Ratio Of Maximum Force Research Articles

Dynamic response of single-bucket foundation in clay under vertical variable amplitude cyclic loadings

The application of multi-bucket foundation has an increasing trend in deeper water. The horizontal dynamic response of multi-bucket foundation mainly depends on the vertical cyclic behavior of single bucket in this multi-bucket foundation. In order to investigate the vertical dynamic response of single bucket foundation, a series of 1g model tests were carried out under vertical cyclic loadings in over-consolidated clay. Test results show that the vertical displacement of model bucket increases and the stiffness of bucket-soil decreases with the increase of cyclic loading level parameter ζb, which is defined as the ratio of maximum force in loading cycle and static ultimate capacity. The vertical capacity increased by about 23% and 19.5% after constant amplitude unidirectional loading and variable amplitude loading, respectively. And the vertical capacity remains unchanged after constant amplitude bi-directional loading. The vertical displacement and stiffness of bucket-soil increase with the increase of cyclic times N. Superposition theory was applied to express the vertical displacement and stiffness of bucket-soil under vertical variable amplitude cyclic tests. The stiffness law was also analyzed using the spring model. The study on the vertical behavior of single-bucket foundation can provide some reference for the design of multi-bucket foundation.

Analysis of the rheological behavior of polymer modified asphalt binders subjected to force-ductility test

The basic measurement method used to assess the properties of polymer modified bitumens is a tensile test. In this study, PMB specimens of various elastomer SBS content (in the range from 3% to 9%), but a similar penetration, determined at 25°C were tested. In order to evaluate the rheological properties and temperature susceptibility, the Force-Ductility Tests were conducted at 0, 10 and 25°C. On the basis of the obtained results, the values of the maximum force ratio (MFR) were calculated. It could characterize the efficiency of bitumen modification by elastomer addition. Moreover, on the basis of the first tensile force maximum determined at 0 and 25°C, values of the maximum force index (MFI) were calculated. This parameter may be an alternative to commonly used penetration index.

Effect Of Puberty And Gender On Landing Force And Jump Height

PURPOSE Neuromuscular performance increases rapidly in males throughout pubertal development. A similar neuromuscular spurt is not typically found in females during the same stages of puberty. The hypothesis was that there would be no differences throughout pubertal tanner stages in neuromuscular performance in females while males would show a greater vertical at each stage of development. METHODS 275 middle school and high school athletes volunteered to participate in this study (87 females, 188 males). Subjects were recruited from preseason physical screening. Pubertal development (Tanner Stage) was assessed by trained physicians. Only those athletes who were classified as pubertal through post pubertal (Tanner Stages 2–5) were included. Each subject performed 2 drop vertical jumps (DVJ) from a box height of 31cm (Ford 2003). They were instructed to drop off the box, land and immediately perform a maximal vertical jump. A portable force platform was used to collect the landing from the box and the landing after the vertical jump (AccuPower, AMTI). Maximum vertical ground reaction force (MVGRF) was calculated at three different phases, drop landing (DL), drop take-off (DT), and vertical landing (VL). Maximum vertical jump height (V) was also calculated from each trial. The ratio of the MVGRF (DL/DT) at the eccentric and concentric phases was calculated. A 2 ± 4 ANOVA (Gender*TannerStage) was utilized. RESULTS There was no difference in vertical jump height (V) throughout the developmental stages in females, males increased their vertical jump height by 16.3%, 13.4% and 7.9% at each stage of pubertal development (p = 0.002). The ratio DL/DT was decreased in males throughout pubertal stages while females showed no change (p = 0.047). The ratio of maximum force during the landing after the vertical to the maximum vertical jump (VL/V) decreased in males throughout pubertal stages while females had no change (p = 0.024). CONCLUSIONS These findings confirm the absence of a neuromuscular spurt in females and its presence in males. Lack of the neuromuscular spurt and force attenuation may play a role in the increased risk of ACL injury in female athletes. Injury prevention programs improve neuromuscular control and reduce ACL injuries in young females. The divergence in ACL injury rates between male and female athletes begin around age 12, when the majority of females are pubertal and their impact forces fail to be attenuated.

Effect Of Puberty And Gender On Landing Force And Jump Height

PURPOSE Neuromuscular performance increases rapidly in males throughout pubertal development. A similar neuromuscular spurt is not typically found in females during the same stages of puberty. The hypothesis was that there would be no differences throughout pubertal tanner stages in neuromuscular performance in females while males would show a greater vertical at each stage of development. METHODS 275 middle school and high school athletes volunteered to participate in this study (87 females, 188 males). Subjects were recruited from preseason physical screening. Pubertal development (Tanner Stage) was assessed by trained physicians. Only those athletes who were classified as pubertal through post pubertal (Tanner Stages 2–5) were included. Each subject performed 2 drop vertical jumps (DVJ) from a box height of 31cm (Ford 2003). They were instructed to drop off the box, land and immediately perform a maximal vertical jump. A portable force platform was used to collect the landing from the box and the landing after the vertical jump (AccuPower, AMTI). Maximum vertical ground reaction force (MVGRF) was calculated at three different phases, drop landing (DL), drop take-off (DT), and vertical landing (VL). Maximum vertical jump height (V) was also calculated from each trial. The ratio of the MVGRF (DL/DT) at the eccentric and concentric phases was calculated. A 2 ± 4 ANOVA (Gender*TannerStage) was utilized. RESULTS There was no difference in vertical jump height (V) throughout the developmental stages in females, males increased their vertical jump height by 16.3%, 13.4% and 7.9% at each stage of pubertal development (p = 0.002). The ratio DL/DT was decreased in males throughout pubertal stages while females showed no change (p = 0.047). The ratio of maximum force during the landing after the vertical to the maximum vertical jump (VL/V) decreased in males throughout pubertal stages while females had no change (p = 0.024). CONCLUSIONS These findings confirm the absence of a neuromuscular spurt in females and its presence in males. Lack of the neuromuscular spurt and force attenuation may play a role in the increased risk of ACL injury in female athletes. Injury prevention programs improve neuromuscular control and reduce ACL injuries in young females. The divergence in ACL injury rates between male and female athletes begin around age 12, when the majority of females are pubertal and their impact forces fail to be attenuated.

Control of manipulative forces during unimanual and bimanual tasks in patients with Huntington’s disease

The aim of the study was to investigate grip-load force regulation in Huntington's disease (HD) patients as compared to control subjects during the performance of a manipulative task that required rhythmical unimanual or bimanual isodirectional/non-isodirectional actions in the sagittal plane. Results showed that the profile of grip-load ratio force was characterized by maxima and minima that were attained at upward and downward hand positions, respectively. Minimum force ratio was higher in patients than in controls, which points to an elevated baseline that may be related to the inherent bradykinesia observed in HD. Maximum force ratio was also increased in patients, but this effect depended on the performance condition, with largest amplifications occurring during non-isodirectional movements. The latter rescaling may be associated with the complexity of the coordination mode and its asymmetrical load characteristics. In addition, the temporal delay between the grip and load force peaks was augmented in patients versus controls, indicating a disturbed coupled activation of both forces. Furthermore, the interval was largest during non-isodirectional movements followed by isodirectional and unimanual movements, which denotes that the grip-load force coupling deteriorated as a function of coordinative complexity. Together, these data indicate a deficit in the grip-load force constraint due to HD and illustrate the degrading effect of striatal dysfunction on (bi)manual manipulative function.

Localized Deformation Using Higher Order Stress/Strain Theory

A material is considered which consists of rough interacting blocks. The interaction, which is expressed in terms of the ratio of the normal and tangential force at the contact points of the blocks, is pure frictional if a certain maximal force ratio is reached, and elastic otherwise. The shape of the blocks is determined by the double shearing geometry. Failure modes for this material depend on the thickness of the slip band. The investigation is relevant to granular soils and rocks.

Responses of isolated canine airways to electric stimulation and acetylcholine.

Contractility of tracheal smooth muscle strips and spiral strips of intrapulmonary airways 5 mm and 1.5 mm in diameter was studied in organ baths. Acetylcholine (ACh) sensitivity of canine airways closely resembled that of other species, and concentration-response curves for this drug were similar for all three preparations. Electric field stimulation (ES) elicited sustained contractions and, in contrast to guinea pig and human airways, never produced relaxations below the base line. Atropine antagonized the responses to both ES and exogenous ACh whereas tetrodotoxin abolished the response to supramaximal ES without altering ACh concentration-response curves. Thus, ES contracts airway smooth muscle via release of neurotransmitter from autonomic nerve endings whereas exogenous ACh acts directly on smooth muscle cells. The ratio of maximal force produced by ES to that produced by ACh decreased significantly from the trachea to the 1.5-mm airways. The latter result suggested that either the innervation of airway smooth muscle or the type of smooth muscle intercellular contacts, or both, vary depending on location within the tracheobronchial tree.