Endurance Ratio Research Articles

Development of Dual Power Multirotor System

Vertical take-off and landing (VTOL) aircraft has good flight characteristics and system performance without runway. The multirotor system has been tried to expand into larger size for longer endurance or higher payload. But the motor power to endurance ratio has been limited. Due to the specific energy of gasoline being much higher than battery, introducing gasoline engine into multirotor system can be considered. This paper proposes a dual power multirotor system to combine a quadrotor using gasoline engines to provide major lift in shorter arm with another quadrotor using brushless DC motors to offer most controllable force with longer arm. System design, fabrication, and verification of the proposed dual power multirotor system development are presented. Preliminary flights have achieved 16 kg payload for long endurance flight. This is useful for various applications with advanced improvements.

Isokinetic trunk flexion–extension protocol to assess trunk muscle strength and endurance: Reliability, learning effect, and sex differences

PurposeThe purpose of this study was to examine the reliability and the learning effect of an isokinetic trunk flexion–extension protocol designed to simultaneously assess trunk muscle strength and endurance. In addition, the effect of the participants' sex on the reliability data was examined. MethodsFifty-seven healthy and physically active young men (n = 28) and women (n = 29) performed the isokinetic protocol 5 times, separated by a week between each of the first 4 sessions and by a month between the last 2 sessions. The protocol consisted of performing 4 trials of 15 maximum flexion–extension concentric exertions at 120°/s (range of trunk motion = 50°). The absolute and relative peak torque and total work were calculated to assess trunk flexion and extension strength. In addition, endurance ratio, modified endurance ratio, fatigue final ratio, recovery ratio, and modified recovery ratio variables were used for the assessment of trunk muscle endurance in both directions. ResultsRegarding the absolute reliability, no relevant changes were found between paired-comparison sessions for most strength and endurance variables, except for total work and relative total work variables in the flexion movement in both sexes. In addition, the typical error of the isokinetic variables was lower than 10% in both males and females, and minimum detectable changes ranged from 7% to 20%, with a tendency to be higher in females and in endurance variables. The strength variables showed high-to-excellent intraclass correlation coefficients (ICCs; >0.74); however, for the endurance variables only the endurance ratio and the modified endurance ratio obtained moderate-to-high ICC values (0.57 < ICC < 0.82). In addition, the analysis of the variance reported no significant differences between consecutive pairs of sessions for most variables in both sexes. ConclusionOverall, these findings provide clinicians, trainers, and researchers with a 10-min single-session protocol to perform a reliable muscle strength and endurance evaluation of trunk flexor and extensor muscles, all within the same protocol.

Differential Strength and Endurance Parameters of the Craniocervical and Cervicothoracic Extensors and Flexors in Healthy Individuals.

This study examined isometric strength (maximal voluntary contraction [MVC]) and endurance of cervical flexor and extensor muscles in healthy individuals at the craniocervical (CC) and cervicothoracic (CT) axes. MVC and endurance measures (time to task failure in seconds [s]) at 50% MVC were recorded in 4 directions (CC flexion, CC extension, CT flexion, and CT extension) in 20 males and 20 females, and 6 strength and endurance ratios were calculated. The findings showed that the cervical extensor muscles are not only much stronger than the flexors (1.3-2 times greater MVC), but also have greater capacity for endurance (2-2.4 times greater). While males produced significantly greater MVC recordings than females (P < .003), strength ratios (P > .06) and endurance measures (P > .11) were similar. Endurance ratios were also similar except the CT extension to CC flexion ratio, which was significantly larger in females compared with males (P = .03). These findings demonstrate that substantial but normal variation exists in strength and endurance parameters between cervical flexor and extensor muscles. This is informative to clinicians when evaluating the performance of these neck muscles or when deciding on exercise parameters (eg, load, duration) when training their performance.

Acute Effects of a Weight Loss Supplement on Endurance, Heart Rate, and Respiratory Exchange Ratio

PURPOSE: The purpose of this study was to examine the acute effects of a weight loss supplement on endurance, heart rate (HR), and respiratory exchange ratio (RER). METHODS:Thirty-one (athletic and non-athletic) male and female subjects (male=15, female=16), between the ages of 18 and 40, were familiarized with the study protocol and performed the Bruce protocol on the first day. The study utilized a randomized, double blind, crossover, in which a subject would be given a placebo or supplement on two separate days. Each condition began with the subject reaching a hydration status at or below 1.010. Once the hydration levels were reached, the subject would receive an envelope, containing either supplement or placebo, to open and ingest 3 capsules. 30 minutes after the subject ingested the capsules, they would run on a treadmill, at 80% VO2 Max, until volitional fatigue. HR and RER were collected and monitored every three minutes during the running session. When the subject reached volitional fatigue, running time was recorded. RESULTS:There were no significant condition*time and condition*category interactions, but there were significant condition (p=.03) and time (p=.01) main effects for RER. There were also significant condition (p=.03) main effects on the endurance for non-athletic females. Significant condition*category interaction (p<.01) and time main effects (p<.01) were observed for HR. CONCLUSIONS:The results showed that the weight loss supplement caused a significantly higher RER during the first 15 minutes of exercise. This may have been caused by the ingestion of caffeine resulting in vasoconstriction of the blood vessels surrounding the adipose tissue, causing a decrease in fatty acid mobilization, and therefore eliciting an increase in glycogen use. The non-athletic females may have had a greater response, which could be due to the greater caffeine to body weight ratio when compared to males and a lower daily caffeine ingestion than their athletic counterparts.

Effect of Adding Mixture of Sand Dunes and Emulsified Asphalt on Engineering Properties of Gypseous Soil

This research includes an examination of direct shear to find cohesion gypsum soil (C) and the angle of friction (Φ) internal to that soil and also conducted screening collapse to find the amount of collapse (Cp) and examination of endurance Californian rate (CBR TEST) in addition to the tests Mark Forums Read this soil. Where that all these tests were conducted on soils is confused and soil confused untreated soil confused address mixture} (2%, 3%), (2% 0.6%), (2% 0.9%), (2% .12%), (4 % 0.3%), (4%, 0.6%), (4%, 0.9%), (4%, 0.12%), (6% 0.3%), (6%, 6%), (6%, 9%), (6% .12%) (8% 0.3%), (8%, 6%), (8% 0.9%), (8% 0.12%) {emulsion asphalt and sand dunes on respectively. The results showed that the strength of cohesion Azdadh worth about (43%) at the optimum proportions of emulsion asphalt and sand dunes that are (6% emulsion asphalt 0.9% sand dunes mixture treatment) compared to the untreated soil confused. The value of the friction angle also increased its value by 33% at the optimum proportions of the mixture of asphalt emulsion and sand dunes that are (6% asphalt emulsion 0.12% sand dunes treatment) compared to the untreated soil confused. As for the breakdown in the soil in the gypsum soil used in research has decreased by 59% when using the optimal ratios of emulsified asphalt and sand dunes mixture (6% asphalt emulsion 0.12% sand dunes) compared to the untreated soil confused. As well as increased endurance ratio Californian by (27%) for a breakthrough at 2.5 mm and also this figure increased by 19% for a breakthrough at 5 mm and when treatment for optimization of emulsion asphalt and sand dunes mixture (6% Asphalt Emulsion 0.12% sand dunes) compared to soil Jbsh confused untreated .

Tensile and Fatigue Evaluation of a Glass Reinforced Recycled Nylon Blend: Effect of Polypropylene Contamination

ABSTRACTTensile strength was measured on 30 wt% glass fiber-reinforced postconsumer waste and postindustrial waste recycled nylon blends. Fatigue tests were performed under load control at a stress ratio of 0.1 at temperatures of 24 and 120°C. It was found that increasing temperature led to a significant decrease in both tensile strength and fatigue life. For unwelded postindustrial waste/postconsumer waste blends, the endurance ratio was approximately 50% regardless of the temperature. For welded postindustrial waste/postconsumer, a similar endurance ratio was observed at room temperature, but it decreased to 33% at 120°C due to the presence of polypropylene found in the postconsumer component.

Memristive devices from porous silicon – ZnO/VO2 nanocomposites

As metal oxides act as an active media for oxygen vacancies transport after their infiltration/confinement in the submicron porous structure, we report the memristive device fabrication from nanostructured porous silicon – metal oxide (ZnO and VO2) composites. Scanning electron microscopy and X-ray diffraction were used for morphological and structural characterization, respectively. Predominant crystal phase of metal oxides was found to be wurtzite for ZnO and monoclinic for VO2. Electrical characterization reveals that both devices present symmetrical zero-crossing pinched hysteresis curves, typical of memristive systems. Although both the devices reveal significant endurance and stable switching ratio, ZnO-based device exhibits relatively better stability and 86% higher resistive switching ratio with respect to VO2-based device. The proposed memristive devices have potential applications as practical and economical structures that could be integrated in current silicon based microtechnology.

Fatigue properties of vibration‐welded postindustrial waste nylon with glass fibers at room and elevated temperatures

The effect of temperature on the tensile and fatigue strength of vibration‐welded and unwelded postindustrial waste nylon 6 reinforced with 30 wt% glass fiber (PIWGF) was experimentally examined, and the results were compared to those obtained from a 30 wt% glass fiber reinforced prime nylon 6 compound (PAGF) from a previous study. Fatigue tests were performed under sinusoidal constant amplitude tension‐tension load at a stress ratio of R = 0.1 and within the frequency range of 2–10 Hz at temperatures from 24 to 120°C. Stress levels from just under the tensile strength down to the run‐out point at 5 million cycles were used. It was found that increasing temperature led to a significant decrease in both tensile strength and fatigue life. For PIWGF, there was ∼20% strength reduction under both static tensile and cyclic loading as compared to PAGF. For both welded and unwelded PIWGF, the endurance ratio; i.e., the ratio of fatigue strength to static tensile strength, was ∼45% regardless of the temperature. The fatigue notch factor (Kf) was between 1.4 and 1.8 for all test temperatures examined. POLYM. ENG. SCI., 55:799–806, 2015. © 2014 Society of Plastics Engineers

Effect of temperature on fatigue strength of vibration welded and unwelded glass reinforced nylon 6

The effect of temperature on the tensile and fatigue strength of vibration welded and unwelded 30wt% glass fiber reinforced nylon 6 (PA6GF) was experimentally examined. Fatigue tests were performed under sinusoidal constant amplitude tension–tension load at a stress ratio of R=0.1 and within the frequency range of 2–10Hz. Stress levels from just under the tensile strength down to the run-out point, at 5 million cycles, were used. It was found that increasing temperature led to a significant decrease in both tensile strength and fatigue life. However, it was also noted that for both welded and unwelded PA6GF, the endurance ratio, i.e., the ratio of fatigue strength to static tensile strength, was approximately 45% regardless of the temperature. The fatigue notch factor (Kf) lies between 1.5 and 1.75 regardless of test temperature.

Forming-free resistive switching characteristics of 15 nm-thick multicomponent oxide

Resistive switching (RS) characteristics and mechanism of multicomponent oxide (MCO) memory device are studied. MCO based on an amorphous (ZrCuAlNi)Ox active layer with a thin thickness of ∼15 nm is sputter deposited without substrate heating or post-annealing. The device shows forming-free unipolar RS properties of low operation voltage (&amp;lt;1.7 V), long retention time, good endurance, and resistance ratio. The RS property is considered to be dominated by the filamentary conduction due to the presence of oxygen vacancies in the grain boundary-free structure.

Shoulder Rotator Cuff Balance, Strength, and Endurance in Young Swimmers During a Competitive Season

The purpose of this study was to analyze the effects of a competitive swim season on the strength, balance, and endurance of shoulder rotator cuff muscles in young swimmers. A repeated measures design was used with 3 measurements performed during the swim season. A swimmers group (n = 20) of young men with no dry land training and a sedentary group (n = 16) of male students with the same characteristics (age, body mass, height, and maturational state) were evaluated. In both groups, the peak torque of shoulder internal rotator (IRt) and external rotator (ERt) was assessed during preseason, midseason (16 weeks), and postseason (32 weeks). Concentric action at 60 and 180°·s(-1) was measured using an isokinetic dynamometer. The ER/IR strength ratios and endurance ratios were also obtained. At 60°·s(-1), there were significant training effects in the IRt strength and ER/IR ratio on both shoulders. This trend was the same throughout the competitive season. The same trend was present at 180°·s(-1) because the training effects are seen primarily in IRt and ER/IR ratios. With respect to endurance ratios, within-group data were similar in ERt and IRt for both shoulders, with no significant differences between moments. However, between-group differences occurred mostly in the IRt. Results suggest that a competitive swim season favors the increase of muscular imbalances in the shoulder rotators of young competitive swimmers, mainly because of increased levels of IRt strength and endurance that are proportionally larger than those of their antagonists. A compensatory strength training program should be considered.

Evaluation of the results obtained from isokinetic muscle test in patients with primary fibromyalgia syndrome

The aim of this study was to investigate whether the subjective muscle skeleton complaints of patients with fibromyalgia have an objective basis and the usability of muscle test results for diagnosis of fibromyalgia. 20 patients having primer fibromyalgia syndromes (PFS) who conforms to the criteria suggested by the American Rheumatism Association and a control group of 20 healthy people performed isokinetic muscle test over the right quadriceps and hamstring muscle group by Cybex 6000. In this study, maximum torque (MT), the ratio of maximum torque over body weight (MTWA), torque acceleration energy (TAE), total work (TW), set total work (STW), average power (AP) and endurance ratio (ER) were measured for muscle performance. A significant difference was found between the tests showing the muscle performance between the patients and the control group except the ER parameter. This difference was smaller in patients with fibromyalgia. As a result, it is decided that the objective low values in the muscle tests which are observed in patients with fibromyalgia are significant and isokinetic quantitative muscle test is a quite reliable method which can assist the doctor for the diagnosis of fibromyalgia. There exists a connection between the general fatigue and pain complaints of the patients with PFS and muscle deficiency. This muscle deficiency can be measured numerically by objective isokinetic methods. We argue that these measures should be utilized in the diagnosis and follow-up of patients. Key words: Isokinetic testing, fibromyalgia, muscle

Kinesio Taping and the Circulation and Endurance Ratio of the Gastrocnemius Muscle

Kinesio Tex tape is a therapeutic tape that is applied with the Kinesio-taping (KT) method and is theorized to increase circulation and subsequently improve muscle function. However, little research has been conducted to determine how KT affects performance. To determine the effect of KT on muscular endurance ratio, blood flow, circumference, and volume of the gastrocnemius muscle. Randomized controlled clinical trial. Research laboratory. Patients or Other Participants: Sixty-one healthy, active people (23 men, 38 women; age = 19.99 ± 8.01 years, height = 169.42 ± 23.62 cm, mass = 71.53 ± 36.77 kg) volunteered to participate. They were assigned randomly to 1 of 3 groups: treatment KT, sham KT, and control. Tape was applied based on group assignment. The treatment KT group received the ankle-tape technique as described in the KT manual. The sham KT group received 1 strip of Kinesio Tex tape around the circumference of the proximal gastrocnemius muscle. The control group did not receive tape application. The dependent variables were blood flow in blood perfusion units, volume of water displacement in milliliters, circumference of the gastrocnemius muscle in centimeters, and endurance ratio in joules measured before, 24 hours after, and 72 hours after the intervention. Separate repeated-measures analyses of variance were conducted for each dependent variable. We found no group-by-test day interaction for endurance ratios (F(4,116) = 1.99, P = .10). Blood flow, circumference, and volume measurements also yielded no differences among groups (F(2,58) range, 0.02-0.51; P > .05) or test days (F(2,116) range, 0.05-2.33; P > .05). We found KT does not enhance anaerobic muscle function measured by endurance ratio. The KT also did not affect circulation or volume of the gastrocnemius muscle in a healthy population.

Intrinsic and extrinsic resistive switching in a planar diode based on silver oxide nanoparticles

Resistive switching is investigated in thin-film planar diodes using silver oxide nanoparticles capped in a polymer. The conduction channel is directly exposed to the ambient atmosphere. Two types of switching are observed. In air, the hysteresis loop in the current–voltage characteristics is S-shaped. The high conductance state is volatile and unreliable. The switching is mediated by moisture and electrochemistry. In vacuum, the hysteresis loops are symmetric, N-shaped and exhibit a negative differential resistance region. The conductance states are non-volatile with good data retention, programming cycling endurance and large current modulation ratio. The switching is attributed to electroforming of silver oxide clusters.

육상 단거리 선수와 장거리 선수의 체간과 하지의 근기능 및 근전도 비교 분석

The purpose of this study was to compare and analyze muscle function and EMG of the trunk and the lower extremity in short and long distance athletes and in order to determine difference in peak torque per unit weight, muscle power per unit weight, endurance ratio, and %MVIC classified by muscle. For that purpose, isokinetic muscle function tests for waist, knee, and ankle joints and EMG measurements for the trunk and the lower extremity muscle with running motion were conducted for 7 short and long distance high school athletes respectively. The study over muscle function of waist, knee, and ankle joints indicates that peak torque per unit weight of short distance athletes is higher than that of long distance athletes in extension and flexion of waist joint, plantar flexion of right ankle joint, and dorsi flexion of left ankle joint. In case of the muscle power per unit weight of short distance athletes is also higher than long distance athletes in waist, knee, and ankle joints. No difference in endurance ratio of waist, knee, and ankle joints between the two groups was founded. The results of the test over EMG of the trunk and the lower extremity show that %MVIC of erector spinae, rectus femoris, vastus medialis, vastus lateralis, and tibialis anterior is higher than that of long distance athletes in support phase. The above results proved to be the same in flight phase except for %MVIC of medial gastrocnemius. In other words, %MVIC of medial gastrocnemius for short distance athletes turned out to be higher than that of long distance athletes in flight phase.

Is PPARα intron 7 G/C polymorphism associated with muscle strength characteristics in nonathletic young men?

Peroxisome proliferator-activated receptor alpha (PPARα), a ligand-dependent transcription factor, regulates fatty acid metabolism in heart and skeletal muscle. The intron 7 G/C polymorphism (rs4253778) has been associated with athletic performance. The rare C-allele was predominant in power athletes, whereas the G-allele was more frequent in endurance athletes. In the present study, we investigated the association between this polymorphism and strength characteristics in nonathletic, healthy young adults (n = 500; age 24.2 ± 4.4 years). Knee torque was measured during concentric knee flexion and extension movements at 60°/s, 120°/s, and 240°/s during 3, 25, and 5 repetitions, respectively. Also, resistance to muscle fatigue (i.e. work last 20% repetitions/work first 20% repetitions *100) was calculated. Differences in knee strength phenotypes between GG homozygous individuals and C-allele carriers were analyzed. The polymorphism did not influence the ability to produce isometric or dynamic knee flexor or extensor peak torque during static or dynamic conditions in this population (0.23 < P < 0.95). Similar results were found for the endurance ratio, a measure for resistance to muscle fatigue. In conclusion, the PPARα intron 7 G/C polymorphism does not seem to influence strength characteristics in a nonathletic population.

Introduction of an exponential formulation to quantify the electrical endurance of micro-contacts enduring fretting wear: Application to Sn, Ag and Au coatings

Abstract The massive use of electronic control in automotive, plane and energy systems requires the extensive application of in board low current electrical connectors. Subjected to vibrations, the electrical contacts endure severe fretting wear damage (i.e. wear of contacts induced by oscillating small amplitude displacements). One consequence of this fretting wear damage is that oxide debris are formed and maintained within the interface, decaying the electrical transmission of information. To prevent this critical damage, various soft and thin electrolytic coatings like Sn, Ag and Au layers are usually applied. In order to better understand the damage processes and provide a quantitative strategy to select the coating palliatives, an original approach coupling representative experiments and analytical models is introduced. Using a representative micro-fretting system, the electrical resistance evolution is shown to be mainly controlled by the applied displacement and sliding condition. It is confirmed that below a threshold displacement amplitude, related to a stabilised partial slip condition, the electrical endurance is infinite. Above this threshold, when full gross slip conditions are running, a finite endurance behaviour is observed. The electrical endurance is then controlled by the interfacial oxide debris layer formation and the nature of the coating. For non-noble coatings, like Sn, the electrical failure comes about as soon as an oxide debris layer, the so-called “third body” is trapped within the interface, while the endurance of noble and semi-noble materials (i.e. Au, Ag), which is significantly greater, is controlled by the progressive decrease of noble element concentrations in the third body layer and the related increase of its current resistivity. Finally, simple and basic exponential formulations are introduced to rationalise the global electrical endurance of “connector like” micro-contacts subjected to fretting wear. Using this formulation, an endurance ratio is developed to compare the endurance performance of the different coating palliatives.

アルミニウム合金板における&lt;br&gt;メカニカルクリンチングされた接合部の強度特性と向上法

The static and fatigue strengths of mechanically clinched, self pierce riveted and resistance spot welded joints in aluminium alloy A5052-H34 sheets were investigated. In the static tension-shearing test, self pierce riveted, resistance spot welded and mechanical clinched joints were tested in order of the maximum load. The endurance ratio of the sheets joined by the mechanical clinching and self pierce riveting were larger than that of the sheets joined by resistance spot welding owing to the work-hardening and slip at the interface between the sheets, i.e. the fatigue characteristic of mechanical joining processes was better than that of the welding processes involving metallurgical bonding. To increase the maximum joint load for mechanical clinching, a step punch was proposed. In the mechanical clinching using the step punch, the wall thickness in the side wall of the punch was increased by the compression of the step. The maximum static load and endurance ratio for mechanical clinching using a step punch were increased by 21% and 45%, respectively.

Different Interface Role in CuOx Based RRAM

For the embedded application of resistive switching memory using CuOx films, the differences in interfacial chemical interaction may affect filament formation and rupture processes near the electrode and hence alter the resistive switching behaviors. Al/CuxO/Cu and TaN/CuxO/Cu devices were fabricated and investigated for the memory switching characteristics, data retention and mechanism, respectively. The results show better stability, preferable endurance, and larger resistance ratio for Al electrode. An interface AlOx layer is detected by transmission electron microscopy and Auger electron spectroscopy. This layer can strongly affect the movement of oxygen vacancies. TaON was observed for TaN/CuxO/Cu device at the anode interface by X-ray photoelectron spectroscopy and transmission electron microscopy, which is believed to play a key role in the resistance transition. The physics behind this phenomenon of reactive top-electrode is revealed. The interface filament/charges trapping dominated model is proposed to clarify the electrical characteristics of the top-electrode/oxide reactions

Assessment of core stability in Indian women wrestling team and its relationship to low back pain

Wrestling is a dynamic and highly demanding sport. Core stability is predominantly maintained by dynamic function of muscular elements, which act as a bridge between upper limbs and lower limbs...