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A Pulsar Wind Nebula Origin of the Ultra-high-energy Source 1LHAASO J1929+1846

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Research in Astronomy and Astrophysics 2023年第10期23卷 218-223页

作者： Qi xia Lian-Cheng zhou Jun Fang Department of Astronomy Yunnan UniversityKunming 650091China

1LHAASO J1929+1846 is one of the ultra-high-energy(UHE,E>0.1 PeV)sources in the first catalog ofγ-ray sources detected by the Large High Altitude Air Shower *** has been detected fluxes at 3 TeV for2.48±0.11×10^(-13)TeV^(-1)cm^(-2)s^(-1)with the Water Cherenkov Detector Array and at 50 TeV for0.64±0.06×10^(-16)TeV^(-1)cm^(-2)s^(-1)with the Kilometer Squared Array,but the origin of its UHE emission remains *** pulsar wind nebula(PWN)G54.1+0.3,which is powered by the pulsar PSR 1930+1852with a period of 136 ms and it is detected within a 0°.29 region around the centroid of 1LHAASO J1929+*** explore whether G54.1+0.3 is capable of producing the UHE radiation of 1LHAASO J1929+***,the data with Fermi Large Area Telescope for the PWN is analyzed to obtain the GeV ***,the multiband nonthermal fluxes for the nebula are investigated based on a one-zone time-dependent *** the model,we assume the spin-down energy of the pulsar is persistently injected into particles(electrons and positrons)and magnetic field in the PWN,and these high-energy particles produce multiband non-thermal radiation from radio toγ-rays via synchrotron radiation and inverse Compton *** reproduce the spectral energy distribution of PWN G54.1+0.3 with reasonable *** result indicates that the UHEγ-ray source 1LHAASO J1929+1846possibly originates from PWN G54.1+0.3.

关键词： radiation mechanisms:non-thermal ISM:supernova remnants gamma-rays:stars

Comparison of decision-making in neonatal care between China and Japan

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World Journal of Pediatrics 2019年第1期15卷 85-91页

作者： Hidehiko Maruyama Yuka Shibata Xing-Ge xia Yun-xia Sun Shao-ru He Yushi Ito Division of Neonatology Center for Maternal-FetalNeonatal and Reproductive MedicineNational Center for Child Health and DevelopmentTokyoJapan Division of NICU Guangdong General Hospital Guangdong Academy of Medical SciencesGuangdongChina

Background Various differences between China and Japan in approaches to medical treatment have been noted,but a few studies have examined differences in medical decision-making,especially in neonatal *** aim of this study was to clarify these differences by means of a *** The subjects were physicians on the staff of NICUs in China and *** study questionnaire consisted of three parts dealing with the general characteristics of the participants,questions about treatment strategies for hypothetical,critically ill infants,and general questions about the treatment of foreign *** Likert scale was used to assess the treatment strategies and the results were analyzed *** analysis by age,sex,and medical and NICU experience was also *** The proportion of respondents in the Chinese and Japanese groups was 26/26 (100%) and 26/31 (84%),*** was a significant difference between the Chinese and Japanese groups for 8 of 75 questions;Chinese physicians chose the positive treatment or examination options for these eight questions unlike their Japanese *** responses of the younger,less experienced physicians in both countries were more similar to each other,and more positive than those of their older,more experienced *** Chinese physicians showed a more positive attitude toward examination and treatment,whereas Japanese physicians showed a more cautious attitude.

关键词： Behavioral style China Decision-making Directive style Japan

Uniform and Semi-uniform Convergence for Discontinuous Skew-product Transformation and Observation

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Acta Mathematica Sinica,English Series 2021年第2期37卷 333-344页

作者： xia PAN Zuo Huan ZHENG Zhe zhou College of Liberal Arts and Sciences National University of Defense TechnologyChangsha 410073P.R.China Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190P.R.China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049P.R.China ollege of Mathematics and Statistics Hainan Normal UniversityHaikou 571158P.R.China

In this paper, for a discontinuous skew-product transformation with the integrable observation function, we obtain uniform ergodic theorem and semi-uniform ergodic theorem. The main assumptions are that discontinuity sets of transformation and observation function are ignorable in some measure-theoretical sense. The theorems extend the classical results which have been established for continuous transformations and continuous observation functions.

关键词： Skew-product transformation uniform ergodicity semi-uniform ergodicity

Local Polynomial-Brunk Estimation in Semi-Parametric Monotone Errors-in-Variables Model with Right-Censored Data

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Journal of Systems Science & Complexity 2015年第4期28卷 938-960页

作者： xia Wei CHEN Zhao WU Wuqing zhou Jianjun Department of Finance and Statistics University of Science and TechnologyHefei Department of Operations Research and Financial Engineering Princeton University School of Business Renmin University of China School of Mathematics and Statistics Yunnan University

This paper introduces a semi-parametric model with right-censored data and a monotone constraint on the nonparametrie part. The authors study the local linear estimators of the parametric coefficients and apply B-spline method to approximate the nonparametric part based on grouped data. The authors obtain the rates of convergence for parametric and nonparametric estimators. Moreover, the authors also prove that the nonparametric estimator is consistent at the boundary. At last, the authors investigate the finite sample performance of the estimation.

关键词： B-spline grouped brunk local polynomial monotone regression right-censored semi-parametric model.

Influence and mechanism of N-(3-oxooxtanoyl)-L-homoserine lactone(C_8-oxo-HSL) on biofilm behaviors at early stage

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Journal of Environmental Sciences 2012年第12期24卷 2035-2040页

作者： Siqing xia Lijie zhou Zhiqiang Zhang Jixiang Li State Key Laboratory of Pollution Control and Resource Reuse Tongji UniversityShanghai 200092China Sustainable Technology Research Center Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201210China

N-acyl-homoserines quenching, enzymatic quenching of bacterial quorum sensing, has recently applied to mitigate biofilm in membrane bioreactor. However, the effect of AHLs on the behavior of biofilm formation is still sparse. In this study, Pseudomonas aeruginosa biofilm was formed on ultra-filtration membrane under a series of N-（3-0xooxtanoyl）-L-homoserine lactone （C8-0xo-HSL） concentrations. Diffusing Cs-oxo-HSL increased the growth rate of cells on biofilm where the concentration of Cs-oxo-HSL was over 10-7 g/L. The C8-0xo-HSL gradient had no observable influence on cell density and extracellular polymeric substances of biofilm with over 10-7 g/L Cs-oxo-HSL. Surprisingly, 10-11-10-8 g/L of Cs-Oxo-HSL had no effect on cell growth in liquid culture. The cell analysis demonstrated that the quorum sensing system might enhance the growth of neighboring cells in contact with surfaces into biofilm and may influence the structure and organization of biofilm.

关键词： quorum sensing C8-oxo-HSL biofilm formation ultra-filtration membrane cell density extracellular polymericsubstances

New insight into adsorption characteristics and mechanisms of the biosorbent from waste activated sludge for heavy metals

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Journal of Environmental Sciences 2016年第7期28卷 248-256页

作者： Yun zhou Zhiqiang Zhang Jiao Zhang Siqing xia Key Laboratory of Yangtze River Water Environment Ministry of Education College of Environmental Science and Engineering Tongji University State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and Engineering Tongji University Swette Center for Environmental Biotechnology Arizona State University School of Civil Engineering and Transportation Shanghai Technical College of Urban Management

The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2＋and Zn2＋in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients（above 0.99 for both metal ions） and insignificant lack of fit（p = 0.0838 and 0.0782 for Pb2＋and Zn2＋, respectively）. Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation（between –NH2,-CN and metal ions） and ion-exchange（between –COOH and metal ions）. The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.

关键词： Waste activated sludge Biosorbent Adsorption Metal ions Response surface methodology(RSM)

Removal of Pb(Ⅱ) from aqueous solutions using waste textiles/poly(acrylic acid) composite synthesized by radical polymerization technique

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Journal of Environmental Sciences 2018年第5期30卷 368-377页

作者： Tao zhou Fafa xia Yue Deng Youcai Zhao The State Key Laboratory of Pollution Control and Resource Reuse School of Environmental Science and Engineering Tongji University

Waste textiles（WTs） are the inevitable outcome of human activity and should be separated and recycled in view of sustainable development. In this work, WT was modified through grafting with acrylic acid（AA） via radical polymerization process using ceric ammonium nitrate（CAN） as an initiator and microwave and/or UV irradiation as energy supply. The acrylic acid-grafted waste textiles（WT-g-AA） thus obtained was then used as an adsorbent to remove Pb（Ⅱ） from Pb（Ⅱ）-containing wastewater. The effects of p H, initial concentrations of Pb（Ⅱ） and adsorbent dose were investigated, and around 95% Pb（Ⅱ） can be removed from the aqueous solution containing 10 mg/L at p H 6.0–8.0. The experimental adsorption isotherm data was fitted to the Langmuir model with maximum adsorption capacity of35.7 mg Pb/g WT-g-AA. The Pb-absorbed WT-g-AA was stripped using dilute nitric acid solution and the adsorption capacity of Pb-free material decreased from 95.4%（cycle 1） to91.1%（cycle 3）. It was considered that the WT-g-AA adsorption for Pb（Ⅱ） may be realized through the ion-exchange mechanism between ／COOH and Pb（Ⅱ）. The promising results manifested that WT-g-AA powder was an efficient, eco-friendly and reusable adsorbent for the removal of Pb（Ⅱ） from wastewater.

关键词： Adsorption Pb(Ⅱ) Waste textiles Graft copolymefization

A parallel data generator for efficiently generating “realistic” social streams

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Frontiers of Computer Science 2019年第5期13卷 1072-1101页

作者： Chengcheng YU Fan xia Weining QIAN Aoying zhou College of Computer and Information Engineering Shanghai Polytechnic University Shanghai 201209 China School of Data Science and Engineering East China Normal University Shanghai 200062 China

A social stream refers to the data stream that records a series of social entities and the dynamic interac-tions between two entities. It can be employed to model the changes of entity states in numerous applications. The social streams, the combination of graph and streaming data, pose great challenge to efficient analytical query processing, and are key to better understanding users' behavior. Considering of privacy and other related issues, a social stream genera-tor is of great significance. A framework of synthetic social stream generator (SSG) is proposed in this paper. The gener-ated social streams using SSG can be tuned to capture sev-eral kinds of fundamental social stream properties, includ-ing patterns about users' behavior and graph patterns. Ex-tensive empirical studies with several real-life social stream data sets show that SSG can produce data that better fit to real data. It is also confirmed that SSG can generate social stream data continuously with stable throughput and memory consumption. Furthermore, we propose a parallel implemen-tation of SSG with the help of asynchronized parallel pro-cessing model and delayed update strategy. Our experiments verify that the throughput of the parallel implementation can increase linearly by increasing nodes.

关键词： social stream data generator SSG parallel generation

Experimental study of a controlled variable double-baffle distortion generator engine test rig

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Chinese Journal of Aeronautics 2018年第9期31卷 1880-1893页

作者： Aiguo xia Xudong HUANG Wei TUO Ming zhou School of Aerospace Engineering Tsinghua University Beijing Aeronautical Technology Research Center

In order to explore the total-pressure distortion test assessment method for a turbofan engine, a Controlled Variable Double-Baffle Distortion Generator(CVDBDG) with a horizontal symmetry moving form was developed, which can adjust the steady-state and time–variant distortion separately in real time. The inlet total-pressure distortion test was conducted on an afterburner turbofan engine. The distortion parameters of CVDBDG and the instability characteristics of the engine were measured. The experimental data were modeled and analyzed by using back propagation artificial neural networks, and the work envelope of CVDBDG was obtained. Based on the analysis of the data on the engine’s instability, the properties of CVDBDG used for the stability assessment were preliminarily evaluated. The results show that CVDBDG can simulate both steady-state and time–variant distortions simultaneously in a range determined by three *** the condition of symmetric double baffles, a critical depth of insertion exists, beyond which the symmetric baffles will generate an asymmetric flow field. In the case of double baffles, compared to a single baffle, the engine exhibited different instability characteristics. Based on CVDBDG, it is expected that more efficient engine stability and durability assessment methods can be developed.

关键词： Distortion generator Engine stability Inlet flow Inlet total-pressure distortion Turbofan engines