Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The dev...Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The development of rtmning velocity, temperature, crystallinity and theological force is investigated for the take-up velocity over a range of 6 000 - 10 000 m/min. The position of necking point, temperature rise and abrupt increase of crystallinity move closer to the spinneret with the increase of take-up velocity,展开更多
In a recent work, we calculated the magnetic field inside a free electron due to its spin, and found it to be about B = 8.3 × 1013 T. In the present study we calculate the spinning speed of a free electron in the...In a recent work, we calculated the magnetic field inside a free electron due to its spin, and found it to be about B = 8.3 × 1013 T. In the present study we calculate the spinning speed of a free electron in the current loop model. We show that spinning speed is equal to the speed of light. Therefore it is shown that if electron was not spinning the mass of electron would be zero. But since spinning is an unseparable part of an electron, we say that mass of electron is non-zero and is equal to (m = 9.11 × 10−28 g).展开更多
Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of v...Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions, The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.展开更多
A roll-decoupled course correction fuze with canards can improve the hit accuracy of conventional unguided ammunitions. The fuze increases accuracy by reducing the effect of angular and translational motion produced b...A roll-decoupled course correction fuze with canards can improve the hit accuracy of conventional unguided ammunitions. The fuze increases accuracy by reducing the effect of angular and translational motion produced by the cyclical yawing forces applied on the projectile. In order to investigate the influence of yawing forces on angular motion, a theoretical solution of the total yaw angle function with the cyclical yawing forces is deduced utilizing the 7 degrees of freedom(7-DOF) model designed for this calculation. Furthermore, a detailed simulation is carried out to determine the influence rules of yawing force on angular motion. The calculated results illustrate that, when the rotational speed of the forward part is close to the initial turning rate, the total yaw angle increases and the flight range decreases sharply. Moreover, a yawing force at an appropriate frequency is able to correct the gun azimuth and elevation perturbation to some extent.展开更多
Defect free yarn is a great demand for spinner, knitter, and weaver and also other textile personnel because numerous end products from knit apparels to woven fabrics, from towels to sheets and from carpets to industr...Defect free yarn is a great demand for spinner, knitter, and weaver and also other textile personnel because numerous end products from knit apparels to woven fabrics, from towels to sheets and from carpets to industrial fabrics characteristics significantly depend on the physical properties of yarn. The qualities of rotor yarn are really directed by spinning parameters. The aim of this study is to observe the effect of spinning parameters such as rotor diameter and speed on thick, thin places and neps of yarn in rotor spinning process. 0.11 sliver hank of 100% cotton was used to produce 12 Ne yarn. 65% virgin cotton and 35% wastage cotton were mixed together. The positive impact of spinning parameters on yarn properties were accessed by thick places, thin places and neps. Results indicate that the yarn qualities were improved with increasing of rotor speed and rotor diameter. The rotor diameter was settled to 43 mm while rotor speed fluctuated from 35,000 to 45,000 rpm and rotor speed was fixed to 35,000 rpm while rotor diameter across contrasts from 43 mm to 66 mm.展开更多
文摘Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The development of rtmning velocity, temperature, crystallinity and theological force is investigated for the take-up velocity over a range of 6 000 - 10 000 m/min. The position of necking point, temperature rise and abrupt increase of crystallinity move closer to the spinneret with the increase of take-up velocity,
文摘In a recent work, we calculated the magnetic field inside a free electron due to its spin, and found it to be about B = 8.3 × 1013 T. In the present study we calculate the spinning speed of a free electron in the current loop model. We show that spinning speed is equal to the speed of light. Therefore it is shown that if electron was not spinning the mass of electron would be zero. But since spinning is an unseparable part of an electron, we say that mass of electron is non-zero and is equal to (m = 9.11 × 10−28 g).
基金This work was financially supported by the National Natural Science Foundation of China(Nos.20204007,50390090,20490220,10590355)the Doctoral Foundation of National Education Committee of China(No.20030248008)the 863 Project of China(No.2002AA336120).
文摘Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions, The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.
文摘A roll-decoupled course correction fuze with canards can improve the hit accuracy of conventional unguided ammunitions. The fuze increases accuracy by reducing the effect of angular and translational motion produced by the cyclical yawing forces applied on the projectile. In order to investigate the influence of yawing forces on angular motion, a theoretical solution of the total yaw angle function with the cyclical yawing forces is deduced utilizing the 7 degrees of freedom(7-DOF) model designed for this calculation. Furthermore, a detailed simulation is carried out to determine the influence rules of yawing force on angular motion. The calculated results illustrate that, when the rotational speed of the forward part is close to the initial turning rate, the total yaw angle increases and the flight range decreases sharply. Moreover, a yawing force at an appropriate frequency is able to correct the gun azimuth and elevation perturbation to some extent.
文摘Defect free yarn is a great demand for spinner, knitter, and weaver and also other textile personnel because numerous end products from knit apparels to woven fabrics, from towels to sheets and from carpets to industrial fabrics characteristics significantly depend on the physical properties of yarn. The qualities of rotor yarn are really directed by spinning parameters. The aim of this study is to observe the effect of spinning parameters such as rotor diameter and speed on thick, thin places and neps of yarn in rotor spinning process. 0.11 sliver hank of 100% cotton was used to produce 12 Ne yarn. 65% virgin cotton and 35% wastage cotton were mixed together. The positive impact of spinning parameters on yarn properties were accessed by thick places, thin places and neps. Results indicate that the yarn qualities were improved with increasing of rotor speed and rotor diameter. The rotor diameter was settled to 43 mm while rotor speed fluctuated from 35,000 to 45,000 rpm and rotor speed was fixed to 35,000 rpm while rotor diameter across contrasts from 43 mm to 66 mm.
