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Spatial distribution of ion polytropic index joint-modulated by temperature anisotropy and MHD disturbances in the southern high latitude magnetosheath

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Science China(Technological Sciences) 2018年第3期61卷 381-388页

作者： pang xuexia CAO JinBin DENG ZeChao JIA PengYing School of Space and Environment Beihang University Hebei Key Lab of Optic-electronic Information and Materials College of Physics Science and Technology Hebei University

Using the Cluster data from 2001 to 2010, we studied spatial distribution of effective ion polytropic index in the southern high latitude magnetosheath, and joint-modulation of ion polytropic index by temperature anisotropy and MHD disturbances. The magnetosheath ions generally experience various polytropic processes with different polytropic index. The median polytropic indexes of magnetosheath ions in the GSE X-Y plane decrease toward the bow shock. Near the magnetopause, the median polytropic indexes are basically between isothermal and adiabatic except in the duskside flank close to the terminator. The analysis of correlation coefficient of perturbed ion number density with parallel magnetic field CC_δnδB_‖ and ion temperature anisotropy parameter A_T, indicates that the dominant MHD disturbance near magnetopause is slow mode with larger ion temperature anisotropy, and there are various modes of MHD disturbances with insignificant ion temperature anisotropy near the bow *** polytropic index modulated by slow mode disturbances is generally larger than that modulated by fast mode disturbances, and the larger ion temperature anisotropy, the larger polytropic index. The median polytropic indexes modulated jointly by slow mode disturbances and the strong ion temperature anisotropy can be larger than 1.0, while those modulated by fast mode disturbances and weak temperature anisotropy can be even possibly close to zero. Moreover, because of pronounced dusk-favored asymmetry of ion temperature anisotropy, the median polytropic index in the dawnside flank of the magnetosheath near the terminator is smaller than that in the duskside flank of the magnetosheath. The good correspondence between the distributions of median polytropic indexes and ion temperature anisotropy and MHD disturbances indicates that the ion temperature anisotropy and MHD disturbances determine the distribution of the polytropic index in the magnetosheath.

关键词： polytropic index magnetosheath temperature anisotropy

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A double‐mode planar argon plume produced by varying the distance from an atmospheric pressure plasma jet

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High Voltage 2023年第6期8卷 1161-1167页

作者： Kaiyue Wu Jingnan Liu Jiacun Wu Mo Chen Junxia Ran xuexia pang Pengying Jia Xuechen Li Chenhua Ren College of Physics Science and Technology Hebei UniversityBaodingChina North China Electric Power University BeijingChina

Atmospheric pressure planar plumes are desirable for the applications of low temperature plasmas,such as rapid modification of large‐scale *** to now,only single‐mode planar plumes with either a streamer mode or a filamentary mode have been reported in the *** from the single‐mode planar plumes,a double‐mode argon planar plume has been generated in this article,which operates in the streamer mode with a larger distance away from a plasma jet and transits to the filamentary mode with decreasing the *** characteristics and plasma parameters are compared for the two *** indicate that the streamer mode and the filamentary mode correspond to pulsed and humped discharges *** photography reveals that the streamer‐mode plume is composed of stochastically branching streamers,while the filamentary‐mode plume results from a series of moving filaments similar to those in barrier *** contrast to the streamer mode,the filamentary mode has lower excited electron temperature and vibrational temperature,whereas higher electron density and gas *** addition,better hydrophilicity of polyethylene terephthalate surface is achieved in the filamentary mode.

关键词： temperature planar double

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Case study of small scale polytropic index in the central plasma sheet

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Science China Earth Sciences 2015年第11期58卷 1993-2001页

作者： pang xuexia CAO JinBin LIU WenLong MA YuDuan LU HaoYu YANG JunYing LI LiuYuan LIU Xu WANG Jing WANG TieYan YU Jiang College of Physics Science and Technology Hebei University Hebei Key Laboratory of Optic-electronic Information and Materials Space Science Institute School of Astronautics Beihang University

This paper studies the effective polytropic index in the central plasma sheet （CPS） by using the method of Kartalev et al. （2006）, which adopts the denoising technique of Haar wavelet to identify the homogeneous MHD Bernoulli integral （MBI） and has been frequently used to study the polytropic relation in the solar wind. We chose the quiet CPS crossing by Cluster C1 during the interval 08：51：00-09：19：00 UT on 03 August 2001. In the central plasma sheet, thermal pressure energy per unit mass is the most important part in MBI, and kinetic energy of fluid motion and electromagnetic energy per unit mass are less important. In the MBI, there are many peaks, which correspond to isothermal or near isothermal processes. The interval lengths of homogenous MBI regions are generally less than 1 min. The polytropic indexes are calculated by linearly fitting the data of lnp and Inn within a 16 s window, which is shifted forward by 8 s step length. Those polytropic indexes with IRI ≥0.8 （R is the correlation coefficient between lnp and inn） and p-value≤0.1 in the homogeneous regions are almost all in the range of [0, 1]. The mean and median effective polytropic indexes with high R and low p-value in homogeneous regions are 0.34 and 0.32 respectively, which are much different from the polytropic index obtained by traditional method （αtrad=-0.15）. This result indicates that the CPS is not uniform even during quiet time and the blanket applications of polytropic law to plasma sheet may return misleading value of polytropic index. The polytropic indexes in homogeneous regions with a high correlation coefficient basically have good regression significance and are thus credible. These results are very important to understand the energy transport in magnetotail in the MHD frame.

关键词： polytropic index central plasma sheet MHD Bernoulli integral

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Influence of oxygen addition on the discharge characteristics of an argon plasma jet at atmospheric pressure

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Chinese Physics B 2022年第6期31卷 535-540页

作者： Junyu Chen Na Zhao Jiacun Wu Kaiyue Wu Furong Zhang Junxia Ran Pengying Jia xuexia pang and Xuechen Li College of Physics Science&Technology Hebei UniversityBaoding 071002China School of Mathematics and Physics Handan UniversityHandan 056005China Institute of Life Science&Green Development Hebei UniversityBaoding 071002China

Plasma jet is an important low-temperature plasma source in extensive application *** promote the production of active oxygen species,oxygen is often introduced into the inert working ***,the influence of oxygen content on the discharge characteristics of an argon plasma jet is not *** to this status,an argon plasma jet in a singleelectrode geometry is employed to investigate the influence of oxygen concentration(CO)on discharge *** indicate that with increasing CO(≤0.6%),the plume transits from a diffuse morphology to a hollow *** and optical measurements reveal that both discharge number per voltage cycle and pulse intensity alter with varying ***,discharge morphologies of negative and positive discharges obtained by fast photograph also shift with varying ***,optical emission spectra are collected to investigate atomic CO,electron density,and electron *** results mentioned above are explained qualitatively,which are believed to be of great significance for the applications of atmospheric pressure plasma jet.

关键词： plasma jet oxygen addition fast photography optical emission spectra

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Argon plume transition from a hollow swell to a diffuse swell with increasing amplitude of a trapezoidal voltage

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Plasma Science and Technology 2022年第8期24卷 84-90页

作者： Junyu CHEN Furong ZHANG Pengying JIA Na ZHAO Kaiyue WU Jiacun WU Junxia RAN xuexia pang Xuechen LI College of Physics Science&Technology Hebei UniversityBaoding 071002People's Republic of China Institute of Life Science&Green Development Hebei UniversityBaoding 071002People's Republic of China School of Mathematics and Physics Handan UniversityHandan 056005People's Republic of China

Atmospheric pressure plasma jets can generate a remote plasma plume,which usually presents a conical or cylindrical *** a few morphologies being observed,efforts should be made to obtain more plume structures because streamer dynamics may be revealed from *** this purpose,an argon plasma plume excited by a trapezoidal voltage is investigated,which presents two kinds of swells(a hollow swell and a diffuse swell)with increasing voltage amplitude(V).The results indicate that there are two positive discharges(Dand D)and one negative discharge(D)per voltage cycle for both of the *** increasing V,the inception voltage and discharge intensity increase for every positive discharge,while they decrease for the negative *** photography reveals that the positive streamer(D)leaves different tracks in the two swells,which are curved in the hollow swell and randomly branched in the diffuse *** different tracks of Dare explained with the consideration of applied field strength and residual positive ions of *** existence of residual positive ions is finally verified from optical emission spectra.

关键词： plasma jet plume morphology streamer behavior optical emission spectra

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A Novel Hybrid Ensemble Learning Approach for Enhancing Accuracy and Sustainability in Wind Power Forecasting

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Computers, Materials & Continua 2024年第5期79卷 3373-3395页

作者： Farhan Ullah xuexia Zhang Mansoor Khan Muhammad Abid Abdullah Mohamed School of Electrical Engineering Southwest Jiaotong UniversityChengdu611756China College of Intelligent Manufacturing and Control Engineering Qilu Institute of TechnologyJinan250200China College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin150001China Research Centre Future University in EgyptNew Cairo11835Egypt

Accurate wind power forecasting is critical for system integration and stability as renewable energy reliance *** approaches frequently struggle with complex data and non-linear connections. This article presentsa novel approach for hybrid ensemble learning that is based on rigorous requirements engineering *** approach finds significant parameters influencing forecasting accuracy by evaluating real-time Modern-EraRetrospective Analysis for Research and Applications (MERRA2) data from several European Wind farms usingin-depth stakeholder research and requirements elicitation. Ensemble learning is used to develop a robust model,while a temporal convolutional network handles time-series complexities and data gaps. The ensemble-temporalneural network is enhanced by providing different input parameters including training layers, hidden and dropoutlayers along with activation and loss functions. The proposed framework is further analyzed by comparing stateof-the-art forecasting models in terms of Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE),respectively. The energy efficiency performance indicators showed that the proposed model demonstrates errorreduction percentages of approximately 16.67%, 28.57%, and 81.92% for MAE, and 38.46%, 17.65%, and 90.78%for RMSE for MERRAWind farms 1, 2, and 3, respectively, compared to other existingmethods. These quantitativeresults show the effectiveness of our proposed model with MAE values ranging from 0.0010 to 0.0156 and RMSEvalues ranging from 0.0014 to 0.0174. This work highlights the effectiveness of requirements engineering in windpower forecasting, leading to enhanced forecast accuracy and grid stability, ultimately paving the way for moresustainable energy solutions.

关键词： Ensemble learning machine learning real-time data analysis stakeholder analysis temporal convolutional network wind power forecasting

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Integrated assessment of yield,nitrogen use efficiency and ecosystem economic benefits of use of controlled-release and common urea in ratoon rice production

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Journal of Integrative Agriculture 2024年第9期23卷 3186-3199页

作者： Zijuan Ding Ren Hu Yuxian Cao Jintao Li Dakang Xiao Jun Hou xuexia Wang College of Agriculture Yangtze University/MARA Key Laboratory of Sustainable Crop Production in the Middle Reaches of the Yangtze River(Co-construction by Ministry and Province)Jingzhou 434025China College of Life Science Yangtze UniversityJingzhou 434025China Institute of Plant Nutrition Resources and EnvironmentBeijing Agricultural Forestry Academy SciencesBeijing 100097China

Controlled-release urea(CRU)is commonly used to improve the crop yield and nitrogen use efficiency(NUE).However,few studies have investigated the effects of CRU in the ratoon rice *** rice is the practice of obtaining a second harvest from tillers originating from the stubble of the previously harvested main *** this study,a 2-year field experiment using a randomized complete block design was conducted to determine the effects of CRU on the yield,NUE,and economic benefits of ratoon rice,including the main crop,to provide a theoretical basis for fertilization of ratoon *** experiment included four treatments:(i)no N fertilizer(CK);(ii)traditional practice with 5 applications of urea applied at different crop growth stages by surface broadcasting(FFP);(iii)one-time basal application of CRU(BF1);and(iv)one-time basal application of CRU combined with common urea(BF2).The BF1 and BF2 treatments significantly increased the main crop yield by 17.47 and 15.99%in 2019,and by 17.91 and 16.44%in 2020,respectively,compared with FFP *** BF2 treatment achieved similar yield of the ratoon crop to the FFP treatment,whereas the BF1 treatment significantly increased the yield of the ratoon crop by 14.81%in 2019 and 12.21%in 2020 compared with the FFP *** BF1 and BF2 treatments significantly improved the 2-year apparent N recovery efficiency,agronomic NUE,and partial factor productivity of applied N by 11.47-16.66,27.31-44.49,and 9.23-15.60%,respectively,compared with FFP *** BF1 and BF2 treatments reduced the chalky rice rate and chalkiness of main and ratoon crops relative to the FFP ***,emergy analysis showed that the production efficiency of the BF treatments was higher than that of the FFP *** BF treatments reduced labor input due to reduced fertilization times and improved the economic benefits of ratoon *** with the FFP treatment,the BF1 and BF2 treatments increased the net income by 14.21-16

关键词： ratoon rice controlled-release urea yield nitrogen use efficiency economic benefit

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Facile preparation of ZIF-8/ZIF-67-derived biomass carbon composites for highly efficient electromagnetic wave absorption

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Chinese Chemical Letters 2024年第9期35卷 376-381页

作者： xuexia Lin Yihui Zhou Jiafu Hong Xiaofeng Wei Bin Liu Chong-Chen Wang College of Chemical Engineering Huaqiao UniversityXiamen 361021China Beijing Key Laboratory of Functional Materials for Building Structure and Environment Remediation Beijing University of Civil Engineering and ArchitectureBeijing 100044China College of Materials Science and Engineering Huaqiao UniversityXiamen 361021China

Biomass absorbing materials have received increasing attention for electromagnetic wave(EMW)absorption field absorbing materials due to its low density and high dielectric ***,the biomass EMW absorbing materials often suffer from the insufficient magnetic loss and impedance *** this work,a facile ZIF-8/ZIF-67-derived biomass composites(CoZnO@BPC)was prepared for high-performance EMW absorption based on multi-component micro,nano structures metal particles and xanthoce sorbifolia bunge shells-derived biomass porous carbon(BPC).The dielectric loss and/or magnetic loss abilities of CoZnO@BPC composites were adjusted by changing the mass ratio of Zn^(2+)to Co^(2+)*** the filled amount of 20 wt%,Co Zn O@BPC exhibited excellent EMW absorption with the minimum reflection loss(RL)at 15.84 GHz is-50.2 dB,and the matching thickness is only 1.7 *** adjusting the ZIFs mass ratio,the effective absorption bandwidth(EAB)can be up to 5.92 GHz(from 12.08 GHz to 18 GHz),and the matching thickness is only 1.9 *** results provide a new insight for the economical and efficient preparation of lightweight and advanced microwave absorbing materials.

关键词： Biomass Metal organic framework EMW absorption Dielectric loss Magnetic loss

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Hybrid 2D/3D Graphitic Carbon Nitride-Based High-Temperature Position-Sensitive Detector

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Energy & Environmental Materials 2024年第1期7卷 275-283页

作者： xuexia Chen Dongwen Yang Xun Yang Qing Lou Zhiyu Liu Yancheng Chen Chaofan Lv Lin Dong Chongxin Shan Henan Key Laboratory of Diamond Optoelectronic Materials and Devices Key Laboratory of Material PhysicsMinistry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China

Ultraviolet position-sensitive detectors(PSDs)are expected to undergo harsh environments,such as high temperatures,for a wide variety of applications in military,civilian,and ***,no report on relevant PSDs operating at high temperatures can be found up to ***,we design a new 2D/3D graphitic carbon nitride(g-C_(3)N_(4))/gallium nitride(GaN)hybrid heterojunction to construct the ultraviolet high-temperature-resistant *** g-C_(3)N_(4)/GaN PSD exhibits a high position sensitivity of 355 mV mm^(-1),a rise/fall response time of 1.7/2.3 ms,and a nonlinearity of 0.5%at room *** ultralow formation energy of-0.917 eV atom^(-1)has been obtained via the thermodynamic phase stability calculations,which endows g-C_(3)N_(4)with robust stability against *** merits of the strong built-in electric field of the 2D/3D hybrid heterojunction and robust thermo-stability of g-C_(3)N_(4),the g-C_(3)N_(4)/GaN PSD delivers an excellent position sensitivity and angle detection nonlinearity of 315 mV mm^(-1)and 1.4%,respectively,with high repeatability at a high temperature up to 700 K,outperforming most of the other counterparts and even commercial silicon-based *** work unveils the high-temperature PSD,and pioneers a new path to constructing g-C_(3)N_(4)-based harsh-environment-tolerant optoelectronic devices.

关键词： graphitic carbon nitride high-temperature stability lateral photovoltaic effect position-sensitive detectors two-dimensional materials

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Analysis of Effluent Outfall Problems and Their Classification and Regulation Countermeasures

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Agricultural Biotechnology 2024年第1期13卷 62-65页

作者： xuexia JIANG Xiange WU College of Environmental and Chemical Engineering Zhaoqing UniversityZhaoqing 526061China

Effluent outfalls are an important exit for pollutants discharged from the source flowing into environmental water bodies,as well as an important guarantee for the ecological environment of natural water *** response to main problems of large and diverse effluent outfalls,as well as their monitoring analysis,tracing and regulation in China,classification and regulation countermeasures were proposed based on the characteristics of effluent *** is suggested that a comprehensive management and control system should be built by improving the management and control system,upgrading monitoring techniques and strengthening social supervision and public education,so as to provide a scientific basis for the supervision and management of effluent outfalls in China and help promote the improvement of water quality and the sustainable development and utilization of water resources.

关键词： Effluent outfalls Monitoring and analysis Classification and regulation Environmental management

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