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1
Okazaki, Yoshimitsu, Emiko Hayakawa, Kazumasa Tanahashi, and Jun Mori. "Mechanical Performance of Metallic Bone Screws Evaluated Using Bone Models." Materials 13, no. 21 (October 29, 2020): 4836. http://dx.doi.org/10.3390/ma13214836.
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To evaluate mechanical performance properties of various types of cortical bone screw, cancellous bone screw, and locking bolt, we conducted torsional breaking and durability tests, screw driving torque tests into bone models, and screw pullout tests (crosshead speed: 10 mm/min) after driving torque tests. The 2° proof and rupture torques of a screw, which were estimated from torque versus rotational angle curves, increased with increasing core diameter of the screw. The durability limit of metallic screws obtained by four-point bending durability tests increased with increasing core diameter. The compressive, tensile, and shear strengths of the bone models used for the mechanical testing of orthopedic devices increased with increasing density of the bone model. The strength and modulus obtained for solid rigid polyurethane foam (SRPF) and cellular rigid polyurethane foam (CRPF) lay on the same straight line. Among the three strengths, the rate of increase in compressive strength with the increase in density was the highest. The maximum torque obtained by screw driving torque tests for up to 8.3 rotations (3000°) into the bone models tended to increase with increasing core diameter. In particular, the maximum torque increased linearly with increasing effective surface area of the screw, as newly defined in this work. The maximum pullout load increased linearly with increasing number of rotations and mechanical strength of the bone model. Screws with low driving torque and high pullout load were considered to have excellent fixation and are a target for development.
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Liu, Fuhao. "Dynamic analysis of drag torque for spur gear pairs considering the double-sided films." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 12 (February 10, 2016): 2253–62. http://dx.doi.org/10.1177/0954406216631370.
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Taking into account different drag torque, this paper investigates the influence of the lubricant films located in the backlash between meshing gear teeth pair on the gear dynamical behaviors. Numerical simulations show that the influence of the lubricant film on the coast side is significant under low loading, but under increased drag torques the influence is diminished. The shape of the hysteresis loop of double-sided films suggests that this model can make more sense. The sensitive of the drag torque is studied to illustrate the inverse relationship between drag torque and gear rattle: increased drag torque loading will increase to possibility of metal–metal contact which could generate noise, while decreased drag torque loading can promote noise due to rattle.
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Khorsandi, Farzaneh, and Paul D. Ayers. "The Effect of Friction on Actuation Torques of Foldable Rollover Protective Structures." Journal of Agricultural Safety and Health 24, no. 4 (2018): 227–42. http://dx.doi.org/10.13031/jash.12844.
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Abstract. The number of fatal tractor rollover accidents with an inoperative foldable rollover protective structure (FROPS) has increased sharply in recent years. Operators frequently leave the FROPS in the folded-down position after lowering the FROPS to pass a low overhead obstacle. One possible explanation for leaving the FROPS in the folded position is that raising and lowering the FROPS is a time-consuming and strenuous process. The actuation torques required to raise and lower a FROPS are not well known and may be influenced by friction. The actuation torques of ten FROPS from four different models were measured. One model FROPS was tested on seven different vehicles, and three models were tested separately. The dynamic and static (initiation and holding) actuation torques were measured to evaluate the effect of static and kinetic friction on actuation torque. The dynamic actuation torques were measured before and after greasing the FROPS. The proposed instruction to measure the actuation torque based on OECD Code 7 was evaluated. Results showed that friction has a significant effect on the measured actuation torque and can increase the actuation torque by up to 212%. The friction varies between FROPS of the same model, which is due to variations in the manufacturing, maintenance, and age of the FROPS. The friction force could be decreased by greasing the FROPS, and decreasing the friction increased the lowering resisting torques and decreased raising torques of FROPS. The measured actuation torque based on OECD Code 7 instruction (static holding) is not a constant value. The dynamic method is recommended for measuring FROPS actuation torques. Keywords: Actuating torque, Foldable rollover protective structure, FROPS, Safety, Standards, Tractor.
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Pesqueira, E. I. O., Cristiano Stefano Mucsi, and Jesualdo Luiz Rossi. "Influence of the Geometric Characteristics of the Mini-Implants on Mechanicals Properties Using Artificial Bone Similar to Anterior, Middle and Posterior Regions of the Jaws." Materials Science Forum 930 (September 2018): 276–82. http://dx.doi.org/10.4028/www.scientific.net/msf.930.276.
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The objective of this study was to identify the best torque of insertion and removal of mini-implants with a twin screw design (compact and self-drilling) into artificial bones with density and trabecular thickness, similar to anterior, middle and posterior regions of the jaws. Observation of the mini-implants surface using electron microscopy was performed before and after the tests. The torque values obtained during the insertion and removal was measured by digital torque wrench. The analyzed results led to the conclusion that the insertion and removal torques were larger with increase in bone density and cortical thickness. The design of the threads of the mini-implants influenced the insertion torque. Threads with smaller pitch increased the value of insertion torque. The anterior bone drilling installation reduces the insertion torque independent of bone density. Torque increased mainly by increasing the bone density and not necessarily with increased cortical thickness suggesting that the bone density of the trabecular bone must be considered in designing the installation of mini-implants.
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Eidietis, L., T. L. Forrester, and P. W. Webb. "Relative abilities to correct rolling disturbances of three morphologically different fish." Canadian Journal of Zoology 80, no. 12 (December 1, 2002): 2156–63. http://dx.doi.org/10.1139/z02-203.
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Responses of three fish species were measured following the addition of neutrally buoyant weight-float combinations that increased rolling instability. The three species were creek chub, Semotilus atromaculatus, largemouth bass, Micropterus salmoides, and bluegill, Lepomis macrochirus. Ability to correct posture was predicted to increase with fin size and body depth in the order creek chub < largemouth bass < bluegill. In a 90-s period, the least added torque causing fish to roll to 90° in response to disturbances, ΔT90, and the least added torque making fish unable to recover from rolling, ΔTcrit, were measured as limits of ability to correct postural disturbances. Contrary to expectations, creek chub required a 58% increase in body torque to reach ΔT90, significantly larger than the 11% increase for largemouth bass and 19% increase for bluegill. Similarly, ΔTcrit was a 78% increase in body torque for creek chub, 43% for largemouth bass, and 34% for bluegill. Increased rolling torques resulted in behaviors reducing and avoiding rolling, including tilting, which reduces metacentric height, inverted swimming, which stabilizes fish, and contacting surfaces, which generates static forces. The superior ability of creek chub to correct postural disturbances may be explained by a fin arrangement that facilitates interactions with the ground.
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Sharke, Paul. "Torque Take Off." Mechanical Engineering 122, no. 10 (October 1, 2000): 58–61. http://dx.doi.org/10.1115/1.2000-oct-1.
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This article focuses on that helicopters often display a rotor torque reading on their instrument panels to tell pilots how close they are flying to transmission design limits. With no measure of torque, a limit based on engine power is necessarily conservative. Torque monitors can increase a helicopter’s time between overhauls. Mechanical resonance, it seems, developed when the two engines were operated at matched torques. The torque meter lets the pilot split the torque to the two engines by 2 percent, diminishing any resonance. Permitted speculation, the Siemens researchers observed applications for their instrument beyond the traditional realm of torque measurement. In automotive applications, for instance, the researchers envision their torque measurement system one day being used in car engines to provide data in real time to the engine controls.
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Yoon, Sung Ho, and Young Eun Hwang. "Sealing performance test for V-insert clamp applicable to automobile exhaust pipes." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 10 (January 8, 2013): 2228–35. http://dx.doi.org/10.1177/0954406212473410.
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The sealing performance of V-insert clamp used in automobile exhaust pipes was examined for various applied torques by a specially designed pneumatic testing system. Axial clamping forces of V-insert clamp were evaluated through a clamping performance test. In the clamping performance test, increase in the torque showed gradual increase in the axial clamping force for all gaps between exhaust pipes that were considered. Slight increase in the torque resulted in relatively high axial clamping force. In the sealing performance test, when applied pressure was 50 kPa, the leak was not present in all applied torques due to no pressure change as a function of time. For 100 kPa, the leak was observed for applied torques of 3 N-m and lower. When V-insert clamp was used to join the pipes together, at least the applied torque of 4 N-m was needed in order for V-insert clamp to effectively function in the exhaustion system. Therefore, it can be concluded that V-insert clamp showed sufficient sealing performance to support the applied pressure of up to 100 kPa within the exhaustion system when relatively high torque was applied.
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KAKUCHI, Miyuki, Masahiro KUSAKA, Masaaki KIMURA, and Koichi KAIZU. "Study on Torque Increase in Magnetic Drive Torque Actuator Using FEM Analysis." Proceedings of Conference of Kansai Branch 2018.93 (2018): P006. http://dx.doi.org/10.1299/jsmekansai.2018.93.p006.
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Sidaway, Ben, and Amy (Robinson) Trzaska. "Can Mental Practice Increase Ankle Dorsiflexor Torque?" Physical Therapy 85, no. 10 (October 1, 2005): 1053–60. http://dx.doi.org/10.1093/ptj/85.10.1053.
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Abstract Background and Purpose. Mental practice has been shown to be effective in increasing the force production of the abductor digiti minimi muscle in the hand. The aim of this study was to determine whether mental practice could produce strength gains in the larger ankle dorsiflexor muscles, which are important during walking. Subjects. Twenty-four subjects were randomly assigned to a physical practice group, a mental practice group, or a control group (8 subjects per group). Methods. In the practice groups, subjects either physically or mentally practiced producing maximal isometric contractions for 3 sets of 10 repetitions, 3 times per week for 4 weeks. Changes in mean peak isometric torque normalized to body weight and the resulting percentage of improvement were analyzed across the 3 groups. Results. Differences in raw torque production after training in the 2 practice groups resulted in significant percentages of improvement for the physical practice group (25.28%) and the mental practice group (17.13%), but not for the control group (−1.77%). The 2 practice groups were not statistically different in their maximal torque-generating capacity after training. Discussion and Conclusion. These findings show that mental practice in people without impairments can lead to an increase in torque production similar to that produced by physical practice. Such a technique may prove to be a useful adjunct to traditional treatment options aimed at increasing muscle strength.
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Okubo, Hiroki, and Mont Hubbard. "Analysis of Arm Joint Torques at Ball-Release for Set and Jump Shots in Basketball." Proceedings 49, no. 1 (June 15, 2020): 4. http://dx.doi.org/10.3390/proceedings2020049004.
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A kinetic model of the shooting arms has estimated arm joint torques for one-hand set- and jump-shots in basketball. The dynamic model has three rigid planar links with rotational joints imitating an upper arm, forearm and hand with shoulder, elbow and wrist joints. In general shots controlled by hand, forearm and upper arm motions, there are many torque combinations of shoulder, elbow and wrist joints to produce shooters’ desired ball-release speed, angle and backspin angular velocity. The minimum of the sum of squares of the torque combinations exists at ball-release, when the release angular velocities of the hand and forearm are equal, and the release angular accelerations of the hand and forearm are also equal. Each torque of the shooting arm joints for the set-shot with upward shoulder speed is smaller than that for the jump-shot. Shoulder, elbow and wrist torques increase in proportion to horizontal shot distances. As release backspin angular speed increases, each of the shoulder, elbow and wrist torques also increases. The torques of the shoulder, elbow and hand affect the horizontal shot distance and the ball-release backspin.
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Savin, V. Yu, and V. Yu Ilyichev. "STUDY OF TORQUE NONUNIFORMITY IN DOUBLE-ACTION HYDRAULIC ROTARY VANE MO-TORS." Herald of Dagestan State Technical University. Technical Sciences 47, no. 1 (April 21, 2020): 39–47. http://dx.doi.org/10.21822/2073-6185-2020-47-1-39-47.
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Abstract. Aim. Hydraulic rotary vane motors rely on the principle of torque maintained at a nominal pressure. In this case, the most important parameter of the torque is its nonuniformity. The problem of determining nonuniform torque in hydraulic motors having ten and twelve vanes is investigated with the aim of ensuring the maximum stability of this parameter.Method. Braking torque occurs on the vanes of hydraulic rotary vane motors due to the pressure of the working fluid on the stator; the theoretical expression for torque does not take the braking effect of the vanes into account. Therefore, an expression is compiled for the braking torque of the vanes with a type of stator curve that provides constant acceleration of the vane relative to the rotor.Results. Plots of changes in braking torques were constructed for 10- and 12-vane motors. Ratios of the minimum and maximum braking torques equal to 0.33 and 0.5 for motors with ten and twelve vanes, respectively, were obtained.Conclusion. The torque nonuniformity coefficients for hydraulic motors for the given parameters of d =11,6% and d = 8,8% for motors having ten and twelve vanes, respectively, were obtained. The results of the analysis of the obtained parameters indicate a slight increase in the nonuniformity of torque in a ten-vane motor. In this case, a decrease in the number of vanes leads to an increase in the mechanical efficiency of the hydraulic machine.
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Üstün, Oğuz, and Mithat Önder. "An Improved Torque Sharing Function to Minimize Torque Ripple and Increase Average Torque for Switched Reluctance Motor Drives." Electric Power Components and Systems 48, no. 6-7 (April 20, 2020): 667–81. http://dx.doi.org/10.1080/15325008.2020.1797939.
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Hirashima, Masaya, Kazutoshi Kudo, Koji Watarai, and Tatsuyuki Ohtsuki. "Control of 3D Limb Dynamics in Unconstrained Overarm Throws of Different Speeds Performed by Skilled Baseball Players." Journal of Neurophysiology 97, no. 1 (January 2007): 680–91. http://dx.doi.org/10.1152/jn.00348.2006.
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This study investigated how the human CNS organizes complex three-dimensional (3D) ball-throwing movements that require both speed and accuracy. Skilled baseball players threw a baseball to a target at three different speeds. Kinematic analysis revealed that the fingertip speed at ball release was mainly produced by trunk leftward rotation, shoulder internal rotation, elbow extension, and wrist flexion in all speed conditions. The study participants adjusted the angular velocities of these four motions to throw the balls at three different speeds. We also analyzed the dynamics of the 3D multijoint movements using a recently developed method called “nonorthogonal torque decomposition” that can clarify how angular acceleration about a joint coordinate axis (e.g., shoulder internal rotation) is generated by the muscle, gravity, and interaction torques. We found that the study participants utilized the interaction torque to generate larger angular velocities of the shoulder internal rotation, elbow extension, and wrist flexion. To increase the interaction torque acting at these joints, the ball throwers increased muscle torque at the shoulder and trunk but not at the elbow and wrist. These results indicates that skilled ball throwers adopted a hierarchical control in which the proximal muscle torques created a dynamic foundation for the entire limb motion and beneficial interaction torques for distal joint rotations.
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Almeida, Gil Lúcio, Daniel M. Corcos, and Ziaul Hasan. "Horizontal-Plane Arm Movements With Direction Reversals Performed by Normal Individuals and Individuals With Down Syndrome." Journal of Neurophysiology 84, no. 4 (October 1, 2000): 1949–60. http://dx.doi.org/10.1152/jn.2000.84.4.1949.
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We examined the systematic variation in shoulder and elbow torque, as well as movement kinematics, for horizontal-plane arm movements with direction reversals performed by normal individuals and individuals with Down syndrome. Eight neurologically normal individuals and eight individuals with Down syndrome performed horizontal, planar reversal movements to four different target locations. The four locations of the targets were chosen such that there is a systematic increase in elbow interaction torque for each of the four different target locations. This systematic increase in interaction torque has previously been shown to lead to progressively larger movement reversal errors, and trajectories that do not show a sharp reversal of direction, for movements to and from the target in patients who have proprioceptive abnormalities. We computed joint torques at the elbow and shoulder and found a high correlation between elbow and shoulder torque for the neurologically normal subjects. The ratio of joint torques varied systematically with target location. These findings extend previously reported findings of a linear synergy between shoulder and elbow joints for a variety of point-to-point movements. There was also a correlation between elbow and shoulder torque in individuals with Down syndrome, but the magnitude of the correlation was less. The ratio of joint torques changed systematically with target direction in individuals with Down syndrome but was slightly different from the ratio observed for neurologically normal individuals. The difference in the ratio was caused by the generation of proportionately more elbow torque than shoulder torque. The fingertip path of individuals with Down syndrome showed a sharp reversal in moving toward and then away from the target. In this respect, they were similar to neurologically normal individuals but dissimilar to individuals with proprioceptive deficits. Finally, we observed that individuals with Down syndrome spend proportionately more time in the vicinity of the target than normal individuals. Collectively these results show that there is a systematic relationship between joint torques at the elbow and shoulder. This relationship is present for reversal movements and is also present in individuals with Down syndrome.
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Goldberg, J., and B. W. Peterson. "Reflex and mechanical contributions to head stabilization in alert cats." Journal of Neurophysiology 56, no. 3 (September 1, 1986): 857–75. http://dx.doi.org/10.1152/jn.1986.56.3.857.
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Five alert cats were tested for their responses to rotation in a device that allowed rotation of the head on the trunk about a vertical axis passing through the C1-C2 vertebral joint. Electrodes were implanted to record the horizontal and vertical electrooculogram and electromyographic (EMG) activity of the dorsal neck muscles splenius, biventer cervicus, and complexus. Head rotation and torque acting on the head were recorded in the horizontal plane during rotations in the 0.05-5.0 Hz frequency range. Responses were interpreted with reference to a closed-loop dynamic model of the head-neck system. Whole-body rotation (WBR) with no neck movement elicited a vestibulocollic reflex (VCR). Neck muscle EMG lagged the sinusoidal platform rotation by approximately 120 degrees at low frequencies, which represents a 60 degrees lead relative to a perfectly compensatory 180 degrees lag. This phase lead was related to the cumulative eye position of the accompanying horizontal vestibular nystagmus as reported by Vidal et al. Horizontal head torque exhibited a similar low-frequency behavior. At high frequencies, EMG exhibited a progressively increasing phase lead and gain increase typical of a second-order lead system as described in decerebrate cats. Torque, however, showed much less lead and gain increase, presumably because of the low-pass filter properties of the process coupling muscle excitation to torque. Head torque did exhibit a steep increase in gain with frequency and a phase approaching that of platform acceleration at high frequencies when weights were attached to the head to increase its moment of inertia. The same +40 dB/decade gain slope and phase approaching 0 degree was observed during WBR rotation of the anesthetized cat in which head inertia is the only factor contributing to the torque. This dynamic behavior was predicted by the inertial component of the model. In the alert unweighted cat, the inertial torque was smaller than VCR-generated torque at frequencies below 4 Hz. Rotation of the neck with the head held fixed in space (HFS rotation) elicited a cervicocollic reflex (CCR). Neck EMG response was very similar to that observed during WBR, both in dynamic behavior and overall gain. Torque, however, was consistently greater than that generated by WBR and showed a steady increase of 8 dB/decade as frequency rose. The added torque can be attributed to the viscoelastic properties of neck muscles. Driven rotation of the head on the fixed body elicited torques that could be closely approximated by a vector sum of torques observed during WBR and HFS rotations.(ABSTRACT TRUNCATED AT 400 WORDS)
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Kinoshita, Hiroshi, Lars Bäckström, J. Randall Flanagan, and Roland S. Johansson. "Tangential Torque Effects on the Control of Grip Forces When Holding Objects With a Precision Grip." Journal of Neurophysiology 78, no. 3 (September 1, 1997): 1619–30. http://dx.doi.org/10.1152/jn.1997.78.3.1619.
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Kinoshita, Hiroshi, Lars Bäckström, J. Randall Flanagan, and Roland S. Johansson. Tangential torque effects on the control of grip forces when holding objects with a precision grip. J. Neurophysiol. 78: 1619–1630, 1997. When we manipulate small objects, our fingertips are generally subjected to tangential torques about the axis normal to the grasp surface in addition to linear forces tangential to the grasp surface. Tangential torques can arise because the normal force is distributed across the contact area rather than focused at a point. We investigated the effects of tangential torques and tangential forces on the minimum normal forces required to prevent slips (slip force) and on the normal forces actually employed by subjects to hold an object in a stationary position with the use of the tips of the index finger and thumb. By changing the location of the object's center of gravity in relation to the grasp surface, various levels of tangential torque (0–50 N⋅mm) were created while the subject counteracted object rotation. Tangential force (0–3.4 N) was varied by changing the weight of the object. The flat grasp surfaces were covered with rayon, suede, or sandpaper, providing differences in friction in relation to the skin. Under zero tangential force, both the employed normal force and the slip force increased in proportion to tangential torque with a slope that reflected the current frictional condition. Likewise, with pure tangential force, these forces increased in proportion to tangential force. The effects of combined tangential torques and tangential forces on the slip force were primarily additive, but there was a significant interaction of these variables. Specifically, the increase in slip force for a given increment in torque decreases as a function of tangential force. A mathematical model was developed that successfully predicted slip force from tangential torque, tangential force, and an estimate of coefficient of static friction in the digit-surface interface. The effects of combined tangential torques and forces on the employed normal force showed the same pattern as the effects on the slip force. The safety margin against frictional slips, measured as the difference between the employed normal force and the slip force, was relatively small and constant across all tangential force and torque levels except at small torques (<10 N⋅mm). There was no difference in safety margin between the digits. In conclusion, tangential torque strongly influences the normal force required for grasp stability. When controlling normal force, people take into account, in a precise fashion, the slip force reflecting both tangential force and tangential torque and their interaction as well as the current frictional condition in the object-digit interface.
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Cerutti-Kopplin, Daiane, Dimas João Rodrigues Neto, Accácio Lins Do Valle, Jefferson Ricardo Pereira, and Luis Gustavo Nunes Dias Pinho. "Reverse torque values in indexed abutments." Journal of Research in Dentistry 1, no. 3 (September 1, 2013): 192. http://dx.doi.org/10.19177/jrd.v1e32013192-198.
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Mechanical stability of implant-abutment set is fundamentally important for the success in implant supported rehabilitation. For this, the knowledge about torque removal values is essential. In this way, the objective of this work was to evaluate the torque reverse values in indexed abutments of Morse Taper system. Five Morse taper implants with their respective abutments were tested (n=5). Each abutment received a sequence of two consecutive torques in insertion (15Ncm) with an interval of ten minutes, and one reverse torque, all measured by digital torque wrench. The t-student test with 5% significance was used to evaluate the data. The analysis of results showed there is statistical significant difference in reverse torque values between the insertion torque value and reverse torque value intra-group, the indexed abutments presented an average percentage of torque loosing of 15% (P=0.002). It is possible to conclude that the use of indexed abutments of Morse taper system presented statistical significant reduction of reverse torque values, which in turns increase the risk of no biomechanical instability.
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Kalaiselvan, Kathir Kishan, Yasushi Ido, Yuhiro Iwamoto, and Atsushi Toyouchi. "Experimental investigation of angle dependent torque properties of a particle rotary damper using a magnetic elastomer particle assemblage." International Journal of Applied Electromagnetics and Mechanics 64, no. 1-4 (December 10, 2020): 737–43. http://dx.doi.org/10.3233/jae-209385.
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Typical particle rotary dampers generate constant torque throughout the cycle of rotation. However, this research is focused on generating angle dependent torque i.e. different torque at different angles. The damper is designed to generate an elevated torque at a specific angle. This can be achieved by employing ferromagnetic particles and by introducing a permanent magnet in the damper. This study is carried out using two major parameters I) base torque which is the measure of damping capacity and II) percentage increase in torque which is the measure of angle dependency. From the experimental investigations, it has been found that I) base torque increases with packing fraction and rotational speed and decreases conditionally with the amount of carbonyl iron present in the particle while II) percentage increase in torque decreases with packing fraction, remains constant with rotational speed and increases conditionally with the amount of carbonyl iron present in the particle.
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Zhang, Li-Qun, Sun G. Chung, Yupeng Ren, Lin Liu, Elliot J. Roth, and W. Zev Rymer. "Simultaneous characterizations of reflex and nonreflex dynamic and static changes in spastic hemiparesis." Journal of Neurophysiology 110, no. 2 (July 15, 2013): 418–30. http://dx.doi.org/10.1152/jn.00573.2012.
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This study characterizes tonic and phasic stretch reflex and stiffness and viscosity changes associated with spastic hemiparesis. Perturbations were applied to the ankle of 27 hemiparetic and 36 healthy subjects under relaxed or active contracting conditions. A nonlinear delay differential equation model characterized phasic and tonic stretch reflex gains, elastic stiffness, and viscous damping. Tendon reflex was characterized with reflex gain and threshold. Reflexively, tonic reflex gain was increased in spastic ankles at rest ( P < 0.038) and was not regulated with muscle contraction, indicating impaired tonic stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction ( P < 0.012) than controls ( P < 0.023) and higher in dorsi-flexors at lower torques ( P < 0.038), primarily because of its increase at rest ( P = 0.045), indicating exaggerated phasic stretch reflex especially in more spastic plantar flexors, which showed higher phasic stretch reflex gain than dorsi-flexors ( P < 0.032). Spasticity was associated with increased tendon reflex gain ( P = 0.002) and decreased threshold ( P < 0.001). Mechanically, stiffness in spastic ankles was higher than that in controls across plantar flexion/dorsi-flexion torque levels ( P < 0.032), and the more spastic plantar flexors were stiffer than dorsi-flexors at comparable torques ( P < 0.031). Increased stiffness in spastic ankles was mainly due to passive stiffness increase ( P < 0.001), indicating increased connective tissues/shortened fascicles. Viscous damping in spastic ankles was increased across the plantar flexion torque levels and at lower dorsi-flexion torques, reflecting increased passive viscous damping ( P = 0.033). The more spastic plantar flexors showed higher viscous damping than dorsi-flexors at comparable torque levels ( P < 0.047). Simultaneous characterizations of reflex and nonreflex changes in spastic hemiparesis may help to evaluate and treat them more effectively.
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Linares-Guerrero, Esperanza, Melany L. Hunt, and Roberto Zenit. "Effects of inertia and turbulence on rheological measurements of neutrally buoyant suspensions." Journal of Fluid Mechanics 811 (December 13, 2016): 525–43. http://dx.doi.org/10.1017/jfm.2016.763.
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For low-Reynolds-number shear flows of neutrally buoyant suspensions, the shear stress is often modelled using an effective viscosity that depends only on the solid fraction. As the Reynolds number ($Re$) is increased and inertia becomes important, the effective viscosity also depends on the Reynolds number itself. The current experiments measure the torque for flows of neutrally buoyant particles in a coaxial-cylinder rheometer for solid fractions, $\unicode[STIX]{x1D719}$, from 10 % to 50 % and Reynolds numbers based on particle diameter from 2 to 1000. For experiments for Reynolds of $O(10)$ and solid fractions less than $30\,\%$, the effective viscosity increases with Reynolds number, in good agreement with recent numerical simulations found in the literature. At higher solid fractions over the same range of $Re$, the results show a decrease in torque with shear rate. For Reynolds numbers greater than 100 and lower solids concentrations, the effective viscosity continues to increase with Reynolds number. However, based on comparisons with pure fluid measurements the increase in the measured effective viscosity results from the transition to turbulence. The particles augment the turbulence by increasing the magnitude of the measured torques and causing the flow to transition at lower Reynolds numbers. For the highest solid fractions, the measurements show a significant increase in the magnitude of the torques, but the effective viscosity is independent of Reynolds number.
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Dudley, G. A., R. T. Harris, M. R. Duvoisin, B. M. Hather, and P. Buchanan. "Effect of voluntary vs. artificial activation on the relationship of muscle torque to speed." Journal of Applied Physiology 69, no. 6 (December 1, 1990): 2215–21. http://dx.doi.org/10.1152/jappl.1990.69.6.2215.
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The speed-torque relationship of the right knee extensor muscle group was investigated in eight untrained subjects (28 +/- 2 yr old). Torque was measured at a specific knee angle during isokinetic concentric or eccentric actions at nine angular velocities (0.17-3.66 rad/s) and during isometric actions. Activation was by "maximal" voluntary effort or by transcutaneous tetanic electrical stimulation that induced an isometric torque equal to 60% (STIM 1) or 45% (STIM 2) of the voluntary isometric value. Torque increased (P less than 0.05) to 1.4 times isometric as the speed of eccentric actions increased to 1.57 rad/s for STIM 1 and STIM 2. Thereafter, increases in eccentric speed did not further increase torque. Torque did not increase (P greater than 0.05) above isometric for voluntary eccentric actions. As the speed of concentric actions increased from 0.00 to 3.66 rad/s, torque decreased (P less than 0.05) more (P less than 0.05) for both STIM 1 and STIM 2 (two-thirds) than for voluntary activation (one-half). As a result of these responses, torque changed three times as much (P less than 0.05) across speeds of concentric and eccentric actions with artificial (3.4-fold) than voluntary (1.1-fold) activation. The results indicate that with artificial activation the normalized speed-torque relationship of the knee extensors in situ is remarkably similar to that of isolated muscle. The relationship for voluntary activation, in contrast, suggests that the ability of the central nervous system to activate the knee extensors during maximal efforts depends on the speed and type of muscle action performed.
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Wang, Dagang, Ruixin Wang, and Jun Zhang. "Dynamic brake characteristics of disc brake during emergency braking of the kilometer deep coal mine hoist." Advances in Mechanical Engineering 12, no. 5 (May 2020): 168781402091809. http://dx.doi.org/10.1177/1687814020918097.
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Dynamic brake characteristics of disc brake during emergency braking of the kilometer deep coal mine hoist were investigated in the present study. The theoretical model of dynamic brake torque of disc brake during emergency braking was given to explore dynamic brake torque properties of disc brake. The three-dimensional thermo-mechanical coupled finite element model of brake disc–brake shoe was established to explore thermo-mechanical characteristics of disc brake during emergency braking. Effects of effective mass, hoisting acceleration and deceleration, and maximum hoisting speed on dynamic brake torques, equivalent von Mises stress, and temperature fields of disc brake during emergency braking were presented. The results show that the evolutions of brake torque, equivalent stress, and temperature of disc brake present fluctuating characteristics. The dynamic brake torque shows the largest change amplitude during emergency braking in the hoisting stage of constant speed. The largest equivalent stress and temperature are both located near the third brake shoe along the rotational direction at each side. An increase in effective mass causes overall decreases in the peak values of brake torque, equivalent stress, and temperature during emergency braking. Increases in hoisting acceleration/deceleration and maximum hoisting speed cause the increases in the maximum equivalent stress and temperature during emergency braking as compared to the slight decrease in the maximum brake torque.
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Wang, Tao, and Qiang Wang. "Calculation of Axial Rolling Torque in Radial-Axial Ring Rolling Process." Applied Mechanics and Materials 633-634 (September 2014): 589–92. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.589.
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The importance of the axial rolling torque to design equipment and process is described. On the basis of the established formula of axial rolling force, the formula of axial rolling torque is derived by using the moving volume theory of energy method. The influence of processing parameters on the axial rolling torque is investigated. It is found that the axial rolling torque increases with the increase of the outer diameter of ring, and the axial rolling torque decreases with the increase of the inside diameter of ring. The greater the feed in axial direction, the greater the axial rolling torque. The correctness of the formula is verified by calculating actual examples.
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Dirba, J., L. Lavrinovicha, and R. Dobriyan. "Study of the Synchronous Reluctance Motor Design." Latvian Journal of Physics and Technical Sciences 53, no. 4 (August 1, 2016): 22–29. http://dx.doi.org/10.1515/lpts-2016-0025.
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AbstractThe paper focuses on studying the external-rotor synchronous reluctance motor. The analysis is performed to estimate the influence of the number of stator slots and non-magnetic areas in the rotor (i.e., flux barriers) on the electromagnetic torque and torque ripple of the studied motor. It is concluded that the increase in the number of stator slotsZ= 6 toZ= 18 causes an approximately twofold decrease in the ripple factor, but torque increases by 5 %. Electromagnetic torque will be increased approximately by 24 %, if non-magnetic flux barriers are created in the rotor of the studied synchronous reluctance motor.
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Qi, Yayun, and Huanyun Dai. "Influence of motor harmonic torque on wheel wear in high-speed trains." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 1 (February 21, 2019): 32–42. http://dx.doi.org/10.1177/0954409719830808.
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With the increase of train speed, the harmonic torque of the traction motor of a high-speed train is not a negligible source of excitation. In order to explore the influence of the harmonic torque of the motor on wheel wear, a high-speed EMU vehicle model was established based on the multibody dynamics theory. FASTSIM was used to calculate the wear parameters, and the Zobory wear model was used to calculate the depth of the wheel wear. The influence of the harmonic torque of the motor on the wear parameters and wear depth of high-speed trains under straight and curve conditions is calculated, respectively. The simulation results show that the harmonic torque has a large influence on the wheel rail vertical force and the longitudinal creep force and has little influence on the lateral creep force. With the 30% harmonic torque, the wheel rail vertical force increases by 7.6%, the longitudinal creep force increases by 15%, and the lateral creep force increases by 4%. The amplitude of the longitudinal creepage increases by 14.2% when the harmonic torque is 10%, and increases by 34.4% when the harmonic torque is 30%. When the harmonic torque increases, the wheel wear depth increases, the 10% harmonic torque increases by 3% and the 30% harmonic torque increases by 8%, and the increase of the motor harmonic component accelerates the wheel wear. At the same time, small longitudinal positioning stiffness can help to reduce the influence of the harmonic torque, and the selection of the longitudinal positioning stiffness needs to consider the dynamic performance of the vehicle.
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Kamoji, M. A., S. B. Kedare, and S. V. Prabhu. "Experimental Investigations on the Effect of Overlap Ratio and Blade Edge Conditions on the Performance of Conventional Savonius Rotor." Wind Engineering 32, no. 2 (March 2008): 163–78. http://dx.doi.org/10.1260/030952408784815826.
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The torque of a conventional Savonius rotor is studied experimentally for overlap ratio from 0.10 to 0.70, blade edge condition (flat and round) and the change in Reynolds number. The results indicate that the coefficient of static torque improves marginally for round edged rotors for rotor angles up to 45°. The coefficient of static torque decreases as the overlap ratio is increased to 0.70 from 0.50 and is independent of the Reynolds numbers studied in the range between 120000 to 200000. Wind tunnel blockage ratio is studied. The power coefficient increases with the increase in the Reynolds number, whereas the coefficient of static torque is independent of the Reynolds number in the range studied. The coefficient of power, torque coefficient and coefficient static torque are independent of blockage ratios at a given Reynolds number.
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Watanabe, Renato N., Fernando H. Magalhães, Leonardo A. Elias, Vitor M. Chaud, Emanuele M. Mello, and André F. Kohn. "Influences of premotoneuronal command statistics on the scaling of motor output variability during isometric plantar flexion." Journal of Neurophysiology 110, no. 11 (December 1, 2013): 2592–606. http://dx.doi.org/10.1152/jn.00073.2013.
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This study focuses on neuromuscular mechanisms behind ankle torque and EMG variability during a maintained isometric plantar flexion contraction. Experimentally obtained torque standard deviation (SD) and soleus, medial gastrocnemius, and lateral gastrocnemius EMG envelope mean and SD increased with mean torque for a wide range of torque levels. Computer simulations were performed on a biophysically-based neuromuscular model of the triceps surae consisting of premotoneuronal spike trains (the global input, GI) driving the motoneuron pools of the soleus, medial gastrocnemius, and lateral gastrocnemius muscles, which activate their respective muscle units. Two types of point processes were adopted to represent the statistics of the GI: Poisson and Gamma. Simulations showed a better agreement with experimental results when the GI was modeled by Gamma point processes having lower orders (higher variability) for higher target torques. At the same time, the simulations reproduced well the experimental data of EMG envelope mean and SD as a function of mean plantar flexion torque, for the three muscles. These results suggest that the experimentally found relations between torque-EMG variability as a function of mean plantar flexion torque level depend not only on the intrinsic properties of the motoneuron pools and the muscle units innervated, but also on the increasing variability of the premotoneuronal GI spike trains when their mean rates increase to command a higher plantar flexion torque level. The simulations also provided information on spike train statistics of several hundred motoneurons that compose the triceps surae, providing a wide picture of the associated mechanisms behind torque and EMG variability.
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KAKUCHI, Miyuki, Koichi KAIZU, Masahiro KUSAKA, and Masaaki KIMURA. "Study on Torque Increase in Magnetic Drive Torque Actuator Using Superelastic Material and Ferromagnetic Material." Proceedings of The Manufacturing & Machine Tool Conference 2018.12 (2018): D16. http://dx.doi.org/10.1299/jsmemmt.2018.12.d16.
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Zheng, Zhi-Ying, Quan-Zhong Liu, Yong-Kang Deng, and Biao Li. "Multi-objective optimization design for the blade angles of hydraulic torque converter with adjustable pump." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 13 (March 4, 2020): 2523–36. http://dx.doi.org/10.1177/0954406220909853.
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To improve the efficiency of a hydraulic torque converter with adjustable pump at low load and thus increase the operation scope of high efficiency, multi-objective optimization design is carried out for the blade angles by incorporating three-dimensional steady computational fluid dynamics numerical simulation, design of experiments, Kriging surrogate model and multi-objective genetic algorithm. The results show that the angle of blade trailing edge in first-stage stator is the main influencing factor of the efficiency of hydraulic torque converter with adjustable pump. All the peak efficiencies of hydraulic torque converter with adjustable pump at three openings of the pump are improved after optimization, and the increased extent increases with decreasing opening of the pump. The operation scope of high efficiency consequently increases from 2.46 to 2.67. Besides, the improvement for the efficiency of hydraulic torque converter with adjustable pump is achieved by increasing the efficiency of the pump. The increase of angle of blade trailing edge in first-stage stator and the decrease of angle of blade leading edge in second-stage turbine after optimization induce the positive angle of attack at the inlet of second-stage turbine, thus realizing the performance optimization of hydraulic torque converter with adjustable pump. This also explains the increased proportion of the torque of second-stage turbine at larger speed ratios after optimization and the fact that the angle of blade trailing edge in first-stage stator is the main influencing factor of the efficiency of hydraulic torque converter with adjustable pump. The established multi-objective optimization method provides a reference solution for the optimization design of blade angles and for the improvement of integrated efficiency of hydraulic torque converter.
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Cai, Yu Qiang, and Na Xing. "The Analysis on the Starting Friction Torque Increase of Magnetic Fluid Revolving Sealing." Applied Mechanics and Materials 275-277 (January 2013): 429–32. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.429.
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Abstract. Magnetic fluid revolving sealing is widely used in modern industry. In the process of application, it is founded that the starting friction torque is very large, particularly at lower temperature. This problem has become a key factor restricting the application of magnetic fluid rotation sealing. In this paper, the mechanism of starting torque increase is analyzed, based on the change of microstructure and its viscosity. After analysis , such conclusion is obtained , which can be described: to a certain sealing structure, the type of magnetic fluid, size distribution of magnetic particles as well as the working condition concluding temperature, magnetic field gradient and the revolving velocity of shaft is the main influence factor of starting friction torque . It is very useful to reduce the starting friction torque.
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Elvin, Niell, Alex Elvin, Cornie Scheffer, Steven Arnoczky, Edwin Dillon, and P. J. Erasmus. "A Preliminary Study of Patellar Tendon Torques during Jumping." Journal of Applied Biomechanics 25, no. 4 (November 2009): 360–68. http://dx.doi.org/10.1123/jab.25.4.360.
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The etiology of patellar tendinopathy (jumper’s knee) has been attributed to a significant increase in patellar tendon torques associated with jumping. While some investigators have suggested that patellar tendon torques are greater during takeoff, little is known about the relative magnitudes of patellar tendon torques during takeoff and landing. We hypothesized that peak patellar tendon torques are greater in jump takeoff than in landing, and that there is a linear correlation between jump height and peak patellar tendon torque. Seven asymptomatic, recreational male athletes each performed a series of 21 jumps ranging from low to maximal height. A calibrated fiber-optic sensor, implanted transversely within the patellar tendon was used to measure the knee torque during takeoff and landing. There was no significant difference in the peak patellar tendon torque experienced during takeoff and landing within individuals. There was a moderate correlation (r= .64) between maximum takeoff patellar tendon torques and jump height. There was a weak correlation (r= .52) between maximum landing patellar tendon torques and jump height. There was a moderate correlation (r= .67) between maximum 60°/s isokinetic extension torque and maximum jump height. The lack of a strong correlation between jump height and patellar tendon forces during takeoff or landing suggests that these forces may be technique dependent. Therefore, modifying takeoff and/or landing techniques could reduce patellar tendon force and potentially lessen the incidence of patellar tendinopathy.
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Chun, Koay Seong, Salmah Husseinsyah, and Chan Ming Yeng. "Torque rheological properties of polypropylene/cocoa pod husk composites." Journal of Thermoplastic Composite Materials 30, no. 9 (November 30, 2015): 1217–27. http://dx.doi.org/10.1177/0892705715618743.
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The torque rheological properties of plastic wood composites are important to practical processing, but the research in this field is rare. In present, a Brabender plastrograph torque rheometer was used to analyse the rheological behavior of polypropylene (PP)/cocoa pod husk (CPH) composites. The effect of processing parameter, filler content, and addition of maleated polypropylene (MAPP) on torque rheological properties was investigated. The torque rheological data found that the processing torque increased with the increases of rotor speed, filler content, and addition of MAPP. The PP/CPH composites melt behavior as pseudoplastics and shear thinning occurred at higher shear rate. The decrease of power law index ( n) evidenced the pseudoplasticity of PP/CPH composites increased at higher filler content and presence of MAPP. The increase of viscosity on PP/CPH was due to filler–filler interaction at higher filler content and strong filler–matrix adhesion after addition of MAPP. The activation energy of PP/CPH composites also increased with higher amount of CPH and addition of MAPP.
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Li, Li Yun. "Research on Variable Transmission Efficiency of Automobile Transmission Based on the MASTA Software." Applied Mechanics and Materials 389 (August 2013): 398–403. http://dx.doi.org/10.4028/www.scientific.net/amm.389.398.
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The thesis built the simulation model of automobile variable transmission driving efficiency, and calculated the transmission efficiency by using the MASTA software under different conditions. The simulation results showed that the reverse transmission efficiency is the lowest. With gears forward 1 ~ 4, its transmission efficiency increased gradually, while the fifth gear is overdrive, therefore its transmission efficiency is lower than the fourth direct file. The transmission efficiency of the same gear increases and then decreases with the increase of the torque input. While the range of the transmission efficiency between different speed increases along with the increase of the torque. With the increase of the rotational speed of the gearbox, the transmission efficiency increase gradually, but the increase amplitude reduces gradually. The great method provides some reference for the study of the transmission efficiency.
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Sotto-Maior, Bruno Salles, Eduardo Passos Rocha, Erika Oliveira de Almeida, Amilcar Chagas Freitas-Júnior, Rodolfo Bruniera Anchieta, and Altair Antoninha Del Bel Cury. "Influence of high insertion torque on implant placement: an anisotropic bone stress analysis." Brazilian Dental Journal 21, no. 6 (2010): 508–14. http://dx.doi.org/10.1590/s0103-64402010000600005.
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The aim of this study was to evaluate the influence of the high values of insertion torques on the stress and strain distribution in cortical and cancellous bones. Based on tomography imaging, a representative mathematical model of a partial maxilla was built using Mimics 11.11 and Solid Works 2010 softwares. Six models were built and each of them received an implant with one of the following insertion torques: 30, 40, 50, 60, 70 or 80 Ncm on the external hexagon. The cortical and cancellous bones were considered anisotropic. The bone/implant interface was considered perfectly bonded. The numerical analysis was carried out using Ansys Workbench 10.0. The convergence of analysis (6%) drove the mesh refinement. Maximum principal stress (σmax) and maximum principal strain (εmax) were obtained for cortical and cancellous bones around to implant. Pearson's correlation test was used to determine the correlation between insertion torque and stress concentration in the periimplant bone tissue, considering the significance level at 5%. The increase in the insertion torque generated an increase in the σmax and εmax values for cortical and cancellous bone. The σmax was smaller for the cancellous bone, with greater stress variation among the insertion torques. The εmax was higher in the cancellous bone in comparison to the cortical bone. According to the methodology used and the limits of this study, it can be concluded that higher insertion torques increased tensile and compressive stress concentrations in the periimplant bone tissue.
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Mitsumata, Chiharu, Satoshi Tomita, Takeshi Seki, and Masaki Mizuguchi. "Simple Analysis for Frequency Increase in Spin Torque Oscillation." IEEE Transactions on Magnetics 48, no. 11 (November 2012): 3955–57. http://dx.doi.org/10.1109/tmag.2012.2201700.
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Li, Dan, Yu Ye Xu, Zheng He Qiu, and Yong Lin Zheng. "Numerical Simulation on the Torsion Behavior of '+'-Shaped Columns under the Actions of Pressure and Torque." Applied Mechanics and Materials 105-107 (September 2011): 796–99. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.796.
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Nonlinear finite element analysis (FEA) for the torsion behavior of reinforced concrete '+'-shaped columns with various axial load ratios was carried out by the general software ANSYS. Then a comparison between the FEA calculations and the test results is made. The numerical examples show that: (1) the cracking torque and ultimate torque of reinforced concrete '+'-shaped columns under the combined actions of axial force and torque can be predicted with a reasonable accuracy. (2) the axial ratio has significant effects on the torsion behavior '+'-shaped columns. The cracking torque and ultimate torque of '+'-shaped columns increase with an increase of axial load ratio. Comparing with reinforced concrete '+'-shaped column with an axial load ratio of 0.063, the cracking torque and ultimate torque of reinforced concrete '+'-shaped columns with axial load ratios of 0.189 and 0.314 were increased by 28.3% and 71.9%, 79.4% and 96.0%, respectively.
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Logan, Lindsey M., Jennifer A. Semrau, Tyler Cluff, Stephen H. Scott, and Sean P. Dukelow. "Effort matching between arms depends on relative limb geometry and personal control." Journal of Neurophysiology 121, no. 2 (February 1, 2019): 459–70. http://dx.doi.org/10.1152/jn.00346.2018.
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Proprioception encompasses our sense of position and movement of our limbs, as well as the effort with which we engage in voluntary actions. Historically, sense of effort has been linked to centrally generated signals that elicit voluntary movements. We were interested in determining the effect of differences in limb geometry and personal control on sense of effort. In experiment 1, subjects exerted either extension or flexion torques to resist a torque applied by a robot exoskeleton to their reference elbow. They attempted to match this torque by exerting an equal effort torque (in a congruent direction with the reference arm) with their opposite (matching) arm in different limb positions (±15°). Subjects produced greater matching torque when their matching arm exerted effort toward the mirrored position of the reference (e.g., reference/matching arms at 90°/105° elbow flexion) vs. away (e.g., 90°/75° flexion). In experiment 2, a larger angular difference between arms (30°) resulted in a larger discrepancy in matched torques. Furthermore, in both experiments 1 and 2, subjects tended to overestimate the reference arm torque. This motivated a third experiment to determine whether providing more personal control might influence perceived effort and reduce the overestimation of the reference torques that we observed ( experiments 3a and 3b). Overestimation of the matched torques decreased significantly when subjects self-selected the reference torque that they were matching. Collectively, our data suggest that perceived effort between arms can be influenced by signals relating to the relative geometry of the limbs and the personal control of motor output during action. NEW & NOTEWORTHY This work highlights how limb geometry influences our sense of effort during voluntary motor actions. It also suggests that loss of personal control during motor actions leads to an increase in perceived effort.
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Montgomery, Melissa M., and Sandra J. Shultz. "Isometric Knee-Extension and Knee-Flexion Torque Production During Early Follicular and Postovulatory Phases in Recreationally Active Women." Journal of Athletic Training 45, no. 6 (November 1, 2010): 586–93. http://dx.doi.org/10.4085/1062-6050-45.6.586.
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Abstract Context: Acute decreases in strength have been associated with risky biomechanical strategies that might predispose one to injury. Whether acute changes in thigh muscle torque occur across the menstrual cycle remains equivocal. Objective: We compared maximal voluntary isometric contraction (MVIC) torque of the knee flexors and extensors between the early follicular (EF) and either the early luteal (EL) or midluteal (ML) phases, which were confirmed by serum hormone concentrations. We expected that MVIC torques would increase from the EF to the EL phase after estradiol peaked and before increased exposure to progesterone. Design: Cohort study. Setting: Applied Neuromechanics Research Laboratory. Patients or Other Participants: Seventy-one recreationally active women (age range, 18–30 years). Intervention(s): The MVICs were measured 1 day during menses and 1 day during the 8 days after ovulation. Participants were grouped by the hormone profile of their luteal test days as EL phase, ML phase, or anovulatory cycle. Main Outcome Measure(s): The MVIC torque of knee flexors and extensors (Nm/kg), estradiol (pg/mL), progesterone (ng/mL), and testosterone (ng/dL). Results: We tested 29 women during their EL phases, 32 during their ML phases, and 10 during anovulatory cycles. Although we observed relatively large individual changes in sex hormone concentrations and MVIC torques across the 2 test sessions, we observed no difference in MVIC torque between test phases (F1,68 = 1.17, P = .28) or among groups by test phase (F2,68 = 0.31, P = .74). Conclusions: Thigh MVIC torque did not change from time of menses (when estradiol and progesterone were lowest) to time in the luteal phase after an unopposed estradiol rise or combined estradiol and progesterone rise. However, these findings were limited to MVIC torque production measured at 2 different times, and further research examining these relationships at multiple times and using other measures of neuromuscular function is needed.
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Warren, Gordon L., John M. Fennessy, and Melinda L. Millard-Stafford. "Strength loss after eccentric contractions is unaffected by creatine supplementation." Journal of Applied Physiology 89, no. 2 (August 1, 2000): 557–62. http://dx.doi.org/10.1152/jappl.2000.89.2.557.
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This study's objective was to determine whether 14 days of dietary creatine supplementation preceding an injurious bout of eccentric contractions affect the in vivo strength loss of mouse anterior crural muscles. Three groups of nine mice each were fed a meal diet for 14 days, one group at each of three levels of creatine supplementation (i.e., 0, 0.5, and 1% creatine). Electrically stimulated concentric, isometric, and eccentric contraction torques produced about the ankle were measured both before and after a bout of 150 eccentric contractions. Tibialis anterior muscle creatine concentration was significantly increased by the supplementation, being 12% higher in the mice fed the 1% creatine diet compared with control mice. After the bout of eccentric contractions, the reductions in torque (i.e., 46–58%) were similar for the isometric contraction, all eccentric contractions, and the slow (i.e., ≤200o/s) concentric contractions; above 200o/s, the percent reduction in concentric torque increased progressively to 85–88% at 1,000–1,200o/s. However, there was no effect of creatine supplementation on the isometric torque loss or on the torque loss at any eccentric or concentric angular velocity ( P ≥ 0.62). In conclusion, a moderate increase in muscle creatine concentration induced by dietary supplementation in mice does not affect the strength loss after eccentric contractions.
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Lim, Seon-A., Jung-Yul Cha, and Chung-Ju Hwang. "Insertion Torque of Orthodontic Miniscrews According to Changes in Shape, Diameter and Length." Angle Orthodontist 78, no. 2 (March 1, 2008): 234–40. http://dx.doi.org/10.2319/121206-507.1.
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Abstract Objective: To determine the variation in the insertion torque of orthodontic miniscrews according to the screw length, diameter, and shape. Materials and Methods: The maximum insertion torque (MIT) was measured using a torque tester at a constant speed of 3 rotations per minute. Cylindrical and taper type of miniscrews (Biomaterials Korea Inc, Seoul, Korea) with different lengths, diameters, and pitches were tested. Results: The results showed that the insertion torque significantly increased with increasing screw length (P < .01). In particular, there was a significant increase in torque with increasing screw length and diameter (P < .01). An analysis of the serial insertion torque of miniscrews revealed the cylindrical type screw to have much higher insertion torque at the incomplete screw thread, while the taper type screw showed a much higher insertion torque at the final inclination part of the screw thread. The insertion torque was affected by the outer diameter, length, and shape in that order. Conclusions: An increase in screw diameter can efficiently reinforce the initial stability of the miniscrew, but the proximity of the root at the implanted site should be considered.
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Saumur, Tyler M., and Stephen D. Perry. "Using Motor Imagery Training to Increase Quadriceps Strength: A Pilot Study." European Neurology 80, no. 1-2 (2018): 87–92. http://dx.doi.org/10.1159/000494091.
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Background: Motor imagery training implements neural adaptation theory to improve muscle strength without physically performing muscle contractions. To date, motor imagery training research regarding the efficacy of improving torque of the quadriceps over a brief training period is limited. Objective: To determine the impact of a 3-week motor imagery training on peak torque during knee extension. Method: Ten young, healthy volunteers were randomly assigned to 1 of 3 groups over a 3-week period: strength training, motor imagery training and control. Results: Following training, an increase in peak torque was observed in all strength training participants (mean change of 38 ± 15%) and in 2 members of the motor imagery training group (45 ± 10%). Conclusion: Brief periods of motor imagery training may have the potential to improve quadriceps strength; however, more research is needed with larger populations to test this hypothesis.
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Housh, Terry J., Glen O. Johnson, Dona J. Housh, Jeffrey R. Stout, Joseph P. Weir, Loree L. Weir, and Joan M. Eckerson. "Isokinetic Peak Torque in Young Wrestlers." Pediatric Exercise Science 8, no. 2 (May 1996): 143–55. http://dx.doi.org/10.1123/pes.8.2.143.
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The purpose of the present study was to examine age-related changes in isokinetic leg flexion and extension peak torque (PT), PT/body weight (PT/BW), and PT/fat-free weight (PT/FFW) in young wrestlers. Male wrestlers (N = 108; age M ± SD = 11.3 ± 1.5 years) volunteered to be measured for peak torque at 30, 180, and 300° · s−1. In addition, underwater weighing was performed to determine body composition characteristics. The sample was divided into six age groups (8.1−8.9, n = 10; 9.0−9.9, n= 11; 10.0−10.9, n = 25; 11.0−11.9, n = 22; 12.0−12.9, n = 28; 13.0−13.9, n = 12), and repeated measures ANOVAs with Tukey post hoc comparisons showed increases across age for PT, PT/BW, and PT/FFW. The results of this study indicated that there were age-related increases in peak torque that could not be accounted for by changes in BW or FFW. It is possible that either an increase in muscle mass per unit of FFW, neural maturation, or both, contributes to the increase in strength across age in young male athletes.
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Itami, Yasuo, Teruhisa Mihata, Michelle H. McGarry, Charles C. Lin, Nilay A. Patel, Adam Kantor, Masashi Neo, and Thay Q. Lee. "Effect of Increased Scapular Internal Rotation on Glenohumeral External Rotation and Elbow Valgus Load in the Late Cocking Phase of Throwing Motion." American Journal of Sports Medicine 46, no. 13 (September 28, 2018): 3182–88. http://dx.doi.org/10.1177/0363546518800267.
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Background: Scapular dyskinesis among throwers is thought to affect kinetic chain function and increase the load demands on the shoulder and/or elbow. However, the biomechanical relationship between scapular orientation and elbow valgus load, which is associated with ulnar collateral ligament (UCL) injury, has not been determined. Purpose: To evaluate the effect of increased scapular internal rotation (IR) and glenohumeral external rotation (GHER) on elbow valgus load in a static simulation of the late cocking phase of throwing. Study Design: Controlled laboratory study. Methods: Seven fresh-frozen male cadaveric upper extremities were used with a custom testing system to simulate the late cocking phase. First, the authors evaluated the effect of increasing scapular IR on maximum GHER and forearm angle (forearm axis relative to the ground). Each parameter was evaluated at 20° to 40° (5° increments) of scapular IR by applying 2.2-N·m external rotation torque to the humerus and 0.75-N·m valgus torque to the forearm. Next, to evaluate elbow valgus stability, the humerus was locked in maximal GHER at 40° of scapular IR, and sequentially increasing torque (0.75-7.5 N·m by 0.75-N·m increments) was applied to the forearm. Valgus angle and joint gap were evaluated at each torque. Results: Increases in scapular IR ≥5° significantly decreased GHER ( P < .01). With increasing valgus torque, forearm angle also increased linearly ( R2 = 0.85, P < .001). To compensate for the GHER deficit at 40° of scapular IR, a linear regression model showed that 25.3 N·m of valgus torque would be necessary to reach the original forearm position. In the intact condition, applying elbow valgus torque ≥5.25 N·m significantly increased valgus angle and the joint gap ( P < .01). Conclusion: Increased scapular IR significantly decreased GHER. Compensation for the GHER deficit significantly increased the elbow valgus load required to reach the same forearm position. Clinical Relevance: Increased scapular IR may increase the risk of elbow UCL injury among throwing athletes.
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Peng, Jifeng. "Effects of Aerodynamic Interactions of Closely-Placed Vertical Axis Wind Turbine Pairs." Energies 11, no. 10 (October 21, 2018): 2842. http://dx.doi.org/10.3390/en11102842.
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In this study, a numerical model was developed to study the effects of aerodynamic interactions between a pair of counter-rotating vertical axis wind turbines (VAWTs) in close proximity. In this model, the rotor rotation is not prescribed as a constant as in most other studies, but is determined by the moment of inertia and the total torque of the rotor, including the aerodynamic torque, generator torque, and a torque representing friction. This model enables study of the behavior of the rotor under an arbitrary ambient wind profile. The model was applied to an isolated rotor with five straight J-blades and pairs of identical rotors placed in close proximity. Compared with an isolated rotor, the aerodynamic interactions between the pair of rotors enhance the aerodynamic torques on the rotors and significantly increase the turbine power output on a per unit basis. The enhancement in turbine power output due to aerodynamic enhancement decreases with the distance between the pair of rotors.
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Crevecoeur, F., T. Giard, J. L. Thonnard, and P. Lefèvre. "Adaptive control of grip force to compensate for static and dynamic torques during object manipulation." Journal of Neurophysiology 106, no. 6 (December 2011): 2973–81. http://dx.doi.org/10.1152/jn.00367.2011.
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Manipulating a cup by the handle requires compensating for the torque induced by the moment of the mass of the cup relative to the location of the handle. In the present study, we investigated the control strategy of subjects asked to perform grip-lift movements with an object with center of mass located away from the grip axis. Participants were asked to lift the manipulandum with a two-fingers precision grip and stabilize it in front of a visual target. Subjects showed a gradual and slow adaptation of the grip-force scaling across trials: the grip force tended to decrease slowly, and the temporal coordination between grip-force and load-torque rates displayed gradually, better-coordinated patterns. Importantly, this adaptation was much slower than the stabilization of the same parameters measured either when no torque came into play or after previous adaptation to the presence of a torque. In contrast, the maximum rotation induced by the torque was controlled efficiently after only few trials, and an unexpected decrease in the tangential torque produced significant overcompensation. An unexpected increase in torque produced a consistent opposite effect. This shows that the compensation for the dynamic torque was based on an anticipatory, dynamic counter-torque produced by the arm and wrist motor commands. The comparatively slow stabilization of grip-force control suggests a specific adaptation process engaged by the presence of the torque. This paradigm, including tangential torques, clearly constitutes a powerful tool to extract the adaptive component of grip control during object manipulation.
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Li, Zifeng, Chaoyue Zhang, Wenming Ren, and Jianwei Ma. "Study of Radial Vibration Impact on Friction and Torque of Rotary Drill String." Shock and Vibration 2020 (July 24, 2020): 1–10. http://dx.doi.org/10.1155/2020/8852530.
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During extended-reach well drilling, the torque of a rotary drill string is too large in the horizontal section, which results in the failure of the drill string. The effect of radial vibration on the friction and torque of the rotary drill string is unclear. In this work, first, the principle of the impact of radial vibration on the friction and torque of the rotary drill string in the horizontal section is analysed. Then, joints with an elliptical outer edge of the section are designed, which can generate low-amplitude vibration as the drill string rotates owing to the interaction with the wellbore wall. The radial vibration characteristics can be tuned by changing the major to minor radius ratio of the ellipse. A self-developed experimental device was designed to test the performance of tools with reduced friction and torque. The drill string torque with different penetration rates, rotation speeds, and ratios of the major radius to minor radius of the ellipse were systematically studied. The experimental results show that the average and the maximum amplitudes of the torque fluctuation first decrease to the lowest value and then increase with the increase of the ratio. When the ratio reaches 1.065, the average and the maximum amplitudes of the torque fluctuation evidently reduce; therefore, a joint with a ratio of 1.065 can effectively reduce frictional torque. The average torque reduces when the penetration rate and rotation speed decrease. At rotation speeds of 45 and 60 r/min, the maximum amplitude of torque fluctuation increases first and then decreases with an increase in penetration rate, and it reaches a maximum value at a penetration rate of 22.5 m/h. The fundamental frequency of torque fluctuation is almost linearly related to rotation speed, which is irrelevant to the penetration rate and the ratio of major to minor radius of the ellipse.
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Pravinya Sam, Suresh Venugopalan, and Dhanraj Ganapathy. "Effect of Wet Field on the DE Torque Values of Abutment Screws." International Journal of Research in Pharmaceutical Sciences 11, SPL3 (September 18, 2020): 843–46. http://dx.doi.org/10.26452/ijrps.v11ispl3.3034.
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Screw loosening is amongst the most prevalent mechanical problems in dental implant prosthetics. Clinicians will know if the reverse Detorque values are compromised by contamination of the implant abutment screw hole either by blood , saliva or saline. Research have shown that the drying of the implant cavity may decrease the preload value when the abutment screw is closed and thereafter increase the likelihood of abutment screw loosening. Mobility of the prosthesis, or screw fracture and increase the risk of peri-implant soft-tissue inflammation. This study aims to assess and compare the effect of wet and dry fields while torqueing the abutment screws on the DE torque values. 40 Nobel bio care implant analogues mounted in plaster models were used in this study. The samples were divided into four groups dry abutment screws, artificial saliva, blood and normal saline. All the abutment screws were tightened till 20 Ncm and left aside for 15 minutes. After 15 minutes the abutment screw were DE torqued, and the DE torque values were noted for tall the groups. When analysed using paired sample t-test there was no significant difference with artificial saliva (p=0.269). There was statistical difference with blood (p=0.00) and with saline (p=0.00). Based on this study, the presence of saliva decreases the DE torque values of the abutment screws, whereas Blood and saline increase the DE torque values of the abutment screws. The presence of blood clot might be the reason for the increase in DE torque values which might decrease once the clot disintegrates. Clinicians should prevent contamination of the screw hole by blood and saliva; if contamination arises, sanitation of the infected screw and also the screw hole until final tightening is advised.
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Cui, Hongwei, Zisheng Lian, Long Li, and Qiliang Wang. "Analysis of influencing factors on oil film shear torque of hydro-viscous drive." Industrial Lubrication and Tribology 70, no. 7 (September 10, 2018): 1169–75. http://dx.doi.org/10.1108/ilt-05-2017-0137.
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Purpose The hydro-viscous drive (HVD) has been widely used in fan transmission in vehicles, fans, and scraper conveyors for step-less speed regulating and soft starting. It is an efficient method to save energy and reduce consumption. This study aims to analyze the influencing factors of oil film shear torque accurately. Design/methodology/approach The shear torque calculation model of double arc oil groove friction pairs was established. The influence of groove structure parameters on shear torque was analyzed. The interaction between viscosity temperature and shear torque was considered. Meanwhile, the equivalent radius was calculated when the rupture of oil film appeared. Finally, the test rig of torque characteristics was set up. The variance of shear torque with the input rotation speed under different oil film thickness, different oil temperature, and different flow rate was seen. Findings The results show that the shear torque increases with the growth of rotation speed. However, the increase of torque is quite gradual because of the effect of the change of viscosity, which is caused by the rise of temperature. The shear torque increases with the decrease of thickness, the increase of inlet flow rate, and the decrease of inlet oil temperature. Meanwhile, when the feeding flow rate is less than the theoretical, the oil film gets ruptured and the shear torque decreases sharply. Originality/value The influence on shear torque during full film shear stage in HVD can be achieved much more accurately through both experimental research and theoretical modeling in which groove parameters, influence of temperature, and oil film rupture are considered. Therefore, the shear torque of HVD can be predicted by theoretical model and experimental research in full film shear stage.
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Brown, A. B., N. McCartney, and D. G. Sale. "Positive adaptations to weight-lifting training in the elderly." Journal of Applied Physiology 69, no. 5 (November 1, 1990): 1725–33. http://dx.doi.org/10.1152/jappl.1990.69.5.1725.
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Maximal weight-lifting performance, isometric strength, isokinetic torque, whole muscle and individual fiber cross-sectional areas, and muscle evoked contractile properties were assessed in 14 elderly males before and after 12 wk of weight-lifting training. Dynamic elbow flexion training of one arm resulted in a significant 48% mean increase in the maximal load that could be lifted once (1 RM) and a smaller improvement in isokinetic torque (8.8%) but no change in isometric strength. In the contralateral control arm, 1 RM and isokinetic torque increased by 12.7 and 6.5%, respectively, but isometric strength did not change. The interpolated twitch technique confirmed complete motor unit activation during a maximal isometric contraction of the elbow flexors before and after the training. Bilateral leg press training effected mean increases of 17 and 23% in isokinetic torque and dynamic lifting capacity, respectively. The mean maximal cross-sectional area of the elbow flexors (biceps brachii and brachialis) increased by 17.4% in the trained arm but did not change the control arm. The increase in the mean area of type II fibers in the biceps brachii muscle in the trained arm (30.2%) was greater than the corresponding change in the control arm (10.7%, P less than 0.05). The most significant change in the evoked contractile properties of the trained elbow flexors was the increase in twitch half-relaxation time. It is concluded that older individuals retain the potential for significant increases in strength performance and upper limb muscle hypertrophy in response to overload training.
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Raianov, Timur A. "Overview of new types of torque force sensors." Transportation Systems and Technology 6, no. 1 (March 30, 2020): 5–14. http://dx.doi.org/10.17816/transsyst2020615-14.
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In recent years, modern torque measurement systems have become very popular. they are used in road, rail, aviation and ship transport, as well as in the pulp, paper, and metallurgical industries. These metrological systems provide accurate torque measurement in difficult operating conditions as well as in aggressive environments. Thanks to the introduction of microprocessors in these devices, it became possible to increase the speed, it became possible to connect automatic torque tracking systems via a network interface to a single automatic control center and to perform remote control of torque sensors. With the use of modern software increases communication automatic torque measurement systems. Various software models are being developed for automatic torque measurement systems that have the ability to either partially simulate this system or work as an assistant device adapting automatic measurement systems to various uncertainties such as ambient temperature and properties of ferromagnetic materials. Safety of operation of transport systems, load-lifting devices and production facilities is increased.
The purpose of this article is to review and analyze new types of torque sensors well-known manufacturers. The design and composition of modern measuring systems are considered and their advantages and disadvantages are analyzed. The technical description for each of the torque converters is given.