Preparation and property of submicrometre-crystalline Ba0.67Sr0.33TiO3 powders and ceramics

Hanxing Liu,Jing Xu,Bo He,Yiqiu Li,Minghe Cao,Hua Hao,Zhiyong Yu 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

Submicrometre-particulate pure Ba0.67Sr0.33TiO3 (BST) powders approximately 110 nm in size have been prepared by a solidstate reaction technique. BST ceramics derived from powder calcined at different temperatures were fabricated with various sintering conditions. High-density BST ceramics at all sintering temperatures were obtained at a calcination temperature of 950 oC with the highest 99.6% of the theoretical density. Calcining at 950 oC and sintering at 1300 oC for 2 h , BST ceramic samples with an average grain size about 250 nm were obtained, showing satisfying dielectric properties and ferroelectric properties, with high permittivity εr = 7676, low loss factor tanδ = 0.01 and remanent polarization Pr = 9.2 μC/cm2, coercive electric field Ec = 1.58 kV/cm at room temperature.

Intelligent On-demand Routing Protocol for Ad Hoc Network

Yongfei Ye,Xinghua Sun,Minghe Liu,Jing Mi,Ting Yan,Lihua Ding 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.5

Ad hoc networks play an important role in mobile communications, and the performance of nodes has asignificant impact on the choice of communication links. To ensure efficient and secure data forwarding anddelivery, an intelligent routing protocol (IAODV) based on learning method is constructed. Five attributes ofnode energy, rate, credit value, computing power and transmission distance are taken as the basis ofsegmentation. By learning the selected samples and calculating the information gain of each attribute, thedecision tree of routing node is constructed, and the rules of routing node selection are determined. IAODValgorithm realizes the adaptive evaluation and classification of network nodes, so as to determine the optimaltransmission path from the source node to the destination node. The simulation results verify the feasibility,effectiveness and security of IAODV.

Study on grinding mechanism and machining technology of Si3N4 ceramic spindle

Songhua Li,Chuang Li,Minghe Liu,Yonghua Wang,Chuang Zuo,Hao Zhang,Yifeng Gao 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.6

In order to improve the machining accuracy of the cylindrical surface of silicon nitride ceramic spindle, the machining technologyof the cylindrical surface of ceramic spindle was studied by high-speed universal cylindrical grinder in this experiment. Firstly, the primary and secondary order of the influence of various factors on the surface roughness of ceramic spindleis determined by orthogonal experiment, then the influence law of single grinding parameter on the surface roughness ofceramic spindle is explored by single factor experiment, and the prediction model of the grinding surface roughness value ofceramic spindle is calculated by numerical analysis software, and finally the optimal processing parameters of the cylindricalsurface of ceramic spindle are obtained. The experimental results show that the grinding surface roughness of silicon nitrideceramic spindle first decreases and then increases with the increase of grinding wheel linear speed and workpiece linearspeed, and then increases with the increase of transverse feed speed and axial feed speed. The relative error between the predictedvalue of the prediction model and the actual measured value is less than 5%, which shows that the prediction modelhas a good prediction effect and provides a theoretical basis for actual machining

Receiver-centric Buffer Blocking-aware Multipath Data Distribution in MPTCP-based Heterogeneous Wireless Networks

( Yuanlong Cao ),( Qinghua Liu ),( Yi Zuo ),( Fenfen Ke ),( Hao Wang ),( Minghe Huang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.10

One major concern of applying Multipath TCP (MPTCP) to data delivery in heterogeneous wireless networks is that the utilization of asymmetric paths with diverse networking-related parameters may cause severe packet reordering and receive buffer blocking (RB²LOC). Although many efforts are devoting to addressing MPTCP`s packet reordering problems, their sender-controlled solutions do not consider balancing overhead between an MPTCP sender and receiver, and their fully MPTCP mode cannot make MPTCP achieve a desired performance. This paper proposes a novel receiver-centric buffer blocking-aware data scheduling strategy for MPTCP (dubbed MPTCP-rec) necessitating the following aims: (1) alleviating MPTCP`s packet reordering and RB²LOC problems, (2) improving the MPTCP performance, and (3) balancing load between the MPTCP sender and receiver. Simulation results show that the proposed MPTCP-rec solution outperforms the existing MPTCP solutions in terms of data delivery performance in heterogeneous wireless networks.

Receiver-driven Cooperation-based Concurrent Multipath Transfer over Heterogeneous Wireless Networks

( Yuanlong Cao ),( Qinghua Liu ),( Yi Zuo ),( Minghe Huang ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.7

The advantages of employing SCTP-based Concurrent Multipath Transfer (CMT) have been demonstrated to be very useful for data delivery over multi-homed wireless networks. However, there is still significant ongoing work addressing some remaining limitations and challenges. The most important concern when applying CMT to data delivery is related to handling packet reordering and buffer blocking. Another concern on this topic is that current sender-based CMT solutions seldom consider balancing the overhead and sharing the load between the sender and receiver. This paper proposes a novel Receiver-driven Cooperation-based Concurrent Multipath Transfer solution (CMT-Rev) with the following aims: (i) to balance overhead and share load between the sender and receiver, by moving some functions including congestion and flow control from the sender onto receiver; (ii) to mitigate the data reordering and buffer blocking problems, by using an adaptive receiver-cooperative path aggregation model, (iii) to adaptively transmit packets over multiple paths according to their receiver-inspired sending rate values, by employing a new receiver-aware data distribution scheduler. Simulation results show that CMT-Rev outperforms the existing CMT solutions in terms of data delivery performance.

Synthesis and characterization of Ba(TI1-xZRx)O₃ nanopowders by an aqueous coprecipitation method

Xiangbang Cheng,Zhuo Li,Zhonghua Yao,Yang Liu,Zhiyong Yu,Minghe Cao,Hanxing Liu 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

In this study, single phase Ba(Ti1-xZrx)O3 (0 ≤ × ≤ 0.15) nanopowders have been synthesized successfully by an aqueous coprecipitation method at 85 oC without any further heat treatment. The lattice strain calculated by the Hall-Williamson method indicates that the broadening of the XRD peaks is primarily due to the size of particles not to the lattice strain. The increase of the lattice parameter indicates that Zr ions have entered the lattice and a solid solution was successfully obtained. Furthermore, the particle sizes calculated by the Sherrer formula from the XRD patterns are in agreement with the results of SEM and TEM images. The nanopowders obtained can be used to prepare Ba(Ti1-xZrx)O3 ceramics with a tailored grain size and homogeneous composition, and this is significant to investigate the size effect in Ba(Ti1-xZrx)O3 ceramics and understand the relaxor behavior thoroughly. In this study, single phase Ba(Ti1-xZrx)O3 (0 ≤ × ≤ 0.15) nanopowders have been synthesized successfully by an aqueous coprecipitation method at 85 oC without any further heat treatment. The lattice strain calculated by the Hall-Williamson method indicates that the broadening of the XRD peaks is primarily due to the size of particles not to the lattice strain. The increase of the lattice parameter indicates that Zr ions have entered the lattice and a solid solution was successfully obtained. Furthermore, the particle sizes calculated by the Sherrer formula from the XRD patterns are in agreement with the results of SEM and TEM images. The nanopowders obtained can be used to prepare Ba(Ti1-xZrx)O3 ceramics with a tailored grain size and homogeneous composition, and this is significant to investigate the size effect in Ba(Ti1-xZrx)O3 ceramics and understand the relaxor behavior thoroughly.

Effect of ZnO on the microstructures and piezoelectric properties of K0.5Na0.5NbO3 ceramics

Zhuo Li,Xiangbang Cheng,Zhonghua Yao,Yang Liu,Hanxin Liu,Minghe Cao 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

Lead-free ZnO added K0.5Na0.5NbO3 piezoelectric ceramics have been prepared by a conventional solid state process. The XRD results show that all the K0.5Na0.5NbO3 ceramics with various ZnO contents are single phase with an orthorhombic perovskite structure. The bulk density obtained by the Archimedes method indicates that the addition of ZnO improves the density of K0.5Na0.5NbO3 ceramics under the same sintering conditions. Especially, at a level of 1 mol% ZnO, the sample sintered at 1100 oC for 1h exhibits the highest bulk density (ρ = 4.28 g/㎤) and shows optimal piezoelectric properties, d33 = 135 pC/N and kp = 0.40. Lead-free ZnO added K0.5Na0.5NbO3 piezoelectric ceramics have been prepared by a conventional solid state process. The XRD results show that all the K0.5Na0.5NbO3 ceramics with various ZnO contents are single phase with an orthorhombic perovskite structure. The bulk density obtained by the Archimedes method indicates that the addition of ZnO improves the density of K0.5Na0.5NbO3 ceramics under the same sintering conditions. Especially, at a level of 1 mol% ZnO, the sample sintered at 1100 oC for 1h exhibits the highest bulk density (ρ = 4.28 g/㎤) and shows optimal piezoelectric properties, d33 = 135 pC/N and kp = 0.40.

Effect of SiO2 additives on the microstructure and energy storage density of SrTiO3 ceramics

Guanghui Zhao,Yiqiu Li,Hanxing Liu,Jing Xu,Hua Hao,Minghe Cao,Zhiyong Yu 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

The compositions of (1-x) SrTiO3-x SiO2 were prepared by a solid-state reaction. The crystalline structure, microstructure and energy storage performance were studied for the purpose of a potential application in high energy density capacitors. Fine grains with an average size of about 400 nm were obtained by adding SiO2 to SrTiO3 ceramics, which leads to a great enhancement in the breakdown performance of the samples. For SiO2-added samples, the notable increase in breakdown strength makes an obvious increase in energy storage density. With 15 vol.% addition, the sample exhibited an average breakdown strength of 36.1 kV/mm, and an energy storage density of 1.155 J/cm3.