Landing Angle Research Articles

Jakarta Asian Games Men's 20km Walking Championship and Runnerup Comparative Study of Technologies

As a competitive event in China, the walking race not only carries the task of vying for gold for the country in international large-scale events such as the Olympic Games and the World Championships, but also bears the responsibility to strengthen the people's physique and drive the people's enthusiasm for sports. It also reflects to a certain extent the important symbol of the development of a sports power into a sports power. Walking race is a technology-oriented endurance event. On the basis of good endurance, it is also subject to many rules and technical constraints, which also makes it difficult for athletes to obtain good results. With the development of competitive sports, men’s 20km race walking is very fierce nowadays. The rise of Japan can be said to pose a direct threat to our men’s 20km race walking. We can see that Japan’s grasp of the key technologies of walking race is very in place, focusing on technology Details play a key role in improving athletic performance. In this paper, a comparative study of Kaihua Wang and Toshikazu Yamanishi, men of 20 kilometers from the Asian Games in Jakarta, is conducted by means of literature data analysis, image analysis, mathematical statistics and comparative analysis. The research shows that Kaihua Wang has a relatively large stride when walking at high and low speeds, but Kaihua Wang has uneven steps on the left and right. Although Kaihua Wang has a greater distance between the back pedal and the forward swing than Shanxi, he has an uneven force on the left and right legs. It is stronger than Shanxi Lihe and balance ability; when swinging at high and low speeds, the amplitude of upper limb swing is small, and the left and right are not balanced; Toshikazu Yamanishi and Hou Yi phenomenon are larger than Kaihua Wang, and when landing, Kaihua Wang has a small landing angle on the left and a large undulation distance on the head when supporting on the left.

Influence of multiple sclerosis on dynamic gait stability

Falls are a serious health threat for people with multiple sclerosis (MS). Dynamic gait stability has been identified as a key risk factor of falls. The development of effective interventions for preventing falls requires a sound understanding of how MS affects dynamic gait stability. The purpose of the study was to compare dynamic gait stability within the framework of Feasible Stability Region between people with and without MS during level walking at a self-selected speed. Twenty adults with MS and 25 age- and sex-matched healthy individuals were recruited. Dynamic gait stability at touchdown and liftoff on both the strong and weak sides was assessed as the primary outcome measurement. Spatiotemporal gait parameters, including step times, step length, step frequency, and foot landing angle, were determined as explanatory variables. People with MS exhibited lower stability at both gait events bilaterally than their healthy counterparts. The lower stability was mainly attributable to the slower gait speed in MS than in the healthy control. To compensate for the dynamic gait stability deficit resulting from the slow gait speed, individuals with MS adopted a short step length to shift the center of mass motion state closer to the feasible stability region. For people with MS, the stability value was higher on the weak side than on the strong side at touchdown, but not liftoff. The findings from this study could provide insight into the impact of MS on the control of dynamic gait stability.

Experimental Study of Ground Effect on Horizontal Tail Effectiveness of a Conceptual Advanced Jet Trainer

AbstractThis research has provided the results for a static test of a conceptual advanced jet trainer (CAJT) aircraft in a low-speed wind tunnel within take-off and landing angle of attack limits. ...

Change in fishing performance of tubular pot for conger eels according to the angle of inclination to seabed

An experiment was conducted to investigate the fishing performance of tubular pots for conger eel in South Korea according to the inclination angle on the seabed. The experiment was conducted in a water tank by setting the angle of the tubular pot at 0°, 15°, 30°, 45° and 60° with respect to the bottom level. When the landing angle of the pot was relatively low, conger eels searched for the bait and focused on where the bait smell was being released. Subsequently, conger eels entered the pot. Thus, for catching conger eels, it is advantageous for the bait to be placed at the entrance side while installing the pot. The highest fishing performance in terms of catch per unit effort (CPUE) was at an inclination angle of 15°. There was a significant difference between the CPUEs and the landing angle (Kruskal-Wallis test, p = 0.009). The results of this study could be used to improve the efficiency of tubular pot operations for conger eels.

Adaptation to repeated gait-slip perturbations among individuals with multiple sclerosis

BackgroundPerturbation training, built upon motor adaptation and learning, has been increasingly used as a fall prevention paradigm in older adults. This training paradigm involves repeated externally-induced perturbations (like slips) to facilitate the error-driven learning of necessary motor skills for preventing falls. It remains unknown if people with multiple sclerosis can adapt to large-scale slip perturbations, which impedes the application of perturbation training in persons with multiple sclerosis. This study explored whether people with multiple sclerosis can adapt to large-scale repeated gait-slips. MethodsThirteen individuals with multiple sclerosis (the mean ± standard deviation of the Patient Determined Disability Steps: 2.27 ± 1.42) were exposed unexpectedly to a block of five repeated standard slips while walking on a treadmill. The outcome (fall or recovery) for each slip, as our primary outcome measure, was determined. A battery of secondary variables, including dynamic gait stability and gait parameters, were also calculated. Both primary and secondary variables were compared across trials. ResultsOur participants showed a rapidly reduced slip-fall rate (from 92.3% on the first slip to 30.8% on the fifth, p < 0.001). They mainly adopted proactive, assisted by reactive, strategies to improve dynamic gait stability, thus reducing the risk of slip-falls. The proactive adjustments, including shortened step, reduced foot landing angle, and flexed knee, shifted the center of mass anteriorly to be closer to the base of support. Such changes in center of mass position improved dynamic gait stability before the slip. Dynamic gait stability after the slip was also improved across trials, as a reactive strategy. ConclusionWith practice, people with multiple sclerosis can adapt to large-scale, high-speed, gait-slips and acquire necessary skills against falls. Such skills primarily involve proactive strategy which is assisted by reactive strategy. The proactive strategy would shift the body's center of mass closer to the base of support, improving dynamic gait stability and reducing falls. Our findings could provide a theoretical foundation for deploying perturbation training to prevent falls in people with multiple sclerosis.

Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components.

Although running shoes alter foot-ground reaction forces, particularly during impact, how they do so is incompletely understood. Here, we hypothesized that footwear effects on running ground reaction force-time patterns can be accurately predicted from the motion of two components of the body's mass (mb): the contacting lower-limb (m1 = 0.08mb) and the remainder (m2 = 0.92mb). Simultaneous motion and vertical ground reaction force-time data were acquired at 1,000 Hz from eight uninstructed subjects running on a force-instrumented treadmill at 4.0 and 7.0 m/s under four footwear conditions: barefoot, minimal sole, thin sole, and thick sole. Vertical ground reaction force-time patterns were generated from the two-mass model using body mass and footfall-specific measures of contact time, aerial time, and lower-limb impact deceleration. Model force-time patterns generated using the empirical inputs acquired for each footfall matched the measured patterns closely across the four footwear conditions at both protocol speeds (r2 = 0.96 ± 0.004; root mean squared error = 0.17 ± 0.01 body-weight units; n = 275 total footfalls). Foot landing angles (θF) were inversely related to footwear thickness; more positive or plantar-flexed landing angles coincided with longer-impact durations and force-time patterns lacking distinct rising-edge force peaks. Our results support three conclusions: 1) running ground reaction force-time patterns across footwear conditions can be accurately predicted using our two-mass, two-impulse model, 2) impact forces, regardless of foot strike mechanics, can be accurately quantified from lower-limb motion and a fixed anatomical mass (0.08mb), and 3) runners maintain similar loading rates (ΔFvertical/Δtime) across footwear conditions by altering foot strike angle to regulate the duration of impact. NEW & NOTEWORTHY Here, we validate a two-mass, two-impulse model of running vertical ground reaction forces across four footwear thickness conditions (barefoot, minimal, thin, thick). Our model allows the impact portion of the impulse to be extracted from measured total ground reaction force-time patterns using motion data from the ankle. The gait adjustments observed across footwear conditions revealed that runners maintained similar loading rates across footwear conditions by altering foot strike angles to regulate the duration of impact.

A Mathematical Model of Achilles Tendon Overload During Jump Shot.

Introduction:Achilles tendon injuries usually occur with abrupt movements at the level of the ankle and foot, and the consequence is the overload of the Achilles tendon.Aim:Examine the Achilles tendon load as a function of the landing angle, and find the critical point at which the tendon overload begins and when a further increase in the landing angle can lead to rupture.Methods:The study has a prospective character. The input data represent the anthropometric values of the respondents, who are professional basketball players in the senior national team of Bosnia and Herzegovina and were processed in the CATIA v5-6 software solution. Software data processing analyzed the landing angles and the transfer of force to the Achilles tendon. The end result is a regression curve, which projects the angle at which the Achilles tendon is overloaded, and indicates an increased risk of possible injury to the tendon itself.Results:The onset of overloading starts at an angle of 32.28° and at an angle of 35.75° the overloaded load occurs, indicating the need for the subject to change the position of the foot to prevent damage to the tendon itself.Conclusion:An angle of 35.75° is the critical point at which the Achilles tendons are overloaded at the very landing. Prevention of injury should go in the direction of practicing the feet for a particular position at the time of the landing, and in the direction to develop adequate footwear that would mitigate the angle at the landing.

A Modified Access Technique of Impella 5.0 Axillary Artery Insertion

The conventional method for the axillary artery insertion of Impella 5.0 is a nontunneling route of the side-graft. We present an alternative technique in order to facilitate device insertion and to ensure protection from potential wound contamination. The technique consists of exiting the graft separately and away from the main incision with an intact skin and subcutaneous fat between the two sites. By proper isolation of the main wound, the risk of infection can thus be largely mitigated. Furthermore, this technique allows a better landing entry angle of graft insertion; the resulting smoother curve trajectory leads to facile device insertion, while the risk of kinking after resumption of flow is readily avoided. A further possible advantage would be a less likely to produce thrombosis at the anastomosis. Differences of this technique have already been reported for insertions of extracorporeal membrane oxygenation (ECMO), and for aortic dissections and aneurysms. Our experience in 8 cases suggests the applicability of our method to access the axillary artery for Impella 5.0 insertion.

Correlation between Dynamic Balance and Likelihood of Valgus Collapse in the Knee

Objectives: To assess the relationship between dynamic balance and risk of valgus collapse. Methods: An exploratory observational analysis was completed. This study consisted of fifty subjects between the ages of 18 and 35. Each subject performed a standard Star Excursion Balance Test (SEBT), and measurements were recorded in each reach direction to identify dynamic balance performance. The subject wasthen recorded using video motion analysis software performing a Drop-Jump Test (DJT) to record the amount of valgus collapse. A correlational measure was then completed to test for associationbetween the two variables.Results: Through analysis with a correlation matrix in SPSS it was found that there was no significant correlation (p ≥ .05) between a subjects score on SEBT and their amount of valgus collapse on the drop jump test. Conclusion: No significant correlation was found between dynamic balance scores and valgus alignment during dynamic movement in young adults. In measuring a subject’s level of valgus collapse using the DJT and correlating with their level of dynamic balance using the SEBT, no relationship was found between having poor dynamic balance and having valgus collapse. There was also no found relationship between having good dynamic balance and a lack of valgus collapse. In light of these results, other musculoskeletal deficits such as trunk landing angle; knee, hip and ankle range of motion deficits; motor control deficits; hip, knee and ankle strength deficits; the level of sports participation; previous coaching; Body Mass Index (BMI); and lack of core control may contribute individually or in combination to dynamic knee position during landing. Further investigation of these variables is warranted.

An evaluation method of supercritical CO2 thickening result for particle transporting

This paper aims to propose an evaluation method for measuring the supercritical CO2 thickening result for particle transporting. By analyzing the particle transporting trajectory in supercritical CO2, the cotangent of particle landing angle (ratio of particle horizontal velocity to vertical velocity) was proposed as a new criterion of thickening result. Previous studies of supercritical CO2 thickening were evaluated and drawn in three dimensions using this new criterion. Moreover, the effects of CO2 density and viscosity on particle vertical and horizontal velocities and the cotangent of particle landing angle were analyzed. The cotangent of particle landing angle is more sensitive to supercritical CO2 density than viscosity. Therefore, supercritical CO2 density should be considered for the evaluation of supercritical CO2 thickening for particle transporting. The particle settling velocity was found to determine the particle transporting distance and also the transporting capability of supercritical CO2. According to this conclusion, the apparatus for experimental evaluation of supercritical CO2 thickening will be miniaturized significantly by the simplification from two-dimensional velocities measurement into one direction, particle settling velocity in vertical direction. Additionally, the supercritical CO2 viscosity was found to have an optimum value, exceeding which the effect of viscosity on particle transporting levels off.

Kinetics Analysis during Stance Phase of Fore Foot Contact versus Rear Foot Contact in Running

The purpose of this study was to compare and analyze the difference of the ankle joint movements during landing. Seven adult males voluntarily participated in the study and the average foot size of the subjects was 269.8 mm. Image analysis equipment and the ground reaction force plate (landing type) was used to measure th kinetic variables. As a result of this study, it was confirmed that the vertical ground reaction force peak point appeared once in the barefoot with forefoot, while two peak points appeared in the barefoot and functional shoe foot with rear foot landing. About ankle angle, fore foot landing ankle angle, the average with bare foot landing was -10.302° and the average with functional shoe foot landing was -2.919°. Also about rear foot landing, ankle angle was 11.648° with bare foot landing and 15.994° with functional shoe landing. The fore foot landing, ankle joint force analysis produced 1423.966N with barefoot and 1493.264N with functional shoes. But, the rear foot landing, ankle joint force analysis produced 1680.154N with barefoot and 1657.286N with functional shoes. This study suggest that the angle of ankle depends on the landing type and bare foot running/functionalized shod running, and ankle joint forces also depends on landing type.

Effects of visual deprivation on stability among young and older adults during treadmill walking

The purposes of this study were 1) to investigate the effect of visual deprivation on stability during treadmill walking in older and young adults, and 2) to examine if such an effect differs between age groups. Under the protection of a safety harness, 10 young (23.20±2.44years) and six older adults (67.83±2.48years) participants performed two 90-s walking trials (one with eyes open or EO and the other with eyes closed or EC) at their self-selected treadmill walking speeds determined during EO walking. The step length, step width, foot landing angle, the duration of stance phase, and cadence were calculated from the foot kinematics collected for each participant. The variability (i.e., the standard deviation) of step length, step width, foot landing angle, and the duration of stance phase was also calculated to quantify the stability during walking. Our results revealed that both young and older adults took a cautious gait pattern during EC walking, as evidenced by the shorter step length, smaller foot landing angle and shortened stance phase compared to EO walking. Under both visual conditions, older adults exhibited shorter step length and smaller foot landing angle than their young counterparts. No age-related differences were observed for the measurements of variability (i.e., the quantification of stability) while the variability measurement of all four variables was higher during EC walking than during EO walking for both age groups. Findings from this study could provide insights into the mechanisms of how visual information affects stability during gait.

A modelling approach to the dynamics of gait initiation.

Gait initiation is an integral and complex part of human locomotion. In this paper, we present a novel compliant-leg model-based approach to understanding the key phases of initiation, the nature of the effective forces involved in initiation, and the importance of the anticipatory postural adjustments (APAs). The results demonstrate that in the presence of APAs, we observe a change in the characteristic of forcing required for initiation, and the energetic cost of gait initiation is also reduced by approximately 58%. APAs also result in biologically relevant leg landing angles and trajectories of motion. Furthermore, we find that a sublinear functional relationship with the velocity error from steady state predicts the required force, consistent with an open loop control law basis for gait initiation.

Effect of Insert Groove Geometry on Chip Breaking Performance

AbstractThe insert groove geometry is an important part of turning tool design. In this article, a systematic design approach is presented for the chip breaker design in turning. The chip breaking ability of various groove geometry of a turning insert is investigated. The ratio of chip thickness to chip curl radius is taken as the index of chip breaking performance. Taguchi method is applied to analyze the contribution to chip breaking performance of each geometric parameter. Response surface methodology is then used to construct a predictive model evaluating the effect of turning conditions and groove geometry on chip breaking performance. The result of this study shows that the feed rate significantly affects chip breaking performance, and that insert with larger land angle, higher back wall and smaller groove is more effective in chip breaking. Among the parameters of the insert groove, the width of the groove has the greatest contribution to chip breaking than the others. The simulation results and predictions are validated by turning experiments.

Optimal guidance law design for guided munitions based on segmental linear functions

To meet the requirements of the landing angle, miss distance, and control energy consumption, we study the optimal guidance law design for time-varying systems. In general, however, the optimal guidance law cannot be solved analytically. To solve the problem, we present a design method that combines the optimal control theory and segmental linear functions (SLFs). The optimal guidance law is designed using the proposed method. Ballistic simulations are conducted. Compared with the proportional navigation law, the optimal guidance law significantly increases the landing angle and decreases the miss distance. By averaging the time-varying coefficients of the optimal guidance law, we obtain a suboptimal guidance law. Simulations using the suboptimal guidance law are also made, and the results are compared with those of the optimal guidance law. The suboptimal guidance law is extremely simple and requires minimal onboard computational resources.

Effect of Flexible Back on Energy Absorption during Landing in Cats: A Biomechanical Investigation

Cats are characterized by their excellent landing ability. During the landing, they extend and bend their flexible backs. This study was undertaken to examine the effect of flexible back on impact attenuation. We collected kinematic and ground reaction force data from cats performing self-initiated jump down at different heights. Based on these measurements, the mechanical energy and elastic back energy were calculated. Further, we derived a beam model to predict back stiffness from the morphology of the vertebral spines. We found that cat could actively modulate the bending level of flexible back and the landing angle at different heights, making some kinetic energy be stored briefly as elastic strain energy in the back. This mechanism allows cat to reduce the kinetic energy dissipated by limbs and improve the efficiency of energy absorption. These results can provide biological inspiration for the design of a flexible spine on a landing robot, and we anticipated their use in the energy absorption equipments for planetary exploration.

Research Progress of Coal Villages in China Based on Literatures Analysis

Using China National Knowledge Infrastructure as the retrieve source, research papers of villages overlapping coal resources in recent 48 years are analyzed from the aspects of time distribution, periodical distribution, topic distribution etc. Then the content of research literature is analyzed qualitatively and the research progress is revealed. The results show that: The total amount of literature is less, the gross number is only 331; Besides core journals, the ordinary journals occupies the large proportion among the journals on which the research papers published; It can generally be divided into two research themes, that is coal mining technology under villages and relocation of village overlapping coal resources. Compared with the first, the study of village relocation is weak, and much more study is in a shallow level; The research subject is single, and the technical personnel and workers at the basic level of coal enterprises occupy a large proportion. Although the village relocation involves a lot of land issues, the research of land scholars on this field is not much. To strengthen and broaden the research of relocation of villages overlapping coal resources is the trend of future research in this field. Comprehensive and quantitative research from the land, management, ecology, environment and other multi angle, multi domain, multi discipline should be conducted.

Exploration and Comparison of the Pre-impact Lead Time of Active and Passive Falls Based on Inertial Sensors

Research on falls in elderly people has a great social significance because of the rapidly growing of the aging population. The pre-impact lead time of fall (PLT) is an important part of the human fall theory. PLT is the longest time for a person who is going to fall to take action in order to prevent the fall or to reduce bodily injuries from the fall impact. However, there is no clear definition of PLT so far. There is also no comparative study for active and passive falls. In this study, we proposed a theoretical definition of the PLT, based on a new method of fall event division. We also compared the differences of PLT and the related angles between active and passive falls. Eight healthy adult subjects were arranged to perform three kinds of activities of daily living (sitting, walking and lying), and two kinds fall activities (active and passive) in three directions (forward, backward and lateral fall). Nine inertial sensor modules were used to measure the body segmental kinematic characteristics of each subject in our experimental activities. In this paper, a fall event was suggested to divide into three or four phases and then the critical phase could be divided into three periods (pre-impact, impact, and post-impact). Two fall models were developed for active and passive falls using acceleration data. The average value of PLT for active falls is about 514 ± 112 ms and it is smaller than the value for passive falls, which is 731 ± 104 ms. The longest PLTs were measured on the chest or waist instead of other locations, such as the thigh and shank. The PLTs of the three kinds of fall activities were slightly different, but there was a significant difference between two fall modes. The PLT showed the correlation to the body angle at the start of PLT, but it was uncorrelated at the end of PLT. The angles at the start of PLT had slight variations (<10 degrees) from the steady standing state except in passive forward falls (max 16 degrees) due to the self-control. The landing angles were significantly different in the both fall modes in all the three directions of fall, indicating the state of the trunk was uncertain when the hip contacted the ground. It can be concluded that it is feasible to prevent falls by using an early pre-impact fall alarm device; the present study provides important reference for development of pre-impact fall alarm devices.

Finite Element Analysis of Pedestrian-Bridge Dynamic Interaction

The pedestrian-bridge dynamic interaction problem in the vertical direction based on a bipedal walking model and damped compliant legs is presented in this work. The classical finite element method, combined with a moving finite element, represents the motion of the pedestrian in the dynamic analysis of a footbridge. A control force is provided by the pedestrian to compensate for the energy loss due to the system damping in walking and to regulate the walking performance of the pedestrian. The effects of leg stiffness, the landing angle of attack, the damping ratio of the leg and the mass ratio of the human and structure are investigated in the numerical studies. Simulation results show that the dynamic interaction will increase with a larger vibration level of the structure. More external energy must be input to maintain steady walking and uniform dynamic behavior of the pedestrian in the process. The simple bipedal walking model could well describe the human-structure dynamic interaction.

Biomechanical Study on Take-Off Technique of Junior Male Long Jumpers

The take-off is the most difficult key technique stage of long jump. The related specifications of take-off directly affect long jumper performance. In this paper, biomechanics study method was used to analyse the factors of take-off such as the last two steps step length and pace, the landing angle, the pedal angle, the take-off sector-shaped angle, the jumping initial velocity and the jumping angle, etc, and the main influencing factors of take-off were decided, to seize these factors in the training will contribute to long jump level improvement.