The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount o...The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature re- lationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB2 composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356-xTiB2 （x = 2.5wt% and 5wt%） composites using dif- ferential thermal analysis （DTA）. The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2℃ and 3℃ in liquidus temperatures and a variation of 3℃ and 5℃ in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction（fs） vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB2 particles in the molten metal introduced more nucleation sites and reduced undercooling.展开更多
In this paper we have designed an implemented an integrated framework of QoS for Three Level Mobility Model(TLMM),which has been recently proved to be the optimal mobility management solution for next generation wirel...In this paper we have designed an implemented an integrated framework of QoS for Three Level Mobility Model(TLMM),which has been recently proved to be the optimal mobility management solution for next generation wireless IP-based networks.The QoS solution uses a combination of IntServ and DiffServ models incorporated in TLMM architecture.The paper also proposes an effi cient dynamic handover policy that takes care of false handover.Simulation and analytical results have shown that this infrastructure guarantees eff icient QoS handling and scalability among end users.To provide a comparative understanding of the QoS mechanism and signaling load of TLMM we have used TeleMIP(without QoS support) and MIP as alternative mobility management protocols.展开更多
The influence of discharge voltage on ion collecting surfaces in the form of a metal plate and a mesh grid is investigated in a multi-dipole device.In the experiment,a solid metal plate and a mesh grid are placed alte...The influence of discharge voltage on ion collecting surfaces in the form of a metal plate and a mesh grid is investigated in a multi-dipole device.In the experiment,a solid metal plate and a mesh grid are placed alternately at one end of the multi-dipole device.It is seen that except for high negative bias,the ion space charge layer in front of the grid gets depleted with the increase in discharge voltage whereas it gets thickened in front of the plate.It is also observed that the electron loss at the cusp(anode current)changes accordingly in both the cases.The increase in discharge voltage can enhance the Bohm speed of ions towards the ion collecting surfaces.Further,the negative potential applied to the ion collecting surfaces lowers the bulk plasma potential,which in turn affects the anode current.展开更多
This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia(YSZ)coatings.This article depicts dependence of adhe...This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia(YSZ)coatings.This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature,velocity and size of the splat prior to impact on the metallic substrate.Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times.The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied.Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles.The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates.Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity.The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.展开更多
基金financial support from the Indian Institute of Technology Bhubaneswar under the SEED project grant for fabricating the "cooling slope casting" experimental setupthe support extended by Central Research Facility (CRF), Indian Institute of Technology Kharagpur, toward the facility for conducting DTA experiments
文摘The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature re- lationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB2 composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356-xTiB2 （x = 2.5wt% and 5wt%） composites using dif- ferential thermal analysis （DTA）. The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2℃ and 3℃ in liquidus temperatures and a variation of 3℃ and 5℃ in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction（fs） vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB2 particles in the molten metal introduced more nucleation sites and reduced undercooling.
文摘In this paper we have designed an implemented an integrated framework of QoS for Three Level Mobility Model(TLMM),which has been recently proved to be the optimal mobility management solution for next generation wireless IP-based networks.The QoS solution uses a combination of IntServ and DiffServ models incorporated in TLMM architecture.The paper also proposes an effi cient dynamic handover policy that takes care of false handover.Simulation and analytical results have shown that this infrastructure guarantees eff icient QoS handling and scalability among end users.To provide a comparative understanding of the QoS mechanism and signaling load of TLMM we have used TeleMIP(without QoS support) and MIP as alternative mobility management protocols.
文摘The influence of discharge voltage on ion collecting surfaces in the form of a metal plate and a mesh grid is investigated in a multi-dipole device.In the experiment,a solid metal plate and a mesh grid are placed alternately at one end of the multi-dipole device.It is seen that except for high negative bias,the ion space charge layer in front of the grid gets depleted with the increase in discharge voltage whereas it gets thickened in front of the plate.It is also observed that the electron loss at the cusp(anode current)changes accordingly in both the cases.The increase in discharge voltage can enhance the Bohm speed of ions towards the ion collecting surfaces.Further,the negative potential applied to the ion collecting surfaces lowers the bulk plasma potential,which in turn affects the anode current.
文摘This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia(YSZ)coatings.This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature,velocity and size of the splat prior to impact on the metallic substrate.Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times.The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied.Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles.The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates.Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity.The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.
