scholarly journals Dynamic analysis of a ten-link tooth-lever differential transmission

2021 ◽  
Vol 939 (1) ◽  
pp. 012024
Author(s):  
A Abdukarimov ◽  
I Saidakulov
Keyword(s):  
High Speed ◽  
Reaction Force ◽  
Transmission Mechanism ◽  
Force Analysis ◽  
Axis Of Rotation ◽  
Processed Material ◽  
Differential Transmission ◽  
External Forces ◽  
Force Calculation ◽  
Force Characteristics

Abstract This article discusses the dynamics of a ten-link tooth-lever differential transmission mechanism. The force analysis of the transmission mechanism is given in order to find the dependence for determining the reaction in kinematic pairs and the balancing moment of the pair of forces and to show some features of the tooth-lever transmission mechanism. The force calculation was carried out taking into account the accelerated movement of links since their acceleration in modern high-speed machines is very significant. To obtain a more accurate concept of the external forces and moments loading the transmission mechanism in the accelerated movement of the links, the dynamics of the transient process of roller technological machines was considered. Cases of feeding the processed material were considered both from the side of the intermediate gears and from the side opposite to the parasitic gears. Dependencies were obtained to determine the force characteristics of this mechanism. Cases of pressure unloading and overloading on the processed material from the side of the free shaft, depending on the location of the transmission mechanism are shown. The dependence of the reaction force of intermediate gears on their own axes of rotation on the angle between the levers is shown. With an increase in the angle between the levers, the reaction of the intermediate gears on the axis of rotation increases.

Intramolecular Proton Transfer in the Isomerization of Hydroxyacetone: A Detailed Characterization Based on Reaction Force Analysis and the Bond Fragility Spectrum

2020 ◽  
Author(s):  
Wallace Derricotte ◽  
Huiet Joseph
Keyword(s):  
Chemical Potential ◽  
Reaction Force ◽  
Intramolecular Proton Transfer ◽  
Intermediate Energy ◽  
Force Analysis ◽  
Activation Energy Barrier ◽  
Detailed Characterization ◽  
Proton Transfers ◽  
Reaction Force Constant

The mechanism of isomerization of hydroxyacetone to 2-hydroxypropanal is studied within the framework of reaction force analysis at the M06-2X/6-311++G(d,p) level of theory. Three unique pathways are considered: (i) a step-wise mechanism that proceeds through formation of the Z-isomer of their shared enediol intermediate, (ii) a step-wise mechanism that forms the E-isomer of the enediol, and (iii) a concerted pathway that bypasses the enediol intermediate. Energy calculations show that the concerted pathway has the lowest activation energy barrier at 45.7 kcal mol<sup>-1</sup>. The reaction force, chemical potential, and reaction electronic flux are calculated for each reaction to characterize electronic changes throughout the mechanism. The reaction force constant is calculated in order to investigate the synchronous/asynchronous nature of the concerted intramolecular proton transfers involved. Additional characterization of synchronicity is provided by calculating the bond fragility spectrum for each mechanism.

scholarly journals Acute Effects of Handheld Loading on Standing Broad Jump in Youth Athletes

2021 ◽  
Vol 18 (9) ◽  
pp. 5046
Author(s):  
Wei-Hsun Tai ◽  
Ray-Hsien Tang ◽  
Chen-Fu Huang ◽  
Shin-Liang Lo ◽  
Yu-Chi Sung ◽  
...  
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sampling Rate ◽  
Random Order ◽  
Horizontal Distance ◽  
Acute Effects ◽  
Vertical Ground Reaction Force ◽  
Strength And Conditioning ◽  
Peak Knee

The study aimed to investigate the acute effects of handheld loading on standing broad jump (SBJ) performance and biomechanics. Fifteen youth male athletes (mean age: 14.7 ± 0.9 years; body mass: 59.3 ± 8.0 kg; height: 1.73 ± 0.07 m) volunteered to participate in the study. Participants were assigned to perform SBJ with and without 4 kg dumbbells in a random order. Kinematic and kinetic data were collected using 10 infrared high-speed motion-capture cameras at a 250 Hz sampling rate and two force platforms at a 1000 Hz sampling rate. A paired t-test was applied to all variables to determine the significance between loading and unloading SBJs. Horizontal distance (p < 0.001), take-off distance (p = 0.001), landing distance (p < 0.001), horizontal velocity of center of mass (CoM; p < 0.001), push time (p < 0.001), vertical impulse (p = 0.003), and peak horizontal and vertical ground reaction force (GRF; p < 0.001, p = 0.017) were significantly greater in loading SBJ than in unloading SBJ. The take-off vertical velocity of CoM (p = 0.001), take-off angle (p < 0.001), peak knee and hip velocity (p < 0.001, p = 0.007), peak ankle and hip moment (p = 0.006, p = 0.011), and peak hip power (p = 0.014) were significantly greater in unloading SBJ than in loading SBJ. Conclusions: Acute enhancement in SBJ performance was observed with handheld loading. The present findings contribute to the understanding of biomechanical differences in SBJ performance with handheld loading and are highly applicable to strength and conditioning training for athletes.

scholarly journals Infinite Element Static-Dynamic Unified Artificial Boundary

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zhiqiang Song ◽  
Fei Wang ◽  
Yujie Liu ◽  
Chenhui Su
Keyword(s):  
Reaction Force ◽  
Tangential Direction ◽  
Dynamic Effects ◽  
Artificial Boundary ◽  
Infinite Element ◽  
Dynamic Synthesis ◽  
Dynamic Boundary ◽  
Static Calculation ◽  
Force Calculation ◽  
External Wave

The method, which obtains a static-dynamic comprehensive effect from superposing static and dynamic effects, is inapplicable to large deformation and nonlinear elastic problems under strong earthquake action. The static and dynamic effects must be analyzed in a unified way. These effects involve a static-dynamic boundary transformation problem or a static-dynamic boundary unified problem. The static-dynamic boundary conversion method is tedious. If the node restraint reaction force caused by a static boundary condition is not applied, then the model is not balanced at zero moment, and the calculation result is distorted. The static numerical solution error is large when the structure possesses tangential static force in a viscoelastic static-dynamic unified boundary. This paper proposed a new static-dynamic unified artificial boundary based on an infinite element in ABAQUS to solve static-dynamic synthesis effects conveniently and accurately. The static and dynamic mapping theories of infinite elements were introduced. The characteristic of the infinite element, which has zero displacement at faraway infinity, was discussed in theory. The equivalent nodal force calculation formula of infinite element unified boundary was deduced from an external wave input. A calculation and application program of equivalent nodal forces was developed using the Python language to complete external wave inputting. This new method does not require a static and dynamic boundary transformation and import of stress field and constraint counterforce of boundary nodes. The static calculation precision of the infinite element unified boundary is more improved than the viscoelastic static-dynamic unified boundary, especially when the static load is in the tangential direction. In addition, the foundation simulation range of finite field can be significantly reduced given the utilization of the infinite element static dynamic unified boundary. The preciseness of static calculation and dynamic calculation and static-dynamic comprehensive analysis are unaffected.

scholarly journals Differential muscle function between muscle synergists: long and lateral heads of the triceps in jumping and landing goats (Capra hircus)

2008 ◽  
Vol 105 (4) ◽  
pp. 1262-1273 ◽  
Author(s):  
Andrew M. Carroll ◽  
David V. Lee ◽  
Andrew A. Biewener
Keyword(s):  
Muscle Function ◽  
High Speed ◽  
Muscle Activation ◽  
Reaction Force ◽  
Elbow Flexion ◽  
Capra Hircus ◽  
Triceps Brachii ◽  
Joint Work ◽  
Long Head ◽  
Lateral Head

We investigate how the biarticular long head and monoarticular lateral head of the triceps brachii function in goats ( Capra hircus) during jumping and landing. Elbow moment and work were measured from high-speed video and ground reaction force (GRF) recordings. Muscle activation and strain were measured via electromyography and sonomicrometry, and muscle stress was estimated from elbow moment and by partitioning stress based on its relative strain rate. Elbow joint and muscle function were compared among three types of limb usage: jump take-off (lead limb), the step prior to jump take-off (lag limb), and landing. We predicted that the strain and work patterns in the monoarticular lateral head would follow the kinematics and work of the elbow more closely than would those of the biarticular long head. In general this prediction was supported. For instance, the lateral head stretched (5 ± 2%; mean ± SE) in the lead and lag limbs to absorb work during elbow flexion and joint work absorption, while the long head shortened (−7 ± 1%) to produce work. During elbow extension, both muscles shortened by similar amounts (−10 ± 2% long; −13 ± 4% lateral) in the lead limb to produce work. Both triceps heads functioned similarly in landing, stretching (13 ± 3% in the long head and 19 ± 5% in the lateral) to absorb energy. In general, the long head functioned to produce power at the shoulder and elbow, while the lateral head functioned to resist elbow flexion and absorb work, demonstrating that functional diversification can arise between mono- and biarticular muscle agonists operating at the same joint.

scholarly journals Problems of Clamping Rotary Tools

2014 ◽  
Vol 11 (2) ◽  
pp. 12-15
Author(s):  
Jaroslav Kunstfeld ◽  
Josef Brychta
Keyword(s):  
Service Life ◽  
High Speed ◽  
Small Deviation ◽  
Basic Function ◽  
Rotary Tool ◽  
Axis Of Rotation ◽  
Tool Axis ◽  
Machine Spindle ◽  
Cutting Point ◽  
Proper Operation

Abstract The basic function of all rotary tool clamps used is to clamp a tool firmly and with as small deviation of the tool axis from the axis of rotation of the machine tool spindle as possible throughout the service life of both the tool and the clamp. Another important function of a clamp is to bring the cutting lubricant to the cutting point. A lubricant pressure of 60 and more bars is currently used there. To ensure the proper operation and long service life of the machine spindle, it is necessary that, especially in the case of high-speed machines, the clamp with the tool clamped meets the specified condition of the overall unbalance.

Nonlinear Reaction Force Analysis for Characterization of Breast Tissues

2012 ◽  
pp. 125-134 ◽  
Author(s):  
Mariko Tsukune ◽  
Yo Kobayashi ◽  
Takeharu Hoshi ◽  
Yasuyuki Shiraishi ◽  
Tomoyuki Miyashita ◽  
...  
Keyword(s):  
Reaction Force ◽  
Force Analysis ◽  
Nonlinear Reaction ◽  
Breast Tissues

Reduction of ground-borne vibrations from rail lines on viaducts by means of elastic anti-vibration mats

2018 ◽  
Vol 233 (5) ◽  
pp. 550-565
Author(s):  
Caiyou Zhao ◽  
Wang Ping ◽  
Mengting Xing ◽  
Qiang Yi ◽  
Liuchong Wang
Keyword(s):  
High Speed ◽  
Reaction Force ◽  
Field Tests ◽  
Ground Vibration ◽  
Coupling System ◽  
Step Procedure ◽  
Measurement Results ◽  
Track Bridge ◽  
Bridge Bearing ◽  
The Impact

In this paper, the effectiveness of elastic anti-vibration mats in reducing ground-borne vibrations from rail viaducts is investigated by means of theoretical analysis and is validated by the results of field tests. A two-step procedure is adopted for analyzing the vehicle-track-bridge-soil coupling system. In the first step, the train-track-bridge-pier subsystem is considered, and the bridge-bearing reaction force is solved. In the second step, the pier-pile-soil subsystem is considered, and the ground vibration solution is obtained by applying the negative bridge-bearing reaction force to the pier top on a pier-pile-soil model. The accuracy of the presented model is then verified in comparison with in-situ measurement results. On the basis of this comparison, a parametric study on the impact of anti-vibration mats on ground-borne vibrations was investigated theoretically, and the effectiveness of elastic anti-vibration mats with the suggested optimal parameters was further validated by field tests. The results show that when the stiffness of the elastic anti-vibration mats is 1.5 MPa/m, ground vibration decreases significantly and the vertical rail displacement agrees with high-speed railway regulations.

Sensorimotor aspects of high-speed artificial gravity: II. The effect of head position on illusory self motion

2003 ◽  
Vol 12 (5-6) ◽  
pp. 283-289
Author(s):  
Fred W. Mast ◽  
Nathaniel J. Newby ◽  
Laurence R. Young
Keyword(s):  
Healthy Subjects ◽  
Horizontal Plane ◽  
High Speed ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Head Position ◽  
Artificial Gravity ◽  
Axis Of Rotation ◽  
Self Motion

The effects of cross-coupled stimuli on the semicircular canals are shown to be influenced by the position of the subject's head with respect to gravity and the axis of rotation, but not by the subject's head position relative to the trunk. Seventeen healthy subjects made head yaw movements out of the horizontal plane while lying on a horizontal platform (MIT short radius centrifuge) rotating at 23 rpm about an earth-vertical axis. The subjects reported the magnitude and duration of the illusory pitch or roll sensations elicited by the cross-coupled rotational stimuli acting on the semicircular canals. The results suggest an influence of head position relative to gravity. The magnitude estimation is higher and the sensation decays more slowly when the head's final position is toward nose-up (gravity in the subject's head x-z-plane) compared to when the head is turned toward the side (gravity in the subject's head y-z-plane). The results are discussed with respect to artificial gravity in space and the possible role of pre-adaptation to cross-coupled angular accelerations on earth.

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