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Giant negative electrocaloric effect measured by indirect method in X-ray irradiated P(VDF-TrFE)films

Journal of Materiomics 2024年第3期10卷 624-631页

作者： Bo Li Bin Yang Hong Zhang Jiajia Zhang Qianjin Wang Weishu Liu Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhenGuangdong 518055China Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices Southern University of Science and TechnologyShenzhenChina College of Physics and Electronic Information Yunnan Normal UniversityYunnan Kunming 650500China The Science and Technology on Reliability Physics and Application of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research InstituteGuangzhou 510610China

Flexible solid-state cooling devices with high efficiency are attracted to ferroelectric polymers with excellent negative electrocaloric(EC)*** is challenging to obtain a large negative EC effect in ferroelectric polymers due to the lack of tunable techniques.A giant negative EC response was obtained in the poly(vinylidene fluoride-trifluoroethylene)copolymers(P(VDF-TrFE),70/30,in mole ratio)irra-diated with high-energy *** irradiated P(VDF-TrFE)films showed an adiabatic temperature change of-13.5 K at 40 MV/m under a dose of 5 Mrad(1 Mrad=10^(4) J/kg)obtained by the indirect *** significant negative EC effect is attributed to the enhancement of crystalline due to the entry of polymer molecules into the amorphous to crystalline structure and the reduction of heat ca-pacity due to the increase of *** addition,X-ray irradiation improves the dielectric coefficient from 15 to *** research indicates that irradiation can modify the negative EC properties of ferro-electric polymers for solid-state cooling.

关键词： Negative electrocaloric effects X-rays radiation P(VDF-TrFE)films

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Mode coupling with Fabry-Perot modes in photonic crystal slabs

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Chinese physics B 2024年第8期33卷 90-94页

作者：秦恳胡鹏刘杰向红韩德专 Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 401331China School of Science Chongqing Key Laboratory of New Energy Storage Materials and DevicesChongqing University of TechnologyChongqing 400054China

Fabry–Perot(FP)modes are a class of fundamental resonances in photonic crystal(PhC)*** to their low quality factors,FP modes are frequently considered as background fields with their resonance nature being ***,FP modes can play important roles in some phenomena,as exemplified by their coupling with guided resonance(GR)modes to achieve bound states in the continuum(BIC).Here,we further demonstrate the genuine resonance mode capability of FP modes PhC ***,we utilize temporal coupled-mode theory to obtain the transmittance of a PhC slab based on the FP ***,we construct exceptional points(EPs)in both momentum and parameter spaces through the coupling of FP and GR ***,we identify a Fermi arc connecting two EPs and discuss the far-field polarization *** work elucidates that the widespread FPs in PhC slabs can serve as genuine resonant modes,facilitating the realization of desired functionalities through mode coupling.

关键词： Fabry–Perot mode photonic crystal slab mode coupling exceptional point

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Long-term spatiotemporal variations of ammonia in the Yangtze River Delta region of China and its driving factors

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Journal of Environmental sciences 2025年第4期150卷 202-217页

作者： Jingkai Xue Chengzhi Xing Qihua Li Shanshan Wang Qihou Hu Yizhi Zhu Ting Liu Chengxin Zhang Cheng Liu School of Environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China Key Lab of Environmental Optics&Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Anhui Institute of Optics and Fine Mechanics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes University of Science and Technology of ChinaHefei 230026China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3) Department of Environmental Science and EngineeringFudan UniversityShanghai 200438China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of Environmental Science and Engineering Suzhou University of Science and TechnologySuzhou 215009China

This study focuses on the spatiotemporal distribution,urban-rural variations,and driving factors of ammonia Vertical Column Densities(VCDs)in China’s Yangtze River Delta region(YRD)from 2008 to *** data from the Infrared Atmospheric Sounding Interfer-ometer(IASI),Generalized Additive Models(GAM),and the GEOS-Chem chemical transport model,we observed a significant increase of NH_(3)VCDs in the YRD between 2014 and *** spatial distribution analysis revealed higher NH_(3)concentrations in the northern part of the YRD region,primarily due to lower precipitation,alkaline soil,and intensive agricul-tural ***_(3)VCDs in the YRD region increased significantly(65.18%)from 2008 to *** highest growth rate occurs in the summer,with an annual average growth rate of 7.2%during the period from 2014 to *** emissions dominated NH_(3)VCDs during spring and summer,with high concentrations primarily located in the agricultural areas adjacent to densely populated urban *** within several large urban areas have been discovered to exhibit relatively stable variations in NH_(3)*** rise in NH_(3)VCDs within the YRD region was primarily driven by the reduction of acidic gases like SO_(2),as emphasized by GAM modeling and sensitivity tests using the GEOS-Chem *** concentration changes of acidic gases contribute to over 80%of the interannual variations in NH_(3)*** emphasizes the crucial role of environmental policies targeting the reduction of these acidic *** emission control is urgent tomitigate environmental hazards and secondary particulate matter,especially in the northern YRD.

关键词： Yangtze River Delta Ammonia Spatiotemporal distribution Driving factors

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Global hybrid simulations of soft X-ray emissions in the Earth’s magnetosheath

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Earth and Planetary physics 2024年第1期8卷 47-58页

作者： Jin Guo TianRan Sun San Lu QuanMing Lu Yu Lin XueYi Wang Chi Wang RongSheng Wang Kai Huang School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment University of Science and Technology of ChinaHefei 230026China Collaborative Innovation Center of Astronautical Science and Technology Harbin 150001China National Space Science Center Chinese Academy of SciencesBeijing 100190China Physics Department Auburn UniversityAuburnALUSA

Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas,and it is also the boundary of the solar wind energy transport to the *** X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional(2-D)global view from a *** performing 3-D global hybrid-particle-in-cell(hybrid-PIC)simulations,we obtain soft X-ray images of Earth’s magnetopause under different solar wind conditions,such as different plasma densities and directions of the southward interplanetary magnetic *** all cases,magnetic reconnection occurs at low latitude *** soft X-ray images observed by a hypothetical satellite are shown,with all of the following identified:the boundary of the magnetopause,the cusps,and the *** X-ray emissivity in the magnetosheath is characterized by large amplitude fluctuations(up to 160%);however,the maximum line-of-sight-integrated X-ray intensity matches the tangent directions of the magnetopause well,indicating that these fluctuations have limited impact on identifying the magnetopause boundary in the X-ray ***,the magnetopause boundary can be identified using multiple viewing *** also find that solar wind conditions have little effect on the magnetopause *** Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will provide X-ray images of the magnetopause for the first time,and our global hybrid-PIC simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective,with particle kinetic effects considered.

关键词： magnetopause X-ray emissivity X-ray imaging SMILE global hybrid-PIC simulation

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Novel Sparse Codebook Design for MIMO-SCMA

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IEEE Transactions on Vehicular technology 2025年第5期74卷 8407-8412页

作者： Lei, Tuofeng Luo, Qu Ni, Shuyan Chen, Shimiao Yu, Lisu Xiao, Pei Space Engineering University Key Laboratory of Intelligent Space TTC&O Ministry of Education Beijing101416 China University of Electronic Science and Technology of China National Key Laboratory of Science and Technology on Communications Chengdu610054 China Nanchang University School of Information Engineering Nanchang330031 China Xidian University State Key Laboratory of ISN Xi'an710071 China

The combination of multiple-input multiple-output (MIMO) and sparse code multiple access (SCMA), referred to as MIMO-SCMA, can be leveraged to achieve high spectrum efficiency and provide massive connectivity for future machine-type communication networks. This paper aims to design enhanced sparse codebooks for MIMO-SCMA by jointly combining frequency and spatial diversity over Rayleigh fading channels. First, based on the pairwise error probability (PEP), novel codebook design criteria have been presented, namely the hybrid minimum product distance of the Euclidean distance (MPD-ED) and the minimum Euclidean distance of the superimposed constellation at each frequency element (MED-FE). Then, enhanced mother constellations (MC) are proposed by maximizing the MPD-ED of the MC based on the alternating optimization. Subsequently, the multi-dimensional codebooks are obtained by applying user-specific rotation of the proposed MC to maximize the MED-FE, where the unitary rotations are considered to fully leverage the Euclidean space of the transmit antennas while maintaining the MPD-ED value of the codebook. Finally, numerical results demonstrate that the proposed approach significantly outperforms the state-of-the-art codebooks. © 1967-2012 IEEE.

关键词： Fading channels

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Development of Metrological-grade Spinning Rotor Gauge 24

Development of Metrological-grade Spinning Rotor Gauge

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24th International Vacuum Electronics Conference, IVEC 2023

作者： Xi, Zhenhua Guo, Meiru Jia, Wenjie Ren, Zhengyi Zhang, Huzhong Cheng, Yongjun Lanzhou Institute of Physics Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou China

ISBN: (纸本)9781665473217

The spinning rotor gauge is an internationally recognized high vacuum transfer standard. It is widely used in aerospace, nuclear industry, semiconductor and other fields because of its excellent metrological characteristics and chemical inertness. In order to realize the international equivalence of vacuum quantity in China's science and technology industry. Through the continuous research of key technologies, such as high-quality suspension based on permanent magnet, accurate measurement of axial displacement, residual drag suppression, construction of kinetic model of rotational speed decay rate and high precision detection, the metrological-grade spinning rotor vacuum gauge has been developed. The change of residual drag is less than 0.49 % after 50 minutes of start-up. There is good consistency and linearity in the range of 9 × 10-5 Pa to 1 Pa. © 2023 IEEE.

关键词： Vacuum gages

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High-resolution upper crustal S-wave velocity structure and seismicity distribution around the junction of the Zemuhe and Xiaojiang Fault Zones, Southwest China

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Earth and Planetary physics 2025年第2期9卷 225-238页

作者： Xin Liu HuaJian Yao CuiPing Zhao Ying Liu Song Luo Laboratory of Seismology and Physics of Earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Institute of Advanced Technology University of Science and Technology of ChinaHefei 230088China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaMengcheng Hefei 233500China Chinese Academy of Sciences(CAS)Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China Institute of Earthquake Forecasting China Earthquake AdministrationBeijing 100036China School of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China

The Anninghe–Zemuhe Fault and the Xiaojiang Fault are critical active faults along the middle-eastern boundary of the South Chuan–Dian Block. Many researchers have identified these faults as potential strong-earthquake risk zones. In this study, we leveraged a dense seismic array to investigate the high-resolution shallow crust shear wave velocity(Vs) structure beneath the junction of the Zemuhe Fault Zone and the Xiaojiang Fault Zone, one of the most complex parts of the eastern boundary of the South Chuan–Dian Block. We analyzed the distribution of microseismic events detected between November 2022 and February 2023 based on the fine-scale Vs model obtained. The microseismicity in the study region was clustered into three groups, all spatially related to major faults in this region. These microseismic events indicate near-vertical fault planes, consistent with the fault geometry revealed by other ***, these microseismic events are influenced by the impoundment of the downstream Baihetan Reservoir and the complex tectonic stress near the junction of the Zemuhe Fault Zone and the Xiaojiang Fault Zone. The depths of these microseismic events are shallower in the junction zone, whereas moving south along the Xiaojiang Fault Zone, the microseismic events become ***, we compared our fine-scale local Vs model with velocity models obtained by other researchers and found that our model offers greater detail in characterizing subsurface heterogeneity while demonstrating improved reliability in delineating fault systems.

关键词： Zemuhe–Xiaojiang Fault Zone shallow crust S-wave velocity ambient noise tomography microseismicity

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Study on Temperature Characteristics of Capacitance Diaphragm Gauge 24

Study on Temperature Characteristics of Capacitance Diaphrag...

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24th International Vacuum Electronics Conference, IVEC 2023

作者： Wu, Chengyao Cheng, Yongjun Sun, Wenjun Pei, Xiaoqiang Yang, Qihao Ran, Xin Lanzhou Institute of Physics Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou China

ISBN: (纸本)9781665473217

Capacitance Diaphragm Gauge (CDG) is a type of sensor commonly used under low vacuum with high accuracy and stability. Temperature is one of the most important factors affecting its measurement accuracy. When the ambient temperature changes, the measurement results of CDGs will also drift accordingly. We experimented with the effect of temperature on CDGs and quantified the measurement errors of heated and unheated CDGs in the environment of (-30 50 °C. The error caused by the temperature for the unheated CDG is relatively large. The temperature-pressure error surface we proposed in this paper can effectively reduce the measurement error of the unheated CDG and improve its accuracy. © 2023 IEEE.

关键词： Measurement errors

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Experimental Investigations of Quasi-Coherent Micro-Instabilities in J-TEXT Ohmic Plasmas

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Chinese physics Letters 2024年第5期41卷 47-52页

作者：石鹏庄革程芝峰高丽周乙楠刘永罗景庭李景春 Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China Department of Engineering and Applied Physics School of Physical Sciences University of Science and Technology of ChinaHefei 230026China Shenzhen Key Laboratory of Nuclear and Radiation Safety Institute for Advanced Study in Nuclear Energy&SafetyCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 510640China

Quasi-coherent micro-instabilities is one of the key topics of magnetic confinement fusion. This work focuses on the quasi-coherent spectra of ion temperature gradient(ITG) and trapped-electron-mode instabilities using newly developed far-forward collective scattering measurements within ohmic plasmas in the J-TEXT *** ITG mode is characterized by frequencies ranging from 30 to 100 k Hz and wavenumbers(k_(θρs)) less than 0.3. Beyond a critical plasma density threshold, the ITG mode undergoes a bifurcation, which is marked by a reduction in frequency and an enhancement in amplitude. Concurrently, enhancements in ion energy loss and degradation in confinement are observed. This ground-breaking discovery represents the first instance of direct experimental evidence that establishes a clear link between ITG instability and ion thermal transport.

关键词： ITG mode collective

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Nonperturbative Phenomenons of the Very Early Universe: Resonances in Primordial Fluctuations and Non-Gaussian Tails

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Chinese Astronomy and Astrophysics 2024年第4期48卷 635-682页

作者： Yi-fu, Cai Xin-chen, He Xiao-han, Ma School of Astronomy and Space Science University of Science and Technology of China Hefei 230026 China Deep Space Exploration Laboratory/Department of Astronomy School of Physical Sciences University of Science and Technology of China Hefei 230026 China

In the era of precision cosmology, multi-messenger, high-resolution as well as small-scale cosmological observations have provided profound insights into the early universe, while also presenting new challenges to cosmological perturbation theory based on linear approximation and perturbative expansions. In recent years, the search for primordial gravitational waves and primordial black holes has generated significant research interest in the non-linear and non-perturbative processes in the early universe on small scales. This review paper summarizes the progress in understanding the generation of primordial black holes and gravitational waves at cosmological small scales. Specifically, we focus on the application of the resonance effect depicted by Mathieu equation to study small-scale power spectrum amplification and the induction of observable primordial gravitational waves. Furthermore, we attempt to explore the influence of non-Gaussian tails on primordial black hole formation. Our findings indicate that the resonance effect of the Mathieu equation provides an effective approach to describe non-perturbative and non-linear processes on small scales in the early universe, leading to a better understanding of the mechanisms behind primordial black hole formation and gravitational wave generation. Additionally, the non-perturbative non-Gaussianity may have a significant impact on the formation of primordial black holes. © 2024

关键词： cosmology: inflation—early universe—primordial gravitational waves—non-Gaussianity—primordial black holes

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