Journal articles: 'Concentric Reducer'

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Subaschandar, N. "Computational Study of Fluid Flow Inside a Concentric Reducer." MATEC Web of Conferences 54 (2016): 11001. http://dx.doi.org/10.1051/matecconf/20165411001.

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Sang, Z. F., and G. E. O. Widera. "Stress and Strength Analysis of Concentric Reducers Consisting of Plates." Journal of Pressure Vessel Technology 110, no. 2 (May 1, 1988): 217–24. http://dx.doi.org/10.1115/1.3265592.

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This paper presents a new kind of piping component—a concentric reducer consisting of plates. Authors performed experimental and elastic, elastic-plastic analyses on five test models having different structural parameters. The elastic stress distribution under hydraulic test pressure, the extension of the plastic region under higher than operating loads and the results of bursting tests are also reported on. Results indicate that under test pressure the maximum stress occurs at the inside of the junction area between the small end of the reducer and the small end tube. Yield and final burst also occurs at this area under higher than operating pressure. Based on the results of the analysis, it can be concluded that the reducer is safe and reliable.

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Singh, C. D., S. K. Dhua, M. Kumar, A. K. Jha, T. Mrinal, K. Sharma, R. R. Abhyuday, and Y. Kumar. "Metallurgical Investigation of a Prematurely Failed Concentric Reducer Tube Used in a Hot-Rolling Mill." Journal of Failure Analysis and Prevention 7, no. 4 (August 15, 2007): 292–301. http://dx.doi.org/10.1007/s11668-007-9048-y.

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Ulfah, Nurul, Rahman Hakim, and Michael Tri Adelitho. "Rancang Bangun Jig & Fixture Untuk Pipe Fitting Steel Concentric Reducer Pada Mesin Bevel Pipa." Jurnal Poli-Teknologi 19, no. 2 (November 5, 2020): 145–50. http://dx.doi.org/10.32722/pt.v19i2.2742.

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Pang, Seung-Ki, and Hye-Rin Ahn. "Evaluation of Flow Characteristics in Water Supply Pipes Shielding Electromagnetic Pulse of 100 dB with Concentric and Eccentric Reducers." Transactions of the Korea Society of Geothermal Energy Engineers 13, no. 1 (March 1, 2017): 1–6. http://dx.doi.org/10.17664/ksgee.2017.13.1.001.

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Deev, A. V., T. Rasheed, M. C. Welsh, M. M. K. Khan, and M. G. Rasul. "Measurement of instantaneous flow velocities in a concentric reducer using Particle Image Velocimetry: Study of scale deposition." Experimental Thermal and Fluid Science 33, no. 6 (September 2009): 1003–11. http://dx.doi.org/10.1016/j.expthermflusci.2009.05.001.

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Aghaei-Lasboo, Anahita, Katherine Inoyama, Adam S. Fogarty, Jonathan Kuo, Kimford J. Meador, Jessica J. Walter, Scheherazade T. Le, Kevin D. Graber, Babak Razavi, and Robert S. Fisher. "Tripolar concentric EEG electrodes reduce noise." Clinical Neurophysiology 131, no. 1 (January 2020): 193–98. http://dx.doi.org/10.1016/j.clinph.2019.10.022.

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Kay, Anthony D., and Anthony J. Blazevich. "Concentric muscle contractions before static stretching minimize, but do not remove, stretch-induced force deficits." Journal of Applied Physiology 108, no. 3 (March 2010): 637–45. http://dx.doi.org/10.1152/japplphysiol.01135.2009.

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The effects of concentric contractions and passive stretching on musculotendinous stiffness and muscle activity were studied in 18 healthy human volunteers. Passive and concentric plantar flexor joint moment data were recorded on an isokinetic dynamometer with simultaneous electromyogram (EMG) monitoring of the triceps surae, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction. The subjects then performed six 8-s ramped maximal voluntary concentric contractions before repeating both the passive and concentric trials. Concentric moment was significantly reduced (6.6%; P < 0.01), which was accompanied by, and correlated with ( r = 0.60–0.94; P < 0.05), significant reductions in peak triceps surae EMG amplitude (10.2%; P < 0.01). Achilles tendon stiffness was significantly reduced (11.7%; P < 0.01), but no change in gastrocnemius medialis muscle operating length was detected. The subjects then performed three 60-s static plantar flexor stretches before being retested 2 and 30 min poststretch. A further reduction in concentric joint moment (5.8%; P < 0.01) was detected poststretch at 90% of range of motion, with no decrease in muscle activity or Achilles tendon stiffness, but a significant increase in muscle operating length and decrease in tendon length was apparent at this range of motion ( P < 0.05). Thirty minutes after stretching, muscle activity significantly recovered to pre-maximal voluntary concentric contractions levels, whereas concentric moment and Achilles tendon stiffness remained depressed. These data show that the performance of maximal concentric contractions can substantially reduce neuromuscular activity and muscle force, but this does not prevent a further stretch-induced loss in active plantar flexor joint moment. Importantly, the different temporal changes in EMG and concentric joint moment indicate that a muscle-based mechanism was likely responsible for the force losses poststretch.

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Lee, Dae-Young, Jongwoo Kim, Ji-Suk Kim, Changyeob Baek, Gunwoo Noh, Do-Nyun Kim, Keri Kim, Sungchul Kang, and Kyu-Jin Cho. "Anisotropic Patterning to Reduce Instability of Concentric-Tube Robots." IEEE Transactions on Robotics 31, no. 6 (December 2015): 1311–23. http://dx.doi.org/10.1109/tro.2015.2481283.

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Banks, R. E., and W. K. R. Musgrave. "The operation of concentric-tube distillation columns under reduced pressure." Journal of Applied Chemistry 6, no. 5 (May 4, 2007): 214–18. http://dx.doi.org/10.1002/jctb.5010060504.

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Aagaard, P., E. B. Simonsen, J. L. Andersen, S. P. Magnusson, J. Halkjær-Kristensen, and P. Dyhre-Poulsen. "Neural inhibition during maximal eccentric and concentric quadriceps contraction: effects of resistance training." Journal of Applied Physiology 89, no. 6 (December 1, 2000): 2249–57. http://dx.doi.org/10.1152/jappl.2000.89.6.2249.

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Despite full voluntary effort, neuromuscular activation of the quadriceps femoris muscle appears inhibited during slow concentric and eccentric contractions. Our aim was to compare neuromuscular activation during maximal voluntary concentric and eccentric quadriceps contractions, hypothesizing that inhibition of neuromuscular activation diminishes with resistance training. In 15 men, pretraining electromyographic activity of the quadriceps muscles [vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF)] was 17–36% lower during slow and fast (30 and 240°/s) eccentric and slow concentric contractions compared with fast concentric contractions. After 14 wk of heavy resistance training, neuromuscular inhibition was reduced for VL and VM and was completely removed for RF. Concurrently, electromyographic activity increased 21–52, 22–29, and 16–32% for VL, VM, and RF, respectively. In addition, median power frequency decreased for VL and RF. Eccentric quadriceps strength increased 15–17%, whereas slow and fast concentric strength increased 15 and 8%, respectively. Pre- and posttraining median power frequency did not differ between eccentric and concentric contractions. In conclusion, quadriceps motoneuron activation was lower during maximal voluntary eccentric and slow concentric contractions compared with during fast concentric contraction in untrained subjects, and, after heavy resistance training, this inhibition in neuromuscular activation was reduced.

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Bortoletto, M., C. Rodella, R. Salvador, P. C. Miranda, and C. Miniussi. "Reduced Current Spread by Concentric Electrodes in Transcranial Electrical Stimulation (tES)." Brain Stimulation 9, no. 4 (July 2016): 525–28. http://dx.doi.org/10.1016/j.brs.2016.03.001.

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Li, Cheng Yu, and Yao Jie Guo. "Mechanical Behavior of Concrete Filled Steel Tubular out Stiffener Ring Connections with Reduced Beam Section." Advanced Materials Research 243-249 (May 2011): 865–70. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.865.

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The past study indicates that, when the space joint of concentric annular-stiffer is loaded, stress concentration may generate at corner. The destruction usually concentrates in the joint region, and then cannot generate “strong joint”. To change this unfavorable characteristic, the reduced beam section connection is adopted. Through oriented reducing beam section, the plastic region is formed, which can achieve the aim of “weak beam, strong joint”. After the simulation and analysis to space joints on outer concentric annular-stiffer which are processed by reduced beam section, the loading conditions of the joints are obviously improved in the following aspects: (1) the stress distribution on annular plate is smoothed obviously, the degree of stress concentration on corner is significantly decreased; (2) to assure plastic hinge firstly appear on the beam end but not the ring surface, we can change the size of ring plate, length of beam and the flange weaken degree; (3)the joint stiffness does not decrease during the stage of elastic loading; (4)under repeated loading, the joint region has little change and the plastic expansion on the ring surface is not obvious. Above all, reducing beam section can improve the mechanical properties of CFST-steel beam space joints with outer concentric annular-stiffer, thus the “strong joint” requirement could be fulfilled.

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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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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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Kay, Anthony D., and Anthony J. Blazevich. "Isometric contractions reduce plantar flexor moment, Achilles tendon stiffness, and neuromuscular activity but remove the subsequent effects of stretch." Journal of Applied Physiology 107, no. 4 (October 2009): 1181–89. http://dx.doi.org/10.1152/japplphysiol.00281.2009.

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The effects of isometric contractions and passive stretching on muscle-tendon mechanics and muscle activity were studied in 16 healthy human volunteers. First, peak concentric and passive ankle joint moment data were recorded on an isokinetic dynamometer with electromyographic monitoring of the triceps surae; real-time motion analysis of the lower leg and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Second, the subjects performed six 8-s maximal voluntary isometric contractions (MVICs) before repeating the passive and active trials. Although there was no decrease in isometric joint moment after MVICs, peak concentric moment was significantly reduced (11.5%, P < 0.01). This was accompanied by, and correlated with ( r = 0.90, P < 0.01), significant reductions in peak triceps surae electromyographic amplitude (21.0%, P < 0.01). Achilles tendon stiffness (10.9%, P < 0.01) and passive joint moment (4.9%, P < 0.01) were also significantly reduced. Third, the subjects performed three 60-s static plantar flexor stretches before being retested 2 and 30 min after stretch. The stretch protocol caused no significant change in any measure. At 30 min after stretching, significant recovery in concentric moment and muscle activity was detected at dorsiflexed joint angles, while Achilles tendon stiffness and passive joint moment remained significantly reduced. These data show that the performance of MVICs interrupts the normal stretch-induced losses in active and passive plantar flexor joint moment and neuromuscular activity, largely because concentric strength and tendon properties were already affected. Importantly, the decrease in Achilles tendon stiffness remained 30 min later, which may be an important etiological factor for muscle-tendon strain injury risk.

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Bai, Yun Shan, Yi Jiang, and Dong Mo Zhou. "Analysis of Concentric Canister Wall Roughness Effect on Jet Flow Based on Fluid Dynamics." Applied Mechanics and Materials 252 (December 2012): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amm.252.3.

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Adopting concentric canister launchers (CCL), high temperature and high pressure environment of CCL is unfavorable for the missile launch. In addition to the gap between internal canister and external canister, injecting water for cooling are the main factor of impact the canister flow field, CCL’s rough wall is also a very important influence factor. In this paper, under the two working conditions of rough wall and smooth wall, use dynamic layering manner of moving mesh update method to simulate concentric canister missile launch process. The results reveal that rough wall has a great influence for pressure of concentric canister internal flow field, but the least influence for temperature. In practical engineering applications, need smooth surface material for smooth flow field exhaust when manufacturing concentric cylinder, but the non-concentric canister manufacturing of missile cold-launch canister, retain the rough wall can increase the pressure of the missile launch, this is conducive to missile launch, and also saves manufacturing costs, reduces processing procedures.

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Kang, Seok Hee, Yong Cheol Shin, Eun Young Hwang, Jong Ho Lee, Chang-Seok Kim, Zhiqun Lin, Seung Hyun Hur, Dong-Wook Han, and Suck Won Hong. "Engineered “coffee-rings” of reduced graphene oxide as ultrathin contact guidance to enable patterning of living cells." Materials Horizons 6, no. 5 (2019): 1066–79. http://dx.doi.org/10.1039/c8mh01381k.

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The generation of ultrathin nanotextured films in the form of micropatterns (i.e., concentric gradient rGO coffee rings) is effectively tailored, and these patterned rGO arrays can be utilized as promising cell-responsive templates.

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Zhang, Li, Yong-Chang Jiao, and Bo Chen. "Optimization of Concentric Ring Array Geometry for 3D Beam Scanning." International Journal of Antennas and Propagation 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/625437.

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Optimization of the element placement in a concentric ring array for three-dimensional (3D) beam scanning with minimum peak sidelobe levels (SLLs) is addressed in this paper. In order to achieve 3D beam scanning with the lowest peak SLL, both the radius and the element spacing of each ring are optimized. Moreover, the aperture size is a very important constraint for the array, since there is an upper limit for the aperture size of a given array in real-life environment. Hence, in our optimization design, the maximum radius of the concentric ring array is constrained. Through the optimization, the peak SLL of the optimal concentric ring array is about 6 dB lower than that of the uniform concentric ring array, but the directivity is reduced by only 0.3 dB.

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Burigo, Ricardo Lima, Robson Dias Scoz, Bruno Mazziotti de Oliveira Alves, Rubens Alexandre da Silva, Cesar Augusto Melo-Silva, Edgar Ramos Vieira, Rogerio Pessoto Hirata, and Cesar Ferreira Amorim. "Concentric and eccentric isokinetic hamstring injury risk among 582 professional elite soccer players: a 10-years retrospective cohort study." BMJ Open Sport & Exercise Medicine 6, no. 1 (November 2020): e000868. http://dx.doi.org/10.1136/bmjsem-2020-000868.

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Background/AimDifferent authors have tried to correlate the peak isokinetic torque values with the incidence of soccer match injuries. However, due to the wide variety of assessment testing protocols, such an inference becomes difficult. This study aimed to verify the capacity of an isokinetic test to establish injury risk reference values for hamstring strain injuries.MethodsA retrospective cohort study based on isokinetic data and clinical records from the last 10 years was conducted in 582 Brazilian elite-professional soccer players, who were subjected to the same isokinetic test protocol, machine, and tester. A Multivariate Logistic Regression Analysis for Complex Data Sampling was used to generate injury risk statistical indexes.ResultsMultivariate regression analysis of both legs provided important data to identify the cut-off values of Concentric Peak Torque (181.82 Newton/*metres), Concentric Work (236.23 watts) and Concentric Power (130.11 joules).ConclusionsThe injury risk indexes indicate that an increase of just one Newton unit in CPT (Concentric Peak Torque) and CJ (Concentric Power) above those cut-off values, can reduce the risk of future injuries by 2% and 2.7%, respectively.

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Fedorova, N. N., and M. M. Habibulina. "Evaluation of hormonal balance indicators in men with arterial hypertension in various types of left ventricular remodeling." Kazan medical journal 97, no. 3 (June 15, 2016): 323–27. http://dx.doi.org/10.17750/kmj2016-323.

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Aim. To evaluate features of the hormonal balance in men with hypertension with different types of left ventricular geometry.Methods. The study included 63 men (mean age 49.74±4.91 years) with II degree hypertension (the disease duration 6.03±3.64 years). In all patients the level of testosterone, estradiol, prolactin, thyroid-stimulating hormone in blood serum were determined and echocardiography was performed, which was done on the expert class machine PHILIPS iE33 (Netherlands).Results.. According to echocardiographic examination data concentric hypertrophy prevailed in the left ventricular hypertrophy structure - 33 (52.38%) patients, eccentric hypertrophy occured in 18 (28.57%), concentric remodeling - in 12 (19.04%) patients. When analyzing the hormonal profile of patients a significant difference in testosterone levels in patients with various types of the left ventricular remodeling was revealed. In the concentric left ventricular hypertrophy, testosterone levels were lowest, and in some patients were beyond the lower limit of the normal range. Estradiol level exceeded the reference range values in men with concentric type of hypertrophy. The estradiol content in the group of men with concentric left ventricular remodeling was significantly higher than in patients with eccentric hypertrophy (pConclusion. In patients with hypertension, concentric left ventricular hypertrophy (as compared with eccentric hypertrophy and concentric remodeling) occurs more often, it is accompanied by a decrease in total testosterone level in blood serum; timely correction of early androgen deficiency will allow to reduce the risk of cardiovascular complications.

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Iltaf, Asim, Massab Junaid, Fahd N. khan, and Azhar Hussain. "Microstructure, mechanical properties, residual stresses and texture analysis of Ti-5Al-2.5Sn alloy weldments obtained using electron beam of different oscillation patterns." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 17 (April 6, 2020): 3484–96. http://dx.doi.org/10.1177/0954406220916550.

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Electron beam welding was used for welding of Ti-5Al-2.5Sn alloy using three types of beam oscillation patterns, i.e. elliptical, concentric circles and arrow shape waveform. The influence of these patterns on microstructure, mechanical properties and residual stresses was investigated using optical microscopy, electron back scattered diffraction, scanning electron microscopy, microhardness measurement, residual stress measurement, impact testing, smooth and notch tensile testing. A partial martensitic transformation was observed in the fusion zone of all the three welding patterns. The fusion zone of arrow pattern weldment exhibited approximately 16% and 1.2% higher hardness than elliptical and concentric circles patterns, respectively. Owing to an improved texture of the basal and prismatic planes in the cross-weld direction, the arrow pattern showed improved strength, reduced tensile residual stresses than elliptical and concentric circles pattern. Elliptical pattern showed superior elongation characteristics as well as increased impact strength as compared to the arrow and concentric circle patterns.

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Gates, Phillip E., Christopher L. Gentile, Douglas R. Seals, and Demetra D. Christou. "Adiposity Contributes to Differences in Left Ventricular Structure and Diastolic Function with Age in Healthy Men." Journal of Clinical Endocrinology & Metabolism 88, no. 10 (October 1, 2003): 4884–90. http://dx.doi.org/10.1210/jc.2003-030673.

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Abstract We sought to examine the influence of adiposity in age-associated changes in the left ventricle (LV) in a cohort of 113 healthy men, aged 20–79 yr, by measuring LV structure and diastolic function (echocardiography), whole body composition, and regional adiposity (dual energy x-ray absorptiometry). Aging was associated with increased levels of adiposity, greater wall thickness to chamber radius ratio, LV concentric remodeling, and reduced LV diastolic function (all P < 0.05). Bivariate correlation analysis showed that mean LV wall thickness, a concentric LV morphology, and diastolic function were related to adiposity (r = −0.63 to 0.51; all P < 0.05). The relation between age and both mean LV wall thickness and concentric remodeling was reduced after controlling for percentage total body fat (by 38% and 54%, respectively), percentage abdominal fat (by 42% and 62%), and the abdominal/thigh fat ratio (by 35% and 46%). The diastolic function-age relation was reduced after controlling for percentage total body fat (by 35%), percentage abdominal fat (by 39%), and the abdominal/thigh fat ratio (by 29%). There were no apparent differences in the contribution of percentage total body fat, percentage abdominal fat, or abdominal/thigh fat to the association between age and LV structure/diastolic function. We conclude that increasing adiposity contributes to the LV remodeling/reduced diastolic function that occurs with aging in healthy men.

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Domínguez Cabrera, María del Pino. "El Registro Especial de Buques de Canarias." Revista Electrónica de Derecho de la Universidad de La Rioja (REDUR), no. 2 (November 5, 2018): 99. http://dx.doi.org/10.18172/redur.3850.

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Este trabajo aborda el estudio del Registro Especial de Buques y Empresas Navieras de Canarias (REBECA) como único segundo registro marítimo español. Se trata de un registro adicional al Registro Marítimo ordinario que reúne además las características de especial, público y administrativo, opcional, heterónomo, y selectivo. Más específicamente, concentra su atención en el objeto registral pues, como el título indica, se ocupa exclusivamente del Registro de Buques, pero no de la inscripción de las empresas marítimas o navieras, aunque la Ley de Puertos del Estado y de la Marina Mercante también contemple la inscripción de los empresarios navieros. Además, se examina el registro de embarcaciones y artefactos sin proceder a un análisis pormenorizado de las titularidades, cargas, gravámenes y limitaciones que encuentran cabida en el asiento registral practicado en el Registro Especial.

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Babault, Nicolas, Michel Pousson, Yves Ballay, and Jacques Van Hoecke. "Activation of human quadriceps femoris during isometric, concentric, and eccentric contractions." Journal of Applied Physiology 91, no. 6 (December 1, 2001): 2628–34. http://dx.doi.org/10.1152/jappl.2001.91.6.2628.

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Maximal and submaximal activation level of the right knee-extensor muscle group were studied during isometric and slow isokinetic muscular contractions in eight male subjects. The activation level was quantified by means of the twitch interpolation technique. A single electrical impulse was delivered, whatever the contraction mode, on the femoral nerve at a constant 50° knee flexion (0° = full extension). Concentric, eccentric (both at 20°/s velocity), and isometric voluntary activation levels were then calculated. The mean activation levels during maximal eccentric and maximal concentric contractions were 88.3 and 89.7%, respectively, and were significantly lower ( P < 0.05) with respect to maximal isometric contractions (95.2%). The relationship between voluntary activation levels and submaximal torques was linearly fitted ( P < 0.01): comparison of slopes indicated lower activation levels during submaximal eccentric compared with isometric or concentric contractions. It is concluded that reduced neural drive is present during 20°/s maximal concentric and both maximal and submaximal eccentric contractions. These results indicate a voluntary activation dependency on both tension levels and type of muscular actions in the human knee-extensor muscle group.

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Kay, Anthony D., and Anthony J. Blazevich. "Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length." Journal of Applied Physiology 106, no. 4 (April 2009): 1249–56. http://dx.doi.org/10.1152/japplphysiol.91476.2008.

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The effects of static stretch on muscle and tendon mechanical properties and muscle activation were studied in fifteen healthy human volunteers. Peak active and passive moment data were recorded during plantar flexion trials on an isokinetic dynamometer. Electromyography (EMG) monitoring of the triceps surae muscles, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Subjects performed three 60-s static stretches before being retested 2 min and 30 min poststretch. There were three main findings in the present study. First, peak concentric moment was significantly reduced after stretch; 60% of the deficit recovered 30 min poststretch. This was accompanied by, and correlated with ( r = 0.81 ; P < 0.01) reductions in peak triceps surae EMG amplitude, which was fully recovered at 30 min poststretch. Second, Achilles tendon length was significantly shorter during the concentric contraction after stretch and at 30 min poststretch; however, no change in tendon stiffness was detected. Third, passive joint moment was significantly reduced after stretch, and this was accompanied by significant reductions in medial gastrocnemius passive muscle stiffness; both measures fully recovered by 30 min poststretch. These data indicate that the stretching protocol used in this study induced losses in concentric moment that were accompanied by, and related to, reductions in neuromuscular activity, but they were not associated with alterations in tendon stiffness or shorter muscle operating length. Reductions in passive moment were associated with reductions in muscle stiffness, whereas tendon mechanics were unaffected by the stretch. Importantly, the impact on mechanical properties and neuromuscular activity was minimal at 30 min poststretch.

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Hernández-Davó, J. L., R. Sabido, M. Moya-Ramón, and A. J. Blazevich. "Load knowledge reduces rapid force production and muscle activation during maximal-effort concentric lifts." European Journal of Applied Physiology 115, no. 12 (October 3, 2015): 2571–81. http://dx.doi.org/10.1007/s00421-015-3276-8.

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Andersen, Ole Emil, Ole Bækgaard Nielsen, and Kristian Overgaard. "Early effects of eccentric contractions on muscle glucose uptake." Journal of Applied Physiology 126, no. 2 (February 1, 2019): 376–85. http://dx.doi.org/10.1152/japplphysiol.00388.2018.

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Muscle-damaging eccentric exercise impairs muscle glucose uptake several hours to days after exercise. Little, however, is known about the acute effects of eccentric exercise on contraction- and insulin-induced glucose uptake. This study compares glucose uptake rates in the first hours following eccentric, concentric, and isometric contractions with and without insulin present. Isolated rat extensor digitorum longus muscles were exposed to either an eccentric, concentric, or isometric contraction protocol, and muscle contractions were induced by electric stimulation that was identical between contraction protocols. In eccentric and concentric modes, length changes of 0.6 or 1.2 mm were used during contractions. Both contraction- and insulin-induced glucose uptake were assessed immediately and 2 h after contractions. Glucose uptake increased significantly following all modes of contraction and was higher after eccentric contractions with a stretch of 1.2 mm compared with the remaining contraction groups when assessed immediately after contractions [eccentric (1.2 mm) > eccentric (0.6 mm), concentric (1.2 mm), concentric (0.6 mm), isometric > rest; P < 0.05]. After 2 h, contraction-induced glucose uptake was still higher than noncontracting levels, but with no difference between contraction modes. The presence of insulin increased glucose uptake markedly, but this response was blunted by, respectively, 39–51% and 29–36% ( P < 0.05) immediately and 2 h after eccentric contractions stretched 1.2 mm compared with concentric and isometric contractions. The contrasting early effects of eccentric contractions on contraction- and insulin-induced glucose uptake suggest that glucose uptake is impaired acutely following eccentric exercise because of reduced insulin responsiveness.NEW & NOTEWORTHY This study shows that, in isolated rat muscle, muscle-damaging eccentric contractions result in a transient increase in contraction-induced glucose uptake compared with isometric and concentric contractions induced by identical muscle activation protocols. Furthermore, our results demonstrate that, in contrast, the insulin-stimulated glucose uptake is impaired immediately following muscle-damaging eccentric contractions.

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Chen, Hung Chien, Tzu Chen Hung, and Yi Feng Chen. "Numerical Analysis of Heat Transfer in the Concentric Heat Exchanger." Applied Mechanics and Materials 275-277 (January 2013): 572–75. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.572.

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The computational fluid dynamics (CFD) software is used to compute three-dimensional concentric heat exchanger in this research. In order to reduce the burden of the computational time, the concentric heat exchanger is simplified sector of 5° for the regular arrangement of internal shape. The working fluids for hot flow and cold flow are helium and molten salt individually. The arrangements for hot and cold flow paths within a heat exchanger is opposite. This study is mainly focused on the distribution of field for the two layers of concentric heat exchanger. The width of the flow channel as well as the length, pitch, thickness and angle of fin have been changing to analyze the effectiveness-NTU method. The results showed that the best heat transfer of fin thickness, angle, space, length, and flow channel are under 5mm, 5°, 8mm, 44mm, and 12mm, respectively.

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Teertstra, Peter M., M. Michael Yovanovich, and J. Richard Culham. "Natural Convection Measurements for a Concentric Spherical Enclosure." Journal of Heat Transfer 128, no. 6 (December 15, 2005): 580–87. http://dx.doi.org/10.1115/1.2188476.

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An experimental test program is described for the measurement of natural convection for an isothermal, heated sphere centrally located in an isothermal, cooled spherical enclosure. A transient test method is used in a reduced pressure environment to provide data for a wide range of Rayleigh number, from the limiting case of laminar boundary layer convection to the diffusive limit. Tests are performed using a fixed outer diameter for four different inner sphere diameters, resulting in diameter ratios in the range 1.5⩽do∕di⩽4.8. The data are in excellent agreement with the exact solution for the conductive limit and are shown to be bounded by a model for the isolated, isothermal sphere.

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Perentis, Panagiotis A., Evgenia D. Cherouveim, Vassiliki J. Malliou, Nikos V. Margaritelis, Panagiotis N. Chatzinikolaou, Panayiotis Koulouvaris, Charilaos Tsolakis, Michalis G. Nikolaidis, Nickos D. Geladas, and Vassilis Paschalis. "The Effects of High-Intensity Interval Exercise on Skeletal Muscle and Cerebral Oxygenation during Cycling and Isokinetic Concentric and Eccentric Exercise." Journal of Functional Morphology and Kinesiology 6, no. 3 (July 16, 2021): 62. http://dx.doi.org/10.3390/jfmk6030062.

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The aim of the present study was to study the effects of cycling and pure concentric and pure eccentric high-intensity interval exercise (HIIE) on skeletal muscle (i.e., vastus lateralis) and cerebral oxygenation. Twelve healthy males (n = 12, age 26 ± 1 yr, body mass 78 ± 2 kg, height 176 ± 2 cm, body fat 17 ± 1% of body mass) performed, in a random order, cycling exercise and isokinetic concentric and eccentric exercise. The isokinetic exercises were performed on each randomly selected leg. The muscle and the cerebral oxygenation were assessed by measuring oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation index. During the cycling exercise, participants performed seven sets of seven seconds maximal intensity using a load equal to 7.5% of their body mass while, during isokinetic concentric and eccentric exercise, they were performed seven sets of five maximal muscle contractions. In all conditions, a 15 s rest was adopted between sets. The cycling HIIE caused greater fatigue (i.e., greater decline in fatigue index) compared to pure concentric and pure eccentric isokinetic exercise. Muscle oxygenation was significantly reduced during HIIE in the three exercise modes, with no difference between them. Cerebral oxygenation was affected only marginally during cycling exercise, while no difference was observed between conditions. It is concluded that a greater volume of either concentric or eccentric isokinetic maximal intensity exercise is needed to cause exhaustion which, in turn, may cause greater alterations in skeletal muscle and cerebral oxygenation.

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Chen, Young Long, Yung Chi Chang, and Yu Ling Zeng. "An Opportunistic Large Array Concentric Geographic Routing Algorithm with a Relay Node in Wireless Sensor Networks." Applied Mechanics and Materials 764-765 (May 2015): 838–42. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.838.

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Wireless sensor networks (WSNs) are a group of wireless sensor nodes, those sensor nodes with sensing and monitoring of environmental information. Energy consumption is an important topic; the node's power is limited. Therefore, we proposed an Opportunistic Large Array Concentric Geographic Routing Algorithm (OLACGRA) to reduce the node’s energy consumption and analysis the characteristic of energy model. The sink position of our proposed OLACGRA is at the center of concentric topology architecture. The source node wants to transmit data that it needs to calculate the distance between source node and sink node. If this distance bigger than threshold value, we use the multi-hop manner. Otherwise, source node transmits data to sink node directly. Simulation results show that our proposed algorithm can effectively reduce the node’s energy consumption.

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Klein, Franziska J., Stephen Bell, K. Elisabeth Runte, Robert Lobel, Takamuru Ashikaga, Lilach O. Lerman, Martin M. LeWinter, and Markus Meyer. "Heart rate-induced modifications of concentric left ventricular hypertrophy: exploration of a novel therapeutic concept." American Journal of Physiology-Heart and Circulatory Physiology 311, no. 4 (October 1, 2016): H1031—H1039. http://dx.doi.org/10.1152/ajpheart.00301.2016.

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Lowering the heart rate is considered to be beneficial in heart failure (HF) with reduced ejection fraction (HFrEF). In a dilated left ventricle (LV), pharmacological heart rate lowering is associated with a reduction in LV chamber size. In patients with HFrEF, this structural change is associated with better survival. HF with preserved ejection fraction (HFpEF) is increasingly prevalent but, so far, without any evidence-based treatment. HFpEF is typically associated with LV concentric remodeling and hypertrophy. The effects of heart rate on this structural phenotype are not known. Analogous with the benefits of a low heart rate on a dilated heart, we hypothesized that increased heart rates could lead to potentially beneficial remodeling of a concentrically hypertrophied LV. This was explored in an established porcine model of concentric LV hypertrophy and fibrosis. Our results suggest that a moderate increase in heart rate can be used to reduce wall thickness, normalize LV chamber volumes, decrease myocardial fibrosis, and improve LV compliance. Our results also indicate that the effects of heart rate can be titrated, are reversible, and do not induce HF. These findings may provide the rationale for a novel therapeutic approach for HFpEF and its antecedent disease substrate. Listen to this article’s corresponding podcast at http://ajpheart.podbean.com/e/heart-rate-modeling/ .

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Zhai, Zhenfeng, Weifeng Ye, Fei Xia, and Lele Yang. "Analytical Solution for Wave Diffraction by a Concentric Three-Cylinder System near a Vertical Wall." Mathematics 9, no. 16 (August 7, 2021): 1876. http://dx.doi.org/10.3390/math9161876.

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In this study, a semi-analytical model was developed to study wave diffraction around a concentric three-cylinder system near a wall based on linear potential theory. As a critical element, the target problem is transformed into bidirectional incident wave diffraction around two concentric structures based on the image principle and an analytical solution is obtained through eigenfunction expansion combined with a matching technique and Graf’s addition theorem. The validity of the proposed model was verified by comparing its results to known values. Parametric studies on porosity, annular spacing, incident angle, space between the structure and wall, and water depth were performed. The hydrodynamic loads and free-surface elevations in the system were calculated and compared to those reported in existing works on impermeable and permeable cylinders near a wall. The results indicate that the wave loads and run-ups on the exterior cylinder increase significantly based on the existence of the wall. However, based on the presence of an exterior porous protective structure, a significantly reduced influence of the wall on the interior cylinder can be observed. Considering the widespread use of concentric circular structures in ocean engineering, it is essential to conduct study on the hydrodynamic performance of concentric systems near walls, which can provide useful information for the design of marine structures.

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Dey, Anupam, and Rajarshi Sanyal. "Single layer miniaturized ultra-thin FSS with five closely spaced bands." International Journal of Microwave and Wireless Technologies 11, no. 08 (May 3, 2019): 797–805. http://dx.doi.org/10.1017/s1759078719000370.

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AbstractThis Paper reveals a novel single layer five band frequency selective surface (FSS). Novelties of the proposed FSS lie in its five closely spaced stop bands at 2.4, 3.38, 4.82, 6.32, and 7.75 GHz as well as the reduced single layer structural thickness (0.0016 λ0) and the miniaturized unit cell size (0.0656 λ0) at lower resonant frequency as compared to the existing multiband FSS. The unit cell structure consists of six octagonal concentric interconnected loops. Adjacent loop interconnection technique reduces the cell size by more than 44%. Furthermore, arrow-shaped rings are also introduced on each corner of the outermost octagonal loop, and using this technique approximate 23% cell miniaturization can be achieved. In addition, the proposed FSS exhibits excellent angular stability.

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Khan, Muhammad Ammar, Jing-Fu Bao, Fei-Hong Bao, and Xin Zhou. "Concentric Split Aluminum with Silicon-Aluminum Nitride Annular Rings Resonators." Micromachines 10, no. 5 (April 30, 2019): 296. http://dx.doi.org/10.3390/mi10050296.

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This paper presents a novel approach of annular concentric split rings microelectromechanical resonators with tether configuration to reduce anchor loss and gives very high-quality factor (Q) 2.97 Million based on FEA (Finite Element Analysis) simulation. The operating frequencies of these resonators are 188.55 MHz to 188.62 MHz. When the proposed SR (square rectangle) hole shaped one dimensional phononic crystal (1D PnC), and two dimensional phononic crystal (2D PnC) structure consist of very wide and complete band gaps is applied to novel design rings MEMS resonators, the quality factor (Q) further improved to 19.7 Million and 1750 Million, respectively, by using the finite element method. It is also observed that band gaps become closer by reducing the value of filling fraction, and proposed SR PnC gives extensive peak attenuation. Moreover, harmonic response of ring resonator is verified by the perfect match layers (PML) technique surrounded by resonators with varying width 1.5λ, and 3λ effectively reduce the vibration displacement.

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Hawkey, Adam, and Alexander Dallaway. "Application of acute whole-body vibration and lower-body exercise: effects on concentric torque in lower-limb muscles." Biomedical Human Kinetics 12, no. 1 (January 1, 2020): 157–65. http://dx.doi.org/10.2478/bhk-2020-0020.

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SummaryStudy aim: With contrary evidence regarding the effectiveness of acute whole-body vibration training (WBVT) on sporting performance, the current study examined WBVT’s effect on concentric torque of the quadriceps (Q) and hamstrings (H).Material and methods: Following ethical approval, 11 male team sport players (age: 22.9 ± 3.3 yrs, height: 1.80 ± 0.07 m, mass: 82.5 ± 12.6 kg) completed three separate weekly WBVT sessions. Baseline and post – WBVT intervention measurements of Q and H concentric torque were recorded, using an isokinetic dynamometer, at each session. Isokinetic knee extension and flexion was performed at 180os−1 through 90o range of motion. For the training intervention, vibration amplitude remained at 2 mm, while frequency was set at 0Hz, 30Hz or 50 Hz; randomised so participants experienced one frequency per session. Torque data (Nm) and H and Q ratio (H: Q) were analysed using 3-way and 2-way ANOVA with repeated measures respectively, with three within subjects’ factors: frequency, muscle group and intervention.Results: Main interaction effect (frequency x muscle group x intervention) was insignificant (P = 0.327). Significant muscle group x frequency (P = 0.029) and muscle group x intervention (P = 0.001) interactions were found. Intervention, regardless of WBVT, significantly increased concentric torque of H (P = 0.003) and significantly reduced concentric torque of Q (P = 0.031). While H: Q x frequency interaction was insignificant (P = 0.262), the intervention significantly improved H: Q (P = 0.001).Conclusions: Team sport athletes experience a muscle-specific response in peak concentric torque to lower-body exercise. Acute WBVT does not provide additional positive or negative effects on Q or H strength.

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Doyle, J. A., W. M. Sherman, and R. L. Strauss. "Effects of eccentric and concentric exercise on muscle glycogen replenishment." Journal of Applied Physiology 74, no. 4 (April 1, 1993): 1848–55. http://dx.doi.org/10.1152/jappl.1993.74.4.1848.

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Eccentric contractions appear to reduce muscle glycogen replenishment during the 1- to 10-day period after exercise. The main purpose of this study was to determine whether consuming a large amount of carbohydrate (1.6 g.kg-1.h-1) during the 4 h after glycogen-reducing exercise would produce different patterns of glycogen replenishment in human muscle that had undergone either eccentric or concentric contractions approximately 2 or 48 h earlier. Subjects cycled for 75 min and undertook interval exercise to deplete glycogen on days 1 and 3. After cycling exercise on day 1 only, subjects performed 10 sets of 10 repetitions of either concentric or eccentric contractions in opposite legs. During the 4 h after exercise, subjects consumed 0.4 g carbohydrate/kg body wt every 15 min. Biopsies were obtained immediately before the feedings and 4 h later, and blood was sampled every 15 min. For days 1 and 3 combined, total integrated areas for the glucose and insulin response curves averaged 1,683 mumol.ml-1.240 min-1 and 21,450 microU.ml-1.240 min-1, respectively. For days 1 and 3 combined, muscle glycogen replenishment after concentric exercise averaged 10 mmol.kg-1.h-1. On day 1 glycogen replenishment was similar for subjects performing either concentric or eccentric contractions. On day 3, however, glycogen replenishment was 25% lower (P < 0.05) in muscle that had undertaken eccentric contractions 48 h earlier than in concentrically exercised muscle. In conclusion, glycogen replenishment can be stimulated to a high rate when a large amount of carbohydrate is consumed after glycogen-depleting concentric exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

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Chen, Kesong, Yafei Li, and Jiajia Shi. "Optimization of Sparse Concentric Ring Arrays for Low Sidelobe." International Journal of Antennas and Propagation 2019 (June 2, 2019): 1–8. http://dx.doi.org/10.1155/2019/1485075.

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To lower the peak sidelobe level (PSLL) of sparse concentric ring arrays, a method with multiple design constraints that embed a function model into modified real genetic algorithm (MGA) and select the grid ring radii as optimization individual to synthesize sparse concentric ring arrays is proposed. The multiple constraints include the array aperture, the minimum element spacing, and the number of elements. The proposed method dynamically calculates the ratio of element on each ring, and it has a faster convergence rate than other algorithms. The MGA uses real number to code the optimization variable, and it reduces the complexity of coding and improves the search efficiency. Finally, the results demonstrate the accuracy and effectiveness of the algorithm.

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Ramin, Keyvan, and Mahmoud R. Maheri. "The Seismic Investigation of Off-Diagonal Steel Braced RC Frames." Slovak Journal of Civil Engineering 26, no. 3 (September 1, 2018): 49–64. http://dx.doi.org/10.2478/sjce-2018-0020.

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Abstract Steel bracing may be used to enhance the seismic strength of RC frames. Concentric steel bracing generally reduces ductility, which is a key component of seismic design. To overcome the problem, ductile steel brace-RC frame systems are therefore usually introduced in the form of eccentric braces. In the present study, the Off-Diagonal Bracing System (ODBS), which works as a concentric type of bracing, is investigated. In this paper the response of ODBS elements to cyclic loading is first explored and compared with those of other types of bracing such as X-bracing and inverted-V bracing systems. The time history analysis responses and cyclic hysteresis responses of a number of lowrise to mid-rise RC frames retrofitted with different types of bracing systems are then evaluated and compared. It is shown that under seismic excitation, a much reduced base shear is experienced by frames retrofitted with ODBS compared to other bracing systems. The results of time history and cyclic hysteresis response analyses also indicate a far greater energy dissipation capacity and ductility for the ODBS compared to other bracing systems. It is also concluded that ODBS performs best in lowrise frames. The out-of-plane buckling response of the ODBS is also investigated, and it is shown that a double-plated central connection can control such an adverse response.

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Bliss, Donald B., David Raudales, and Linda P. Franzoni. "A study of multi-element/multi-path concentric shell structures to reduce noise and vibration." Journal of the Acoustical Society of America 135, no. 4 (April 2014): 2386. http://dx.doi.org/10.1121/1.4877888.

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Moreno-Azze, Alejandro, José Luis Arjol-Serrano, David Falcón-Miguel, Chris Bishop, and Oliver Gonzalo-Skok. "Comparison of Three Eccentric Overload Training Strategies on Power Output and Interlimb Asymmetry in Youth Soccer Players." International Journal of Environmental Research and Public Health 18, no. 16 (August 4, 2021): 8270. http://dx.doi.org/10.3390/ijerph18168270.

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Background: The present study compared the effects of performing the lateral squat exercise in three different formats from eccentric overload training on concentric/eccentric peak/mean power and inter-limb asymmetries in young soccer players. Methods: Forty-five young male (U-17) soccer players were distributed into three groups. Two groups performed the same training volume with both legs, beginning with the weaker leg (SVW, n = 15) or with the stronger leg (SVS, n = 15). The third group executed double volume with the weaker leg and also commenced with such leg (DVW, n = 15) in the lateral squat during a 10-week period. Pre- and post-intervention metrics included concentric and eccentric peak/mean power during the lateral squat test and their corresponding asymmetries. Results: All groups improved all power variables. Concentric mean and peak power asymmetry were substantially reduced in the SVW (ES: 0.89), DVW (ES: 0.43), and in SVW (ES: 1.60). Eccentric mean and peak power asymmetry were also substantially decreased in SVW (ES: 0.81) and in DVW (ES: 0.68). Between-group analyses showed substantially better performance in concentric and eccentric variables with stronger and weaker legs in SVW and DVW groups compared with SVS. Conclusions: Those groups which started with the weaker leg showed greater both power enhancements and reductions on inter-limb asymmetries.

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Babault, Nicolas, Wacef Bazine, Gaëlle Deley, Christos Paizis, and Grégory Lattier. "Direct Relation of Acute Effects of Static Stretching on Isokinetic Torque Production With Initial Flexibility Level." International Journal of Sports Physiology and Performance 10, no. 1 (January 2015): 117–19. http://dx.doi.org/10.1123/ijspp.2013-0555.

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

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De Ruiter, C. J., and A. De Haan. "Similar effects of cooling and fatigue on eccentric and concentric force-velocity relationships in human muscle." Journal of Applied Physiology 90, no. 6 (June 1, 2001): 2109–16. http://dx.doi.org/10.1152/jappl.2001.90.6.2109.

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The purpose of this study was to investigate the effects of muscle temperature and fatigue during stretch (eccentric) and shortening (concentric) contractions of the maximally electrically activated human adductor pollicis muscle. After immersion of the lower arm in water baths of four different temperatures, the calculated muscle temperatures were 36.8, 31.6, 26.6, and 22.3°C. Normalized (isometric force = 100%) eccentric force increased with stretch velocity to maximal values of 136.4 ± 1.6 and 162.1 ± 2.0% at 36.8 and 22.3°C, respectively. After repetitive ischemic concentric contractions, fatigue was less at the lower temperatures, and at all temperatures the loss of eccentric force was smaller than the loss of isometric and concentric force. Consequently, normalized eccentric forces increased during fatigue to 159.7 ± 4.6 and 185.7 ± 7.3% at 36.8 and 22.3°C, respectively. Maximal normalized eccentric force increased exponentially ( r 2 = 0.95) when V max was reduced by cooling and/or fatiguing contractions. This may indicate that a reduction in cross-bridge cycling rate could underlie the significant increases in normalized eccentric force found with cooling and fatigue.

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Milandri, Giovanni, and Sudesh Sivarasu. "A Randomized Controlled Trial of Eccentric Versus Concentric Cycling for Anterior Cruciate Ligament Reconstruction Rehabilitation." American Journal of Sports Medicine 49, no. 3 (February 8, 2021): 626–36. http://dx.doi.org/10.1177/0363546520987566.

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Background: Persistent strength and biomechanical deviations remain after anterior cruciate ligament reconstruction (ACLR). Eccentric training may reduce these and associated reinjury or osteoarthritis risks. Hypothesis: For male patients who have undergone ACLR, eccentric training is more effective than concentric training at improving knee flexion angle and other biomechanical deviations, as well as strength and patient-reported outcomes, using a matched perceived exertion dose. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 26 men, 10-16 weeks after hamstring tendon graft ACLR, were randomized to an eccentric training group or a concentric control group. Both groups trained 3 times a week for 8 weeks using the same isokinetic cycle ergometer in a matched studio environment. Exercise dose was matched in training frequency, time, progression, and intensity using a target rating of perceived exertion. Baseline and follow-up testing included questionnaires, dynamometer strength testing, and walk/run gait analysis. Results: Eccentric training increased knee (+2.1°; P = .022) and hip (+2.1°; P = .010) flexion angles more than concentric training but not more than the minimal clinically important difference of 3°. Very large asymmetries in baseline knee abduction moment (walk, −0.10 N·m/kg/m; run, −0.54 N·m/kg/m) had not changed in either group by follow-up. Knee valgus angle effects were mixed. Tibial rotation angle increased in both groups, but concentric training was more effective at promoting symmetry ( P < .001). Both groups had similar increases in affected limb quadriceps strength and knee flexion moments during walk/run gait (by 20% to 33%). Hamstring strength increased in the eccentric group (+15.4%) but not the concentric group. Eccentric group limb forces were 33% to 70% higher than those of the concentric group, with a lower heart rate. Both groups had low pain scores throughout. Conclusion: For rehabilitation after ACLR, progressive eccentric cycle training was not more clinically effective than concentric training at a matched perceived intensity dose in male patients. This can guide exercise prescription for reducing gait and strength deviations of these patients. Registration: PACTR201602001449365 (Pan African Clinical Trials Registry), NHREC 4344 (South African).

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Sah, S., M. R. Tripathy, and A. Mittal. "Multiband and Miniaturized dual layer Antenna incorporated with FSS and DGS." Advanced Electromagnetics 7, no. 1 (January 29, 2018): 1–6. http://dx.doi.org/10.7716/aem.v7i1.534.

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A novel dual layer rectangular printed Antenna based on loop type Frequency selective surfaces with five concentric rings and I shaped defected ground structure (DGS) is designed and investigated. The deigned antenna is tested for application in C band, WiFi devices and some cordless telephones and X band radiolocation, airborne and naval radars as multiband operational frequencies are at 5.5GHz, 6.81GHz, 9.3GHz and thus covers two wireless communication band C Band (4 to 8GHz ) and X band (8 to 12 GHz) The bandwidth is 200MHz, 300MHz and 1GHz respectively and measured gain of this designed antenna are 2.42dBi against 5.5GHz, 2.80dBi against 6.81GHz, 6.76dBi against 9.3GHz. The proposed antenna in addition to multiband operation also exhibits minituarization.The Floquet port technique is used to analyse concentric rings. The Results comparison of proposed structure with the basic dual layer antenna resonaing at 5.5GHz shows the patch area is reduced by 58.15% while the volume of the antenna is reduced by 81.5%.

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Hollman, David S., Henry F. Schaefer, and Edward F. Valeev. "Semi-exact concentric atomic density fitting: Reduced cost and increased accuracy compared to standard density fitting." Journal of Chemical Physics 140, no. 6 (February 14, 2014): 064109. http://dx.doi.org/10.1063/1.4864755.

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Dib, Nihad. "Design of planar concentric circular antenna arrays with reduced side lobe level using symbiotic organisms search." Neural Computing and Applications 30, no. 12 (April 18, 2017): 3859–68. http://dx.doi.org/10.1007/s00521-017-2971-2.

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Alekseev, Viktor. "Deep structure and geodynamic conditions of granitoid magmatism in the Eastern Russia." Journal of Mining Institute 243 (June 14, 2020): 259. http://dx.doi.org/10.31897/pmi.2020.3.259.

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We investigated the deep structure of the lithosphere and the geodynamic conditions of granitoid magmatism in the Eastern Russia within the borders of the Far Eastern Federal District. The relevance of the work is determined by the need to establish the geotectonic and geodynamic conditions of the granitoids petrogenesis and ore genesis in the Russian sector of the Pacific Ore Belt. The purpose of the article is to study the deep structure of the lithosphere and determine the geodynamic conditions of granitoid magmatism in the East of Russia. The author's data on the magmatism of ore regions, regional granitoids correlations, archive and published State Geological Map data, survey mapping, deep seismic sounding of the earth's crust, gravimetric survey, geothermal exploration, and other geophysical data obtained along geotraverses. The magma-controlling concentric geostructures of the region are distinguished and their deep structure is studied. The connection of plume magmatism with deep structures is traced. The chain of concentric geostructures of Eastern Russia controls the trans-regional zone of leucocratization of the earth's crust with a width of more than 1000 km, which includes the Far Eastern zone of Li-F granites. Magmacontrolling concentric geostructures are concentrated in three granitoid provinces: Novosibirsk-Chukotka, Yano-Kolyma, and Sikhote-Alin. The driving force of geodynamic processes and granitoid magmatism was mantle heat fluxes in the reduced zones of the lithospheric slab. The distribution of slab windows along the Pacific mobile belt's strike determines the location of concentric geostructures and the magnitude of granitoid magmatism in the regional provinces. Mantle diapirs are the cores of granitoid ore-magmatic systems. The location of the most important ore regions of the Eastern Russia in concentric geostructures surrounded by annuli of negative gravity anomalies is the most important regional metallogenic pattern reflecting the correlation between ore content and deep structure of the earth's crust.

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WENG, HUEI CHU, CHA'O-KUANG CHEN, and MIN-HSING CHANG. "Stability of micropolar fluid flow between concentric rotating cylinders." Journal of Fluid Mechanics 631 (July 17, 2009): 343–62. http://dx.doi.org/10.1017/s0022112009007150.

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In this study, the theory of micropolar fluids is employed to study the stability problem of flow between two concentric rotating cylinders. The field equations subject to no-slip conditions (non-zero velocity and microrotation velocity components) at the wall surfaces are solved. The analytical solutions of the velocity and microrotation velocity fields as well as the shear stress difference, couple stress and strain rate for basic flow are obtained. The equations with respect to non-axisymmetric disturbances are derived and solved by a direct numerical procedure. It is found that non-zero wall-surface microrotation velocity makes the flow faster and more unstable. Moreover, it tends to reduce the limits of critical non-axisymmetric disturbances. The effect on the stability characteristics can be magnified by increasing the microstructure or couple-stress parameter or the microinertia parameter for the cases of corotating cylinders and a stationary outer cylinder or by decreasing the radius ratio or the microinertia parameter for the case of counterrotating cylinders.

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Lundberg, Tommy R., Rodrigo Fernandez-Gonzalo, and Per A. Tesch. "Exercise-induced AMPK activation does not interfere with muscle hypertrophy in response to resistance training in men." Journal of Applied Physiology 116, no. 6 (March 15, 2014): 611–20. http://dx.doi.org/10.1152/japplphysiol.01082.2013.

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As aerobic exercise (AE) may interfere with adaptations to resistance exercise (RE), this study explored acute and chronic responses to consecutive AE (∼45 min cycling) and RE (4 × 7 maximal knee extensions) vs. RE only. Ten men performed acute unilateral AE + RE interspersed by 15 min recovery. The contralateral leg was subjected to RE. This exercise paradigm was then implemented in a 5-wk training program. Protein phosphorylation, gene expression, and glycogen content were assessed in biopsies obtained from the vastus lateralis muscle of both legs immediately before and 3 h after acute RE. Quadriceps muscle size and in vivo torque were measured, and muscle samples were analyzed for citrate synthase activity and glycogen concentration, before and after training. Acute AE reduced glycogen content (32%; P < 0.05) and increased ( P < 0.05) phosphorylation of AMPK (1.5-fold) and rpS6 (1.3-fold). Phosphorylation of p70S6K and 4E-BP1 remained unchanged. Myostatin gene expression was downregulated after acute AE + RE but not RE. Muscle size showed greater ( P < 0.05) increase after AE + RE (6%) than RE (3%) training. Citrate synthase activity (18%) and endurance performance (22%) increased ( P < 0.05) after AE + RE but not RE. While training increased ( P < 0.05) in vivo muscle strength in both legs, normalized and concentric torque increased after RE only. Thus AE activates AMPK, reduces glycogen stores, and impairs the progression of concentric force, yet muscle hypertrophic responses to chronic RE training appear not to be compromised.

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Journal articles on the topic 'Concentric Reducer'

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