20 patients scheduled for wrist arthroscopy, all with clinical signs of rupture to the triangular fibrocartilage complex and distal radioulnar joint instability, were tested pre-operatively by an independent observer for strength of forearm rotation. During surgery, the intra-articular pathology was documented by photography and also subsequently individually analysed by another independent hand surgeon. Arthroscopy revealed a type 1-B injury to the triangular fibrocartilage complex in 18 of 20 patients. Inter-rater reliability between the operating surgeon and the independent reviewer showed absolute agreement in all but one patient (95%) in terms of the injury to the triangular fibrocartilage complex and its classification. The average pre-operative torque strength was 71% of the strength of the non-injured contralateral side in pronation and supination. Distal radioulnar joint instability with an arthroscopically verified injury to the triangular fibrocartilage complex is associated with a significant loss of both pronation and supination torque. Case series, Level IV. © The Author(s) 2015.
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KNEE ISOKINETIC TORQUE IMBALANCE IN FEMALE FUTSAL PLAYERS
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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.
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Development and evaluation of a musculoskeletal model of the elbow joint complex
Gonzalez, Roger V.; Hutchins, E. L.; Barr, Ronald E.; Abraham, Lawrence D.
1993-01-01
This paper describes the development and evaluation of a musculoskeletal model that represents human elbow flexion-extension and forearm pronation-supination. The length, velocity, and moment arm for each of the eight musculotendon actuators were based on skeletal anatomy and position. Musculotendon parameters were determined for each actuator and verified by comparing analytical torque-angle curves with experimental joint torque data. The parameters and skeletal geometry were also utilized in the musculoskeletal model for the analysis of ballistic elbow joint complex movements. The key objective was to develop a computational model, guided by parameterized optimal control, to investigate the relationship among patterns of muscle excitation, individual muscle forces, and movement kinematics. The model was verified using experimental kinematic, torque, and electromyographic data from volunteer subjects performing ballistic elbow joint complex movements.
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Fujii, Keisuke; Yamashita, Daichi; Kimura, Tetsuya; Isaka, Tadao; Kouzaki, Motoki
2015-01-01
In a competitive sport, the outcome of a game is determined by an athlete's relationship with an unpredictable and uncontrolled opponent. We have previously analyzed the preparatory state of ground reaction forces (GRFs) dividing non-weighted and weighted states (i.e., vertical GRFs below and above 120% of body weight, respectively) in a competitive ballgame task and demonstrated that the non-weighted state prevented delay of the defensive step and promoted successful guarding. However, the associated kinetics of lower extremity joints during a competitive sports task remains unknown. The present study aims to investigate the kinetic characteristics of a real-time competitive sport before movement initiation. As a first kinetic study on a competitive sport, we initially compared the successful defensive kinetics with a relatively stable preparatory state and the choice-reaction sidestep as a control movement. Then, we investigated the kinetic cause of the outcome in a 1-on-1 dribble in terms of the preparatory states according to our previous study. The results demonstrated that in successful defensive motions in the non-weighted state guarding trial, the times required for the generation of hip abduction and three extension torques for the hip, knee, and ankle joints were significantly shortened compared with the choice-reaction sidestep, and hip abduction and hip extension torques were produced almost simultaneously. The sport-specific movement kinetics emerges only in a more-realistic interactive experimental setting. A comparison of the outcomes in the 1-on-1 dribble and preparatory GRF states showed that, in the non-weighted state, the defenders guarded successfully in 68.0% of the trials, and the defender's initiation time was earlier than that in the weighted state (39.1%). In terms of kinetics, the root mean squares of the derivative of hip abduction and three extension torques in the non-weighted state were smaller than those in the weighted state
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In Vivo Measurement of Glenohumeral Joint Contact Patterns
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Bey MichaelJ
2010-01-01
Full Text Available The objectives of this study were to describe a technique for measuring in-vivo glenohumeral joint contact patterns during dynamic activities and to demonstrate application of this technique. The experimental technique calculated joint contact patterns by combining CT-based 3D bone models with joint motion data that were accurately measured from biplane x-ray images. Joint contact patterns were calculated for the repaired and contralateral shoulders of 20 patients who had undergone rotator cuff repair. Significant differences in joint contact patterns were detected due to abduction angle and shoulder condition (i.e., repaired versus contralateral. Abduction angle had a significant effect on the superior/inferior contact center position, with the average joint contact center of the repaired shoulder 12.1% higher on the glenoid than the contralateral shoulder. This technique provides clinically relevant information by calculating in-vivo joint contact patterns during dynamic conditions and overcomes many limitations associated with conventional techniques for quantifying joint mechanics.
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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.
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Deliberate utilization of interaction torques brakes elbow extension in a fast throwing motion.
Hore, Jon; Debicki, Derek B; Gribble, Paul L; Watts, Sherry
2011-05-01
We tested the hypothesis that in fast arm movements the CNS deliberately utilizes interaction torques to decelerate (brake) joint rotations. Twelve subjects performed fast 2-D overarm throws in which large elbow extension velocities occurred. Joint motions were computed from recordings made with search coils; joint torques were calculated using inverse dynamics. After ball release, a large follow-through shoulder extension acceleration occurred that was initiated by shoulder extensor muscle torque. This shoulder acceleration produced a flexor interaction torque at the elbow that initiated elbow deceleration (braking). An instantaneous mechanical interaction of passive torques then occurred between elbow and shoulder, i.e., elbow extension deceleration produced a large shoulder extensor interaction torque that contributed to the shoulder extension acceleration which, simultaneously, produced a large elbow flexor interaction torque that contributed to elbow extension deceleration, and so on. Late elbow flexor muscle torque also contributed to elbow deceleration. The interaction of passive torques between shoulder and elbow was braked by shoulder flexor muscle torque. In this mechanism, shoulder musculature contributed to braking elbow extension in two ways: shoulder extensors initiated the mechanical interaction of passive torques between shoulder and elbow and shoulder flexors dissipated kinetic energy from elbow braking. It is concluded that, in fast 2-D throws, the CNS deliberately utilizes powerful interaction torques between shoulder and elbow to brake motion at the elbow.
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International Nuclear Information System (INIS)
Hara, Takaaki; Senami, Masato; Tachibana, Akitomo
2012-01-01
The spin torque and zeta force, which govern spin dynamics, are studied by using monoatoms in their steady states. We find nonzero local spin torque in transition metal atoms, which is in balance with the counter torque, the zeta force. We show that d-orbital electrons have a crucial effect on these torques. Nonzero local chirality density in transition metal atoms is also found, though the electron mass has the effect to wash out nonzero chirality density. Distribution patterns of the chirality density are the same for Sc–Ni atoms, though the electron density distributions are different. -- Highlights: ► Nonzero local spin torque is found in the steady states of transition metal atoms. ► The spin steady state is realized by the existence of a counter torque, zeta force. ► D-orbital electrons have a crucial effect on the spin torque and zeta force. ► Nonzero local chiral density is found in spite of the washout by the electron mass. ► Chiral density distribution have the same pattern for Sc–Ni atoms.
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The Positive Benefits of Negative Movement Patterns Following Total Knee Arthroplasty.
Christensen, Jesse C; Foreman, K Bo; LaStayo, Paul C
2018-01-01
Eccentric (negative) resistance exercise of the legs using specialized machines has been reported to be useful and often superior to standard exercise following total knee arthroplasty (TKA). Movements that utilize body mass and gravity as a mode of eccentric resistance exercise in a more pragmatic rehabilitation paradigm may also be useful in reversing chronic muscle impairments observed years following surgery. This study explores whether an eccentrically biased, body mass resistance exercise induces greater magnitude of sagittal plane extensor angular impulse of the support torque and individual net joint torque contributions during both squatting and lunging movement patterns 6 weeks following TKA. Cross-sectional laboratory-based study design including 10 patients following primary unilateral TKA (6.5 ± 0.8 weeks.). All patients completed 3 trials of the squat and lunge movement pattern under both a concentric and an eccentric condition. Extensor angular impulse of the support torque and net joint torque contributions were calculated by integrating the joint torque versus time curves. A Two-way analysis of covariance was conducted and contracts of clinical interest were computed using Wald posttest. P Values for all pairwise comparisons were adjusted for multiplicity using Bonferroni multiple comparison procedure. The eccentric condition, compared to the concentric condition, displayed larger magnitude of extensor angular impulse during both the squat ( P movement patterns for the support torques. Similarly, the eccentric condition, compared to the concentric condition, displayed larger magnitude of extensor angular impulse of the hip, knee, and ankle ( P movement patterns. Eccentrically biased, body mass movement exercises can produce higher levels of extensor angular impulse on the surgical limb in patients early after TKA. Patients in this study were able to tolerate the higher extensor angular impulse demands and performed the eccentrically biased
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Torque Control of Underactuated Tendon-driven Robotic Fingers
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.
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Independent control of joint stiffness in the framework of the equilibrium-point hypothesis.
Latash, M L
1992-01-01
In the framework of the equilibrium-point hypothesis, virtual trajectories and joint stiffness patterns have been reconstructed during two motor tasks practiced against a constant bias torque. One task required a voluntary increase in joint stiffness while preserving the original joint position. The other task involved fast elbow flexions over 36 degrees. Joint stiffness gradually subsided after the termination of fast movements. In both tasks, the external torque could slowly and unexpectedly change. The subjects were required not to change their motor commands if the torque changed, i.e. "to do the same no matter what the motor did". In both tasks, changes in joint stiffness were accompanied by unchanged virtual trajectories that were also independent of the absolute value of the bias torque. By contrast, the intercept of the joint compliant characteristic with the angle axis, r(t)-function, has demonstrated a clear dependence upon both the level of coactivation and external load. We assume that a template virtual trajectory is generated at a certain level of the motor hierarchy and is later scaled taking into account some commonly changing dynamic factors of the movement execution, for example, external load. The scaling leads to the generation of commands to the segmental structures that can be expressed, according to the equilibrium-point hypothesis, as changes in the thresholds of the tonic stretch reflex for corresponding muscles.
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Torque Control of a Rehabilitation Teaching Robot Using Magneto-Rheological Fluid Clutches
Hakogi, Hokuto; Ohaba, Motoyoshi; Kuramochi, Naimu; Yano, Hidenori
A new robot that makes use of MR-fluid clutches for simulating torque is proposed to provide an appropriate device for training physical therapy students in knee-joint rehabilitation. The feeling of torque provided by the robot is expected to correspond to the torque performance obtained by physical therapy experts in a clinical setting. The torque required for knee-joint rehabilitation, which is a function of the rotational angle and the rotational angular velocity of a knee movement, is modeled using a mechanical system composed of typical spring-mass-damper elements. The robot consists of two MR-fluid clutches, two induction motors, and a feedback control system. In the torque experiments, output torque is controlled using the spring and damper coefficients separately. The values of these coefficients are determined experimentally. The experimental results show that the robot would be suitable for training physical therapy students to experience similar torque feelings as needed in a clinical situation.
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Biomechanical design of escalading lower limb exoskeleton with novel linkage joints.
Zhang, Guoan; Liu, Gangfeng; Ma, Sun; Wang, Tianshuo; Zhao, Jie; Zhu, Yanhe
2017-07-20
In this paper, an obstacle-surmounting-enabled lower limb exoskeleton with novel linkage joints that perfectly mimicked human motions was proposed. Currently, most lower exoskeletons that use linear actuators have a direct connection between the wearer and the controlled part. Compared to the existing joints, the novel linkage joint not only fitted better into compact chasis, but also provided greater torque when the joint was at a large bend angle. As a result, it extended the angle range of joint peak torque output. With any given power, torque was prioritized over rotational speed, because instead of rotational speed, sufficiency of torque is the premise for most joint actions. With insufficient torque, the exoskeleton will be a burden instead of enhancement to its wearer. With optimized distribution of torque among the joints, the novel linkage method may contribute to easier exoskeleton movements.
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Directory of Open Access Journals (Sweden)
Alex Pitti
2009-10-01
Full Text Available Pattern generators found in the spinal cords are no more seen as simple rhythmic oscillators for motion control. Indeed, they achieve flexible and dynamical coordination in interaction with the body and the environment dynamics to rise motor synergies. Discovering the mechanisms underlying the control of motor synergies constitute an important research question not only for neuroscience but also for robotics: the motors coordination of high dimensional robotic systems is still a drawback and new control methods based on biological solutions may reduce their overall complexity. We propose to model the flexible combination of motor synergies in embodied systems via partial phase synchronization of distributed chaotic systems; for specific coupling strength, chaotic systems are able to phase synchronize their dynamics to the resonant frequencies of one external force. We take advantage of this property to explore and exploit the intrinsic dynamics of one specified embodied system. In two experiments with bipedal walkers, we show how motor synergies emerge when the controllers phase synchronize to the body’s dynamics, entraining it to its intrinsic behavioral patterns. This stage is characterized by directed information flow from the sensors to the motors exhibiting the optimal situation when the body dynamics drive the controllers (mutual entrainment. Based on our results, we discuss the relevance of our findings for modeling the modular control of distributed pattern generators exhibited in the spinal cords, and for exploring the motor synergies in robots.
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Space suit glove design with advanced metacarpal phalangeal joints and robotic hand evaluation.
Southern, Theodore; Roberts, Dustyn P; Moiseev, Nikolay; Ross, Amy; Kim, Joo H
2013-06-01
One area of space suits that is ripe for innovation is the glove. Existing models allow for some fine motor control, but the power grip--the act of grasping a bar--is cumbersome due to high torque requirements at the knuckle or metacarpal phalangeal joint (MCP). This area in particular is also a major source of complaints of pain and injury as reported by astronauts. This paper explores a novel fabrication and patterning technique that allows for more freedom of movement and less pain at this crucial joint in the manned space suit glove. The improvements are evaluated through unmanned testing, manned testing while depressurized in a vacuum glove box, and pressurized testing with a robotic hand. MCP joint flex score improved from 6 to 6.75 (out of 10) in the final glove relative to the baseline glove, and torque required for flexion decreased an average of 17% across all fingers. Qualitative assessments during unpressurized and depressurized manned testing also indicated the final glove was more comfortable than the baseline glove. The quantitative results from both human subject questionnaires and robotic torque evaluation suggest that the final iteration of the glove design enables flexion at the MCP joint with less torque and more comfort than the baseline glove.
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Movement coordination patterns between the foot joints during walking
Directory of Open Access Journals (Sweden)
John B. Arnold
2017-10-01
Full Text Available Abstract Background In 3D gait analysis, kinematics of the foot joints are usually reported via isolated time histories of joint rotations and no information is provided on the relationship between rotations at different joints. The aim of this study was to identify movement coordination patterns in the foot during walking by expanding an existing vector coding technique according to an established multi-segment foot and ankle model. A graphical representation is also described to summarise the coordination patterns of joint rotations across multiple patients. Methods Three-dimensional multi-segment foot kinematics were recorded in 13 adults during walking. A modified vector coding technique was used to identify coordination patterns between foot joints involving calcaneus, midfoot, metatarsus and hallux segments. According to the type and direction of joints rotations, these were classified as in-phase (same direction, anti-phase (opposite directions, proximal or distal joint dominant. Results In early stance, 51 to 75% of walking trials showed proximal-phase coordination between foot joints comprising the calcaneus, midfoot and metatarsus. In-phase coordination was more prominent in late stance, reflecting synergy in the simultaneous inversion occurring at multiple foot joints. Conversely, a distal-phase coordination pattern was identified for sagittal plane motion of the ankle relative to the midtarsal joint, highlighting the critical role of arch shortening to locomotor function in push-off. Conclusions This study has identified coordination patterns between movement of the calcaneus, midfoot, metatarsus and hallux by expanding an existing vector cording technique for assessing and classifying coordination patterns of foot joints rotations during walking. This approach provides a different perspective in the analysis of multi-segment foot kinematics, and may be used for the objective quantification of the alterations in foot joint
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Callahan, Damien M.; Umberger, Brian R.; Kent-Braun, Jane A.
2013-01-01
The pathway of voluntary joint torque production includes motor neuron recruitment and rate-coding, sarcolemmal depolarization and calcium release by the sarcoplasmic reticulum, force generation by motor proteins within skeletal muscle, and force transmission by tendon across the joint. The direct source of energetic support for this process is ATP hydrolysis. It is possible to examine portions of this physiologic pathway using various in vivo and in vitro techniques, but an integrated view of the multiple processes that ultimately impact joint torque remains elusive. To address this gap, we present a comprehensive computational model of the combined neuromuscular and musculoskeletal systems that includes novel components related to intracellular bioenergetics function. Components representing excitatory drive, muscle activation, force generation, metabolic perturbations, and torque production during voluntary human ankle dorsiflexion were constructed, using a combination of experimentally-derived data and literature values. Simulation results were validated by comparison with torque and metabolic data obtained in vivo. The model successfully predicted peak and submaximal voluntary and electrically-elicited torque output, and accurately simulated the metabolic perturbations associated with voluntary contractions. This novel, comprehensive model could be used to better understand impact of global effectors such as age and disease on various components of the neuromuscular system, and ultimately, voluntary torque output. PMID:23405245
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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.
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Mechanics of Re-Torquing in Bolted Flange Connections
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
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Tracking control of time-varying knee exoskeleton disturbed by interaction torque.
Li, Zhan; Ma, Wenhao; Yin, Ziguang; Guo, Hongliang
2017-11-01
Knee exoskeletons have been increasingly applied as assistive devices to help lower-extremity impaired people to make their knee joints move through providing external movement compensation. Tracking control of knee exoskeletons guided by human intentions often encounters time-varying (time-dependent) issues and the disturbance interaction torque, which may dramatically put an influence up on their dynamic behaviors. Inertial and viscous parameters of knee exoskeletons can be estimated to be time-varying due to unexpected mechanical vibrations and contact interactions. Moreover, the interaction torque produced from knee joint of wearers has an evident disturbance effect on regular motions of knee exoskeleton. All of these points can increase difficultly of accurate control of knee exoskeletons to follow desired joint angle trajectories. This paper proposes a novel control strategy for controlling knee exoskeleton with time-varying inertial and viscous coefficients disturbed by interaction torque. Such designed controller is able to make the tracking error of joint angle of knee exoskeletons exponentially converge to zero. Meanwhile, the proposed approach is robust to guarantee the tracking error bounded when the interaction torque exists. Illustrative simulation and experiment results are presented to show efficiency of the proposed controller. Additionally, comparisons with gradient dynamic (GD) approach and other methods are also presented to demonstrate efficiency and superiority of the proposed control strategy for tracking joint angle of knee exoskeleton. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
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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.
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Directory of Open Access Journals (Sweden)
Hiroyuki NAKAMOTO
2007-04-01
Full Text Available Various humanoid robots have been developed and multifunction robot hands which are able to attach those robots like human hand is needed. But a useful robot hand has not been depeveloped, because there are a lot of problems such as control method of many degrees of freedom and processing method of enormous sensor outputs. Realizing such robot hand, we have developed five-finger robot hand. In this paper, the detailed structure of developed robot hand is described. The robot hand we developed has five fingers of multi-joint that is equipped with joint torque sensors and tactile sensors. We report experimental results of a stiffness control with the developed robot hand. Those results show that it is possible to change the stiffness of joints. Moreover we propose an object recognition method with the tactile sensor. The validity of that method is assured by experimental results.
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Respiratory pattern changes during costovertebral joint movement.
Shannon, R
1980-05-01
Experiments were conducted to determine if costovertebral joint manipulation (CVJM) could influence the respiratory pattern. Phrenic efferent activity (PA) was monitored in dogs that were anesthetized with Dial-urethane, vagotomized, paralyzed, and artificially ventilated. Ribs 6-10 (bilaterally) were cut and separated from ribs 5-11. Branches of thoracic nerves 5-11 were cut, leaving only the joint nerve supply intact. Manual joint movement in an inspiratory or expiratory direction had an inhibitory effect on PA. Sustained displacement of the ribs could inhibit PA for a duration equal to numerous respiratory cycles. CVJM in synchrony with PA resulted in an increased respiratory rate. The inspiratory inhibitory effect of joint receptor stimulation was elicited with manual chest compression in vagotomized spontaneously breathing dogs, but not with artificial lung inflation or deflation. It is concluded that the effect of CVJM on the respiratory pattern is due to stimulation of joint mechanoreceptors, and that they exert their influence in part via the medullary-pontine rhythm generator.
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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.
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Arshad, Mahnaz; Mahgoli, Hosseinali; Payaminia, Leila
To evaluate the effect of repeated screw joint closing and opening cycles and cyclic loading on abutment screw removal torque and screw thread morphology using scanning electron microscopy (SEM). Three groups (n = 10 in each group) of implant-abutment-abutment screw assemblies were created. There were also 10 extra abutment screws as new screws in group 3. The abutment screws were tightened to 12 Ncm with an electronic torque meter; then they were removed and removal torque values were recorded. This sequence was repeated 5 times for group 1 and 15 times for groups 2 and 3. The same screws in groups 1 and 2 and the new screws in group 3 were then tightened to 12 Ncm; this was also followed by screw tightening to 30 Ncm and retightening to 30 Ncm 15 minutes later. Removal torque measurements were performed after screws were subjected to cyclic loading (0.5 × 10⁶ cycles; 1 Hz; 75 N). Moreover, the surface topography of one screw from each group before and after cyclic loading was evaluated with SEM and compared with an unused screw. All groups exhibited reduced removal torque values in comparison to insertion torque in each cycle. However, there was a steady trend of torque loss in each group. A comparison of the last cycle of the groups before loading showed significantly greater torque loss value in the 15th cycle of groups 2 and 3 compared with the fifth cycle of group 1 (P abutment is definitively placed.
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Dounskaia, Natalia; Shimansky, Yury
2016-06-01
Optimality criteria underlying organization of arm movements are often validated by testing their ability to adequately predict hand trajectories. However, kinematic redundancy of the arm allows production of the same hand trajectory through different joint coordination patterns. We therefore consider movement optimality at the level of joint coordination patterns. A review of studies of multi-joint movement control suggests that a 'trailing' pattern of joint control is consistently observed during which a single ('leading') joint is rotated actively and interaction torque produced by this joint is the primary contributor to the motion of the other ('trailing') joints. A tendency to use the trailing pattern whenever the kinematic redundancy is sufficient and increased utilization of this pattern during skillful movements suggests optimality of the trailing pattern. The goal of this study is to determine the cost function minimization of which predicts the trailing pattern. We show that extensive experimental testing of many known cost functions cannot successfully explain optimality of the trailing pattern. We therefore propose a novel cost function that represents neural effort for joint coordination. That effort is quantified as the cost of neural information processing required for joint coordination. We show that a tendency to reduce this 'neurocomputational' cost predicts the trailing pattern and that the theoretically developed predictions fully agree with the experimental findings on control of multi-joint movements. Implications for future research of the suggested interpretation of the trailing joint control pattern and the theory of joint coordination underlying it are discussed.
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A model to explain joint patterns found in ignimbrite deposits
Tibaldi, A.; Bonali, F. L.
2018-03-01
The study of fracture systems is of paramount importance for economic applications, such as CO2 storage in rock successions, geothermal and hydrocarbon exploration and exploitation, and also for a better knowledge of seismogenic fault formation. Understanding the origin of joints can be useful for tectonic studies and for a geotechnical characterisation of rock masses. Here, we illustrate a joint pattern discovered in ignimbrite deposits of South America, which can be confused with conjugate tectonic joint sets but which have another origin. The pattern is probably common, but recognisable only in plan view and before tectonic deformation obscures and overprints it. Key sites have been mostly studied by field surveys in Bolivia and Chile. The pattern is represented by hundreds-of-meters up to kilometre-long swarms of master joints, which show circular to semi-circular geometries and intersections that have "X" and "Y" patterns. Inside each swarm, joints are systematic, rectilinear or curvilinear in plan view, and as much as 900 m long. In section view, they are from sub-vertical to vertical and do not affect the underlying deposits. Joints with different orientation mostly interrupt each other, suggesting they have the same age. This joint architecture is here interpreted as resulting from differential contraction after emplacement of the ignimbrite deposit above a complex topography. The set of the joint pattern that has suitable orientation with respect to tectonic stresses may act to nucleate faults.
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Ibitoye, Morufu Olusola; Hamzaid, Nur Azah; Hasnan, Nazirah; Abdul Wahab, Ahmad Khairi; Islam, Md Anamul; Kean, Victor S P; Davis, Glen M
2016-08-01
The interaction between muscle contractions and joint loading produces torques necessary for movements during activities of daily living. However, during neuromuscular electrical stimulation (NMES)-evoked contractions in persons with spinal cord injury (SCI), a simple and reliable proxy of torque at the muscle level has been minimally investigated. Thus, the purpose of this study was to investigate the relationships between muscle mechanomyographic (MMG) characteristics and NMES-evoked isometric quadriceps torques in persons with motor complete SCI. Six SCI participants with lesion levels below C4 [(mean (SD) age, 39.2 (7.9) year; stature, 1.71 (0.05) m; and body mass, 69.3 (12.9) kg)] performed randomly ordered NMES-evoked isometric leg muscle contractions at 30°, 60° and 90° knee flexion angles on an isokinetic dynamometer. MMG signals were detected by an accelerometer-based vibromyographic sensor placed over the belly of rectus femoris muscle. The relationship between MMG root mean square (MMG-RMS) and NMES-evoked torque revealed a very high association (R(2)=0.91 at 30°; R(2)=0.98 at 60°; and R(2)=0.97 at 90° knee angles; Ptorque, between 0.65 and 0.79 for MMG-RMS, and from 0.67 to 0.73 for MMG-PTP. Their standard error of measurements (SEM) ranged between 10.1% and 31.6% (of mean values) for torque, MMG-RMS and MMG-PTP. The MMG peak frequency (MMG-PF) of 30Hz approximated the stimulation frequency, indicating NMES-evoked motor unit firing rate. The results demonstrated knee angle differences in the MMG-RMS versus NMES-isometric torque relationship, but a similar torque related pattern for MMG-PF. These findings suggested that MMG was well associated with torque production, reliably tracking the motor unit recruitment pattern during NMES-evoked muscle contractions. The strong positive relationship between MMG signal and NMES-evoked torque production suggested that the MMG might be deployed as a direct proxy for muscle torque or fatigue measurement during
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Spin-wave interference patterns created by spin-torque nano-oscillators for memory and computation
International Nuclear Information System (INIS)
Macia, Ferran; Kent, Andrew D; Hoppensteadt, Frank C
2011-01-01
Magnetization dynamics in nanomagnets has attracted broad interest since it was predicted that a dc current flowing through a thin magnetic layer can create spin-wave excitations. These excitations are due to spin momentum transfer, a transfer of spin angular momentum between conduction electrons and the background magnetization, that enables new types of information processing. Here we show how arrays of spin-torque nano-oscillators can create propagating spin-wave interference patterns of use for memory and computation. Memristic transponders distributed on the thin film respond to threshold tunnel magnetoresistance values, thereby allowing spin-wave detection and creating new excitation patterns. We show how groups of transponders create resonant (reverberating) spin-wave interference patterns that may be used for polychronous wave computation and information storage.
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Kordi, Mehdi; Goodall, Stuart; Barratt, Paul; Rowley, Nicola; Leeder, Jonathan; Howatson, Glyn
2017-08-01
From a cycling paradigm, little has been done to understand the relationships between maximal isometric strength of different single joint lower body muscle groups and their relation with, and ability to predict PPO and how they compare to an isometric cycling specific task. The aim of this study was to establish relationships between maximal voluntary torque production from isometric single-joint and cycling specific tasks and assess their ability to predict PPO. Twenty male trained cyclists participated in this study. Peak torque was measured by performing maximum voluntary contractions (MVC) of knee extensors, knee flexors, dorsi flexors and hip extensors whilst instrumented cranks measured isometric peak torque from MVC when participants were in their cycling specific position (ISOCYC). A stepwise regression showed that peak torque of the knee extensors was the only significant predictor of PPO when using SJD and accounted for 47% of the variance. However, when compared to ISOCYC, the only significant predictor of PPO was ISOCYC, which accounted for 77% of the variance. This suggests that peak torque of the knee extensors was the best single-joint predictor of PPO in sprint cycling. Furthermore, a stronger prediction can be made from a task specific isometric task. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Orion - Super Koropon(Registered Trademark) Torque/Tension Report
Hemminger, Edgar G.; McLeod, Christopher; Peil, John
2012-01-01
The primary objective of this testing was to obtain torque tension data for the use of Super Koropon Primer Base which was proposed for use on the Orion project. This compound is a corrosion inhibitor/sealer used on threaded fasteners and inserts as specified per NASA/JSC PRC-4004, Sealing of Joints and Faying Surfaces. Some secondary objectives of this testing, were to identify the effect on torque coefficient of several variables. This document contains the outcome of the testing.
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Estimation of Electrically-Evoked Knee Torque from Mechanomyography Using Support Vector Regression
Directory of Open Access Journals (Sweden)
Morufu Olusola Ibitoye
2016-07-01
Full Text Available The difficulty of real-time muscle force or joint torque estimation during neuromuscular electrical stimulation (NMES in physical therapy and exercise science has motivated recent research interest in torque estimation from other muscle characteristics. This study investigated the accuracy of a computational intelligence technique for estimating NMES-evoked knee extension torque based on the Mechanomyographic signals (MMG of contracting muscles that were recorded from eight healthy males. Simulation of the knee torque was modelled via Support Vector Regression (SVR due to its good generalization ability in related fields. Inputs to the proposed model were MMG amplitude characteristics, the level of electrical stimulation or contraction intensity, and knee angle. Gaussian kernel function, as well as its optimal parameters were identified with the best performance measure and were applied as the SVR kernel function to build an effective knee torque estimation model. To train and test the model, the data were partitioned into training (70% and testing (30% subsets, respectively. The SVR estimation accuracy, based on the coefficient of determination (R2 between the actual and the estimated torque values was up to 94% and 89% during the training and testing cases, with root mean square errors (RMSE of 9.48 and 12.95, respectively. The knee torque estimations obtained using SVR modelling agreed well with the experimental data from an isokinetic dynamometer. These findings support the realization of a closed-loop NMES system for functional tasks using MMG as the feedback signal source and an SVR algorithm for joint torque estimation.
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Joint contact loading in forefoot and rearfoot strike patterns during running.
Rooney, Brandon D; Derrick, Timothy R
2013-09-03
Research concerning forefoot strike pattern (FFS) versus rearfoot strike pattern (RFS) running has focused on the ground reaction force even though internal joint contact forces are a more direct measure of the loads responsible for injury. The main purpose of this study was to determine the internal loading of the joints for each strike pattern. A secondary purpose was to determine if converted FFS and RFS runners can adequately represent habitual runners with regards to the internal joint loading. Using inverse dynamics to calculate the net joint moments and reaction forces and optimization techniques to estimate muscle forces, we determined the axial compressive loading at the ankle, knee, and hip. Subjects consisted of 15 habitual FFS and 15 habitual RFS competitive runners. Each subject ran at a preferred running velocity with their habitual strike pattern and then converted to the opposite strike pattern. Plantar flexor muscle forces and net ankle joint moments were greater in the FFS running compared to the RFS running during the first half of the stance phase. The average contact forces during this period increased by 41.7% at the ankle and 14.4% at the knee joint during FFS running. Peak ankle joint contact force was 1.5 body weights greater during FFS running (pstrike pattern. Copyright © 2013 Elsevier Ltd. All rights reserved.
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EMG-Torque correction on Human Upper extremity using Evolutionary Computation
JL, Veronica; Parasuraman, S.; Khan, M. K. A. Ahamed; Jeba DSingh, Kingsly
2016-09-01
There have been many studies indicating that control system of rehabilitative robot plays an important role in determining the outcome of the therapy process. Existing works have done the prediction of feedback signal in the controller based on the kinematics parameters and EMG readings of upper limb's skeletal system. Kinematics and kinetics based control signal system is developed by reading the output of the sensors such as position sensor, orientation sensor and F/T (Force/Torque) sensor and there readings are to be compared with the preceding measurement to decide on the amount of assistive force. There are also other works that incorporated the kinematics parameters to calculate the kinetics parameters via formulation and pre-defined assumptions. Nevertheless, these types of control signals analyze the movement of the upper limb only based on the movement of the upper joints. They do not anticipate the possibility of muscle plasticity. The focus of the paper is to make use of the kinematics parameters and EMG readings of skeletal system to predict the individual torque of upper extremity's joints. The surface EMG signals are fed into different mathematical models so that these data can be trained through Genetic Algorithm (GA) to find the best correlation between EMG signals and torques acting on the upper limb's joints. The estimated torque attained from the mathematical models is called simulated output. The simulated output will then be compared with the actual individual joint which is calculated based on the real time kinematics parameters of the upper movement of the skeleton when the muscle cells are activated. The findings from this contribution are extended into the development of the active control signal based controller for rehabilitation robot.
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Ankle rehabilitation device with two degrees of freedom and compliant joint
Racu (Cazacu, C.-M.; Doroftei, I.
2015-11-01
We propose a rehabilitation device that we intend to be low cost and easy to manufacture. The system will ensure functionality but also have a small dimensions and low mass, considering the physiological dimensions of the foot and lower leg. To avoid injure of the ankle joint, this device is equipped with a compliant joint between the motor and mechanical transmission. The torque of this joint is intended to be adjustable, according to the degree of ankle joint damage. To choose the material and the dimensions of this compliant joint, in this paper we perform the first stress simulation. The minimum torque is calculated, while the maximum torque is given by the preliminary chosen actuator.
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Influence of the implant-abutment connection design and diameter on the screw joint stability
Shin, Hyon-Mo; Huh, Jung-Bo; Yun, Mi-Jeong; Jeon, Young-Chan; Chang, Brian Myung
2014-01-01
PURPOSE This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (α=0.05). RESULTS The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate. PMID:24843398
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Influence of the implant-abutment connection design and diameter on the screw joint stability.
Shin, Hyon-Mo; Huh, Jung-Bo; Yun, Mi-Jeong; Jeon, Young-Chan; Chang, Brian Myung; Jeong, Chang-Mo
2014-04-01
This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (α=0.05). THE POSTLOAD REMOVAL TORQUE VALUE WAS HIGH IN THE FOLLOWING ORDER WITH REGARD TO MAGNITUDE: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.
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Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship?
Lanza, Marcel B; Balshaw, Thomas G; Folland, Jonathan P
2017-08-01
What is the central question of the study? Do changes in neuromuscular activation contribute to the knee extensor angle-torque relationship? What is the main finding and its importance? Both agonist (quadriceps) and antagonist coactivation (hamstrings) differed with knee joint angle during maximal isometric knee extensions and thus both are likely to contribute to the angle-torque relationship. Specifically, two independent measurement techniques showed quadriceps activation to be lower at more extended positions. These effects might influence the capacity for neural changes in response to training and rehabilitation at different knee joint angles. The influence of joint angle on knee extensor neuromuscular activation is unclear, owing in part to the diversity of surface electromyography (sEMG) and/or interpolated twitch technique (ITT) methods used. The aim of the study was to compare neuromuscular activation, using rigorous contemporary sEMG and ITT procedures, during isometric maximal voluntary contractions (iMVCs) of the quadriceps femoris at different knee joint angles and examine whether activation contributes to the angle-torque relationship. Sixteen healthy active men completed two familiarization sessions and two experimental sessions of isometric knee extension and knee flexion contractions. The experimental sessions included the following at each of four joint angles (25, 50, 80 and 106 deg): iMVCs (with and without superimposed evoked doublets); submaximal contractions with superimposed doublets; and evoked twitch and doublet contractions whilst voluntarily passive, and knee flexion iMVC at the same knee joint positions. The absolute quadriceps femoris EMG was normalized to the peak-to-peak amplitude of an evoked maximal M-wave, and the doublet-voluntary torque relationship was used to calculate activation with the ITT. Agonist activation, assessed with both normalized EMG and the ITT, was reduced at the more extended compared with the more flexed
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Maeda, Rodrigo S; Cluff, Tyler; Gribble, Paul L; Pruszynski, J Andrew
2017-10-01
Moving the arm is complicated by mechanical interactions that arise between limb segments. Such intersegmental dynamics cause torques applied at one joint to produce movement at multiple joints, and in turn, the only way to create single joint movement is by applying torques at multiple joints. We investigated whether the nervous system accounts for intersegmental limb dynamics across the shoulder, elbow, and wrist joints during self-initiated planar reaching and when countering external mechanical perturbations. Our first experiment tested whether the timing and amplitude of shoulder muscle activity account for interaction torques produced during single-joint elbow movements from different elbow initial orientations and over a range of movement speeds. We found that shoulder muscle activity reliably preceded movement onset and elbow agonist activity, and was scaled to compensate for the magnitude of interaction torques arising because of forearm rotation. Our second experiment tested whether elbow muscles compensate for interaction torques introduced by single-joint wrist movements. We found that elbow muscle activity preceded movement onset and wrist agonist muscle activity, and thus the nervous system predicted interaction torques arising because of hand rotation. Our third and fourth experiments tested whether shoulder muscles compensate for interaction torques introduced by different hand orientations during self-initiated elbow movements and to counter mechanical perturbations that caused pure elbow motion. We found that the nervous system predicted the amplitude and direction of interaction torques, appropriately scaling the amplitude of shoulder muscle activity during self-initiated elbow movements and rapid feedback control. Taken together, our results demonstrate that the nervous system robustly accounts for intersegmental dynamics and that the process is similar across the proximal to distal musculature of the arm as well as between feedforward (i
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Design and Performance Analysis of a new Rotary Hydraulic Joint
Feng, Yong; Yang, Junhong; Shang, Jianzhong; Wang, Zhuo; Fang, Delei
2017-07-01
To improve the driving torque of the robots joint, a wobble plate hydraulic joint is proposed, and the structure and working principle are described. Then mathematical models of kinematics and dynamics was established. On the basis of this, dynamic simulation and characteristic analysis are carried out. Results show that the motion curve of the joint is continuous and the impact is small. Moreover the output torque of the joint characterized by simple structure and easy processing is large and can be rotated continuously.
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Electrostatic sensor modeling for torque measurements
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.
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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.
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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)
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Regularity in an environment produces an internal torque pattern for biped balance control.
Ito, Satoshi; Kawasaki, Haruhisa
2005-04-01
In this paper, we present a control method for achieving biped static balance under unknown periodic external forces whose periods are only known. In order to maintain static balance adaptively in an uncertain environment, it is essential to have information on the ground reaction forces. However, when the biped is exposed to a steady environment that provides an external force periodically, uncertain factors on the regularity with respect to a steady environment are gradually clarified using learning process, and finally a torque pattern for balancing motion is acquired. Consequently, static balance is maintained without feedback from ground reaction forces and achieved in a feedforward manner.
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Bevel gear driver and method having torque limit selection
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
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Model-Based Estimation of Ankle Joint Stiffness
Directory of Open Access Journals (Sweden)
Berno J. E. Misgeld
2017-03-01
Full Text Available We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is driven by electromyographic signals. The model incorporates a two-dimensional kinematic description in the sagittal plane for the calculation of muscle lever arms and torques. To reduce estimation errors due to model uncertainties, a filtering algorithm is necessary that employs segmental orientation sensor measurements. Because of the model’s inherent nonlinearities and nonsmooth dynamics, a square-root cubature Kalman filter was developed. The performance of the novel estimation approach was evaluated in silico and in an experimental procedure. The experimental study was conducted with body-worn sensors and a test-bench that was specifically designed to obtain reference angle and torque measurements for a single joint. Results show that the filter is able to reconstruct joint angle positions, velocities and torque, as well as, joint stiffness during experimental test bench movements.
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Model-Based Estimation of Ankle Joint Stiffness.
Misgeld, Berno J E; Zhang, Tony; Lüken, Markus J; Leonhardt, Steffen
2017-03-29
We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is driven by electromyographic signals. The model incorporates a two-dimensional kinematic description in the sagittal plane for the calculation of muscle lever arms and torques. To reduce estimation errors due to model uncertainties, a filtering algorithm is necessary that employs segmental orientation sensor measurements. Because of the model's inherent nonlinearities and nonsmooth dynamics, a square-root cubature Kalman filter was developed. The performance of the novel estimation approach was evaluated in silico and in an experimental procedure. The experimental study was conducted with body-worn sensors and a test-bench that was specifically designed to obtain reference angle and torque measurements for a single joint. Results show that the filter is able to reconstruct joint angle positions, velocities and torque, as well as, joint stiffness during experimental test bench movements.
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Model-Based Estimation of Ankle Joint Stiffness
Misgeld, Berno J. E.; Zhang, Tony; Lüken, Markus J.; Leonhardt, Steffen
2017-01-01
We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is driven by electromyographic signals. The model incorporates a two-dimensional kinematic description in the sagittal plane for the calculation of muscle lever arms and torques. To reduce estimation errors due to model uncertainties, a filtering algorithm is necessary that employs segmental orientation sensor measurements. Because of the model’s inherent nonlinearities and nonsmooth dynamics, a square-root cubature Kalman filter was developed. The performance of the novel estimation approach was evaluated in silico and in an experimental procedure. The experimental study was conducted with body-worn sensors and a test-bench that was specifically designed to obtain reference angle and torque measurements for a single joint. Results show that the filter is able to reconstruct joint angle positions, velocities and torque, as well as, joint stiffness during experimental test bench movements. PMID:28353683
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Subspace methods for identification of human ankle joint stiffness.
Zhao, Y; Westwick, D T; Kearney, R E
2011-11-01
Joint stiffness, the dynamic relationship between the angular position of a joint and the torque acting about it, describes the dynamic, mechanical behavior of a joint during posture and movement. Joint stiffness arises from both intrinsic and reflex mechanisms, but the torques due to these mechanisms cannot be measured separately experimentally, since they appear and change together. Therefore, the direct estimation of the intrinsic and reflex stiffnesses is difficult. In this paper, we present a new, two-step procedure to estimate the intrinsic and reflex components of ankle stiffness. In the first step, a discrete-time, subspace-based method is used to estimate a state-space model for overall stiffness from the measured overall torque and then predict the intrinsic and reflex torques. In the second step, continuous-time models for the intrinsic and reflex stiffnesses are estimated from the predicted intrinsic and reflex torques. Simulations and experimental results demonstrate that the algorithm estimates the intrinsic and reflex stiffnesses accurately. The new subspace-based algorithm has three advantages over previous algorithms: 1) It does not require iteration, and therefore, will always converge to an optimal solution; 2) it provides better estimates for data with high noise or short sample lengths; and 3) it provides much more accurate results for data acquired under the closed-loop conditions, that prevail when subjects interact with compliant loads.
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Directory of Open Access Journals (Sweden)
C Krás Borges
2007-12-01
literature are associated with tasks involving effort and repetitive movements of the arms and hands. Elbow position is known to affect the production of maximum forearm supination torque, and is a critical factor in designing appropriate therapeutic exercises. However, to our knowledge, there are no data on the effects of elbow position on tasks requiring control over submaximal torque levels. OBJECTIVE: This study investigated the effects of elbow position on the production of maximum isometric forearm supination torque, and on constant and continuous torque control at different submaximal torque levels. METHOD: Sixteen young adults (24.7 ± 2.2 years old were asked to perform two tasks: production of maximum lateral pinch torque (thumb and index finger and controlled lateral pinch constant torque. Both tasks were evaluated at four different elbow positions (free position, 0º, 45º and 90º of elbow flexion and three submaximal levels of lateral pinch torque production (20%, 40% and 60%. Maximal torque, variability, irregularity and accuracy of the motor response were used as dependent variables. RESULTS: Greater torque values were found when the elbow joint was not restricted. The torque control tasks were not affected by the elbow position. However, greater variability and irregularity and lower accuracy in torque response were recorded with progressively increased submaximal torque levels. CONCLUSION: The results suggest that elbow position is not a determining factor for rehabilitation exercises that include torque control, in relation to forearm supination.
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Review of Bolt Preload and Torque for Assembling Threaded Fasteners in Nuclear Power Plant
International Nuclear Information System (INIS)
Lee, Yong-Sung; Lee, Jae-Gon; Kang, Yong-Chul; Shin, Ki-Jong
2007-01-01
There are numerous threaded fasteners such as bolts, studs, nuts, cap screws and anchor bolts used in nuclear power plants(NPPs). The major applications of threaded fasteners are reactor coolant pressure boundary components, their internals and supports. With the increase of commercial operation period of NPPs, the incidents caused by degradation of threaded fasteners have been occurred. A large number of reported incidents are involved in the pressure boundary and major component supports. The degradation and failure of threaded fasteners is affected by material, preload and torque value at assembly, bolting practice, etc. It is very important to select appropriate bolt preload and decide assembly torque value because torque control using a torque wrench is the most common method in a power plant to assemble a bolted flange connection. Many researches have been studied to define the proper bolt preload and desired torque value with regard to the integrity of bolted connections including pressure boundary joints by EPRI and other plant industry. But in domestic NPPs, considerably few works are done on the bolted joint assembly in spite of increasing events related with threaded faster. Therefore we investigated degradation or failure of the threaded fasteners used in NPPs, also examined the codes, standards and technical trends concerning bolt preload and assembly torque in NPPs. It is the purpose of this study to provide proper technical information for assuring integrity of the threaded fasteners
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Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio
2013-01-01
An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input.
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Hip joint kinetics in the table tennis topspin forehand: relationship to racket velocity.
Iino, Yoichi
2018-04-01
The purpose of this study was to determine hip joint kinetics during a table tennis topspin forehand, and to investigate the relationship between the relevant kinematic and kinetic variables and the racket horizontal and vertical velocities at ball impact. Eighteen male advanced table tennis players hit cross-court topspin forehands against backspin balls. The hip joint torque and force components around the pelvis coordinate system were determined using inverse dynamics. Furthermore, the work done on the pelvis by these components was also determined. The peak pelvis axial rotation velocity and the work done by the playing side hip pelvis axial rotation torque were positively related to the racket horizontal velocity at impact. The sum of the work done on the pelvis by the backward tilt torques and the upward joint forces was positively related to the racket vertical velocity at impact. The results suggest that the playing side hip pelvis axial rotation torque exertion is important for acquiring a high racket horizontal velocity at impact. The pelvis backward tilt torques and upward joint forces at both hip joints collectively contribute to the generation of the racket vertical velocity, and the mechanism for acquiring the vertical velocity may vary among players.
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A Method for and Issues Associated with the Determination of Space Suit Joint Requirements
Matty, Jennifer E.; Aitchison, Lindsay
2009-01-01
In the design of a new space suit it is necessary to have requirements that define what mobility space suit joints should be capable of achieving in both a system and at the component level. NASA elected to divide mobility into its constituent parts-range of motion (ROM) and torque- in an effort to develop clean design requirements that limit subject performance bias and are easily verified. Unfortunately, the measurement of mobility can be difficult to obtain. Current technologies, such as the Vicon motion capture system, allow for the relatively easy benchmarking of range of motion (ROM) for a wide array of space suit systems. The ROM evaluations require subjects in the suit to accurately evaluate the ranges humans can achieve in the suit. However, when it comes to torque, there are significant challenges for both benchmarking current performance and writing requirements for future suits. This is reflected in the fact that torque definitions have been applied to very few types of space suits and with limited success in defining all the joints accurately. This paper discussed the advantages and disadvantages to historical joint torque evaluation methods, describes more recent efforts directed at benchmarking joint torques of prototype space suits, and provides an outline for how NASA intends to address joint torque in design requirements for the Constellation Space Suit System (CSSS).
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Patellofemoral joint stress during running with alterations in foot strike pattern.
Vannatta, Charles Nathan; Kernozek, Thomas W
2015-05-01
This study aimed to quantify differences in patellofemoral joint stress that may occur when healthy runners alter their foot strike pattern from their habitual rearfoot strike to a forefoot strike to gain insight on the potential etiology and treatment methods of patellofemoral pain. Sixteen healthy female runners completed 20 running trials in a controlled laboratory setting under rearfoot strike and forefoot strike conditions. Kinetic and kinematic data were used to drive a static optimization technique to estimate individual muscle forces to input into a model of the patellofemoral joint to estimate joint stress during running. Peak patellofemoral joint stress and the stress-time integral over stance phase decreased by 27% and 12%, respectively, in the forefoot strike condition (P forefoot strike condition (P forefoot strike (P forefoot strike condition (P strike pattern to a forefoot strike results in consistent reductions in patellofemoral joint stress independent of changes in step length. Thus, implementation of forefoot strike training programs may be warranted in the treatment of runners with patellofemoral pain. However, it is suggested that the transition to a forefoot strike pattern should be completed in a graduated manner.
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Influence of step length and landing pattern on patellofemoral joint kinetics during running.
Willson, J D; Ratcliff, O M; Meardon, S A; Willy, R W
2015-12-01
Elevated patellofemoral joint kinetics during running may contribute to patellofemoral joint symptoms. The purpose of this study was to test for independent effects of foot strike pattern and step length on patellofemoral joint kinetics while running. Effects were tested relative to individual steps and also taking into account the number of steps required to run a kilometer with each step length. Patellofemoral joint reaction force and stress were estimated in 20 participants running at their preferred speed. Participants ran using a forefoot strike and rearfoot strike pattern during three different step length conditions: preferred step length, long (+10%) step length, and short (-10%) step length. Patellofemoral kinetics was estimated using a biomechanical model of the patellofemoral joint that accounted for cocontraction of the knee flexors and extensors. We observed independent effects of foot strike pattern and step length. Patellofemoral joint kinetics per step was 10-13% less during forefoot strike conditions and 15-20% less with a shortened step length. Patellofemoral joint kinetics per kilometer decreased 12-13% using a forefoot strike pattern and 9-12% with a shortened step length. To the extent that patellofemoral joint kinetics contribute to symptoms among runners, these running modifications may be advisable for runners with patellofemoral pain. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Out-of-plane spin-transfer torques: First-principles study
Czech Academy of Sciences Publication Activity Database
Carva, K.; Turek, Ilja
2010-01-01
Roč. 322, 9-12 (2010), s. 1085-1087 ISSN 0304-8853. [Joint European Magnetic Symposia /4./. Dublin, 14.09.2008-19.09.2008] Institutional research plan: CEZ:AV0Z20410507 Keywords : spin-transfer torque * spin-mixing conductance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.689, year: 2010
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ESTIMATION OF GRASPING TORQUE USING ROBUST REACTION TORQUE OBSERVER FOR ROBOTIC FORCEPS
塚本, 祐介
2015-01-01
Abstract— In this paper, the estimation of the grasping torque of robotic forceps without the use of a force/torque sensor is discussed. To estimate the grasping torque when the robotic forceps driven by a rotary motor with a reduction gear grasps an object, a novel robust reaction torque observer is proposed. In the case where a conventional reaction force/torque observer is applied, the estimated torque includes not only the grasping torque, namely the reaction torque, but also t...
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Meng, Feng; Zhang, Zhimin; Lin, Jing
The paper describes the reference torque standard machine with high accuracy and multifunction, developed by our institute, and introduces the structure and working principle of this machine. It has three main functions. The first function is the hydraulic torque wrench calibration function. The second function is torque multiply calibration function. The third function is reference torque standard machine function. We can calibrate the torque multipliers, hydraulic wrenches and transducers by this machine. A comparison experiment has been done between this machine and a deadweight torque standard machine. The consistency between the 30 kNm reference torque machine and the 2000 Nm dead-weight torque standard machine under the claimed uncertainties was verified.
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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.
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Nieuwenhuys, Angela; Papageorgiou, Eirini; Desloovere, Kaat; Molenaers, Guy; De Laet, Tinne
2017-01-01
Experts recently identified 49 joint motion patterns in children with cerebral palsy during a Delphi consensus study. Pattern definitions were therefore the result of subjective expert opinion. The present study aims to provide objective, quantitative data supporting the identification of these consensus-based patterns. To do so, statistical parametric mapping was used to compare the mean kinematic waveforms of 154 trials of typically developing children (n = 56) to the mean kinematic waveforms of 1719 trials of children with cerebral palsy (n = 356), which were classified following the classification rules of the Delphi study. Three hypotheses stated that: (a) joint motion patterns with 'no or minor gait deviations' (n = 11 patterns) do not differ significantly from the gait pattern of typically developing children; (b) all other pathological joint motion patterns (n = 38 patterns) differ from typically developing gait and the locations of difference within the gait cycle, highlighted by statistical parametric mapping, concur with the consensus-based classification rules. (c) all joint motion patterns at the level of each joint (n = 49 patterns) differ from each other during at least one phase of the gait cycle. Results showed that: (a) ten patterns with 'no or minor gait deviations' differed somewhat unexpectedly from typically developing gait, but these differences were generally small (≤3°); (b) all other joint motion patterns (n = 38) differed from typically developing gait and the significant locations within the gait cycle that were indicated by the statistical analyses, coincided well with the classification rules; (c) joint motion patterns at the level of each joint significantly differed from each other, apart from two sagittal plane pelvic patterns. In addition to these results, for several joints, statistical analyses indicated other significant areas during the gait cycle that were not included in the pattern definitions of the consensus study
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Magnetic Field and Torque Output of Packaged Hydraulic Torque Motor
Directory of Open Access Journals (Sweden)
Liang Yan
2018-01-01
Full Text Available Hydraulic torque motors are one key component in electro-hydraulic servo valves that convert the electrical signal into mechanical motions. The systematic characteristics analysis of the hydraulic torque motor has not been found in the previous research, including the distribution of the electromagnetic field and torque output, and particularly the relationship between them. In addition, conventional studies of hydraulic torque motors generally assume an evenly distributed magnetic flux field and ignore the influence of special mechanical geometry in the air gaps, which may compromise the accuracy of analyzing the result and the high-precision motion control performance. Therefore, the objective of this study is to conduct a detailed analysis of the distribution of the magnetic field and torque output; the influence of limiting holes in the air gaps is considered to improve the accuracy of both numerical computation and analytical modeling. The structure and working principle of the torque motor are presented first. The magnetic field distribution in the air gaps and the magnetic saturation in the iron blocks are analyzed by using a numerical approach. Subsequently, the torque generation with respect to the current input and assembly errors is analyzed in detail. This shows that the influence of limiting holes on the magnetic field is consistent with that on torque generation. Following this, a novel modified equivalent magnetic circuit is proposed to formulate the torque output of the hydraulic torque motor analytically. The comparison among the modified equivalent magnetic circuit, the conventional modeling approach and the numerical computation is conducted, and it is found that the proposed method helps to improve the modeling accuracy by taking into account the effect of special geometry inside the air gaps.
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Independently controlled wing stroke patterns in the fruit fly Drosophila melanogaster.
Directory of Open Access Journals (Sweden)
Soma Chakraborty
Full Text Available Flies achieve supreme flight maneuverability through a small set of miniscule steering muscles attached to the wing base. The fast flight maneuvers arise from precisely timed activation of the steering muscles and the resulting subtle modulation of the wing stroke. In addition, slower modulation of wing kinematics arises from changes in the activity of indirect flight muscles in the thorax. We investigated if these modulations can be described as a superposition of a limited number of elementary deformations of the wing stroke that are under independent physiological control. Using a high-speed computer vision system, we recorded the wing motion of tethered flying fruit flies for up to 12,000 consecutive wing strokes at a sampling rate of 6250 Hz. We then decomposed the joint motion pattern of both wings into components that had the minimal mutual information (a measure of statistical dependence. In 100 flight segments measured from 10 individual flies, we identified 7 distinct types of frequently occurring least-dependent components, each defining a kinematic pattern (a specific deformation of the wing stroke and the sequence of its activation from cycle to cycle. Two of these stroke deformations can be associated with the control of yaw torque and total flight force, respectively. A third deformation involves a change in the downstroke-to-upstroke duration ratio, which is expected to alter the pitch torque. A fourth kinematic pattern consists in the alteration of stroke amplitude with a period of 2 wingbeat cycles, extending for dozens of cycles. Our analysis indicates that these four elementary kinematic patterns can be activated mutually independently, and occur both in isolation and in linear superposition. The results strengthen the available evidence for independent control of yaw torque, pitch torque, and total flight force. Our computational method facilitates systematic identification of novel patterns in large kinematic datasets.
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Independently controlled wing stroke patterns in the fruit fly Drosophila melanogaster.
Chakraborty, Soma; Bartussek, Jan; Fry, Steven N; Zapotocky, Martin
2015-01-01
Flies achieve supreme flight maneuverability through a small set of miniscule steering muscles attached to the wing base. The fast flight maneuvers arise from precisely timed activation of the steering muscles and the resulting subtle modulation of the wing stroke. In addition, slower modulation of wing kinematics arises from changes in the activity of indirect flight muscles in the thorax. We investigated if these modulations can be described as a superposition of a limited number of elementary deformations of the wing stroke that are under independent physiological control. Using a high-speed computer vision system, we recorded the wing motion of tethered flying fruit flies for up to 12,000 consecutive wing strokes at a sampling rate of 6250 Hz. We then decomposed the joint motion pattern of both wings into components that had the minimal mutual information (a measure of statistical dependence). In 100 flight segments measured from 10 individual flies, we identified 7 distinct types of frequently occurring least-dependent components, each defining a kinematic pattern (a specific deformation of the wing stroke and the sequence of its activation from cycle to cycle). Two of these stroke deformations can be associated with the control of yaw torque and total flight force, respectively. A third deformation involves a change in the downstroke-to-upstroke duration ratio, which is expected to alter the pitch torque. A fourth kinematic pattern consists in the alteration of stroke amplitude with a period of 2 wingbeat cycles, extending for dozens of cycles. Our analysis indicates that these four elementary kinematic patterns can be activated mutually independently, and occur both in isolation and in linear superposition. The results strengthen the available evidence for independent control of yaw torque, pitch torque, and total flight force. Our computational method facilitates systematic identification of novel patterns in large kinematic datasets.
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A magneto-rheological fluid-based torque sensor for smart torque wrench application
Ahmadkhanlou, Farzad; Washington, Gregory N.
2013-04-01
In this paper, the authors have developed a new application where MR fluid is being used as a sensor. An MR-fluid based torque wrench has been developed with a rotary MR fluid-based damper. The desired set torque ranges from 1 to 6 N.m. Having continuously controllable yield strength, the MR fluid-based torque wrench presents a great advantage over the regular available torque wrenches in the market. This design is capable of providing continuous set toque from the lower limit to the upper limit while regular torque wrenches provide discrete set torques only at some limited points. This feature will be especially important in high fidelity systems where tightening torque is very critical and the tolerances are low.
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Spin-orbit torque opposing the Oersted torque in ultrathin Co/Pt bilayers
Energy Technology Data Exchange (ETDEWEB)
Skinner, T. D., E-mail: tds32@cam.ac.uk; Irvine, A. C.; Heiss, D.; Kurebayashi, H.; Ferguson, A. J., E-mail: ajf1006@cam.ac.uk [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Wang, M.; Hindmarch, A. T.; Rushforth, A. W. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
2014-02-10
Current-induced torques in ultrathin Co/Pt bilayers were investigated using an electrically driven ferromagnetic resonance technique. The angle dependence of the resonances, detected by a rectification effect as a voltage, was analysed to determine the symmetries and relative magnitudes of the spin-orbit torques. Both anti-damping (Slonczewski) and field-like torques were observed. As the ferromagnet thickness was reduced from 3 to 1 nm, the sign of the sum of the field-like torque and Oersted torque reversed. This observation is consistent with the emergence of a Rashba spin orbit torque in ultra-thin bilayers.
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Immediate effects of whole body vibration on patellar tendon properties and knee extension torque.
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.
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Estimating net joint torques from kinesiological data using optimal linear system theory.
Runge, C F; Zajac, F E; Allum, J H; Risher, D W; Bryson, A E; Honegger, F
1995-12-01
Net joint torques (NJT) are frequently computed to provide insights into the motor control of dynamic biomechanical systems. An inverse dynamics approach is almost always used, whereby the NJT are computed from 1) kinematic measurements (e.g., position of the segments), 2) kinetic measurements (e.g., ground reaction forces) that are, in effect, constraints defining unmeasured kinematic quantities based on a dynamic segmental model, and 3) numerical differentiation of the measured kinematics to estimate velocities and accelerations that are, in effect, additional constraints. Due to errors in the measurements, the segmental model, and the differentiation process, estimated NJT rarely produce the observed movement in a forward simulation when the dynamics of the segmental system are inherently unstable (e.g., human walking). Forward dynamic simulations are, however, essential to studies of muscle coordination. We have developed an alternative approach, using the linear quadratic follower (LQF) algorithm, which computes the NJT such that a stable simulation of the observed movement is produced and the measurements are replicated as well as possible. The LQF algorithm does not employ constraints depending on explicit differentiation of the kinematic data, but rather employs those depending on specification of a cost function, based on quantitative assumptions about data confidence. We illustrate the usefulness of the LQF approach by using it to estimate NJT exerted by standing humans perturbed by support-surface movements. We show that unless the number of kinematic and force variables recorded is sufficiently high, the confidence that can be placed in the estimates of the NJT, obtained by any method (e.g., LQF, or the inverse dynamics approach), may be unsatisfactorily low.
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Self-oscillation in spin torque oscillator stabilized by field-like torque
International Nuclear Information System (INIS)
Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi
2014-01-01
The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation
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Muscle Torque and its Relation to Technique, Tactics, Sports Level and Age Group in Judo Contestants
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
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Lech, Grzegorz; Chwała, Wiesław; Ambroży, Tadeusz; Sterkowicz, Stanisław
2015-03-29
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).
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Robust Control of a Cable-Driven Soft Exoskeleton Joint for Intrinsic Human-Robot Interaction.
Jarrett, C; McDaid, A J
2017-07-01
A novel, cable-driven soft joint is presented for use in robotic rehabilitation exoskeletons to provide intrinsic, comfortable human-robot interaction. The torque-displacement characteristics of the soft elastomeric core contained within the joint are modeled. This knowledge is used in conjunction with a dynamic system model to derive a sliding mode controller (SMC) to implement low-level torque control of the joint. The SMC controller is experimentally compared with a baseline feedback-linearised proportional-derivative controller across a range of conditions and shown to be robust to un-modeled disturbances. The torque controller is then tested with six healthy subjects while they perform a selection of activities of daily living, which has validated its range of performance. Finally, a case study with a participant with spastic cerebral palsy is presented to illustrate the potential of both the joint and controller to be used in a physiotherapy setting to assist clinical populations.
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Accuracy of dental torque wrenches.
Wood, James S; Marlow, Nicole M; Cayouette, Monica J
2015-01-01
The aim of this in vitro study was to compare the actual torque of 2 manual wrench systems to their stated (target) torque. New spring- (Nobel Biocare USA, LLC) and friction-style (Zimmer Dental, Inc.) manual dental torque wrenches, as well as spring torque wrenches that had undergone sterilization and clinical use, were tested. A calibrated torque gauge was used to compare actual torque to target torque values of 15 and 35 N/cm. Data were statistically analyzed via mixed-effects regression model with Bonferroni correction. At a target torque of 15 N/cm, the mean torque of new spring wrenches (13.97 N/cm; SE, 0.07 N/cm) was significantly different from that of used spring wrenches (14.94 N/cm; SE, 0.06 N/cm; P torques of new spring and new friction wrenches (14.10 N/cm; SE, 0.07 N/cm; P = 0.21) were not significantly different. For torque measurements calibrated at 35 N/cm, the mean torque of new spring wrenches (35.29 N/cm; SE, 0.10 N/cm) was significantly different (P torque could impact the clinical success of screw-retained dental implants. It is recommended that torque wrenches be checked regularly to ensure that they are performing to target values.
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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.
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Rotational and peak torque stiffness of rugby shoes.
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.
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Optimal tightening process of bolted joints
Directory of Open Access Journals (Sweden)
Monville Jean-Michel
2016-01-01
Full Text Available Threaded fasteners were developed long time (let’s remember that Archimedes – 287-212 BC – invented the water screw. Nowadays, bolted joints are used in almost all sectors of the industry. But in spite of having been an important machine part for centuries, problems may be encountered with them. They are so common that they are taken for granted and too often, not analyzed as deeply as it should be. The wrong tightening is one of the most frequent causes of ductile rupture and by far the most frequent cause of fatigue failure. The tightening operation is never easy. It is necessary to pay particular attention to the choice of the tightening tool, the process and the control method. The tightening operation may itself cause damage on parts. The tightening load must not be too low, or excessive or not equally distributed among the bolts. These three defects can even be made on the same bolted joint! This impacts badly the performance of the assembly and leads to a shorter lifespan. If insufficient precautions are taken, the real tightening preload on all the bolts will not fit well with the requirements and would be badly distributed. Consequently, the practical conditions are quite different from the hypothesizes which are taken for the initial calculations (analytics or FEM at the design stage. Thus, the results of the calculations of bolted joints cannot be considered as accurate and reliable. Practically, there are several means to tighten a bolt. The two ways most frequently used are torque wrench and hydraulic bolt tensioner. Torque wrench involves exerting a torque to the bolt head or the nut. Hydraulic bolt tensioner applies a traction load directly on the bolt. It is well known that bolt tensioners give better accuracy and homogeneity in the final tightening load than the torque method, but the tension load applied with the tensioner must be higher than the final remaining tightening load. So, the paper focusses on the hydraulic
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Energy Technology Data Exchange (ETDEWEB)
Kurosawa, M; Fujikawa, T; Yoshida, K; Kobayahi, M [Nissan Motor Co. Ltd., Tokyo (Japan)
1997-10-01
Nissan has successfully developed a new belt CVT (Continuously Variable Transmission) with torque converter and has installed it 2L-class vehicle for the first time in the world. This paper describes about the technology of high torque transmission, the need of torque converter, the importance of electronic control and the introduce of driving mode. As the result the CVT has improved driving performance and fuel economy for current CVT and 4 speed automatic transmission. 13 figs., 2 tabs.
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Actuation of a robotic fish caudal fin for low reaction torque
Yun, Dongwon; Kim, Kyung-Soo; Kim, Soohyun; Kyung, Jinho; Lee, Sunghee
2011-07-01
In this paper, a novel caudal fin for actuating a robotic fish is presented. The proposed caudal fin waves in a vertical direction with a specific spatial shape, which is determined by a so-called shape factor. For a specific shape factor, a traveling wave with a vertical phase difference is formed on a caudal fin during fin motion. It will be shown by the analysis that the maximum reaction torque at the joint of a caudal fin varies depending on the shape factors. Compared with a conventional plate type caudal fin, the proposed fin with a shape factor of 2π can eliminate the reaction torque perfectly, while keeping the propulsion force unchanged. The benefits of the proposed fin will be demonstrated by experiments.
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Intrinsic constraint of unlinked total elbow replacements--the ulnotrochlear joint.
Kamineni, S; O'Driscoll, S W; Urban, M; Garg, A; Berglund, L J; Morrey, B F; An, K N
2005-09-01
Many unlinked total elbow replacement designs with radically differing articular geometries exist, suggesting that there is no consensus regarding an optimal design. A feature inherent to the articular design is the intrinsic constraint afforded to the joint by the implant. Our aim was to compare the intrinsic constraints of unlinked implants with that of the normal ulnotrochlear joint. We tested twelve cadaveric ulnotrochlear joints with a custom-made multiple-axis materials testing machine. With compressive loads ranging from 10 to 100 N, the joints were moved in either valgus or varus directions at 90 degrees of flexion. The ulnotrochlear components from a single example of five medium-sized unlinked elbow replacements (Ewald, Kudo, Pritchard ERS, Sorbie-Questor, and Souter-Strathclyde) were also tested. The recorded measurements included the torques and forces, angular displacement, and axial displacement of the humerus relative to the ulna. In general, the peak torque and the constraint ratio significantly increased with increasing compressive load for the implants as well as for the normal elbow. In valgus displacement, the Souter-Strathclyde implant had the highest and the Sorbie-Questor had the smallest peak torque and the Souter-Strathclyde had the highest and the Ewald had the smallest constraint ratio. In varus displacement, the Kudo had the highest and the Ewald had the smallest peak torque and constraint ratio. The constraint ratio is a characteristic that is useful for describing elbow joint behavior and for comparing the behavior of implants with that of the human elbow. Of the unlinked implants tested, the Souter-Strathclyde and Kudo prostheses most closely approximated the behavior of the human elbow joint. Implants that resemble the human elbow in appearance do not replicate normal behavior consistently, whereas other implants that do not resemble the human elbow closely do not deviate markedly from human behavior. Thus, much basic information
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Using torque switch settings and spring pack characteristics to determine actuator output torques
International Nuclear Information System (INIS)
Black, B.R.
1992-01-01
Actuator output torque of motor operated valves is often a performance parameter of interest. It is not always possible to directly measure this torque. Torque spring pack deflection directly reflects actuator output torque and can be directly measured on most actuators. The torque spring pack may be removed from the actuator and tested to determine its unique force-deflection relationship. Or, a representative force-deflection relationship for the particular spring pack model may be available. With either relationship, measurements of torque spring pack deflection may then be correlated to corresponding forces. If the effective length of the moment arm within the actuator is known, actuator output torque can then be determined. The output torque is simply the product of the effective moment arm length and the spring pack force. This paper presents the reliability of this technique as indicated by testing. TU Electric is evaluating this technique for potential use in the future. Results presented in this paper should be considered preliminary. Applicability of these results may be limited to actuators and their components in a condition similar to those for which test data have been examined
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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.
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Efficient micromagnetic modelling of spin-transfer torque and spin-orbit torque
Abert, Claas; Bruckner, Florian; Vogler, Christoph; Suess, Dieter
2018-05-01
While the spin-diffusion model is considered one of the most complete and accurate tools for the description of spin transport and spin torque, its solution in the context of dynamical micromagnetic simulations is numerically expensive. We propose a procedure to retrieve the free parameters of a simple macro-spin like spin-torque model through the spin-diffusion model. In case of spin-transfer torque the simplified model complies with the model of Slonczewski. A similar model can be established for the description of spin-orbit torque. In both cases the spin-diffusion model enables the retrieval of free model parameters from the geometry and the material parameters of the system. Since these parameters usually have to be determined phenomenologically through experiments, the proposed method combines the strength of the diffusion model to resolve material parameters and geometry with the high performance of simple torque models.
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Optical Torque Wrench: Angular Trapping, Rotation, and Torque Detection of Quartz Microparticles
La Porta, Arthur; Wang, Michelle D.
2004-05-01
We describe an apparatus that can measure the instantaneous angular displacement and torque applied to a quartz particle which is angularly trapped. Torque is measured by detecting the change in angular momentum of the transmitted trap beam. The rotational Brownian motion of the trapped particle and its power spectral density are used to determine the angular trap stiffness. The apparatus features a feedback control that clamps torque or other rotational quantities. The torque sensitivity demonstrated is ideal for the study of known biological molecular motors.
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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
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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.
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Game programmer's guide to Torque under the hood of the Torque game engine
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
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Rosenberg, John H; Rai, Vikrant; Dilisio, Matthew F; Sekundiak, Todd D; Agrawal, Devendra K
2017-12-01
Osteoarthritis (OA) is a degenerative disease characterized by the destruction of cartilage. The greatest risk factors for the development of OA include age and obesity. Recent studies suggest the role of inflammation in the pathogenesis of OA. The two most common locations for OA to occur are in the knee and hip joints. The knee joint experiences more mechanical stress, cartilage degeneration, and inflammation than the hip joint. This could contribute to the increased incidence of OA in the knee joint. Damage-associated molecular patterns (DAMPs), including high-mobility group box-1, receptor for advanced glycation end products, and alarmins (S100A8 and S100A9), are released in the joint in response to stress-mediated chondrocyte and cartilage damage. This facilitates increased cartilage degradation and inflammation in the joint. Studies have documented the role of DAMPs in the pathogenesis of OA; however, the comparison of DAMPs and its influence on OA has not been discussed. In this study, we compared the DAMPs between OA knee and hip joints and found a significant difference in the levels of DAMPs expressed in the knee joint compared to the hip joint. The increased levels of DAMPs suggest a difference in the underlying pathogenesis of OA in the knee and the hip and highlights DAMPs as potential therapeutic targets for OA in the future.
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Fgeppert, E.
1984-09-01
Mechanical means for sensing turning torque generated by the load forces in a rotary drive system is described. The sensing means is designed to operate with minimal effect on normal operation of the drive system. The invention can be employed in various drive systems, e.g., automotive engine-transmission power plants, electric motor-operated tools, and metal cutting machines. In such drive systems, the torque-sensing feature may be useful for actuation of various control devices, such as electric switches, mechanical clutches, brake actuators, fluid control valves, or audible alarms. The torque-sensing function can be used for safety overload relief, motor de-energization, engine fuel control transmission clutch actuation, remote alarm signal, tool breakage signal, etc.
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Divergent dislocation of the ring and little finger carpometacarpal joints--a rare injury pattern.
LENUS (Irish Health Repository)
Dillon, John
2012-02-03
Hand injuries due to longitudinal forces in the line of the metacarpals demonstrate unusual dislocation patterns. We describe a case of volar intra-articular fracture dislocation of the ring finger carpometacarpal joint in association with a pure dorsal dislocation of the little finger carpometacarpal joint. Open reduction supplemented with Kirschner wire fixation restored normal carpometacarpal joint anatomical relations and achieved an excellent clinical result.
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Hu, X Q; Wood, R J K; Taylor, A; Tuke, M A
2011-11-01
Clearance is one of the most influential parameters on the tribological performance of metal-on-metal (MOM) hip joints and its selection is a subject of considerable debate. The objective of this paper is to study the lubrication behaviour of different clearances for MOM hip joints within the range of human physiological and pathological fluid viscosities. The frictional torques developed by MOM hip joints with a 50 mm diameter were measured for both virgin surfaces and during a wear simulator test. Joints were manufactured with three different diametral clearances: 20, 100, and 200 microm. The fluid used for the friction measurements which contained different ratios of 25 percent newborn calf serum and carboxymethyl cellulose (CMC) with the obtained viscosities values ranging from 0.001 to 0.71 Pa s. The obtained results indicate that the frictional torque for the 20 microm clearance joint remains high over the whole range of the viscosity values. The frictional torque of the 100 microm clearance joint was low for the very low viscosity (0.001 Pa s) lubricant, but increased with increasing viscosity value. The frictional torque of the 200 microm clearance joint was high at very low viscosity levels, however, it reduced with increasing viscosity. It is concluded that a smaller clearance level can enhance the formation of an elastohydrodynamic lubrication (EHL) film, but this is at the cost of preventing fluid recovery between the bearing surfaces during the unloaded phase of walking. Larger clearance bearings allow a better recovery of lubricant during the unloaded phase, which is necessary for higher viscosity lubricants. The selection of the clearance value should therefore consider both the formation of the EHL film and the fluid recovery as a function of the physiological viscosity in order to get an optimal tribological performance for MOM hip joints. The application of either 25 per cent bovine serum or water in existing in vitro tribological study should
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Whole-body patterns of the range of joint motion in young adults: masculine type and feminine type.
Moromizato, Keiichi; Kimura, Ryosuke; Fukase, Hitoshi; Yamaguchi, Kyoko; Ishida, Hajime
2016-10-01
Understanding the whole-body patterns of joint flexibility and their related biological and physical factors contributes not only to clinical assessments but also to the fields of human factors and ergonomics. In this study, ranges of motion (ROMs) at limb and trunk joints of young adults were analysed to understand covariation patterns of different joint motions and to identify factors associated with the variation in ROM. Seventy-eight healthy volunteers (42 males and 36 females) living on Okinawa Island, Japan, were recruited. Passive ROM was measured at multiple joints through the whole body (31 measurements) including the left and right side limbs and trunk. Comparisons between males and females, dominant and non-dominant sides, and antagonistic motions indicated that body structures influence ROMs. In principal component analysis (PCA) on the ROM data, the first principal component (PC1) represented the sex difference and a similar covariation pattern appeared in the analysis within each sex. Multiple regression analysis showed that this component was associated with sex, age, body fat %, iliospinale height, and leg extension strength. The present study identified that there is a spectrum of "masculine" and "feminine" types in the whole-body patterns of joint flexibility. This study also suggested that body proportion and composition, muscle mass and strength, and possibly skeletal structures partly explain such patterns. These results would be important to understand individual variation in susceptibility to joint injuries and diseases and in one's suitable and effective postures and motions.
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Momentum confinement at low torque
Energy Technology Data Exchange (ETDEWEB)
Solomon, W M [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Burrell, K H [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); De Grassie, J S [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Budny, R [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Groebner, R J [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Kinsey, J E [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Kramer, G J [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Luce, T C [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Makowski, M A [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Mikkelsen, D [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Nazikian, R [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Petty, C C [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Politzer, P A [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Scott, S D [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Zeeland, M A Van [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Zarnstorff, M C [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States)
2007-12-15
Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized beta {beta}{sub N}, by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q{sub min} show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. GLF23 modeling suggests that the role of E x B shearing is quite different between the two plasmas, which may help to explain the different dependence of the momentum confinement on torque.
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Low mass planet migration in magnetically torqued dead zones - I. Static migration torque
McNally, Colin P.; Nelson, Richard P.; Paardekooper, Sijme-Jan; Gressel, Oliver; Lyra, Wladimir
2017-12-01
Motivated by models suggesting that the inner planet forming regions of protoplanetary discs are predominantly lacking in viscosity-inducing turbulence, and are possibly threaded by Hall-effect generated large-scale horizontal magnetic fields, we examine the dynamics of the corotation region of a low-mass planet in such an environment. The corotation torque in an inviscid, isothermal, dead zone ought to saturate, with the libration region becoming both symmetrical and of a uniform vortensity, leading to fast inward migration driven by the Lindblad torques alone. However, in such a low viscosity situation, the material on librating streamlines essentially preserves its vortensity. If there is relative radial motion between the disc gas and the planet, the librating streamlines will no longer be symmetrical. Hence, if the gas is torqued by a large-scale magnetic field so that it undergoes a net inflow or outflow past the planet, driving evolution of the vortensity and inducing asymmetry of the corotation region, the corotation torque can grow, leading to a positive torque. In this paper, we treat this effect by applying a symmetry argument to the previously studied case of a migrating planet in an inviscid disc. Our results show that the corotation torque due to a laminar Hall-induced magnetic field in a dead zone behaves quite differently from that studied previously for a viscous disc. Furthermore, the magnetic field induced corotation torque and the dynamical corotation torque in a low viscosity disc can be regarded as one unified effect.
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Health monitoring of 90° bolted joints using fuzzy pattern recognition of ultrasonic signals
International Nuclear Information System (INIS)
Jalalpour, M; El-Osery, A I; Austin, E M; Reda Taha, M M
2014-01-01
Bolted joints are important parts for aerospace structures. However, there is a significant risk associated with assembling bolted joints due to potential human error during the assembly process. Such errors are expensive to find and correct if exposed during environmental testing, yet checking the integrity of individual fasteners after assembly would be a time consuming task. Recent advances in structural health monitoring (SHM) can provide techniques to not only automate this process but also make it reliable. This integrity monitoring requires damage features to be related to physical conditions representing the structural integrity of bolted joints. In this paper an SHM technique using ultrasonic signals and fuzzy pattern recognition to monitor the integrity of 90° bolted joints in aerospace structures is described. The proposed technique is based on normalized fast Fourier transform (NFFT) of transmitted signals and fuzzy pattern recognition. Moreover, experimental observations of a case study on an aluminum 90° bolted joint are presented. We demonstrate the ability of the proposed method to efficiently monitor and indicate bolted joint integrity. (paper)
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International Nuclear Information System (INIS)
Nishino, Atsuhiro; Ueda, Kazunaga; Fujii, Kenichi
2017-01-01
To allow the application of torque standards in various industries, we have been developing torque standard machines based on a lever deadweight system, i.e. a torque generation method using gravity. However, this method is not suitable for expanding the low end of the torque range, because of the limitations to the sizes of the weights and moment arms. In this study, the working principle of the torque generation method using an electromagnetic force was investigated by referring to watt balance experiments used for the redefinition of the kilogram. Applying this principle to a rotating coordinate system, an electromagnetic force type torque standard machine was designed and prototyped. It was experimentally demonstrated that SI-traceable torque could be generated by converting electrical power to mechanical power. Thus, for the first time, SI-traceable torque was successfully realized using a method other than that based on the force of gravity. (paper)
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Experiments of steady state head and torque of centrifugal pumps in two-phase flow
International Nuclear Information System (INIS)
Minato, Akihiko; Tominaga, Kenji.
1988-01-01
Circulation pump behavior has large effect on coolant discharge flow rate in case of reactor pipe break. Experiment of two-phase pump performance was conducted as a joint study of Japanese BWR user utilities and makers. Two-phase head and torque of three centrifugal pumps in high temperature and high pressure (around 6 MPa) steam/water were measured. Head was decreased from single-phase characteristics when gas was mixed in liquid flow in condition with normal flow and normal rotation directions. When flow rate was large enough, two-phase head was about the same as single-phase one in reversal flow conditions. Two-phase head was smoothly increased as flowing steam volumetic concentration increased when flow rate was small and flow direction was reversal. Changes of torque with gas concentration were correspondent to those of head. This suggested that changes of interaction between flow and impellers due to phase slip effected on torque which caused head differences between single- and two-phase flows. Dependence of dimensionless head and torque of three test pumps on steam concentration were almost the same as each other. (author)
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Momentum Confinement at Low Torque
International Nuclear Information System (INIS)
Solomon, W.M.; Burrell, K.H.; deGrassie, J.S.; Budny, R.; Groebner, R.J.; Heidbrink, W.W.; Kinsey, J.E.; Kramer, G.J.; Makowski, M.A.; Mikkelsen, D.; Nazikian, R.; Petty, C.C.; Politzer, P.A.; Scott, S.D.; Van Zeeland, M.A.; Zarnstorff, M.C.
2007-01-01
Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized β N , by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co-neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q min show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. The relative importance of E x B shearing between the two is modeled using GLF23 and may suggest a possible explanation.
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Electromagnetic torque on the toroidal plasma and the error-field induced torque
International Nuclear Information System (INIS)
Pustovitov, V. D.
2007-01-01
The electromagnetic torque on the toroidal plasma is calculated assuming a linear plasma response to the applied perturbation, which may be the error field or the field created by the correction coils, or both. The result is compared with recently published expressions for the error field induced torque (Zheng et al 2006 Nucl. Fusion 46 L9, Zheng and Kotschenreuther 2006 Phys. Rev. Lett. 97 165001), and the conclusions of these papers are revised. We resolve the problem of the torque resonance raised there. It is shown that the strong increase in the torque due to the static error field must occur at the resistive wall mode stability limit and not at the no-wall stability limit
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Thermomagnetic torque in hydrogen isotopes
International Nuclear Information System (INIS)
Cramer, J.A.
1975-01-01
The thermomagnetic torque has been measured in parahydrogen and ortho and normal deuterium for pressures from 0.10 to 2.0 torr and temperatures from 100 to 370 K. Since the torque depends on the precession of the molecular rotational magnetic moment around the field direction, coupling of the molecular nuclear spin to the rotational moment can affect the torque. Evidence of spin coupling effects is found for the torque in both deuterium modifications. In para hydrogen the torque at all temperatures and pressures exhibits behavior expected of a gas of zero nuclear spin molecules. Additionally, earlier data for hydrogen deuteride and for normal hydrogen from 105 to 374 K are evaluated and discussed. The high pressure limiting values of torque peak heights and positions for all these gases are compared with theory
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Bar-On, L.; Desloovere, K.; Molenaers, G.; Harlaar, J.; Kindt, T.; Aertbelien, E.
2014-01-01
Clinical assessment of spasticity is compromised by the difficulty to distinguish neural from non-neural components of increased joint torque. Quantifying the contributions of each of these components is crucial to optimize the selection of anti-spasticity treatments such as botulinum toxin (BTX).
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Buckner, Samuel L; Jenkins, Nathaniel D M; Costa, Pablo B; Ryan, Eric D; Herda, Trent J; Cramer, Joel T
2015-05-01
The purpose of the present study was to compare the passive angle-torque curves and the passive stiffness (PS, N m °(-)(1)) values recorded simultaneously from a load cell versus an isokinetic dynamometer during dorsiflexion stretch tolerance assessments in vivo. Nine healthy men (mean ± SD age = 21.4 ± 1.6 years) completed stretch tolerance assessments on a custom-built apparatus where passive torque was measured simultaneously from an isokinetic dynamometer and a load cell. Passive torque values that corresponded with the last 10° of dorsiflexion, verified by surface electromyographic amplitude, were analyzed for each device (θ1, θ2, θ3, …, θ10). Passive torque values measured with the load cell were greater (p ≤ 0.05) than the dynamometer torque values for θ4 through θ10. There were more statistical differentiations among joint angles for passive torque measured by the load cell, and the load cell measured a greater (p ≤ 0.01) increase in passive torque and PS than the isokinetic dynamometer. These findings suggested that when examining the angle-torque curves from passive dorsiflexion stretch tolerance tests, a load cell placed under the distal end of the foot may be more sensitive than the torque recorded from an isokinetic dynamometer. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.
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Stirling, Leia; Ahmad, Mona Qureshi; Kelty-Stephen, Damian; Correia, Annette
2015-12-16
Many activities of daily living involve precision grasping and bimanual manipulation, such as putting toothpaste on a toothbrush or feeding oneself. However, children afflicted by stroke, cerebral palsy, or traumatic brain injury may have lost or never had the ability to actively and accurately control the thumb. To translate insights from adult rehabilitation robotics to innovative therapies for hand rehabilitation in pediatric care, specifically for thumb deformities, an understanding of the torque needed to abduct the thumb to assist grasping tasks is required. Participants (n=16, 10 female, 13.2±3.1 years) had an upper extremity evaluation and measures were made of their passive range of motion, anthropometrics, and torques to abduct the thumb for both their affected and non-affected sides. Torque measures were made using a custom wrist orthosis that was adjusted for each participant. The torque to achieve maximum abduction was 1.47±0.61inlb for the non-affected side and 1.51±0.68inlb for the affected side, with a maximum recorded value of 4.87inlb. The overall maximum applied torque was observed during adduction and was 5.10inlb. We saw variation in the applied torque, which could have been due to the applied torques by the Occupational Therapist or the participant actively assisting or resisting the motion rather than remaining passive. We expect similar muscle and participant variation to exist with an assistive device. Thus, the data presented here can be used to inform the specifications for the development of an assistive thumb orthosis for children with "thumb-in-palm" deformity. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Peeters, Geeske; Edwards, Kimberley L; Brown, Wendy J; Barker, Anna L; Arden, Nigel; Redmond, Anthony C; Conaghan, Philip G; Cicuttini, Flavia; Mishra, Gita D
2017-12-06
To examine whether body mass index (BMI), menopausal status and hormone therapy (HT) use modify the association between physical activity (PA) patterns throughout middle age and incidence and prevalence of joint symptoms in later middle age in women. Data were from 6661 participants (born 1946-1951) in the Australian Longitudinal Study on Women's Health. Surveys were completed every three years from 1998 to 2010 with questions on joint pain and stiffness, PA, height and weight, menopausal symptoms, and HT use. PA patterns were defined as 'none-or-low', 'low-or-meeting-guidelines', 'fluctuating' or 'meeting guidelines-at-all-times' (reference pattern). Logistic regression was used to examine the association between PA patterns and prevalent (in 2010) and cumulative incident (1998-2010) joint symptoms and effect modification by patterns of BMI, menopausal status and HT. The groups representing 'fluctuating' (odds ratio [OR]=1.34, 99% confidence interval [CI]=1.04-1.72) and 'none-or-low' physical activity (OR=1.60, CI =1.08-2.35) had higher odds of incident joint symptoms than those 'meeting guidelines-at-all-times'. Stratification by BMI showed that this association was statistically significant in the obese group only. No evidence was found for effect modification by menopausal status or HT use. The findings were similar for prevalent joint symptoms. Maintaining at least low levels of physical activity throughout middle age was associated with lower prevalence and incidence of joint symptoms in later life. This apparent protective effect of physical activity on joint symptoms was stronger in obese women than in under or normal weight women, and not related to menopause and HT status. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Li, Jingwen; Ye, Qing; Ding, Li; Liao, Qianfang
2017-07-01
Extravehicular activity (EVA) is an inevitable task for astronauts to maintain proper functions of both the spacecraft and the space station. Both experimental research in a microgravity simulator (e.g. neutral buoyancy tank, zero-g aircraft or a drop tower/tube) and mathematical modeling were used to study EVA to provide guidance for the training on Earth and task design in space. Modeling has become more and more promising because of its efficiency. Based on the task analysis, almost 90% of EVA activity is accomplished through upper limb motions. Therefore, focusing on upper limb models of the body and space suit is valuable to this effort. In previous modeling studies, some multi-rigid-body systems were developed to simplify the human musculoskeletal system, and the space suit was mostly considered as a part of the astronaut body. With the aim to improve the reality of the models, we developed an astronauts' upper limb model, including a torque model and a muscle-force model, with the counter torques from the space suit being considered as a boundary condition. Inverse kinematics and the Maggi-Kane's method was applied to calculate the joint angles, joint torques and muscle force given that the terminal trajectory of upper limb motion was known. Also, we validated the muscle-force model using electromyogram (EMG) data collected in a validation experiment. Muscle force calculated from our model presented a similar trend with the EMG data, supporting the effectiveness and feasibility of the muscle-force model we established, and also, partially validating the joint model in kinematics aspect.
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Adaptive Engine Torque Compensation with Driveline Model
Directory of Open Access Journals (Sweden)
Park Jinrak
2018-01-01
Full Text Available Engine net torque is the total torque generated by the engine side, and includes the fuel combustion torque, the friction torque, and additionally the starter motor torque in case of hybrid vehicles. The engine net torque is utilized to control powertrain items such as the engine itself, the transmission clutch, also the engine clutch, and it must be accurate for the precise powertrain control. However, this net torque can vary with the engine operating conditions like the engine wear, the changes of the atmospheric pressure and the friction torque. Thus, this paper proposes the adaptive engine net torque compensator using driveline model which can cope with the net torque change according to engine operating conditions. The adaptive compensator was applied on the parallel hybrid vehicle and investigated via MATLAB Simcape Driveline simulation.
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Latash, M L; Goodman, S R
1994-01-01
The purpose of this work has been to develop a model of electromyographic (EMG) patterns during single-joint movements based on a version of the equilibrium-point hypothesis, a method for experimental reconstruction of the joint compliant characteristics, the dual-strategy hypothesis, and a kinematic model of movement trajectory. EMG patterns are considered emergent properties of hypothetical control patterns that are equally affected by the control signals and peripheral feedback reflecting actual movement trajectory. A computer model generated the EMG patterns based on simulated movement kinematics and hypothetical control signals derived from the reconstructed joint compliant characteristics. The model predictions have been compared to published recordings of movement kinematics and EMG patterns in a variety of movement conditions, including movements over different distances, at different speeds, against different-known inertial loads, and in conditions of possible unexpected decrease in the inertial load. Changes in task parameters within the model led to simulated EMG patterns qualitatively similar to the experimentally recorded EMG patterns. The model's predictive power compares it favourably to the existing models of the EMG patterns. Copyright © 1994. Published by Elsevier Ltd.
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40 CFR 1065.310 - Torque calibration.
2010-07-01
... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Torque calibration. 1065.310 Section... Conditions § 1065.310 Torque calibration. (a) Scope and frequency. Calibrate all torque-measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after major...
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Liu, Yali; Hong, Yuezhen; Ji, Linhong
2018-01-01
Patients with hemiplegia usually have weak muscle selectivity and usually perform strength at a secondary joint (secondary strength) during performing a strength at one joint (primary strength). The abnormal strength pattern between shoulder and elbow joint has been analyzed by the maximum value while the performing process with strength changing from 0 to maximum then to 0 was a dynamic process. The objective of this study was to develop a method to dynamically analyze the strength changing process. Ten patients were asked to perform four group asks (maximum and 50% maximum voluntary strength in shoulder abduction, shoulder adduction, elbow flexion, and elbow extension). Strength and activities from seven muscles were measured. The changes of secondary strength had significant correlation with those of primary strength in all tasks ( R > 0.76, p strength ( R > 0.4, p strength pattern (all p strength pattern. The muscles, deltoid muscles, biceps brachii, triceps brachii, and brachioradialis, much influenced the stereotyped movement pattern between shoulder and elbow joint.
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Installation Torque Tables for Noncritical Applications
Rivera-Rosario, Hazel T.; Powell, Joseph S.
2017-01-01
The objective of this project is to define torque values for bolts and screws when loading is not a concern. Fasteners require a certain torque to fulfill its function and prevent failure. NASA Glenn Research Center did not have a set of fastener torque tables for non-critical applications without loads, usually referring to hand-tight or wrench-tight torqueing. The project is based on two formulas, torque and pullout load. Torque values are calculated giving way to preliminary data tables. Testing is done to various bolts and metal plates, torqueing them until the point of failure. Around 640 torque tables were developed for UNC, UNF, and M fasteners. Different lengths of thread engagement were analyzed for the 5 most common materials used at GRC. The tables were put together in an Excel spreadsheet and then formatted into a Word document. The plan is to later convert this to an official technical publication or memorandum.
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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 (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.
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14 CFR 27.361 - Engine torque.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for maximum...
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Glaviano, Neal R; Langston, William T; Hart, Joseph M; Saliba, Susan
2014-12-01
Neuromuscular Electrical Stimulation is a common intervention to address muscle weakness, however presents with many limitations such as fatigue, muscle damage, and patient discomfort that may influence its effectiveness. One novel form of electrical stimulation purported to improve neuromuscular re-education is Patterned Electrical Neuromuscular Stimulation (PENS), which is proposed to mimic muscle-firing patterns of healthy individuals. PENS provides patterned stimulating to the agonist muscle, antagonist muscle and then agonist muscle again in an effort to replicate firing patterns. The purpose of this study was to determine the effect of a single PENS treatment on knee extension torque and quadriceps activation in individuals with quadriceps inhibition. 18 subjects (10 males and 8 females: 24.2±3.4 years, 175.3±11.8cm, 81.8±12.4kg) with a history of knee injury/pain participated in this double-blinded randomized controlled laboratory trial. Participants demonstrated quadriceps inhibition with a central activation ratio of ≤90%. Maximal voluntary isometric contraction of the quadriceps and central activation ratio were measured before and after treatment. The treatment intervention was a 15-minute patterned electrical stimulation applied to the quadriceps and hamstring muscles with a strong motor contraction or a sham group, who received an identical set up as the PENS group, but received a 1mA subsensory stimulation. A 2×2 (group × time) ANCOVA was used to determine differences in maximal voluntary isometric contraction and central activation ratio between groups. The maximal voluntary isometric contraction was selected as a covariate due to baseline differences. There were no differences in change scores between pre- and post-intervention for maximal voluntary isometric contraction: (PENS: 0.09±0.32Nm/kg and Sham 0.15±0.18Nm/kg, p=0.713), or central activation ratio:(PENS: -1.22±6.06 and Sham: 1.48±3.7, p=0.270). A single Patterned Electrical
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Measurement of Resistive Torques in Major Human Joints
1979-04-01
was assisted by the following graduate students whose names, in the order of the magnitude of their contributions, are: Richard D. Peindl, Manssour...acknowledged by the author, a considerable addi- tional time investment was made by the principal investigator and several graduate students to complete the...Conaill, M.A., "Joint Movement," Physiotherapy (50), 359, 1964. 17. Murphy, W.W., Garcia, D.H. and Bird, R.G., "Measurement of Body Motion," ASME
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Charge-induced spin torque in Weyl semimetals
Kurebayashi, Daichi; Nomura, Kentaro
In this work, we present phenomenological and microscopic derivations of spin torques in magnetically doped Weyl semimetals. As a result, we obtain the analytical expression of the spin torque generated, without a flowing current, when the chemical potential is modulated. We also find that this spin torque is a direct consequence of the chiral anomaly. Therefore, observing this spin torque in magnetic Weyl semimetals might be an experimental evidence of the chiral anomaly. This spin torque has also a great advantage in application. In contrast to conventional current-induced spin torques such as the spin-transfer torques, this spin torque does not accompany a constant current flow. Thus, devices using this operating principle is free from the Joule heating and possibly have higher efficiency than devices using conventional current-induced spin torques. This work was supported by JSPS KAKENHI Grant Number JP15H05854 and JP26400308.
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Bates, Nathaniel A.; Nesbitt, Rebecca J.; Shearn, Jason T.; Myer, Gregory D.; Hewett, Timothy E.
2017-01-01
Background Tibial slope angle is a nonmodifiable risk factor for anterior cruciate ligament (ACL) injury. However, the mechanical role of varying tibial slopes during athletic tasks has yet to be clinically quantified. Purpose To examine the influence of posterior tibial slope on knee joint loading during controlled, in vitro simulation of the knee joint articulations during athletic tasks. Study Design Descriptive laboratory study. Methods A 6 degree of freedom robotic manipulator positionally maneuvered cadaveric knee joints from 12 unique specimens with varying tibial slopes (range, −7.7° to 7.7°) through drop vertical jump and sidestep cutting tasks that were derived from 3-dimensional in vivo motion recordings. Internal knee joint torques and forces were recorded throughout simulation and were linearly correlated with tibial slope. Results The mean (6SD) posterior tibial slope angle was 2.2° ± 4.3° in the lateral compartment and 2.3° ± 3.3° in the medial compartment. For simulated drop vertical jumps, lateral compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee adduction (r = 0.60–0.65), flexion (r = 0.64–0.66), lateral (r = 0.57–0.69), and external rotation torques (r = 0.47–0.72) as well as inverse correlations with peak abduction (r = −0.42 to −0.61) and internal rotation torques (r = −0.39 to −0.79). Only frontal plane torques were correlated during sidestep cutting simulations. For simulated drop vertical jumps, medial compartment tibial slope angle expressed moderate, direct correlations with peak internally generated knee flexion torque (r = 0.64–0.69) and lateral knee force (r = 0.55–0.74) as well as inverse correlations with peak external torque (r = −0.34 to 20.67) and medial knee force (r = −0.58 to −0.59). These moderate correlations were also present during simulated sidestep cutting. Conclusion The investigation supported the theory that increased posterior
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Spin Orbit Torque in Ferromagnetic Semiconductors
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
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Estimation of Human Hip and Knee Multi-Joint Dynamics Using the LOPES Gait Trainer
Koopman, Hubertus F.J.M.; van Asseldonk, Edwin H.F.; van der Kooij, Herman
2016-01-01
In this study, we present and evaluate a novel method to estimate multi-joint leg impedance, using a robotic gait training device. The method is based on multi-input–multi-output system identification techniques and is designed for continuous torque perturbations at the hip and knee joint
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Davidson, J A; Schwartz, G; Lynch, G; Gir, S
1988-04-01
In Part I, (J.A. Davidson and G. Schwartz, "Wear, creep, and frictional heating of femoral implant articulating surfaces and the effect on long-term performance--Part I, A review," J. Biomed. Mater. Res., 21, 000-000 (1987) it was shown that lubrication of the artificial hip joint was complex and that long-term performance is governed by the combined wear, creep, and to a lesser extent, oxidation degradation of the articulating materials. Importantly, it was shown that a tendency for heating exists during articulation in the hip joint and that elevated temperatures can increase the wear, creep, and oxidation degradation rate of UHMWPE. The present study was performed to examine closely the propensity to generate heat during articulation in a hip joint simulator. The systems investigated were polished Co-Cr-Mo alloy articulating against UHMWPE, polished alumina ceramic against UHMWPE, and polished alumina against itself. Frictional torque was also evaluated for each system at various levels of applied loads. A walking load history was used in both the frictional heating and torque tests. The majority of tests were performed with 5 mL of water lubricant. However, the effect of various concentrations of hyaluronic acid was also evaluated. Results showed frictional heating to occur in all three systems, reaching an equilibrium after roughly 30 min articulation time. Ceramic systems showed reduced levels of heating compared to the cobalt alloy-UHMWPE system. The level of frictional torque for each system ranked similar to their respective tendencies to generate heat. Hyaluronic acid had little effect, while dry conditions and the presence of small quantities of bone cement powder in water lubricant significantly increased frictional torque.
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Directory of Open Access Journals (Sweden)
Aiman Omer
2015-12-01
Full Text Available Bipedal humanoid robots are expected to play a major role in the future. Performing bipedal locomotion requires high energy due to the high torque that needs to be provided by its legs’ joints. Taking the WABIAN-2R as an example, it uses harmonic gears in its joint to increase the torque. However, using such a mechanism increases the weight of the legs and therefore increases energy consumption. Therefore, the idea of developing a mechanism with adjustable stiffness to be connected to the leg joint is introduced here. The proposed mechanism would have the ability to provide passive and active motion. The mechanism would be attached to the ankle pitch joint as an artificial tendon. Using computer simulations, the dynamical performance of the mechanism is analytically evaluated.
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Experimental study of friction in aluminium bolted joints
Croccolo, D.; de Agostinis, M.; Vincenzi, N.
2010-06-01
This study aims at developing an experimental tool useful to define accurately the friction coefficients in bolted joints and, therefore, at relating precisely the tightening torque to the bolt preloading force in some special components used in front motorbike suspensions. The components under investigation are some clamped joints made of aluminium alloy. The preloading force is achieved by applying a torque wrench to the bolt head. Some specific specimens have been appropriately designed and realized in order to study the tribological aspects of the tightening phase. Experimental tests have been performed by applying the Design of Experiment (DOE) method in order to obtain a mathematical model for the friction coefficients. Three replicas of a full factorial DOE at two levels for each variable have been carried out. The levels include cast versus forged aluminium alloy, anodized versus spray-painted surface, lubricated versus unlubricated screw, and first tightening (fresh unspoiled surfaces) versus sixth tightening (spoiled surfaces). The study considers M8x1.25 8.8 galvanized screws.
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Oh, Keonyoung; Park, Sukyung
2017-02-28
A local minimum for running energetics has been reported for a specific bending stiffness, implying that shoe stiffness assists in running propulsion. However, the determinant of the metabolic optimum remains unknown. Highly stiff shoes significantly increase the moment arm of the ground reaction force (GRF) and reduce the leverage effect of joint torque at ground push-off. Inspired by previous findings, we hypothesized that the restriction of the natural metatarsophalangeal (MTP) flexion caused by stiffened shoes and the corresponding joint torque changes may reduce the benefit of shoe bending stiffness to running energetics. We proposed the critical stiffness, k cr , which is defined as the ratio of the MTP joint (MTPJ) torque to the maximal MTPJ flexion angle, as a possible threshold of the elastic benefit of shoe stiffness. 19 subjects participated in a running test while wearing insoles with five different bending stiffness levels. Joint angles, GRFs, and metabolic costs were measured and analyzed as functions of the shoe stiffness. No significant changes were found in the take-off velocity of the center of mass (CoM), but the horizontal ground push-offs were significantly reduced at different shoe stiffness levels, indicating that complementary changes in the lower-limb joint torques were introduced to maintain steady running. Slight increases in the ankle, knee, and hip joint angular impulses were observed at stiffness levels exceeding the critical stiffness, whereas the angular impulse at the MTPJ was significantly reduced. These results indicate that the shoe bending stiffness is beneficial to running energetics if it does not disturb the natural MTPJ flexion. Copyright © 2017 Elsevier Ltd. All rights reserved.
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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...
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Self-healing bolted joint employing a shape memory actuator
Muntges, Daniel E.; Park, Gyuhae; Inman, Daniel J.
2001-08-01
This paper is a report of an initial investigation into the active control of preload in the joint using a shape memory actuator around the axis of the bolt shaft. Specifically, the actuator is a cylindrical Nitinol washer that expands axially when heated, according to the shape memory effect. The washer is actuated in response to an artificial decrease in torque. Upon actuation, the stress generated by its axial strain compresses the bolted members and creates a frictional force that has the effect of generating a preload and restoring lost torque. In addition to torque wrenches, the system in question was monitored in all stages of testing using piezoelectric impedance analysis. Impedance analysis drew upon research techniques developed at Center for Intelligent Material Systems and Structures, in which phase changes in the impedance of a self-sensing piezoceramic actuator correspond to changes in joint stiffness. Through experimentation, we have documented a successful actuation of the shape memory element. Due to complexity of constitutive modeling, qualitative analysis by the impedance method is used to illustrate the success. Additional considerations encountered in this initial investigation are made to guide further thorough research required for the successful commercial application of this promising technique.
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Directory of Open Access Journals (Sweden)
Ai Mizuno
2018-02-01
Full Text Available Spherical ultrasonic motors (SUSMs that can operate with multiple degrees of freedom (MDOF using only a single stator have high holding torque and high torque at low speed, which makes reduction gearing unnecessary. The simple structure of MDOF-SUSMs makes them useful as compact actuators, but their development is still insufficient for applications such as joints of humanoid robots and other systems that require MDOF and high torque. To increase the torque of a sandwich-type MDOF-SUSM, we have not only made the vibrating stator and spherical rotor larger but also improved the structure using three design concepts: (1 increasing the strength of all three vibration modes using multilayered piezoelectric actuators (MPAs embedded in the stator, (2 enhancing the rigidity of the friction driving portion of the stator for transmitting more vibration force to the friction-driven rotor surface, and (3 making the support mechanism more stable. An MDOF-SUSM prototype was tested, and the maximum torques of rotation around the X(Y-axis and Z-axis were measured as 1.48 N∙m and 2.05 N∙m, respectively. Moreover, the values for torque per unit weight of the stator were obtained as 0.87 N∙m/kg for the X(Y-axis and 1.20 N∙m/kg for the Z-axis. These are larger than values reported for any other sandwich-type MDOF-SUSM of which we are aware. Hence, the new design concepts were shown to be effective for increasing torque. In addition, we measured the transient response and calculated the load characteristics of rotation around the rotor’s three orthogonal axes.
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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
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Development of a Portable Torque Wrench Tester
Wang, Y.; Zhang, Q.; Gou, C.; Su, D.
2018-03-01
A portable torque wrench tester (PTWT) with calibration range from 0.5 Nm to 60 Nm has been developed and evaluated for periodic or on-site calibration of setting type torque wrenches, indicating type torque wrenches and hand torque screwdrivers. The PTWT is easy to carry with weight about 10 kg, simple and efficient operation and energy saving with an automatic loading and calibrating system. The relative expanded uncertainty of torque realized by the PTWT was estimated to be 0.8%, with the coverage factor k=2. A comparison experiment has been done between the PTWT and a reference torque standard at our laboratory. The consistency between these two devices under the claimed uncertainties was verified.
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Optimized bolt tightening strategies for gasketed flanged pipe joints of different sizes
International Nuclear Information System (INIS)
Abid, Muhammad; Khan, Ayesha; Nash, David Hugh; Hussain, Masroor; Wajid, Hafiz Abdul
2016-01-01
Achieving a proper preload in the bolts of a gasketed bolted flanged pipe joint during joint assembly is considered important for its optimized performance. This paper presents results of detailed non-linear finite element analysis of an optimized bolt tightening strategy of different joint sizes for achieving proper preload close to the target stress values. Industrial guidelines are considered for applying recommended target stress values with TCM (torque control method) and SCM (stretch control method) using a customized optimization algorithm. Different joint components performance is observed and discussed in detail.
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14 CFR 23.361 - Engine torque.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 23.361 Section 23.361... Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque corresponding to takeoff power and propeller speed acting simultaneously with...
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14 CFR 25.361 - Engine torque.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 25.361 Section 25.361... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Supplementary Conditions § 25.361 Engine torque. (a) Each engine mount and its supporting structure must be designed for the effects of— (1) A limit engine torque...
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Torque limit of PM motors for field-weakening region operation
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.
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Design and Vibration Suppression Control of a Modular Elastic Joint
Directory of Open Access Journals (Sweden)
Hong Liu
2018-06-01
Full Text Available In this paper, a novel mechatronic design philosophy is introduced to develop a compact modular rotary elastic joint for a humanoid manipulator. The designed elastic joint is mainly composed of a brushless direct current (DC motor, harmonic reducer, customized torsional spring, and fail-safe brake. The customized spring considerably reduces the volume of the elastic joint and facilitates the construction of a humanoid manipulator which employs this joint. The large central hole along the joint axis brings convenience for cabling and the fail-safe brake can guarantee safety when the power is off. In order to reduce the computational burden on the central controller and simplify system maintenance, an expandable electrical system, which has a double-layer control structure, is introduced. Furthermore, a robust position controller for the elastic joint is proposed and interpreted in detail. Vibration of the elastic joint is suppressed by means of resonance ratio control (RRC. In this method, the ratio between the resonant and anti-resonant frequency can be arbitrarily designated according to the feedback of the nominal spring torsion. Instead of using an expensive torque sensor, the spring torque can be obtained by calculating the product of spring stiffness and deformation, due to the high linearity of the customized spring. In addition, to improve the system robustness, a motor-side disturbance observer (DOb and an arm-side DOb are employed to estimate and compensate for external disturbances and system uncertainties, such as model variation, friction, and unknown external load. Validity of the DOb-based RRC is demonstrated in the simulation results. Experimental results show the performance of the modular elastic joint and the viability of the proposed controller further.
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14 CFR 29.361 - Engine torque.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 29.361 Section 29.361... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 29.361 Engine torque. The limit engine torque may not be less than the following: (a) For turbine engines, the highest of— (1) The...
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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
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Directory of Open Access Journals (Sweden)
Yali Liu
2018-01-01
Full Text Available Patients with hemiplegia usually have weak muscle selectivity and usually perform strength at a secondary joint (secondary strength during performing a strength at one joint (primary strength. The abnormal strength pattern between shoulder and elbow joint has been analyzed by the maximum value while the performing process with strength changing from 0 to maximum then to 0 was a dynamic process. The objective of this study was to develop a method to dynamically analyze the strength changing process. Ten patients were asked to perform four group asks (maximum and 50% maximum voluntary strength in shoulder abduction, shoulder adduction, elbow flexion, and elbow extension. Strength and activities from seven muscles were measured. The changes of secondary strength had significant correlation with those of primary strength in all tasks (R>0.76, p0.4, p<0.01. Deltoid muscles, biceps brachii, triceps brachii, and brachioradialis had significant influences on the abnormal strength pattern (all p<0.01. The dynamic method was proved to be efficient to analyze the different influences of muscles on the abnormal strength pattern. The muscles, deltoid muscles, biceps brachii, triceps brachii, and brachioradialis, much influenced the stereotyped movement pattern between shoulder and elbow joint.
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Kihlberg, S; Kjellberg, A; Lindbeck, L
1993-06-01
Reaction forces, hand-arm displacement, muscle activity and discomfort ratings were studied during the securing of threaded fasteners with three angle nutrunners with different shut-off mechanisms, but with the same spindle torque (72-74 Nm). The three tools were tested according to the method specified in ISO 6544. One of the tools had an almost instantaneous shut-off. Another had a more slowly declining torque curve. For the third tool the maximum torque was maintained for a while before shut-off. Twelve male subjects participated in the study. A force platform measured the reaction force between the subject and the floor. The option of the hand-arm system and the shoulder was measured with an optoelectronic measuring system. The muscle activity (EMG) in six muscles in the arm and shoulder was measured with surface electrodes. Significant differences in the arm movements and ground reaction forces were found between the three tools. The smallest values were found with the fast shut-off tool while the delayed shut-off tool caused the largest values. The EMG measures gave inconsistent response patterns. Discomfort ratings were highly correlated with the time for which the tool torque exceeded 90% of peak preset torque, but the time for which the tool torque exceeded 90% of peak calculated by the method specified in ISO 6544. Nutrunners with a shut-off mechanism that causes a slowly decreasing torque or a torque that is maintained for a while before shut-off should be avoided. If no substitutes are available, then a torque reaction bar should be mounted on the tool.
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The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures
Grollier, Julie
2013-03-01
Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.
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Jalaleddini, Kian; Tehrani, Ehsan Sobhani; Kearney, Robert E
2017-06-01
The purpose of this paper is to present a structural decomposition subspace (SDSS) method for decomposition of the joint torque to intrinsic, reflexive, and voluntary torques and identification of joint dynamic stiffness. First, it formulates a novel state-space representation for the joint dynamic stiffness modeled by a parallel-cascade structure with a concise parameter set that provides a direct link between the state-space representation matrices and the parallel-cascade parameters. Second, it presents a subspace method for the identification of the new state-space model that involves two steps: 1) the decomposition of the intrinsic and reflex pathways and 2) the identification of an impulse response model of the intrinsic pathway and a Hammerstein model of the reflex pathway. Extensive simulation studies demonstrate that SDSS has significant performance advantages over some other methods. Thus, SDSS was more robust under high noise conditions, converging where others failed; it was more accurate, giving estimates with lower bias and random errors. The method also worked well in practice and yielded high-quality estimates of intrinsic and reflex stiffnesses when applied to experimental data at three muscle activation levels. The simulation and experimental results demonstrate that SDSS accurately decomposes the intrinsic and reflex torques and provides accurate estimates of physiologically meaningful parameters. SDSS will be a valuable tool for studying joint stiffness under functionally important conditions. It has important clinical implications for the diagnosis, assessment, objective quantification, and monitoring of neuromuscular diseases that change the muscle tone.
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Angular Acceleration without Torque?
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.
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Invariant ankle moment patterns when walking with and without a robotic ankle exoskeleton.
Kao, Pei-Chun; Lewis, Cara L; Ferris, Daniel P
2010-01-19
To guide development of robotic lower limb exoskeletons, it is necessary to understand how humans adapt to powered assistance. The purposes of this study were to quantify joint moments while healthy subjects adapted to a robotic ankle exoskeleton and to determine if the period of motor adaptation is dependent on the magnitude of robotic assistance. The pneumatically powered ankle exoskeleton provided plantar flexor torque controlled by the wearer's soleus electromyography (EMG). Eleven naïve individuals completed two 30-min sessions walking on a split-belt instrumented treadmill at 1.25m/s while wearing the ankle exoskeleton. After two sessions of practice, subjects reduced their soleus EMG activation by approximately 36% and walked with total ankle moment patterns similar to their unassisted gait (r(2)=0.98+/-0.02, THSD, p>0.05). They had substantially different ankle kinematic patterns compared to their unassisted gait (r(2)=0.79+/-0.12, THSD, probotic ankle exoskeleton (Gordon and Ferris, 2007). Our results strongly suggest that humans aim for similar joint moment patterns when walking with robotic assistance rather than similar kinematic patterns. In addition, greater robotic assistance provided during initial use results in a longer adaptation process than lesser robotic assistance. Copyright 2009 Elsevier Ltd. All rights reserved.
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EMG-Torque Dynamics Change With Contraction Bandwidth.
Golkar, Mahsa A; Jalaleddini, Kian; Kearney, Robert E
2018-04-01
An accurate model for ElectroMyoGram (EMG)-torque dynamics has many uses. One of its applications which has gained high attention among researchers is its use, in estimating the muscle contraction level for the efficient control of prosthesis. In this paper, the dynamic relationship between the surface EMG and torque during isometric contractions at the human ankle was studied using system identification techniques. Subjects voluntarily modulated their ankle torque in dorsiflexion direction, by activating their tibialis anterior muscle, while tracking a pseudo-random binary sequence in a torque matching task. The effects of contraction bandwidth, described by torque spectrum, on EMG-torque dynamics were evaluated by varying the visual command switching time. Nonparametric impulse response functions (IRF) were estimated between the processed surface EMG and torque. It was demonstrated that: 1) at low contraction bandwidths, the identified IRFs had unphysiological anticipatory (i.e., non-causal) components, whose amplitude decreased as the contraction bandwidth increased. We hypothesized that this non-causal behavior arose, because the EMG input contained a component due to feedback from the output torque, i.e., it was recorded from within a closed-loop. Vision was not the feedback source since the non-causal behavior persisted when visual feedback was removed. Repeating the identification using a nonparametric closed-loop identification algorithm yielded causal IRFs at all bandwidths, supporting this hypothesis. 2) EMG-torque dynamics became faster and the bandwidth of system increased as contraction modulation rate increased. Thus, accurate prediction of torque from EMG signals must take into account the contraction bandwidth sensitivity of this system.
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Advances towards high performance low-torque qmin > 2 operations with large-radius ITB on DIII-D
Xu, G. S.; Solomon, W. M.; Garofalo, A. M.; Ferron, J. R.; Hyatt, A. W.; Wang, Q.; Yan, Z.; McKee, G. R.; Holcomb, C. T.; EAST Team
2015-11-01
A joint DIII-D/EAST experiment was performed aimed at extending a fully noninductive scenario with high βP and qmin > 2 to inductive operation at lower torque and higher Ip (0.6 --> 0.8 MA) for better performance. Extremely high confinement was obtained, i.e., H98y2 ~ 2.1 at βN ~ 3, which was associated with a strong ITB at large minor radius (ρ ~ 0.7). Alfvén Eigenmodes and broadband turbulence were significantly suppressed in the core, and fast-ion confinement was improved. ITB collapses at 0.8 MA were induced by ELM-triggered n = 1 MHD modes at the ITB location, which is different from the ``relaxation oscillations'' associated with the steady-state plasmas at lower current (0.6 MA). This successful joint experiment may open up a new avenue towards high performance low-torque qmin > 2 plasmas with large-radius ITBs, which will be demonstrated on EAST in the near future. Work supported by NMCFSP 2015GB102000, 2015GB110001 and the US DOE under DE-AC02-09CH11466, DE-FC02-04ER54698, DE-FG02-89ER53296 and DE-AC52-07NA27344.
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Muscle response to pneumatic hand tool torque reaction forces.
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
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Goetschius, John; Hart, Joseph M
2016-01-01
When returning to physical activity, patients with a history of anterior cruciate ligament reconstruction (ACL-R) often experience limitations in knee-joint function that may be due to chronic impairments in quadriceps motor control. Assessment of knee-extension torque variability may demonstrate underlying impairments in quadriceps motor control in patients with a history of ACL-R. To identify differences in maximal isometric knee-extension torque variability between knees that have undergone ACL-R and healthy knees and to determine the relationship between knee-extension torque variability and self-reported knee function in patients with a history of ACL-R. Descriptive laboratory study. Laboratory. A total of 53 individuals with primary, unilateral ACL-R (age = 23.4 ± 4.9 years, height = 1.7 ± 0.1 m, mass = 74.6 ± 14.8 kg) and 50 individuals with no history of substantial lower extremity injury or surgery who served as controls (age = 23.3 ± 4.4 years, height = 1.7 ± 0.1 m, mass = 67.4 ± 13.2 kg). Torque variability, strength, and central activation ratio (CAR) were calculated from 3-second maximal knee-extension contraction trials (90° of flexion) with a superimposed electrical stimulus. All participants completed the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, and we determined the number of months after surgery. Group differences were assessed using independent-samples t tests. Correlation coefficients were calculated among torque variability, strength, CAR, months after surgery, and IKDC scores. Torque variability, strength, CAR, and months after surgery were regressed on IKDC scores using stepwise, multiple linear regression. Torque variability was greater and strength, CAR, and IKDC scores were lower in the ACL-R group than in the control group (P Torque variability and strength were correlated with IKDC scores (P Torque variability, strength, and CAR were correlated with each other (P Torque variability alone
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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...
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Parametric motion control of robotic arms: A biologically based approach using neural networks
Bock, O.; D'Eleuterio, G. M. T.; Lipitkas, J.; Grodski, J. J.
1993-01-01
A neural network based system is presented which is able to generate point-to-point movements of robotic manipulators. The foundation of this approach is the use of prototypical control torque signals which are defined by a set of parameters. The parameter set is used for scaling and shaping of these prototypical torque signals to effect a desired outcome of the system. This approach is based on neurophysiological findings that the central nervous system stores generalized cognitive representations of movements called synergies, schemas, or motor programs. It has been proposed that these motor programs may be stored as torque-time functions in central pattern generators which can be scaled with appropriate time and magnitude parameters. The central pattern generators use these parameters to generate stereotypical torque-time profiles, which are then sent to the joint actuators. Hence, only a small number of parameters need to be determined for each point-to-point movement instead of the entire torque-time trajectory. This same principle is implemented for controlling the joint torques of robotic manipulators where a neural network is used to identify the relationship between the task requirements and the torque parameters. Movements are specified by the initial robot position in joint coordinates and the desired final end-effector position in Cartesian coordinates. This information is provided to the neural network which calculates six torque parameters for a two-link system. The prototypical torque profiles (one per joint) are then scaled by those parameters. After appropriate training of the network, our parametric control design allowed the reproduction of a trained set of movements with relatively high accuracy, and the production of previously untrained movements with comparable accuracy. We conclude that our approach was successful in discriminating between trained movements and in generalizing to untrained movements.
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Directory of Open Access Journals (Sweden)
Shiyuan Hou
2015-01-01
Full Text Available This paper proposed a mathematical model to investigate the radial expansion induced loosening of rectangle thread bolted joints that were subjected to cyclic temperature variation, which could cause slippage between contact pairs of engaged threads and bolt bearing. Firstly, integral equations were derived for the shear stress components caused by expansion difference, as well as the bearing and thread friction torque components, which depended on the temperature variation. Secondly, the relationship of displacement components was developed based on quasi-static hypotheses. Then, treating the rotation of bolt as plastic elongation, the bolt tension's evolution was obtained by using a one-dimensional bolted joint model. Numerical results showed that the temperature variation decreased the bearing and thread friction torque components, which could lead bolted joint to loosen. Finally, the effects of some associated factors on the progress were discussed.
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Immediate vs. delayed endosseous integration of maxi implants: a torque removal animal study
Directory of Open Access Journals (Sweden)
Hanif Allahbakhshi
2017-06-01
Full Text Available Background. Delayed loading is one of the concerns in implant patients. Immediate loading can solve the problem and make patients more satisfied. The present study aimed to compare the removal torque of maxi implants under different loading (immediate and delayed patterns. Methods. This split-mouth experimental study included 2 dogs. Impressions were made and then all the premolars were extracted under general anesthesia. After a three-month healing period, 3 implants were inserted in each quadrant (a total of 12 implants. Anterior and posterior implants (the case group were splinted by an acrylic temporary bridge in order to make the middle implants (the control group off the occlusion. The dogs were sacrificed after 6 weeks and bone blocks were submitted for removal torque test. Data were analyzed with ANOVA (P<0.05. Results. Mean torque values for the cases and control groups were 46.82±25.58 and 59.88±15.19, respectively (P=0.582; not significant. Conclusion. It may be concluded that immediate loading does not reduce the reverse torque values of maxi implants. This supports the advantages of immediate loading for maxi implants.
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Directory of Open Access Journals (Sweden)
Matthias Aurich
2014-12-01
Full Text Available Osteoarthritis (OA is more common in the knee compared to the ankle joint. This can not be explained exclusively by anatomical and biomechanical differences. The aim of this study is to analyze and compare the injury pattern (clinically and the cartilage lesions (arthroscopically of knee and ankle joints in a cohort of patients from the same catchment area. A retrospective study of the clinical data of 3122 patients (2139 outpatients and 983 inpatients was performed, who were treated due to an injury of the knee and ankle joint. Statistical analysis was performed using SigmaStat 3.0 (SPSS Inc, Chicago, USA. There is a higher prevalence of injuries in the ankle as compared to the knee joint in this population from the same catchment area. In contrast, high-grade cartilage lesions are more prevalent in the knee, whereas low grade cartilage lesions are equally distributed between knee and ankle. From this data it can be concluded that the frequency of injuries and the injury pattern of knee versus ankle joints do not correlate with the severity of cartilage lesions and may therefore have no direct influence on the differential incidence of OA in those two joints.
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de Gooijer-van de Groep, Karin L; de Vlugt, Erwin; de Groot, Jurriaan H; van der Heijden-Maessen, Hélène C M; Wielheesen, Dennis H M; van Wijlen-Hempel, Rietje M S; Arendzen, J Hans; Meskers, Carel G M
2013-07-23
Spastic paresis in cerebral palsy (CP) is characterized by increased joint stiffness that may be of neural origin, i.e. improper muscle activation caused by e.g. hyperreflexia or non-neural origin, i.e. altered tissue viscoelastic properties (clinically: "spasticity" vs. "contracture"). Differentiation between these components is hard to achieve by common manual tests. We applied an assessment instrument to obtain quantitative measures of neural and non-neural contributions to ankle joint stiffness in CP. Twenty-three adolescents with CP and eleven healthy subjects were seated with their foot fixated to an electrically powered single axis footplate. Passive ramp-and-hold rotations were applied over full ankle range of motion (RoM) at low and high velocities. Subject specific tissue stiffness, viscosity and reflexive torque were estimated from ankle angle, torque and triceps surae EMG activity using a neuromuscular model. In CP, triceps surae reflexive torque was on average 5.7 times larger (p = .002) and tissue stiffness 2.1 times larger (p = .018) compared to controls. High tissue stiffness was associated with reduced RoM (p therapy.
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International Nuclear Information System (INIS)
Masood, T.; Khan, H.M.M.H.
2017-01-01
To compare the effects of isokinetic and isometric strength trainings on hamstring and quadriceps average-peak-torques, physical performance, and pain. Methodology: Twenty athletes with knee pain were randomly assigned to two equal groups: Isokinetic training and isometric training. Both groups were trained on Biodex System 3 Pro for 10 sessions. Isokinetic-group received isokinetic training on 5 different velocities while isometric-group performed isometric contractions at 3 knee joint angles. Results: Hamstring isokinetic average-peak-torque was significantly higher at all velocities without significant improvement in quadriceps average-peak-torque except for at the slowest velocity. Isometric training did not cause significant change in isometric average-peak-torque at any knee angle for either hamstring or quadriceps. Agility, elastic leg strength, and pain improved significantly in both groups with no significant between-group differences. No significant statistical correlation was observed between pain and any other parameter after either type of training. Conclusions: Athletes participating in sports requiring dynamic hamstring strength should prefer isokinetic strength training for physical rehabilitation of knee pain. However, physical performance and pain can be improved with both isometric and isokinetic strength training. (author)
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DEFF Research Database (Denmark)
Boesen, Mikael; Jensen, Karl Erik; Torp-Pedersen, Søren
2007-01-01
OBJECTIVE: To investigate the distribution of an ultrasound-guided intra-articular (IA) injection in the wrist joint of patients with rheumatoid arthritis (RA). METHODS: An ultrasound-guided IA drug injection into the wrist joint was performed in 17 patients with 1 ml methylprednisolone (40 mg...... with the MRI OMERACT synovitis score (r=0.60, p=0.014), but not with the erosions, bonemarrow oedema scores or any clinical parameters. CONCLUSION: The distribution of contrast on MRI showed patient specific and random patterns after IA injections in active RA wrist joints. The degree of distribution increased...
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International Nuclear Information System (INIS)
Larik, A.S.
2010-01-01
The direct-on-line starting of induction motor draws heavy current and to limit this Inrush current to a safe level normally a star-delta switch is used. However, the switching over from star to delta causes over current transients and this leads to torque pulsations. Therefore, in this paper the current and torque pulsations developed during the switching process are focused and a soft-switched controller is devised to minimize the re-closure transient currents and torque pulsations during star-delta switching of induction motor. The designed system can readily handles the sensing of favorable conditions of re closure of a switched-off running induction motor and it minimizes the inrush current and hence the pulsations of torque of all types of induction motors, whether, single-phase or three phase. An investigation is made into the transient currents and pulsation torques generated due to opening the circuit of a running induction motor and the switching pattern of star-delta switching. The re-switching control scheme for the induction motor is practically tested in the laboratory with and without soft controller. (author)
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Chino, Kintaro; Takashi, Hideyuki
2017-11-15
Passive ankle joint stiffness is affected by all structures located within and over the joint, and is greater in men than in women. Localized muscle stiffness can be assessed by ultrasound shear wave elastography, and muscle architecture such as fascicle length and pennation angle can be measured by B-mode ultrasonography. Thus, we assessed localized muscle stiffness of the medial gastrocnemius (MG) with consideration of individual variability in the muscle architecture, and examined the association of the muscle stiffness with passive ankle joint stiffness and the sex-related difference in the joint stiffness. Localized muscle stiffness of the MG in 16 men and 17 women was assessed at 10° and 20° plantar flexion, neutral anatomical position, 10° and 20° dorsiflexion. Fascicle length and pennation angle of the MG were measured at these joint positions. Passive ankle joint stiffness was determined by the ankle joint angle-torque relationship. Localized MG muscle stiffness was not significantly correlated with passive ankle joint stiffness, and did not show significant sex-related difference, even when considering the muscle architecture. This finding suggest that muscle stiffness of the MG would not be a prominent factor to determine passive ankle joint stiffness and the sex-related difference in the joint stiffness.
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Technology on precision measurement of torque and force
International Nuclear Information System (INIS)
2005-12-01
This book gives a descriptions on force standards system about movement of object, direction and structure. Next, it deals with torque standards, torque measuring instrument and torque wrench with how to use, explanations, unit and test. This book written by Korea Association of standards and testing organizations is for exact measurement and test of force and torque.
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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.
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Computerized Torque Control for Large dc Motors
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.
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Directory of Open Access Journals (Sweden)
Aaron J. Young
2017-06-01
Full Text Available BackgroundDespite a large increase in robotic exoskeleton research, there are few studies that have examined human performance with different control strategies on the same exoskeleton device. Direct comparison studies are needed to determine how users respond to different types of control. The purpose of this study was to compare user performance using a robotic hip exoskeleton with two different controllers: a controller that targeted a biological hip torque profile and a proportional myoelectric controller.MethodsWe tested both control approaches on 10 able-bodied subjects using a pneumatically powered hip exoskeleton. The state machine controller targeted a biological hip torque profile. The myoelectric controller used electromyography (EMG of lower limb muscles to produce a proportional control signal for the hip exoskeleton. Each subject performed two 30-min exoskeleton walking trials (1.0 m/s using each controller and a 10-min trial with the exoskeleton unpowered. During each trial, we measured subjects’ metabolic cost of walking, lower limb EMG profiles, and joint kinematics and kinetics (torques and powers using a force treadmill and motion capture.ResultsCompared to unassisted walking in the exoskeleton, myoelectric control significantly reduced metabolic cost by 13% (p = 0.005 and biological hip torque control reduced metabolic cost by 7% (p = 0.261. Subjects reduced muscle activity relative to the unpowered condition for a greater number of lower limb muscles using myoelectric control compared to the biological hip torque control. More subjects subjectively preferred the myoelectric controller to the biological hip torque control.ConclusionMyoelectric control had more advantages (metabolic cost and muscle activity reduction compared to a controller that targeted a biological torque profile for walking with a robotic hip exoskeleton. However, these results were obtained with a single exoskeleton device with specific
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Young, Aaron J; Gannon, Hannah; Ferris, Daniel P
2017-01-01
Despite a large increase in robotic exoskeleton research, there are few studies that have examined human performance with different control strategies on the same exoskeleton device. Direct comparison studies are needed to determine how users respond to different types of control. The purpose of this study was to compare user performance using a robotic hip exoskeleton with two different controllers: a controller that targeted a biological hip torque profile and a proportional myoelectric controller. We tested both control approaches on 10 able-bodied subjects using a pneumatically powered hip exoskeleton. The state machine controller targeted a biological hip torque profile. The myoelectric controller used electromyography (EMG) of lower limb muscles to produce a proportional control signal for the hip exoskeleton. Each subject performed two 30-min exoskeleton walking trials (1.0 m/s) using each controller and a 10-min trial with the exoskeleton unpowered. During each trial, we measured subjects' metabolic cost of walking, lower limb EMG profiles, and joint kinematics and kinetics (torques and powers) using a force treadmill and motion capture. Compared to unassisted walking in the exoskeleton, myoelectric control significantly reduced metabolic cost by 13% ( p = 0.005) and biological hip torque control reduced metabolic cost by 7% ( p = 0.261). Subjects reduced muscle activity relative to the unpowered condition for a greater number of lower limb muscles using myoelectric control compared to the biological hip torque control. More subjects subjectively preferred the myoelectric controller to the biological hip torque control. Myoelectric control had more advantages (metabolic cost and muscle activity reduction) compared to a controller that targeted a biological torque profile for walking with a robotic hip exoskeleton. However, these results were obtained with a single exoskeleton device with specific control configurations while level walking at a
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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.
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Special-Purpose High-Torque Permanent-Magnet Motors
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.
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Ortega-Peña, Silvestre; Colín-Castro, Claudia; Hernández-Duran, Melissa; López-Jácome, Esaú; Franco-Cendejas, Rafael
2015-01-01
The prosthetic joint infection is the most feared and catastrophic complication for cause severe physical damage to patients and, generates high economic costs. To describe the microbiological characteristics and to determine the resistance pattern in prosthetic joint infections in a reference hospital in Mexico. Patients whose prosthetic devices were withdrawn due to suspicion of septic and aseptic loosening were included. Cultures were performed to identify microorganisms and susceptibility analysis. Of the 111 patients included, 55% were diagnosed with prosthetic joint infection, with the most frequent prosthesis being of the hip (43%). Positive cultures were obtained in 97% of the infected cases, of which 75% were monomicrobial infections. The most frequent bacterial species isolated were: Staphylococcus epidermidis (31%), Enterococcus faecalis (16%), Staphylococcus aureus (13%), and Escherichia coli (8%). The resistance patterns for the Staphylococcus genus were: oxacillin (79%), erythromycin (45%) and ciprofloxacin (37%). Enterococcus faecalis showed a high percentage of resistance to erythromycin and clindamycin (86%), and fluoroquinolones (43%). The large majority (86%) of Escherichia coli were extended spectrum beta-lactamases positive, in addition to having high resistance to fluoroquinolones (86%), trimethoprim/sulfamethoxazole (86%) and gentamicin (72%). The microbiological characteristics found in prosthetic joint infections vary according to the hospitals. In this series, a high proportion of coagulase-negative Staphylococci and Enterococcus spp. were found, as well as a high bacterial resistance. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.
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Heat-driven spin torques in antiferromagnets
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.
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Tailoring spin-orbit torque in diluted magnetic semiconductors
Li, Hang; Wang, Xuhui; Doǧan, Fatih; Manchon, Aurelien
2013-01-01
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.
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Tailoring spin-orbit torque in diluted magnetic semiconductors
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.
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Design of a simple, lightweight, passive-elastic ankle exoskeleton supporting ankle joint stiffness
Kim, Seyoung; Son, Youngsu; Choi, Sangkyu; Ham, Sangyong; Park, Cheolhoon
2015-09-01
In this study, a passive-elastic ankle exoskeleton (PEAX) with a one-way clutch mechanism was developed and then pilot-tested with vertical jumping to determine whether the PEAX is sufficiently lightweight and comfortable to be used in further biomechanical studies. The PEAX was designed to supplement the function of the Achilles tendon and ligaments as they passively support the ankle torque with their inherent stiffness. The main frame of the PEAX consists of upper and lower parts connected to each other by tension springs (N = 3) and lubricated hinge joints. The upper part has an offset angle of 5° with respect to the vertical line when the springs are in their resting state. Each spring has a slack length of 8 cm and connects the upper part to the tailrod of the lower part in the neutral position. The tailrod freely rotates with low friction but has a limited range of motion due to the stop pin working as a one-way clutch. Because of the one-way clutch system, the tension springs store the elastic energy only due to an ankle dorsiflexion when triggered by the stop pin. This clutch mechanism also has the advantage of preventing any inconvenience during ankle plantarflexion because it does not limit the ankle joint motion during the plantarflexion phase. In pilot jumping tests, all of the subjects reported that the PEAX was comfortable for jumping due to its lightweight (approximately 1 kg) and compact (firmly integrated with shoes) design, and subjects were able to nearly reach their maximum vertical jump heights while wearing the PEAX. During the countermovement jump, elastic energy was stored during dorsiflexion by spring extension and released during plantarflexion by spring restoration, indicating that the passive spring torque (i.e., supportive torque) generated by the ankle exoskeleton partially supported the ankle joint torque throughout the process.
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Influence of Closed Stator Slots on Cogging Torque
DEFF Research Database (Denmark)
Ion, Trifu; Leban, Krisztina Monika; Ritchie, Ewen
2013-01-01
Cogging torque results due interaction of magnetic field of magnets and stator slots, and have negative effects on permanent magnet machines such as vibrations, noise, torque ripples and problems during turbine start-up and cut-in. In order to reduce cogging torque this paper presents a study...... of influence of closed stator slots on cogging torque using magnetic slot wedges....
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International Nuclear Information System (INIS)
Liu, C J; Wan, D A
2006-01-01
In order to meet the need of development of integrative flexible joint, this paper presents a higher precision measuring system for angular stiffness test of integrative flexible joint. The main parts of the system include PC, precision motorized goniometric stage, precision motorized rotary stage and high accuracy torque sensor. The measuring and control program is developed on the platform of LabVIEW. The measuring system developed has angular resolution at 0.00032 deg. (about 1'') theoretically in determining the angular displacement of the joint round its equatorial axis and torque accuracy at 0.005 mN · m. The developed program, which presents a friendly GUI, can implement the data acquisition and processing, measuring procedure automatically. In comparison with other measuring devices with similar purposes, the measuring device can improve the measuring efficiency and accuracy distinctly while has advantages of simple configuration, low cost and high stability
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Behery, Omar A; Kester, Benjamin S; Williams, Jarrett; Bosco, Joseph A; Slover, James D; Iorio, Richard; Schwarzkopf, Ran
2017-04-01
Alternative payment models aim to improve quality and decrease costs associated with total joint replacement. Postoperative readmissions within 90 days are of interest to clinicians and administrators as there is no additional reimbursement beyond the episode bundled payment target price. The aim of this study is to improve the understanding of the patterns of readmission which would better guide perioperative patient management affecting readmissions. We hypothesize that readmissions have different timing, location, and patient health profile patterns based on whether the readmission is related to a medical or surgical diagnosis. A retrospective cohort of 80 readmissions out of 1412 total joint replacement patients reimbursed through a bundled payment plan was analyzed. Patients were grouped by readmission diagnosis (surgical or medical) and the main variables analyzed were time to readmission, location of readmission, and baseline Perioperative Orthopaedic Surgical Home and American Society of Anesthesiologists scores capturing pre-existing state of health. Nonparametric tests and multivariable regressions were used to test associations. Surgical readmissions occurred earlier than medical readmissions (mean 18 vs 33 days, P = .011), and were more likely to occur at the hospital where the surgery was performed (P = .035). Perioperative Orthopaedic Surgical Home and American Society of Anesthesiologists scores did not predict medical vs surgical readmissions (P = .466 and .879) after adjusting for confounding variables. Readmissions appear to follow different patterns depending on whether they are surgical or medical. Surgical readmissions occur earlier than medical readmissions, and more often at the hospital where the surgery was performed. The results of this study suggest that these 2 types of readmissions have different patterns with different implications toward perioperative care and follow-up after total joint replacement. Copyright © 2016 Elsevier Inc
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A mechanism to compensate undesired stiffness in joints of prosthetic hands
Smit, G.; Plettenbrug, D.H.; Van der Helm, F.C.T.
2014-01-01
Background: Cosmetic gloves that cover a prosthetic hand have a parasitic positive stiffness that counteracts the flexion of a finger joint. Objectives: Reducing the required input torque to move a finger of a prosthetic hand by compensating the parasitic stiffness of the cosmetic glove. Study
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Herda, Trent J; Zuniga, Jorge M; Ryan, Eric D; Camic, Clayton L; Bergstrom, Haley C; Smith, Doug B; Weir, Joseph P; Cramer, Joel T; Housh, Terry J
2015-06-01
This study examined the effects of electromyographic (EMG) recording methods and innervation zone (IZ) on the mean power frequency (MPF)-torque relationships. Nine subjects performed isometric ramp muscle actions of the leg extensors from 5% to 100% of maximal voluntary contraction with an eight channel linear electrode array over the IZ of the vastus lateralis. The slopes were calculated from the log-transformed monopolar and bipolar EMG MPF-torque relationships for each channel and subject and 95% confidence intervals (CI) were constructed around the slopes for each relationship and the composite of the slopes. Twenty-two to 55% of the subjects exhibited 95% CIs that did not include a slope of zero for the monopolar EMG MPF-torque relationships while 25-75% of the subjects exhibited 95% CIs that did not include a slope of zero for the bipolar EMG MPF-torque relationships. The composite of the slopes from the EMG MPF-torque relationships were not significantly different from zero for any method or channel, however, the method and IZ location slightly influenced the number of significant slopes on a subject-by-subject basis. The log-transform model indicated that EMG MPF-torque patterns were nonlinear regardless of recording method or distance from the IZ. Copyright © 2015 Elsevier Ltd. All rights reserved.
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de Rugy, Aymar; Riek, Stephan; Carson, Richard G
2006-01-01
The authors tested for predominant patterns of coordination in the combination of rhythmic flexion-extension (FE) and supination- (SP) at the elbow-joint complex. Participants (N=10) spontaneously established in-phase (supination synchronized with flexion) and antiphase (pronation synchronized with flexion) patterns. In addition, the authors used a motorized robot arm to generate involuntary SP movements with different phase relations with respect to voluntary FE. The involuntarily induced in-phase pattern was accentuated and was more consistent than other patterns. The result provides evidence that the predominance of the in-phase pattern originates in the influence of neuromuscular-skeletal constraints rather than in a preference dictated by perceptual-cognitive factors implicated in voluntary control. Neuromuscular-skeletal constraints involved in the predominance of the in-phase and the antiphase patterns are discussed.
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Directory of Open Access Journals (Sweden)
Dingguo Zhang
2017-12-01
Full Text Available Functional electrical stimulation (FES and robotic exoskeletons are two important technologies widely used for physical rehabilitation of paraplegic patients. We developed a hybrid rehabilitation system (FEXO Knee that combined FES and an exoskeleton for swinging movement control of human knee joints. This study proposed a novel cooperative control strategy, which could realize arbitrary distribution of torque generated by FES and exoskeleton, and guarantee harmonic movements. The cooperative control adopted feedfoward control for FES and feedback control for exoskeleton. A parameter regulator was designed to update key parameters in real time to coordinate FES controller and exoskeleton controller. Two muscle groups (quadriceps and hamstrings were stimulated to generate active torque for knee joint in synchronization with torque compensation from exoskeleton. The knee joint angle and the interactive torque between exoskeleton and shank were used as feedback signals for the control system. Central pattern generator (CPG was adopted that acted as a phase predictor to deal with phase confliction of motor patterns, and realized synchronization between the two different bodies (shank and exoskeleton. Experimental evaluation of the hybrid FES-exoskeleton system was conducted on five healthy subjects and four paraplegic patients. Experimental results and statistical analysis showed good control performance of the cooperative control on torque distribution, trajectory tracking, and phase synchronization.
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Zhang, Dingguo; Ren, Yong; Gui, Kai; Jia, Jie; Xu, Wendong
2017-01-01
Functional electrical stimulation (FES) and robotic exoskeletons are two important technologies widely used for physical rehabilitation of paraplegic patients. We developed a hybrid rehabilitation system (FEXO Knee) that combined FES and an exoskeleton for swinging movement control of human knee joints. This study proposed a novel cooperative control strategy, which could realize arbitrary distribution of torque generated by FES and exoskeleton, and guarantee harmonic movements. The cooperative control adopted feedfoward control for FES and feedback control for exoskeleton. A parameter regulator was designed to update key parameters in real time to coordinate FES controller and exoskeleton controller. Two muscle groups (quadriceps and hamstrings) were stimulated to generate active torque for knee joint in synchronization with torque compensation from exoskeleton. The knee joint angle and the interactive torque between exoskeleton and shank were used as feedback signals for the control system. Central pattern generator (CPG) was adopted that acted as a phase predictor to deal with phase confliction of motor patterns, and realized synchronization between the two different bodies (shank and exoskeleton). Experimental evaluation of the hybrid FES-exoskeleton system was conducted on five healthy subjects and four paraplegic patients. Experimental results and statistical analysis showed good control performance of the cooperative control on torque distribution, trajectory tracking, and phase synchronization.
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Accuracy of mechanical torque-limiting devices for dental implants.
L'Homme-Langlois, Emilie; Yilmaz, Burak; Chien, Hua-Hong; McGlumphy, Edwin
2015-10-01
A common complication in implant dentistry is unintentional implant screw loosening. The critical factor in the prevention of screw loosening is the delivery of the appropriate target torque value. Mechanical torque-limiting devices (MTLDs) are the most frequently recommended devices by the implant manufacturers to deliver the target torque value to the screw. Two types of MTLDs are available: friction-style and spring-style. Limited information is available regarding the influence of device type on the accuracy of MTLDs. The purpose of this study was to determine and compare the accuracy of spring-style and friction-style MTLDs. Five MTLDs from 6 different dental implant manufacturers (Astra Tech/Dentsply, Zimmer Dental, Biohorizons, Biomet 3i, Straumann [ITI], and Nobel Biocare) (n=5 per manufacturer) were selected to determine their accuracy in delivering target torque values preset by their manufacturers. All torque-limiting devices were new and there were 3 manufacturers for the friction-style and 3 manufacturers for the spring-style. The procedure of target torque measurement was performed 10 times for each device and a digital torque gauge (Chatillon Model DFS2-R-ND; Ametek) was used to record the measurements. Statistical analysis used nonparametric tests to determine the accuracy of the MTLDs in delivering target torque values and Bonferroni post hoc tests were used to assess pairwise comparisons. Median absolute difference between delivered torque values and target torque values of friction-style and spring-style MTLDs were not significantly different (P>.05). Accuracy of Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly different than Biohorizons torque-limiting devices (Ptorque value. Astra Tech and Zimmer Dental friction-style torque-limiting devices were significantly more accurate than Biohorizons (C) torque-limiting devices (Ptorque-limiting devices fell within ±10% of the target torque value preset by the
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Integral torque balance in tokamaks
International Nuclear Information System (INIS)
Pustovitov, V.D.
2011-01-01
The study is aimed at clarifying the balance between the sinks and sources in the problem of intrinsic plasma rotation in tokamaks reviewed recently by deGrassie (2009 Plasma Phys. Control. Fusion 51 124047). The integral torque on the toroidal plasma is calculated analytically using the most general magnetohydrodynamic (MHD) plasma model taking account of plasma anisotropy and viscosity. The contributions due to several mechanisms are separated and compared. It is shown that some of them, though, possibly, important in establishing the rotation velocity profile in the plasma, may give small input into the integral torque, but an important contribution can come from the magnetic field breaking the axial symmetry of the configuration. In tokamaks, this can be the error field, the toroidal field ripple or the magnetic perturbation created by the correction coils in the dedicated experiments. The estimates for the error-field-induced electromagnetic torque show that the amplitude of this torque is comparable to the typical values of torques introduced into the plasma by neutral beam injection. The obtained relations allow us to quantify the effect that can be produced by the existing correction coils in tokamaks on the plasma rotation, which can be used in experiments to study the origin and physics of intrinsic rotation in tokamaks. Several problems are proposed for theoretical studies and experimental tests.
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Gao, Fan; Carlton, William; Kapp, Susan
2011-06-01
Articulated or hinged ankle-foot orthosis (AFO) allow more range of motion. However, quantitative investigation on articulated AFO is still sparse. The objective of the study was to quantitatively investigate effects of alignment and joint types on mechanical properties of the thermoplastic articulated AFO. Tamarack dorsiflexion assist flexure joints with three durometers (75, 85 and 95) and free motion joint were tested. The AFO joint was aligned with the center of the motor shaft (surrogate ankle joint), 10 mm superior, inferior, anterior and posterior with respect to the motor shaft center. The AFO was passively moved from 20° plantar flexion to 15° dorsiflexion at a speed of 10°/s using a motorized device. Mechanical properties including index of hysteresis, passive resistance torque and quasi-static stiffness (at neutral, 5°, 10° and 15° in plantar flexion) were quantified. Significant effects of joint types and joint alignment on the mechanical properties of an articulated thermoplastic AFO were revealed. Specifically, center alignment showed minimum resistance and stiffness while anterior and posterior alignment showed significantly higher resistance and stiffness. The dorsiflexion assist torques at neutral position ranged from 0.69 ± 0.09 to 1.88 ± 0.10 Nm. Anterior and posterior alignment should be avoided as much as possible. The current study suggested that anterior and posterior alignment be avoided as much as possible in clinical practice due to potential skin irritation and increase in stress around the ankle joint.
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TORQUE MEASUREMENT IN WORM AGLOMERATION MACHINE
Directory of Open Access Journals (Sweden)
Marian DUDZIAK
2014-03-01
Full Text Available The paper presents the operating characteristics of the worm agglomeration machine. The paper indicates the need for continuous monitoring of the value of the torque due to the efficiency of the machine. An original structure of torque meter which is built in the standard drive system of briquetting machine was presented. A number of benefits arising from the application of the proposed solution were presented. Exemplary measurement results obtained by means of this torque meter were presented.
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Sugiura, Yoshito; Hatanaka, Yasuhiko; Arai, Tomoaki; Sakurai, Hiroaki; Kanada, Yoshikiyo
2016-04-01
We aimed to investigate whether a linear regression formula based on the relationship between joint torque and angular velocity measured using a high-speed video camera and image measurement software is effective for estimating 1 repetition maximum (1RM) and isometric peak torque in knee extension. Subjects comprised 20 healthy men (mean ± SD; age, 27.4 ± 4.9 years; height, 170.3 ± 4.4 cm; and body weight, 66.1 ± 10.9 kg). The exercise load ranged from 40% to 150% 1RM. Peak angular velocity (PAV) and peak torque were used to estimate 1RM and isometric peak torque. To elucidate the relationship between force and velocity in knee extension, the relationship between the relative proportion of 1RM (% 1RM) and PAV was examined using simple regression analysis. The concordance rate between the estimated value and actual measurement of 1RM and isometric peak torque was examined using intraclass correlation coefficients (ICCs). Reliability of the regression line of PAV and % 1RM was 0.95. The concordance rate between the actual measurement and estimated value of 1RM resulted in an ICC(2,1) of 0.93 and that of isometric peak torque had an ICC(2,1) of 0.87 and 0.86 for 6 and 3 levels of load, respectively. Our method for estimating 1RM was effective for decreasing the measurement time and reducing patients' burden. Additionally, isometric peak torque can be estimated using 3 levels of load, as we obtained the same results as those reported previously. We plan to expand the range of subjects and examine the generalizability of our results.
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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
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Temperature dependence of spin-orbit torques in Cu-Au alloys
Wen, Yan; Wu, Jun; Li, Peng; Zhang, Qiang; Zhao, Yuelei; Manchon, Aurelien; Xiao, John Q.; Zhang, Xixiang
2017-01-01
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.
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Temperature dependence of spin-orbit torques in Cu-Au alloys
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.
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Oliver, Michele; Rogers, Robert; Rickards, Jeremy; Tingley, Maureen; Biden, Edmund
2006-02-22
The purpose of this work was to quantify the effects of joystick stiffness and movement speed on the dynamic torque characteristics of hydraulic-actuation joystick controls, as found in off-road vehicles, as one of the initial steps towards the development of a joystick design protocol. Using a previously developed mathematical model in which a hydraulic-actuation joystick is assumed to rotate about two axes where the rotation origin is a universal joint, the dynamic torque characteristics incurred by an operator were predicted. Utilizing a laboratory mock-up of an excavator cab environment, three actuation torque characteristics (peak torque, angular impulse and deceleration at the hard endpoint) were quantified for nine unskilled joystick operators during the use of a commonly used North American hydraulic-actuation joystick. The six different experimental conditions included combinations of three joystick stiffnesses and two movement speeds. The highest instantaneous input torque over the course of the joystick movement (not including the hard endpoint) was evaluated using the peak torque value. Angular impulse provided an indication of the sustained exposure to force. The third indicator, deceleration at the hard endpoint, was included to provide a description of impact loading on the hand as the joystick came to a sudden stop. The most important result of this work is that the dynamic torque characteristics incurred during hydraulic-actuation joystick use are substantial. While the peak torque values were not very different between the fast and slow motion conditions, the high decelerations even for slow movements observed at maximum excursion of the joystick indicate that the dynamics do matter. On the basis of deceleration at the hard endpoint and peak torque, the joystick movements that require the highest values for a combination of torque variables are the side-to-side ones. This suggests that less stiff balance and return springs should be considered for
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Tapered joint design for power transmission of MW-grade wind turbine
Energy Technology Data Exchange (ETDEWEB)
Kang, Jong Hun; Bae, Jun Woo; Oh, Han Yong [Dept. of Mechatronics, Jungwon University, Geosan (Korea, Republic of); Kwon, Yong Chul [Kyeongnam Technopark, Changwon (Korea, Republic of)
2015-11-15
This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.
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Spin-torque generation in topological insulator based heterostructures
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.
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Current-induced torques and interfacial spin-orbit coupling
Haney, Paul M.; Lee, Hyun-Woo; Lee, Kyung-Jin; Manchon, Aurelien; Stiles, M. D.
2013-01-01
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.
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Detecting Casimir torque with an optically levitated nanorod
Xu, Zhujing; Li, Tongcang
2017-09-01
The linear momentum and angular momentum of virtual photons of quantum vacuum fluctuations can induce the Casimir force and the Casimir torque, respectively. While the Casimir force has been measured extensively, the Casimir torque has not been observed experimentally though it was predicted over 40 years ago. Here we propose to detect the Casimir torque with an optically levitated nanorod near a birefringent plate in vacuum. The axis of the nanorod tends to align with the polarization direction of the linearly polarized optical tweezer. When its axis is not parallel or perpendicular to the optical axis of the birefringent crystal, it will experience a Casimir torque that shifts its orientation slightly. We calculate the Casimir torque and Casimir force acting on a levitated nanorod near a birefringent crystal. We also investigate the effects of thermal noise and photon recoils on the torque and force detection. We prove that a levitated nanorod in vacuum will be capable of detecting the Casimir torque under realistic conditions, and will be an important tool in precision measurements.
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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°.
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Current-induced torques and interfacial spin-orbit coupling
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.
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Manchikanti, Laxmaiah; Hansen, Hans; Pampati, Vidyasagar; Falco, Frank J E
2013-01-01
The high prevalence of persistent low back pain and growing number of diagnostic and therapeutic modalities employed to manage chronic low back pain and the subsequent impact on society and the economy continue to hold sway over health care policy. Among the multiple causes responsible for chronic low back pain, the contributions of the sacroiliac joint have been a subject of debate albeit a paucity of research. At present, there are no definitive conservative, interventional or surgical management options for managing sacroiliac joint pain. It has been shown that the increases were highest for facet joint interventions and sacroiliac joint blocks with an increase of 310% per 100,000 Medicare beneficiaries from 2000 to 2011. There has not been a systematic assessment of the utilization and growth patterns of sacroiliac joint injections. Analysis of the growth patterns of sacroiliac joint injections in Medicare beneficiaries from 2000 to 2011. To evaluate the utilization and growth patterns of sacroiliac joint injections. This assessment was performed utilizing Centers for Medicare and Medicaid Services (CMS) Physician/Supplier Procedure Summary (PSPS) Master data from 2000 to 2011. The findings of this assessment in Medicare beneficiaries from 2000 to 2011 showed a 331% increase per 100,000 Medicare beneficiaries with an annual increase of 14.2%, compared to an increase in the Medicare population of 23% or annual increase of 1.9%. The number of procedures increased from 49,554 in 2000 to 252,654 in 2011, or a rate of 125 to 539 per 100,000 Medicare beneficiaries. Among the various specialists performing sacroiliac joint injections, physicians specializing in physical medicine and rehabilitation have shown the most increase, followed by neurology with 1,568% and 698%, even though many physicians from both specialties have been enrolling in interventional pain management and pain management. Even though the numbers were small for nonphysician providers including
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Modulation of shoulder muscle and joint function using a powered upper-limb exoskeleton.
Wu, Wen; Fong, Justin; Crocher, Vincent; Lee, Peter V S; Oetomo, Denny; Tan, Ying; Ackland, David C
2018-04-27
Robotic-assistive exoskeletons can enable frequent repetitive movements without the presence of a full-time therapist; however, human-machine interaction and the capacity of powered exoskeletons to attenuate shoulder muscle and joint loading is poorly understood. This study aimed to quantify shoulder muscle and joint force during assisted activities of daily living using a powered robotic upper limb exoskeleton (ArmeoPower, Hocoma). Six healthy male subjects performed abduction, flexion, horizontal flexion, reaching and nose touching activities. These tasks were repeated under two conditions: (i) the exoskeleton compensating only for its own weight, and (ii) the exoskeleton providing full upper limb gravity compensation (i.e., weightlessness). Muscle EMG, joint kinematics and joint torques were simultaneously recorded, and shoulder muscle and joint forces calculated using personalized musculoskeletal models of each subject's upper limb. The exoskeleton reduced peak joint torques, muscle forces and joint loading by up to 74.8% (0.113 Nm/kg), 88.8% (5.8%BW) and 68.4% (75.6%BW), respectively, with the degree of load attenuation strongly task dependent. The peak compressive, anterior and superior glenohumeral joint force during assisted nose touching was 36.4% (24.6%BW), 72.4% (13.1%BW) and 85.0% (17.2%BW) lower than that during unassisted nose touching, respectively. The present study showed that upper limb weight compensation using an assistive exoskeleton may increase glenohumeral joint stability, since deltoid muscle force, which is the primary contributor to superior glenohumeral joint shear, is attenuated; however, prominent exoskeleton interaction moments are required to position and control the upper limb in space, even under full gravity compensation conditions. The modeling framework and results may be useful in planning targeted upper limb robotic rehabilitation tasks. Copyright © 2018 Elsevier Ltd. All rights reserved.
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Estimating Torque Imparted on Spacecraft Using Telemetry
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.
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Beil, Jonas; Marquardt, Charlotte; Asfour, Tamim
2017-07-01
Kinematic compatibility is of paramount importance in wearable robotic and exoskeleton design. Misalignments between exoskeletons and anatomical joints of the human body result in interaction forces which make wearing the exoskeleton uncomfortable and even dangerous for the human. In this paper we present a kinematically compatible design of an exoskeleton hip to reduce kinematic incompatibilities, so called macro- and micro-misalignments, between the human's and exoskeleton's joint axes, which are caused by inter-subject variability and articulation. The resulting design consists of five revolute, three prismatic and one ball joint. Design parameters such as range of motion and joint velocities are calculated based on the analysis of human motion data acquired by motion capture systems. We show that the resulting design is capable of self-aligning to the human hip joint in all three anatomical planes during operation and can be adapted along the dorsoventral and mediolateral axis prior to operation. Calculation of the forward kinematics and FEM-simulation considering kinematic and musculoskeletal constraints proved sufficient mobility and stiffness of the system regarding the range of motion, angular velocity and torque admissibility needed to provide 50 % assistance for an 80 kg person.
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Robust spin transfer torque in antiferromagnetic tunnel junctions
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.
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Directory of Open Access Journals (Sweden)
Xin Wang
2018-03-01
Full Text Available The contradiction between self-weight and load capacity of a power-assisted upper-limb exoskeleton for material hanging is unresolved. In this paper, a non-anthropomorphic 3-degree of freedom (DOF upper-limb exoskeleton with an internally rotated elbow joint is proposed based on an anthropomorphic 5-DOF upper-limb exoskeleton for power-assisted activity. The proposed 3-DOF upper-limb exoskeleton contains a 2-DOF shoulder joint and a 1-DOF internally rotated elbow joint. The structural parameters of the 3-DOF upper-limb exoskeleton were determined, and the differences and singularities of the two exoskeletons were analyzed. The workspace, the joint torques and the power consumption of two exoskeletons were analyzed by kinematics and dynamics, and an exoskeleton prototype experiment was performed. The results showed that, compared with a typical anthropomorphic upper-limb exoskeleton, the non-anthropomorphic 3-DOF upper-limb exoskeleton had the same actual workspace; eliminated singularities within the workspace; improved the elbow joint force situation; and the maximum elbow joint torque, elbow external-flexion/internal-extension and shoulder flexion/extension power consumption were significantly reduced. The proposed non-anthropomorphic 3-DOF upper-limb exoskeleton can be applied to a power-assisted upper-limb exoskeleton in industrial settings.
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PASTERNAK-JÚNIOR, Braulio; de SOUSA NETO, Manoel Damião; DIONÍSIO, Valdeci Carlos; PÉCORA, Jesus Djalma; SILVA, Ricardo Gariba
2012-01-01
Objective This study assessed the muscular activity during root canal preparation through kinematics, kinetics, and electromyography (EMG). Material and Methods The operators prepared one canal with RaCe rotary instruments and another with Flexo-files. The kinematics of the major joints was reconstructed using an optoelectronic system and electromyographic responses of the flexor carpi radialis, extensor carpi radialis, brachioradialis, biceps brachii, triceps brachii, middle deltoid, and upper trapezius were recorded. The joint torques of the shoulder, elbow and wrist were calculated using inverse dynamics. In the kinematic analysis, angular movements of the wrist and elbow were classified as low risk factors for work-related musculoskeletal disorders. With respect to the shoulder, the classification was medium-risk. Results There was no significant difference revealed by the kinetic reports. The EMG results showed that for the middle deltoid and upper trapezius the rotary instrumentation elicited higher values. The flexor carpi radialis and extensor carpi radialis, as well as the brachioradialis showed a higher value with the manual method. Conclusion The muscular recruitment for accomplishment of articular movements for root canal preparation with either the rotary or manual techniques is distinct. Nevertheless, the rotary instrument presented less difficulty in the generation of the joint torque in each articulation, thus, presenting a greater uniformity of joint torques. PMID:22437679
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sEMG-based joint force control for an upper-limb power-assist exoskeleton robot.
Li, Zhijun; Wang, Baocheng; Sun, Fuchun; Yang, Chenguang; Xie, Qing; Zhang, Weidong
2014-05-01
This paper investigates two surface electromyogram (sEMG)-based control strategies developed for a power-assist exoskeleton arm. Different from most of the existing position control approaches, this paper develops force control methods to make the exoskeleton robot behave like humans in order to provide better assistance. The exoskeleton robot is directly attached to a user's body and activated by the sEMG signals of the user's muscles, which reflect the user's motion intention. In the first proposed control method, the forces of agonist and antagonist muscles pair are estimated, and their difference is used to produce the torque of the corresponding joints. In the second method, linear discriminant analysis-based classifiers are introduced as the indicator of the motion type of the joints. Then, the classifier's outputs together with the estimated force of corresponding active muscle determine the torque control signals. Different from the conventional approaches, one classifier is assigned to each joint, which decreases the training time and largely simplifies the recognition process. Finally, the extensive experiments are conducted to illustrate the effectiveness of the proposed approaches.
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Torque control for electric motors
Bernard, C. A.
1980-01-01
Method for adjusting electric-motor torque output to accomodate various loads utilizes phase-lock loop to control relay connected to starting circuit. As load is imposed, motor slows down, and phase lock is lost. Phase-lock signal triggers relay to power starting coil and generate additional torque. Once phase lock is recoverd, relay restores starting circuit to its normal operating mode.
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Infrared target recognition based on improved joint local ternary pattern
Sun, Junding; Wu, Xiaosheng
2016-05-01
This paper presents a simple, efficient, yet robust approach, named joint orthogonal combination of local ternary pattern, for automatic forward-looking infrared target recognition. It gives more advantages to describe the macroscopic textures and microscopic textures by fusing variety of scales than the traditional LBP-based methods. In addition, it can effectively reduce the feature dimensionality. Further, the rotation invariant and uniform scheme, the robust LTP, and soft concave-convex partition are introduced to enhance its discriminative power. Experimental results demonstrate that the proposed method can achieve competitive results compared with the state-of-the-art methods.
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Experimental analysis of mechanical joints strength by means of energy dissipation
Wolf, Alexander; Lafarge, Remi; Kühn, Tino; Brosius, Alexander
2018-05-01
Designing complex structures with the demand for weight reduction leads directly to a multi-material concept. This mixture has to be joined securely and welding, mechanical joining and the usage of adhesives are commonly used for that purpose. Sometimes also a mix of at least two materials is useful to combine the individual advantages. The challenge is the non-destructive testing of these connections because destructive testing requires a lot of preparation and expensive testing equipment. The authors show a testing method by measuring and analysing the energy dissipation in mechanical joints. Known methods are radiography, thermography and ultrasound testing. Unfortunately, the usage of these methods is difficult and often not usable in fibre-reinforced-plastics. The presented approach measures the propagation of the elastic strain wave through the joint. A defined impact strain is detected with by strain-gauges whereby the transmitter is located on one side of the joint and the receiver on the other, respectively. Because of different mechanisms, energy dissipates by passing the joint areas. Main reasons are damping caused by friction and material specific damping. Insufficient performed joints lead to an effect especially in the friction damping. By the measurement of the different strains and the resulting energy loss a statement to the connection quality is given. The possible defect during the execution of the joint can be identified by the energy loss and strain vs. time curve. After the description of the method, the authors present the results of energy dissipation measurements at a bolted assembly with different locking torques. By the adjustable tightening torques for the screw connections easily a variation of the contact pressure can be applied and analysed afterwards. The outlook will give a statement for the usability for other mechanical joints and fibre-reinforced-plastics.
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Torque Measurement at the Single Molecule Level
Forth, Scott; Sheinin, Maxim Y.; Inman, James; Wang, Michelle D.
2017-01-01
Methods for exerting and measuring forces on single molecules have revolutionized the study of the physics of biology. However, it is often the case that biological processes involve rotation or torque generation, and these parameters have been more difficult to access experimentally. Recent advances in the single molecule field have led to the development of techniques which add the capability of torque measurement. By combining force, displacement, torque, and rotational data, a more comprehensive description of the mechanics of a biomolecule can be achieved. In this review, we highlight a number of biological processes for which torque plays a key mechanical role. We describe the various techniques that have been developed to directly probe the torque experienced by a single molecule, and detail a variety of measurements made to date using these new technologies. We conclude by discussing a number of open questions and propose systems of study which would be well suited for analysis with torsional measurement techniques. PMID:23541162
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Angular dependence of spin-orbit spin-transfer torques
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.
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Angular dependence of spin-orbit spin-transfer torques
Lee, Ki-Seung; Go, Dongwook; Manchon, Aurelien; Haney, Paul M.; Stiles, M. D.; Lee, Hyun-Woo; Lee, Kyung-Jin
2015-01-01
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.
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Directory of Open Access Journals (Sweden)
Renato Sussumu Nishioka
2010-06-01
Full Text Available OBJECTIVE: Using strain gauge (SG analysis, the aim of this in vitro study was quantify the strain development during the fixation of three-unit screw implant-supported fixed partial dentures, varying the types of implant-abutment joints and the type of prosthetic coping. The hypotheses were that the type of hexagonal connection would generate different microstrains and the type of copings would produce similar microstrains after prosthetic screws had been tightened onto microunit abutments. MATERIALS AND METHODS: Three dental implants with external (EH and internal (IH hexagonal configurations were inserted into two polyurethane blocks. Microunit abutments were screwed onto their respective implant groups, applying a torque of 20 Ncm. Machined Co-Cr copings (M and plastic prosthetic copings (P were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in Co-Cr alloy (n=5, forming four groups: G1 EH/M; G2 EH/P; G3 IH/M and G4 IH/P. Four SGs were bonded onto the surface of the block tangentially to the implants, SG 1 mesially to implant 1, SG 2 and SG 3 mesially and distally to implant 2, respectively, and SG 4 distally to implant 3. The superstructure's occlusal screws were tightened onto microunit abutments with 10 Ncm torque using a manual torque driver. The magnitude of microstrain on each SG was recorded in units of microstrain (µε. The data were analyzed statistically by ANOVA and Tukey's test (p0.05. The hypotheses were partially accepted. CONCLUSIONS: It was concluded that the type of hexagonal connection and coping presented similar mechanical behavior under tightening conditions.
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Elbow joint stability in relation to forced external rotation
DEFF Research Database (Denmark)
Deutch, S.R.; Jensen, S.L.; Olsen, B.S.
2003-01-01
The objective of this study was to evaluate the osseous constraint related to forced forearm external rotation as the initial stage in a posterior elbow dislocation. Six joint specimens without soft tissues were examined in a joint analysis system developed for simulation of dislocation. The osse......The objective of this study was to evaluate the osseous constraint related to forced forearm external rotation as the initial stage in a posterior elbow dislocation. Six joint specimens without soft tissues were examined in a joint analysis system developed for simulation of dislocation...... external forearm rotation until the point of maximal torque decreased from a maximum in full extension to a minimum at 30 degrees of elbow flexion (P =.03). The elbow in a slightly flexed position, varus stress, and forearm external rotation trauma might be the important biomechanical factors...
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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.
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Muscle and reflex changes with varying joint angle in hemiparetic stroke
Directory of Open Access Journals (Sweden)
Alibiglou Laila
2008-02-01
Full Text Available Abstract Background Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint. Methods Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM. Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls. Results Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position. Conclusion In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated. Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects
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40 CFR 91.306 - Dynamometer torque cell calibration.
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Provisions § 91.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a force through a distance into a torque must be used in a horizontal position for horizontal shaft...
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40 CFR 90.306 - Dynamometer torque cell calibration.
2010-07-01
... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Dynamometer torque cell calibration... Emission Test Equipment Provisions § 90.306 Dynamometer torque cell calibration. (a)(1) Any lever arm used to convert a weight or a force through a distance into a torque must be used in a horizontal position...
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Dynamic analysis of cross shaft type universal joint with clearance
International Nuclear Information System (INIS)
Lu, Jian Wei; Wang, Gong Cheng; Chen, Hao; Vakakis, Alexander F.; Bergman, Lawrence A.
2013-01-01
Cross shaft type universal joint is widely used in ground vehicles to transfer torque between two intersecting axes, and its transmission feature can make a great contribution to NVH performance of the vehicle. We looked at the assembling clearance at cross shaft neck, and presented a dynamic model of cross shaft type universal joint with clearance at cross shaft neck. Two-state model is applied to describe the contact force between the cross shaft and driving joint fork based on Hertz theorem, and lumped mass method is applied to build up the dynamic model of the universal joint. Based on this model, numerical analysis is carried out to discuss the transmission feature of the universal joint with clearance at cross shaft neck, and the influence of clearance on the dynamic behavior of the system is evaluated with numerical results based on time history, power spectrum, and phase portrait. The method and conclusions presented are helpful to improvement of the transmission feature of cross shaft type universal joint.
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A Common Force-Sharing Pattern in Joint Action That Consists of Four People.
Masumoto, Junya; Inui, Nobuyuki
2017-12-20
The authors examined the force-sharing patterns in a joint action performed by a group of two, three, or four people compared with a solo action. In the joint actions, 28 participants produced periodic isometric forces such that the sum of forces they produced cycled between 5% and 10% maximum voluntary contraction with the right hand at 1 Hz. In both the three- and four-person tasks, the correlation between forces produced by two of the three or four participants was negative, and the remaining one or two participants produced intermediate forces. The errors of force and interval and force variabilities were smaller in four- and three-people groups than individuals. Four- and three-people groups thus performed better than individuals.
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Analysis of a non-contact magnetoelastic torque transducer
International Nuclear Information System (INIS)
Andreescu, R.; Spellman, B.; Furlani, E.P.
2008-01-01
Results are presented for the performance of a magnetoelastic torque transducer that converts a torque-induced strain in a non-magnetic shaft into changes in a measurable magnetic field. The magnetic field is generated by a thin magnetostrictive layer that is coated onto the circumference of the shaft. The layer is magnetized and has an initial residual strain. The magnetization within the layer rotates in response to changes in the strain which occur when the shaft is torqued. The magnetic field produced by the layer changes with the magnetization and this can be sensed by a magnetometer to monitor the torque on the shaft. In this paper, a phenomenological theory is developed for predicting the performance of the transducer. The theory can be used to predict the magnetic field distribution of the transducer as a function of the physical properties of the magnetic coating, its residual strain, and the applied torque. It enables rapid parametric analysis of transducer performance, which is useful for the development and optimization of novel non-contact torque sensors
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Directory of Open Access Journals (Sweden)
Wei Ye
2018-05-01
Full Text Available In this paper, by evaluating the extreme value of the qth-power current, a torque sharing function (TSF family for reducing the torque ripples in the switched reluctance motor (SRM is proposed. The optimization criteria of the TSF has two secondary objectives, including the maximization of the torque-speed range and the minimization of copper loss. The evaluation indices in terms of the peak phase current, the rms (root mean square phase current, and the torque ripple factor are compared between the proposed TSF family and four conventional TSFs including linear, sinusoidal, exponential, and cubic TSFs. An optimization objective function that combines the maximum absolute value of the rate-of-change of the flux linkage (MAV-RCFL and the qth-power of current is proposed and a weighting factor is used to balance the influence of the two optimization objectives. An optimal TSF can be easily obtained by solving the optimization problem from the TSF family. The proposed TSF is validated by using simulations and experiments with a three-phase 6/4 SRM with 7.5 kW, 3000 rpm, and 270 V DC-link voltage. The dynamic simulation model is implemented in Matlab/Simulink. The results demonstrate the validity and superiority of the proposed control method; the optimal TSF provides better torque-speed performance, and a better reduction in copper loss and torque ripples at high speed, as compared to conventional TSFs.
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Propulsive efficiency of frog swimming with different feet and swimming patterns
Directory of Open Access Journals (Sweden)
Fan Jizhuang
2017-04-01
Full Text Available Aquatic and terrestrial animals have different swimming performances and mechanical efficiencies based on their different swimming methods. To explore propulsion in swimming frogs, this study calculated mechanical efficiencies based on data describing aquatic and terrestrial webbed-foot shapes and swimming patterns. First, a simplified frog model and dynamic equation were established, and hydrodynamic forces on the foot were computed according to computational fluid dynamic calculations. Then, a two-link mechanism was used to stand in for the diverse and complicated hind legs found in different frog species, in order to simplify the input work calculation. Joint torques were derived based on the virtual work principle to compute the efficiency of foot propulsion. Finally, two feet and swimming patterns were combined to compute propulsive efficiency. The aquatic frog demonstrated a propulsive efficiency (43.11% between those of drag-based and lift-based propulsions, while the terrestrial frog efficiency (29.58% fell within the range of drag-based propulsion. The results illustrate the main factor of swimming patterns for swimming performance and efficiency.
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Multi-digit maximum voluntary torque production on a circular object
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
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Spin-Stabilized Spacecrafts: Analytical Attitude Propagation Using Magnetic Torques
Directory of Open Access Journals (Sweden)
Roberta Veloso Garcia
2009-01-01
Full Text Available An analytical approach for spin-stabilized satellites attitude propagation is presented, considering the influence of the residual magnetic torque and eddy currents torque. It is assumed two approaches to examine the influence of external torques acting during the motion of the satellite, with the Earth's magnetic field described by the quadripole model. In the first approach is included only the residual magnetic torque in the motion equations, with the satellites in circular or elliptical orbit. In the second approach only the eddy currents torque is analyzed, with the satellite in circular orbit. The inclusion of these torques on the dynamic equations of spin stabilized satellites yields the conditions to derive an analytical solution. The solutions show that residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spacecraft's spin axis and the eddy currents torque causes an exponential decay of the angular velocity magnitude. Numerical simulations performed with data of the Brazilian Satellites (SCD1 and SCD2 show the period that analytical solution can be used to the attitude propagation, within the dispersion range of the attitude determination system performance of Satellite Control Center of Brazil National Research Institute.
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PREFACE: The Science of Making Torque from Wind 2014 (TORQUE 2014)
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
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Study on Monitoring Rock Burst through Drill Pipe Torque
Directory of Open Access Journals (Sweden)
Zhonghua Li
2015-01-01
Full Text Available This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the analysis, a new device for testing drill pipe torque is developed and a series of experiments is performed under different conditions; the results show that drill pipe torque linearly increases with the increase of coal stress and coal strength; the faster the drilling speed, the larger the drill pipe torque, and vice versa. When monitoring rock burst by drill pipe torque method, the index of rock burst is regarded as a function in which coal stress index and coal strength index are principal variables. The results are important for the forecast of rock burst in coal mine.
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FRICTION TORQUE IN THE SLIDE BEARINGS
Directory of Open Access Journals (Sweden)
BONDARENKO L. N.
2016-09-01
Full Text Available Summary. Problem statement. Until now slide bearings are used widely in engineering. But the calculation is made on obsolete method that is based on undetermined parameters such as wear of the bearing shell. It is accepted in the literature that if the shaft and liner material are homogeneous, the workpiece surface are cylindrical as they wear and contact between them occurs at all points contact arc. Research objective. The purpose of this study is determine a friction torque in the slide bearings of power-basis parameters. Conclusions. Since the friction is primarily responsible for wear of cinematic pairs “pin – liner” and “pivot – liner” slide bearings. It is shown that the friction torquesof angles wrap, that are obtained by the formulas and given in literature, are not only qualitatively but also quantitatively, namely, the calculation by literature to the formulas the friction torques are proportional to the angle wrap and the calculation by improved formulas the friction torques are inversely proportional to the angle wrap due to the reduction the normal pressure. Underreporting friction torque at large angle wrap is between 40 and 15 %. The difference in the magnitude of friction torque in the run-in and run-out cinematic pairs with real method of machining is 2...3 %, which it is possible to declare of reducing the finish of contacting surface of slide bearings.
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Magnon-mediated Dzyaloshinskii-Moriya torque in homogeneous ferromagnets
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.
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Directory of Open Access Journals (Sweden)
Braulio Pasternak-Júnior
2012-02-01
Full Text Available OBJECTIVE: This study assessed the muscular activity during root canal preparation through kinematics, kinetics, and electromyography (EMG. MATERIAL AND METHODS: The operators prepared one canal with RaCe rotary instruments and another with Flexo-files. The kinematics of the major joints was reconstructed using an optoelectronic system and electromyographic responses of the flexor carpi radialis, extensor carpi radialis, brachioradialis, biceps brachii, triceps brachii, middle deltoid, and upper trapezius were recorded. The joint torques of the shoulder, elbow and wrist were calculated using inverse dynamics. In the kinematic analysis, angular movements of the wrist and elbow were classified as low risk factors for work-related musculoskeletal disorders. With respect to the shoulder, the classification was medium-risk. RESULTS: There was no significant difference revealed by the kinetic reports. The EMG results showed that for the middle deltoid and upper trapezius the rotary instrumentation elicited higher values. The flexor carpi radialis and extensor carpi radialis, as well as the brachioradialis showed a higher value with the manual method. CONCLUSION: The muscular recruitment for accomplishment of articular movements for root canal preparation with either the rotary or manual techniques is distinct. Nevertheless, the rotary instrument presented less difficulty in the generation of the joint torque in each articulation, thus, presenting a greater uniformity of joint torques.
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Góes, Suelen M; Stefanello, Joice M F; Homann, Diogo; Lodovico, Angélica; Hubley-Kozey, Cheryl L; Rodacki, André L F
2016-11-01
Góes, SM, Stefanello, JMF, Homann, D, Lodovico, A, Hubley-Kozey, CL, and Rodacki, ALF. Torque and muscle activation impairment along with insulin resistance are associated with falls in women with fibromyalgia. J Strength Cond Res 30(11): 3155-3164, 2016-Fibromyalgia (FM) is a chronic pain condition associated with reduced muscle strength, which can lead to functional incapacity and higher risk of falls. The purpose of the study was to compare maximal ankle joint torque, muscle activation, and metabolic changes between women with and without FM. In addition, the relationship between those aspects and retrospectively reported falls in women with FM was determined. Twenty-nine middle-aged women with FM and 30 controls were recruited. Fall history, pain intensity, and pain threshold were assessed. Plasma glucose levels and insulin resistance (IR) were determined. Peak torque and rate of torque development (RTD) were calculated, and muscle activation was assessed from maximum isometric voluntary ankle dorsiflexion and plantar flexion contractions. In addition, voluntary muscle activation failure of the anterior tibialis muscle during maximal dorsiflexion was calculated. When compared to controls, women with FM reported higher number of retrospectively reported falls, exhibited higher IR, showed reduced plantar flexion and dorsiflexion RTD, had lower plantar flexion peak torque, and demonstrated more antagonist coactivation and higher muscle activation failure (p ≤ 0.05). Higher muscle activation failure was explained by glucose level and pain intensity (adj R = 0.28; p ≤ 0.05). Reduced plantar flexion and dorsiflexion peak torque explained 80% of retrospectively reported falls variance; also, high antagonist coactivation (odds ratio [OR] = 1.6; p ≤ 0.05) and high IR (OR = 1.8; p ≤ 0.05) increased the chance of falls in the FM group. A combination of metabolic factors and muscle function increased the odds of retrospectively reporting a fall in FM. Both aspects
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Current-induced Rashba spin orbit torque in silicene
Energy Technology Data Exchange (ETDEWEB)
Chen, Ji, E-mail: muze7777@hdu.edu.cn [Department of Mathematics, School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China); Peng, Yingzi [Department of Physics, School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China); Center for Integrated Spintronic Devices, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhou, Jie [Department of Mathematics, School of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)
2017-06-15
Highlights: • The spin dynamics of a ferromagnetic layer coupled to a silicene is investigated. • The Rashba spin orbit torque is obtained and the well-known LLG equation is modified. • The explicit forms of spin orbit torques in Domain Wall and vortex is also obtained. - Abstract: We study theoretically the spin torque of a ferromagnetic layer coupled to a silicene in the presence of the intrinsic Rashba spin orbit coupling (RSOC) effect. By using gauge field method, we find that under the applied current, the RSOC can induce an effective field which will result in the spin precession of conduction electron without applying any magnetic field. We also derive the spin torques due to the RSOC, which generalize the Landau-Lifshitz-Gilbert (LLG) equation. The spin torques are related to the applied current, the carrier density and Rashba strength of the system.
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Manipulating the voltage dependence of tunneling spin torques
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.
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Gill, Jaspret
2018-01-01
Individuals may stand with a range of ankle angles. Furthermore, shoes or floor surfaces may elevate or depress their heels. Here we ask how these situations impact ankle stiffness and balance. We performed two studies (each with 10 participants) in which the triceps surae, Achilles tendon and aponeurosis were stretched either passively, by rotating the support surface, or actively by leaning forward. Participants stood freely on footplates which could rotate around the ankle joint axis. Brief, small stiffness-measuring perturbations (torque or passive stretch. Sway was minimally affected by stretch or lean, suggesting that this did not underlie the alterations in stiffness. In quiet stance, maximum ankle stiffness is limited by the tendon. As tendon strain increases, it becomes stiffer, causing an increase in overall ankle stiffness, which would explain the effects of leaning. However, stiffness also increased considerably with passive stretch, despite a modest torque increase. We discuss possible explanations for this increase. PMID:29558469
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Energy Technology Data Exchange (ETDEWEB)
Danyluk, P.; Gutoski, G. [Coltec Industries Inc., Fairbanks Morse Engine Division (United States); Chen, S.K. [PEI Consultants (United States)
1998-12-31
This paper describes the benefits of sequential turbocharging in improving the operating envelope of a medium speed diesel engine. In particular, the high torque, low speed performance envelope can be greatly extended over that of a standard medium speed engine and, in addition, can offer improved operating range over what has been achieved with compressor air bypass/waste gate systems. This paper compares the three approaches on the basis of possible operating envelopes for a specific application, the new U.S. Navy LPD-17 amphibious assault ship, which has a very demanding requirement for high torque at low engine speed and low ambient temperatures. Comparison is made to the earlier approach to extend the operating envelope on the U.S. Navy LSD-41 class engines. The LSD-41 fleet has been in service since 1985 running with a compressor air bypass system developed jointly by Lockheed Shipyard and Coltec Industries for the U.S. Navy. (au)
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Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays
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.
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DIFFERENCES IN THE KNEE TORQUE BETWEEN HIGH- AND LOW-BAR BACK SQUAT TECHNIQUES. A PILOT STUDY
Directory of Open Access Journals (Sweden)
Janez Logar
2015-01-01
Full Text Available Purpose: The squat is one of the most frequently used exercises in sports training and competitions. There are several squat variations: i the front squat (FS, ii the high-bar back squat (HBS and iii the low-bar back squat (LBS. As the biomechanics of the LBS technique have been studied to a lesser extent, therefore the purpose of this pilot study was to analyze the differences in knee joint net muscle torque between the HBS and LBS. Methods: One healthy male subject (180.0 cm, 76.0 kg, 26 years performed 10 steady paced squats (5 HBS and 5 LBS with additional weight (40.4 kg to a 90° knee angle. Kinematic and kinetic data were gathered using a high-speed camcorder and a force plate, respectively. The maximal and average knee joint net muscle torques (Mmax and Mavg were then calculated via 2-dimensional inverse dynamics. Results: A significantly greater Mavg was observed using the HBS technique as compared to the LBS, both during the entire range of the squat (MavgHBS = 221.6 ± 5.1 Nm, MavgLBS= 203.3 ± 10.2 Nm; p = 0.026 as well as during the eccentric (MavgHBS = 226.0 ± 5.9 Nm, MavgLBS= 202.0 ± 14.0 Nm; p = 0.043 and concentric (MavgHBS = 216.2 ± 3.6 Nm, MavgLBS= 205.0 ± 7.9 Nm; p = 0.021 phase separately. Conclusions: It can be concluded that the lower Mavg during the LBS could be due to the load transfer to the hip joint, most likely because of the greater anterior tilt of the torso, which is a direct response to a lower and more posterior bar placement on the back to finally maintain an unchanged centre of mass. Confirmation of these findings in a larger sample would imply that the LBS could be a more appropriate squat technique when knee joint relief is desired.
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Analysis of thrust/torque signature of MOV
International Nuclear Information System (INIS)
Ryu, Ho Geun; Park, Seong Keun; Kim, Dae Woong
2001-01-01
For the evaluation of operability of MOV(Motor Operated Valve), the precision prediction of thrust/torque acting on the valve is important. In this paper, the analytical prediction method of thrust/torque was proposed. The design basis stem thrust calculation typically considers the followings: packing thrust, stem rejection load, design basis differential pressure load. In general, test results show that temperature, pressure, fluid type, and differential pressure, independently and combination, all have an effect on the friction factor. The prediction results of thrust/torque are well agreement with dynamic test results
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Corotation torques in the solar nebula - the cutoff function
International Nuclear Information System (INIS)
Ward, W.R.
1989-01-01
The behavior of high-order corotation resonances in a disk of finite thickness is examined. The torque exerted at an mth-order resonance is determined by employing a vertically averaged disturbing function, and the ratio of this torque to that exerted on a cold, two-dimensional disk is identified as the so-called torque cutoff function. This function is then used to calculate contributions from the corotation torques to eccentricity variations of a perturber's orbit assumed orbiting in the disk. 11 references
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Seweryn, Karol; Grassmann, Kamil; Ciesielska, Monika; Rybus, Tomasz; Turek, Michal
2013-09-01
One of the most critical element in the orbital manipulators are kinematic joints. Joints must be adapted to work in tough conditions of space environment and must ensure the greatest efficiency and work without backlash. At the Space Mechatronics and Robotics Laboratory (LMRS) of the Space Research Centre, PAS our team designed and built a lightweight kinematic pair based on a new concept. The new concept is based on the epicycloid two-stage gearbox with torque motor. In this paper we have focused on optimization of the joint design for space application. The optimization was focused on the minimization of the mass and backlash effects and on maximizing the joint efficiency.
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Technical Errors May Affect Accuracy of Torque Limiter in Locking Plate Osteosynthesis.
Savin, David D; Lee, Simon; Bohnenkamp, Frank C; Pastor, Andrew; Garapati, Rajeev; Goldberg, Benjamin A
2016-01-01
In locking plate osteosynthesis, proper surgical technique is crucial in reducing potential pitfalls, and use of a torque limiter makes it possible to control insertion torque. We conducted a study of the ways in which different techniques can alter the accuracy of torque limiters. We tested 22 torque limiters (1.5 Nm) for accuracy using hand and power tools under different rotational scenarios: hand power at low and high velocity and drill power at low and high velocity. We recorded the maximum torque reached after each torque-limiting event. Use of torque limiters under hand power at low velocity and high velocity resulted in significantly (P torque and subsequent complications. For torque limiters, the most reliable technique involves hand power at slow velocity or drill power with careful control of insertion speed until 1 torque-limiting event occurs.
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A rotary pneumatic actuator for the actuation of the exoskeleton knee joint
Directory of Open Access Journals (Sweden)
Jobin Varghese
2017-07-01
Full Text Available Rotary pneumatic actuators that are made out of linear one are always best suited for exoskeleton joint actuation due to its inherent power to weight ratio. This work is a modified version of knee actuation system that has already been developed and major modifications are made in order to make it more suitable for human wearing and also to reduce its bulkiness and complexity. The considered actuator system is a rotary actuator where a pulley converts the linear motion of the standard pneumatic piston into the rotary motion. To prove the capability of the actuator, its performance characteristics such as torque and power produced are compared to the required torque and power at the knee joint of the exoskeleton in swing phase and are found to be excellent. The two-way analysis of variance (ANOVA is performed to find the effect of the throat area valve on knee angle. The ANOVA shows the significant effect of the throat area variation on the knee angle flexion made by the proposed actuator. A relationship between the throat area of flow control valve, that is connected to the exit port of the direction control valve, and angular displacement of the knee joint has been formulated. This relationship can be used to design a control system to regulate the mass flow rate of air at the exit and hence the angular velocity of the knee joint can be controlled. Keywords: Driven pulley, Flow control valve, Rotary, Pneumatic cylinder
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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 ...
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Kamiya, Tomoaki; Kura, Hideji; Suzuki, Daisuke; Uchiyama, Eiichi; Fujimiya, Mineko; Yamashita, Toshihiko
2009-12-01
The roles of each ligament supporting the subtalar joint have not been clarified despite several biomechanical studies. The effects of ankle braces on subtalar instability have not been shown. The ankle brace has a partial effect on restricting excessive motion of the subtalar joint. Controlled laboratory study. Ten normal fresh-frozen cadaveric specimens were used. The angular motions of the talus were measured via a magnetic tracking system. The specimens were tested while inversion and eversion forces, as well as internal and external rotation torques, were applied. The calcaneofibular ligament, cervical ligament, and interosseous talocalcaneal ligament were sectioned sequentially, and the roles of each ligament, as well as the stabilizing effects of the ankle brace, were examined. Complete sectioning of the ligaments increased the angle between the talus and calcaneus in the frontal plane to 51.7 degrees + or - 11.8 degrees compared with 35.7 degrees + or - 6.0 degrees in the intact state when inversion force was applied. There was a statistically significant difference in the angles between complete sectioning of the ligaments and after application of the brace (34.1 degrees + or - 7.3 degrees ) when inversion force was applied. On the other hand, significant differences in subtalar rotation were not found between complete sectioning of the ligaments and application of the brace when internal and external rotational torques were applied. The ankle brace limited inversion of the subtalar joint, but it did not restrict motion after application of internal or external rotational torques. In cases of severe ankle sprains involving the calcaneofibular ligament, cervical ligament, and interosseous talocalcaneal ligament injuries, application of an ankle brace might be less effective in limiting internal-external rotational instabilities than in cases of inversion instabilities in the subtalar joint. An improvement in the design of the brace is needed to restore
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Directory of Open Access Journals (Sweden)
Carole Cometti
Full Text Available This study compared knee extensors' neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT and doublet frequency train (DFT. Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd and tetanic contractions at 80-Hz (P80 and 20-Hz (P20 were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no difference was obtained between the two stimulation patterns for MVC and evoked torque decreases. Measurements conducted in the subgroup depicted a significant reduction of Pd, P20 and P80. Statistical analyses also revealed bigger P20 immediate reductions after CFT than after DFT. We concluded that DFT could be a useful stimulation pattern to produce and maintain greater force with quite similar fatigue than CFT.
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The acting wear mechanisms on metal-on-metal hip joint bearings: in-vitro results
Wimmer, M.A.; Loos, J.; Nassutt, R.; Heitkemper, M.; Fischer, A.
2001-01-01
Metal-on-metal (MOM) hip joint bearings are currently under discussion as alternatives to metal-on-polymer (MOP) bearings. Some criteria under scrutiny are the wear resistance, the influence of wear particles on the surrounding tissue, as well as the frictional torque. In order to understand and
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Remote calibration of torque wrenches in a hostile environment
Griffin, D. M.
1982-03-01
A relatively simple device is described which provides the capability for remote comparison of torque wrenches over a limited range. The device, properly used, provides calibration capability for most inch pound and foot pound range torque wrenches. For purposes of this discussion, the device itself was developed specifically for adapting an existing torque measuring system with torque wrenches in hostile environment. A gloved access port is utilized to manipulate the fixture while a viewing window and mirror are used to make visual comparisons. Click type wrenches do not require use of the mirror.
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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.
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Torque-onset determination: Unintended consequences of the threshold method.
Dotan, Raffy; Jenkins, Glenn; O'Brien, Thomas D; Hansen, Steve; Falk, Bareket
2016-12-01
Compared with visual torque-onset-detection (TOD), threshold-based TOD produces onset bias, which increases with lower torques or rates of torque development (RTD). To compare the effects of differential TOD-bias on common contractile parameters in two torque-disparate groups. Fifteen boys and 12 men performed maximal, explosive, isometric knee-extensions. Torque and EMG were recorded for each contraction. Best contractions were selected by peak torque (MVC) and peak RTD. Visual-TOD-based torque-time traces, electromechanical delays (EMD), and times to peak RTD (tRTD) were compared with corresponding data derived from fixed 4-Nm- and relative 5%MVC-thresholds. The 5%MVC TOD-biases were similar for boys and men, but the corresponding 4-Nm-based biases were markedly different (40.3±14.1 vs. 18.4±7.1ms, respectively; ptorque kinetics tended to be faster than the boys' (NS), but the 4-Nm-based kinetics erroneously depicted the boys as being much faster to any given %MVC (p<0.001). When comparing contractile properties of dissimilar groups, e.g., children vs. adults, threshold-based TOD methods can misrepresent reality and lead to erroneous conclusions. Relative-thresholds (e.g., 5% MVC) still introduce error, but group-comparisons are not confounded. Copyright © 2016 Elsevier Ltd. All rights reserved.
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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.
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Thangavel, Pavithra; Vidhya, S; Li, Junhua; Chew, Effie; Bezerianos, Anastasios; Yu, Haoyong
2017-07-01
Since manual rehabilitation therapy can be taxing for both the patient and the physiotherapist, a gait rehabilitation robot has been built to reduce the physical strain and increase the efficacy of the rehabilitation therapy. The prototype of the gait rehabilitation robot is designed to provide assistance while walking for patients with abnormal gait pattern and it can also be used for rehabilitation therapy to restore an individual's normal gait pattern by aiding motor recovery. The Gait Rehabilitation Robot uses gait event based synchronization, which enables the exoskeleton to provide synchronous assistance during walking that aims to reduce the lower-limb muscle activation. This study emphasizes on the biomechanical effects of assisted walking on the lower limb by analyzing the EMG signal, knee joint kinematics data that was collected from the right leg during the various experimental conditions. The analysis of the measured data shows an improved knee joint trajectory and reduction in muscle activity with assistance. The result of this study does not only assess the functionality of the exoskeleton but also provides a profound understanding of the human-robot interaction by studying the effects of assistance on the lower limb.
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Diffusion of torqued active particles
Sandoval, Mario; Lauga, Eric
2012-11-01
Motivated by swimming microorganisms whose trajectories are affected by the presence of an external torque, we calculate the diffusivity of an active particle subject to an external torque and in a fluctuating environment. The analytical results are compared with Brownian dynamics simulations showing excellent agreement between theory and numerical experiments. This work was funded in part by the Consejo Nacional de Ciencia y Tecnologia of Mexico (Conacyt postdoctoral fellowship to M. S.) and the US National Science Foundation (Grant CBET-0746285 to E.L.).
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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.
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Intrinsic magnetic torque at low magnetic induction
International Nuclear Information System (INIS)
Doria, M.M.; Oliveira, I.G. de.
1993-01-01
Using anisotropic London theory the intrinsic magnetic torque for extreme type II uniaxial superconductors for any value of the magnetic induction is obtained. It is considered the vortex lines straight and take into account the contribution of the supercurrents flowing inside the vortex core within the London theory. It is shown that the interline and intra line free energies give opposite torque contributions, the first drives the magnetic induction parallel to the superconductor's axis of symmetry and the second orthogonal to it. At high magnetic induction torque expression obtained generalizes V. Kogan's formula since it has no free parameters other than the anisotropy γ = m 1 /m 3 and the Ginzburg-Landau parameter κ. At low magnetic induction it is proposed a way to observe vortex chains effects in the total torque based on the fact that London theory is linear and the energy to make a single vortex line in space is independent of the magnetic induction. (author)
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Excitable particles in an optical torque wrench
Pedaci, Francesco; Huang, Zhuangxiong; van Oene, Maarten; Barland, Stephane; Dekker, Nynke H.
2011-03-01
The optical torque wrench is a laser trapping technique capable of applying and directly measuring torque on microscopic birefringent particles using spin momentum transfer, and has found application in the measurement of static torsional properties of biological molecules such as single DNAs. Motivated by the potential of the optical torque wrench to access the fast rotational dynamics of biological systems, a result of its all-optical manipulation and detection, we focus on the angular dynamics of the trapped birefringent particle, demonstrating its excitability in the vicinity of a critical point. This links the optical torque wrench to nonlinear dynamical systems such as neuronal and cardiovascular tissues, nonlinear optics and chemical reactions, all of which display an excitable binary (`all-or-none') response to input perturbations. On the basis of this dynamical feature, we devise and implement a conceptually new sensing technique capable of detecting single perturbation events with high signal-to-noise ratio and continuously adjustable sensitivity.
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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.
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Directory of Open Access Journals (Sweden)
Vinay KUMAR
2011-06-01
Full Text Available This paper proposes an algorithm for direct flux and torque controlled three phase induction motor drive systems. This method is based on control of slip speed and decoupled between amplitude and angle of reference stator flux for determining required stator voltage vector. In this proposes model, integrator unit is not required to generate the reference stator flux angle for calculating required stator voltage vector, hence it eliminates the initial values problems in real time. Within the given sampling time, flux as well as torque errors are controlled by stator voltage vector which is evaluated from reference stator flux. The direct torque control is achieved by reference stator flux angle which is generates from instantaneous slip speed angular frequency and stator flux angular frequency. The amplitude of the reference stator flux is kept constant at rated value. This technique gives better performance in three-phase induction motor than conventional technique. Simulation results for 3hp induction motor drive, for both proposed and conventional techniques, are presented and compared. From the results it is found that the stator current, flux linkage and torque ripples are decreased with proposed technique.
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Spin-transfer torque in spin filter tunnel junctions
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.
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Eddy Current Sensing of Torque in Rotating Shafts
Varonis, Orestes J.; Ida, Nathan
2013-12-01
The noncontact torque sensing in machine shafts is addressed based on the stress induced in a press-fitted magnetoelastic sleeve on the shaft and eddy current sensing of the changes of electrical conductivity and magnetic permeability due to the presence of stress. The eddy current probe uses dual drive, dual sensing coils whose purpose is increased sensitivity to torque and decreased sensitivity to variations in distance between probe and shaft (liftoff). A mechanism of keeping the distance constant is also employed. Both the probe and the magnetoelastic sleeve are evaluated for performance using a standard eddy current instrument. An eddy current instrument is also used to drive the coils and analyze the torque data. The method and sensor described are general and adaptable to a variety of applications. The sensor is suitable for static and rotating shafts, is independent of shaft diameter and operational over a large range of torques. The torque sensor uses a differential eddy current measurement resulting in cancellation of common mode effects including temperature and vibrations.
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Spin-transfer torque in spin filter tunnel junctions
Ortiz Pauyac, Christian; Kalitsov, Alan; Manchon, Aurelien; Chshiev, Mairbek
2014-01-01
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.
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Cogging Torque Reduction Techniques for Spoke-type IPMSM
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.
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Standard practice for torque calibration of testing machines and devices
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...
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Dynamics of domain wall driven by spin-transfer torque
International Nuclear Information System (INIS)
Chureemart, P.; Evans, R. F. L.; Chantrell, R. W.
2011-01-01
Spin-torque switching of magnetic devices offers new technological possibilities for data storage and integrated circuits. We have investigated domain-wall motion in a ferromagnetic thin film driven by a spin-polarized current using an atomistic spin model with a modified Landau-Lifshitz-Gilbert equation including the effect of the spin-transfer torque. The presence of the spin-transfer torque is shown to create an out-of-plane domain wall, in contrast to the external-field-driven case where an in-plane wall is found. We have investigated the effect of the spin torque on domain-wall displacement, domain-wall velocity, and domain-wall width, as well as the equilibration time in the presence of the spin-transfer torque. We have shown that the minimum spin-current density, regarded as the critical value for domain-wall motion, decreases with increasing temperature.
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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.
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Spin-Orbit Torques in Co/Pd Multilayer Nanowires
Jamali, Mahdi; Narayanapillai, Kulothungasagaran; Qiu, Xuepeng; Loong, Li Ming; Manchon, Aurelien; Yang, Hyunsoo
2013-01-01
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.
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Spin-Orbit Torques in Co/Pd Multilayer Nanowires
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.
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Bowersock, Collin D; Willy, Richard W; DeVita, Paul; Willson, John D
2017-10-01
The purpose of this study was to examine the effects of step length and foot strike pattern along with their interaction on tibiofemoral joint (TFJ) and medial compartment TFJ kinetics during running. Nineteen participants ran with a rear foot strike pattern at their preferred speed using a short (-10%), preferred, and long (+10%) step length. These step length conditions were then repeated using a forefoot strike pattern. Regardless of foot strike pattern, a 10% shorter step length resulted in decreased peak contact force, force impulse per step, force impulse per kilometre, and average loading rate at the TFJ and medial compartment, while a 10% increased step length had the opposite effects (all P forefoot strike pattern significantly lowered TFJ and medial compartment TFJ average loading rates compared with a rear foot strike pattern (both forefoot strike pattern produced the greatest reduction in peak medial compartment contact force (P < 0.05). Knowledge of these running modification effects may be relevant to the management or prevention of TFJ injury or pathology among runners.
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Chen, Yoa; Yu, Yong; He, Cheng-qi
2015-11-01
To establish correlations between joint proprioception, muscle flexion and extension peak torque, and functional ability in patients with knee osteoarthritis (OA). Fifty-six patients with symptomatic knee OA were recruited in this study. Both proprioceptive acuity and muscle strength were measured using the isomed-2000 isokinetic dynamometer. Proprioceptive acuity was evaluated by establishing the joint motion detection threshold (JMDT). Muscle strength was evaluated by Max torque (Nm) and Max torque/weight (Nm/ kg). Functional ability was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index physical function (WOMAC-PF) questionnaire. Correlational analyses were performed between proprioception, muscle strength, and functional ability. A multiple stepwise regression model was established, with WOMAC-PF as dependent variable and patient age, body mass index (BMI), visual analogue scale (VAS)-score, mean grade for Kellgren-Lawrance of both knees, mean strength for quadriceps and hamstring muscles of both knees, and mean JMDT of both knees as independent variables. Poor proprioception (high JMDT) was negatively correlated with muscle strength (Pcoefficient (B) = 0.385, P<0.50 and high VAS-scale score (B=0.347, P<0.05) were significant predictors of WOMAC-PF score. Patients with poor proprioception is associated with poor muscle strength and limitation in functional ability. Patients with symptomatic OA of knees commonly endure with moderate to considerable dysfunction, which is associated with poor proprioception (high JMDT) and high VAS-scale score.
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Current induced torques and interfacial spin-orbit coupling: Semiclassical modeling
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.
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Spin-torque generation in topological insulator based heterostructures
Fischer, Mark H.; Vaezi, Abolhassan; Manchon, Aurelien; Kim, Eun-Ah
2016-01-01
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
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Robust spin transfer torque in antiferromagnetic tunnel junctions
Saidaoui, Hamed Ben Mohamed; Waintal, Xavier; Manchon, Aurelien
2017-01-01
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
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Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals
Li, Hang; Wang, Xuhui; Manchon, Aurelien
2016-01-01
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.
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Valley-dependent spin-orbit torques in two-dimensional hexagonal crystals
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.
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Sanders, Anthony P; Raeymaekers, Bart
2014-10-01
A prosthetic knee joint typically comprises a cobalt-chromium femoral component that articulates with a polyethylene tibial insert. A locking screw may be used to prevent micromotion and dislodgement of the tibial insert from the tibial tray. Screw loosening and back-out have been reported, but the mechanism that causes screw loosening is currently not well understood. In this paper, we experimentally evaluate the effect of polyethylene creep on the preload of the locking screw. We find that the preload decreases significantly as a result of polyethylene creep, which reduces the torque required to loosen the locking screw. The torque applied to the tibial insert due to internal/external rotation within the knee joint during gait could thus drive locking screw loosening and back-out. The results are very similar for different types of polyethylene. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Granito, Renata Neves; Aveiro, Mariana Chaves; Renno, Ana Claudia Muniz; Oishi, Jorge; Driusso, Patricia
2012-01-01
Increased thoracic kyphosis is one of the most disfiguring consequences of osteoporotic spine fractures in the elderly. However, mechanisms involved in the increasing of the kyphosis degree among osteoporotic women are not completely understood. Then, the aims of this cross-sectional preliminary study were comparing thoracic kyphosis degree, trunk muscle peak torque and joint position sense among healthy and osteoporotic elderly women and investigating possible factors affecting the kyphosis degree. Twenty women were selected for 2 groups: healthy (n=10) and osteoporotic (n=10) elderly women. Bone mineral density (BMD), thoracic kyphosis degree, trunk muscles peak torque and joint position sense were measured. Differences among groups were analyzed by Student's Test T for unpaired data. Correlations between variables were performed by Pearson's coefficient correlation. The level of significance used for all comparisons was 5% (p≤0.05). We observed that the osteoporotic women demonstrated a significantly higher degree of kyphosis and lower trunk extensor muscle peak torque. Moreover, it was found that the BMD had a negative correlation with the thoracic kyphosis degree. Kyphosis degree showed a negative correlation between extensor muscle strength and joint position sense index. This study suggests that lower BMD may be associated to higher degree of kyphosis degree, lower trunk extensors muscle strength and an impaired joint position sense. It is also suggested that lower extensor muscle strength may be a factor that contributes to the increasing in kyphosis thoracic degree. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
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Prevailing Torque Locking Feature in Threaded Fasteners Using Anaerobic Adhesive
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.
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Manipulating the voltage dependence of tunneling spin torques
Manchon, Aurelien
2012-01-01
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
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Magnon-mediated Dzyaloshinskii-Moriya torque in homogeneous ferromagnets
Manchon, Aurelien; Ndiaye, Papa Birame; Moon, Jung-Hwan; Lee, Hyun-Woo; Lee, Kyung-Jin
2014-01-01
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
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Reconstruction of Twist Torque in Main Parachute Risers
Day, Joshua D.
2015-01-01
The reconstruction of twist torque in the Main Parachute Risers of the Capsule Parachute Assembly System (CPAS) has been successfully used to validate CPAS Model Memo conservative twist torque equations. Reconstruction of basic, one degree of freedom drop tests was used to create a functional process for the evaluation of more complex, rigid body simulation. The roll, pitch, and yaw of the body, the fly-out angles of the parachutes, and the relative location of the parachutes to the body are inputs to the torque simulation. The data collected by the Inertial Measurement Unit (IMU) was used to calculate the true torque. The simulation then used photogrammetric and IMU data as inputs into the Model Memo equations. The results were then compared to the true torque results to validate the Model Memo equations. The Model Memo parameters were based off of steel risers and the parameters will need to be re-evaluated for different materials. Photogrammetric data was found to be more accurate than the inertial data in accounting for the relative rotation between payload and cluster. The Model Memo equations were generally a good match and when not matching were generally conservative.
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Hydrodynamic Torques and Rotations of Superparamagnetic Bead Dimers
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.
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High torque DC motor fabrication and test program
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.
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Predictive torque and flux control of an induction machine drive ...
Indian Academy of Sciences (India)
Finite-state model predictive control; fuzzy decision making; multi-objective optimization; predictive torque control. Abstract. Among the numerous direct torque control techniques, the finite-state predictive torque control (FS-PTC) has emerged as a powerful alternative as it offers the fast dynamic response and the flexibility to ...
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Electrode position markedly affects knee torque in tetanic, stimulated contractions.
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.
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Towards measuring quantum electrodynamic torque with a levitated nanorod
Xu, Zhujing; Bang, Jaehoon; Ahn, Jonghoon; Hoang, Thai M.; Li, Tongcang
2017-04-01
According to quantum electrodynamics, quantum fluctuations of electromagnetic fields give rise to a zero-point energy that never vanishes, even in the absence of electromagnetic sources. The interaction energy will not only lead to the well-known Casimir force but will also contribute to the Casimir torque for anisotropic materials. We propose to use an optically levitated nanorod in vacuum and a birefringent substrate to experimentally investigate the QED torque. We have previously observed the libration of an optically levitated non-spherical nanoparticle in vacuum and found it to be an ultrasensitive torque sensor. A nanorod with a long axis of 300nm and a diameter of 60nm levitated in vacuum at 10 (- 8) torr will have a remarkable torque detection sensitivity on the order of 10 (- 28) Nm/ √Hz, which will be sufficient to detect the Casimir torque. This work is partially supported by the National Science Foundation under Grant No.1555035-PHY.
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Direct shaft torque measurements in a transient turbine facility
International Nuclear Information System (INIS)
Beard, Paul F; Povey, Thomas
2011-01-01
This paper describes the development and implementation of a shaft torque measurement system for the Oxford Turbine Research Facility (formerly the Turbine Test Facility (TTF) at QinetiQ, Farnborough), or OTRF. As part of the recent EU TATEF II programme, the facility was upgraded to allow turbine efficiency measurements to be performed. A shaft torque measurement system was developed as part of this upgrade. The system is unique in that, to the authors' knowledge, it provided the first direct measurement of shaft torque in a transient turbine facility although the system has wider applicability to rotating test facilities in which power measurement is a requirement. The adopted approach removes the requirement to quantify bearing friction, which can be difficult to accurately calibrate under representative operating conditions. The OTRF is a short duration (approximately 0.4 s run time) isentropic light-piston facility capable of matching all of the non-dimensional parameters important for aerodynamic and heat studies, namely Mach number, Reynolds number, non-dimensional speed, stage pressure ratio and gas-to-wall temperature ratio. The single-stage MT1 turbine used for this study is a highly loaded unshrouded design, and as such is relevant to modern military, or future civil aero-engine design. Shaft torque was measured directly using a custom-built strain gauge-based torque measurement system in the rotating frame of reference. This paper describes the development of this measurement system. The system was calibrated, including the effects of temperature, to a traceable primary standard using a purpose-built facility. The bias and precision uncertainties of the measured torque were ±0.117% and ±0.183%, respectively. To accurately determine the shaft torque developed by a turbine in the OTRF, small corrections due to inertial torque (associated with changes in the rotational speed) and aerodynamic drag (windage) are required. The methods for performing these
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Heat Control via Torque Control in Friction Stir Welding
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).
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Anomalous magnetic torque in the heavy-fermion superconductor UBe13
International Nuclear Information System (INIS)
Schmiedeshoff, G.M.; Fisk, Z.; Smith, J.L.
1994-01-01
Measurements of the magnetic torque acting upon a single crystal of the heavy-fermion superconductor UBe 13 have been made at temperatures from 0.5 K to 30.0 K and in magnetic fields to 23 T using a capacitive magnetometer. We find that a large, anomalous contribution to the magnetic torque appears in at low temperatures and in high fields. The anomalous torque coexists with the superconducting state at low temperature. We propose that the anomalous torque reflects the existence of a field-induced magnetic phase transition. (orig.)
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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...
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Spin-transfer torque in tunnel junctions with ferromagnetic layer of finite thickness
International Nuclear Information System (INIS)
Wilczynski, M.
2011-01-01
Two components of the spin torque exerted on a free ferromagnetic layer of finite thickness and a half-infinite ferromagnetic electrode in single tunnel junctions have been calculated in the spin-polarized free-electron-like one-band model. It has been found that the torque oscillates with the thickness of ferromagnetic layer and can be enhanced in the junction with the special layer thickness. The bias dependence of torque components also significantly changes with layer thickness. It is non-symmetric for the normal torque, in contrast to the symmetric junctions with two identical half-infinite ferromagnetic electrodes. The asymmetry of the bias dependence of the normal component of the torque can be also observed in the junctions with different spin splitting of the electron bands in the ferromagnetic electrodes. - Research highlights: → The torque oscillates with the thickness of ferromagnetic layer. → Bias dependence of the torque changes with the layer thickness. → Bias dependence of the normal torque can be asymmetric.
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Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes
Saidaoui, Hamed Ben Mohamed; Manchon, Aurelien; Waintal, Xavier
2014-01-01
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.
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Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes
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.
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Bodnar, S Yu; Šmejkal, L; Turek, I; Jungwirth, T; Gomonay, O; Sinova, J; Sapozhnik, A A; Elmers, H-J; Kläui, M; Jourdan, M
2018-01-24
Using antiferromagnets as active elements in spintronics requires the ability to manipulate and read-out the Néel vector orientation. Here we demonstrate for Mn 2 Au, a good conductor with a high ordering temperature suitable for applications, reproducible switching using current pulse generated bulk spin-orbit torques and read-out by magnetoresistance measurements. Reversible and consistent changes of the longitudinal resistance and planar Hall voltage of star-patterned epitaxial Mn 2 Au(001) thin films were generated by pulse current densities of ≃10 7 A/cm 2 . The symmetry of the torques agrees with theoretical predictions and a large read-out magnetoresistance effect of more than ≃6% is reproduced by ab initio transport calculations.
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Design of digital load torque observer in hybrid electric vehicle
Sun, Yukun; Zhang, Haoming; Wang, Yinghai
2008-12-01
In hybrid electric vehicle, engine begain to work only when motor was in high speed in order to decrease tail gas emission. However, permanent magnet motor was sensitive to its load, adding engine to the system always made its speed drop sharply, which caused engine to work in low efficiency again and produced much more environment pollution. Dynamic load torque model of permanent magnet synchronous motor is established on the basic of motor mechanical equation and permanent magnet synchronous motor vector control theory, Full- digital load torque observer and compensation control system is made based on TMS320F2407A. Experiment results prove load torque observer and compensation control system can detect and compensate torque disturbing effectively, which can solve load torque disturbing and decrease gas pollution of hybrid electric vehicle.
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Four-bar linkage-based automatic tool changer: Dynamic modeling and torque optimization
International Nuclear Information System (INIS)
Lee, Sangho; Seo, TaeWon; Kim, Jong-Won; Kim, Jongwon
2017-01-01
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.
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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.
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Analyzing the installation angle error of a SAW torque sensor
International Nuclear Information System (INIS)
Fan, Yanping; Ji, Xiaojun; Cai, Ping
2014-01-01
When a torque is applied to a shaft, normal strain oriented at ±45° direction to the shaft axis is at its maximum, which requires two one-port SAW resonators to be bonded to the shaft at ±45° to the shaft axis. In order to make the SAW torque sensitivity high enough, the installation angle error of two SAW resonators must be confined within ±5° according to our design requirement. However, there are few studies devoted to the installation angle analysis of a SAW torque sensor presently and the angle error was usually obtained by a manual method. Hence, we propose an approximation method to analyze the angle error. First, according to the sensitive mechanism of the SAW device to torque, the SAW torque sensitivity is deduced based on the linear piezoelectric constitutive equation and the perturbation theory. Then, when a torque is applied to the tested shaft, the stress condition of two SAW resonators mounted with an angle deviating from ±45° to the shaft axis, is analyzed. The angle error is obtained by means of the torque sensitivities of two orthogonal SAW resonators. Finally, the torque measurement system is constructed and the loading and unloading experiments are performed twice. The torque sensitivities of two SAW resonators are obtained by applying average and least square method to the experimental results. Based on the derived angle error estimation function, the angle error is estimated about 3.447°, which is close to the actual angle error 2.915°. The difference between the estimated angle and the actual angle is discussed. The validity of the proposed angle error analysis method is testified to by the experimental results. (technical design note)
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AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT V, AUTOMATIC TRANSMISSIONS--TORQUE CONVERTER.
Human Engineering Inst., Cleveland, OH.
THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATION AND MAINTENANCE OF TORQUE CONVERTERS USED ON DIESEL POWERED VEHICLES. TOPICS ARE (1) FLUID COUPLINGS (LOCATION AND PURPOSE), (2) PRINCIPLES OF OPERATION, (3) TORQUE CONVERRS, (4) TORQMATIC CONVERTER, (5) THREE STAGE, THREE ELEMENT TORQUE CONVERTER, AND (6)…
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Medeiros, Flávia Vanessa; Bottaro, Martim; Vieira, Amilton; Lucas, Tiago Pires; Modesto, Karenina Arrais; Bo, Antonio Padilha L; Cipriano, Gerson; Babault, Nicolas; Durigan, João Luiz Quagliotti
2017-06-01
To test the hypotheses that, as compared with pulsed current with the same pulse duration, kilohertz frequency alternating current would not differ in terms of evoked-torque production and perceived discomfort, and as a result, it would show the same current efficiency. A repeated-measures design with 4 stimuli presented in random order was used to test 25 women: (1) 500-microsecond pulse duration, (2) 250-microsecond pulse duration, (3) 500-microsecond pulse duration and low carrier frequency (1 kHz), (4) 250-microsecond pulse duration and high carrier frequency (4 kHz). Isometric peak torque of quadriceps muscle was measured using an isokinetic dynamometer. Discomfort was measured using a visual analog scale. Currents with long pulse durations induced approximately 21% higher evoked torque than short pulse durations. In addition, currents with 500 microseconds delivered greater amounts of charge than stimulation patterns using 250-microsecond pulse durations (P torque and discomfort. However, neuromuscular electrical stimulation (NMES) with longer pulse duration induces higher NMES-evoked torque, regardless of the carrier frequency. Pulse duration is an important variable that should receive more attention for an optimal application of NMES in clinical settings.
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Evaluation Method for Fieldlike-Torque Efficiency by Modulation of the Resonance Field
Kim, Changsoo; Kim, Dongseuk; Chun, Byong Sun; Moon, Kyoung-Woong; Hwang, Chanyong
2018-05-01
The spin Hall effect has attracted a lot of interest in spintronics because it offers the possibility of a faster switching route with an electric current than with a spin-transfer-torque device. Recently, fieldlike spin-orbit torque has been shown to play an important role in the magnetization switching mechanism. However, there is no simple method for observing the fieldlike spin-orbit torque efficiency. We suggest a method for measuring fieldlike spin-orbit torque using a linear change in the resonance field in spectra of direct-current (dc)-tuned spin-torque ferromagnetic resonance. The fieldlike spin-orbit torque efficiency can be obtained in both a macrospin simulation and in experiments by simply subtracting the Oersted field from the shifted amount of resonance field. This method analyzes the effect of fieldlike torque using dc in a normal metal; therefore, only the dc resistivity and the dimensions of each layer are considered in estimating the fieldlike spin-torque efficiency. The evaluation of fieldlike-torque efficiency of a newly emerging material by modulation of the resonance field provides a shortcut in the development of an alternative magnetization switching device.
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Creative accomplishment of continuous TIP motor torque monitoring system in BWR plant
International Nuclear Information System (INIS)
Sun, C.H.; Li, I.N.; Liu, C.S.
1986-01-01
The Traveling In-core Probe (TIP) system is designed so delicate that the routine preventive maintenance - torque measurement is required to keep system operating properly. Normally, the torque measurement is performed by manually rotating torque wrench on the local TIP drive mechanism or using wattmeter during automatic operation. Whenever, either torque wrench or wattmeter measurement is performed, the high radiation exposure to maintenance personnel and mass manpower is expected. Because of this reason Taipower has developed a continuous TIP motor torque monitoring system to save manpower and minimize radiation exposure to maintenance personnel. This methods of TIP motor torque measurement will also predict TIP guide tube deterioration. (author)
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Induction machine Direct Torque Control system based on fuzzy adaptive control
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.
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Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry.
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; Ptorque (r ⩾ 0.99; Ptorque 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.
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Spin Transfer Torque in Graphene
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.
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Comparison of design and torque measurements of various manual wrenches.
Neugebauer, Jörg; Petermöller, Simone; Scheer, Martin; Happe, Arndt; Faber, Franz-Josef; Zoeller, Joachim E
2015-01-01
Accurate torque application and determination of the applied torque during surgical and prosthetic treatment is important to reduce complications. A study was performed to determine and compare the accuracy of manual wrenches, which are available in different designs with a large range of preset torques. Thirteen different wrench systems with a variety of preset torques ranging from 10 to 75 Ncm were evaluated. Three different designs were available, with a spring-in-coil or toggle design as an active mechanism or a beam as a passive mechanism, to select the preset torque. To provide a clinically relevant analysis, a total of 1,170 torque measurements in the range of 10 to 45 Ncm were made in vitro using an electronic torque measurement device. The absolute deviations in Ncm and percent deviations across all wrenches were small, with a mean of -0.24 ± 2.15 Ncm and -0.84% ± 11.72% as a shortfall relative to the preset value. The greatest overage was 8.2 Ncm (82.5%), and the greatest shortfall was 8.47 Ncm (46%). However, extreme values were rare, with 95th-percentile values of -1.5% (lower value) and -0.16% (upper value). A comparison with respect to wrench design revealed significantly higher deviations for coil and toggle-style wrenches than for beam wrenches. Beam wrenches were associated with a lower risk of rare extreme values thanks to their passive mechanism of achieving the selected preset torque, which minimizes the risk of harming screw connections.
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Spin-transfer torque generated by a topological insulator
Mellnik, A. R.; Lee, Joonsue; Richardella, Anthony R.; Grab, J. L.; Mintun, P. J.; Fischer, Mark H.; Vaezi, Abolhassan; Manchon, Aurelien; Kim, Eunah; Samarth, Nitin S.; Ralph, Daniel C.
2014-01-01
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
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Torque magnetometry by use of capacitance type transducer
International Nuclear Information System (INIS)
Braught, M.C.; Pechan, M.J.
1992-01-01
Interfacial anisotropy in magnetic multilayered samples comprised of nanometer thick magnetic layers alternating with non-magnetic layers is investigated by torque magnetometry in the temperature regime of 4 to 300K. The design, construction and use of a capacitance type transducer wherein the sample is mounted directly on with the plate of the capacitor, will be described. As a result the sample and transducer spatially coexist at the sample temperature in an applied external field, eliminating mechanical coupling from the cryogenic region to a remote room temperature transducer. The capacitor measuring the torque of the sample is paired with a reference capacitor. The difference between torque influenced capacitance and the reference is then determined by a differential transimpedance amplifier. Since both capacitors are physically identical variables such as temperature, vibration, orientation and external devices are minimized. Torques up to 300 dyne-cm can be measured with a sensitivity of 0.010 dyne-cm
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Torque Generation of Enterococcus hirae V-ATPase*
Ueno, Hiroshi; Minagawa, Yoshihiro; Hara, Mayu; Rahman, Suhaila; Yamato, Ichiro; Muneyuki, Eiro; Noji, Hiroyuki; Murata, Takeshi; Iino, Ryota
2014-01-01
V-ATPase (VoV1) converts the chemical free energy of ATP into an ion-motive force across the cell membrane via mechanical rotation. This energy conversion requires proper interactions between the rotor and stator in VoV1 for tight coupling among chemical reaction, torque generation, and ion transport. We developed an Escherichia coli expression system for Enterococcus hirae VoV1 (EhVoV1) and established a single-molecule rotation assay to measure the torque generated. Recombinant and native EhVoV1 exhibited almost identical dependence of ATP hydrolysis activity on sodium ion and ATP concentrations, indicating their functional equivalence. In a single-molecule rotation assay with a low load probe at high ATP concentration, EhVoV1 only showed the “clear” state without apparent backward steps, whereas EhV1 showed two states, “clear” and “unclear.” Furthermore, EhVoV1 showed slower rotation than EhV1 without the three distinct pauses separated by 120° that were observed in EhV1. When using a large probe, EhVoV1 showed faster rotation than EhV1, and the torque of EhVoV1 estimated from the continuous rotation was nearly double that of EhV1. On the other hand, stepping torque of EhV1 in the clear state was comparable with that of EhVoV1. These results indicate that rotor-stator interactions of the Vo moiety and/or sodium ion transport limit the rotation driven by the V1 moiety, and the rotor-stator interactions in EhVoV1 are stabilized by two peripheral stalks to generate a larger torque than that of isolated EhV1. However, the torque value was substantially lower than that of other rotary ATPases, implying the low energy conversion efficiency of EhVoV1. PMID:25258315
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[Influence of slot size on torque control].
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.
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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)
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Study on Monitoring Rock Burst through Drill Pipe Torque
Zhonghua Li; Liyuan Zhu; Wanlei Yin; Yanfang Song
2015-01-01
This paper presents a new method to identify the danger of rock burst from the response of drill pipe torque during drilling process to overcome many defects of the conventional volume of drilled coal rubble method. It is based on the relationship of rock burst with coal stress and coal strength. Through theoretic analysis, the change mechanism of drill pipe torque and the relationship of drill pipe torque with coal stress, coal strength, and drilling speed are investigated. In light of the a...
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Development of a New Small-Rated Reference Torque Wrench
Nishino, Atsuhiro; Ogushi, Koji; Ueda, Kazunaga
It is imperative that torque standard of small rated capacity is established and disseminated throughout Japanese industry. A 10 N·m dead weight torque standard machine (10-N·m-DWTSM) has been developed and evaluated at the National Metrology Institute of Japan (NMIJ), part of the National Institute of Advanced Industrial Science and Technology (AIST). By 2012, the relative expanded uncertainty of torque realized by the 10-N·m-DWTSM was estimated to be 6.6 × 10-5, with the coverage factor k begin equal to 2, in a range from 0.1 N·m to 10 N·m for calibrations of the torque measuring devices (TMDs). Calibration service for small-rated-capacity TMDs was started to disseminate the torque standard throughout Japanese industry. Here, there are two routes in the torque traceability system in Japan. One is the route for TMDs and the other one is the route for reference torque wrenches (RTWs). The torque standard in the form of RTWs has been disseminated in the range from 5 N·m to 5 kN·m by using the TSMs owned by NMIJ. There remains a strong demand to expand the calibration range of RTWs. To expand the range, we should develop the new high-accuracy small-rated-capacity RTW and evaluate its calibration method. In this study, a high-accuracy RTW (TP-5N-1109), which had a rated capacity of 5 N·m, was newly developed and calibrated with the 10-N·m-DWTSM to evaluate its characteristics. The ordinary calibration procedures adopted at NMIJ was investigated whether it was applicable to the small-rated-capacity RTWs. As a result, the TP-5N-1109 showed good performance in the creep testing, and its characteristic curves were draw for all cases of the calibration procedures. The repeatability in the calibration results was good. We clarified the problem with the calibration conditions of the small-rated-capacity RTW to calibrate it by three cases.
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MUSCLE WEAKNESS, FATIGUE, AND TORQUE VARIABILITY: EFFECTS OF AGE AND MOBILITY STATUS
KENT-BRAUN, JANE A.; CALLAHAN, DAMIEN M.; FAY, JESSICA L.; FOULIS, STEPHEN A.; BUONACCORSI, JOHN P.
2013-01-01
Introduction 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. Methods 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. Results 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). Conclusions These results suggest that increased torque variability may combine with baseline muscle weakness to limit function, particularly in older adults with mobility impairments. PMID:23674266
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Design of mechanical coxa joints based on three-degree-of-freedom spherical parallel manipulators
International Nuclear Information System (INIS)
Li, Yanbiao; Ji, Shiming; Wang, Zhongfei; Jin, Mingsheng; Liu, Yi; Jin, Zhenlin
2013-01-01
We addressed the issue of the design of mechanical coxa joints based on three-degree-of-freedom spherical parallel manipulators using the parameter statistics optimum method based on index atlases. The coxa joints have the advantages of high payload, high accuracy, and good technological efficiency. The first step of the design and prototyping used in this paper develops the direct and inverse displacement equations from the layout feature of the mechanical coxa joints. Then, the shapes of a constant-orientation workspace of the mechanical coxa joints are described, and the effects of the design parameters on the workspace volume are studied quantitatively. The next step deals with the graphical representation of the atlases that illustrates the relationship between performance evaluation index and design parameters based on the kinematics and torque analysis of the mechanical coxa joints. Finally, the geometric parameters of the coxa joints are obtained by the parameter statistics optimum method based on the index atlases. Considering assembly conditions, the design scheme of the mechanical coxa joints is developed, which provides a theoretical basis for the application of the mechanical coxa joints.
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Experimental and theoretical study of friction torque from radial ball bearings
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.
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New Cogging Torque Reduction Methods for Permanent Magnet Machine
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.
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Nguyen, Hung P; Dingwell, Jonathan B
2012-06-01
Determining how the human nervous system contends with neuro-motor noise is vital to understanding how humans achieve accurate goal-directed movements. Experimentally, people learning skilled tasks tend to reduce variability in distal joint movements more than in proximal joint movements. This suggests that they might be imposing greater control over distal joints than proximal joints. However, the reasons for this remain unclear, largely because it is not experimentally possible to directly manipulate either the noise or the control at each joint independently. Therefore, this study used a 2 degree-of-freedom torque driven arm model to determine how different combinations of noise and/or control independently applied at each joint affected the reaching accuracy and the total work required to make the movement. Signal-dependent noise was simultaneously and independently added to the shoulder and elbow torques to induce endpoint errors during planar reaching. Feedback control was then applied, independently and jointly, at each joint to reduce endpoint error due to the added neuromuscular noise. Movement direction and the inertia distribution along the arm were varied to quantify how these biomechanical variations affected the system performance. Endpoint error and total net work were computed as dependent measures. When each joint was independently subjected to noise in the absence of control, endpoint errors were more sensitive to distal (elbow) noise than to proximal (shoulder) noise for nearly all combinations of reaching direction and inertia ratio. The effects of distal noise on endpoint errors were more pronounced when inertia was distributed more toward the forearm. In contrast, the total net work decreased as mass was shifted to the upper arm for reaching movements in all directions. When noise was present at both joints and joint control was implemented, controlling the distal joint alone reduced endpoint errors more than controlling the proximal joint
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Self-consistent perturbed equilibrium with neoclassical toroidal torque in tokamaks
International Nuclear Information System (INIS)
Park, Jong-Kyu; Logan, Nikolas C.
2017-01-01
Toroidal torque is one of the most important consequences of non-axisymmetric fields in tokamaks. The well-known neoclassical toroidal viscosity (NTV) is due to the second-order toroidal force from anisotropic pressure tensor in the presence of these asymmetries. This work shows that the first-order toroidal force originating from the same anisotropic pressure tensor, despite having no flux surface average, can significantly modify the local perturbed force balance and thus must be included in perturbed equilibrium self-consistent with NTV. The force operator with an anisotropic pressure tensor is not self-adjoint when the NTV torque is finite and thus is solved directly for each component. This approach yields a modified, non-self-adjoint Euler-Lagrange equation that can be solved using a variety of common drift-kinetic models in generalized tokamak geometry. The resulting energy and torque integral provides a unique way to construct a torque response matrix, which contains all the information of self-consistent NTV torque profiles obtainable by applying non-axisymmetric fields to the plasma. This torque response matrix can then be used to systematically optimize non-axisymmetric field distributions for desired NTV profiles. Published by AIP Publishing.
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Patients' journeys through total joint replacement: patterns of medication use.
Johnson, Emma C; Horwood, Jeremy; Gooberman-Hill, Rachael
2014-06-01
Medication is used to manage pain that results from both osteoarthritis and total joint replacement (TJR). Research has provided insight into how people living with osteoarthritis use pain relief medication. However, it is not known whether elective TJR affects existing attitudes and behaviours with regard to pain medications. Using qualitative methods, the present study explored patterns of pain relief use around the time of TJR. In-depth face-to-face qualitative interviews were carried out with 24 patients two to four weeks after they had undergone TJR for hip or knee osteoarthritis. Participants were asked to reflect on their use of pain medication pre-surgery, while in hospital and while recovering from their operation at home. Transcripts of the audio-recorded interviews were imported into Atlas.ti® and thematic analysis was used. Attitudes to pain relief medication and their use are not static. Many participants change their use of pain medication around the time of surgery. This shift was influenced by interactions with health professionals and changing views on the acceptability, necessity and value of pain relief in helping to manage an altered pain experience. Understanding reasons for medication-taking behaviour during the journey through joint replacement may be helpful to health professionals. Health professionals have a fundamental role to play in challenging or reinforcing different treatment beliefs, which is the basis for effective use of pain relief over the pre- to postoperative period. © 2013 John Wiley & Sons, Ltd.
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A theoretical model of speed-dependent steering torque for rolling tyres
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.
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Magnetic moment of inertia within the torque-torque correlation model.
Thonig, Danny; Eriksson, Olle; Pereiro, Manuel
2017-04-19
An essential property of magnetic devices is the relaxation rate in magnetic switching which strongly depends on the energy dissipation. This is described by the Landau-Lifshitz-Gilbert equation and the well known damping parameter, which has been shown to be reproduced from quantum mechanical calculations. Recently the importance of inertia phenomena have been discussed for magnetisation dynamics. This magnetic counterpart to the well-known inertia of Newtonian mechanics, represents a research field that so far has received only limited attention. We present and elaborate here on a theoretical model for calculating the magnetic moment of inertia based on the torque-torque correlation model. Particularly, the method has been applied to bulk itinerant magnets and we show that numerical values are comparable with recent experimental measurements. The theoretical analysis shows that even though the moment of inertia and damping are produced by the spin-orbit coupling, and the expression for them have common features, they are caused by very different electronic structure mechanisms. We propose ways to utilise this in order to tune the inertia experimentally, and to find materials with significant inertia dynamics.
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A Computational Study on Hydrodynamic Torque Coefficients of a Butterfly Valve
International Nuclear Information System (INIS)
Lee, Do-Hwan; Park, Sung-Keun; Kang, Shin-Chul; Kim, Dae-Woong; Park, Ju-Yeop
2007-01-01
Butterfly valves have been widely used for on-off or control purposes in the process industry, since they provide quick opening and closing operation and good flow control characteristics. For the evaluation of the adequacy of valve operability and the actuator sizing, the required torque estimation is necessary. Since the principal contributing component of the require torque in the mid-stroke position is hydrodynamic torque, it is necessary to predict the torque properly under the actual flow conditions. The research on the prediction of the valve performance was led by EPRI (Electric Power Research Institute) in early 1990s. A performance prediction model was developed based on the experimental results and the free-streamline analysis by Sarpkaya. Recently, Kalsi Engineering carried out extended tests and developed the improved model. Variation of disk geometries and upstream flow conditions were tried to obtain accurate hydrodynamic torque coefficients. However, since the model is only commercially available, a general method to obtain hydrodynamic torque for butterfly valves is called for
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Proposed torque optimized behavior for digital speed control of induction motors
Energy Technology Data Exchange (ETDEWEB)
Metwally, H.M.B.; El-Shewy, H.M.; El-Kholy, M.M. [Zagazig Univ., Dept. of Electrical Engineering, Zagazig (Egypt); Abdel-Kader, F.E. [Menoufyia Univ., Dept. of Electrical Engineering, Menoufyia (Egypt)
2002-09-01
In this paper, a control strategy for speed control of induction motors with field orientation is proposed. The proposed method adjusts the output voltage and frequency of the converter to operate the motor at the desired speed with maximum torque per ampere at all load torques keeping the torque angle equal to 90 deg. A comparison between the performance characteristics of a 2 hp induction motor using three methods of speed control is presented. These methods are the proposed method, the direct torque control method and the constant V/f method. The comparison showed that better performance characteristics are obtained using the proposed speed control strategy. A computer program, based on this method, is developed. Starting from the motor parameters, the program calculates a data set for the stator voltage and frequency required to obtain maximum torque per ampere at any motor speed and load torque. This data set can be used by the digital speed control system of induction motors. (Author)
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Xu, Meimei; Liu, Guohai; Zhao, Wenxiang; Aamir, Nazir
2018-05-01
Torque ripple is one of the important issues for ferrite assisted synchronous reluctance motors (FASRMs). In this paper, an asymmetrical stator is proposed for the FASRM to reduce its torque ripple. In the proposed FASRM, an asymmetrical stator is designed by appropriately choosing the angle of the slot-opening shift. Meanwhile, its analytical torque expressions are derived. The results show that the proposed FASRM has an effective reduction in the cogging torque, reluctance torque ripple and total torque ripple. Moreover, it is easy to implement while the average torque is not sacrificed.
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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.
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Torque characteristics of a 122-centimeter butterfly valve with a hydro/pneumatic actuator
Lin, F. N.; Moore, W. I.; Lundy, F. E.
1981-01-01
Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.
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Prediction of a required dynamic torque for motor-operated butterfly valves
International Nuclear Information System (INIS)
Bae, J. H.; Lee, K. N.; Jeong, W. K.
2002-01-01
This study describes the methodology for predicting a required dynamic torque in motor-operated butterfly valves. The results of this methodology have been compared with test data for motor-operated butterfly valves in nuclear power plant. With the close review of test data and torque prediction, it is concluded that the prediction methodology is conservative to predict a required dynamic torque of motor-operated butterfly valves. In addition, the information of correct differential pressure is vital to predict a required dynamic torque of motor-operated butterfly valves
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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.
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Instantaneous flywheel torque of IC engine grey-box identification
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.
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Mechanics of torque generation in the bacterial flagellar motor.
Mandadapu, Kranthi K; Nirody, Jasmine A; Berry, Richard M; Oster, George
2015-08-11
The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well established that the passage of ions down a transmembrane gradient through the stator complex provides the energy for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify roles for two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, whereas steric forces comprise the actual "power stroke." Specifically, we propose that ion-induced conformational changes about a proline "hinge" residue in a stator α-helix are directly responsible for generating the power stroke. Our model predictions fit well with recent experiments on a single-stator motor. The proposed model provides a mechanical explanation for several fundamental properties of the flagellar motor, including torque-speed and speed-ion motive force relationships, backstepping, variation in step sizes, and the effects of key mutations in the stator.
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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.
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Production Experiences with the Cray-Enabled TORQUE Resource Manager
Energy Technology Data Exchange (ETDEWEB)
Ezell, Matthew A [ORNL; Maxwell, Don E [ORNL; Beer, David [Adaptive Computing
2013-01-01
High performance computing resources utilize batch systems to manage the user workload. Cray systems are uniquely different from typical clusters due to Cray s Application Level Placement Scheduler (ALPS). ALPS manages binary transfer, job launch and monitoring, and error handling. Batch systems require special support to integrate with ALPS using an XML protocol called BASIL. Previous versions of Adaptive Computing s TORQUE and Moab batch suite integrated with ALPS from within Moab, using PERL scripts to interface with BASIL. This would occasionally lead to problems when all the components would become unsynchronized. Version 4.1 of the TORQUE Resource Manager introduced new features that allow it to directly integrate with ALPS using BASIL. This paper describes production experiences at Oak Ridge National Laboratory using the new TORQUE software versions, as well as ongoing and future work to improve TORQUE.
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Scintigraphic presentation of hip joint synovial chondromatosis
Energy Technology Data Exchange (ETDEWEB)
Zwas, S T; Friedman, B; Nerubay, J
1988-09-01
A case of hip joint synovial chondromatosis with an unusual scintigraphic pattern is described. This pattern was suggestive of a hip joint destructive reactive articular process or late manifestations of avascular necrosis of the femoral head. Concurrent radiographs were normal, as were laboratory investigations. Follow-up radiographs six months later showed radiolucencies and erosive bone changes in the diseased joint. Surgical and histopathological findings revealed well developed hip synovial chondromatosis (HSC) with thickened synovium and large, loose, cartilaginous bodies occupying and widening the tightened joint space, with destructive secondary juxta articular pressure and bone erosions. This and other scintigraphic patterns in HSC, and the differential diagnosis of the findings in patients with painful hip presentations are discussed.
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Torque Modeling and Control of a Variable Compression Engine
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...
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Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices
Akosa, Collins Ashu; Ndiaye, Papa Birame; Manchon, Aurelien
2017-01-01
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.
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Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices
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.
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Optimal Spacecraft Attitude Control Using Aerodynamic Torques
2007-03-01
His design resembles a badminton shuttlecock and “uses passive aerodynamic drag torques to stabilize pitch and yaw” and active magnetic torque...Ravindran’s and Hughes’ ‘arrow-like’ design. Psiaki notes that “this arrow concept has been modified to become a badminton shuttlecock-type design...panels were placed to the rear of the center-of-mass, similar to a badminton shuttlecock, to provide passive stability about the pitch and yaw axes
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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 (T(peak)) on the overall performance (i.e. mean torque, T(mean)) 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, T(peak) and T(mean) as well as the Rate of EMG Rise (RER), peak EMG (EMG(peak)) and mean EMG (EMG(mean)) of the vastus lateralis were monitored for each contraction. A wavelet transform was also performed on raw EMG signal for instant mean frequency (if(mean)) calculation. A neuromuscular testing procedure was carried out before and immediately after the fatiguing protocol including evoked RTD (eRTD) and maximal evoked torque (eT(peak)) induced by high frequency doublet (100 Hz). T(mean) decrease was correlated to RTD and T(peak) decrease (R(²) = 0.62; p<0.001; respectively β=0.62 and β=0.19). RER, eRTD and initial if(mean) (0-225 ms) decreased after 20 sets (respectively -21.1 ± 14.1, -25 ± 13%, and ~20%). RTD decrease was correlated to RER decrease (R(²) = 0.36; p<0.05). The eT(peak) decreased significantly after 20 sets (24 ± 5%; p<0.05) contrary to EMG(peak) (-3.2 ± 19.5 %; p=0.71). Our results show that reductions of RTD explained part of the alterations of the overall performance during repeated moderate velocity maximal exercise. The reductions of RTD were associated to an impairment of the ability of the central nervous system to maximally activate the muscle in the first milliseconds of the contraction.
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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.
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In-field implementation of impedance-based structural health monitoring for insulated rail joints
Albakri, Mohammad I.; Malladi, V. V. N. Sriram; Woolard, Americo G.; Tarazaga, Pablo A.
2017-04-01
Track defects are a major safety concern for the railroad industry. Among different track components, insulated rail joints, which are widely used for signaling purposes, are considered a weak link in the railroad track. Several joint-related defects have been identified by the railroad community, including rail wear, torque loss, and joint bar breakage. Current track inspection techniques rely on manual and visual inspection or on specially equipped testing carts, which are costly, timeconsuming, traffic disturbing, and prone to human error. To overcome the aforementioned limitations, the feasibility of utilizing impedance-based structural health monitoring for insulated rail joints is investigated in this work. For this purpose, an insulated joint, provided by Koppers Inc., is instrumented with piezoelectric transducers and assembled with 136 AREA rail plugs. The instrumented joint is then installed and tested at the Facility for Accelerated Service Testing, Transportation Technology Center Inc. The effects of environmental and operating conditions on the measured impedance signatures are investigated through a set of experiments conducted at different temperatures and loading conditions. The capabilities of impedance-based SHM to detect several joint-related damage types are also studied by introducing reversible mechanical defects to different joint components.
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Chowdhary, Ramesh; Jimbo, Ryo; Thomsen, Christian; Carlsson, Lennart; Wennerberg, Ann
2013-03-01
To investigate the combined effect of macro and pitch shortened threads on primary and secondary stability during healing, but before dynamic loading. Two sets of turned implants with different macro geometry were prepared. The test group possessed pitch shortened threads in between the large threads and the control group did not have thread alterations. The two implant groups were placed in both femur and tibiae of 10 lop-eared rabbits, and at the time of implant insertion, insertion torques were recorded. After 4 weeks, all implants were subjected to removal torque tests. The insertion torque values for the control and test groups for the tibia were 15.7 and 20.6 Ncm, respectively, and for the femur, 11.8, and 12.8 Ncm respectively. The removal torque values for the control and test groups in the tibia were 7.9 and 9.1 Ncm, respectively, and for the femur, 7.9 and 7.7 Ncm respectively. There was no statistically significant difference between the control and test groups. Under limited dynamic load, the addition of pitch shortened threads did not significantly improve either the primary or the secondary stability of the implants in bone. © 2011 John Wiley & Sons A/S.
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Does the nervous system use equilibrium-point control to guide single and multiple joint movements?
Bizzi, E; Hogan, N; Mussa-Ivaldi, F A; Giszter, S
1992-12-01
The hypothesis that the central nervous system (CNS) generates movement as a shift of the limb's equilibrium posture has been corroborated experimentally in studies involving single- and multijoint motions. Posture may be controlled through the choice of muscle length-tension curve that set agonist-antagonist torque-angle curves determining an equilibrium position for the limb and the stiffness about the joints. Arm trajectories seem to be generated through a control signal defining a series of equilibrium postures. The equilibrium-point hypothesis drastically simplifies the requisite computations for multijoint movements and mechanical interactions with complex dynamic objects in the environment. Because the neuromuscular system is springlike, the instantaneous difference between the arm's actual position and the equilibrium position specified by the neural activity can generate the requisite torques, avoiding the complex "inverse dynamic" problem of computing the torques at the joints. The hypothesis provides a simple, unified description of posture and movement as well as contact control task performance, in which the limb must exert force stably and do work on objects in the environment. The latter is a surprisingly difficult problem, as robotic experience has shown. The prior evidence for the hypothesis came mainly from psychophysical and behavioral experiments. Our recent work has shown that microstimulation of the frog spinal cord's premotoneural network produces leg movements to various positions in the frog's motor space. The hypothesis can now be investigated in the neurophysiological machinery of the spinal cord.
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The overuse of the implant motor: effect on the output torque in overloading condition.
Lee, Du-Hyeong; Cho, Sung-Am; Lee, Cheong-Hee; Lee, Kyu-Bok
2015-06-01
The overloading of the motor affects its performance. The output torque of the implant motor under overloading condition has not been reported. The purpose of this study was to determine the reliability and the tendency of the output torque when an implant motor is consecutively used. Three implant motors were evaluated: SurgicXT/X-SG20L (NSK), INTRAsurg300/CL3-09 (KaVo), and XIP10/CRB26LX (Saeshin). The output torque was measured using an electronic torque gauge fixed with jigs. For the 40 and 50 Ncm torque settings, 300 measurements were taken at 30 rpm. Repeated measures of analysis of variance (ANOVA) and one-way ANOVA were used to compare the torque values within each group and between the groups. As repeating measures, the output torque values decreased gradually compared with the baseline. In within-group analysis, the different torque value from the first measurement appeared earliest in NSK motor, followed in order by Saeshin and KaVo motors. NSK motor showed a different torque decrease between 40 and 50 Ncm settings (p torque at the 6, 8, 9, and 10 repeat counts (p torque decreases when the surgical motor is continuously used. The NSK motor showed more significant decreases in torque than KaVo and Saeshin motors in overloading condition. © 2014 Wiley Periodicals, Inc.
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Rice, David Andrew; McNair, Peter John; Lewis, Gwyn Nancy; Dalbeth, Nicola
2015-07-28
Substantial weakness of the quadriceps muscles is typically observed in patients with arthritis. This is partly due to ongoing neural inhibition that prevents the quadriceps from being fully activated. Evidence from animal studies suggests enhanced flexion reflex excitability may contribute to this weakness. This prospective observational study examined the effects of joint aspiration and intra-articular corticosteroid injection on flexion reflex excitability, quadriceps muscle strength and knee pain in individuals with knee synovitis. Sixteen patients with chronic arthritis and clinically active synovitis of the knee participated in this study. Knee pain flexion reflex threshold, and quadriceps peak torque were measured at baseline, immediately after knee joint aspiration alone and 5 ± 2 and 15 ± 2 days after knee joint aspiration and the injection of 40 mg of methylprednisolone acetate. Compared to baseline, knee pain was significantly reduced 5 (p = 0.001) and 15 days (p = 0.009) post intervention. Flexion reflex threshold increased immediately after joint aspiration (p = 0.009) and 5 (p = 0.01) and 15 days (p = 0.002) post intervention. Quadriceps peak torque increased immediately after joint aspiration (p = 0.004) and 5 (p = 0.001) and 15 days (p knee synovitis.
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Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction
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.
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Eschler, Anica; Rösler, Klaus; Rotter, Robert; Gradl, Georg; Mittlmeier, Thomas; Gierer, Philip
2014-09-01
The classification system of Rockwood and Young is a commonly used classification for acromioclavicular joint separations subdividing types I-VI. This classification hypothesizes specific lesions to anatomical structures (acromioclavicular and coracoclavicular ligaments, capsule, attached muscles) leading to the injury. In recent literature, our understanding for anatomical correlates leading to the radiological-based Rockwood classification is questioned. The goal of this experimental-based investigation was to approve the correlation between the anatomical injury pattern and the Rockwood classification. In four human cadavers (seven shoulders), the acromioclavicular and coracoclavicular ligaments were transected stepwise. Radiological correlates were recorded (Zanca view) with 15-kg longitudinal tension applied at the wrist. The resulting acromio- and coracoclavicular distances were measured. Radiographs after acromioclavicular ligament transection showed joint space enlargement (8.6 ± 0.3 vs. 3.1 ± 0.5 mm, p acromioclavicular joint space width increased to 16.7 ± 2.7 vs. 8.6 ± 0.3 mm, p acromioclavicular joint lesions higher than Rockwood type I and II. The clinical consequence for reconstruction of low-grade injuries might be a solely surgical approach for the acromioclavicular ligaments or conservative treatment. High-grade injuries were always based on additional structural damage to the coracoclavicular ligaments. Rockwood type V lesions occurred while muscle attachments were intact.
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Pardehshenas, Hamed; Maroufi, Nader; Sanjari, Mohammad Ali; Parnianpour, Mohamad; Levin, Stephen M
2014-10-01
According to the conventional arch model of the pelvis, stability of the sacroiliac joints may require a predominance of form and force closure mechanisms: the greater the vertical shear force at the sacroiliac joints, the greater the reliance on self-bracing by horizontally or obliquely oriented muscles (such as the internal oblique). But what happens to the arch model when a person stands on one leg? In such cases, the pelvis no longer has imposts, leaving both the arch, and the arch model theory, without support. Do lumbopelvic muscle activation patterns in one-legged stances under load suggest compatibility with a different model? This study compares lumbopelvic muscle activation patterns in two-legged and one-legged stances in response to four levels of graded trunk loading in order to further our understanding the stabilization of the sacroiliac joints. Thirty male subjects experienced four levels of trunk loading (0%, 5%, 10% and 15% of body weight) by holding a bucket at one side, at three conditions: 1) two-legged standing with the bucket in the dominant hand, 2) ipsilateral loading: one-legged standing with the bucket in the dominant hand while using the same-side leg, and 3) contralateral loading: one-legged standing using the same leg used in condition 2, but with the bucket in the non-dominant hand. During these tasks, EMG signals from eight lumbopelvic muscles were collected. ANOVA with repeated design was performed on normalized EMG's to test the main effect of load and condition, and interaction effects of load by condition. Latissimus dorsi and erector spinae muscles showed an antagonistic pattern of activity toward the direction of load which may suggest these muscles as lateral trunk stabilizers. Internal oblique muscles showed a co-activation pattern with increasing task demand, which may function to increase lumbopelvic stability (P sacroiliac joint dysfunctions must be taken into consideration. Our hypothetical model may initiate thinking and
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Torque expression of 0.018 and 0.022 inch conventional brackets
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.
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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.
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Magnetic torque transferring study for bulk High-Tc superconductors and permanent magnets
International Nuclear Information System (INIS)
Wongsatanawarid, A; Suzuki, A; Seki, H; Murakami, M
2009-01-01
The torque transferring mechanism taking place in a superconducting mixer design has been studied. Several coupling magnetic arrangements were investigated for more details in the engineering design. A bulk superconductor sample was used to study the torque forces for various cooling gaps, and the twist angle dependence was also monitored for the rotational stiffness in stability. The experimental data with four permanent magnet configurations have been studied in the present work. The maximum torque forces are summarized for usage of engineering design with various gaps. The torque/gap characteristics for four configurations were also measured for the optimisation of the torque at a designed operating gap.
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Intraband and interband spin-orbit torques in noncentrosymmetric ferromagnets
Li, Hang; Gao, H.; Zâ rbo, Liviu P.; Vý borný , K.; Wang, Xuhui; Garate, Ion; Dogan, Fatih; Čejchan, A.; Sinova, Jairo; Jungwirth, T.; Manchon, Aurelien
2015-01-01
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.
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Knudsen torque: A rotational mechanism driven by thermal force
Li, Qi; Liang, Tengfei; Ye, Wenjing
2014-09-01
Thermally induced mechanical loading has been shown to have significant effects on micro- and nano-objects immersed in a gas with a nonuniform 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. Our study has found that a torque can be induced if the configuration of the system is asymmetric. In addition, both the magnitude and the direction of the torque depend highly on the system configuration, indicating the possibility of manipulating the rotational motion via geometrical design. Based on this feature, two types of rotational micromotor that are of practical importance, namely pendulum motor and unidirectional motor, are designed. The magnitude of the torque at Kn =0.5 can reach to around 2nN×μm for a rectangular microbeam with a length of 100μm.
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Intraband and interband spin-orbit torques in noncentrosymmetric ferromagnets
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.
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Torque fluctuations caused by upstream mean flow and turbulence
Farr, T. D.; Hancock, P. E.
2014-12-01
A series of studies are in progress investigating the effects of turbine-array-wake interactions for a range of atmospheric boundary layer states by means of the EnFlo meteorological wind tunnel. The small, three-blade model wind turbines drive 4-quadrant motor-generators. Only a single turbine in neutral flow is considered here. The motor-generator current can be measured with adequate sensitivity by means of a current sensor allowing the mean and fluctuating torque to be inferred. Spectra of torque fluctuations and streamwise velocity fluctuations ahead of the rotor, between 0.1 and 2 diameters, show that only the large-scale turbulent motions contribute significantly to the torque fluctuations. Time-lagged cross-correlation between upstream velocity and torque fluctuations are largest over the inner part of the blade. They also show the turbulence to be frozen in behaviour over the 2 diameters upstream of the turbine.
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Nakamura, Y.; Nishikawa, M.; Osawa, H.; Okamoto, Y.; Kanao, T.; Sato, R.
2018-05-01
In this article, we propose the detection method of the recorded data pattern by the envelope of the temporal magnetization dynamics of resonantly interacting spin-torque oscillator on the microwave assisted magnetic recording for three-dimensional magnetic recording. We simulate the envelope of the waveform from recorded dots with the staggered magnetization configuration, which are calculated by using a micromagnetic simulation. We study the data detection methods for the envelope and propose a soft-output Viterbi algorithm (SOVA) for partial response (PR) system as a signal processing system for three dimensional magnetic recording.
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Torque loss of different abutment sizes before and after cyclic loading.
Moris, Izabela Cristina; Faria, Adriana Cláudia; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina
2015-01-01
The aim of this study was to compare 3.8- and 4.8-mm abutments submitted to simulations of masticatory cycles to examine whether abutment diameter and cemented vs screw-retained crowns affect torque loss of the abutments and crowns. Forty implant/abutment sets were divided into the following groups (n = 10 in each group): (1) G4.8S included 4.8-mm abutment with screw-retained crown; (2) G4.8C included 4.8-mm abutment with cemented crown; (3) G3.8S included 3.8-mm abutment with screw-retained crown; and (4) G3.8C included 3.8-mm abutment with cemented crown. All abutments were tightened with torque values of 20 Ncm, and 10 Ncm for screw-retained crowns. Torque loss was measured before and after cycling loading (300,000 cycles). Torque loss of screw-retained crowns significantly increased after cycling in abutments of groups G3.8S (P ≤ .05) and G4.8S (P = .001). No difference was noted between the abutments before cycling (P = .735), but G3.8S abutments presented greater torque loss than the other groups after cycling (P = .008). Significant differences were noted in the abutment torque loss before and after cycling loading only for the G3.8C group (P ≤ .05). The abutment diameter affects torque loss of screw-retained crowns and leads to failure during the test; mechanical cycling increases torque loss of abutment screw and screw-retained crowns.
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Hasan, Z; Enoka, R M
1985-01-01
Since the moment arms for the elbow-flexor muscles are longest at intermediate positions of the elbow and shorter at the extremes of the range of motion, it was expected that the elbow torque would also show a peak at an intermediate angle provided the activity of the flexor muscles remained constant. We measured the isometric elbow torque at different elbow angles while the subject attempted to keep constant the electromyographic activity (EMG) of the brachioradialis muscle. The torque-angle relationship thus obtained exhibited a peak, as expected, but the shape of the relationship varied widely among subjects. This was due in part to differences in the variation of the biceps brachii EMG with elbow angle among the different subjects. The implications of these observations for the equilibrium-point hypothesis of movement were investigated as follows. The subject performed elbow movements in the presence of an external torque (which tended to extend the elbow joint) provided by a weight-and-pulley arrangement. We found in the case of flexion movements that invariably there was a transient increase in flexor EMG, as would seem necessary for initiating the movement. However, the steady-state EMG after the movement could be greater or less than the pre-movement EMG. Specifically, the least flexor EMG was required for equilibrium in the intermediate range of elbow angles, compared to the extremes of the range of motion. The EMG-angle relationship, however, varied with the muscle and the subject. The observation that the directions of change in the transient and the steady-state EMG are independent of each other militates against the generality of the equilibrium-point hypothesis. However, a form of the hypothesis which includes the effects of the stretch reflex is not contradicted by this observation.
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Analytical calculation of the torque exerted between two perpendicularly magnetized magnets
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.
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A flight simulator control system using electric torque motors
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.
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Shielding of External Magnetic Perturbations By Torque In Rotating Tokamak Plasmas
International Nuclear Information System (INIS)
Park, Jong-Kyu; Boozer, Allen H.; Menard, Jonathan E.; Gerhardt, Stefan P.; Sabbagh, Steve A.
2009-01-01
The imposition of a nonaxisymmetric magnetic perturbation on a rotating tokamak plasma requires energy and toroidal torque. Fundamental electrodynamics implies that the torque is essentially limited and must be consistent with the external response of a plasma equilibrium (rvec f) = (rvec j) x (rvec B). Here magnetic measurements on National Spherical Torus eXperiment (NSTX) device are used to derive the energy and the torque, and these empirical evaluations are compared with theoretical calculations based on perturbed scalar pressure equilibria (rvec f) = (rvec (del))p coupled with the theory of nonambipolar transport. The measurement and the theory are consistent within acceptable uncertainties, but can be largely inconsistent when the torque is comparable to the energy. This is expected since the currents associated with the torque are ignored in scalar pressure equilibria, but these currents tend to shield the perturbation.
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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...
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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.
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Diagnosis of Thermal Efficiency of Nuclear Power Plants Using Optical Torque Sensors
International Nuclear Information System (INIS)
Shuichi Umezawa; Jun Adachi
2006-01-01
A new optical torque measuring method was applied to diagnosis of thermal efficiency of nuclear power plants. The sensor allows torque deformation of the rotor caused by power transmission to be measured without contact. Semiconductor laser beams and small pieces of stainless reflector that have bar-code patterns are employed. The intensity of the reflected laser beam is measured and then input into a computer through an APD and an A/D converter having high frequency sampling rates. The correlation analysis technique can translate these data into the torque deformation angle. This angle allows us to obtain the turbine output along with the torsional rigidity and the rotating speed of the rotor. The sensor was applied to a nuclear plant of Tokyo Electric Power Company, TEPCO, following its application success to the early combined cycle plants and the advanced combined cycle plants of TEPCO. As the turbine rotor of the nuclear power plant is less exposed than that of the combined cycle plants, the measurement position is confined to a narrow gap. In order to overcome the difficulty in installation, the shape of the sensor is modified to be long and thin. Sensor performance of the nuclear power plant was inspected over a year. The value of the torsional rigidity was analyzed by the finite element method at first. Accuracy was improved by correcting the torsional rigidity so that the value was consistent with the generator output. As a result, it is considered that the sensor performance has reached a practical use level. (authors)
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Inverse Dynamics Model for the Ankle Joint with Applications in Tibia Malleolus Fracture
Budescu, E.; Merticaru, E.; Chirazi, M.
The paper presents a biomechanical model of the ankle joint, in order to determine the force and the torque of reaction into the articulation, through inverse dynamic analysis, in various stages of the gait. Thus, knowing the acceleration of the foot and the reaction force between foot and ground during the gait, determined by experimental measurement, there was calculated, for five different positions of the foot, the joint reaction forces, on the basis of dynamic balance equations. The values numerically determined were compared with the admissible forces appearing in the technical systems of osteosynthesis of tibia malleolus fracture, in order to emphasize the motion restrictions during bone healing.
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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.
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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.
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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...
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RFID Torque Sensing Tag System for Fasteners
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.
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Compensation of an attitude disturbance torque caused by magnetic substances in LEO satellites
Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki
This research considers an attitude disturbance torque caused by ferromagnetic substances in a LEO satellite. In most LEO satellite missions, a gravity gradient torque, solar pressure torque, aerodynamic torque, and magnetic dipole moment torque are considered for their attitude control systems, however, the effect of the ferromagnetic substances causing a disturbance torque in the geomagnetic field is not considered in previous satellite missions. The ferromagnetic substances such as iron cores of MTQs and a magnetic hysteresis damper for a passive attitude control system are used in various small satellites. These substances cause a disturbance torque which is almost the same magnitude of the dipole magnetic disturbance and the dominant disturbance in the worst cases. This research proposes a method to estimate and compensate for the effect of the ferromagnetic substances using an extended Kalman filter. From simulation results, the research concludes that the proposed method is useful and attractive for precise attitude control for LEO satellite missions.
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Mode coupling in spin torque oscillators
International Nuclear Information System (INIS)
Zhang, Steven S.-L.; Zhou, Yan; Li, Dong; Heinonen, Olle
2016-01-01
A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.
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Mode coupling in spin torque oscillators
Energy Technology Data Exchange (ETDEWEB)
Zhang, Steven S.-L., E-mail: ZhangShule@missouri.edu [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Zhou, Yan, E-mail: yanzhou@hku.hk [Department of Physics, The University of Hong Kong, Hong Kong (China); Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong (China); Li, Dong, E-mail: geodesic.ld@gmail.com [Department of Physics, Centre for Nonlinear Studies, and Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Heinonen, Olle, E-mail: heinonen@anl.gov [Material Science Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Northwestern-Argonne Institute of Science and Technology, 2145 Sheridan Road, Evanston, IL 60208 (United States); Computation Institute, The Unversity of Chicago, 5735 S Ellis Avenue, Chicago, IL 60637 (United States)
2016-09-15
A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.
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Two-Finger Tightness: What Is It? Measuring Torque and Reproducibility in a Simulated Model.
Acker, William B; Tai, Bruce L; Belmont, Barry; Shih, Albert J; Irwin, Todd A; Holmes, James R
2016-05-01
Residents in training are often directed to insert screws using "two-finger tightness" to impart adequate torque but minimize the chance of a screw stripping in bone. This study seeks to quantify and describe two-finger tightness and to assess the variability of its application by residents in training. Cortical bone was simulated using a polyurethane foam block (30-pcf density) that was prepared with predrilled holes for tightening 3.5 × 14-mm long cortical screws and mounted to a custom-built apparatus on a load cell to capture torque data. Thirty-three residents in training, ranging from the first through fifth years of residency, along with 8 staff members, were directed to tighten 6 screws to two-finger tightness in the test block, and peak torque values were recorded. The participants were blinded to their torque values. Stripping torque (2.73 ± 0.56 N·m) was determined from 36 trials and served as a threshold for failed screw placement. The average torques varied substantially with regard to absolute torque values, thus poorly defining two-finger tightness. Junior residents less consistently reproduced torque compared with other groups (0.29 and 0.32, respectively). These data quantify absolute values of two-finger tightness but demonstrate considerable variability in absolute torque values, percentage of stripping torque, and ability to consistently reproduce given torque levels. Increased years in training are weakly correlated with reproducibility, but experience does not seem to affect absolute torque levels. These results question the usefulness of two-finger tightness as a teaching tool and highlight the need for improvement in resident motor skill training and development within a teaching curriculum. Torque measuring devices may be a useful simulation tools for this purpose.
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Spin-orbit torque in two-dimensional antiferromagnetic topological insulators
Ghosh, Sumit; Manchon, Aurelien
2017-01-01
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.
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Spin-orbit torque in two-dimensional antiferromagnetic topological insulators
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.
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Latash, M L; Gottlieb, G L
1991-09-01
We describe a model for the regulation of fast, single-joint movements, based on the equilibrium-point hypothesis. Limb movement follows constant rate shifts of independently regulated neuromuscular variables. The independently regulated variables are tentatively identified as thresholds of a length sensitive reflex for each of the participating muscles. We use the model to predict EMG patterns associated with changes in the conditions of movement execution, specifically, changes in movement times, velocities, amplitudes, and moments of limb inertia. The approach provides a theoretical neural framework for the dual-strategy hypothesis, which considers certain movements to be results of one of two basic, speed-sensitive or speed-insensitive strategies. This model is advanced as an alternative to pattern-imposing models based on explicit regulation of timing and amplitudes of signals that are explicitly manifest in the EMG patterns.
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Spin transfer torque with spin diffusion in magnetic tunnel junctions
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.
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Effect of Different Torque Settings on Crack Formation in Root Dentin.
Dane, Asım; Capar, Ismail Davut; Arslan, Hakan; Akçay, Merve; Uysal, Banu
2016-02-01
The aim of the present study was to observe the incidence of cracks in root canal dentin using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland) at low- and high-torque settings. Sixty-nine mandibular premolar teeth that had been extracted for different reasons were selected. The teeth were divided into 3 groups: an unprepared control group, a low-torque settings group (SX = 3, S1 = 2, S2 = 1, F1 = 1.5, F2 = 2, F3 = 2, F4 = 2 N/cm), and a high-torque settings group (SX = 4, S1 = 4, S2 = 1.5, F1 = 2, F2 = 3, F3 = 3, F4 = 3 N/cm). After a root canal procedure, all the teeth were horizontally sectioned at 2, 4, 6, and 8 mm from the apex. Then, under a stereomicroscope, all the slices were examined to determine the presence of cracks. A chi-square test was used for data analysis. The significance level was set at P = .05. There were no cracks in the unprepared control group. Vertical root fractures were not observed in any of the groups. There were significantly fewer cracks (17.4% of the sections) in the low-torque group than in the high-torque group (29.4% of the sections) (P torque than at low-torque settings. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
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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.
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International Nuclear Information System (INIS)
Herda, Trent J; Ryan, Eric D; Costa, Pablo B; DeFreitas, Jason M; Walter, Ashley A; Stout, Jeffrey R; Beck, Travis W; Cramer, Joel T; Housh, Terry J; Weir, Joseph P
2009-01-01
The primary purpose of this study was to examine the consistency of ordinary least-squares (OLS) and generalized least-squares (GLS) polynomial regression analyses utilizing linear, quadratic and cubic models on either five or ten data points that characterize the mechanomyographic amplitude (MMG RMS ) versus isometric torque relationship. The secondary purpose was to examine the consistency of OLS and GLS polynomial regression utilizing only linear and quadratic models (excluding cubic responses) on either ten or five data points. Eighteen participants (mean ± SD age = 24 ± 4 yr) completed ten randomly ordered isometric step muscle actions from 5% to 95% of the maximal voluntary contraction (MVC) of the right leg extensors during three separate trials. MMG RMS was recorded from the vastus lateralis during the MVCs and each submaximal muscle action. MMG RMS versus torque relationships were analyzed on a subject-by-subject basis using OLS and GLS polynomial regression. When using ten data points, only 33% and 27% of the subjects were fitted with the same model (utilizing linear, quadratic and cubic models) across all three trials for OLS and GLS, respectively. After eliminating the cubic model, there was an increase to 55% of the subjects being fitted with the same model across all trials for both OLS and GLS regression. Using only five data points (instead of ten data points), 55% of the subjects were fitted with the same model across all trials for OLS and GLS regression. Overall, OLS and GLS polynomial regression models were only able to consistently describe the torque-related patterns of response for MMG RMS in 27–55% of the subjects across three trials. Future studies should examine alternative methods for improving the consistency and reliability of the patterns of response for the MMG RMS versus isometric torque relationship
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Sasaki, Eiji; Sasaki, Shizuka; Chiba, Daisuke; Yamamoto, Yuji; Nawata, Atsushi; Tsuda, Eiichi; Nakaji, Shigeyuki; Ishibashi, Yasuyuki
2018-01-01
Trunk muscle weakness and imbalance are risk factors for postural instability, low back pain, and poor postoperative outcomes. The association between trunk muscle strength and aging is poorly understood, and establishing normal reference values is difficult. We aimed to establish the validity of a novel portable trunk muscle torque measurement instrument (PTMI). We then estimated reference data for healthy young adults and elucidated age-related weakness in trunk muscle strength. Twenty-four university students were enrolled to validate values for PTMI, and 816 volunteers from the general population who were recruited to the Iwaki Health Promotion Project were included to estimate reference data for trunk muscle strength. Trunk flexion and extension torque were measured with PTMI and KinCom, and interclass correlation coefficients (ICC) were estimated to evaluate the reliability of PTMI values. Furthermore, from the young adult reference, the age-related reduction in trunk muscle torque and the prevalence of sarcopenia among age-sex groups were estimated. The ICC in flexion and extension torque were 0.807 (psarcopenia increased with age, and the prevalence due to flexion torque was double that of extension torque. Flexion torque decreased significantly after 60 years of age, and extension torque decreased after 70 years of age. In males over age 80, trunk muscle torque decreased to 49.1% in flexion and 63.5% in extension. In females over age 80, trunk muscle torque decreased to 60.7% in flexion and 68.4% in extension. The validity of PTMI was confirmed by correlation with KinCom. PTMI produced reference data for healthy young adults, and demonstrated age-related reduction in trunk muscle torque. Trunk sarcopenia progressed with aging, and the loss of flexion torque began earlier than extension torque. At age 80, trunk muscle torque had decreased 60% compared with healthy young adults.
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Steady flow torques in a servo motor operated rotary directional control valve
International Nuclear Information System (INIS)
Wang, He; Gong, Guofang; Zhou, Hongbin; Wang, Wei
2016-01-01
Highlights: • A novel servo motor operated rotary directional control valve is proposed. • Steady flow torque is a crucial issue that affects rotary valve performance. • Steady flow torque is analyzed on the aspects of theory, simulation and experiment. • Change law of the steady flow torque with spool rotation angle is explored. • Effect of pressure drop and flow rate on the steady flow torque is studied. - Abstract: In this paper, a servo motor operated rotary directional control valve is proposed, and a systematic analysis of steady flow torques in this valve is provided by theoretical calculation, CFD simulation and experimental test. In the analysis, spool rotation angle corresponding to the maximum orifice opening is tagged as 0°. Over a complete change cycle of the orifice, the range of spool rotation angle is symmetric about 0°. The results show that the direction of steady flow torques in this valve is always the direction of orifice closing. The steady flow torques serve as resistances to the spool rotation when the orifice opening increases, while impetuses to the spool rotation when the orifice opening decreases. At a certain pressure drop or flow rate, steady flow torques are approximately equal and opposite when at spool rotation angles which are symmetric about 0°. When the spool rotates from 0°, at a certain pressure drop, their values increase first then decrease with the spool rotation and reach their maximum values at an angle corresponding to about 1/2 of the maximum orifice opening, and at a certain flow rate, their values increase with the spool rotation. The steady flow torques in this valve are the sums of those in the meter-in and meter-out valve chambers. At a certain spool rotation angle, steady flow torques in the meter-in and meter-out valve chambers are approximately proportional to the pressure drop and the second power of the flow rate through the orifice. Theoretical calculation and CFD simulation can be validated by
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DEFF Research Database (Denmark)
Mantica, P.; Tala, T.; Ferreira, J.S.
2010-01-01
Perturbative experiments have been carried out in the Joint European Torus [Fusion Sci. Technol. 53(4) (2008)] in order to identify the diffusive and convective components of toroidal momentum transport. The torque source was modulated either by modulating tangential neutral beam power...... or by modulating in antiphase tangential and normal beams to produce a torque perturbation in the absence of a power perturbation. The resulting periodic perturbation in the toroidal rotation velocity was modeled using time-dependent transport simulations in order to extract empirical profiles of momentum...
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THREE-DIMENSIONAL DISK-PLANET TORQUES IN A LOCALLY ISOTHERMAL DISK
International Nuclear Information System (INIS)
D'Angelo, Gennaro; Lubow, Stephen H.
2010-01-01
We determine an expression for the Type I planet migration torque involving a locally isothermal disk, with moderate turbulent viscosity (5 x 10 -4 ∼< α ∼< 0.05), based on three-dimensional nonlinear hydrodynamical simulations. The radial gradients (in a dimensionless logarithmic form) of density and temperature are assumed to be constant near the planet. We find that the torque is roughly equally sensitive to the surface density and temperature radial gradients. Both gradients contribute to inward migration when they are negative. Our results indicate that two-dimensional calculations with a smoothed planet potential, used to account for the effects of the third dimension, do not accurately determine the effects of density and temperature gradients on the three-dimensional torque. The results suggest that substantially slowing or stopping planet migration by means of changes in disk opacity or shadowing is difficult and appears unlikely for a disk that is locally isothermal. The scalings of the torque and torque density with planet mass and gas sound speed follow the expectations of linear theory. We also determine an improved formula for the torque density distribution that can be used in one-dimensional long-term evolution studies of planets embedded in locally isothermal disks. This formula can be also applied in the presence of mildly varying radial gradients and of planets that open gaps. We illustrate its use in the case of migrating super-Earths and determine some conditions sufficient for survival.
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Universal adaptive torque control for PM motors for field-weakening region operation
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.
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On the monoaxial stabilization of a rigid body under vanishing restoring torque
Aleksandrov, A. Yu.; Aleksandrova, E. B.; Tikhonov, A. A.
2018-05-01
The problem of monoaxial stabilization of a rigid body is studied. It is assumed that a linear time-invariant dissipative torque and a time-varying restoring torque vanishing as time increases act on the body. Both the case of linear restoring torque and that of essentially nonlinear one are considered. With the aid of the decomposition method, conditions are obtained under which we can guarantee the asymptotic stability of an equilibrium position of the body despite the vanishing of the restoring torque. A numerical simulation is provided to demonstrate the effectiveness of our theoretical results.
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DEFF Research Database (Denmark)
Jensen, Bente Rona; Olesen, Annesofie T.; Pedersen, Mogens Theisen
2013-01-01
Introduction: We investigated muscle activation strategy and performance of knee extensor and flexor muscles in children and adults with generalized joint hypermobility (GJH) and compared them with controls. Methods: Muscle activation, torque steadiness, electromechanical delay, and muscle strength...... were evaluated in 39 children and 36 adults during isometric knee extension and flexion. Subjects performed isometric maximum contractions, submaximal contractions at 25% maximum voluntary contraction (MVC), and explosive contractions. Results: Agonist activation was reduced, and coactivation ratio...... was greater in GJH during knee flexion compared with controls. Torque steadiness was impaired in adults with GJH during knee flexion. No effect of GJH was found on muscle strength or electromechanical delay. Correlation analysis revealed an association between GJH severity and function in adults. Conclusions...
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Železný , J.; Gao, H.; Manchon, Aurelien; Freimuth, Frank; Mokrousov, Yuriy; Zemen, J.; Mašek, J.; Sinova, Jairo; Jungwirth, T.
2017-01-01
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.
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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.
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Computations of Torque-Balanced Coaxial Rotor Flows
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.
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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.
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Shot noise of spin current and spin transfer torque
Yu, Yunjin; Zhan, Hongxin; Wan, Langhui; Wang, Bin; Wei, Yadong; Sun, Qingfeng; Wang, Jian
2013-04-01
We report the theoretical investigation of the shot noise of the spin current (Sσ) and the spin transfer torque (Sτ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear Sσ - V and Sτ - V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage Nτ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque Nτ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period Nτ(θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters.
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Current control of PMSM based on maximum torque control reference frame
Ohnuma, Takumi
2017-07-01
This study presents a new method of current controls of PMSMs (Permanent Magnet Synchronous Motors) based on a maximum torque control reference frame, which is suitable for high-performance controls of the PMSMs. As the issues of environment and energy increase seriously, PMSMs, one of the AC motors, are becoming popular because of their high-efficiency and high-torque density in various applications, such as electric vehicles, trains, industrial machines, and home appliances. To use the PMSMs efficiently, a proper current control of the PMSMs is necessary. In general, a rotational coordinate system synchronizing with the rotor is used for the current control of PMSMs. In the rotating reference frame, the current control is easier because the currents on the rotating reference frame can be expressed as a direct current in the controller. On the other hand, the torque characteristics of PMSMs are non-linear and complex; the PMSMs are efficient and high-density though. Therefore, a complicated control system is required to involve the relation between the torque and the current, even though the rotating reference frame is adopted. The maximum torque control reference frame provides a simpler way to control efficiently the currents taking the torque characteristics of the PMSMs into consideration.
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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 ...
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Role of external torque in the formation of ion thermal internal transport barriers
Jhang, Hogun; Kim, S. S.; Diamond, P. H.
2012-04-01
We present an analytic study of the impact of external torque on the formation of ion internal transport barriers (ITBs). A simple analytic relation representing the effect of low external torque on transport bifurcations is derived based on a two field transport model of pressure and toroidal momentum density. It is found that the application of an external torque can either facilitate or hamper bifurcation in heat flux driven plasmas depending on its sign relative to the direction of intrinsic torque. The ratio between radially integrated momentum (i.e., external torque) density to power input is shown to be a key macroscopic control parameter governing the characteristics of bifurcation.
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Spin transfer torque with spin diffusion in magnetic tunnel junctions
Manchon, Aurelien; Matsumoto, R.; Jaffres, H.; Grollier, J.
2012-01-01
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
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Spin Hall effect-driven spin torque in magnetic textures
Manchon, Aurelien; Lee, K.-J.
2011-01-01
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.
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Spin Hall effect-driven spin torque in magnetic textures
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.
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Engine Torque Control of Spark Ignition Engine using Fuzzy Gain Scheduling
Aris Triwiyatno
2012-01-01
In the spark ignition engine system, driver convenience is very dependent on satisfying engine torque appropriate with the throttle position given by the driver. Unfortunately, sometimes the fulfillment of engine torque is not in line with fuel saving efforts. This requires the development of high performance and robust power train controllers. One way to potentially meet these performance requirements is to introduce a method of controlling engine torque using fuzzy gain scheduling. By using...
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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
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Thermomagnetic torques in polyatomic gases
Hildebrandt, A. F.; Wood, C. T.
1972-01-01
The application of the Scott effect to the dynamics of galactic and stellar rotation is investigated. Efforts were also made to improve the sensitivity and stability of torque measurements and understand the microscopic mechanism that causes the Scott effect.
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Optimum geometry for torque ripple minimization of switched reluctance motors
Sahin, F.; Ertan, H.B.; Leblebicioglu, K.
2000-01-01
For switched reluctance motors, one of the major problems is torque ripple which causes increased undesirable acoustic noise and possibly speed ripple. This paper describes an approach to determine optimum magnetic circuit parameters to minimize low speed torque ripple for such motors. The
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Directory of Open Access Journals (Sweden)
Eiji Sasaki
Full Text Available Trunk muscle weakness and imbalance are risk factors for postural instability, low back pain, and poor postoperative outcomes. The association between trunk muscle strength and aging is poorly understood, and establishing normal reference values is difficult. We aimed to establish the validity of a novel portable trunk muscle torque measurement instrument (PTMI. We then estimated reference data for healthy young adults and elucidated age-related weakness in trunk muscle strength. Twenty-four university students were enrolled to validate values for PTMI, and 816 volunteers from the general population who were recruited to the Iwaki Health Promotion Project were included to estimate reference data for trunk muscle strength. Trunk flexion and extension torque were measured with PTMI and KinCom, and interclass correlation coefficients (ICC were estimated to evaluate the reliability of PTMI values. Furthermore, from the young adult reference, the age-related reduction in trunk muscle torque and the prevalence of sarcopenia among age-sex groups were estimated. The ICC in flexion and extension torque were 0.807 (p<0.001 and 0.789 (p<0.001, respectively. The prevalence of sarcopenia increased with age, and the prevalence due to flexion torque was double that of extension torque. Flexion torque decreased significantly after 60 years of age, and extension torque decreased after 70 years of age. In males over age 80, trunk muscle torque decreased to 49.1% in flexion and 63.5% in extension. In females over age 80, trunk muscle torque decreased to 60.7% in flexion and 68.4% in extension. The validity of PTMI was confirmed by correlation with KinCom. PTMI produced reference data for healthy young adults, and demonstrated age-related reduction in trunk muscle torque. Trunk sarcopenia progressed with aging, and the loss of flexion torque began earlier than extension torque. At age 80, trunk muscle torque had decreased 60% compared with healthy young adults.
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Model analysis and experimental investigation of the friction torque during the CMP process
International Nuclear Information System (INIS)
Guo Dongming; Xu Chi; Kang Renke; Jin Zhuji
2011-01-01
A model for calculating friction torque during the chemical mechanical polishing (CMP) process is presented, and the friction force and torque detection experiments during the CMP process are carried out to verify the model. The results show that the model can well describe the feature of friction torque during CMP processing. The research results provide a theoretical foundation for the CMP endpoint detection method based on the change of the torque of the polishing head rotational spindle. (semiconductor technology)
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Torque Split Strategy for Parallel Hybrid Electric Vehicles with an Integrated Starter Generator
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...
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Torques Induced by Scattered Pebble-flow in Protoplanetary Disks
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.
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International Nuclear Information System (INIS)
Mizuno, Koichi; Shinomiya, Kenichi; Otani, Kazuyuki
2005-01-01
The correlation between the insertion torque of a lumbar pedicle screw and the mechanical stability of the screw in the bone has been mentioned in in vitro studies. The purpose of this study was to confirm the factors affecting the insertion torque of such screws in vivo. Also, the contribution of insertion torque to the initial stability of the fusion area was to be analyzed in vivo. A series of 23 cases representing 50 lumbar vertebrae were included in this study, in which we examined bone mineral density using quantitative computed tomography (CT) prior to operation. Two screw shapes were utilized, with the insertion torque for each screw measured at two points in time. The correlation between insertion torque and mineral density was investigated. Screw positions were confirmed on postoperative CT scans, and the effect of the screw thread cutting into the cortex bone was investigated. Radiographic changes at three points during a period of 3 months were also measured, and we then evaluated the interrelations between these changes and insertion torque. Furthermore, the relation between insertion torque and instability at 3 months was investigated. Correlations of insertion torque and bone mineral density depended on screw shape. There was no correlation found with mineral density in the case of cylindrical screws. Insertion torque was not affected by the screw thread cutting into the cortex of bone. As for postoperative alignment changes, no definitive trends could be ascertained, and no interrelations with torque and alignment changes were observed. There is a possibility that insertion torque was related to early-stage stability, but no statistical relation could be determined. (author)
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A Study on the Propulsive Mechanism of a Double Jointed Fish Robot Utilizing Self-Excitation Control
Nakashima, Motomu; Ohgishi, Norifumi; Ono, Kyosuke
This paper describes a numerical and experimental study of a double jointed fish robot utilizing self-excitation control. The fish robot is composed of a streamlined body and a rectangular caudal fin. The body length is 280mm and it has a DC motor to actuate its first joint and a potentiometer to detect the angle of its second joint. The signal from the potentiometer is fed back into the DC motor, so that the system can be self-excited. In order to obtain a stable oscillation and a resultant stable propulsion, a torque limiter circuit is employed. From the experiment, it has been found that the robot can stably propel using this control and the maximum propulsive speed is 0.42m/s.
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Spin-orbit-coupled transport and spin torque in a ferromagnetic heterostructure
Wang, Xuhui; Ortiz Pauyac, Christian; Manchon, Aurelien
2014-01-01
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.
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Spin-orbit-coupled transport and spin torque in a ferromagnetic heterostructure
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.
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Current-induced spin transfer torque in ferromagnet-marginal Fermi liquid double tunnel junctions
International Nuclear Information System (INIS)
Mu Haifeng; Zheng Qingrong; Jin Biao; Su Gang
2005-01-01
Current-induced spin transfer torque through a marginal Fermi liquid (MFL) which is connected to two noncollinearly aligned ferromagnets via tunnel junctions is discussed in terms of the nonequilibrium Green function method. It is found that in the absence of the spin-flip scattering, the magnitude of the torque increases with the polarization and the coupling constant λ of the MFL, whose maximum increases with λ linearly, showing that the interactions between electrons tend to enhance the spin torque. When the spin-flip scattering is included, an additional spin torque is induced. It is found that the spin-flip scattering enhances the spin torque and gives rise to a nonlinear angular shift
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Torque for electron spin induced by electron permanent electric dipole moment
Energy Technology Data Exchange (ETDEWEB)
Senami, Masato, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp; Fukuda, Masahiro, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp; Ogiso, Yoji, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp; Tachibana, Akitomo, E-mail: senami@me.kyoto-u.ac.jp, E-mail: akitomo@scl.kyoto-u.ac.jp [Department of Micro Engineering, Kyoto University, Kyoto 615-8540 (Japan)
2014-10-06
The spin torque of the electron is studied in relation to the electric dipole moment (EDM) of the electron. The spin dynamics is known to be given by the spin torque and the zeta force in quantum field theory. The effect of the EDM on the torque of the spin brings a new term in the equation of motion of the spin. We study this effect for a solution of the Dirac equation with electromagnetic field.
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Improvement in torque and power transmission system of Savonius wind turbine
Energy Technology Data Exchange (ETDEWEB)
Ghosh, K.; Kumar, A.; Gupta, S. [Indian Inst. of Technology, Kanpur (India). Aerospace Engineering Dept.
2006-07-01
The Savonius vertical axis wind turbine has a simple geometry and is inexpensive to build due to its high power coefficient. However, because its torque coefficient varies widely with wind angles and even becomes negative twice in a revolution, it has not been widely commercialized. A Savonius rotor is conventionally built in 2 or 3 tiers, with 90-degree or 60-degree stagger between tiers for smoother torque. The torque coefficient versus wind angle data for multi-tier rotors can be generated by overlapping single-tier data with requisite stagger. This process ignores aerodynamic interference between tiers. The torque coefficient versus wind angle was measured in static mode and the power coefficient was measured in rotating mode of a 2-tier Savonius using a wind tunnel technique involving the brake-dynamometer principle and wind tunnel balance. A significant aerodynamic interference and lower power coefficient were observed. Static and dynamic testing procedures were described and smoke flow models and visualization were also presented. Subsequently, a discussion of the results of the testing were presented. It was concluded that there is significant aerodynamic interference between the tiers of a 2-tier model leading to reduced values of torque and power. Modification of the Savonius wind turbine by adding 20 per cent thick symmetrical airfoils results in improved torque, without significantly increasing average wake width. 3 refs., 1 tab., 13 refs.
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Vision system for dial gage torque wrench calibration
Aggarwal, Neelam; Doiron, Theodore D.; Sanghera, Paramjeet S.
1993-11-01
In this paper, we present the development of a fast and robust vision system which, in conjunction with the Dial Gage Calibration system developed by AKO Inc., will be used by the U.S. Army in calibrating dial gage torque wrenches. The vision system detects the change in the angular position of the dial pointer in a dial gage. The angular change is proportional to the applied torque. The input to the system is a sequence of images of the torque wrench dial gage taken at different dial pointer positions. The system then reports the angular difference between the different positions. The primary components of this vision system include modules for image acquisition, linear feature extraction and angle measurements. For each of these modules, several techniques were evaluated and the most applicable one was selected. This system has numerous other applications like vision systems to read and calibrate analog instruments.
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Spin-transfer torque generated by a topological insulator
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.
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Inertial torque during reaching directly impacts grip-force adaptation to weightless objects.
Giard, T; Crevecoeur, F; McIntyre, J; Thonnard, J-L; Lefèvre, P
2015-11-01
A hallmark of movement control expressed by healthy humans is the ability to gradually improve motor performance through learning. In the context of object manipulation, previous work has shown that the presence of a torque load has a direct impact on grip-force control, characterized by a significantly slower grip-force adjustment across lifting movements. The origin of this slower adaptation rate remains unclear. On the one hand, information about tangential constraints during stationary holding may be difficult to extract in the presence of a torque. On the other hand, inertial torque experienced during movement may also potentially disrupt the grip-force adjustments, as the dynamical constraints clearly differ from the situation when no torque load is present. To address the influence of inertial torque loads, we instructed healthy adults to perform visually guided reaching movements in weightlessness while holding an unbalanced object relative to the grip axis. Weightlessness offered the possibility to remove gravitational constraints and isolate the effect of movement-related feedback on grip force adjustments. Grip-force adaptation rates were compared with a control group who manipulated a balanced object without any torque load and also in weightlessness. Our results clearly show that grip-force adaptation in the presence of a torque load is significantly slower, which suggests that the presence of torque loads experienced during movement may alter our internal estimates of how much force is required to hold an unbalanced object stable. This observation may explain why grasping objects around the expected location of the center of mass is such an important component of planning and control of manipulation tasks.
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Controlling torque and cutting costs: steerable drill bits deliver in Latin America
Energy Technology Data Exchange (ETDEWEB)
Barton, Steve; Garcia, Alexis; Amorim, Dalmo [ReedHycalog, Stonehouse (United Kingdom); Iramina, Wilson [University of Sao Paulo (USP), SP (Brazil); Herrera, Gabriel
2008-07-01
Tool face Control is widely regarded as one of the greatest directional drilling challenges with a Fixed Cutter (FC) drill bit on a Steerable Motor assembly. Tool face offset is proportional to the torque generated by the bit, and by nature, FC bits are capable of generating high levels of torque. If large changes in downhole torque are produced while drilling, this will cause rotation of the drill string, and loss of tool face orientation. This results in inefficient drilling and increases risk of bit and downhole tool damage. This paper examines the effect of various FC drill bit components to determine the key design requirements to deliver a smooth torque response and an improved directional performance. Included is a review of the results from comprehensive laboratory testing to determine the effectiveness of a number of different configurations of removable Torque Controlling Components (TCC). These, in combination with specific cutting structure layouts, combine to provide predictable torque response while optimized for high rates of penetration. In addition, unique gauge geometry is disclosed that was engineered to reduce drag and deliver improved borehole quality. This gauge design produces less torque when sliding and beneficial gauge pad interaction with the borehole when in rotating mode. Field performance studies from within Latin America clearly demonstrate that matching TCC, an optimized cutting structure, and gauge geometry to a steerable assembly delivers smooth torque response and improved directional control. Benefits with regard to improved stability are also discussed. Successful application has resulted in significant time and cost savings for the operator, demonstrating that Stability and Steerability improvements can be achieved with an increase in penetration rate. (author)
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Balancing of a power-transmission shaft with the application of axial torque
Zorzi, E. S.; Flemming, D.
1980-01-01
Evaluation of power transmission shafting for high-speed balancing has shown that when axial torque is applied, the imbalance response is altered. An increase in synchronous excitation always occurs if the axial torque level is altered from the value used during balancing; this was the case even when the shaft was balanced with torque applied. The twisting of the long slender shaft produces a change in the imbalance distribution sufficient to disrupt the balanced state. This paper presents a review of the analytic development of a weighted least squares approach to influence coefficient balancing and a review of experimental results. The analytic approach takes advantage of the fact that the past testing has shown that the influence coefficients are not significantly affected by the application of axial torque. The 3.60-m (12-ft) long aluminum shaft, 7.62 cm (3 in.) in diameter was run through the first flexural critical speed at torque levels ranging from zero-torque to 903.8 N-M (8000 lb-in.) in 112.9 N-M (1000 lb-in.) increments. Good comparison was achieved between predicted and experimental results.
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Accretion torques due to three-dimensional channelled flows in magnetic cataclysmic variables
International Nuclear Information System (INIS)
Campbell, C.G.
1986-01-01
Angular momentum transfer due to three-dimensional magnetically channelled accretion flows in cataclysmic binaries is considered. The white dwarf experiences a torque due to the twist in that part of its magnetic field which interacts with the accretion stream. The channelling process can also enhance angular momentum exchange between the stream and the orbit by increasing the gravitational torques. The components of the accretion torque are calculated for an arbitrary static magnetic orientation of the white dwarf, and their variation with orientation is presented. For high inclinations of the accreting pole to the orbital plane the component of the accretion torque parallel to this plane can be comparable to its perpendicular component. It is shown that the parallel component of the torque is still significant relative to the perpendicular component if material links to the white dwarf's magnetic field well away from the L 1 region. (author)
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Carlson, D.
2010-01-01
Joints within unconsolidated material such as glacial till can be primary avenues for the flow of electrical charge, water, and contaminants. To facilitate the siting and design of remediation programs, a need exists to map anisotropic distribution of such pathways within glacial tills by determining the azimuth of the dominant joint set. The azimuthal survey method uses standard resistivity equipment with a Wenner array rotated about a fixed center point at selected degree intervals that yields an apparent resistivity ellipse. From this ellipse, joint set orientation can be determined. Azimuthal surveys were conducted at 21 sites in a 500-km2 (193 mi2) area around Milwaukee, Wisconsin, and more specifically, at sites having more than 30 m (98 ft) of glacial till (to minimize the influence of underlying bedrock joints). The 26 azimuthal surveys revealed a systematic pattern to the trend of the dominant joint set within the tills, which is approximately parallel to ice flow direction during till deposition. The average orientation of the joint set parallel with the ice flow direction is N77??E and N37??E for the Oak Creek and Ozaukee tills, respectively. The mean difference between average direct observation of joint set orientations and average azimuthal resistivity results is 8??, which is one fifth of the difference of ice flow direction between the Ozaukee and Oak Creek tills. The results of this study suggest that the surface azimuthal electrical resistivity survey method used for local in situ studies can be a useful noninvasive method for delineating joint sets within shallow geologic material for regional studies. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.
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Explosive sport training and torque kinetics in children.
Dotan, Raffy; Mitchell, Cameron J; Cohen, Rotem; Gabriel, David; Klentrou, Panagiota; Falk, Bareket
2013-07-01
A high rate of force development (RFD) is often more important than maximal force in daily and sports activities. In children, resistance training has been shown to increase maximal force. It is unclear whether, or to what extent, can children improve RFD and force kinetics. For this study, we compared strength and force kinetics of boy gymnasts with those of untrained boys and untrained men. Eight boy gymnasts (age, 9.5 ± 1.2 y), 20 untrained boys (age, 10.1 ± 1.3 y), and 20 untrained men (age, 22.9 ± 4.4 y) performed maximal, explosive, isometric elbow flexions (EF) and knee flexions (KF). Peak torque (maximal voluntary contraction (MVC)), elapsed times to 10%-100% MVC, peak rate of torque development (RTDpk), and other kinetics parameters were determined. When gymnasts were compared with untrained boys, size-normalized EF MVC was 11%-20% higher, RTDpk was 32% higher, and times to 30% and 80% MVC were 16% and 55% shorter, respectively (p kinetics parameters were similar. These findings highlight the specificity of gymnastics training, which markedly elevated the torque kinetics of young, prepubertal boys to adult levels, but only moderately affected peak torque. It is suggested that neurologic adaptations, such as enhanced firing and activation rates or increased type II motor-unit recruitment, as well as changes in musculotendinous stiffness, could explain these findings.
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Directory of Open Access Journals (Sweden)
Ruppel Mirjana
2017-09-01
Full Text Available The motor precision of today’s neuroprosthetic devices that use artificial generation of limb motion using Functional Electrical Stimulation (FES is generally low. We investigate the adoption of natural co-activation strategies as present in antagonistic muscle pairs aiming to improve motor precision produced by FES. In a test in which artificial knee-joint movements were generated, we could improve the smoothness of FES-induced motion by 513% when applying co-activation during the phases in which torque production is switched between muscles – compared to no co-activation. We further demonstrated how the co-activation level influences the joint stiffness in a pendulum test.
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Angular dependence and symmetry of Rashba spin torque in ferromagnetic heterostructures
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.
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Angular dependence and symmetry of Rashba spin torque in ferromagnetic heterostructures
Ortiz Pauyac, Christian; Wang, Xuhui; Chshiev, Mairbek; Manchon, Aurelien
2013-01-01
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.
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Medeiros, Flávia V A; Vieira, Amilton; Carregaro, Rodrigo L; Bottaro, Martim; Maffiuletti, Nicola A; Durigan, João L Q
2015-01-01
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. To investigate the effects of skinfold thickness (SFT) on maximal NMES current intensity, NMES-evoked torque, and NMES-induced discomfort. 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). 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). 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.
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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.
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Knee extension torque variability after exercise in ACL reconstructed knees.
Goetschius, John; Kuenze, Christopher M; Hart, Joseph M
2015-08-01
The purpose of this study was to compare knee extension torque variability in patients with ACL reconstructed knees before and after exercise. Thirty two patients with an ACL reconstructed knee (ACL-R group) and 32 healthy controls (control group) completed measures of maximal isometric knee extension torque (90° flexion) at baseline and following a 30-min exercise protocol (post-exercise). Exercise included 30-min of repeated cycles of inclined treadmill walking and hopping tasks. Dependent variables were the coefficient of variation (CV) and raw-change in CV (ΔCV): CV = (torque standard deviation/torque mean x 100), ΔCV = (post-exercise - baseline). There was a group-by-time interaction (p = 0.03) on CV. The ACL-R group demonstrated greater CV than the control group at baseline (ACL-R = 1.07 ± 0.55, control = 0.79 ± 0.42, p = 0.03) and post-exercise (ACL-R = 1.60 ± 0.91, control = 0.94 ± 0.41, p = 0.001). ΔCV was greater (p = 0.03) in the ACL-R group (0.52 ± 0.82) than control group (0.15 ± 0.46). CV significantly increased from baseline to post-exercise (p = 0.001) in the ACL-R group, while the control group did not (p = 0.06). The ACL-R group demonstrated greater knee extension torque variability than the control group. Exercise increased torque variability more in the ACL-R group than control group. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
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Resistive wall tearing mode generated finite net electromagnetic torque in a static plasma
International Nuclear Information System (INIS)
Hao, G. Z.; Wang, A. K.; Xu, M.; Qu, H. P.; Peng, X. D.; Wang, Z. H.; Xu, J. Q.; Qiu, X. M.; Liu, Y. Q.
2014-01-01
The MARS-F code [Y. Q. Liu et al., Phys. Plasmas 7, 3681 (2000)] is applied to numerically investigate the effect of the plasma pressure on the tearing mode stability as well as the tearing mode-induced electromagnetic torque, in the presence of a resistive wall. The tearing mode with a complex eigenvalue, resulted from the favorable averaged curvature effect [A. H. Glasser et al., Phys. Fluids 18, 875 (1975)], leads to a re-distribution of the electromagnetic torque with multiple peaking in the immediate vicinity of the resistive layer. The multiple peaking is often caused by the sound wave resonances. In the presence of a resistive wall surrounding the plasma, a rotating tearing mode can generate a finite net electromagnetic torque acting on the static plasma column. Meanwhile, an equal but opposite torque is generated in the resistive wall, thus conserving the total momentum of the whole plasma-wall system. The direction of the net torque on the plasma is always opposite to the real frequency of the mode, agreeing with the analytic result by Pustovitov [Nucl. Fusion 47, 1583 (2007)]. When the wall time is close to the oscillating time of the tearing mode, the finite net torque reaches its maximum. Without wall or with an ideal wall, no net torque on the static plasma is generated by the tearing mode. However, re-distribution of the torque density in the resistive layer still occurs
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Goh, Colleen; Blanchard, Mary L; Crompton, Robin H; Gunther, Michael M; Macaulay, Sophie; Bates, Karl T
2017-10-01
Three-dimensional musculoskeletal models have become increasingly common for investigating muscle moment arms in studies of vertebrate locomotion. In this study we present the first musculoskeletal model of a western lowland gorilla hind limb. Moment arms of individual muscles around the hip, knee and ankle were compared with previously published data derived from the experimental tendon travel method. Considerable differences were found which we attribute to the different methodologies in this specific case. In this instance, we argue that our 3D model provides more accurate and reliable moment arm data than previously published data on the gorilla because our model incorporates more detailed consideration of the 3D geometry of muscles and the geometric constraints that exist on their lines-of-action about limb joints. Our new data have led us to revaluate the previous conclusion that muscle moment arms in the gorilla hind limb are optimised for locomotion with crouched or flexed limb postures. Furthermore, we found that bipedalism and terrestrial quadrupedalism coincided more regularly with higher moment arms and torque around the hip, knee and ankle than did vertical climbing. This indicates that the ability of a gorilla to walk bipedally is not restricted by musculoskeletal adaptations for quadrupedalism and vertical climbing, at least in terms of moment arms and torque about hind limb joints. © 2017 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.
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Torque Tension Testing of Fasteners used for NASA Flight Hardware Applications
Hemminger, Edgar G.; Posey, Alan J.; Dube, Michael J.
2014-01-01
The effect of various lubricants and other compounds on fastener torque-tension relationships is evaluated. Testing was performed using a unique test apparatus developed by Posey at the NASA Goddard Space Flight Center. A description of the test methodology, including associated data collection and analysis will be presented. Test results for 300 series CRES and A286 heat resistant fasteners, torqued into various types of inserts will be presented. The primary objective of this testing was to obtain torque-tension data for use on NASA flight projects.
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Electromagnetic forces and torques in nanoparticles irradiated by plane waves
International Nuclear Information System (INIS)
Garcia de Abajo, F.J.
2004-01-01
Optical tweezers and optical lattices are making it possible to control small particles by means of electromagnetic forces and torques. In this context, a method is presented in this work to calculate electromagnetic forces and torques for arbitrarily-shaped objects in the presence of other objects illuminated by a plane wave. The method is based upon an expansion of the electromagnetic field in terms of multipoles around each object, which are in turn used to derive forces and torques analytically. The calculation of multipole coefficients are obtained numerically by means of the boundary element method. Results are presented for both spherical and non-spherical objects
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Shot noise of spin current and spin transfer torque
International Nuclear Information System (INIS)
Yu Yunjin; Zhan Hongxin; Wan Langhui; Wang Bin; Wei Yadong; Sun Qingfeng; Wang Jian
2013-01-01
We report the theoretical investigation of the shot noise of the spin current (S σ ) and the spin transfer torque (S τ ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear S σ − V and S τ − V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage N τ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque N τ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period N τ (θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters. (paper)
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Sensorless Speed/Torque Control of DC Machine Using Artificial Neural Network Technique
Directory of Open Access Journals (Sweden)
Rakan Kh. Antar
2017-12-01
Full Text Available In this paper, Artificial Neural Network (ANN technique is implemented to improve speed and torque control of a separately excited DC machine drive. The speed and torque sensorless scheme based on ANN is estimated adaptively. The proposed controller is designed to estimate rotor speed and mechanical load torque as a Model Reference Adaptive System (MRAS method for DC machine. The DC drive system consists of four quadrant DC/DC chopper with MOSFET transistors, ANN, logic gates and routing circuits. The DC drive circuit is designed, evaluated and modeled by Matlab/Simulink in the forward and reverse operation modes as a motor and generator, respectively. The DC drive system is simulated at different speed values (±1200 rpm and mechanical torque (±7 N.m in steady state and dynamic conditions. The simulation results illustratethe effectiveness of the proposed controller without speed or torque sensors.
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Alterations in neuromuscular function in girls with generalized joint hypermobility.
Jensen, Bente Rona; Sandfeld, Jesper; Melcher, Pia Sandfeld; Johansen, Katrine Lyders; Hendriksen, Peter; Juul-Kristensen, Birgit
2016-10-03
Generalized Joint Hypermobility (GJH) is associated with increased risk of musculoskeletal joint pain. We investigated neuromuscular performance and muscle activation strategy. Girls with GJH and non-GJH (NGJH) performed isometric knee flexions (90°,110°,130°), and extensions (90°) at 20 % Maximum Voluntary Contraction, and explosive isometric knee flexions while sitting. EMG was recorded from knee flexor and extensor muscles. Early rate of torque development was 53 % faster for GJH. Reduced hamstring muscle activation in girls with GJH was found while knee extensor and calf muscle activation did not differ between groups. Flexion-extension and medial-lateral co-activation ratio during flexions were higher for girls with GJH than NGJH girls. Girls with GJH had higher capacity to rapidly generate force than NGJH girls which may reflect motor adaptation to compensate for hypermobility. Higher medial muscle activation indicated higher levels of medial knee joint compression in girls with GJH. Increased flexion-extension co-activation ratios in GJH were explained by decreased agonist drive to the hamstrings.
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Al-Thomali, Yousef; Mohamed, Roshan-Noor; Basha, Sakeenabi
2017-01-01
To evaluate the torque expression of self ligating (SL) orthodontic brackets and conventionally ligated brackets and the torque expression in active and passive SL brackets. Our systematic search included MEDLINE, EMBASE, CINAHL, PsychINFO, Scopus, and key journals and review articles; the date of the last search was April 4th 2016. We graded the methodological quality of the studies by means of the Quality Assessment Tool for Quantitative Studies, developed for the Effective Public Health Practice Project (EPHPP). In total, 87 studies were identified for screening, and 9 studies were eligible. The quality assessment rated one of the study as being of strong quality, 7 (77.78%) of these studies as being of moderate quality. Three out of 7 studies which compared SL and conventionally ligated brackets showed, conventionally ligated brackets with highest torque expression compared to SL brackets. Badawi showed active SL brackets with highest torque expression compared to passive SL brackets. Major and Brauchli showed no significant differences in torque expression of active and passive SL brackets. Conventionally ligated brackets presented with highest torque expression compared to SL brackets. Minor difference was recorded in a torque expression of active and passive SL brackets. Key words: Systematic review, self ligation, torque expression, conventional ligation.
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Torque vectoring for improving stability of small electric vehicles
Grzegożek, W.; Weigel-Milleret, K.
2016-09-01
The electric vehicles solutions based on the individually controlled electric motors propel a single wheel allow to improve the dynamic properties of the vehicle by varying the distribution of the driving torque. Most of the literature refer to the vehicles with a track typical for passenger cars. This paper examines whether the narrow vehicle (with a very small track) torque vectoring bring a noticeable change of the understeer characteristics and whether torque vectoring is possible to use in securing a narrow vehicle from roll over (roll mitigation). The paper contains road tests of the steering characteristics (steady state understeer characteristic quasi-static acceleration with a fixed steering wheel (SH = const) and on the constant radius track (R = const)) of the narrow vehicle. The vehicle understeer characteristic as a function of a power distribution is presented.
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Speed sensorless direct torque control of IMs with rotor resistance estimation
International Nuclear Information System (INIS)
Barut, Murat; Bogosyan, Seta; Gokasan, Metin
2005-01-01
Direct torque control (DTC) of induction motors (IMs) requires an accurate knowledge on the amplitude and angular position of the controlled flux in addition to the information related to angular velocity for velocity control applications. However, unknown load torque and uncertainties related to stator/rotor resistances due to operating conditions constitute major challenges for the performance of such systems. The determination of stator resistance can be performed by measurements, but methods must be developed for estimation and identification of rotor resistance and load torque. In this study, an EKF based solution is sought for determination of the rotor resistance and load torque as well as the above mentioned states required for DTC. The EKF algorithm used in conjunction with the speed sensorless DTC is tested under eleven scenarios comprised of various changes made in the velocity reference beside the load torque and rotor resistance values assigned in the model. With no a priori information in the estimated states and parameters, it has been demonstrated that the EKF estimation and sensorless DTC perform quite well in spite of the uncertainties and variations imposed on the system
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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.
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Analysis of the torque capacity of a completely customized lingual appliance of the next generation
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
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A Novel Cogging Torque Simulation Method for Permanent-Magnet Synchronous Machines
Directory of Open Access Journals (Sweden)
Chun-Yu Hsiao
2011-12-01
Full Text Available Cogging torque exists between rotor mounted permanent magnets and stator teeth due to magnetic attraction and this is an undesired phenomenon which produces output ripple, vibration and noise in machines. The purpose of this paper is to study the existence and effects of cogging torque, and to present a novel, rapid, half magnet pole pair technique for forecasting and evaluating cogging torque. The technique uses the finite element method as well as Matlab research and development oriented software tools to reduce numerous computing jobs and simulation time. An example of a rotor-skewed structure used to reduce cogging torque of permanent magnet synchronous machines is evaluated and compared with a conventional analysis method for the same motor to verify the effectiveness of the proposed approach. The novel method is proved valuable and suitable for large-capacity machine design.
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Quiescent H-mode operation using torque from non-axisymmetric, non-resonant magnetic fields
International Nuclear Information System (INIS)
Burrell, K.H.; Garofalo, A.M.; Osborne, T.H.; Snyder, P.B.; Solomon, W.M.; Park, J.-K.; Fenstermacher, M.E.; Orlov, D.M.
2013-01-01
Quiescent H-mode (QH-mode) sustained by magnetic torque from non-axisymmetric magnetic fields is a promising operating mode for future burning plasmas including ITER. Using magnetic torque from n = 3 fields to replace counter-I p torque from neutral beam injection, we have achieved long duration, counter-rotating QH-mode operation with neutral beam injection (NBI) torque ranging continuously from counter-I p up to co-I p values of about 1 N m. This co-I p torque is about 3 times the scaled torque that ITER will have. This range also includes operation at zero net NBI torque, applicable to rf wave heated plasmas. These n = 3 fields have been created using coils either inside or, most recently, outside the toroidal coils. Experiments utilized an ITER-relevant lower single-null plasma shape and were done with ITER-relevant values ν ped * ∼0.08, β T ped ∼ 1%$ and β N = 2. Discharges have confinement quality H 98y2 = 1.3, exceeding the value required for ITER. Initial work with low q 95 = 3.4 QH-mode plasmas transiently reached fusion gain values of G = β N H 89 /q 95 2 =0.4, which is the desired value for ITER; the limits on G have not yet been established. This paper also includes the most recent results on QH-mode plasmas run without n = 3 fields and with co-I p NBI; these shots exhibit co-I p plasma rotation and require NBI torque ⩾2 N m. The QH-mode work to date has made significant contact with theory. The importance of edge rotational shear is consistent with peeling–ballooning mode theory. We have seen qualitative and quantitative agreement with the predicted torque from neoclassical toroidal viscosity. (paper)
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Measurements of Inertial Torques on Sedimenting Fibers
Hamati, Rami; Roy, Anubhab; Koch, Don; Voth, Greg
2017-11-01
Stokes flow solutions predict that ellipsoids sedimenting in quiescent fluid keep their initial orientation. However, preferential alignment in low Reynolds number sedimentation is easily observed. For example, sun dogs form from alignment of sedimenting ice crystals. The cause of this preferential alignment is a torque due to non-zero fluid inertia that aligns particles with a long axis in the horizontal direction. These torques are predicted analytically for slender fibers with low Reynolds number based on the fiber diameter (ReD) by Khayat and Cox (JFM 209:435, 1989). Despite increasingly widespread use of these expressions, we did not find experimental measurements of these inertial torques at parameters where the theory was valid, so we performed a set of sedimentation experiments using fore-aft symmetric cylinders and asymmetric cylinders with their center of mass offset from their center of drag. Measured rotation rates as a function of orientation using carefully prepared glass capillaries in silicon oil show good agreement with the theory. We quantify the effect of finite tank size and compare with other experiments in water where the low ReD condition is not met. Supported by Army Research Office Grant W911NF1510205.
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Energy Technology Data Exchange (ETDEWEB)
Iwaji, Y.; Fukuda, S. (Hokkaido University, Sapporo (Japan))
1991-07-15
Sinusoidal inverters are getting more widely used keeping pace with the development of semiconductor switching elements. This paper discusses optimizing a PWM pulse pattern at an inverter output to drive an induction motor, proposes methods for improving distortion and torque ripples using a carrier frequency modulation (CFM), and describes a method for realizing the improvement through use of a single-chip microcomputer. The method defines evaluation parameters corresponding to the distortion and torque ripples, and optimizes the CFM depth to the parameters. The PWM pulse pattern has its voltage vector and time width so selected that the time integrated space vector of a three-phase voltage approaches a circular locus. Furthermore, the carrier frequency, that is the sampling frequency of the inverter, is also adjusted so that the above evaluation parameters are minimized. The addition of a new variable called the frequency modulation provides freedom in selecting an output characteristic as called for by the purpose. 12 refs., 18 figs.
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Energy Technology Data Exchange (ETDEWEB)
Fornel, B. de [Institut National Polytechnique, 31 - Toulouse (France)
2006-05-15
The asynchronous machine, with its low cost and robustness, is today the most widely used motor to make speed variators. However, its main drawback is that the same current generates both the magnetic flux and the torque, and thus any torque variation creates a flux variation. Such a coupling gives to the asynchronous machine a nonlinear behaviour which makes its control much more complex. The direct self control (DSC) method has been developed to improve the low efficiency of the scalar control method and for the specific railway drive application. The direct torque control (DTC) method is derived from the DSC method but corresponds to other type of applications. The DSC and DTC algorithms for asynchronous motors are presented in this article: 1 - direct control of the stator flux (DSC): principle, flux control, torque control, switching frequency of the inverter, speed estimation; 2 - direct torque control (DTC): principle, electromagnetic torque derivative, signals shape and switching frequency, some results, DTC speed variator without speed sensor, DTC application to multi-machine multi-converter systems; 3 - conclusion. (J.S.)
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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.
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Skyrmionic spin Seebeck effect via dissipative thermomagnonic torques
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.
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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.
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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....
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Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.
Melo, Ruth C; Takahashi, Anielle C M; Quitério, Robison J; Salvini, Tânia F; Catai, Aparecida M
2016-01-01
Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p torque was the only exercise tested that showed an interaction effect between age and muscle length (p torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.
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Directory of Open Access Journals (Sweden)
Gaohong Xu
2017-05-01
Full Text Available This paper proposes a novel permanent magnet (PM motor for high torque performance, in which hybrid PM material and asymmetric rotor design are applied. The hybrid PM material is adopted to reduce the consumption of rare-earth PM because ferrite PM is assisted to enhance the torque production. Meanwhile, the rotor structure is designed to be asymmetric by shifting the surface-insert PM (SPM, which is used to improve the torque performance, including average torque and torque ripple. Moreover, the reasons for improvement of the torque performance are explained by evaluation and analysis of the performances of the proposed motor. Compared with SPM motor and V-type motor, the merit of high utilization ratio of rare-earth PM is also confirmed, showing that the proposed motor can offer higher torque density and lower torque ripple simultaneously with less consumption of rare-earth PM.
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Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation
Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles
2011-10-01
In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.
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Torque Analysis of a Triple Acid-Etched Titanium Implant Surface
Directory of Open Access Journals (Sweden)
Ana Emília Farias Pontes
2015-01-01
Full Text Available The present study aimed to evaluate the removal torque of titanium implants treated with triple acid etching. Twenty-one rats were used in this study. For all animals, the tibia was prepared with a 2 mm drill, and a titanium implant (2 × 4 mm was inserted after treatment using the subtraction method of triple acid etching. The flaps were sutured. Seven animals were killed 14, 28, and 63 days after implant installation, and the load necessary for removing the implant from the bone was evaluated by using a torque meter. The torque values were as follows: 3.3 ± 1.7 Ncm (14 days, 2.2 ± 1.3 Ncm (28 days, and 6.7 ± 1.4 Ncm (63 days. The torque value at the final healing period (63 days was statistically significantly different from that at other time points tested (ANOVA, p=0.0002. This preliminary study revealed that treatment with triple acid etching can create a promising and efficient surface for the process of osseointegration.
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Interpersonal strategies for disturbance attenuation during a rhythmic joint motor action.
Melendez-Calderon, A; Komisar, V; Burdet, E
2015-08-01
Helping someone carry a table is fairly easy; however, our understanding of such joint motor actions is still poorly understood. We studied how pairs of human subjects (referred to as dyads) collaborate physically to attenuate external mechanical perturbations during a target tracking task. Subjects tracked a target moving in a slow and predictable way using wrist flexion/extension movements, with and without destabilizing torque perturbations. Dyad strategies were classified using interaction torques and muscular activity. During unperturbed interactions (baseline), the dyads tended to stabilize on a particular strategy. The baseline strategy was not the same in all dyads, suggesting that the solution to the task was not global but specific to each particular dyad. After several trials of unperturbed interactions, we introduced mechanical vibrations and analyzed the adaptation process. Dyads showed a tendency to counteract the external disturbances by first increasing co-contraction within each subject (independent co-contraction), and then raising the amount of opposing interaction torques (dyadic co-contraction) with increased perturbation amplitude. The introduction of perturbations impelled dyads to abandon their unperturbed baseline strategy and adopt a more common strategy across dyads, suggesting attractor solutions. Our results establish a framework for future human-human interaction studies, and have implications in human motor control as well as human-robot and robot-robot interactions. Copyright © 2015. Published by Elsevier Inc.
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Lattime, Scott B.; Borowski, Richard
2009-01-01
The EcoTurn Class K production prototypes have passed all AAR qualification tests and received conditional approval. The accelerated life test on the second set of seals is in progress. Due to the performance of the first set, no problems are expected.The seal has demonstrated superior performance over the HDL seal in the test lab with virtually zero torque and excellent contamination exclusion and grease retention.
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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....... This intuitive linear model is used to implement a DTC type controller that preserves all DTC advantages and eliminates its main drawback, the flux and torque ripple. Robust, fast, and ripple-free control is achieved by using Variable Structure Control (VSC) with proportional control in the vicinity...... robust stability analysis are presented. The sliding controller is compared with a linear DTC scheme, and experimental results for a sensorless IM drive validate the proposed solution....
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Onodera, Tomohiro; Majima, Tokifumi; Iwasaki, Norimasa; Kamishima, Tamotsu; Kasahara, Yasuhiko; Minami, Akio
2012-09-01
The stress distribution of an ankle under various physiological conditions is important for long-term survival of total ankle arthroplasty. The aim of this study was to measure subchondral bone density across the distal tibial joint surface in patients with malalignment/instability of the lower limb. We evaluated subchondral bone density across the distal tibial joint in patients with malalignment/instability of the knee by computed tomography (CT) osteoabsorptiometry from ten ankles as controls and from 27 ankles with varus deformity/instability of the knee. The quantitative analysis focused on the location of the high-density area at the articular surface, to determine the resultant long-term stress on the ankle joint. The area of maximum density of subchondral bone was located in the medial part in all subjects. The pattern of maximum density in the anterolateral area showed stepwise increases with the development of varus deformity/instability of the knee. Our results should prove helpful for designing new prostheses and determining clinical indications for total ankle arthroplasty.
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Control of spin-orbit torques through crystal symmetry in WTe2/ferromagnet bilayers
MacNeill, D.; Stiehl, G. M.; Guimaraes, M. H. D.; Buhrman, R. A.; Park, J.; Ralph, D. C.
2017-03-01
Recent discoveries regarding current-induced spin-orbit torques produced by heavy-metal/ferromagnet and topological-insulator/ferromagnet bilayers provide the potential for dramatically improved efficiency in the manipulation of magnetic devices. However, in experiments performed to date, spin-orbit torques have an important limitation--the component of torque that can compensate magnetic damping is required by symmetry to lie within the device plane. This means that spin-orbit torques can drive the most current-efficient type of magnetic reversal (antidamping switching) only for magnetic devices with in-plane anisotropy, not the devices with perpendicular magnetic anisotropy that are needed for high-density applications. Here we show experimentally that this state of affairs is not fundamental, but rather one can change the allowed symmetries of spin-orbit torques in spin-source/ferromagnet bilayer devices by using a spin-source material with low crystalline symmetry. We use WTe2, a transition-metal dichalcogenide whose surface crystal structure has only one mirror plane and no two-fold rotational invariance. Consistent with these symmetries, we generate an out-of-plane antidamping torque when current is applied along a low-symmetry axis of WTe2/Permalloy bilayers, but not when current is applied along a high-symmetry axis. Controlling spin-orbit torques by crystal symmetries in multilayer samples provides a new strategy for optimizing future magnetic technologies.
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Capparé, Paolo; Vinci, Raffaele; Di Stefano, Danilo Alessio; Traini, Tonino; Pantaleo, Giuseppe; Gherlone, Enrico Felice; Gastaldi, Giorgio
2015-10-01
Quantitative intraoperative evaluation of bone quality at implant placement site and postinsertion implant primary stability assessment are two key parameters to perform implant-supported rehabilitation properly. A novel micromotor has been recently introduced allowing to measure bone density at implant placement site and to record implant insertion-related parameters, such as the instantaneous, average and peak insertion torque values, and the insertion torque/depth integral. The aim of this study was to investigate in vivo if any correlation existed between initial bone-to-implant contact (BIC) and bone density and integral values recorded with the instrument. Twenty-five patients seeking for implant-supported rehabilitation of edentulous areas were consecutively treated. Before implant placement, bone density at the insertion site was measured. For each patient, an undersized 3.3 × 8-mm implant was placed, recording the insertion torque/depth integral values. After 15 minutes, the undersized implant was retrieved with a 0.5 mm-thick layer of bone surrounding it. Standard implants were consequently placed. Retrieved implants were analyzed for initial BIC quantification after fixation, dehydration, acrylic resin embedment, sections cutting and grinding, and toluidine-blue and acid fuchsine staining. Correlation between initial BIC values, bone density at the insertion site, and the torque/depth integral values was investigated by linear regression analysis. A significant linear correlation was found to exist between initial BIC and (a) bone density at the insertion site (R = 0.96, explained variance R(2) = 0.92) and (b) torque/depth integral at placement (R = 0.81, explained variance R(2) = 0.66). The system provided quantitative, reliable data correlating significantly with immediate postinsertion initial BIC, and could therefore represent a valuable tool both for clinical research and for the oral implantologist in his/her daily clinical
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Torres del Castillo, G.F; Méndez Garrido, A
2006-01-01
Making use of the fact that a 2l-pole can be represented by means of l vectors of the same magnitude, the torque on a quadrupole in an inhomogeneous external field is expressed in terms of the vectors that represent the quadrupole and the gradient of the external field. The conditions for rotational equilibrium are also expressed in terms of these vectors. Haciendo uso de que un multipolo de orden 2l puede representarse mediante l vectores de la misma magnitud, la torca sobre un cuadripolo...
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Signatures of asymmetric and inelastic tunneling on the spin torque bias dependence
Manchon, Aurelien; Zhang, S.; Lee, K.-J.
2010-01-01
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.
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Signatures of asymmetric and inelastic tunneling on the spin torque bias dependence
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.
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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.
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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.
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Analysis and Modelling of the Structural Components of the Elbow Joint
Romero Rey, Gregorio; Martínez Muneta, María Luisa; Gómez, M.; Mera Sánchez De Pedro, José Manuel
2013-01-01
A recent application of computer simulation is its use for the human body, which resembles a mechanism that is complemented by torques in the joints that are caused by the action of muscles and tendons. Among others, the application can be used to provide training in surgical procedures or to learn how the body works. Some of the other applications are to make a biped walk upright, to build robots that are designed on the human body or to make prostheses or robot arms to perform specific task...
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System and method for determining the net output torque from a waste heat recovery system
Tricaud, Christophe; Ernst, Timothy C.; Zigan, James A.
2016-12-13
The disclosure provides a waste heat recovery system with a system and method for calculation of the net output torque from the waste heat recovery system. The calculation uses inputs from existing pressure and speed sensors to create a virtual pump torque sensor and a virtual expander torque sensor, and uses these sensors to provide an accurate net torque output from the WHR system.
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The relationship between the applied torque and stresses in post-tension structures
International Nuclear Information System (INIS)
Liew, F.K.; Hamdan, S.; Osman, M.S.
2008-01-01
This paper presents the nondestructive testing (NDT) method to determine the resultant stresses in mild steel bar usually employed in structures. The technique utilized ultrasonic pulse-echo that determined the wave velocity change due to torque applied between bolt and nut. Mild steel bar with nominal diameter of 19 and 25mm were used. The specimen was loaded by means of a torque wrench that gave the required amount of moment (∼300Nm). This was carefully achieved manually. In order to measure the strain, strain gauges were employed. The direct strain gauge method gives the strain values. This strain is used to calculate the stress due to the applied load. The experiment had been carried out in a control environment with constant temperature. The relationship between torque-velocity, torque-strain and stress-strain is obtained and compared. The test results indicate that ultrasonic wave velocity decrease with the applied torque. This is due to degradation or loss of strength of the material. The potential of this NDT method to obtain structure quality and strength determination is discussed. (author)
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The relationship between the applied torque and stresses in post-tension structures
Energy Technology Data Exchange (ETDEWEB)
Liew, F.K.; Hamdan, S.; Osman, M.S. [Univ. Malaysia Sarawak, Faculty of Engineering, Kota Samarahan, Sarawak (Malaysia)
2008-09-15
This paper presents the nondestructive testing (NDT) method to determine the resultant stresses in mild steel bar usually employed in structures. The technique utilized ultrasonic pulse-echo that determined the wave velocity change due to torque applied between bolt and nut. Mild steel bar with nominal diameter of 19 and 25mm were used. The specimen was loaded by means of a torque wrench that gave the required amount of moment (∼300Nm). This was carefully achieved manually. In order to measure the strain, strain gauges were employed. The direct strain gauge method gives the strain values. This strain is used to calculate the stress due to the applied load. The experiment had been carried out in a control environment with constant temperature. The relationship between torque-velocity, torque-strain and stress-strain is obtained and compared. The test results indicate that ultrasonic wave velocity decrease with the applied torque. This is due to degradation or loss of strength of the material. The potential of this NDT method to obtain structure quality and strength determination is discussed. (author)
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Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction
Ortiz Pauyac, Christian
2016-01-01
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
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Goryca, Zbigniew; Paduszyński, Kamil; Pakosz, Artur
2018-03-01
This paper presents the results of field calculations of cogging torque for a 12-pole torque motor with an 18-slot stator. A constant angular velocity magnet and the same size gap between n-1 magnets were assumed. In these conditions, the effect of change of the n-th gap between magnets on the cogging torque was tested. Due to considerable length of the machine the calculations were performed using a 2D model. The n-th gap for which the cogging torque assumed the lowest value was evaluated. The cogging torque of the machine with symmetrical magnetic circuit (the same size of gap between magnets) was compared to the one of the asymmetrical machine. With proper choice of asymmetry, the cogging torque for the machine decreased by four times.