Haiyun Luo

First Affiliated Hospital of Guangzhou Medical University

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Xinxin Wang

Tsinghua University

Xiaobing Zou

Tsinghua University

Songwu Lu

University of California, Los Angeles

Liyang Zhang

Tsinghua University

Yangyang Fu

Tsinghua University

Lixia Zhang

UCLA Health

Xinlei Zhu

Tsinghua University

Yuntao Guo

Tsinghua University

Shen Zhao

Sun Yat-sen University

Ran Zhang

Liaoning Technical University

Cooperative Institutions

Tsinghua University

104

Chinese Academy of Sciences

Guangzhou Medical University

University of Illinois Urbana-Champaign

State Key Laboratory of Respiratory Disease

First Affiliated Hospital of Guangzhou Medical University

Shanghai Jiao Tong University

Peking University

Central South University

University of Hong Kong

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Influences of alloying composition and cooling rate on precipitation behaviors of primary Al₃Zr-D0₂₃ intermetallics in Al-Mg-Li-Zr alloys

Journal of Physics Conference Series (2023)

Tao Liu Huixue Jiang Bin Wang Huabiao Chen Daoxiang Wu

Abstract In the industrial process, the potential benefit of Al 3 Zr precipitates is usually weakened because coarse Al 3 Zr precipitates have no positive effect on the dynamic recovery, recrystallization and grain growth. Effects of alloying composition and cooling rate on precipitation and growth behaviors of primary Al 3 Zr-D0 23 intermetallics were investigated, especially in a large compositional space. Four types of elements exist in the Al 3 Zr-D0 23 phase. Increasing initial Mg, Li, Zr, and Ti contents is beneficial to increase the start precipitation temperature of Al 3 Zr-D0 23 particles. Increasing initial Mg, Li, Zr, Ti contents and reducing cooling rate are beneficial to increase the mean length, decrease the nucleation rate and the number density of Al 3 Zr-D0 23 precipitates. Furthermore, Zr and Ti element contents show a strong positive correlation with the start precipitation temperature and the final length of Al 3 Zr-D0 23 precipitates. Reducing slightly initial Ti content is beneficial to reduce the final length of Al 3 Zr-D0 23 precipitates. Furthermore, two empirical equations were obtained using the multiple linear regression method, which reveal the complex interactions rather than single-element effect of Mg, Li, Zr, and Ti.

Recrystallization (geology)

10.1088/1742-6596/2635/1/012021

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Intersection of Paschen's curves for argon

Physics of Plasmas (2016)

Yangyang Fu Shuo Yang Xiaobing Zou Haiyun Luo Xinxin Wang

The intersection of Paschen's curves for argon with a same gap length but a different electrode radius was observed. While the breakdown voltage increases with the increase of the nonuniformity in the electric field of the gap at lower pressures, it decreases at higher pressures. The reason for the intersection of Paschen's curves was given based on the mean free path length of the electrons inversely proportional to the gas pressure and the electron impact ionization coefficient exponentially increasing with the electric field. The intersection of the Paschen's curves was qualitatively reproduced by a numerical simulation.

10.1063/1.4962673

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Experiments on a table-top X-pinch

Ran Zhang Xinlei Zhu Shen Zhao Haiyun Luo Xiaobing Zou

X-pinch plasma is produced with a high and pulsed current flowing through two or more fine wires that cross and touch at a single point, forming an "X"-shaped structure. A subnanosecond pulsed x-ray point source is usually formed at the crossing point of the wires. X-pinches have been used as x-ray sources for backlighting of high density plasmas such as wire-array Z-pinch plasma and for phase-contrast imaging of soft biological objects that could not be imaged by the conventional x-ray radiography. For the purpose of the clinical or biological application of X-pinch as x-ray source, a table-top X-pinch device was constructed based on a compact (2m×1m×1.5m) pulsed current generator (~ 100 kA,60ns). The whole device was put on a platform under which there are four wheels and thus it can be easily moved by a single person. The current flowing through the X-pinch load was measured with a Rogowski coil and it was almost unchanged for X-pinches made using different wires (5μm, 8μm, 10μm and 13μm Wu wire, 13μm and 25μm Mo wire), which means that the contribution of the wires to the total impedance of the X-pinch load is very small. The characteristics of the x-ray emission from the X-pinch were investigated. The time-resolved x-ray emission was measured with photoconducting detectors (PCDs) and the pattern of the x-ray source was recorded with a pinhole camera. When the above mentioned wires were used as two-wire X-pinches, X-ray pulses from the X-pinches were always observed. As the mass of the two wires increases, the time delay of the x-ray emission relative to the beginning of the current increases. The X-ray pulse consists of single peak or two overlapping peaks of subnanosecond pulsewidth. Two X-ray pulses with a time interval on the order of 10 ns were often observed for an X-pinch of a relatively small mass when the current is high enough. The appearance of the second X-ray pulse is attributed to the second pinch of the plasma. The total energy of the x-ray emission, obtained by the integration of the x-ray pulse over time, changes significantly from shot to shot and is in the range of 0.1J ~ 1J for x-rays of hν >; 1.5 keV. The x-ray spectrum was obtained with PCDs covered with different filters and the major part of the x-rays is with hν <; 2.5 keV. The x-ray source is usually one point or two partly overlapping points, which is consistent with the measurement of x-ray pulse. The x-ray point source has a size ranging from 5 μm to 50 μm. The experimental results show that the table-top X-pinch is suitable to be used as x-ray source for phase-contrast imaging of soft biological objects.

Table (database)

10.1109/plasma.2012.6383637

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SELECT: Self-Learning Collision Avoidance for Wireless Networks

IEEE Transactions on Mobile Computing (2008)

Chun-Cheng Chen Eunsoo Seo Hwangnam Kim Haiyun Luo

The limited number of orthogonal channels and autonomous installations of hot spots and home wireless networks often leave neighboring 802.11 basic service sets (BSSs) operating on the same or overlapping channels, therefore interfering with each other. However, the 802.11 medium access control (MAC) does not work well in resolving inter-BSS interference due to the well-known hidden/exposed-receiver problem, which has been haunting the research community for more than a decade. In this paper, we propose SELECT, an effective and efficient self-learning collision avoidance strategy to address the hidden/exposed-receiver problem in 802.11 wireless networks. SELECT is based on the observation that carrier sense with received signal strength (RSS) measurements at the sender and the receiver can be strongly correlated. A SELECT-enabled sender exploits such correlation using an automated online learning algorithm and makes an informed judgment of the channel availability at the intended receiver. SELECT achieves collision avoidance at packet-level time granularity, involves zero communication overhead, and easily integrates with the 802.11 distributed coordination function (DCF). Our evaluation in analysis, simulations, and prototype experiments show that SELECT addresses the hidden/exposed-receiver problem well. In typical hidden/exposed-receiver scenarios, SELECT improves the throughput by up to 140 percent and the channel access success ratio by up to 302 percent while almost completely eliminating contention-induced data packet drops.

Hidden node problem

Distributed coordination function

10.1109/tmc.2007.70723

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Citations (20)

Zero-configuration indoor localization over IEEE 802.11 wireless infrastructure

Wireless Networks (2008)

Hyuk Lim Lu-Chuan Kung Jennifer C. Hou Haiyun Luo

RSS

10.1007/s11276-008-0140-3

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Citations (138)

Study on flexible surface dielectric barrier discharge plasma film for in situ inactivation of bacteria and viruses

Applied Physics Letters (2022)

Yuntao Guo Mengqi Fang Liyang Zhang Jingjun Sun Xinxin Wang

COVID-19 is still pandemic in the world although it has lasted for more than two years, in situ real-time disinfection of curved surfaces in public places is extremely urgent. A flexible plasma film based on surface dielectric barrier discharge is proposed in this study. In situ disinfection effect and the influence of curvature on the performance are studied. The results showed that the film could in situ inactivate a variety of pathogens. Specifically, 10 min plasma treatment results in a log reduction of 3.10, 3.42, and 3.03 for Escherichia coli, Staphylococcus aureus, and vesicular stomatitis virus, respectively. The discharge power and disinfection effect of the film are independent of the curvature, which proves that it can be used for in situ disinfection of curved surfaces. It is speculated that the combined effects of a strong electric field and radical etching physical damage as well as the chemical damage of reactive oxygen and nitrogen species to the protein are the main reasons for the inactivation of pathogens. The inhibition of the film to Omicron type SARS-CoV-2 pseudovirus is 99.3%, and the killing rate to natural bacteria is 94.3%. The film can run for at least 10 h without significant reduction in disinfection effect. In addition, large-scale and digitalization increase the practical potential of a disinfection film. In conclusion, this film is expected to realize in situ real-time disinfection of curved surfaces such as the buttons of the elevator or instrument and door handles, which is of great significance in blocking the spread of COVID-19.

Water disinfection

10.1063/5.0100114

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Study of Dielectric Barrier Townsend Discharge in 3-mm Air Gap at Atmospheric Pressure

IEEE Transactions on Plasma Science (2014)

Haiyun Luo Kai Liu Junxia Ran Yue Yang Xinxin Wang

Diffuse dielectric barrier discharge was first produced in 3-mm-thick air gap at atmospheric pressure using two plane parallel electrodes each covered by one specific alumina plate with a thickness of 2.3 mm. Based on the discharge photographs of 10 ns exposure time taken with an intensified CCD camera, the diffuse discharge was identified with Townsend discharge. The Townsend breakdown voltage for this 3-mm air gap is about 5.7 kV, significantly lower than 11.2 kV, the streamer breakdown voltage of the air gap. If the alumina plate is too thin, the discharge transits to filamentary discharge. If it is too thick, the discharge is too weak to observe. Thermally stimulated current experiments revealed that there exist more shallow traps in the ceramic than in quartz plate after discharge pretreatment. The uniqueness of the shallow traps in the surface of the specific alumina plate, as well as the effect of the current limitation by dielectric leads to a Townsend discharge.

Townsend discharge

Brush discharge

10.1109/tps.2014.2312543

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Citations (26)

Poster abstract

Fan Ye Haiyun Luo Songwu Lu Lixia Zhang

No abstract available.

10.1145/958491.958545

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Integrated System for On-Site Rapid and Safe Screening of COVID-19

Analytical Chemistry (2022)

Dongheyu Zhang Yuntao Guo Liyang Zhang Yao Wang Siqi Peng

Since the outbreak of coronavirus disease 2019 (COVID-19), the epidemic has been spreading around the world for more than 2 years. Rapid, safe, and on-site detection methods of COVID-19 are in urgent demand for the control of the epidemic. Here, we established an integrated system, which incorporates a machine-learning-based Fourier transform infrared spectroscopy technique for rapid COVID-19 screening and air-plasma-based disinfection modules to prevent potential secondary infections. A partial least-squares discrimination analysis and a convolutional neural network model were built using the collected infrared spectral dataset containing 857 training serum samples. Furthermore, the sensitivity, specificity, and prediction accuracy could all reach over 94% from the results of the field test regarding 968 blind testing samples. Additionally, the disinfection modules achieved an inactivation efficiency of 99.9% for surface and airborne tested bacteria. The proposed system is conducive and promising for point-of-care and on-site COVID-19 screening in the mass population.

Point-of-Care Testing

Coronavirus

Point of care

10.1021/acs.analchem.2c02337

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Ad Hoc Network Security.

Haiyun Luo Hao Yang Lixia Zhang Fan Ye Jiejun Kong

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