Готові списки джерел за темами / Concentric and eccentric load

Добірка наукової літератури з теми "Concentric and eccentric load"

Автор: Grafiati
Опубліковано: 10 грудня 2022
Оновлено: 28 січня 2023

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Статті в журналах з теми "Concentric and eccentric load"

1

Merrigan, Justin J., James J. Tufano, Michael Falzone, and Margaret T. Jones. "Effectiveness of Accentuated Eccentric Loading: Contingent on Concentric Load." International Journal of Sports Physiology and Performance 16, no. 1 (January 1, 2021): 66–72. http://dx.doi.org/10.1123/ijspp.2019-0769.

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Анотація:
Purpose: To identify acute effects of a single accentuated eccentric loading (AEL) repetition on subsequent back-squat kinetics and kinematics with different concentric loads. Methods: Resistance-trained men (N = 21) participated in a counterbalanced crossover design and completed 4 protocols (sets × repetitions at eccentric/concentric) as follows: AEL65, 3 × 5 at 120%/65% 1-repetition maximum (1-RM); AEL80, 3 × 3 at 120%/80% 1-RM; TRA65, 3 × 5 at 65%/65% 1-RM; and TRA80, 3 × 3 at 80%/80% 1-RM. During AEL, weight releasers disengaged from the barbell after the eccentric phase of the first repetition and remained off for the remaining repetitions. All repetitions were performed on a force plate with linear position transducers attached to the barbell, from which eccentric and concentric peak and mean velocity, force, and power were derived. Results: Eccentric peak velocity (−0.076 [0.124] m·s−1; P = .01), concentric peak force (187.8 [284.4] N; P = .01), eccentric mean power (−145.2 [62.0] W; P = .03), and eccentric peak power (−328.6 [93.7] W; P < .01) during AEL65 were significantly greater than TRA65. When collapsed across repetitions, AEL65 resulted in slower eccentric velocity and power during repetition 1 but faster eccentric and concentric velocity and power in subsequent repetitions (P ≤ .04). When comparing AEL80 with TRA80, concentric peak force (133.8 [56.9] N; P = .03), eccentric mean power (−83.57 [38.0] W; P = .04), and eccentric peak power (−242.84 [67.3] W; P < .01) were enhanced. Conclusions: Including a single supramaximal eccentric phase of 120% 1-RM increased subsequent velocity and power with concentric loads of 65% 1-RM, but not 80% 1-RM. Therefore, AEL is sensitive to the magnitude of concentric loads, which requires a large relative difference to the eccentric load, and weight releasers may not need to be reloaded to induce performance enhancement.
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2

Taber, Christopher B., Jared R. Morris, John P. Wagle, and Justin J. Merrigan. "Accentuated Eccentric Loading in the Bench Press: Considerations for Eccentric and Concentric Loading." Sports 9, no. 5 (April 27, 2021): 54. http://dx.doi.org/10.3390/sports9050054.

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Анотація:
This study examined the effects of accentuated eccentric loading (AEL) on bench press velocities across a spectrum of concentric and eccentric loads. Ten strength trained men (bench press one-repetition maximum (1-RM): 124.3 ± 19.4 kg; relative strength ratio: 1.5 ± 0.2 kg∙body mass−1) participated. Subjects completed bench press repetitions using concentric loads from 30% to 80% 1-RM in 10% increments in each experimental session. The AEL protocols were implemented using 100% (AEL100) and 110% 1-RM (AEL110) loads during the eccentric action, while the eccentric load remained the same as the concentric for traditional loading (TRAD). Multilevel models analyzed the effects of each AEL protocol on concentric velocities across concentric loads (p < 0.05). Faster concentric velocities were observed at 30% 1-RM and 80% 1-RM with AEL100 compared to TRAD (p ≤ 0.05) but this effect was reduced for individuals moving the barbell through a greater displacement. Additionally, AEL110 presented a greater change in velocity from 30% to 80% 1-RM than TRAD (p ≤ 0.05). The AEL100 protocol resulted in faster concentric velocities throughout concentric loads of 30–80% 1-RM, but AEL110 may have been too great to elicit consistent performance enhancements. Thus, the efficacy of AEL at various concentric loads is dependent on the eccentric loading and barbell displacement.
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3

Smajla, Darjan, Darjan Spudić, and Nejc Šarabon. "Influence of Load and Phase of Contraction on Lateral Symmetries in Flywheel Squats." Symmetry 13, no. 1 (January 11, 2021): 111. http://dx.doi.org/10.3390/sym13010111.

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Анотація:
Assessment of lateral symmetries (LS) of lower limbs has been widely investigated. However, there are no studies about LS during exposure to high eccentric and concentric loads during flywheel (FW) squats. A total of 422 young, physically active participants performed squats on an FW device with different equidistant loads (0.05, 0.125 and 0.2 kg∙m2). The mean and peak force of the left and right leg were assessed for the concentric and eccentric contaction phase. LS values were calculated for each load and phase of squat. Our results showed that the absolute mean and peak force of the concentric and eccentric phase of contraction had excellent reliability, while LS values were more reliable when eccentric force was used for their calculation. Mean and peak forces were increased with the higher FW load. In general, we found a decrease in LS values in the concentric phase of contraction with the higher load. Moreover, values of LS are similar to a wide range of other functional movements. Nevertheless, symmetrical force application during squatting on a FW device should be satisfied regardless of the FW load. Due to the large sample size, our results are valuable as a reference point when athletes are evaluated during training.
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4

Armstrong, Richard, Vasilios Baltzopoulos, Carl Langan-Evans, Dave Clark, Jonathan Jarvis, Claire Stewart, and Thomas O’Brien. "An investigation of movement dynamics and muscle activity during traditional and accentuated-eccentric squatting." PLOS ONE 17, no. 11 (November 1, 2022): e0276096. http://dx.doi.org/10.1371/journal.pone.0276096.

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Анотація:
Introduction Accentuated-eccentric loading (AEL) takes advantage of the high force producing potential of eccentric muscle contractions, potentially maximising mechanical tension within the muscle. However, evidence is lacking on how AEL squatting may load the involved musculature, limiting scientifically justified programming recommendations. The purpose of this study was to investigate the effects of concentric and eccentric loads on joint loading and muscle activity of the lower limbs. Methods Resistance trained males performed traditional squatting (20–100% of concentric one-repetition maximum [1RM]) and AEL squatting with eccentric loads (110–150% of 1RM) provided by a novel motorised isotonic resistance machine (Kineo). Kinetics and kinematics of the hip, knee, and ankle joints were collected, with electromyography from the gluteus maximus, vastus lateralis, biceps femoris, and gastrocnemius medialis. A secondary cohort underwent a kinematic and electromyography analysis of squatting technique to compare Kineo and back and front barbell squatting. Results Knee joint peak eccentric moments occurred at 120% 1RM (P = 0.045), with no further increase thereafter. As eccentric load increased, the time course of moment development occurred earlier in the eccentric phase. This resulted in a 37% increase in eccentric knee extensor work from the 80% 1RM trial to the 120% 1RM trial (P<0.001). Neither hip nor ankle joints displayed further change in kinetics as eccentric load increased above 100% 1RM. Electromyographic activity during traditional squatting was ~15–30% lower in all eccentric trials than in concentric trials for all muscles. EMG plateaued between a load of 80–100% 1RM during the eccentric trials and did not increase with AEL. No significant differences in kinematics were found between Kineo and barbell squatting. Conclusions The knee extensors appear to be preferentially loaded during AEL squatting. The greater work performed during the eccentric phase of the squat as eccentric load increased suggests greater total mechanical tension could be the cause of adaptations from AEL. Our data suggest that AEL should be programmed with a load of 120% of 1RM. Further studies are needed to confirm the longer-term training effects of AEL.
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5

García-Ramos, Amador, Francisco Luis Pestaña-Melero, Alejandro Pérez-Castilla, Francisco Javier Rojas, and Guy Gregory Haff. "Differences in the Load–Velocity Profile Between 4 Bench-Press Variants." International Journal of Sports Physiology and Performance 13, no. 3 (March 1, 2018): 326–31. http://dx.doi.org/10.1123/ijspp.2017-0158.

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Анотація:
Purpose: To compare the load–velocity relationship between 4 variants of the bench-press (BP) exercise. Methods: The full load–velocity relationship of 30 men was evaluated by means of an incremental loading test starting at 17 kg and progressing to the individual 1-repetition maximum (1RM) in 4 BP variants: concentric-only BP, concentric-only BP throw (BPT), eccentric-concentric BP, and eccentric-concentric BPT. Results: A strong and fairly linear relationship between mean velocity (MV) and %1RM was observed for the 4 BP variants (r2 > .96 for pooled data and r2 > .98 for individual data). The MV associated with each %1RM was significantly higher in the eccentric-concentric technique than in the concentric-only technique. The only significant difference between the BP and BPT variants was the higher MV with the light to moderate loads (20–70%1RM) in the BPT using the concentric-only technique. MV was significantly and positively correlated between the 4 BP variants (r = .44–.76), which suggests that the subjects with higher velocities for each %1RM in 1 BP variant also tend to have higher velocities for each %1RM in the 3 other BP variants. Conclusions: These results highlight the need for obtaining specific equations for each BP variant and the existence of individual load–velocity profiles.
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Balsalobre-Fernández, Carlos, and Kristof Kipp. "Use of Machine-Learning and Load–Velocity Profiling to Estimate 1-Repetition Maximums for Two Variations of the Bench-Press Exercise." Sports 9, no. 3 (March 16, 2021): 39. http://dx.doi.org/10.3390/sports9030039.

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Анотація:
The purpose of the current study was to compare the ability of five different methods to estimate eccentric–concentric and concentric-only bench-press 1RM from load–velocity profile data. Smith machine bench-press tests were performed in an eccentric–concentric (n = 192) and a concentric-only manner (n = 176) while mean concentric velocity was registered using a linear position transducer. Load–velocity profiles were derived from incremental submaximal load (40–80% 1RM) tests. Five different methods were used to calculate 1RM using the slope, intercept, and velocity at 1RM (minimum velocity threshold—MVT) from the load–velocity profiles: calculation with individual MVT, calculation with group average MVT, multilinear regression without MVT, regularized regression without MVT, and an artificial neural network without MVT. Mean average errors for all methods ranged from 2.7 to 3.3 kg. Calculations with individual or group MVT resulted in significant overprediction of eccentric–concentric 1RM (individual MVT: difference = 0.76 kg, p = 0.020, d = 0.17; group MVT: difference = 0.72 kg, p = 0.023, d = 0.17). The multilinear and regularized regression both resulted in the lowest errors and highest correlations. The results demonstrated that bench-press 1RM can be accurately estimated from load–velocity data derived from submaximal loads and without MVT. In addition, results showed that multilinear regression can be used to estimate bench-press 1RM. Collectively, the findings and resulting equations should be helpful for strength and conditioning coaches as they would help estimating 1RM without MVT data.
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Park, Ju-Hyung, Seung-Jea Lee, Ho-Jin Shin, and Hwi-Young Cho. "Influence of Loads and Loading Position on the Muscle Activity of the Trunk and Lower Extremity during Squat Exercise." International Journal of Environmental Research and Public Health 19, no. 20 (October 18, 2022): 13480. http://dx.doi.org/10.3390/ijerph192013480.

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Анотація:
This study aimed to investigate the effect of the load and bar position on trunk and lower extremity muscle activity during squat exercise. High bar back squats (HBBS) and low bar back squats (LBBS) were performed in random order at 50%, 60%, and 70% loads of one repetition maximum by 28 experienced healthy adult men who had been performing squats for at least one year. Before the experiment, the maximal voluntary contraction of the vastus medialis, vastus lateralis, rectus femoris, biceps femoris, rectus abdominis, transverse abdominis, external oblique, and erector spinae muscles was measured by means of surface electromyography. In addition, eccentric and concentric exercises were performed for 3 s each to measure the muscle activity. There was a significant difference in muscle activity according to the load for all muscles in the eccentric and concentric phases (p < 0.05), indicating that muscle activity increased as the load increased. In addition, in the comparison between HBBS and LBBS, significant differences were shown in all lower extremity muscles and all trunk muscles except for the external oblique in the concentric phase according to the bar position (p < 0.05). HBBS showed a higher muscle activity of the lower extremity in the eccentric and concentric phases than in LBBS, while LBBS showed a higher muscle activity of the trunk muscle in the eccentric and concentric phases than in HBBS (p < 0.05). HBBS requires more force in the lower extremity than LBBS and is particularly advantageous in strengthening the muscular strength of the quadriceps. In contrast, LBBS requires more muscle activity in the trunk than HBBS and is more effective in carrying heavier loads because of the advantage of body stability. This study suggests that rehabilitation experts apply the bar position and load as important variables affecting the intensity and method of training for target muscle strengthening of the lower extremities and trunk.
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8

Pestaña-Melero, Francisco Luis, G. Gregory Haff, Francisco Javier Rojas, Alejandro Pérez-Castilla, and Amador García-Ramos. "Reliability of the Load–Velocity Relationship Obtained Through Linear and Polynomial Regression Models to Predict the 1-Repetition Maximum Load." Journal of Applied Biomechanics 34, no. 3 (June 1, 2018): 184–90. http://dx.doi.org/10.1123/jab.2017-0266.

Повний текст джерела
Анотація:
This study aimed to compare the between-session reliability of the load–velocity relationship between (1) linear versus polynomial regression models, (2) concentric-only versus eccentric–concentric bench press variants, as well as (3) the within-participants versus the between-participants variability of the velocity attained at each percentage of the 1-repetition maximum. The load–velocity relationship of 30 men (age: 21.2 [3.8] y; height: 1.78 [0.07] m, body mass: 72.3 [7.3] kg; bench press 1-repetition maximum: 78.8 [13.2] kg) were evaluated by means of linear and polynomial regression models in the concentric-only and eccentric–concentric bench press variants in a Smith machine. Two sessions were performed with each bench press variant. The main findings were: (1) first-order polynomials (coefficient of variation: 4.39%–4.70%) provided the load–velocity relationship with higher reliability than the second-order polynomials (coefficient of variation: 4.68%–5.04%); (2) the reliability of the load–velocity relationship did not differ between the concentric-only and eccentric–concentric bench press variants; and (3) the within-participants variability of the velocity attained at each percentage of the 1-repetition maximum was markedly lower than the between-participants variability. Taken together, these results highlight that, regardless of the bench press variant considered, the individual determination of the load–velocity relationship by a linear regression model could be recommended to monitor and prescribe the relative load in the Smith machine bench press exercise.
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9

Walker, Simon, Joanne Trezise, Guy Gregory Haff, Robert U. Newton, Keijo Häkkinen, and Anthony J. Blazevich. "Increased fascicle length but not patellar tendon stiffness after accentuated eccentric-load strength training in already-trained men." European Journal of Applied Physiology 120, no. 11 (August 9, 2020): 2371–82. http://dx.doi.org/10.1007/s00421-020-04462-x.

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Анотація:
Abstract Purpose This study examined whether additional external load during the eccentric phase of lower limb strength training exercises led to greater adaptations in knee extensor strength, muscle architecture, and patellar tendon properties than traditional concentric–eccentric training in already-trained men. Methods Twenty-eight men accustomed to strength training were randomized to undertake 10 weeks of supervised traditional (TRAD) or accentuated eccentric loading (AEL) or continue their habitual unsupervised (CON) strength training. TRAD and AEL trained 2∙week−1 with a six-repetition maximum (RM) session and a ten-RM session. TRAD used the same external load in both concentric and eccentric phases, while AEL used 40% greater load during the eccentric than concentric phase. Tests were performed at pre- and post-training, including: maximum unilateral isokinetic (30°·s−1) concentric, eccentric and isometric torques by isokinetic dynamometry, unilateral isometric ramp contractions with muscle–tendon ultrasound imaging to measure tendon stiffness and hysteresis, and resting vastus lateralis and medialis fascicle angle and length measured by extended-field-of-view ultrasound. Results After training, both TRAD and AEL significantly increased maximum concentric and isometric torque (p < 0.05), but only AEL increased eccentric torque (AEL: + 10 ± 9%, TRAD: + 4 ± 9%) and vastus lateralis (AEL: + 14 ± 14%, TRAD: + 1 ± 10%) and medialis (AEL: + 19 ± 8%, TRAD: + 5 ± 11%) fascicle length. Conclusion Both TRAD and AEL increased maximum knee extensor strength but only AEL increased VL and VM fascicle length. Neither training program promoted changes in fascicle angle or changes in patellar tendon properties in our already-trained men.
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Ritter, Ophélie, Laurie Isacco, Mark Rakobowchuk, Nicolas Tordi, Davy Laroche, Malika Bouhaddi, Bruno Degano, and Laurent Mourot. "Cardiorespiratory and Autonomic Nervous System Responses to Prolonged Eccentric Cycling." International Journal of Sports Medicine 40, no. 07 (May 20, 2019): 453–61. http://dx.doi.org/10.1055/a-0783-2581.

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Анотація:
AbstractOffering large muscle benefits despite low metabolic demand, continuous eccentric exercise appears to be an interesting alternative to concentric exercise. Nevertheless, further knowledge is needed about prolonged eccentric exercise. This work sought to investigate the cardiovascular responses to prolonged constant-load eccentric compared to concentric cycling. Ten healthy males performed two 45-min exercise sessions of either concentric or eccentric cycling separated by a month and matched for heart rate during the first 5 min of exercise. Cardiorespiratory, autonomic nervous system and vascular responses were assessed at rest, and during exercise and recovery. During cycling, oxygen uptake, cardiac output and systolic blood pressure were similar but heart rate and diastolic blood pressure were greater whereas stroke volume was lower during eccentric than concentric cycling (118±21 vs. 104±10 bpm; 77±9 vs. 65±8 mmHg; 122±12 vs. 135±13 mL). Baroreflex and noradrenaline concentration were altered during eccentric cycling, and after eccentric exercise, vascular tone was greater than after concentric cycling. We observed increased cardiovascular strain and altered baroreflex activity during eccentric compared with concentric exercise, suggesting eccentric cycling triggers greater sympathetic activity.
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Більше джерел

Дисертації з теми "Concentric and eccentric load"

1

Duhig, Steven J. "Hamstring strain injury: Effects of high speed running, kicking and concentric versus eccentric strength training on injury risk and running recovery." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/110637/1/Steven_Duhig_Thesis.pdf.

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Анотація:
The hamstring strain injury is a common and problematic injury within sports that involve high-speed running and kicking. This program of research has provided novel insights regarding the relationship between high speed running volumes and hamstring injuries, the effects of kicking on risk factors for hamstring strain and the muscular adaptations induced by concentric and eccentric hamstring exercises.
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2

Lawrence, Michael A. "Effects of elastic resistance on concentric force, concentric power, and eccentric velocity during the bench press." CardinalScholar 1.0, 2010. http://liblink.bsu.edu/uhtbin/catkey/1567419.

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Elastic bands are becoming more popular in strength and power training. Although increases in strength and power have been anecdotally reported with high loads of elastic resistance, there is no research on large band tensions and their effects on force and power variables. The purpose of this study was to quantify peak concentric force, peak concentric power and peak eccentric velocity produced by the subject when using differing levels of elastic resistance (0%, 20%, 50% and 75% of the total load being elastic resistance) in the bench press. Seven experienced male powerlifters and body builders participated in this study. Prior to subject testing all elastic bands were calibrated for force output throughout the bench press range of motion. Each subject performed a single repetition maximum press to determine the total correct testing load (85% of maximum press). The subjects then performed four presses with various elastic band resistances, each having the total equivalent weight of 85% of the subject’s maximal press weight at lockout. Dependent variables were peak concentric force, peak concentric power, and peak eccentric velocity as produced by the subject. A one-way ANOVA was used to determine the differences among the four levels of elastic resistance (ER) used in the study (α = 0.05). Compared to the baseline condition (2123.6 ± 499.9N), significantly lower average peak concentric force was observed with ER of 75% (1451.2 ± 151.0N, 31.9% decrease) (p = .010) and with an ER of 50% (1781.1 ± 174.3N, 16.4% decrease) (p = .052). When compared with baseline peak concentric power (702.6 ± 274.6W), higher peak power was observed in all band trials: 20% (895.2 ± 187.7W, 27.4% increase), 50% (972.5 ± 189.8W, 38.4% increase) and 75% (979.6 ± 171.0W, 39.4% increase) (p = .009; p = .007; p = .033, respectively). There was no significant difference in peak concentric power in any ER trials. No significant differences (p = .080) were seen in peak eccentric velocity. Therefore ER loads of 20, 50 and 75% provide greater stimuli for producing peak concentric power than no ER, with only a 20% load of ER maintaining the same peak concentric force production as baseline. ER loads of 50 and 75% may not be as effective a stimuli as free weights when the training objective is to increase force production.
School of Physical Education, Sport, and Exercise Science
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3

Gault, Mandy Lucinda. "Adaptations of older adults to concentric and eccentric endurance exercise." Thesis, University of Chichester, 2010. http://eprints.chi.ac.uk/813/.

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Анотація:
The first aim was to examine in older adults the acute physiological effects of eccentric exercise (i.e. downhill treadmill walking, DW: -10% gradient, 30-min) at a self-selected walking speed. The secondary aim was to examine in older adults the effects of a 12-week concentric (level treadmill walking, LW: 0% gradient) and eccentric (downhill treadmill walking, DW: -10% gradient) endurance exercise intervention (30-min, 3x week) at a self-selected walking speed (SSWS, re-evaluated every 4-weeks) on the functional and physiological adaptations. Participants were randomly assigned to an exercise group (LW: 0=13 or DW: n=IS). Eighteen participants (8 LWand 10 DW) completed the 12-week intervention. Wearing the Cosmed K4b2 portable metabolic system had no effect on performance and physiological responses during the I-mile Rockport Fitness Walking Test (Study I).
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4

Deighan, Martine Annette. "The development of concentric and eccentric leg and arm strength." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393145.

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5

Kellis, Eleftherios. "Muscle activation and joint loading during isokinetic eccentric and concentric exercise." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321116.

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6

Kudiarasu, Christine. "Effects of eccentric versus concentric resistance training in adults with Type 2 Diabetes." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2297.

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Анотація:
The benefits of resistance training for people with Type 2 diabetes (T2D) are well documented; however, the effects of different muscle contraction types (e.g. eccentric, concentric) on physiological outcomes for this population are still unclear. This study investigated the effects of eccentric (ECC) versus concentric (CON) resistance training on blood markers, muscle strength, physical functional performance and body composition. Eighteen adults with T2D (Age: 64.8 ± 9.0 y; BMI: 30.3 ± 4.1 kg/m2) were randomly assigned to either an ECC (n = 9) or a CON (n = 9) group. Participants performed 2 or 3 sets of 10 eccentric (5-s) or concentric (2-s) contractions of eight upper and lower body resistance exercises, twice a week for 12 weeks. Training intensity gradually increased from 10 to 100% of 1-repetition maximum concentric strength (1-RM) for the ECC group and from 50 to 100% of 1-RM strength for the CON group, based on the 1-RM at baseline. Blood markers (glucose, insulin, HbA1c, HOMA2-IR, cholesterol, triglycerides, HDL and LDL), muscle strength (1- RM), body composition (dual-energy x-ray absorptiometry), and physical functional performance tests consisting of 6-min walk (6MWT), chair rise (CR), timed up-and-go (TUG), and balance were measured before and after the intervention, and the changes were compared between groups. Significant differences in the improvement between the ECC and CON group were found for 1-RM strength for bicep curl (ECC: 11%, CON: 27%), calf raise (ECC: 37%, CON: 68%) and abdominal crunch (ECC: 22%, CON: 42%) exercises, hip circumference (ECC: -1%, CON: -5%) and SF-36 pain measures (ECC: 6%, CON: -1%). Muscle strength significantly increased more for the CON group (27–68%) than the ECC group (12–37%) which was likely due to greater combined total load lifted in the CON (143,262 ± 57,972 kg) than the ECC group (111,678 ± 51,225 kg). Significant improvements (p < 0.05) were also found in the ECC group for the 6MWT (56.8 ± 2.2 m), TUG (-0.8 ± 0.3 s) and CR (-1.8 ± 1.4 s), while the CON group significantly improved the 6MWT (63.4 ± 12.0 m) and CR (-2.3 ± 1.6 s). Total equilibrium balance increased by 7.0% in the ECC group and 4.3% in the CON group. Body composition improved similarly for both groups including significant reductions in total fat mass (ECC: -2.0 ± 1.3 kg, CON: -2.2 ± 1.2 kg) and significant increase in total lean mass (ECC: 1.8 ± 0.7 kg, CON: 2.0 ± 0.2 kg). No significant changes were found in blood markers for both groups. These results showed that ECC training performed at lower intensities (RPE: 4.1 ± 2.1) was as effective as CON training for improving physical functional performance, strength and body composition. These findings suggest that focusing on eccentric contractions in resistance training is beneficial and well-tolerated in adults with T2D.
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7

Fischer, Stephen Michael. "METABOLIC DIFFERENCES BETWEEN A BOUT OF ECCENTRIC, CONCENTRIC, AND TRADITIONAL RESISTANCE EXERCISE." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1479465117642973.

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8

Shaw, I., BS Shaw, JF Cilliers, and DT Goon. "Influence of visual feedback on knee extensor isokinetic concentric and eccentric peak torque." African Journal for Physical, Health Education, Recreation and Dance, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001651.

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Abstract Isokinetic normative data can be invaluable in identifying an individual’s strengths and weaknesses, and thus lead to a more effective use of the individual’s time to minimise or overcome his weaknesses while maintaining or improving existing strength. However, visual feedback (VF) may significantly affect the result of isokinetic testing, resulting in erroneous conclusions if not accounted for. Additionally, the previous use of VF to obtain increased strength values has resulted in inconsistent findings. The purpose of this study was to examine the effect of VF on concentric and eccentric knee extensor peak torque. Twenty-two sedentary, college-aged male and female volunteers were assigned to either Group 1 (n = 11) or Group 2 (n = 11) to either perform knee extensor concentric-eccentric (con-ecc) isokinetic testing with VF or without VF (no-VF) using a crossover method. After a one-week rest, the two groups underwent knee extensor con-ecc isokinetic testing using the alternative testing condition. Each test consisted of five maximal knee extensor con-ecc isokinetic testing contractions at 60° per second on the Cybex Norm system. The data indicated significant (p < 0.05) differences in the concentric peak torque of Group 1, Group 2 and Combined Group following VF when compared to no-VF. The eccentric peak torque of Group 1, Group 2 and Combined Group was found not to be significantly different following VF when compared to no-VF. Further, no significant interaction effect as a result of the different groups was found. Visual feedback of torque output can improve maximum voluntary concentric contraction in isokinetic dynamometry, but not maximum voluntary eccentric contraction. It is thus recommended that VF should be consistently provided during isokinetic testing, since it can also be used to help detect and correct errors in performance as well as derive reinforcement from correct performances.
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Razmislevičius, Darius. "Ekscentrinio koncentrinio prieškrūvio poveikis nesportuojančių asmenų vegetacinių sistemų rodikliams didelio intensyvumo darbe." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060516_103637-32433.

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The hypothesis. We supposed the fatigue and its residual phenomena generated by eccentric concentric load to have a different effect on the changes in vegetative indices during exercise of high aerobic intensity in particular. The aim of the research was to establish the effect of eccentric concentric pre-load on the changes in vegetative indices during exercise of high intensity. The tasks set were as follows: 1. To estimate the residual effect of eccentric pre-load on the changes in vegetative indices during exercise of high intensity. 2. To estimate the residual effect of eccentric-concentric pre-load on the changes in vegetative indices during exercise of high intensity. 3. To compare the residual effect of eccentric and eccentric-concentric pre-load on the vegetative indices, biochemical indices of blood during exercise of high intensity. The subjects were 9 unsportsman persons, who gave their informed consent to take part in the experiments within the present study. They were distributed to two eksperimental groups. The first group carried out eccentric pre-load and the second group carried out eccentric-concentric pre-load. The methods used were as follows: changes in the values of VO2, VCO2, heart rate (HR) and Ve indices of the subjects were established applying the test of continuously increased load and the test of constant load when pedalling the veloergometer. After testing blood of the subjects to establish lactate and Creatin-Kinase (CK) concentration in... [to full text]
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Raue, Ulrika. "Effects of concentric vs eccentric resistance training on skeletal muscle adaptations in humans." Virtual Press, 2001. http://liblink.bsu.edu/uhtbin/catkey/1221284.

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The Beothuk Indians were an extinct group of Amerinds who were among the earliest founders of Newfoundland. In literature, the Beothuk were described as perhaps being phenotypically more similar to Europeans than Asians (Gatschet 1890, Lloyd 1875, 1876a, Marshall 1996). In this research, mitochondrial DNA (mtDNA) analysis was performed on a Beothuk individual in order to determine his haplotype and, perhaps, shed light on the origins of the Beothuk.For this analysis, a tooth of Nonosabasut, a Beothuk chief who died in 1819 was loaned from the Royal Museum of Scotland. Ancient DNA was extracted from 172 mg of dentin from the tooth. The DNA was cut with two blunt-end restriction enzymes, RsaI and HaeIII. Double-stranded DNA adapters were ligated to the blunt ends. A single adapter was used to amplify the resulting fragments using PCR. In this manner, two libraries of the DNA were created that could be readily reamplified using a small amount of the PCR product. mtDNA type was determined by amplifying specific regions and performing Restriction Fragment Length Polymorphism analysis and sequencing. It was determined that the Beothuk individual had a 9-bp deletion at nucleotide position (np) 8272, an Alul restriction site at np 5176, and heteroplasmy for a HincII restriction site at np 13,259, indicating that the Beothuk individual falls into the Native American Haplogroup B. Haplogroup B is not present in modern Siberian populations, whereas the remaining Native American mtDNA haplogroups are. It has been hypothesized that Haplogroup B arrived in the Americas at a different time than haplogroups A, C, D, and X, about 16,000-13,000 YBP (Years Before Present) (Starikovskaya et al. 1998). Haplogroup B can be found in some modern Taiwanese, Japanese, Korean, Evenk, and other Asian populations.Sequencing of the D-Loop region revealed a G to A transition at np 16303. To our knowledge, this transition was never previously reported in a Native American. This transition has been reported in Tibetans, Koreans, Hans, and Japanese, all considered to be southeast Asian Causacoids (Torroni et al. 1993b, 1994b). This transition, also frequently described in the Caucasian Haplogroup H, is especially prevalent in Spain and among the Basque. It is described as a root haplotype of Haplogroup H whose expansion was estimated to be between 12,300-13,200 YBP (Torroni et al. 1998). This time estimate coincides with the expansion of Haplogroup B. One possible explanation for this transition may be some admixture of the Beothuk with a Caucasian population.
School of Physical Education
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Книги з теми "Concentric and eccentric load"

1

Sundararaj, Palanimuthu (Ravi). High strength concrete columns under eccentric load. Ottawa: National Library of Canada, 1992.

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2

Yang, L. Behaviour of masonry columns of geometric section subjected to eccentric axial load. Manchester: UMIST, 1995.

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3

Noël, Jean-Marc A. Modes of vibration in an ideal fluid between infinite soft and rigid concentric and eccentric circular cylindrical boundaries. Sudbury, Ont: Laurentian University, 1994.

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4

100 concentric dialectics of eccentric fish antics. AuthorHouse, 2016.

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5

Dowson, Martin Neil. Concentric and eccentric muscle actions and their relationship with sprint performance. 1995.

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6

National Aeronautics and Space Administration (NASA) Staff. Eccentric and Concentric Muscle Performance Following 7 Days of Simulated Weightlessness. Independently Published, 2018.

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7

C, Hayes Judith, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Program., eds. Eccentric and concentric muscle performance following 7 days of simulated weightlessness. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1992.

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8

Concentric and eccentric muscle function in normal and chronically sprained ankles: Prevention implications. 1993.

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9

1958-, Wang Ru, ed. Behaviour of masonry cavity walls under vertical eccentric loads. Edmonton, Alta., Canada: Dept. of Civil Engineering, University of Alberta, 1996.

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10

Cross-education following single-limb eccentric and concentric training on the Biodex isokinetic dynamometer. 1994.

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Частини книг з теми "Concentric and eccentric load"

1

Campione, Giuseppe, and Sidney Mindess. "Size Effect in Compression of High Strength Fibre Reinforced Concrete Cylinders Subjected to Concentric and Eccentric Loads." In Materials for Buildings and Structures, 86–91. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527606211.ch13.

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2

Mai, A. D., M. N. Sheikh, and M. N. S. Hadi. "Investigation on the Performance of Non-uniformly, Discretely and Continuously CFRP Confined Square Reinforced Concrete Columns under Concentric and Eccentric loads." In Lecture Notes in Civil Engineering, 857–65. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-3303-5_78.

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3

Müller, Alison L., and Naranjan S. Dhalla. "Differences in Concentric Cardiac Hypertrophy and Eccentric Hypertrophy." In Cardiac Adaptations, 147–66. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-5203-4_8.

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4

Mitchell, R. A., R. L. Seifarth, and C. P. Reeve. "Eccentric Load Sensitivity of Force Sensors." In Mechanical Problems in Measuring Force and Mass, 275–81. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4414-5_32.

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5

Thibodeau, Nicholas, Alan Lloyd, and Hassan Fatemi. "Concentric and Eccentric Material Characterization of Polyurethane Disc Bridge Bearings." In Lecture Notes in Civil Engineering, 343–57. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0656-5_29.

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6

Baron, R., N. Bachl, R. Petschnig, A. Engel, S. Liebenberger, and L. Prokop. "Metabolic Response of Concentric and Eccentric Musclework in Female Handball Players." In Advances in Ergometry, 415–18. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76442-4_59.

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7

Koller, A., E. Müller, E. Artner-Dworzak, C. Haid, W. Schobersberger, B. Puschendorf, and E. Raas. "Metabolic Changes Following Concentric and Eccentric Exercise in Trained and Untrained Subjects." In Advances in Ergometry, 406–9. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-76442-4_57.

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8

Wang, Jun, Zhiming Hao, Y. H. Yin, Pingan Shi, and Bing Xu. "Analysis of Pre-Tightened Bolt Connections under Eccentric Load." In Computational Mechanics, 313. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75999-7_113.

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9

Venkatarama Reddy, B. V., V. Suresh, and K. S. Nanjunda Rao. "Behaviour of Cement Stabilised Rammed Earth Walls Under Concentric and Eccentric Gravity Loading." In Earthen Dwellings and Structures, 293–303. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-5883-8_26.

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10

Ritwik Maiti, Gargi Das, and Prasanta Kumar Das. "A Qualitative Assessment of Different Regimes During Concentric and Eccentric Discharge a Silo." In Fluid Mechanics and Fluid Power – Contemporary Research, 1617–26. New Delhi: Springer India, 2016. http://dx.doi.org/10.1007/978-81-322-2743-4_154.

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Тези доповідей конференцій з теми "Concentric and eccentric load"

1

Amir, Yosef, Saravanakumar Iyyanar, Aravind Devali, and Muniratnam Kumar. "Bending Effect in Concentric Bolted Joints Under Transverse Load." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63201.

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Bending stress calculation in eccentric bolted joints is a well-known process in the design of bolted joints. However, in a concentric bolted joint with transverse load, the existence of bending stress is generally not considered as critical. But in reality, there is a possibility of catastrophic failure of the bolt occurring in a concentric bolted joint as a result of the bending stress even before the joint looseness or before the bolt fracture under tension. The aim of this paper is to propose a closed form solution to predict the potential risk of this failure that could be developed particularly at moderate preload of the bolt. Three concentric bolted joint cases with M12, M10 and M8 with transverse load and external tension load were investigated; FEA and experimental results validated the closed form calculation.
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Piquer Vicent, Ana, David Hernández-Figueirido, and Carmen Ibáñez Usach. "Concrete-filled round-ended steel tubular stub columns under concentric and eccentric loads." In 12th international conference on ‘Advances in Steel-Concrete Composite Structures’ - ASCCS 2018. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/asccs2018.2018.7197.

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In the past, many works to study the mechanical behaviour of concrete filled steel tubular (CFST) stub columns have been conducted. Some of the applications of these composite columns oblige to meet higher requirements of ductility and load-bearing capacity. Traditionally, circular and rectangular tubes have been employed but recently new cross-sectional shapes of these composite columns are being designed and investigated with the aim of optimizing their mechanical behaviour. In this line, concrete-filled round-ended steel tubular columns (CFRT) have appeared as an alternative. However, the number of experimental programs to characterize their mechanical response is still scarce. In order to contribute to the test results database, in this paper an experimental study of 9 concrete-filled round-ended steel tubular stub columns is presented. All the specimens were designed with the same cross-sectional round-ended shape and have the same dimensions. In this program, both normal and high-strength concrete were employed as infill. During the tests, the columns were subjected to axial compression loads but under different eccentricities. The influence of eccentricity and concrete strength on the ultimate load bearing capacity of the concrete-filled round-ended steel tubular are discussed. Besides, the combined action of both components in this type of concrete-filled tubes as well as the effect of the concrete infill are studied.
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Zhang, Sumei, Jie Chen, Zhenfeng Huang, Xiongxiong Zhang, and Lanhui Guo. "Behavior of innovative T-shaped multi-partition steel-concrete composite columns under concentric and eccentric compressive loadings." In 12th international conference on ‘Advances in Steel-Concrete Composite Structures’ - ASCCS 2018. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/asccs2018.2018.7004.

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T-shaped multi-partition steel-concrete composite column, composed of several concrete-filled rectangular steel hollow sections, is considered as an innovative composite member with the ability to accommodate neighboring wall thickness with great easiness. This paper intends to study the behavior of this innovative composite member under concentric and eccentric compressive loadings. A finite element (FE) analysis model accounting for the influences of confinement effects, geometric and material nonlinearities is developed using the program ABAQUS. The ultimate strength and load-strain responses predicted from the analysis are validated against the test results in the experiments conducted by the authors. The comparisons indicate that the FE model reasonably estimates the responses of the concentrically and eccentrically loaded T-shaped multi-partition steel-concrete composite columns. The verified model is then utilized to numerically investigate the working mechanism of the columns. The load distribution between the infilled concrete and the steel tubes and the stress distribution of the concrete during the loading process are analyzed. Moreover, parametric studies are performed to investigate the behavior of T-shaped multi-partition steel-concrete composite columns under different loadings. The studied parameters include steel to concrete area ratio, concrete compressive strength, steel yield strength and load eccentricity. Combined with the experimental results, FE analysis and parametric studies, the design recommendations for T-shaped multi-partition steel-concrete composite columns under different loadings are proposed.
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Bao, Juntao, Jianming Gong, Shantung Tu, Yuesheng Li, and Yanfei Qiu. "Life Prediction of the Tapered Pipe With High Temperature and High Pressure by Finite Element Methods." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/creep2007-26171.

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Tapered pipe used in the main steam pipelines, which operated at high temperature and high pressure, including concentric tapered pipe and eccentric tapered pipe, they are sources of weakness in the piping system serviced in the power stations and the chemical plants, and creep is the significant reason that caused their failure. Creep damage analyses are carried out for these two kinds of tapered pipes by introducing user subroutine based on the modified Karchanov-Rabotnov constitutive equations into finite element program ABAQUS, then the effects of bending moments and internal pressure to the serviced life of the components are investigated by comparing four group of calculated results under different loads, the results indicated that eccentric tapered pipe is more inclinable to broken than concentric tapered pipe under the same conditions, so it is not recommended to use the eccentric tapered pipe in the piping system. The bending moments will accelerate the components’ failure, so it is necessary to take some advantages to reduce the bending moments near the tapered pipe, on the other hand, the life of the tapered pipe will decrease quickly with the internal pressure increasing, so the control of the operated pressure is important to ensure the serviced life of the pipelines.
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Wang, Sheng, Kangbin Lei, Xilian Luo, Kiwamu Kase, Elia Merzari, and Hisashi Ninokata. "Cylindrical Couette Flow of a Rarefied Gas From Macro- to Micro-Scales." In ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78359.

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The cylindrical Couette flow of a rarefied gas from macro- to micro-scales, in the case where the inner cylinder is rotating whereas the outer cylinder is at rest, is extensively investigated by direct simulation Monte Carlo (DSMC) code incorporated with a Volume-CAD software. The generalized soft sphere (GSS) model is applied to an intermolecular collision calculation. The diffuse reflection model and Cercignani-Lampis-Lord (CLL) model are used to model the molecule-surface interaction by considering the accommodation coefficients on inner cylinder (ACI hereafter) and outer cylinder (ACO hereafter) separately. The contents in this paper include following three aspects: I the flow field characteristics and force and torque on inner cylinder for eccentric Couette flow between different scales with same non-dimensional parameters (accommodation coefficients, eccentricity-clearance ratio, Knudsen number and Reynolds number) are compared; the flow field characteristics for different scales are same; with the increase of the scale, the total force on the inner cylinder increases slightly, while the torque is proportional to the scale; II the velocity profiles in concentric Couette flow under different non-dimensional parameters are studied; the result shows that the phenomenon of inverted velocity profile in the concentric Couette flow is only induced by a smooth outer cylinder; the non-dimensional tangential velocity, as well as its gradient is high at low Reynolds number; the Knudsen number has great impact on the tangential velocity profile, and the velocity profile may not be inverted in the case of low Knudsen number; III the flow field characteristics in eccentric Couette flow under different non-dimensional parameters are obtained; the recirculation zone may not appear when Knudsen number is high; the position of its center may be different depending on Reynolds number; with the increase of Reynolds number, the compressibility effect becomes important; stratified distribution of the density becomes obvious at low Knudsen number.
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Fujioka, Yasuo. "Behavior and Mechanisms of Bolt Self-Loosening Under Transverse Load Due to Vibrations of a Washer Along an Arc." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66830.

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Self-loosening mechanisms of a bolt were investigated by Finite Element Method, under the assumption of a twist at the center of a circular joined structure in which the bolt was set along a certain pitch circle. In this structure, the bolt is loosened by combining the translational and rotational external loads. In the case of a large pitch circle structures in which self-loosening occurs, the directions of friction shear forces on the threads were along concentric circles; however, the instantaneous center of rotation was located one-side near the thread surface, and the center was eccentric with the axis of the bolt. If the radius of the pitch circle is set smaller, the instantaneous center of rotation moves closer to the center of the bolt, and finally reaches to the same position at the center of the bolt. On the other hand, the directions of friction shear forces on pitch diameter of one thread were calculated theoretically using the inclination and friction on a pressure flank. The results were in good agreement with FE analysis. By considering these mechanisms, it was estimated that the number of occurrence of self-loosening in one vibration cycle changes at the border when the diameter value of the pitch circle equals that of the screw threads. If the diameter of the pitch circle becomes smaller than that of the screw threads, the number changes from two to one. With the exception of torsional center-fastened structures, since the pitch circle is very small, self-loosening of general joined structures will occur twice in one vibration cycle.
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Zhu, W. D., and X. F. Wang. "Modeling and Control of an Infinitely Variable Speed Converter With Application to Wind Turbines." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86074.

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Traditional transmission in wind turbine applications has a constant output-to-input speed ratio, which needs a power converter to regulate the current frequency that can be fed into the grid. Different types of continuously variable transmission (CVT) have been developed for vehicle and wind turbine applications, which can generate constant-frequency current without using a power converter in a wind turbine. An infinitely variable speed converter (IVSC) is a specific type of CVT that can achieve a zero speed ratio and transmit a large torque at a low speed ratio. An IVSC with drivers that convert an eccentric motion of cams to a concentric motion of the output shaft through one-way bearings is introduced, and an active control system with a combined feedback and feed forward control that can automatically adjust the eccentricity of the outer cams to control the speed ratio of the transmission is developed. The kinematic model of the IVSC is derived and fitted by a polynomial function to serve as the feed forward function in the control law. The feedback control is used to reduce the system error. A dynamic model of the IVSC is derived to investigate the effect of the dynamic load on the input and output speeds. Static and dynamic tests were conducted to validate the kinematic model of the IVSC. The variation of the average output speed per revolution of the output shaft is 0.56% with respect to the desired output speed in the simulation and 0.91% in the experiments.
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Queiroz de Oliveira, Sabrina, Barbarah Hemilly de Souza Valente, Dayane Azevedo Pereira, Letícia Pavoni dos Passos, Paloma Morgade Zaccaro, and Luciano Matos Chicayban. "Blood flow restriction in the postoperative of anterior cruciate ligament reconstruction." In 7th International Congress on Scientific Knowledge. Biológicas & Saúde, 2021. http://dx.doi.org/10.25242/8868113820212394.

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Blood flow restriction is a physical therapy technique that consists of promoting increased strength and muscle hypertrophy, similar to protocols with high loads. It can be used in the prevention and rehabilitation of injuries, health promotion and improvement in sports performance, as in the postoperative period of anterior cruciate ligament reconstruction, accelerating functional recovery. To identify the effects of blood flow restriction in patients undergoing anterior cruciate ligament reconstruction. Through a systematic review of the literature, randomized clinical trials were selected according to the highest PEDro score. The search involved the PEDro database, PubMed, using the following terms: bloodflow restriction, anterior cruciate ligament, anteriorcruciate ligament injury and BFR exercise, published between 2000 and 2021. Six RCTs were selected: three did not demonstrate benefits in relation to atrophy, strength, volume and activation of the quadriceps muscle during blood flow restriction, when used through isometric, concentric and eccentric exercises, with progressive loads or without loads. In two other RCTs, there were positive results in relation to the aforementioned parameters, where freeexercises were performed, with body resistance and sessions with occlusive stimuli and occlusion release. Finally, one of the RCTs showed equal improvement in both groups in quadriceps hypertrophy and strength; and regarding the use of flow restriction inone of the groups, there was a reduction in joint pain and effusion. Blood flow restriction has shown contradictory results in relation to atrophy, decreased pain, effusion and asymmetry of the quadriceps muscle in patients undergoing anterior cruciate ligament reconstruction.
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Berthold, Martin, Hervé Morvan, Richard Jefferson-Loveday, Benjamin C. Rothwell, and Colin Young. "Multiphase CFD Modeling of External Oil Flow From a Journal Bearing." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-77130.

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High loads and bearing life requirements make journal bearings a potential choice for use in high power, epicyclic gearboxes in jet engines. Particularly in a planetary configuration the kinematic conditions are complex. With the planet gears rotating about their own axis and orbiting around the sun gear, centrifugal forces generated by both motions interact with each other and affect the external flow behavior of the oil exiting the journal bearing. Computational Fluid Dynamics (CFD) simulations using the Volume of Fluid (VoF) method are carried out in ANSYS Fluent [1] to numerically model the two-phase flow behavior of the oil exiting the bearing and merging into the air surrounding the bearing. This paper presents an investigation of two numerical schemes that are available in ANSYS Fluent to track or capture the air-oil phase interface: the geometric reconstruction scheme and the compressive scheme. Both numerical schemes are used to model the oil outflow behavior in the most simplistic approximation of a journal bearing: a representation, rotating about its own axis, with a circumferentially constant, i.e. concentric, lubricating gap. Based on these simplifications, a three dimensional (3D) CFD sector model with rotationally periodic boundaries is considered. A comparison of the geometric reconstruction scheme and the compressive scheme is presented with regards to the accuracy of the phase interface reconstruction and the time required to reach steady state flow field conditions. The CFD predictions are validated against existing literature data with respect to the flow regime, the direction of the predicted oil flow path and the oil film thickness. Based on the findings and considerations of industrial requirements, a recommendation is made for the most suitable scheme to be used. With a robust and partially validated CFD model in place, the model fidelity can be enhanced to include journal bearing eccentricity. Due to the convergent-divergent gap and the resultant pressure field within the lubricating oil film, the outflow behavior can be expected to be very different compared to that of a concentric journal bearing. Naturally, the inlet boundary conditions for the oil emerging from the journal bearing into the external environment must be consistent with the outlet conditions from the bearing. The second part of this paper therefore focuses on providing a method to generate appropriate inlet boundary conditions for external oil flow from an eccentric journal bearing.
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AZOUZ, IDIR, SIAMAK SHIRAZI, ALI PILEHVARI, and J. AZAR. "Numerical simulation of turbulent flow in concentric and eccentric annuli." In 23rd Fluid Dynamics, Plasmadynamics, and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1993. http://dx.doi.org/10.2514/6.1993-3106.

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Звіти організацій з теми "Concentric and eccentric load"

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STUDY ON LOAD-DEFLECTION RELATIONSHIP OF RECYCLED SELF-COMPACTING CONCRETE FILLED STEEL TUBULAR COLUMNS SUBJECTED TO ECCENTRIC COMPRESSION. The Hong Kong Institute of Steel Construction, September 2019. http://dx.doi.org/10.18057/ijasc.2019.15.3.5.

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EXPERIMENTAL AND THEORETICAL RESEARCH ON RCFT BEAM-COLUMNS FABRICATED WITH Q420B HIGH-STRENGTH STEEL SUBJECTED TO ECCENTRIC LOAD. The Hong Kong Institute of Steel Construction, December 2020. http://dx.doi.org/10.18057/ijasc.2020.16.4.1.

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CALCULATION METHOD OF ULTIMATE LOAD BEARING CAPACITY OF CONCRETE FILLED STEEL TUBULAR LATTICE COLUMNS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.095.

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Анотація:
To investigate the influence of eccentricity ratio and slenderness ratio on the mechanical properties of eccentric compressed concrete filled steel tubular (CFST) lattice column, the ultimate bearing capacity tests of 20 K shape arrangement lacing strip of four-tube CFST columns were conducted. Based on the stress-strain relationship of CFST and the influence of shear deformation, the equilibrium equation of the mid-section is established and a numerical method for the ultimate bearing capacity of CFST lattice column is proposed. The slenderness reduction coefficient calculation model and equivalent slenderness ratio formula of CFST lattice column are established. Combined with the numerical results and the slenderness ratio reduction coefficient calculation model, the formula of slenderness ratio reduction coefficient is put forward. The comparison between theoretical analysis and experimental results shows that the calculation method of elastic-plastic ultimate bearing capacity of CFST lattice column proposed in this paper is quite accurate. The research outcomes can provide a reference for the application of CFST lattice column and revision of current specifications.
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NUMERICAL AND THEORETICAL STUDIES ON DOUBLE STEEL PLATE COMPOSITE WALLS UNDER COMPRESSION AT LOW TEMPERATURES. The Hong Kong Institute of Steel Construction, December 2021. http://dx.doi.org/10.18057/ijasc.2021.17.4.6.

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Анотація:
Double steel plate composite walls (DSCWs) with several unique types of connectors have been implemented to protect offshore oil exploration platforms from concentric forces caused by ice in the Arctic region. This paper investigates the compressive perfor-mance of DSCWs with interlocked J-hooks and overlapped headed studs at low temperatures ranging from 20 ℃ to -80 ℃ with nonlinear finite element models (FEMs). The intricate geometric size of the concrete, multiple interactions of the concrete with the connectors, and material nonlinearities of the concrete have been thoroughly simulated. The reasonable consistency between the results of the monotonic tests and finite element analysis (FEA) on nine DSCWs with interlocked J-hooks and seven DSCWs with overlapped headed studs indicates that the FEMs can effectively predict the compressive performance of the DSCWs at low temper-atures. On the basis of the validated FEMs, the effects of the horizontal and vertical spacing of the connectors on the compressive performance of the DSCWs are studied. Finally, theoretical models of the load-displacement curves are developed to reveal the compressive response of DSCWs at low temperatures with different types of connectors, taking into account the restraining effect of steel plates on the inner concrete and the local buckling of steel plates. Compared with previous tests and FEA, the developed theoretical models have reasonable consistency for the load-displacement curves of DSCWs at low temperatures.
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