In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a wat...In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion.Effects of various factors on bubble disintegration and dispersion were investigated.These factors were stirring mode,eccentricity and rotation speed,nozzle structure,nozzle immersion depth,and gas flow rate.Gas injection from a nozzle at the end of the impeller shaft and from an immersed lance was studied.Under eccentric stirring,a vortex was formed away from the shaft.Small bubbles were produced in the strong turbulence or high shear stress field near the rotating impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring.Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.展开更多
This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transforma...This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control.展开更多
The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field has been studied. The LHW is launched from a waveg...The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field has been studied. The LHW is launched from a waveguide in the plasma edge, and by Brambilla's grill theory, analytic expressions for the wave electric field in the slab model of an inhomogeneous cold plasma have been derived. It is shown that a strong wave electric field will be generated in the plasma edge by injecting LH wave of the power in MW magnitude, and this electric field will induce a poloidal rotation with a sheared poloidal velocity.展开更多
Shoulder pain is a common musculoskeletal complaint,and rotator cuff(RC)pathologies are one of the main causes.The RC undergoes various tendinopathic and avascular changes during the aging process.Other degenerative c...Shoulder pain is a common musculoskeletal complaint,and rotator cuff(RC)pathologies are one of the main causes.The RC undergoes various tendinopathic and avascular changes during the aging process.Other degenerative changes affecting its healing potential make it an appealing target for biological agents.Platelet-rich plasma(PRP)has demonstrated the potential to deliver a high concentration of several growth factors and anti-inflammatory mediators,and its clinical use is mainly supported by experiments that demonstrated its positive effect on muscle,ligaments,and tendinous cells.This review aimed to specify the role of PRP and its future applications in RC tendinopathies based on the current clinical evidence.Due to the different characteristics and conflicting outcomes,clinicians should use PRP with moderate expectations until more consistent evidence is available.However,it is reasonable to consider PRP in patients with contraindications to corticosteroid injections or those with risk factors for inadequate healing.Its autologous origin makes it a safe treatment,and its characteristics make it a promising option for treating RC tendinopathy,but the efficacy has yet to be established.展开更多
基金Projects (50974035,51074047) supported by the National Natural Science Foundation of ChinaProject (20090407) supported by the Doctoral Fund of Ministry of Education,ChinaProject (200921007) supported by Liaoning Key Science and Technology,China
文摘In gas injection refining processes,wide dispersion of small bubbles in the bath is indispensable for high refining efficiency.Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion.Effects of various factors on bubble disintegration and dispersion were investigated.These factors were stirring mode,eccentricity and rotation speed,nozzle structure,nozzle immersion depth,and gas flow rate.Gas injection from a nozzle at the end of the impeller shaft and from an immersed lance was studied.Under eccentric stirring,a vortex was formed away from the shaft.Small bubbles were produced in the strong turbulence or high shear stress field near the rotating impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring.Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.
基金supported by the National Natural Science Foundation of China under Grant 61603263。
文摘This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control.
基金the Nuclear Science Foundation under Grant! No. H7196c0302.
文摘The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field has been studied. The LHW is launched from a waveguide in the plasma edge, and by Brambilla's grill theory, analytic expressions for the wave electric field in the slab model of an inhomogeneous cold plasma have been derived. It is shown that a strong wave electric field will be generated in the plasma edge by injecting LH wave of the power in MW magnitude, and this electric field will induce a poloidal rotation with a sheared poloidal velocity.
文摘Shoulder pain is a common musculoskeletal complaint,and rotator cuff(RC)pathologies are one of the main causes.The RC undergoes various tendinopathic and avascular changes during the aging process.Other degenerative changes affecting its healing potential make it an appealing target for biological agents.Platelet-rich plasma(PRP)has demonstrated the potential to deliver a high concentration of several growth factors and anti-inflammatory mediators,and its clinical use is mainly supported by experiments that demonstrated its positive effect on muscle,ligaments,and tendinous cells.This review aimed to specify the role of PRP and its future applications in RC tendinopathies based on the current clinical evidence.Due to the different characteristics and conflicting outcomes,clinicians should use PRP with moderate expectations until more consistent evidence is available.However,it is reasonable to consider PRP in patients with contraindications to corticosteroid injections or those with risk factors for inadequate healing.Its autologous origin makes it a safe treatment,and its characteristics make it a promising option for treating RC tendinopathy,but the efficacy has yet to be established.
