OPTIMIZATION OF FLIGHT DISTANCE FOR THREE TYPES OF JAVELIN TIP

In this study, optimization of javelin flight distance was carried out using a genetic algorithm. Javelin tips with three different shapes were designed within the confines of the regulations. The first design was that of a typical commercially available tip, whereas the second design was thinner and the third design thicker than the commercially available tip. The aerodynamic forces acting on the three types of javelin tip with respect to the angle of attack were calculated using a commercial solver. In the optimization study, the design variables were the initial conditions at release (determined by the thrower), and the objective function was the flight distance. The flight distance was calculated by numerical integration of the equations of motion. It was found that the flight distance for the thinner design was shorter than that for the other two types. The key to a longer flight distance is that in the first half of the flight the drag should be small (the angle of attack should be small) and in the second half of the flight the lift should be large (the angle of attack should be large)

Aerodynamic drag of modern soccer balls

Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 105 (drag coefficient, Cd ≈ 0.12), ~2.8 × 105 (Cd ≈ 0.13), ~3.3 × 105 (Cd ≈ 0.13), and ~2.4 × 105 (Cd ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces

Factors of unpredictable shots concerning new soccer balls

AbstractThe configuration of new soccer balls has closely approached a perfect round shape by not only reducing the number of panels but also by eliminating roughness of the panel joints by utilizing thermal bonding process recently. Therefore, in a non-rotating or low-rotating moving shot, a soccer ball drops and curves, i.e. motion by the change of wake flow, which is called a knuckle ball effect. Factors of the knuckle ball effect on the new soccer balls were investigated in case of a non-rotating shot and a low-rotating one. A correlation between fluctuation of the wake and fluid forces was identified in a symmetric panel configuration of the ball. The asymmetric configuration of the ball panel was also investigated as a factor to bring unpredictable change of the ball flight path. The low-rotating ball changes its frontal area against the moving direction and it produces irregular lateral forces. Consequently, the factors which produced the knuckle ball effect were found to be different from the case of non-rotating shots and low rotating shots

Ski jumping flight skill analysis based on high-speed video image

AbstractMages of the initial 40 m part of a flight of 120-m ski jumping were recorded by a fixed high-speed video camera in Hakuba Ski Jumping Stadium. The time variations of the forward leaning angle and the ski angle of attack were measured from the video image and the aerodynamic forces were calculated from kinematic data. Some correlations were investigated between the reduced jumping distance Dr, which is an initial speed corrected flight distance, and some key angles and the initial transition time, as well as those between Dr and the aerodynamic force coefficients. Jumping performance is compared between advanced jumpers and beginner jumpers

Optimization of the moment of inertia and the release conditions of a discus

AbstractThis paper describes the concurrent optimization of the design of a discus and the skill with which it is thrown. The objective function for optimization is the flight distance, where longer is better. Thirteen control variables are considered, twelve of which are concerned with the skill of the thrower. These determine the launch conditions, which are controlled by the thrower when he or she throws the discus. The final variable is concerned with the discus itself. This is the moment of inertia on its transverse axis. The optimization was carried out with the aid of a genetic algorithm, and the entire trend for each generation between the objective function and the control variables could be visualized with the aid of self organizing maps. It was found that the flight distance achieved with concurrent optimization was longer than that optimized for skill alone. In the case of the optimal flight, the angle of attack should always be less than the stalling angle

AERODYNAMIC EFFECTS OF A PANEL ORIENTATION IN VOLLEYBALL FLOAT SERVE

The purpose of this study was to clarify the aerodynamic and trajectory characteristics on four type volleyballs using the wind tunnel experiments and a hitting robot. We confirmed, in particular, that the critical Reynolds number (Recr) changed depending on the ball types and panel orientations. Recr for Mizuno ball (conventional) was determined to be ~2.8 × 105 (Drag coefficient; Cd = 0.16) on panel orientation A and ∼2.0 × 105 (Cd = 0.20) on panel orientation B. On the other hand, Recr for Mikasa ball (Olympic Official) was ∼2.9 × 105 (Cd = 0.16) in the panel orientation A and ∼3.3 × 105 (Cd = 0.15) in panel orientation B. Moreover, we found that the landing position of all volleyballs varied depending on the ball type and the orientation of the panel. In particular, Molten ball has a longer flight distance than other balls and its landing point was biased toward the left side. On the other hand, Mikasa ball had a relatively short flight trajectory and its landing point was biased to the right. Therefore, it can be hypothesized that during a float serve, the flight trajectory will change depending on the type of volleyball and their orientation

Vestibule-Middle Ear Dehiscence Tested With Perilymph-Specific Protein Cochlin-Tomoprotein (CTP) Detection Test

An 8-year-old boy was referred to the ENT department for further evaluation of right-sided conductive hearing loss. A small cyst anterior to the oval window and fixation of the stapes footplate were observed during an exploratory tympanotomy. The concentration of a perilymph-specific protein, cochlin-tomoprotein (CTP), in the middle ear lavage fluid was measured with an ELISA-based CTP detection kit. The level of CTP in the middle ear lavage fluid before fenestration of the cyst was 0.26 ng/ml (negative), and its level after fenestration was 2.98 ng/ml (positive), confirming the presence of perilymph in the cyst. A small bone dehiscence, considered to be the fissula ante fenestram, was observed anterior to the stapes footplate after removal of the cyst. The CTP detection test results allowed us to confirm that the small bone dehiscence was connected to the inner ear

Involvement of the accumbal osteopontin-interacting transmembrane protein 168 in methamphetamine-induced place preference and hyperlocomotion in mice

Chronic exposure to methamphetamine causes adaptive changes in brain, which underlie dependence symptoms. We have found that the transmembrane protein 168 (TMEM168) is overexpressed in the nucleus accumbens of mice upon repeated methamphetamine administration. Here, we firstly demonstrate the inhibitory effect of TMEM168 on methamphetamine-induced behavioral changes in mice, and attempt to elucidate the mechanism of this inhibition. We overexpressed TMEM168 in the nucleus accumbens of mice by using an adeno-associated virus vector (NAc-TMEM mice). Methamphetamine-induced hyperlocomotion and conditioned place preference were attenuated in NAc-TMEM mice. Additionally, methamphetamine-induced extracellular dopamine elevation was suppressed in the nucleus accumbens of NAc-TMEM mice. Next, we identified extracellular matrix protein osteopontin as an interacting partner of TMEM168, by conducting immunoprecipitation in cultured COS-7 cells. TMEM168 overexpression in COS-7 cells induced the enhancement of extracellular and intracellular osteopontin. Similarly, osteopontin enhancement was also observed in the nucleus accumbens of NAc-TMEM mice, in in vivo studies. Furthermore, the infusion of osteopontin proteins into the nucleus accumbens of mice was found to inhibit methamphetamine-induced hyperlocomotion and conditioned place preference. Our studies suggest that the TMEM168-regulated osteopontin system is a novel target pathway for the therapy of methamphetamine dependence, via regulating the dopaminergic function in the nucleus accumbens

T2緩和時間を指標とした15％最大筋力時の手関節伸展運動筋の解析

骨格筋緩和時間(T1, T2)を指標としたMRI法は，表面筋電図法，超音波法に加え新しい骨格筋の運動分析法として注目されている．本研究では，物を把持するなど日常生活で重要な手関節伸展運動について検討した．健常人8名を被験者とし，最大等尺性収縮筋力の15％の等張性収縮運動の前後でのT2強調画像とT2の変化，および運動後25分の回復を測定した．測定筋は，短橈側手根伸筋，総指伸筋，小指伸筋，円回内筋，尺側手根伸筋，深指屈筋，浅指屈筋，尺側手根屈筋，橈側手根屈筋，腕橈骨筋とした．運動後T2強調画像から活動筋を弁別した．短橈側手根伸筋，総指伸筋，小指伸筋にT2の延長を認めた（P＜0.01）．その後，緩やかに短縮したが，短橈側手根伸筋と総指伸筋では25分後までT2の延長を認めた．尺側手根伸筋，円回内筋は延長傾向を認めたが，有意ではなかった．主動筋の短橈側手根伸筋に対して，総指伸筋，小指伸筋に協同作用としての活動が確認できた．屈筋群である尺側手根屈筋，橈側手根屈筋，深指屈筋，浅指屈筋，腕橈骨筋は非活動であった．以上より，T2を指標としたMRI法により手関節運動筋の運動解析が可能であることが示された