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Chinese Physics B 2018年第8期27卷 374-385页

作者： Zhen Yang hui-min song Di Jin min Jia Kang Wang Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi＇ an 710038China

The electrical and thermal characterization of near-surface electrical discharge plasma driven by radio frequency voltage are investigated experimentally in this paper. The influences of operating pressure, electrode distance, and duty cycle on the discharge are studied. When pressure reaches 60 Ton. （1 Torr= 1.33322 x 102 Pa） the transition from diffuse glow mode to constricted mode occurs. With the operating pressure varying from 10 Tort to 60 Torr, the discharge energy calculated from the charge-voltage （Q-V） Lissajous figure decreases rapidly, while it remains unchanged between 60 Torr and 460 Torr. Under certain experimental conditions, there exists an optimized electrode distance （8 mm）. As the duty cycle of applied voltage increases, the voltage-current waveforms and Q-V Lissajous figures show no distinct changes.

关键词： radio frequency discharge charge-voltage Lissajous figure temperature distribution plasma ac-tuation

Microstructure evolution and mechanical properties of brazing joint for ultra-thin-walled Inconel 718 considering grain size effect and brazing temperature

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Chinese Journal of Aeronautics 2024年第2期37卷 541-556页

作者： Rui ZHAO Yueshuai song hui KANG min WAN School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Jiangxi 330000China

The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its *** achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution *** evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension *** findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing *** effects of grain size,such as pinning and splitting,are amplified at higher brazing ***,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture *** fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack ***,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.

关键词： EYWORDS Ultra-thin-walled structure Brazing Inconel 718 Grain size effect Brazing temperature

Thermal and induced flow characteristics of radio frequency surface dielectric barrier discharge plasma actuation at atmospheric pressure

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Chinese Physics B 2017年第1期26卷 320-325页

作者： Wei-long Wang Jun Li hui-min song Di Jin min Jia Yun Wu Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University Xi＇an 710038 China

Thermal and induced flow velocity characteristics of radio frequency（RF） surface dielectric barrier discharge（SDBD）plasma actuation are experimentally investigated in this paper. The spatial and temporal distributions of the dielectric surface temperature are measured with the infrared thermography at atmospheric pressure. In the spanwise direction, the highest dielectric surface temperature is acquired at the center of the high voltage electrode, while it reduces gradually along the chordwise direction. The maximum temperature of the dielectric surface raises rapidly once discharge *** several seconds（typically 100 s）, the temperature reaches equilibrium among the actuator＇s surface, plasma, and surrounding air. The maximum dielectric surface temperature is higher than that powered by an AC power supply in dozens of k Hz. Influences of the duty cycle and the input frequency on the thermal characteristics are analyzed. When the duty cycle increases, the maximum dielectric surface temperature increases linearly. However, the maximum dielectric surface temperature increases nonlinearly when the input frequency varies from 0.47 MHz to 1.61 MHz. The induced flow velocity of the RF SDBD actuator is 0.25 m/s.

关键词： radio frequency discharge temperature distribution induced flow velocity plasma aerodynamic actuation

Aerodynamic actuation characteristics of radio-frequency discharge plasma and control of supersonic flow

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Chinese Physics B 2019年第2期28卷 321-330页

作者： Zhen Yang hui-min song Hong-Yu Wang Shan-Guang Guo min Jia Kang Wang Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University

In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse glow discharge can be observed; under the supersonic inflow, the plasma is blown downstream but remains continuous and ***-resolved schlieren is used for flow field visualization. It is found that RF discharge not only leads to continuous energy deposition on the electrode surface but also induces a compression wave. Under the supersonic inflow condition, a weak oblique shock wave is induced by discharge. Experimental results of the shock wave control indicate that the applied actuation can disperse the bottom structure of the ramp-induced oblique shock wave, which is also observed in the extracted shock wave structure after image processing. More importantly, this control effect can be maintained steadily due to the continuous high-frequency(MHz) discharge. Finally, correlations for schlieren images and numerical simulations are employed to further explore the flow control mechanism. It is observed that the vortex in the boundary layer increases after the application of actuation, meaning that the boundary layer in the downstream of the actuation position is thickened. This is equivalent to covering a layer of low-density smooth wall around the compression corner and on the ramp surface, thereby weakening the compressibility at the compression corner. Our results demonstrate the ability of RF plasma aerodynamic actuation to control the supersonic airflow.

关键词： radio-frequency(RF) discharge plasma surface discharge flow control aerodynamic actuation

Experimental study on energy characteristics and ignition performance of recessed multichannel plasma igniter

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Chinese Physics B 2020年第6期29卷 339-348页

作者： Bang-Huang Cai hui-min song min Jia Yun Wu Wei Cui Sheng-Fang Huang Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi’an 710038China

In the extreme conditions of high altitude,low temperature,low pressure,and high speed,the aircraft engine is prone to flameout and difficult to start secondary ignition,which makes reliable ignition of combustion chamber at high altitude become a worldwide *** solve this problem,a kind of multichannel plasma igniter with round cavity is proposed in this paper,the three-channel and five-channel igniters are compared with the traditional *** discharge energy of the three igniters was compared based on the electric energy test and the thermal energy test,and ignition experiments was conducted in the simulated high-altitude environment of the component combustion *** results show that the recessed multichannel plasma igniter has higher discharge energy than the conventional spark igniter,which can increase the conversion efficiency of electric energy from 26%to 43%,and the conversion efficiency of thermal energy from 25%to 73%.The recessed multichannel plasma igniter can achieve greater spark penetration depth and excitation area,which both increase with the increase of *** the same height,the inlet flow helps to increase the penetration depth of the *** recessed multichannel plasma igniter can widen the lean ignition boundary,and the maximum enrichment percentage of lean ignition boundary can reach 31%.

关键词： high altitude extreme condition recessed multichannel plasma igniter discharge energy lean ignition boundary

Suppression of matrix metalloproteinase-2 via RNA interference inhibits pancreatic carcinoma cell invasiveness and adhesion

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World Journal of Gastroenterology 2009年第9期15卷 1072-1078页

作者： Ying-hui Zhi Mao-min song Pi-Lin Wang Tie Zhang Zi-Yi Yin Department of General Surgery Affiliated Beijing Tiantan Hospital Capital Medical University Beijing 100050 China

AIM:To investigate the inhibitory effects of RNA interference (RNAi) on expression of matrix metalloproteinase-2 (MMP-2) gene and invasiveness and adhesion of human pancreatic cancer cell line,***:RNAi was performed using the vector (pGPU6)-based small interference RNA (siRNA) plasmid gene silence system to specifically knock down MMP-2 expression in pancreatic cancer cell line,BxPC-3. Four groups of different specific target sequence in coding region of MMP-2 and one non-specific sequence were chosen to construct four experimental siRNA plasmids of pGPU6-1,pGPU6-2,pGPU6-3 and pGPU6-4,and one negative control siRNA plasmid of pGPU6 (-). MMP-2 expression was measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Cell proliferation and apoptosis were examined by methyl thiazolyl tetrazolium (MTT) and flow cytometry,respectively. The abilities of adhesion and invasion were detected by cell adhesion assay and cell invasion assay using Transwell ***:The expression of MMP-2 was inhibited and the inhibitory effects of different sequence varied. pGPU6-1 group had the most efficient inhibitory effect,followed by pGPU6-2 and pGPU6-3 *** and adhesion were more significantly reduced in pGPU6-1,pGPU6-2 and pGPU6-3 groups as compared with pGPU6 (-) and blank control groups. However,no difference concerning cell proliferation and apoptosis was observed after transfection between experiment groups and control ***:RNAi against MMP-2 successfully inhibited the mRNA and protein expression of MMP-2 in the pancreatic cancer cell line,BxPC-3,leading to a potent suppression of tumor cell adhesion and invasion without affecting cell proliferation and apoptosis. These findings suggest that the RNAi approach towards MMP-2 may be an effective therapeutic strategy for the clinical management of pancreatic tumor.

关键词： Pancreatic neoplasm Tumor metastasis Matrix metalloproteinase-2 Small interfering RNA Tumor invasiveness

Experimental investigation on electrical characteristics and ignition performance of multichannel plasma igniter

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Chinese Physics B 2018年第3期27卷 327-334页

作者： Sheng-Fang Huang hui-min song Yun Wu min Jia Di Jin Zhi-Bo Zhang Bing-Xuan Lin Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'an 710038China Science and Technology on Plasma Dynamics Laboratory Xi'an Jiaotong UniversityXi'an 710049China

Relighting of jet engines at high altitudes is very difficult because of the high velocity, low pressure, and low tempera- ture of the inlet airflow. Successful ignition needs sufficient ignition energy to generate a spark kernel to induce a so-called critical flame initiation radius. However, at high altitudes with high-speed inlet airflow, the critical flame initiation radius becomes larger; therefore, traditional ignition technologies such as a semiconductor igniter （SI） become infeasible for use in high-altitude relighting of jet engines. In this study, to generate a large spark kernel to achieve successful ignition with high-speed inlet airflow, a new type of multichannel plasma igniter （MCPI） is proposed. Experiments on the electrical char- acteristics of the MCPI and SI were conducted under normal and sub-atmospheric pressures （P = 10-100 kPa）. Ignition experiments for the MCPI and SI with a kerosene/air mixture in a triple-swirler combustor under different velocities of inlet airflow （60-110 m/s）, with a temperature of 473 K at standard atmospheric pressure, were investigated. Results show that the MCPI generates much more arc discharge energy than the SI under a constant pressure; for example, the MCPI generated 6.93% and 16.05 % more arc discharge energy than that of the SI at 30 kPa and 50 kPa, respectively. Compared to the SI, the MCPI generates a larger area and height of plasma heating zone, and induces a much larger initial spark kernel. Furthermore, the lean ignition limit of the MCPI and SI decreases with an increase in the velocity of the inlet airflow, and the maximum velocity of inlet airflow where the SI and MCPI can achieve successful and reliable ignition is 88.7 m/s and 102.2 m/s, respectively. Therefore, the MCPI has the advantage of achieving successful ignition with high-speed inlet airflow and extends the average ignition speed boundary of the kerosene/air mixture by 15.2%.

关键词： multichannel plasma igniter high-speed inlet airflow ignition energy ignition performance

Clinical Efficacy of Super-Selective Renal Artery Embolization for Rupture of Renal Angiomyolipoma

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Clinical oncology and cancer researeh 2011年第3期8卷 163-169页

作者： Xu-hua DUAN Guo-feng ZHOU Gan-sheng FENG Chuan-sheng ZHENG hui-min LIANG song-lin song Department of Interventional Radiology Union Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430022 Hubei Province China

OBJECTIVE To evaluate the efficacy of selective transcatheter arterial embolization （TAE） in renal angiomyolipoma （AML） spontaneous ruptures with hemorrhage. METHODS A retrospective evaluation was carried out in 21 renal AML cases with acute bleeding confirmed by imaging. Selective renal arterial embolization was used to control bleeding. All the cases were detected by renal arteriography had abnormal vascular hyperplasia and enlarged blood vessels. RESULTS Initial renal arteriography for all the patients showed that tortuous, hypervascular, and aneurysm-forming angiogenic components with aneurysm formation occurred in 13 cases （61.9%） and extravasation of the contrast agent was found in 8 cases （38.1%）. Immediate complete obliteration was technically successful in 19 （90.5%） of the 21 patients. To prevent uncontrollable complications, 3 patients received nephron-sparing surgery after hemodynamic status was stabilized with TAE a week later. Two days and 3 days after the embolizations, 2 patients presented with incomplete embolizations and then underwent nephrectomy when they were in a stable condition. There were no significant differences in the plasma creatinine levels before and after the treatment. All the patients were followed up for 6 months to 6 years （median, 45 months）. The largest tumor diameter was reduced from （11.57-±4.28） cm to （9.57±2.28） cm. The tumor had no blood supply and no relapses have occurred. CONCLUSION TAE is a technically feasible and minimally invasive procedure for ruptured renal angiomyolipoma. The aneurysms were a predictor of renal AML spontaneous rupture and detection of such aneurysms by CT may help to determine the timing of embolization. In patients who still need surgical treatment, TAE can make tumor resection easier to perform and reduce blood loss during the operation.

关键词： renal angiomyolipoma hemorrhage artery embolization therapy.

Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

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Chinese Journal of Polymer Science 2024年第8期42卷 1134-1146页

作者： Yan Jia Lei Zhai song Mo Yi Liu Li-Xin Liu Xin-Yu Du min-hui He Lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

The traditional high-temperature preparation process of polyimide can cause many problems and limits the wider application in extreme *** important challenge to be solved urgently is the reduction of imidization *** this work,twelve kinds of polyimide films with different chain rigidity were prepared at low temperature of 200℃,in the absence or presence of imidazole used as the *** molecular rigidity and free volume were theoretically calculated,and relationship between structure and properties were systematically *** results show that imidization reaction under low temperatures is significantly affected by the rigidity of molecula r *** rigid structure of polyimide is not conducive to the low-temperature imidization,but this adverse effect can be eliminated by adding catalyst,resulting the notably increased imidization *** optical and thermal properties can be improved to a certain extent for the chemically catalyzed system,resulting in relatively higher heat resistance and thermal *** the mechanical performance could be determined by com plicating factors,greatly different from polyimide films prepa red by high temperature *** investigate aggregation structures of film s,the effect of chain rigidity and catalyst on the stacking or orientation of molecular chains was further *** wo rk can contribute to the understanding of chemically catalyzed imidization that is rarely reported in the existing research,and will provide guidance for the low-temperature preparation of high-performance polyimides.

关键词： Polyimide Imidization Catalyst Structure and properties Aggregation structures

Noninvasive beam diagnosis based on the TM_(010)mode

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Nuclear Science and Techniques 2024年第7期35卷 115-125页

作者： Chuang-Ye song Wen-hui Huang Department of Engineering Physics Tsinghua University BeijingBeijing100084China of Education Beijing100084China

A resonant cavity based on the TM_(010)mode is an effective tool for noninvasive beam characterization. This technique has the advantages of a high signal-to-noise ratio, compact structure, and is related to multiple parameters compared with other beam monitors. In this study, high-precision measurements of the bunch charge, arrival time, bunch length, and energy parameters based on the TM_(010)mode are discussed. A cavity beam arrival time monitor(BAM) utilizing a phase cavity has been widely used in many facilities. Regarding bunch-length measurements, the influence of the beam energy, beam offset,and longitudinal spectrum on the TM_(010)mode are carefully considered to reduce errors, and the theoretical resolution of two cavities with different frequencies is analyzed. Owing to the dependence of the beam velocity of the beam loss factor, this method can also be used for the detection low beam energy using two cavities with the same frequency but different cavity lengths. A set of three cavities with different lengths and frequencies of 1.902 and 11.424 GHz is presented for measuring the four aforementioned parameters.

关键词： TM_(010)mode Noninvasive diagnosis Beam length Low energy