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Now showing items 145 - 152 of 152

  • Detection of the Spectra of Multicharged Ions with Time Resolution and the Determination of the Parameters of the Hot Component of the Plasma in the Case of the Magnetic Implosion of Multiwire Arrays

    Anan'ev, S. S.   Dan'ko, S. A.   Kalinin, Yu. G.   Ye, Fan   Qin, Yi   Jiang, Shuqing   Xue, Feibiao   Li, Zhenghong   Yang, Jianlun   Xu, Rongkun  

    The dynamics of the hot component of the plasma of imploding multiwire arrays has been analyzed using the time behavior of the X-ray spectral lines of multicharge ions. The spectra of H- and He-like aluminum ions with nanosecond time resolution have been detected using electron-optical chronography in experiments on the implosion of multiwire arrays by mega-ampere currents. The simultaneous appearance of the resonance lines of H- and He-like ions implies that the hot plasma whose electron temperature is higher than 0.5 keV has existed on the axis before the implosion of the main mass of the liner. The further dynamics of the intensity of the lines is primarily attributed to an increase in the mass of the emitting plasma.
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  • Understanding Smartphone Sensor and App Data for Enhancing the Security of Secret Questions

    Zhao, Peng   Bian, Kaigui   Zhao, Tong   Song, Xintong   Park, Jung-Min Jerry   Li, Xiaoming   Ye, Fan   Yan, Wei  

    Many web applications provide secondary authentication methods, i. e., secret questions (or password recovery questions), to reset the account password when a user's login fails. However, the answers to many such secret questions can be easily guessed by an acquaintance or exposed to a stranger that has access to public online tools (e. g., online social networks); moreover, a user may forget her/his answers long after creating the secret questions. Today's prevalence of smartphones has granted us new opportunities to observe and understand how the personal data collected by smartphone sensors and apps can help create personalized secret questions without violating the users' privacy concerns. In this paper, we present a Secret-Question based Authentication system, called " Secret-QA", that creates a set of secret questions on basic of people's smartphone usage. We develop a prototype on Android smartphones, and evaluate the security of the secret questions by asking the acquaintance/stranger who participates in our user study to guess the answers with and without the help of online tools; meanwhile, we observe the questions' reliability by asking participants to answer their own questions. Our experimental results reveal that the secret questions related to motion sensors, calendar, app installment, and part of legacy app usage history (e.g., phone calls) have the best memorability for users as well as the highest robustness to attacks.
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  • Optical and electrical properties o transparent conductive air-stable C-axis aligned crystalline InGaZnON thin films

    Yao, Jian Ke   Lin, Jia Min   Ye, Fan   Fan, Ping  

    The concentrations of N (C-N) and interstitial metal defects (C-Mi) and the film thickness (d) dependent microstructure and optical and electrical properties of InGaZnON thin films deposited by RF sputtering are studied. The thin films have a C-axis aligned crystalline structure with increased grain size and C-Mi and C-N with rising substrate temperature and power during sputtering. The average visible optical transmittance (T-r) of 80% decreases with the increased d. The lowered T-r in the infrared region with the increment of free carrier absorption is observed. The refractive index and extinction coefficient and dielectric constants increase, and band gap decreases from 2.8 to 2.2 eV, due to the increased C(N )and d. The electrical resistivity decreases from 0.1 to 5.0 E-3 Omega.cm and the work function increases from 2.8 to 3.7 eV with the increased free carrier concentration (N-e). The electrical properties are air-stable stored for 1000 hrs due to the N passiviated surface. The thermoelectric properties, including the Seebeck coefficient (S) and power factor and electric thermal conductivity from 300 to 673 K, are evaluated. The S and extracted electron effective mass are temperature and N-e depended. The electron mean path and scattering time and plasma energy at room temperature are calculated. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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  • Super-Temporal-Resolved Microscopy Reveals Multistep Desorption Kinetics of alpha-Lactalbumin from Nylon.

    Wang, Wenxiao   Shen, Hao   Moringo, Nicholas A   Carrejo, Nicole C   Ye, Fan   Robinson, Jacob T   Landes, Christy F  

    Insight into the mechanisms driving protein-polymer interactions is constantly improving due to advances in experimental and computational methods. In this study, we used super-temporal-resolved microscopy (STReM) to study the interfacial kinetics of a globular protein, alpha-lactalbumin (alpha-LA), adsorbing at the water-nylon 6,6 interface. The improved temporal resolution of STReM revealed that residence time distributions involve an additional step in the desorption process. Increasing the ionic strength in the bulk solution accelerated the desorption rate of alpha-LA, attributed to adsorption-induced conformational changes. Ensemble circular dichroism measurements were used to support a consecutive reaction mechanism. Without the improved temporal resolution of STReM, the desorption intermediate was not resolvable, highlighting both STReM's potential to uncover new kinetic mechanisms and the continuing need to push for better time and space resolution.=20
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  • The ray-tracing mapping operator in an asymmetric atmosphere

    Hong, Zhenjie   Ye, Fan   Guo, Peng  

    In a spherically symmetric atmosphere, the refractive index profile is retrieved from bending angle measurements through Abel integral transform. As horizontal refractivity inhomogeneity becomes significant in the moist low atmosphere, the error in refractivity profile obtained from Abel inversion reaches about 10%. One way to avoid this error is to directly assimilate bending angle profile into numerical weather models. This paper discusses the 2D ray-tracing mapping operator for bending angle in an asymmetric atmosphere. Through simulating computations, the retrieval error of the refractivity in horizontal inhomogeneity is assessed. The step length of 4 rank Runge-Kutta method is also tested. (c) 2007 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.
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  • Potential of Osmotic Membrane Crystallization Using Dense Membranes for Na2CO3 Production in a CO2 Capture Scenario

    Ye, Wenyuan   Wu, Jianhui   Ye, Fan   Zeng, Huiming   Tran, Anh T. K.   Lin, Jiuyang   Luis, Patricia   Van der Bruggen, Bart  

    The potential of a membrane crystallizer equipped with a BW-30 reverse osmosis membrane has been investigated for recovering Na2CO3 from aqueous streams, targeting its application in CO2 mitigation. The effect of various crystallization conditions, such as the concentration of the osmotic solution, the concentration of the Na2CO3 solution, as well as membrane orientations on the process performance has been systematically determined. This dense membrane crystallizer was thought to be better than the membrane contactor applied in previous work due to its higher water flux, marked as 0.210 L.m(-2).h(-1) in forward osmosis (FO) mode and 0.164 L.m(-2).h(-1) in pressure retard osmosis (PRO) mode compared with 0.08 L.m(-2).h(-1) for the membrane contactor. Compared with the PRO mode, the FO mode was found to be a better alternative with higher water permeability and draw solute rejection. The concentration of the osmotic solution was the key parameter to condition the applicability of this system. The long-term operation of the system can be realized without any membrane damage and fouling. In addition, Na2CO3.10H(2)O crystals were obtained with a superhigh purity of 99.98%. Therefore, this osmotic crystallizer equipped with a dense membrane was proven to be an effective alternative for Na2CO3 crystallization for the application in CO2 capture process.
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  • Separation of oily wastewater using titanium modified multi-walled carbon nanotubes as demulsifier

    Jiang, Xia   Kuang, Jiazhe   Mi, Yuanzhu   Huang, Zhiming   Ye, Fan   Zhang, Zejun   Yuan, Huaikui   Luo, Yue  

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  • Joint estimation and compensation for front-end imperfection in MB-OFDM UWB systems

    Ren, Junyan   Ye, Fan   Liu, Liang   Zhou, Jun  

    In this paper; we investigate the analog front-end imperfection in multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems and propose a joint estimation and compensation scheme. The estimation of CFO and SFO is presented on frequency domain; which is robust to frequency dependent I/Q imbalance. After that; I/Q imbalance and channel response is jointly estimated with partial compensation to CFO and SFO. Finally; pilot sub-carriers within OFDM symbols are used to track the residual phase distortion. Simulation results show that the proposed joint estimation and compensation scheme achieves 0.3dB SNR advantage in practical MB-OFDM UWB systems comparing to traditional joint estimation algorithm.
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