Effect of Morphology and Age on the Closure Ability of Asian Box Turtles(Cuora)

The ability of box turtles to close their shell as an antipredation adaptation and the potential impact of the anterior and posterior lobes of the plastron on the closing force and closing time remain relatively unexplored.Here,keeled(Cuora mouhotii)and flowerback(C.galbinifrons)box turtles,whose shell cannot and can be completely closed,respectively,were studied.Anterior and posterior closing forces were measured using a force transducer,and the closing time was recorded.The anterior closing force in both turtle species was substantially greater than the posterior closing force,reaching approximately 4-fold in adults.Moreover,the anterior closing time in adults was significantly longer than the posterior closing time.This closing force difference can be attributed to the substantially smaller anterior plastron lobe than the posterior lobe in the two species.Additionally,the anterior and posterior closing forces in both species positively correlated with body weight and showed no relationship with the length of the bridge and hinge.Interspecies comparison showed that the anterior and posterior closing forces were significantly greater(approximately 2–4-fold)in flowerback box turtle than in keeled box turtles,regardless of age,and the closure time was significantly longer in adult flowerback box turtles than in adult keeled box turtles.Although the closing forces in both species showed negative allometry,the increase rate was significantly higher in flowerback box turtle than in keeled box turtle.The closing forces in both species were observed to be approximately 4-fold stronger in adults than in juveniles.No sexual dimorphism concerning the anterior and posterior closing forces was observed in either species.In summary,this is the first study to comparatively evaluate the anterior and posterior closing ability of box turtles,demonstrating that age,weight,plastron shape,and the degree of shell closure are important factors affecting closing ability.

Calculation of vaporization pressure in laser penetration welding of 304 stainless steel

Many research results have revealed that vaporization pressure has important effects on the formation of the keyhole and molten pool during laser welding. In this paper, based on law of conservation of energy, an innovative physical model is found to calculate the vaporization pressure during laser welding. In this model, vaporization pressure can be calculated according to some characteristics of the spatter particle. These features include the size, velocity and displacement. They can be measured through images taken by high-speed camera. The periods of this pressure also measured by counting opening and closing time of the bottom keyholes. At this welding condition, the typical vaporization pressure is about 20 203 Pa and the period is about 6. 9 ms. The average opening time of bottom keyholes is about 4. 3 ms, and the closing time is about 2. 6 ms.

Influence of Dropping scales of E7/6 Comber on Process Performance

The dropping scales is an important parameter for comber noil and combing quality. Because the rocking of the nipper shaft makes the nippers move backward and forward through a series of links, the original position of nipper frame is altered when changing the dropping scales, the other parameters of combing are changed accordingly. In this paper, the timing of opening-closing on nipper, the timing of cylinder’s combing, the timing of detaching-lapping and variation of nip pressure are calculated and their effects on combing are analyzed in different dropping scales on E7/6 comber.