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1
Choi, Hyun-Min, Chansol Hurr und Sukwon Kim. „Effects of Elastic Band Exercise on Functional Fitness and Blood Pressure Response in the Healthy Elderly“. International Journal of Environmental Research and Public Health 17, Nr. 19 (29.09.2020): 7144. http://dx.doi.org/10.3390/ijerph17197144.
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Purpose: This study investigated the effects of 12 weeks of moderate intensity elastic band exercise (EBE) on functional fitness and blood pressure parameters in the elderly. Methods: 27 healthy older adults were randomly assigned to an exercise group (n = 15, age: 75.1 ± 1.4 years) and a control group (n = 12, age: 72.3 ± 1.4 years). Participants performed EBE for 60 min, three times a week, over the course of three months. The EBE consisted of incremental resistance and aerobic exercises designed to improve whole body fitness. Functional fitness and resting cardiovascular parameters were assessed before and after the exercise training program. Results: Grip strength, sit and reach, and one-leg stance improved significantly in the exercise group, while no significant improvements were found in chair stand and timed up and go (p < 0.05). Cardiovascular parameters including systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure significantly decreased in the exercise group relative to the control group (p < 0.05). Conclusions: Findings of the present study suggest that safe, inexpensive, and easily accessible EBE program with circuit training components play a significant role in improving upper and lower body fitness, as well as cardiovascular fitness, in the elderly.
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Hsu, Yen-I., Ying-Chou Chen, Chia-Lun Lee und Nai-Jen Chang. „Effects of Diet Control and Telemedicine-Based Resistance Exercise Intervention on Patients with Obesity and Knee Osteoarthritis: A Randomized Control Trial“. International Journal of Environmental Research and Public Health 18, Nr. 15 (21.07.2021): 7744. http://dx.doi.org/10.3390/ijerph18157744.
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This study investigated the effects of home-based nutritional and telemedicine-based resistance exercise interventions on improving body composition, blood biochemistry, and lower-limb functional performance. In total, 66 obese patients with mild-to-moderate knee osteoarthritis were randomly divided into a diet control group (D), elastic band resistance exercise group (E), and diet control plus elastic band exercise group (D + E). Each group was supervised by a clinical dietitian and follow-up was conducted via telephone calls or a communication application to track the participants’ progress. After 12 weeks of intervention, the D (p < 0.001) and D + E (p < 0.001) groups achieved significant weight loss. The D + E group exhibited a significant reduction in body fat relative to the D (p = 0.019) and E (p = 0.012) groups. Compared with the D (p = 0.002) and E (p = 0.019) groups, the D + E group achieved significant improvements in the timed up-and-go test and Western Ontario and McMaster Universities Osteoarthritis total scale. The D + E group experienced significant improvements in total cholesterol (p = 0.001), low-density lipoprotein cholesterol (p = 0.01), and triglyceride levels (p = 0.007) relative to other groups. In conclusion, individual diet control intervention combined with telemedicine-based resistance exercise intervention significantly improved the body composition, blood biochemistry, and lower-limb functional performance of the investigated population with comorbid conditions.
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Liu, Sheng, Fengji Dai, Shaobo Zhang, Yangqing Wang und Zhenhua Wang. „Trend-aware motion planning for wheeled mobile robots operating in dynamic environments“. International Journal of Advanced Robotic Systems 17, Nr. 4 (01.07.2020): 172988142092529. http://dx.doi.org/10.1177/1729881420925292.
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Planning collision-free trajectories is essential for wheeled mobile robots operating in dynamic environments safely and efficiently. Most current trajectory generation methods focus on achieving optimal trajectories in static maps and considering dynamic obstacles as static depending on the precise motion estimation of the obstacles. However, in realistic applications, dealing with dynamic obstacles that have low reliable motion estimation is a common situation. Furthermore, inaccurate motion estimation leads to poor quality of motion prediction. To generate safe and smooth trajectories in such a dynamic environment, we propose a motion planning algorithm called trend-aware motion planning (TAMP) for dynamic obstacle avoidance, which combines with timed-elastic band. Instead of considering dynamic obstacles as static, our planning approach predicts the moving trends of the obstacles based on the given estimation. Subsequently, the approach generates a trajectory away from dynamic obstacles, meanwhile, avoiding the moving trends of the obstacles. To cope with multiple constraints, an optimization approach is adopted to refine the generated trajectory and minimize the cost. A comparison of our approach against other state-of-the-art methods is conducted. Results show that trajectories generated by TAMP are robust to handle the poor quality of obstacles’ motion prediction and have better efficiency and performance.
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Chen, Shu-Mei, Feng-Chih Shen, Jung-Fu Chen, Wen-Dien Chang und Nai-Jen Chang. „Effects of Resistance Exercise on Glycated Hemoglobin and Functional Performance in Older Patients with Comorbid Diabetes Mellitus and Knee Osteoarthritis: A Randomized Trial“. International Journal of Environmental Research and Public Health 17, Nr. 1 (27.12.2019): 224. http://dx.doi.org/10.3390/ijerph17010224.
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Type 2 diabetes mellitus (T2DM) is significantly associated with osteoarthritis (OA). This study investigated the effects of two resistance exercise approaches on glycated hemoglobin (HbA1c) level and function performance. Enrolled were 70 older patients with both T2DM and knee OA. The dynamic group performed resistance exercises with an elastic resistance band. The isometric group underwent isometric contraction exercises. After the 12-week intervention, a significant within-group improvement (all p < 0.001) was observed for the chair stand test (CST; 10.8%, vs. 7.1%), timed up and go (TUG) test (12.6% vs. 7.6%), Western Ontario and McMaster Universities Osteoarthritis (WOMAC) physical function subscale (62.3% vs. 36.1%), and overall WOMAC (54.5% vs. 34.5%) in the dynamic and isometric group, respectively. In addition, in terms of between-group differences, the dynamic group had significant improvements in CST (p = 0.011), TUG (p < 0.001), WOMAC physical function subscale (p = 0.033), and overall WOMAC (p = 0.036) scores compared with the isometric group. However, no significant change in HbA1c was observed in either group. In conclusion, the dynamic resistance exercise significantly improved muscle strength, dynamic balance, and physical function in this comorbid population; however, there was no notable difference in change in HbA1c among different resistance exercises.
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Zhang, Wentao, Guodong Zhai, Zhongwen Yue, Tao Pan und Ran Cheng. „Research on Visual Positioning of a Roadheader and Construction of an Environment Map“. Applied Sciences 11, Nr. 11 (28.05.2021): 4968. http://dx.doi.org/10.3390/app11114968.
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The autonomous positioning of tunneling equipment is the key to intellectualization and robotization of a tunneling face. In this paper, a method based on simultaneous localization and mapping (SLAM) to estimate the body pose of a roadheader and build a navigation map of a roadway is presented. In terms of pose estimation, an RGB-D camera is used to collect images, and a pose calculation model of a roadheader is established based on random sample consensus (RANSAC) and iterative closest point (ICP); constructing a pose graph optimization model with closed-loop constraints. An iterative equation based on Levenberg–Marquadt is derived, which can achieve the optimal estimation of the body pose. In terms of mapping, LiDAR is used to experimentally construct the grid map based on open-source algorithms, such as Gmapping, Cartographer, Karto, and Hector. A point cloud map, octree map, and compound map are experimentally constructed based on the open-source library RTAB-MAP. By setting parameters, such as the expansion radius of an obstacle and the updating frequency of the map, a cost map for the navigation of a roadheader is established. Combined with algorithms, such as Dijskra and timed-elastic-band, simulation experiments show that the combination of octree map and cost map can support global path planning and local obstacle avoidance.
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Malanon, Sasatorn, Surachai Dechkunakorn, Niwat Anuwongnukroh und Wassana Wichai. „Comparison of Three Commercial Latex and Non-Latex Orthodontic Elastic Bands“. Key Engineering Materials 814 (Juli 2019): 354–59. http://dx.doi.org/10.4028/www.scientific.net/kem.814.354.
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Orthodontic elastic bands are commonly made from natural rubber because they provide high resiliency at a reasonable cost. However, hypersensitivity related to protein present in latex have been reported in some patients which has led to increased usage of non-latex elastic alternatives. Therefore, the assessment of their mechanical properties is of importance. The objective of this study was to compare the physical and mechanical properties of three commercial latex and non-latex type orthodontic elastic bands. Samples of latex and non-latex type orthodontic elastics from manufacturers – AO (6.5oz), MASEL (6.0oz), GAC (6.0oz), with 3/16-inch diameter were selected. Firstly, the physical characteristics (width, cross-sectional thickness, and inner diameter) of the elastic bands were determined, following which their mechanical properties [initial extension force (F0), 24 h-residual force (F24), percentage of force decay, force exerted at 3 times the inner diameter (F3xID) and breaking force] were tested. The data were analyzed with Mann-Whitney U test and multiple comparisons among the groups were done with Kruskal-Wallis Test (p< 0.05). Significant differences were found in the physical characteristics and mechanical properties among each brand and type of elastics. AO elastic bands had significantly low F0 and F24 compared with the others. While the percentage of force decay at 24 h was greatest in AO followed by MASEL and GAC. Non-latex type elastics showed greater force decay than latex type ones, approximately 30-40% and 20-30% of the initial force in non-latex and latex type elastic, respectively. AO elastics showed the highest F3xID and also the lowest breaking force. Overall, non-latex type elastics exhibited lower breaking force compared to latex type ones. Wide variations were observed in the physical and mechanical characteristics among same manufacturer and same elastic type. All commercial brands presented higher F3xID than that stated by the manufacturers. Non-latex type elastics showed greater force decay over 24 h than latex type ones. The differences in the properties between the 2 types of the elastics could be due to the differences in their structure and polymers composition.
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Sambataro, Sergio, Salvatore Bocchieri, Luigi Bafumi, Luca Fiorillo, Gabriele Cervino und Marco Cicciù. „Elastics Selector Gauge as Orthodontics Device Applied to Inter-Maxillary Traction during Malocclusion Correction“. Journal of Functional Morphology and Kinesiology 4, Nr. 3 (26.08.2019): 63. http://dx.doi.org/10.3390/jfmk4030063.
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Elastics are the simplest device that can be used during a class correction in orthodontics, and despite the simplicity of a latex band, they are very effective and powerful. The resultant inter-maxillary force affects not only the teeth, but even the mandibular position, and consequently the temporomandibular joints (TMJ). The purpose of our work is to simplify the use of elastics, and to reduce the amount of inventory for orthodontists, because there is a lot of merceology available on the market, and different ways of using the elastics. The use of elastics in clinical practice is based on the force extension values, which are given by the manufacturer for the different sizes of the elastics, generally when they are stretched to three times their lumen size. Various configurations allow for the correction of different malocclusions. We propose a new classification and a new device, the elastic selector gauge, in order to allow clinicians to quickly and easily choose the right elastic in all conditions.
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Notaroberto, Daniela Ferreira de Carvalho, Mariana Martins e. Martins, Maria Teresa de Andrade Goldner, Alvaro de Moraes Mendes und Cátia Cardoso Abdo Quintão. „Force decay evaluation of latex and non-latex orthodontic intraoral elastics: in vivo study“. Dental Press Journal of Orthodontics 23, Nr. 6 (Dezember 2018): 42–47. http://dx.doi.org/10.1590/2177-6709.23.6.042-047.oar.
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ABSTRACT Objective: This clinical study was conducted in order to evaluate force decay over time of latex and non-latex orthodontic intraoral elastics. Methods: Patients (n = 15) were evaluated using latex and non-latex elastics in the periods of : 0, 1, 3, 12 and 24 hours. The rubber bands were transferred to the testing machine (EMIC DL-500 MF), and force values were recorded after stretching the elastic to a length of 25mm. Paired t test was applied and analysis of variance (ANOVA) was used to evaluate the variation of force generated. LSD (Fisher’s least significant difference) post-hoc test was thus employed. Results: As regards the initial forces (zero time), the values of force for non-latex elastic were slightly higher than for the latex elastic. In the subsequent times, the forces generated by the latex elastic showed higher values. Regarding the material degradation, at the end of 24 hours the highest percentage was observed for non-latex elastic. Conclusions: The latex elastics had a more stable behavior during the studied period, compared with non-latex.
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Notaroberto, Daniela Ferreira de Carvalho, Mariana Martins e. Martins, Maria Teresa de Andrade Goldner, Cátia Abdo Quintão und Alvaro de Moraes Mendes. „Analysis in vitro of strength degradation comparing latex and non-latex elastics“. Brazilian Journal of Oral Sciences 17 (30.10.2018): e18144. http://dx.doi.org/10.20396/bjos.v17i0.8653813.
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Aim: This study was conducted in order to evaluate and compare the behavior of latex and non-latex elastics, as the loss of strength over time in vitro. Methods: The study evaluated 15 of each elastic material for the pre-selected times: 0, 1, 3, 12 and 24 hours. The rubber bands were transferred to the testing machine (EMIC DL-500 MF). The force values were recorded after stretching the elastic to a length of 25mm. Independent t-test was applied. Analysis of variance (ANOVA) was used to check the variation of the forces generated between those determined times. To identify between which times the difference was present, Tukey post-hoc test was accomplished. Results: As regards the initial forces (zero time), the values of force for non-latex elastic were slightly higher than the latex elastic. In subsequent times, the forces generated by the latex elastic showed higher values. Regarding the material degradation, at the end of 24 hours the highest percentage was observed for non-latex elastic. Conclusion: The latex elastic had a more stable behavior during the studied period compared with non-latex.
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Magyar, Bence, Nikolaos Tsiogkas, Jeremie Deray, Sammy Pfeiffer und David Lane. „Timed-Elastic Bands for Manipulation Motion Planning“. IEEE Robotics and Automation Letters 4, Nr. 4 (Oktober 2019): 3513–20. http://dx.doi.org/10.1109/lra.2019.2927956.
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Wu, Weibing, Xiaodan Liu, Peijun Li, Ning Li und Zhenwei Wang. „Effect of Liuzijue Exercise Combined with Elastic Band Resistance Exercise on Patients with COPD: A Randomized Controlled Trial“. Evidence-Based Complementary and Alternative Medicine 2018 (11.06.2018): 1–12. http://dx.doi.org/10.1155/2018/2361962.
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Objectives. This study aimed to investigate the effect of Liuzijue exercise combined with elastic band resistance exercise on patients with chronic obstructive pulmonary disease (COPD) to provide a convenient, safe, and cost-effective exercise. Methods. Subjects were randomly divided into the control group (CG), the Liuzijue exercise group (LG), and the Liuzijue exercise combined with elastic band resistance exercise group (LEG), with 20 patients in each group. The LG performed Liuzijue exercise six times a week (two exercise sessions in the hospital and four exercise sessions at home). The LEG includes Liuzijue exercise similar to the LG and elastic band resistance exercise three times a week, with elastic band exercise implemented after Liuzijue exercise. Spirometry, 6-minute walking test (6MWT), 30-second sit-to-stand test (30 s SST), handgrip strength test, and St. George’s Respiratory Questionnaire (SGRQ) were performed at baseline and at the end of intervention. Results. After six-month intervention, the forced expiratory volume in 1 second (% predicted), 6-minute walking distance (6MWD), 6MWD%pred, 30 s SST, and SGRQ were significantly improved in the intervention groups (p < 0.01) and handgrip strength was increased significantly in the LG and LEG (p = 0.03 and p = 0.001, respectively). Furthermore, improvements in 6MWD and SGRQ were distinguished in the intervention groups compared with the CG (p < 0.01). No difference was significant in all of the outcomes between the LG and the LEG. Conclusions. The intervention program of Liuzijue exercise combined with elastic band resistance exercise and Liuzijue exercise only has beneficial effects on COPD patients especially in the aspect of exercise capacity and quality of life.
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Liu, Hongxing, und Jiu Hui Wu. „Viscoelastic multi-resonator mechanism for broadening low-frequency band-gap of acoustic metamaterials“. European Physical Journal Applied Physics 86, Nr. 1 (April 2019): 10901. http://dx.doi.org/10.1051/epjap/2019180361.
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In this paper, viscoelastic multi-resonator mechanism for broadening low-frequency band-gaps of acoustic metamaterials is investigated. Firstly, the metamaterial unit consists of dual-mass and dual-viscoelasticity is proposed which can generate multiple resonances to form multiple band-gaps, and further the broadened band-gaps are realized by modulating the effect of the viscoelasticity. Secondly, for the dual-viscoelasticity, the band-gaps and transmission spectrum under the cases of with the consistent and inconsistent viscoelasticity are calculated. Comparing with the consistent case, by adjusting the viscoelasticity in the inconsistent case, the storage modulus changes the fastest and obtains a smaller and a larger elastic modulus at the corresponding starting frequency and ending frequency of the band-gap, in which the band-gap can be broadened and shifted to the low frequency since the resonant frequency is determined by the elastic modulus, and for the loss modulus, it has little effects on the width of the band-gap, but has great influence on the transmission coefficient. Thirdly, by adjusting the inconsistent viscoelastic parameters based on the above rules, the band width is increased by 1.7 times (1.3 times for the absolute band width) than the consistent structure and the band-gap is shifted to the low frequency by 31% (about 345 Hz). The viscoelastic multi-resonator mechanism can be used to practical applications of viscoelastic metamaterials.
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Andersen, Vidar, Marius Fimland, Kristoffer Cumming, Øyvind Vraalsen und Atle Saeterbakken. „Explosive Resistance Training Using Elastic Bands in Young Female Team Handball Players“. Sports Medicine International Open 02, Nr. 06 (November 2018): E171—E178. http://dx.doi.org/10.1055/a-0755-7398.
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AbstractThe aim of the study was to examine the effects of full-body elastic resistance band training in young female team handball players. 12 players (16.5±0.7 years, 166±5.0 cm, 65.9±8.8 kg) completed an 11-week control period followed by a 9-week elastic resistance band training period. The training program, consisting of 6 exercises, was incorporated into the teams’ regular handball training sessions 3 times per week. Each exercise was performed with 3 sets of 6–10 explosive repetitions (5–9 on the Borg CR10 Scale®). The maximal power output in squat and bench press, jump height, throwing velocity and repeated agility run was tested before and after the control and training periods. The elastic resistance band period had greater improvement vs. the control period for countermovement jump with or without arm swing (10% vs. –6 to –2%) and power output at lighter loads (10 to 12% vs. –6 to 0%). For the 3 throwing velocity tests, there were tendencies towards increased velocity in the elastic resistance band period compared to the control period (p=0.07–0.10). For the repeated agility run, there was a reduction in the mean and fastest time compared to the training period (2 to 3% vs. –1 to 1%). In conclusion, a brief, elastic resistance band training program, incorporated into the regular handball training sessions, improved explosive lower-limb performance in young female handball players more than handball training alone.
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Yoo, Inhwa, und Hyung-Min Yoon. „The Effect of Two Exercise Types in the 8 Week Exercise Training on the Physical Fitness of Elderly Women“. Asian Journal of Kinesiology 22, Nr. 1 (31.01.2020): 15–23. http://dx.doi.org/10.15758/ajk.2020.22.1.15.
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OBJECTIVES The purpose of this study was to investigate the effect of two exercise types (Gyrokinesis exercise and Elastic band exercise) in the 8 week exercise training on the physical fitness of elderly women.METHODS The subjects of this study were 57 elderly women between 65 and 80 years old, who had no abnormality in the Physical Readiness Questionnaire (PAR-Q test) and were able to do physical activity on the orthopedic standpoints. The subjects were divided into three groups: Gyrokinesis Exercise Group (GKEG: n=19), Elastic Band Exercise Group (EBEG: n=20), and Control Group (CG: n=18). The subjects performed a Gyrokinesis Exercise in GKEG and an Elastic Band Exercise in EBEG for 50 minutes a day (10 minutes for warm-up, 30 minutes for main exercise, 10 minutes for cool-down), and 3 times a week for a total of 8 weeks. The subjects of CG did not participate in any particular exercise program but only everyday life. The dependent variables were Physical Fitness: Upper Muscular Endurance, 30-Second Arm Curl. Lower Flexibility, Dynamic Balance, Endurance. one-way ANOVA with repeated measurements was used to test the hypothesis in this study. A post hoc was conducted only when there was an interaction effect between groups and measurements. The difference of the post-test between groups were analyzed through Scheffe method after one-way ANOVA. The statistical significance level of this study was α=.05.RESULTS Gyrokinesis and Elastic Band Exercises were both effective on the physical fitness of elderly women: Upper Muscular Endurance, 30-Second Arm Curl, Lower Flexibility, Dynamic Balance, and Endurance. However, there were no differences in exercise effects after 8 week exercise training between the Gyrokinesis Exercise Group and the Elastic Band Exercise Group.CONCLUSIONS It is concluded that Gyrokinesis and Elastic Band exercise programs should be encouraged to improve physical fitness of elderly women and we need a follow-up study with longer term exercise training programs to find the differences in exercise effects between Gyrokinesis Exercise and Elastic Band Exercise.
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Shoepe, Todd, David Ramirez, Robert Rovetti, David Kohler und Hawley Almstedt. „The Effects of 24 weeks of Resistance Training with Simultaneous Elastic and Free Weight Loading on Muscular Performance of Novice Lifters“. Journal of Human Kinetics 29, Nr. 1 (01.09.2011): 93–106. http://dx.doi.org/10.2478/v10078-011-0043-8.
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The Effects of 24 weeks of Resistance Training with Simultaneous Elastic and Free Weight Loading on Muscular Performance of Novice LiftersThe purpose of this investigation was to assess the effectiveness of variable resistance as provided through elastic plus free weight techniques in college aged males and females. Twenty novice lifters were randomly assigned to a traditional free weight only (6 males and 5 females) or elastic band plus free weight group (5 males and 5 females) and 9 more normally active controls (5 males and 4 females), were recruited to maintain normal activity for the duration of the study. No differences existed between control, free weight and elastic band at baseline for age, body height, body mass, body mass index, and body fat percentage. One-repetition maximums were performed for squat and bench press while both strength and power were assessed using isokinetic dynamometry. Elastic groups and free-weight groups completed 24 weeks of whole body, periodized, high intensity resistance (65-95% of one-repetition maximum) training three times/week. Training programs were identical except that the elastic group trained the barbell squat, bench press and stiff-legged deadlift with 20-35% of their total prescribed training loads coming from band resistance (assessed at the top of the range of motion) with the remainder from free weight resistance. A mixed-model analysis revealed that peak torque, average power and one-repetition maximums for squat were significantly greater after training for the elastic group compared to the control (p<0.05). In addition, the free weight group also showed significantly greater improvements over the control in peak torque and one-repetition maximums for squat and bench press. No significant differences were observed between the elastic band and free weight groups. Combined variable elastic band plus free weight exercises are effective at increasing strength and power similar to free-weights alone in novice college aged males and females. However, due to complexity in set-up and load assignment elastic adoption by novice lifters in an unsupervised situation is not advised.
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Marteau, Pierre-Francois. „Times Series Averaging and Denoising from a Probabilistic Perspective on Time–Elastic Kernels“. International Journal of Applied Mathematics and Computer Science 29, Nr. 2 (01.06.2019): 375–92. http://dx.doi.org/10.2478/amcs-2019-0028.
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Abstract In the light of regularized dynamic time warping kernels, this paper re-considers the concept of a time elastic centroid for a set of time series. We derive a new algorithm based on a probabilistic interpretation of kernel alignment matrices. This algorithm expresses the averaging process in terms of stochastic alignment automata. It uses an iterative agglomerative heuristic method for averaging the aligned samples, while also averaging the times of their occurrence. By comparing classification accuracies for 45 heterogeneous time series data sets obtained by first nearest centroid/medoid classifiers, we show that (i) centroid-based approaches significantly outperform medoid-based ones, (ii) for the data sets considered, our algorithm, which combines averaging in the sample space and along the time axes, emerges as the most significantly robust model for time-elastic averaging with a promising noise reduction capability. We also demonstrate its benefit in an isolated gesture recognition experiment and its ability to significantly reduce the size of training instance sets. Finally, we highlight its denoising capability using demonstrative synthetic data. Specifically, we show that it is possible to retrieve, from few noisy instances, a signal whose components are scattered in a wide spectral band.
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Keller, Martin, Frank Hoffmann, Carsten Hass, Torsten Bertram und Alois Seewald. „Planning of Optimal Collision Avoidance Trajectories with Timed Elastic Bands“. IFAC Proceedings Volumes 47, Nr. 3 (2014): 9822–27. http://dx.doi.org/10.3182/20140824-6-za-1003.01143.
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Cebrecos, Alejandro, Dimitri Krattiger, Victor J. Sánchez-Morcillo, Vicent Romero-García und Mahmoud I. Hussein. „The finite-element time-domain method for elastic band-structure calculations“. Computer Physics Communications 238 (Mai 2019): 77–87. http://dx.doi.org/10.1016/j.cpc.2018.12.016.
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Liu, Zhihao, und Qinhe Gao. „In-plane vibration response of time and frequency domain with rigid-elastic coupled tire model with continuous sidewall“. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 232, Nr. 4 (05.12.2017): 429–45. http://dx.doi.org/10.1177/1464419317744681.
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The in-plane vibration characteristic of time and frequency domain for heavy-loaded radial tire with a larger flat ratio (close to 1) is researched by utilizing the rigid-elastic coupled tire model with continuous sidewall. The sidewall bending stiffness is considered and the flexible beam on the elastic continuous beam tire model is proposed and investigated analytically to simulate the in-plane vibration of the heavy-loaded radial tire within more wider frequency band. The rigid-elastic coupled tire model is derived with finite difference method and the analytical stiffness matrix; mass matrix is formed based on the geometrical and structural parameters of heavy-loaded radial tire. Structural parameters are identified utilizing genetic algorithm based on the error between the analytical and experimental modal frequency. In-plane frequency domain transfer function and time domain dynamics response of heavy-loaded radial tire is investigated and compared with the experimental result. Experimental and theoretical results show that in-plane rigid-elastic coupled tire model with sidewall bending stiffness can be used to precisely predict the transfer function and vibration feature within the frequency band of 300 Hz, compared with the tire model with the distributed independent sidewall element. The flexible beam on the elastic continuous beam tire model and rigid-elastic coupled tire model with continuous sidewall can be extended to the dynamic analysis of the tire with larger flat ratio or the tire under the impulsive loading conditions.
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LIN, DAN-JAE, TZU-NING HUNG, MING-TZU TSAI, JUI-TING HSU, HENG-LI HUANG und JIAN-HONG YU. „THE EFFECT OF CYCLIC STRETCHING SPEED ON THE FORCE DEGRADATION OF ORTHODONTIC ELASTIC BANDS“. Journal of Mechanics in Medicine and Biology 13, Nr. 01 (10.01.2013): 1350017. http://dx.doi.org/10.1142/s0219519413500176.
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This study evaluated the effect of the cyclic stretching speed on the force degradation of orthodontic elastics. Forty-five natural rubber bands (3M Unitek™) were stretched at different speeds in three groups: (1) static stretching test, (2) cyclic stretching test at a speed of 80 mm/min, and (3) cyclic stretching at a speed of 160 mm/min. A material tester and customized strain gauge were used to measure the residual force of the elastics in 37°C artificial saliva at different times. One-way repeated-measure analysis of variance followed by Scheffe's post-hoc comparison and t-test were used for statistical analysis. In Group 1, the force of the elastics degraded with time, with two separate phases being observed — distinctive degradation after 15 min and stabilization after 120 min. The cyclic stretching in Group 2 produced a significant deviation in the residual force and the initial force from the first minute, and stabilization after 300 min. After 1,440 min, 60% of the bands had snapped. Under accelerated stretching, no areas of relative stability were observed between the start of stretching to the start of breaking. After 1,440 high-speed stretches, 87% of the elastics in Group 3 snapped. These results indicate that the stretching speed affects the stability of the residual force of elastics. Cyclic stretching at high speed immediately induces a rapid degradation of the elastic's force and increases its probability of breakage.
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Nakano, Aiichiro. „A space–time-ensemble parallel nudged elastic band algorithm for molecular kinetics simulation“. Computer Physics Communications 178, Nr. 4 (Februar 2008): 280–89. http://dx.doi.org/10.1016/j.cpc.2007.09.011.
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Yang, Jidong, Hejun Zhu, George McMechan, Houzhu Zhang und Yang Zhao. „Elastic least-squares reverse time migration in vertical transverse isotropic media“. GEOPHYSICS 84, Nr. 6 (01.11.2019): S539—S553. http://dx.doi.org/10.1190/geo2018-0887.1.
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Using adjoint-based elastic reverse time migration, it is difficult to produce high-quality reflectivity images due to the limited acquisition apertures, band-limited source time function, and irregular subsurface illumination. Through iteratively computing the Hessian inverse, least-squares migration enables us to reduce the point-spread-function effects and improve the image resolution and amplitude fidelity. By incorporating anisotropy in the 2D elastic wave equation, we have developed an elastic least-squares reverse time migration (LSRTM) method for multicomponent data from the vertically transversely isotropic (VTI) media. Using the perturbed stiffness parameters [Formula: see text] and [Formula: see text] as PP and PS reflectivities, we linearize the elastic VTI wave equation and obtain a Born modeling (demigration) operator. Then, we use the Lagrange multiplier method to derive the corresponding adjoint wave equation and reflectivity kernels. With linearized forward modeling and adjoint migration operators, we solve a linear inverse problem to estimate the subsurface reflectivity models for [Formula: see text] and [Formula: see text]. To reduce the artifacts caused by data over-fitting, we introduce total-variation regularization into the reflectivity inversion, which promotes a sparse solution in terms of the model derivatives. To accelerate the convergence of LSRTM, we use source illumination to approximate the diagonal Hessian and use it as a preconditioner for the misfit gradient. Numerical examples help us determine that our elastic VTI LSRTM method can improve the spatial resolution and amplitude fidelity in comparison to adjoint migration.
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Sakane, Masao, Masateru Ohnami, Teruyoshi Awaya und Nakao Shirafuji. „Frequency and Hold-Time Effects on Low Cycle Fatigue Life of Notched Specimens at Elevated Temperature“. Journal of Engineering Materials and Technology 111, Nr. 1 (01.01.1989): 54–60. http://dx.doi.org/10.1115/1.3226433.
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This paper describes the frequency and hold-time effects on high temperature low cycle fatigue for round notched specimens. Unnotched and notched specimens having different elastic stress concentration factors were fatigued under triangular and trapezoidal stress waves at frequencies ranging from 5 Hz to 0.0001 Hz at 873 K. The three specific fracture characteristics were observed: cycle dependent, time dependent, and cycle-time dependent. The respective notch sensitivity occurred in the respective fracture regime. The fatigue life of notched specimens was predicted from the elastic-plastic-creep cyclic FEM analysis using the linear damage rule and the strain range partitioning rule. Both the life prediction methods predicted the creep-fatigue life within almost a factor of two scatter band.
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Sauzay, Maxime, und Mohamed Ould Moussa. „Comparison between Pile-Up Singularities and Stress Fields Induced by Thin Slip Bands. Application to the Prediction of Grain Boundary Microcrack Nucleation“. Key Engineering Materials 592-593 (November 2013): 61–66. http://dx.doi.org/10.4028/www.scientific.net/kem.592-593.61.
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Slip localization is widely observed in metallic polycrystals after tensile deformation, cyclic deformation or pre-irradiation followed by tensile deformation. Such strong deformation localized in thin slip bands induces local stress concentrations in the quasi-elastic matrix around, at the intersections between slip bands (SBs) and grain boundaries (GBs) where microcrack initiation is often observed. Since the work of Stroh, such stress fields have been mostly modeled using the dislocation pile-up theory which leads to stress singularities similar to the LEFM ones. The Griffith criterion has then been widely applied, leading usually to strong underestimations of the macroscopic stress to GB crack initiation. In fact, slip band thickness is finite: 20nm-1000nm depending on material, temperature and loading conditions. Then, many slip planes are plastically activated through the thickness, and not only one single atomic plane. To evaluate more realistic stress fields, numerous crystalline finite element (FE) computations have been carried out using microstructure inputs (slip band aspect ratio, crystal and GB orientation...). A strong influence of slip band thickness close to the slip band corner has been highlighted, which is not accounted for by the pile-up theory. But far away, the thickness has a negligible effect and the predicted stress fields are close to the one predicted by the pile-up theory. Closed-form expressions are deduced from the numerous FE computation results allowing a straightforward prediction of GB stress fields. Slip band plasticity parameters, such as length and thickness, as well as crystal orientation, GB plane and remote stress are taken into account. The dependence with respect to the various parameters can be understood in the framework of matching expansions usually applied to cracks with V notches of finite thickness. As the exponent of the GB stress close-field is only about one-half of the pile-up or LEFM crack one, the Griffith criterion may not be used for GB microcrack prediction in case of finite thickness. That is why finite crack fracture mechanics is used together with both energy and stress criteria. Taking into account SB finite thickness, t>0, leads to predicted remote stresses to GB microcrack initiation three to six times lower than the ones predicted using the to pile-up theory, in agreement with experimental data.
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Meza, Ramses, Guy Duncan, Konstantinos Kostas, Stanislav Kuzmin, Mauricio Florez, Tom Perrett und James Stewart. „Time-lapse seismic monitoring methodologies applied to the Pyrenees Field, offshore Western Australia“. APPEA Journal 55, Nr. 2 (2015): 412. http://dx.doi.org/10.1071/aj14047.
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Time-lapse dedicated 3D seismic surveys were acquired across the Pyrenees oil and gas field, Exmouth Sub-basin to map production-induced changes in the reservoir. Rock-physics 4D modelling showed that changes in pore pressure and fluid saturation would produce a time-lapse seismic response of sufficient magnitude, in both amplitude and velocity, to overcome time-lapse noise. The dominant observed effect is associated with gas coming out of solution. The reservoir simulation model forecasted that reservoir depletion would cause gas breakout that would impact the elastic properties of the reservoir. The effect of gas breakout can be clearly observed on the 4D seismic data as a change in both amplitude and velocity. The analysis of the seismic datasets was proven to be enhanced significantly by using inversion methodologies. These included a band-limited extended-elastic impedance (EEI) approach, as well as simultaneous 4D elastic inversion. These datasets, combined with rock physics modelling, enabled quantitative interpretation of the change in 4D seismic response which was a key tool for assisting with the infill well placement and field development strategy.
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Fan, Qingyang, Zhongxing Duan, Yanxing Song, Wei Zhang, Qidong Zhang und Sining Yun. „Electronic, Mechanical and Elastic Anisotropy Properties of X-Diamondyne (X = Si, Ge)“. Materials 12, Nr. 21 (31.10.2019): 3589. http://dx.doi.org/10.3390/ma12213589.
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The three-dimensional (3D) diamond-like semiconductor materials Si-diamondyne and Ge-diamondyne (also called SiC4 and GeC4) are studied utilizing density functional theory in this work, where the structural, elastic, electronic and mechanical anisotropy properties along with the minimum thermal conductivity are considered. SiC4 and GeC4 are semiconductor materials with direct band gaps and wide band gaps of 5.02 and 5.60 eV, respectively. The Debye temperatures of diamondyne, Si- and Ge-diamondyne are 422, 385 and 242 K, respectively, utilizing the empirical formula of the elastic modulus. Among these, Si-diamondyne has the largest mechanical anisotropy in the shear modulus and Young’s modulus, and Diamond has the smallest mechanical anisotropy in the Young’s modulus and shear modulus. The mechanical anisotropy in the Young’s modulus and shear modulus of Si-diamondyne is more than three times that of diamond as determined by the characterization of the ratio of the maximum value to the minimum value. The minimum thermal conductivity values of Si- and Ge-diamondyne are 0.727 and 0.524 W cm−1 K−1, respectively, and thus, Si- and Ge-diamondyne may be used in the thermoelectric industry.
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Atzori, Bruno, Mauro Ricotta und Giovanni Meneghetti. „Strain energy-and stress-based approaches revisited in notch fatigue of ductile steels“. MATEC Web of Conferences 165 (2018): 14009. http://dx.doi.org/10.1051/matecconf/201816514009.
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The constant amplitude, zero-mean stress, axial-fatigue behaviour of plain and bluntly notched AISI 304 L stainless steel specimens is investigated in terms of strain energy density. Concerning plain material, it was found that at the fatigue knee the plastic strain energy density is 1.49 times higher than the elastic strain energy density. In the authors’ opinion, the presence of plasticity at the fatigue knee is responsible for the unsuitableness of classical stress - based approaches to synthesise the fatigue behaviour of this material. On the contrary, the elastic-plastic strain energy density was found an efficient parameter to rationalise in a single scatter band fatigue data of plain and bluntly notched specimens. Based on this result, the classic stress-and the point stress-based approaches were revisited taking into account the presence of plasticity at the fatigue knee, by introducing an equivalent fully elastic material having a linear elastic strain energy density at the fatigue knee equal to that of the actual material. Accordingly, a coefficient of plasticity Kp was successfully introduced to modify the classical definition of fatigue strength reduction factor, Kf.
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Vettorello, Itauana, Daniele Michelin Paganotte, Adilson Sartorato, Vivian Fernandes Furletti de Góes, Andrea Aparecida de Aro, William Custodio und Cristina Maria Franzini. „Analgesic Efficacy of Cordia Verbenacea-based Gel in the Reduction of Pain Associated with Use of Separator Elastics/ Eficácia Analgésica do Gel à base de Cordia Verbenacea na Redução de Tinta Associada ao Uso de Elásticos Separadores“. Brazilian Journal of Development 7, Nr. 6 (28.06.2021): 63855–68. http://dx.doi.org/10.34117/bjdv7n6-661.
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Introduction: In Orthodontics separator elastics are used to create space for inserting the bands. This causes pain. Phytotherapy has been promising as a therapy. Objective. This double blind randomized clinical trial evaluated the level of pain due to the use of elastic separator (SE) after intraoral topical administration of Cordia verbenacea gel (CV). Methods. 50 volunteers received the SE on the mesial and distal surfaces of the maxillary first molars. In a blinded manner, 0.5 g of the gel was used in one hemi-arch, and placebo in the other hemi-arch on the free gingival margin of the first molar, every 8 hours, for 3 days. Pain was measured on a visual analog scale (VAS), before insertion of the SE (t0), immediately after (t1) and every hour after the following applications. Sensory analysis of the was performed for effects of taste and burning. Wilcoxon (comparison between sides) and Friedman and Nemenyi tests were performed for comparisons between times (α=0.05). Results. The pain was lower on the side that received the phytotherapeutic gel, from the first application until before the removal of the elastic (p 0.05). As regards the burning sensation, the experimental side had higher scores and 20% of the subjects considered the CV gel had an unpleasant taste. It was concluded that the use of the intrabucal topic of CV has an analgesic potential for pain resulting from the insertion of SE.
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Gosline, J. M., und R. E. Shadwick. „The mechanical properties of fin whale arteries are explained by novel connective tissue designs.“ Journal of Experimental Biology 199, Nr. 4 (01.04.1996): 985–97. http://dx.doi.org/10.1242/jeb.199.4.985.
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The aortic arch and the descending aorta in the fin whale (Balaenoptera physalus) are structurally and mechanically very different from comparable vessels in other mammals. Although the external diameter of the whale's descending thoracic aorta (approximately 12 cm) is similar to that predicted by scaling relationships for terrestrial mammals, the wall thickness:diameter ratio in the whale (0.015) is much smaller than the characteristic value for other mammals (0.05). In addition, the elastic modulus of the thoracic aorta (12 MPa at 13 kPa blood pressure) is about 30 times higher than in other mammals. In contrast, the whale's aortic arch has a wall thickness/diameter ratio (0.055) and an elastic modulus (0.4 MPa) that are essentially identical to those for other mammals. However, the aortic arch is unusual in that it can be deformed biaxially to very large strains without entering a region of high stiffness caused by the recruitment of fully extended collagen fibres. Chemical composition studies indicate that the elastin:collagen ratio is high in the aortic arch (approximately 2:1) and that this ratio falls in the thoracic (approximately 1:2) and abdominal (approximately 1:3) aortas, but the magnitude of the change in composition does not account for the dramatic difference in mechanical properties. This suggests that there are differences in the elastin and collagen fibre architecture of these vessels. The descending aorta contains dense bands of tendon-like, wavy collagen fibres that run in the plane of the arterial wall, forming a fibre-lattice that runs in parallel to the elastin lamellae and reinforces the wall, making it very stiff. The aortic arch contains a very different collagen fibre-lattice in which fibres appear to have a component of orientation that runs through the thickness of the artery wall. This suggests that the collagen fibres may be arranged in series with elastin-containing elements, a difference in tissue architecture that could account for both the lower stiffness and the extreme extensibility of the whale's aortic arch. Thus, both the structure and the mechanical behaviour of the lamellar units in the aortic arch and aorta of the whale have presumably been modified to produce the unusual mechanical and haemodynamic properties of the whale circulation.
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Sigalas, M. M., und N. Garcı́a. „Theoretical study of three dimensional elastic band gaps with the finite-difference time-domain method“. Journal of Applied Physics 87, Nr. 6 (15.03.2000): 3122–25. http://dx.doi.org/10.1063/1.372308.
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Seifoddini, Amir, Mahmoud Nili Ahmadabadi, Saeed Heshmati-Manesh, Mihai Stoica, Uta Kuehn und Jürgen Eckert. „The Effect of Microstructural Changes Induced by Annealing on Mechanical Properties of FeCoCrMoCBY Bulk Glassy Alloy“. Advanced Materials Research 488-489 (März 2012): 861–65. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.861.
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Bulk metallic glasses have interesting mechanical properties, such as high strength up to 5 GPa, high elastic strain and many other additional desirable properties. However, BMGs beyond the elastic region fail catastrophically on one dominant shear band and show little macroscopic plasticity in an apparently brittle manner. Nano-crystallized BMGs have been found to possess better ductility comparing with brittle parent BMGs. Annealing treatment of glassy alloys is a useful method to prepare bulk nano-crystalline alloys. In the present study, the crystallization trend of the FeCoCrMoCBY alloy which is claimed to have the best glass forming ability was studied in various times in temperature ranges of a) between Tg (glassy temp.) and Tx1 (first crystallization temp.), and b) between Tx1 and Tx2 (second crystallization temp.). The influences of different annealing time and temperatures on the microstructure and microhardness of Fe41Co7Cr15Mo14Y2C15B6BMG are reported in this paper.
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Duan, Hongxia, Peijun Li, Zhenwei Wang, Haixia Chen, Ting Wang, Weibing Wu und Xiaodan Liu. „Effect of 12-week pulmonary rehabilitation on cognitive function in patients with stable chronic obstructive pulmonary disease: study protocol for a single-center randomised controlled trial“. BMJ Open 10, Nr. 10 (Oktober 2020): e037307. http://dx.doi.org/10.1136/bmjopen-2020-037307.
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IntroductionCognitive impairment, an important complication in patients with chronic obstructive pulmonary disease (COPD), seriously affects self-management of the disease and quality of life (QoL). As an exercise-based intervention programme, pulmonary rehabilitation (PR)—especially aerobic exercise (mainly mind–body exercise) and resistance exercise (RE)—has been proposed for its potential effectiveness in improving cognitive function. However, there is still a lack of strong evidence for PR’s effectiveness. In this study, we expect to clarify the effects of pulmonary-based Qigong exercise and elastic band-based RE on cognitive function in patients with COPD and to fill in the relevant evidence blanks.Methods and analysisThis study is a single-centre randomised controlled trial with assessor and data analyst blinding. We will recruit 108 participants with stable COPD starting on 23 December 2019, and randomly allocate them into the pulmonary-based Qigong exercise group, elastic band-based RE group, pulmonary-based Qigong exercise and elastic band-based RE combined group, or control group at a 1:1:1:1 ratio. Participants in intervention groups will perform 30 min of exercise two times per day, 5 days a week, for 12 weeks. The primary outcome will be the global cognitive function as assessed by the Montreal Cognitive Assessment and auditory event-related potential P300. Secondary outcomes will include the specific cognitive domains—attention, memory, executive function, verbal fluency and mental-processing speed; psychological functions and QoL. Exploratory outcomes will include grey matter volume and levels of inflammatory mediators. Outcomes will be measured before and after the interventions.Ethics and disseminationEthics approval has been granted by the Ethics Committee of Yue-Yang Integrative Medicine Hospital, an affiliate of Shanghai University of Traditional Chinese Medicine, Shanghai, China (Grant No. 2019-141). Written informed consent will be obtained from each participant before any procedures are performed. The findings will be published in peer-reviewed journals and presented at academic conferences.Trial registration numberChiCTR1900026869; pre-results.
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Lee, Kang Il, und Suk Wang Yoon. „Acoustic band structures and time reversal of elastic waves in two- and three-dimensional phononic crystals“. Journal of the Korean Physical Society 68, Nr. 3 (Februar 2016): 398–402. http://dx.doi.org/10.3938/jkps.68.398.
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Rogers, Nicole L., Javier Gene, Alvaro Juesas, Pedro Gargallo, Andres Gene, Rosario Salvador, Juan C. Colado und Michael E. Rogers. „Squatting With Elastic Bands Facilitates More Weight Used And Time Under Muscle Tension“. Medicine & Science in Sports & Exercise 50, Nr. 5S (Mai 2018): 50. http://dx.doi.org/10.1249/01.mss.0000535246.15280.1f.
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Chibueze, TC. „Ab initio study of mechanical, phonon and electronic Properties of cubic zinc-blende structure of ZnO“. NIGERIAN ANNALS OF PURE AND APPLIED SCIENCES 4, Nr. 1 (19.08.2021): 130–38. http://dx.doi.org/10.46912/napas.190.
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The search for functional materials in opto-electronic devices is a major aspect of material research in contemporary times and a meta-stable structure of ZnO has been proposed as one such relevant materials. Herein the elastic constants, lattice dynamical and electronic properties of the cubic zinc-blende ZnO (ZB-ZnO) were studied at ambient pressure using the density functional theory method within the generalized gradient approximation. The result shows that ZB-ZnO is mechanically and dynamically stable, ductile and a direct band gap semiconductor and is very promising for opto-electronic applications. The results are in fair agreement with the available data in the literature.
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Bennett, Andrew, Matthew D'Orazio und Christopher Lueg. „Using Your Fingers to Think: Enabling Subjective Routing with a Rubber Band Metaphor“. International Journal of Software Engineering and Knowledge Engineering 25, Nr. 02 (März 2015): 397–413. http://dx.doi.org/10.1142/s0218194015400148.
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There is a class of complex problems where solutions must satisfy multiple subjective criteria, while meeting specific quantifiable constraints. Route planning for leisurely travel is an example of a problem in this class. Constraints including total available time, transit times, and one's budget and subjective interests determine whether a potential solution is acceptable to a prospective traveler. In this paper we present a route planning (routing) interface that metaphorically leverages various elastic properties of a rubber band to allow for playful interaction with the relevant constraints. Each of these properties — attenuation, tension, and color — were integrated into an experimental system and then investigated in a series of task-based evaluations. Our research shows this playful interaction enables potential travelers to explore the solution space in order to find a route that meets, not only the easily quantifiable constraints, but also their own subjective preferences.
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Emmerich, Helga, und Michael Korn. „Incorporation of attenuation into time‐domain computations of seismic wave fields“. GEOPHYSICS 52, Nr. 9 (September 1987): 1252–64. http://dx.doi.org/10.1190/1.1442386.
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The only numerically tractable way yet found to incorporate attenuation into numerical time‐domain computations of seismic wave fields is to approximate the viscoelastic modulus by a low‐order rational function of frequency. The coefficients of this function can be determined by the Padé approximation. Our test computations show, however, that this approximation generally is of poor quality. Therefore, we suggest a new approach which is based on the rheological model of the generalized Maxwell body, which has a modulus of the desired rational form. We choose the relaxation frequencies logarithmically equidistant in the frequency band of interest, and determine the weight factors by simple numerical curve fitting to an arbitrary Q law. This approach is superior to the method above both in accuracy and in computational efficiency. For most practical applications, approximations of orders 2 or 3 are sufficient. The computing time and memory requirements for a finite‐difference calculation are then approximately twice those of a purely elastic calculation. As a first application of the method, we compute SH channel waves in discontinuous coal seams with Q = 50 within the coal. The results show that the high‐ frequency Airy phase is strongly attenuated. This indicates that care has to be taken in comparing the results of purely elastic model calculations of the propagation of seam waves with experimental data.
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Triana, C. A., und F. Fajardo. „Dependence of some mechanical properties of elastic bands on the length and load time“. European Journal of Physics 33, Nr. 4 (26.04.2012): 771–84. http://dx.doi.org/10.1088/0143-0807/33/4/771.
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Hu, Yong, Jinfu Li, Tao Lin und Yaohe Zhou. „Plasticity improvement of Zr55Al10Ni5Cu30 bulk metallic glass by remelting master alloy ingots“. Journal of Materials Research 24, Nr. 12 (Dezember 2009): 3590–95. http://dx.doi.org/10.1557/jmr.2009.0430.
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The effect of repeated melting of master alloy ingots on the bending properties of Zr55Al10Ni5Cu30 bulk metallic glass (BMG) was investigated. The bending plasticity of Zr55Al10Ni5Cu30 BMG was found to be improved with the increased remelting times. When remelted 10 times, the BMG sample cast from the master alloy ingot undergoes bending, but it does not fracture even though the bending angle increases to 100°; the maximum bending stress and elastic strain remain almost constant. The bending plasticity improvement may be attributed to the fact that the increased remelting times result in more free volume and more disorder and homogeneous microstructure in the BMG, which favors the initial nucleation of profuse shear bands and reduces the probability of catastrophic fracture.
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Łygas, Krystian, Piotr Wolszczak, Grzegorz Litak und Paweł Sta̧czek. „Complex response of an oscillating vertical cantilever with clearance“. Meccanica 54, Nr. 11-12 (September 2019): 1689–702. http://dx.doi.org/10.1007/s11012-019-01033-z.
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Abstract We study the dynamics of an elastic inverted pendulum with amplitude limiters excited horizontally. This particular model corresponds to a class of systems where a clearance is present naturally as an effect of imperfect clamping or it is included to tailor the response. We explore the complex responses of the system for a fixed value of amplitude clearance. The simulation and experimental results are analysed by a 0–1 test, Fourier, and wavelet transforms. The results show that the system can vibrate with subharmonic solution where the main response frequency of a flexible beam is 3 times lower than the excitaion frequency. We claim that an inverted pendulum with imperfect clamping of mechanical resonator can be used in broad frequency band energy harvesting.
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Januševičius, Donatas, Audrius Sniečkus, Mantas Mickevičius, Danguolė Satkunskienė, Pornpimol Muanjai und Sigitas Kamandulis. „Integration of High Velocity Elastic Band for Hamstring Training in Pre-Season Routine of Football Players“. Baltic Journal of Sport and Health Sciences 4, Nr. 119 (25.02.2021): 31–39. http://dx.doi.org/10.33607/bjshs.v4i119.1017.
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Background. A need for other methods of hamstring strengthening are thus warranted with the main aim of reducing the risk of injury during the subsequent intense athletic activities. The study aimed to examine changes in hamstring strength in response to high velocity elastic band training when incorporated into regular training routine of football players.
Methods. Research participants were professional top level football players (age 23.1 ± 5.7 years; weight 77.2 ± 7.7 kg, training experience 14.1 ± 5.8 years). In the pre-season, in addition to their routine training, the experimental group performed hamstring curls at maximal intensity while lying prone three times per week for five weeks, while control group continued their routine training. Concentric knee torque at 60°/s and 180°/s angular velocities, countermovement jump height, 30m sprint running performance from standing and flying start, and knee flexion-extension movement frequency were measured before and after the 5 weeks of training.
Results. Hamstring curl frequency during lying prone increase by 10.5 % (p < .05) in the experimental group and did not change in the control group. Peak torque for knee flexion and knee extension, jump height and sprint running performance did not change significantly in any group (p > .05).
Conclusion. High velocity elastic band training incorporated into regular pre-season routine is beneficial for football players to increase their knee extension-flexion maximal movement frequency with no evident effects on strength, jump and sprint running performance. Results might be related with concurrent training during preparatory training phase of the pre-season when several physical capacities are being developed simultaneously.
Keywords: high speed movements; peak torque; sprint performance; prevention of hamstring injuries; knee flexion strength.
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Hussein, M. I., und R. Khajehtourian. „Nonlinear Bloch waves and balance between hardening and softening dispersion“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, Nr. 2217 (September 2018): 20180173. http://dx.doi.org/10.1098/rspa.2018.0173.
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The introduction of nonlinearity alters the dispersion of elastic waves in solid media. In this paper, we present an analytical formulation for the treatment of finite-strain Bloch waves in one-dimensional phononic crystals consisting of layers with alternating material properties. Considering longitudinal waves and ignoring lateral effects, the exact nonlinear dispersion relation in each homogeneous layer is first obtained and subsequently used within the transfer matrix method to derive an approximate nonlinear dispersion relation for the overall periodic medium. The result is an amplitude-dependent elastic band structure that upon verification by numerical simulations is accurate for up to an amplitude-to-unit-cell length ratio of one-eighth. The derived dispersion relation allows us to interpret the formation of spatial invariance in the wave profile as a balance between hardening and softening effects in the dispersion that emerge due to the nonlinearity and the periodicity, respectively. For example, for a wave amplitude of the order of one-eighth of the unit-cell size in a demonstrative structure, the two effects are practically in balance for wavelengths as small as roughly three times the unit-cell size.
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Gambassi, Bruno Bavaresco, Hélio José Coelho-Junior, Camila Paixão dos Santos, Ivan de Oliveira Gonçalves, Cristiano Teixeira Mostarda, Emanuele Marzetti, Samir Seguins Sotão, Marco Carlos Uchida, Kátia De Angelis und Bruno Rodrigues. „Dynamic Resistance Training Improves Cardiac Autonomic Modulation and Oxidative Stress Parameters in Chronic Stroke Survivors: A Randomized Controlled Trial“. Oxidative Medicine and Cellular Longevity 2019 (20.11.2019): 1–12. http://dx.doi.org/10.1155/2019/5382843.
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Stroke survivors are at substantial risk of recurrent cerebrovascular event or cardiovascular disease. Exercise training offers nonpharmacological treatment for these subjects; however, the execution of the traditional exercise protocols and adherence is constantly pointed out as obstacles. Based on these premises, the present study investigated the impact of an 8-week dynamic resistance training protocol with elastic bands on functional, hemodynamic, and cardiac autonomic modulation, oxidative stress markers, and plasma nitrite concentration in stroke survivors. Twenty-two patients with stroke were randomized into control group (CG, n=11) or training group (TG, n=11). Cardiac autonomic modulation, oxidative stress markers, plasma nitrite concentration, physical function and hemodynamic parameters were evaluated before and after 8 weeks. Results indicated that functional parameters (standing up from the sitting position (P=0.011) and timed up and go (P=0.042)) were significantly improved in TG. Although not statistically different, both systolic blood pressure (Δ=−10.41 mmHg) and diastolic blood pressure (Δ=−8.16 mmHg) were reduced in TG when compared to CG. Additionally, cardiac autonomic modulation (sympathovagal balance–LF/HF ratio) and superoxide dismutase were improved, while thiobarbituric acid reactive substances and carbonyl levels were reduced in TG when compared to the CG subjects. In conclusion, our findings support the hypothesis that dynamic resistance training with elastic bands may improve physical function, hemodynamic parameters, autonomic modulation, and oxidative stress markers in stroke survivors. These positive changes would be associated with a reduced risk of a recurrent stroke or cardiac event in these subjects.
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Zhang, Pengfei, Lingbo Kong, Peter Setlow und Yong-qing Li. „Characterization of Wet-Heat Inactivation of Single Spores of Bacillus Species by Dual-Trap Raman Spectroscopy and Elastic Light Scattering“. Applied and Environmental Microbiology 76, Nr. 6 (22.01.2010): 1796–805. http://dx.doi.org/10.1128/aem.02851-09.
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ABSTRACT Dual-trap laser tweezers Raman spectroscopy (LTRS) and elastic light scattering (ELS) were used to investigate dynamic processes during high-temperature treatment of individual spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis in water. Major conclusions from these studies included the following. (i) After spores of all three species were added to water at 80 to 90°C, the level of the 1:1 complex of Ca2+ and dipicolinic acid (CaDPA; ∼25% of the dry weight of the spore core) in individual spores remained relatively constant during a highly variable lag time (T lag), and then CaDPA was released within 1 to 2 min. (ii) The T lag values prior to rapid CaDPA release and thus the times for wet-heat killing of individual spores of all three species were very heterogeneous. (iii) The heterogeneity in kinetics of wet-heat killing of individual spores was not due to differences in the microscopic physical environments during heat treatment. (iv) During the wet-heat treatment of spores of all three species, spore protein denaturation largely but not completely accompanied rapid CaDPA release, as some changes in protein structure preceded rapid CaDPA release. (v) Changes in the ELS from individual spores of all three species were strongly correlated with the release of CaDPA. The ELS intensities of B. cereus and B. megaterium spores decreased gradually and reached minima at T 1 when ∼80% of spore CaDPA was released, then increased rapidly until T 2 when full CaDPA release was complete, and then remained nearly constant. The ELS intensity of B. subtilis spores showed similar features, although the intensity changed minimally, if at all, prior to T 1. (vi) Carotenoids in B. megaterium spores' inner membranes exhibited two changes during heat treatment. First, the carotenoid's two Raman bands at 1,155 and 1,516 cm−1 decreased rapidly to a low value and to zero, respectively, well before T lag, and then the residual 1,155-cm−1 band disappeared, in parallel with the rapid CaDPA release beginning at T lag.
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Liu, K., und J. Zhao. „Progressive Damage Behaviours of Triaxially Confined Rocks under Multiple Dynamic Loads“. Rock Mechanics and Rock Engineering 54, Nr. 6 (05.05.2021): 3327–58. http://dx.doi.org/10.1007/s00603-021-02408-z.
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AbstractInvestigation of rock progressive damage under static confinement and strain rates facilitates the generation mechanism of natural fault damage zones. A triaxial Hopkinson bar apparatus is used to perform dynamic triaxial compression tests to examine the damage and degradation process of rocks subjected to multiple impacts. Dynamic mechanical properties are determined under a static triaxial pre-stress of (30, 20, 10) MPa and multiple dynamic loadings, with the repetitive impact velocity of 27 m/s and strain rates from 50 to 150/s. The acoustic characteristics are identified by ultrasonic measurement to qualify the damage values. The micro-crack parameters, including crack area and volumes are detected using synchrotron X-ray micro-computed tomography (μCT) to characterize the progressive damage. In addition, the microcrack orientation, density and fractal dimension are analysed from thin section. Experimental results show that dynamic stress-strain curves can be divided to elastic, nonlinear deformation and unloading phases. Dynamic peak stress, Young’s modulus and ultrasonic wave velocity decrease with increasing impact times. The high frequency of ultrasonic wave is filtered by the induced microcracks. The progressive damage and evolution of fracture networks are associated highly with microcrack initiation, propagation, branching and coalescence. Shear bands are commonly generated in granite, and tensile cracks are dominant in marble, while sandstone is mainly failed by compaction and deformation band. The absorbed energy of rock increases nonlinearly with increasing crack surface and volume. Besides, microcracks propagate primarily along the maximum principal stress; the density and fractal dimension exhibit an anisotropic distribution controlled by true triaxial confinement and dynamic impacts.
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Wang, Haoan, Antonio Tota, Bilin Aksun-Guvenc und Levent Guvenc. „Real time implementation of socially acceptable collision avoidance of a low speed autonomous shuttle using the elastic band method“. Mechatronics 50 (April 2018): 341–55. http://dx.doi.org/10.1016/j.mechatronics.2017.11.009.
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Seo, Myong-Won, Sung-Woo Jung, Sung-Woo Kim, Jung-Min Lee, Hyun Chul Jung und Jong-Kook Song. „Effects of 16 Weeks of Resistance Training on Muscle Quality and Muscle Growth Factors in Older Adult Women with Sarcopenia: A Randomized Controlled Trial“. International Journal of Environmental Research and Public Health 18, Nr. 13 (23.06.2021): 6762. http://dx.doi.org/10.3390/ijerph18136762.
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This study examined the effects of resistance training on muscle quality, muscle growth factors, and functional fitness in older adult women with sarcopenia. Twenty-two older adult women aged over 65 with sarcopenia were randomly assigned to either resistance training (RT, n = 12) or non-exercise control group (CG, n = 10). The body weight-based and elastic band RT were performed three times a week, 60 min per session, for 16 weeks. Body composition and thigh muscle quality were estimated by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT), respectively. The muscle growth factors, including growth differentiation factor-8 (GDF-8), growth differentiation factor-15 (GDF-15), activin A, and follistatin, were analyzed via blood samples. Statistical analyses were performed using repeated measures multivariate analysis of variance (MANOVA), analysis of variance (ANOVA), and effect size (i.e., cohen’s d, partial eta square), and the significance level was set at 0.05. The RT group improved their functional fitness, grip strength, gait speed, and isometric muscle strength (p < 0.01, d > 0.99; large), while these variables did not change in the CG. An increase in intramuscular fat was only observed in the CG (p < 0.01, 1.06; large). Muscle growth factors such as follistatin were significantly increased in the RT (p < 0.05, 0.81; large), but other variables did not change following resistance training. Sixteen weeks of resistance training improved functional fitness and prevented age-related increases in intramuscular fat in the thigh area. However, there were only some changes in muscle growth factors, such as follistatin, suggesting that the effectiveness of resistance training on muscle growth factors is limited. Body weight-based and elastic band resistance training is an alternative training method for sarcopenia to minimize the age-related adverse effects on muscle function and quality.
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Mendes, Danielle Frota, José Euclides Nascimento, Adriano Francisco de Lucca Facholli, Maurício de Alencar Casa, Luciano da Silva Carvalho und Kikuo Sato. „Evaluation of plasticity and radiopacity of elastic separators by means of traction tests and radiography“. Dental Press Journal of Orthodontics 17, Nr. 6 (Dezember 2012): 23e1–23e10. http://dx.doi.org/10.1590/s2176-94512012000600008.
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INTRODUCTION: Elastic separators are widely used in the orthodontic clinic, in different sizes and thicknesses. Their function is to promote the separation between the teeth that will receive orthodontic bands, however, when subgingivally lost, they may cause periodontal problems and, ultimately, cause tooth extraction. OBJECTIVE: Concerned not only about their function but also about their properties, this experimental work was performed in order to evaluate, with a clinical perspective, the plasticity and radiopacity of the elastic separators, usually used in orthodontic clinic, through physical traction tests and radiographs. METHODS: Six different brands were analyzed and divided in two groups: extruded separators (American Orthodontics, GH, Morelli Blue and Morelli Green) and modular separators (Abzil, Dentaurum, GAC, Blue Modular Morelli and Green Modular Morelli). The plasticity was evaluated after physical traction tests, stretching the separators to 3 times their initial diameter. While the radiopacity was assessed using x-rays. RESULTS: When stretched to three times their inner diameter (ID), the extruded separators American Orthodontics, GH, Morelli Blue and Morelli Green and the modular ones Dentaurum, Morelli Blue Modular and Morelli Green Modular, presented elastic deformation, recovering their original inner diameter. The modular separators from Abzil and GAC showed permanent plastic deformation. With respect to radiopacity, the Abzil, American Orthodontics, Dentaurum, GAC and GH separators were radiopaque. CONCLUSION: Correlating the results concerning the plasticity and radiopacity, the separators which showed the most satisfactory results on both tests were, among the extruded separators, American Orthodontics and GH, and among the modular separators, GAC and Dentaurum.
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Matsuo, Tsuyoshi, Masayuki Nakada und Kazuro Kageyama. „Prediction of fiber-directional flexural strength of carbon fiber-reinforced polypropylene based on time–temperature superposition principle“. Journal of Composite Materials 52, Nr. 6 (19.06.2017): 793–805. http://dx.doi.org/10.1177/0021998317714638.
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This study verified that the time–temperature superposition principle for fiber-directional flexural strength can be applied to thermoplastic composites undergoing instantaneous fast phenomena such as impact failure and long-term phenomena such as creep failure, by constructing the time- and temperature-dependent master curve of relaxation modulus of thermoplastic resin. The master curve could be transformed to another master curve that predicts fiber-directional flexural strength of carbon fiber-reinforced thermoplastic composites based on the micro-buckling failure theory expressed mainly by the resin’s elastic modulus. The experimental results obtained from high-speed bending test, static bending test at various temperatures, and creep bending test demonstrated that kink band failure occurred on the compressive surface of the specimen at every test condition. This validation and verification related to thermoplastic composites made it possible to predict static and dynamic flexural strengths at arbitrary temperature and creep flexural strength.
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Secchi, Nicola, Costantino Fadda, Massimo Piccinini, Ivo Pinna, Antonio Piga, Pasquale Catzeddu und Simonetta Fois. „The Effects of Ovine Whey Powders on Durum Wheat-Based Doughs“. Journal of Food Quality 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/1789892.
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Two types of ovine whey powder, with different protein content, were added at increasing substitution rates to two types of semolina, one with strong and tenacious gluten and the other with weak and sticky gluten. For each dough the optimum mixing time and hydration level were calculated using the consistograph. The whey powder negatively affected the leavening volume of all doughs, at all percentages except the lowest one (5%), mainly because of its effects on the elastic component of gluten as measured with a stress relaxation test. Differences of the secondary structure of gluten proteins among samples were investigated by analyzing the amide I band in the Fourier transform infrared spectra of the dough. Weak and strong semolina showed a different relative percentage of α-helix, random coil, and β-sheet structures. The longer mixing times for dough formation when using semolina with strong gluten led to an increase in α-helices and random coils, which caused a worse leavening performance than the weak-gluten semolina.