Effects of cushion box and closed let-down ladder usage on impact damage to corn kernel during handling.

The main purpose of this study was to evaluate the effects of the cushion box and closed let-down ladder usage in minimizing mechanical damage to corn kernels during free fall. Kernels from a single lot of cultivar KSC 705 were evaluated for percentage of breakage using three drop methods (free fall, with cushion box, and with closed let-down ladder) at five different moisture contents (10%, 15%, 20%, 25%, and 30%), and three drop heights (5, 10, and 15 m). The results showed that the drop methods had a significant effect on the breakage sensibility of kernels. Sample kernels dropped without a ladder (free fall) had a significantly higher average percentage breakage of 13.80%. In the use of the cushion box, the average kernel breakage was calculated to be 11.41%, which was decreased by about 17% more than the free fall. Sample kernels dropped with the closed let-down ladder had a lower average breakage of 7.26%, which showed that the closed let-down ladder significantly helped to reduce mechanical damage to corn kernels by about 47% comparing free fall and by about 37% than the use of the cushion box. The amounts of kernel damage increased significantly with increasing drop height and decreasing moisture content, but the use of the cushion box and closed let-down ladder systems somewhat reduced the adverse effect of the above factors. To minimize mechanical damage to kernels as they fall into the bin, a grain let-down ladder should be installed in the bin so that it can receive kernels from the filling spout with minimum damage. Empirical models were developed for the dependency of damage to corn kernels due to the impact caused by free fall on the drop height and moisture content at different drop methods.

A comprehensive exercise program improves foot alignment in people with flexible flat foot: a randomised trial.

QUESTION: In people with flexible flat foot, what is the effect of a comprehensive exercise program on navicular drop height and medial longitudinal arch angle compared with a control regimen of brief active range of motion exercises? DESIGN: Randomised controlled trial with concealed allocation, blinding of assessors and intention-to-treat analysis. PARTICIPANTS: Fifty-two people with flexible flat foot. INTERVENTION: The experimental group undertook 30-minute exercise sessions three times per week for 6 weeks. The exercises involved active dorsiflexion and plantarflexion, foot shortening exercises, gluteal muscle strengthening, and stretching. The control group performed active dorsiflexion and plantarflexion only for 6 weeks. OUTCOME MEASURES: Navicular drop height and longitudinal arch angle. RESULTS: Randomisation allocated 26 participants to each group. One participant from the experimental group and two from the control group did not complete the study. After 6 weeks, the participants in the experimental group improved their navicular drop height by 0.4 cm (95% CI 0.4 to 0.5) more than those in the control group. These participants also improved their longitudinal arch angle by 16 deg (95% CI 13 to 19) more than those in the control group. CONCLUSION: In people with flexible flat foot, a comprehensive 6-week exercise program improved the navicular drop height and longitudinal arch angle more than active dorsiflexion and plantarflexion alone. This improved the cosmetic appearance of the foot and reduced progression towards more severe flat foot, which typically becomes symptomatic. TRIAL REGISTRATION: CTRI/2021/07/034599.

Effects of cushion box and closed let-down ladder usage on damage to corn during handling: physiological deterioration.

BACKGROUND: Corn seeds have a high susceptibility to mechanical damage due to their large size and mass. The main purpose of this study was to evaluate the effects of the cushion box and closed let-down ladder usage in minimizing the negative influence of the free fall on the storage potential of corn seeds. Corn seeds were evaluated for the extent of physiological damage by measuring the seed deterioration by the accelerated aging test (percentage loss in germination in the accelerated aging test), using three drop methods (free fall, with cushion box, and with closed let-down ladder) at three drop heights (5, 10, and 15 m) and five different moisture contents (10, 15, 20 and 25%). RESULTS: The drop methods had a significant effect on the storage potential of corn seeds. Sample seeds dropped without a ladder (free fall) had a significantly higher average physiological quality loss of 13.87% (loss in accelerated aging germination). In the use of the cushion box, the average percentage loss in germination was calculated to be 11.38%, which was decreased by about 18% more than the free fall. Sample seeds dropped with the closed let-down ladder had a lower average percentage loss in the germination of 8.78%, which showed that the closed let-down ladder significantly helped to reduce mechanical damage to corn seeds by about 37% comparing free fall and by about 23% to the use of the cushion box. The amounts of loss in physiological quality of corn seeds increased significantly with increasing drop height and moisture content, but the use of the cushion box and closed let-down ladder systems somewhat reduced the adverse effect of the above factors. Empirical models were developed for the dependency of physiological damage to corn seeds due to the impact caused by free fall, on the drop height and moisture content at different drop methods. CONCLUSIONS: To minimize mechanical damage to seeds as they fall into the bin, a let-down ladder should be installed in the bin so that it can receive seeds from the filling spout with minimum damage.

Developing a heuristic relationship to predict the spinal injury during vertical impact for autonomous vehicle and bio environment.

BACKGROUND AND OBJECTIVE: Recent research and tested data suggested that spinal injuries occur more often in a frontal impact. Most of the published information is focused on the lumbar spinal injury with respect to axial compression force by varying the height of drops. Parametric studies on the lumbar spinal injury are very scanty. Therefore, the present investigation aimed to optimize the effects of drop height, torso weight and seat angle on the characterization of lumbar injury criteria METHODS: A detailed finite element model of a spine with multi-segmented spinal columns is developed and validated with the experimental or cadaveric tests using CORA evaluation. Hence, Dynamic loading studies or weight drop techniques were used to characterize the effect of drop height, seat angle and torso weight of the upper body on the lumbar spinal injury during a frontal impact. Parametric simulations were carried out using response surface methodology (RSM). Test of significance (p < 0.05) on the parameters was carried out using ANOVA. Desirability Function Approach is used to optimize the parameters for better safety design. RESULTS: The result shows that all the factors considered in the experiment are related to the risk of lumbar spinal injury during the frontal impact. All the factors selected, the drop height, torso weight and the seat angle were the most prominent element in determining the lumbar spinal injury. The injury increased with the increase in the posture angle of the seat. Optimal parameters were determined for the better safety of the occupants as seat angle of 105°, drop height 500 mm and torso weight of 25 kg in vehicle design. During vertical impact, posterior undergoes maximum impact in the portions of vertebra and confirmed with the patient case study fracture of vertical drop incident. CONCLUSIONS: This research insight gives an improved understanding of the parametric influence of design alternatives to minimize the risk of lumbar spinal injury in automotive vehicles. The optimal combination of drop height and the seat angle provides futuristic view on autonomous vehicle seat design.

Repeated drop-weight impact tests on self-compacting concrete reinforced with micro-steel fiber.

Steel fiber has become a proven material that can significantly alter the behavior of different types of concrete mixtures from brittle to more ductile ones. Rich literature is currently available on the mechanical properties of steel fiber-reinforced self-compacting concrete. However, the investigation of the impact resistance of this material to drop weight is still required to enrich the knowledge about its behavior under different loading conditions. An experimental work was conducted in this research to evaluate the performance of steel fiber-reinforced self-compacting concrete under repeated impact loading using the repeated blows test recommended by ACI 544-2R. The tests investigated the effect of drop weight and drop height in addition to fiber content. Straight micro-steel fibers were incorporated in three volumetric contents of 0.5, 0.75 and 1.0% and were compared with a similar plain mixture. The test equipment was adjusted to conduct repeated impact loading from different drop-heights and using different drop-weights. The adopted drop-heights were 450, 575 and 700 mm, while the adopted drop-weights were 4.5, 6.0 and 7.5 kg. The combination of the adopted drop-heights and weights composes four loading cases in addition to the standard loading case with a drop-weight and drop-height of 4.5 kg and 450 mm. The inclusion of micro steel fiber was found to significantly increase the impact resistance of self-compacting concrete with percentage developments ranging from 150 to 860% compared to plain samples. The specimens tested under 4.5 kg and 450 mm drop weight and height exhibited the highest percentage improvement in impact resistance among the five loading cases. The results also showed that the impact ductility of fibrous specimens was up to 24% higher than that of plain specimens.

Impact of acute static-stretching on the optimal height in drop jumps / Impacto agudo do alongamento estático sobre a altura ideal de queda no salto em profundidade / Impacto agudo del estiramiento estático sobre la altura óptima de caída en el salto en profundidad

This study analyzed the effect of static stretching on performance during drop jumps. Furthermore, we investigated if a reduction in drop height would compensate the stretching-caused alterations. Ten physically active male subjects performed drop jumps at four different drop heights without static stretching for the optimal drop height determination. After, they performed drop jumps on two drop heights with static stretching previously. The jump height, contact time and reactive strength index were significantly affected by static stretching. However, only the contact time was significantly improved by the reduction in drop height with previous static stretching. Our results suggest that the decrement in performance after static stretching could be partially compensated by a reduction in drop height, which decreases the contact time near a non-stretching jump condition. This can be explained by the lower landing velocity and, possibly, the smaller reduction in the activation of the plantar flexors muscles. In conclusion, the reduction in drop height seems to be interesting after a static stretching session, aiming to expose the athletes to lower impact forces to maintain jump performance.

O presente estudo analisou o efeito do alongamento estático sobre o desempenho no salto em profundidade. Adicionalmente, foi investigada a redução na altura de queda poderia compensar as alterações causadas pelo alongamento prévio. Dez homens fisicamente ativos realizaram o salto em profundidade em quatro alturas de queda diferentes sem alongamento estático prévio, para determinação da altura de queda ideal, em duas alturas com o alongamento prévio. A altura de salto, o tempo de contato e o índice de força reativa foram significativamente afetados pelo alongamento estático. Contudo, apenas o tempo de contato foi significativamente melhorado com a redução na altura de queda do salto após o alongamento. Nossos resultados sugerem que a diminuição no desempenho após o alongamento pode ser parcialmente compensada com uma redução na altura de queda, diminuindo o tempo de contato para valores próximos ao salto sem alongamento prévio. Isso pode ser explicado pelo menor velocidade de aterrissagem e, possivelmente, pela menor redução na ativação dos músculos flexores plantares. Assim, a diminuição na altura de queda parece ser interessante após a realização do alongamento estático, visando submeter os atletas a menores forças de impacto e manter o desempenho do salto.

En este estudio se analizó el efecto del estiramiento estático sobre el rendimiento en saltos en profundidad. Además, se investigó si una reducción de la altura de caída compensaría las alteraciones causadas por el estiramiento previo. Diez hombres físicamente activos realizaron el salto en profundidad en cuatro alturas diferentes de caída sin estiramiento estático, para la determinación de la altura de caída óptima y en dos alturas con el estiramiento estático previo. La altura del salto, el tiempo de contacto y el índice de fuerza reactiva fueron afectados significativamente por el estiramiento estático. Sin embargo, sólo el tiempo de contacto mejoró significativamente por la reducción de la altura de caída del salto, después del estiramiento. Nuestros resultados sugieren quela disminución en el rendimiento después del estiramiento estático, podría ser parcialmente compensada con una reducción en la altura de caída, disminuyendo el tiempo de contacto para valores próximos al del salto sin estiramiento previo. Esto se puede explicar por la menor velocidad de aterrizaje y, posiblemente, por la menor reducción en la activación de los músculos flexores plantares. En conclusión, la reducción de la altura de caída parece ser interesante después de realizar una sesión de estiramientos estáticos, con el objetivo de someter a los atletas a menores fuerzas de impacto y mantener el rendimiento en el salto.

Predicción de la altura óptima de caída en drop jumps usando antropometría y pruebas motoras / Predicting optimum drop height in drop jumps through anthropometry and motor tests

El objetivo de este estudio ha sido predecir la altura optima de caída (AOC) en los ejercicios pliométricos Drop Jump (DJ) a partir de variables cinemáticas y antropométricas, mediante un modelo de regresión múltiple lineal. Participaron en el estudio 13 sujetos, 6 hombres y 7 mujeres de la liga vallecaucana de atletismo. Inicialmente se determinó la altura de vuelo y longitud de los saltos efectuados con las pruebas físicas Countermovement Jumps (CMJ), Abalakov (ABK), salto largo sin/con impulso de brazos, el tiempo en carreras de 30 y 100 m. Se determinó la composición corporal en % y Kg. (músculo, grasa, óseo y residual) por ecuaciones de regresión (Yuhasz, Mateigka, De Rose, etc.) Además, se valoró utilizando la plataforma de contacto la AOC a partir de los índices de fuerza reactiva (RSI), coeficiente de calidad del salto (CQ), capacidad reactiva del músculo (CR) que se determinan usando los tiempos de contacto y vuelo. La información se analizó con estadística descriptiva e inferencial principalmente con análisis de correlación, regresión lineal múltiple y pruebas no paramétricas para el modelo de regresión. En la AOC con utilización de brazos, el salto largo explicó por sí solo un 99,6% de la variabilidad en la AOC. La variable anterior combinada con el tiempo en 100 m. permitió explicar un 99,8% de la variabilidad en la AOC. Al añadir a la ecuación anterior el porcentaje de asa muscular se pudo explicar un 99,9% de la variabilidad en la AOC. Añadiendo a la ecuación el porcentaje graso se explicó 99,9% de la variabilidad en la AOC.

The aim of this study was to find out if it is possible to predict the land optimal height (AOC) of the plyometric jump (DJ) from kinematic and anthropometric variables using a multiple linear regression model. Thirtee subjects, 13, 6 male and 7 female athletics runners and jumpers of Liga Vallecaucana de Atletismo First, the height of the flight y long jump during the performance of the “countermovement jump” (CMJ), Abalakov, long jump with/without arms impulse, time in 30, 100 m were determined. Then, the corporal composition in % and Kg. (muscle, fat, bone and residual tissue), using Yuhasz, Mateigka, and De rose equations. So, with the contact platform calculate the several index: reactive strength index (RSI), quality coefficient (CQ) and muscle reactive output (CR) using flight and contact times. The information was analize with descriptive and inferential statistics meanly correlation, regression linear and non parametric tests for the regression model. In the AOC using arms, long jump explain 99,6% of the variability. the Prediction power was increased to 99,8% including in the model 100 m time. The inclusion of the muscle mass, as a third variable, raised the prediction power to 99,9% of land optimal height variability. Adding to the corporal fat (%) to the model, the prediction power was 99,9% too.