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Preparation and characteristic study of Schottky diodes based on Ga_(2)O_(3)thin films

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The Journal of China Universities of Posts and Telecommunications 2024年第2期31卷 28-37页

作者： Zhang Xuhui Chen Haifeng Liu xiangtai Lu Qin Wang Zhan Cheng Hang Che Lujie Guan Youyou Han xiaocong School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

This study uses atomic layer deposition(ALD)to grow Ga_(2)O_(3)films on SiO_(2)substrates and investigates the influence of film thickness and annealing temperature on film *** diode devices are fabricated based on the grown Ga_(2)O_(3)films,and the effects of annealing temperature,electrode size,and electrode spacing on the electrical characteristics of the devices are *** results show that as the film thickness increases,the breakdown voltage of the fabricated devices also increases.A Schottky diode with a thickness of 240 nm can achieve a reverse breakdown voltage of 300 *** film quality significantly improves as the annealing temperature of the film *** a voltage of 5 V,the current of the film annealed at 900℃is 64 times that of the film annealed at 700℃.The optimum annealing temperature for Ohmic contact electrodes is 450℃.At 550℃,the Ohmic contact metal tends to burn,and the performance of the device is *** the electrode spacing increases the forward current of the device but decreases the reverse breakdown *** the Schottky contact electrode size increases the forward current,but the change is not significant,and there is no significant change in the reverse breakdown *** device also performs well at high temperatures,with a reverse breakdown voltage of 220 V at 125℃.

关键词： atomic layer deposition(ALD) Ga_(2)O_(3)film Schottky diode annealing temperature

Numerical investigation on characteristics of interfacial wave of liquid film in gas-liquid two-phase flow using OpenFOAM

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Chinese Journal of Aeronautics 2024年第2期37卷 233-248页

作者： xiaoqi MA Yueshe WANG Jiaming TIAN State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Liquid film cooling as an advanced cooling technology is widely used in space *** operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket *** stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right *** to improve the stability of thin film has become a hot *** view of this,an advanced model based on the conventional Volume of Fluid(VOF)model is adopted to investigate the characteristics of interfacial wave in gas-liquid flow by using OpenFOAM,and the mechanism of formation and development of wave is revealed intuitively through numerical *** effects from gas velocity,surface tension and dynamic viscosity of liquid(three factors)on the wave are studied *** can be found that the gas velocity is critical to the formation and development of wave,and four modes of droplets generation are illustrated in this ***,a gas vortex near the gas-liquid interface can induce formation of wave easily,so changing the gas vortex state can regulate formation and development of ***’s more,the change rules of three factors influencing on the interfacial wave are obtained,and the surface tension has a negative effect on the formation and development of wave only when the surface tension coefficient is above the critical value,whereas the dynamic viscosity has a positive effect in this ***,the maximum height and maximum slope angle of wave will level off as the gas velocity ***,the maximum slope angle of wave is usually no more than 38°,no matter what happens to the three factors.

关键词： Interfacial wave Gas-liquid Two-phase flow VOF model OpenFOAM

Design of digital calibration based on variable step size of sub-binary SAR ADC

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The Journal of China Universities of Posts and Telecommunications 2024年第2期31卷 62-71页

作者： Liu Wei Zhao Yanke Shang Shiguang School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

Addressing the impact of capacitor mismatch on the conversion accuracy of successive approximation register analog-to-digital converter(SAR ADC),a 12-bit 1 MS/s sub-binary SAR ADC designed using variable step size digital calibration was *** least mean square(LMS)calibration algorithm was employed with a ramp signal used as the calibration *** errors,extracted under injected disturbances,underwent iterative training to optimize weight *** address the trade-off between conversion accuracy and speed caused by a fixed step size,a novel variable step size algorithm tailored for SAR ADC calibration was *** core circuit and layout of the SAR ADC were implemented using the Taiwan Semiconductor Manufacturing Company(TSMC)0.35μm complementary metal-oxide-semiconductor(CMOS)commercial *** of the SAR ADC calibration algorithm was conducted using Simulink,demonstrating quick convergence and meeting conversion accuracy requirements compared to fixed step size *** results indicated that the convergence speed of the LMS digital calibration algorithm with variable step size was approximately eight times faster than that with a fixed step size,also yielding a lower mean square error(MSE).After calibration,the simulation results for the SAR ADC exhibited an effective number of bit(ENOB)of 11.79 bit and a signal-to-noise and distortion ratio(SNDR)of 72.72 dB,signifying a notable enhancement in the SAR ADC performance.

关键词： successive approximation register analog-to-digital converter(SAR ADC) variable step size digital calibration disturbance technique

Energy-efficient reconfigurable processor for QC-LDPC via adaptive coding-voltage-frequency tuning

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The Journal of China Universities of Posts and Telecommunications 2024年第2期31卷 72-84页

作者： Chang Libo Hu Yiqing Du Huimin Wang Jihe School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China School of Computer Science Northwestern Polytechnical UniversityXi'an 710072China

To apply a quasi-cyclic low density parity check(QC-LDPC)to different scenarios,a data-stream driven pipelined macro instruction set and a reconfigurable processor architecture are proposed for the typical QC-LDPC *** data-level parallelism is improved by instructions to dynamically configure the multi-core computing ***,an intelligent adjustment strategy based on a programmable wake-up controller(WuC)is designed so that the computing mode,operating voltage,and frequency of the QC-LDPC algorithm can be *** adjustment can improve the computing efficiency of the *** QC-LDPC processors are verified on the xilinx ZCU102 field programmable gate array(FPGA)board and the computing efficiency is *** experimental results indicate that the QC-LDPC processor can support two encoding lengths of three typical QC-LDPC algorithms and 20 adaptive operating modes of operating voltage and *** maximum efficiency can reach up to 12.18 Gbit/(s·W),which is more flexible than existing state-of-the-art processors for QC-LDPC.

关键词： quasi-cyclic low density parity check(QC-LDPC) dynamic voltage and frequency scaling(DVFS) reconfigurable computing coarse-grained reconfigurable arrays(CGRAs)

Performance study of vertical MSM solar-blind photodetectorsbased onβ-Ga_(2)O_(3)thin film

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The Journal of China Universities of Posts and Telecommunications 2024年第2期31卷 17-27页

作者： Chen Haifeng Che Lujie Lu Qin Wang Shaoqing Liu xiangtai Liu Zhanhang Guan Youyou Zhao Xu Cheng Hang Han xiaocong Zhang Xuhui School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

In this work,β-Ga_(2)O_(3)thin films were grown on SiO_(2)substrate by atomic layer deposition(ALD)and annealed in N_(2)atmosphere to enhance the crystallization quality of the thin films,which were verified from X-rays diffraction(XRD).Based on the grownβ-Ga_(2)O_(3)thin films,vertical metal-semiconductor-metal(MSM)interdigital photodetectors(PDs)were fabricated and *** PDs have an ultralow dark current of 1.92 pA,ultra-high photo-to-dark current ratio(PDCR)of 1.7×10^(6),and ultra-high detectivity of 4.25×10^(14)Jones at a bias voltage of 10 V under 254 nm deep ultraviolet(DUV).Compared with the horizontal MSM PDs under the same process,the PDCR and detectivity of the fabricated vertical PDs are increased by 1000 times and 100 times,*** addition,the vertical PDs possess a high responsivity of 34.24 A/W and an external quantum efficiency of 1.67×10^(4)%,and also exhibit robustness and repeatability,which indicate excellent *** the effects of electrode size and external irradiation conditions on the performance of the vertical PDs continued to be investigated.

关键词： Ga_(2)O_(3) atomic layer deposition(ALD) annealing vertical metal-semiconductor-metal(MSM)interdigital photodetectors

Airfoil friction drag reduction based on grid-type and super-dense array plasma actuators

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Plasma Science and Technology 2024年第2期26卷 94-103页

作者：方子淇宗豪华吴云梁华苏志 School of Aerospace Engineering Xi'an Jiaotong UniversityXi'an 710049People's Republic of China School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049People's Republic of China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering UniversityXi'an 710038People's Republic of China

To improve the cruise flight performance of aircraft, two new configurations of plasma actuators(grid-type and super-dense array) were investigated to reduce the turbulent skin friction drag of a low-speed airfoil. The induced jet characteristics of the two actuators in quiescent air were diagnosed with high-speed particle image velocimetry(PIV), and their drag reduction efficiencies were examined under different operating conditions in a wind tunnel. The results showed that the grid-type plasma actuator was capable of producing a wall-normal jet array(peak magnitude: 1.07 m/s) similar to that generated in a micro-blowing technique, while the superdense array plasma actuator created a wavy wall-parallel jet(magnitude: 0.94 m/s) due to the discrete spanwise electrostatic forces. Under a comparable electrical power consumption level,the super-dense array plasma actuator array significantly outperformed the grid-type configuration,reducing the total airfoil friction drag by approximately 22% at a free-stream velocity of 20 m/*** magnitude of drag reduction was proportional to the dimensionless jet velocity ratio(r), and a threshold r = 0.014 existed under which little impact on airfoil drag could be discerned.

关键词： plasma actuator flow control drag reduction airfoil

Reheat effect on the improvement in efficiency of the turbine driven by pulse detonation

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Defence Technology（防务技术） 2024年第1期31卷 200-210页

作者： Junyu Liu Zhiwu Wang Zixu Zhang Junlin Li Weifeng Qin Jingjing Huang School of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China Shenzhen Research Institute of Northwestern Polytechnical university Shenzhen 518057China Mechanical Engineering College Xi’an Shiyou UniversityXi’an 710065China

Due to the strong unsteadiness of pulse detonation,large flow losses are generated when the detonation wave interacts with the turbine blades,resulting in low turbine *** that the flow losses are dissipated into the gas as heat energy,some of them can be recycled during the expansion process in subsequent stages by the reheat effect,which should be helpful to improve the detonationdriven turbine *** this into account,this paper developed a numerical model of the detonation chamber coupled with a two-stage axial turbine,and a stoichiometric hydrogen-air mixture was *** improvement in turbine efficiency attributable to the reheat effect was calculated by comparing the average efficiency of the stages with the efficiency of the two-stage *** research indicated that the first stage was critical in suppressing the flow unsteadiness caused by pulse detonation,which stabilized the intake condition of the second stage and consequently allowed much of the flow losses from the first stage to be recycled,so that the efficiency of the two-stage turbine was *** a 95%confidence level,the efficiency improvement was stable at 4.5%—5.3%,demonstrating that the reheat effect is significant in improving the efficiency of the detonation-driven turbine.

关键词： Pulse detonation turbine engine Hydrogen detonation Turbine efficiency Reheat effect Multi-cycle detonation

Preparation and Swelling Kinetic Analysis of Poly (HPMC-co-AA-co-AM) Super Absorbent Resin

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Journal of Wuhan university of Technology(Materials Science) 2024年第3期39卷 790-799页

作者：马砺 WANG xin LIU xixi WEI Gaoming GUO Ying School of Safety Science and Engineering Xi’an University of Science and TechnologyXi'an 710054China Key Laboratory of Coal Fire Disaster Prevention Xi’an University of Science and TechnologyXi'an 710054China School of Energy Engineering Xi’an Uni-versity of Science and TechnologyXi'an 710054China Yanzhou Coal Mining Co. Ltd.Zoucheng 237500China

Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking ***,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction *** optimized conditions are obtained by the experiment repeating for several *** water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,***,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are *** is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.

关键词： super absorbent resin swelling kinetics water absorption graft copolymerization hydroxypropyl methyl cellulose

Different bactericidal abilities of plasma-activated saline with various reactive species prepared by surface plasma-activated air and plasma jet combinations

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Plasma Science and Technology 2024年第1期26卷 50-61页

作者：贾怡康李甜会张瑞赵鹏瑜王子丰陈旻郭莉刘定新 State Key Laboratory of Electrical Insulation and Power Equipment Center for Plasma BiomedicineXi’an Jiaotong UniversityXi’an 710049People’s Republic of China School of Life Science and Technology Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Plasma-activated water(PAW),as an extended form of cold atmospheric-pressure plasma,greatly expands the application of plasma-based *** biological effects of PAW are closely related to the aqueous reactive species,which can be regulated by the activation *** this study,surface plasma-activated air(SAA)and a He+O_(2)plasma jet(Jet)were parallelly combined(the SAA+Jet combination)or sequentially combined(the SAA→Jet combination and the Jet→SAA combination)to prepare plasma-activated saline(PAS).The PAS activated by the combinations exhibited stronger bactericidal effects than that activated by the SAA or the Jet *** concentrations of H_(2)O_(2)and NO_(2)^(-)were higher in the PAS activated by the Jet→SAA combination,while ONOO^(-)concentrations were close in the three kinds of PAS and^(1)O_(2)concentrations were higher in the PAS activated by the SAA+Jet *** analysis of scavengers also demonstrated that H_(2)O_(2),^(1)O_(2),and ONOO^(-)in the PAS activated by the SAA+Jet combination,and^(1)O_(2)in the PAS activated by the Jet→SAA combination played critical roles in bactericidal ***,the effective placement time of the three PAS varied,and the PAS activated by the Jet→SAA combination could also inactivate 2.6-log_(10)of MRSA cells after placement for more than 60 *** regulation of reactive species in plasma-activated water via different combinations of plasma devices could improve the directional application of plasma-activated water in the biomedical field.

关键词： plasma-activated water surface plasma-activated air plasma jet bactericidal effect reactive species