World Class Elite Breaststrokers Downward Kick EMG Muscle Activity of the Gluteus Maximus, Quadriceps Femoris, Hamstring, Gastrocnemius Medialis, Rectus Abdominal, and Erector Spinae

This study analyzed the difference between using a downward breaststroke kick and a horizontal breaststroke kick in a sample of world class elite swimmers.We compared average muscle activity of the gluteus maximus,quadriceps femoris(vastus medialis and rectus femoris),hamstring/long head of the biceps femoris,gastrocnemius medialis,rectus abdominal,and erector spinae when using the downward breaststroke kick technique.We find that when this sample of swimmers utilized the downward breaststroke kick,max speed and velocity per stroke increased,measured by 12,788 EMG samples,where the results are highly correlated to duration of the aerodynamic buoyant force in breaststroke kick technique.The increases in performance observed from measuring the world class elite swimmers is highly correlated to the duration of the kick aerodynamic buoyant force.Among this sample of elite swimmers,the longer a swimmer demonstrates a buoyant force breaststroke kick,the lower the time in a 100 breaststroke.

Simulation Study on Dynamic Stiffness of Kick-reaction Link Actuator

Under the same aerodynamic load,the load transmitted by the kick-reaction link actuator to the aircraft structure is only 1/5 to 1/3 of that of the point-to-point actuator,which can significantly reduce the weight of the structure,and is widely used in the main flight control surface of large and medium-sized civil airliners.In order to restrain the flutter of aircraft rudder surface,it is necessary to design the servo stiffness of the kick-reaction link actuator in the development stage,so that it can meet the dynamic stiffness requirement within the frequency range.Taking the actuator of a civil airliner as the research object,the dynamic stiffness modeling of elevator actuator is carried out on MATLAB platform,and the dynamic stiffness test is carried out to verify the correctness of dynamic stiffness modeling.The simulation and test results show that the actuator can meet the dynamic stiffness design requirements.

FSFIS问题的基于随机kick的ILS&TS混合算法

提出了一种基于随机kick的迭代局域搜索算法(ILS)求解存储容量受限的流水车间问题(FSFIS)·该算法使用新颖的多对不交叉的交换移动构成kick移动,并采用回溯机制保证搜索在有利的空间内进行·通过应用4种邻域结构,每种情况下产生480组随机数据的试验证明该新型算法是快速有效的近优算法·设计了一种在原有的静态禁忌搜索算法中引入了基于随机kick的迭代局域搜索算法的混和算法,这种混合算法可以充分发挥原有的2种算法的各自优势,使目标函数进一步改进·

基于增强型kick策略的ILS算法求解一类聚类问题

提出一种新型的基于环交换邻域的迭代局部搜索算法(ILS),用于求解一类聚类问题.算法的主要特点是:1)基于环交换的邻域结构:环交换邻域与传统的Sw ap和Insert邻域相比,算法在一次迭代中允许多个点同时移动;2)针对聚类问题提出了增强型的k ick移动策略:根据每组内点的密度分布摄动聚类中心,对给定的解重新聚类.实验结果表明,基于环交换的迭代局部搜索算法对求解该类聚类问题是有效的.

考虑kick效应的汽轮机调节级叶片安全性分析

采用喷嘴配汽的汽轮机调节级,部分进汽不仅对机组的气动性能和效率产生影响,而且还会产生很强的汽流激振力,影响到其自身和整个机组的安全性能。文章首先基于ANSYS CFX,计算了某调节级叶片的全三维气动特性,对调节级非定常气动特性和汽流激振力的变化进行了研究,分析得到了动叶进出不进汽弧段所受到的汽流载荷急剧变化的现象,该现象被称之为调节级的kick效应;然后基于ANSYS的结构动力学模块,考虑kick效应对调节级动叶在考虑气流载荷下的动响应进行了分析;最后,根据动响应计算结果,对调节级的安全性进行了评价。整个研究过程和结论,对于调节级的安全性设计具有重要的工程参考价值和指导意义。

双kicked棘轮模型中粒子香农熵演化的研究

Delta-kicked模型是可以实现棘轮效应的哈密顿型量子模型。在双kicked型棘轮模型中，2个频率不同的闪烁势交替作用于1个具有均匀零动量初态的粒子，在量子共振被激发的条件下，模型中便出现棘轮效应。在不同的量子共振下，粒子香农熵演化出现了不同的规律。研究表明从香农熵演化的角度分析，可以更好地判断量子共振是否被激发。

加勒比海小安德列斯岛弧Kick’emJenny海底火山岩的斜长石成分环带:示踪大洋岛弧岩浆房的演化

我们对采自于加勒比海地区小安德列斯岛弧(Lesser Antilles Arc)Kick’em Jenny(KEJ)海底火山玄武岩中的斜长石斑晶进行了矿物形态和成分分析。利用电子探针(EMPA)和LA-ICP-MS测定了具有环带结构的斜长石斑晶中主量元素的空间分布,同时也利用LA-ICP-MS分析了斜长石中Sr的分布。结果表明,在不同的矿物斑晶中,元素含量均表现出和环带结构相联系的空间分布变化。斜长石斑晶中最主要的结构为韵律环带以及熔蚀结构,所测定的矿物边缘都存在An值从由内向外迅速降低的致密韵律环带,可能反映了快速结晶时的不平衡;而晶体内部的稀疏韵律环带结构是由岩浆填充或对流活动导致的。部分斜长石的熔蚀层An值由内向外升高,反映了高Ca岩浆填充的过程。这说明斜长石斑晶的矿物形态和元素环带可以用来制约俯冲带海底火山岩浆从源区上升到岩浆房再到喷发的复杂过程,包括岩浆演化、熔体多次填充、熔体与结晶矿物之间的反应、以及矿物再熔融等。这对于理解海底火山的喷发以及岛弧岩浆岩的演化有重要意义。

Effect of a specialized injury prevention program on static balance, dynamic balance and kicking accuracy of young soccer players

AIM To study the effect of balance intervention program using the "FIFA 11+" program on static and dynamic balance and kicking accuracy of young soccer players.METHODS Twenty young soccer players were allocated to experimental(n = 10) or control(n = 10) groups. The experimental group performed the "FIFA 11+" program three times a week for six weeks. The control group performed their normal warm-up routine. The primary outcomes were measured pre and post intervention, and assessed kicking accuracy, static balance and dynamic balance.RESULTS No differences were found in kicking accuracy following intervention, for both groups, however, static balance improved significantly among the experimental group with significant interaction with the control group, and with high effect size. In addition, the dynamic balance of the left leg of the experimental group, with medium effect size for interaction between groups.CONCLUSION The large effect size of balance improvement that was observed following six weeks of intervention sessions, implies that soccer trainers and coaches should consider the inclusion of "FIFA 11+" as components of programs aimed at improving balance ability/control in young soccer players, as improvement in balance abilities may prevent injuries.

Evolution of gas kick and overflow in wellbore and formation pressure inversion method under the condition of failure in well shut-in during a blowout

With ongoing development of oil exploration and techniques,there is a significant need for improved well control strategies and formation pressure prediction methods.In this paper,a gas-liquid transient drift flow model was established according to the gas-liquid two-phase flow characteristics during the gas kick.A Roe scheme was used for numerical calculation based on the finite volume method.The changes of bottom-hole pressure,casing pressure,the development law of cross-sectional gas holdup,and gas velocity,along with the vertical well depth,were analyzed through simulation examples.The time-series characteristics of mud pit gain were obtained by adjusting the formation parameter.The complex nonlinear mapping relationship between the formation parameters and the mud pit gain was established.The long short-term memory network(LSTM)of deep learning was used to obtain a formation pressure inversion when the blowout is out of control and the well cannot be shut-in.Experimental data from a well were used to verify the gas-liquid two-phase transient drift flow model based on the finite volume method,demonstrating that this method is reliable,with greatly improved prediction accuracy.This approach provides theoretical support for the early monitoring of gas kick during drilling,and for well-killing design and construction after uncontrolled blowout.

The effect of fatigue and duration knowledge of exercise on kicking performance in soccer players

Purpose:The purpose of this study was to investigate the influence of fatigue upon kicking maximal ball velocity and the target-hitting accuracy of soccer players;and also to examine the effect of the knowledge of the exercise duration upon these 2 parameters.Methods:Twenty-four semi-professional soccer players participated in this study and performed maximal instep kicks before and after the implementation of an exercise protocol,either with or without knowledge of the duration of this protocol.Results:A mixed model of analysis of variance showed that kicking maximal ball velocity was significantly affected(F(5,85)=11.6,p<0.001,η^2=0.39) but only after just 1 circuit of the fatigue protocol and then remained similar.Accuracy did not change during the protocol(F(5,75)=0.23,p=0.76,η^2=0.03) and knowing the duration of exercitation did not affect accuracy and velocity development(F(1,23) ≤1.04,p≥0.32,η~2≤0.06).Conclusion:These findings demonstrated the potential negative effects of fatigue on kicking ball velocity in soccer but not in the kicking accuracy and that the effect of fatigue may not be progressive over time.Knowing or not knowing the duration of exercitation did not affect the results.

Quantum to Classical Transition in a System of Two Coupled Kicked Rotors

We investigate the quantum-classical transition in a system of two coupled kicked rotors. We lind that when the mass of one kicked rotor is much smaller than the other＇s, the influence of the light kicked rotor is still able to make decoherence of the heavy one. This leads to the quantum-classical transition of the heavy kicked rotor. We demonstrate this by two different coupling potentials.

The Straightness Backstroke Kick Makes Fast Speed and Increased Lactate Acid. A Case Study Using 3-Times Olympian

In this study, we assess the effectiveness of utilizing a straight knee kick in the backstroke with regard to the overall time, max speed, and distance per stroke when using a straight knee butterfly technique. We analyzed freestyle kick of knee angles from 7-Olympic medalists, 1970＇s S-shaped pulling pattern stroke was used with a bending knee freestyle kick. The straight knee kick used in butterfly competitions resulted in improvements from 54.74 to 51.00 in Men＇s 100-meter butterfly and fi＇om 23.43 to 23.02 in Men＇s 50-meter butterfly. Using a straight knee kick in backstroke competitions resulted in improvements from 1：01.74 to 1：00.55 in the 100-meter backstroke event. Increases in performance speed, max speed and distance per stroke among three elite level swimmers are highly correlated to duration of the kick resistance, and straight knee kick in backstroke. The straight knee kick also resulted in an increase in lactate acid.

A dynamic managed pressure well-control method for rapid treatment of gas kick in deepwater managed pressure drilling

During deepwater managed pressure drilling(MPD),the gas kick may occur in abnormally high-pressure formations.If the traditional well control method is adopted,the treatment time is long and the advantage of early gas kick detection of MPD is lost.The dynamic managed pressure well-control(MPWC)method can be used to rapidly treat gas kick in deepwater MPD.In this paper,considering the effect of large-variable-diameter annulus and complex wellbore temperature in deepwater drilling,a simplified model of non-isothermal gas-liquid two-phase flow was established for dynamic deepwater MPWC simulation.Using this model,the response characteristics of outlet flow and wellhead backpressure were investigated.The results indicated that the gas fraction,outlet liquid flow rate,pit gain and wellhead backpressure presented complex alternating characteristics when gas moved upwards in the wellbore due to the large-variable-diameter annulus.The outlet liquid flow rate would be lower than the inlet flow rate and the pit gain would decrease before the gas moved to the wellhead.The variation trend of the wellhead backpressure was consistent with that of the pit gain.When the gas-liquid mixture passed through the choke,the expansion or compression of the gas caused part of the choke pressure drop to be supplemented or unloaded,delaying the response rate of the wellhead backpressure.The wellbore temperature,borehole diameter and seawater depth had different effects on outlet flow rate,pit gain and wellhead backpressure.This research could provide a new idea for well control methods in deepwater managed pressure drilling.

A Multiphase Wellbore Flow Model for Sour Gas “Kicks”

This study presents a new multiphase flow model with transient heat transfer and pressure coupling to simulate HTHP(high temperature and high pressure)sour gas“kicks”phenomena.The model is intended to support the estimation of wellbore temperature and pressure when sour gas kicks occur during drilling operation.The model considers sour gas solubility,phase transition and effects of temperature and pressure on the physical parameters of drilling fluid.Experimental data for a large-diameter pipe flow are used to validate the model.The results indicate that with fluid circulation,the annulus temperature with H2S kicks is the highest,followed by CO_(2),and CH_(4) is the lowest.The phase transition point of H2S is closer to wellhead compared with CO_(2),resulting in a faster expansion rate,which is more imperceptible and dangerous.With fluid circulation,the drilling fluid density and plastic viscosity both first decrease and then increase with the increase in the well depth.The bottom hole pressure when H2S kicks is greater than that for CO_(2) with the same amount of sour gas,and the pressure difference gradually increases with the increase of H2S/CO_(2) content.In addition,a parametric sensitivity analysis has been conducted to evaluate qualitatively and rank the influential factors affecting the bottom hole temperature and pressure.

The influence of different exercise intensities on kicking accuracy and velocity in soccer players

Purpose: The aim of this study was to investigate the influence of different exercise intensities induced by a soccer specific protocol on kicking performance in soccer players.Methods: Twelve semi-professional male soccer players participated in this study and performed maximal instep kicks before and after the implementation of an exercise protocol to determine the influence of different intensities upon kicking ball velocity and the target-hitting accuracy.Results: Analysis of variance designs with repeated measures showed that maximal ball velocity was affected only after the most intense circuit(F(6, 66) = 2.3; p = 0.041; η2= 0.18), while accuracy was not affected in the protocol(F(6, 66) = 0.19; p = 0.98; η2= 0.02). Low and moderate intensities did not affect accuracy or kicking ball velocity.Conclusion: These findings suggest that kicking ball velocity is influenced by high-exercise intensities. Low and moderate exercise intensities do not affect the performance of the kick, and intensity does not influence accuracy. Otherwise, it is possible that other mechanisms(not only physiological) may influence players during the exercise.

Chaos and quantum Fisher information in the quantum kicked top

Quantum Fisher information is related to the problem of parameter estimation. Recently, a criterion has been proposed for entanglement in multipartite systems based on quantum Fisher information. This paper studies the behaviours of quantum Fisher information in the quantum kicked top model, whose classical correspondence can be chaotic. It finds that, first, detected by quantum Fisher information, the quantum kicked top is entangled whether the system is in chaotic or in regular case. Secondly, the quantum Fisher information is larger in chaotic case than that in regular case, which means, the system is more sensitive in the chaotic case.

Unpredictable Property of a Kicked Billiard Ball

A simultaneous change in the systemic property of a kicked billiard ball is observed from an entirely smooth and conservative state to a piecewise smooth and quasi-dissipative state when a single controlling parameter has been adjusted. The transition induces a sudden change of a typical conservative stochastic web into a transient web. The iterations on the transient web eventually escape to some elliptic islands. In the meantime, a fat fractal forbidden web, which appears also at the threshold, grows up and cuts away increasingly more parts from the original conservative stochastic web. We numerically show that the initial conditions that generated different attractors are mixed in a random manner and the pattern remains unchanged even when smaller and smaller scales are used for examination, indicating a riddle-like basin structure that practically rules out the possibility of predicting the attractors from a given initial condition.

Dynamic Behavior and Quasi—energy Spectrum of Multiband Superlattice Bloch Electrons in Quantum Kicked Potential

In this paper, we study the dynamic behavior and quasi-energy spectrum of multiband superlattice Bloch electrons in quantum kicked potential. We show analytically and numerically the avoided crossing and band suppression about the quasi-energy spectrum, the dynamic nonlocalization, and the electron oscillation behavior between two bands.

Floquet dynamical quantum phase transitions in transverse XY spin chains under periodic kickings

Floquet dynamical quantum phase transitions(DQPTs),which are nonanalytic phenomena recuring periodically in time-periodic driven quantum many-body systems,have been widely studied in recent years.In this article,the Floquet DQPTs in transverse XY spin chains under the modulation ofδ-function periodic kickings are investigated.We analytically solve the system,and by considering the eigenstate as well as the ground state as the initial state of the Floquet dynamics,we study the corresponding multiple Floquet DQPTs emerged in the micromotion with different kicking moments.The rate function of return amplitude,the Pancharatnam geometric phase and the dynamical topological order parameter are calculated,which consistently verify the emergence of Floquet DQPTs in the system.

The Effects of Breaststroke Kick Electromyography Muscle Activity

This paper evaluates the efficiency of using a downward breaststroke kick in a sample of eight elite swimmers.Using a downward breaststroke kick increases the one stroke velocity and max speed but also increases production of lactate acid.Utilizing the downward breaststroke kick we find the 100-meter and 100-yard breaststroke times decrease from 1:05.10s to 1:01.97s and find the downward breaststroke kick increases muscle activity of the quadriceps,biceps,and calves.The increases in performance were observed from measuring the world class swimmers are highly correlated to duration of the kick aerodynamic buoyant force in breaststroke.