检索结果-南通市图书馆

Internal flow in sessile droplets induced by substrate oscillation:towards enhanced mixing and mass transfer in microfluidic systems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2024年第3期10卷 369-379页

作者： Tianyi Zhang Peng Zhou Terrence Simon Tianhong cui Department of Mechanical Engineering University of MinnesotaMinneapolisMN 55455USA

The introduction of flows within sessile droplets is highly effective for many lab-on-a-chip chemical and biomedical ***,generating such flows is difficult due to the typically small droplet ***,we present a simple,non-contact strategy to generate internal flows in sessile droplets for enhancing mixing and mass *** flows are driven by actuating a rigid substrate into oscillation with certain amplitude distributions without relying on the resonance of the droplet *** oscillation characteristics and corresponding flow patterns are documented *** indices and mass transfer coefficients of sessile droplets on the substrate surface are measured using optical and electrochemical *** demonstrate complete mixing within the droplets in 1.35 s and increases in mass transfer rates of more than seven times static *** of concept was conducted with experiments of silver nanoparticle synthesis and with heavy metal ion sensing employing the sessile droplet as a microreactor for synthesis and an electrochemical cell for *** degrees of enhancement of synthesis efficiency and detection sensitivity attributed to the internal flows are experimentally documented.

关键词： mixing oscillation synthesis

Geometry characteristics and wide temperature behavior of silicon-based GaN surface acoustic wave resonators with ultrahigh quality factor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第2期67卷 267-278页

作者： Guofang YU Renrong LIANG Haiming ZHAO Lei XIAO Jie cui Yue ZHAO Wenpu cui Jing WANG Jun XU Jun FU Tianling REN School of Integrated Circuits Tsinghua University Beijing National Research Center for Information Science Technology Tsinghua University

Surface acoustic wave(SAW) resonators with an ultrahigh Q-factor are designed and fabricated on silicon-based gallium nitride(GaN/Si). The temperature-dependent performance is characterized over a wide range, from 10 to 500 K. Finite element analysis is employed to guide the design of the SAW resonator from indications of the Rayleigh mode and weak propagation direction dependence of SAW in the c-plane of GaN/Si. The SAW resonator with 100 pairs of interdigital transducers(IDT), 100 pairs of grating reflectors(GR) for each side, aperture size of 80 μm, metallization ratio of 0.5, and electrode width of 500 nm resonates at 1.9133 GHz accordingly with an ultrahigh Q-factor of 7622 at room temperature, which contributes the fr× Qr, up to 14.583×1012Hz. A resonator operating over 10 to 500 K indicates an approximately linear decreasing temperature dependence above 280 K while being approximately constant below 40 K. The fitting to resonator characteristics using the modified Butterworth Van Dyke(m BVD) model reveals a reduction in both the electrode and mechanical losses while worsening the dielectric loss with cooling down.

关键词： GaN/Si SAW resonator ultrahigh Q-factor temperature-dependent performance mBVD losses

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

滑道运输工艺在综采工作面搬家中的应用实践

机械管理开发 2020年第8期35卷 202-203页

作者：崔志刚山西大同煤矿集团有限公司煤峪口矿山西大同037001

针对煤峪口矿在8605工作面搬家倒面工作中采用滑道运输工作的时间,首先介绍了滑道运输综采支架应用情况及搬家前的准备工作,并对滑道运输系统相关参数进行计算。实践表明,借助滑道支架在井下能够更安全地长距离运输,有效解决了工作面搬... 详细信息

针对煤峪口矿在8605工作面搬家倒面工作中采用滑道运输工作的时间,首先介绍了滑道运输综采支架应用情况及搬家前的准备工作,并对滑道运输系统相关参数进行计算。实践表明,借助滑道支架在井下能够更安全地长距离运输,有效解决了工作面搬家的运输问题,节约搬运所需时间,从整体上提高了作业效率。

关键词：搬家滑道运输实践

Finite Element Method for Transient Electric Field by Using Indirect Laplace Transform with High Accuracy

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第1期10卷 401-411页

作者： Teng Wen Xiang cui Xuebao Li Sijia Liu Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China China Electric Power Planning&Engineering Institute Beijing 100120China

This paper focuses on the finite element method in the complex frequency domain(CFD-FEM)for the transient electric ***,the initial value and boundary value problem of the transient electric field under the electroquasistatic field in the complex frequency domain is *** addition,the finite element equation and the constrained electric field equation on the boundary are ***,the indirect algorithm of the numerical inverse Laplace transform is *** on it,the calculation procedures of the CFD-FEM are illustrated in ***,the step response,zero-state response under the positive periodic square waveform(PPSW)voltage,and the zero-input response by the CFD-FEM with direct algorithm and indirect algorithm are ***,the reason for the numerical oscillations of the zero-state response under the PPSW voltage is analyzed,and the method to reduce oscillations is *** results show that the numerical accuracy of the indirect algorithm of the CFD-FEM is more than an order of magnitude higher than that of the direct algorithm when calculating the step response of the transient electric *** proposed method can significantly reduce the numerical oscillations of the zero-state response under the PPSW *** proposed method is helpful for the calculation of the transient electric field,especially in the case of frequency-dependent parameters.

关键词： Electroquasistatic field transient electric field finite element method complex frequency domain numerical Laplace transform

Eutectogel-based self-powered wearable sensor for health monitoring in harsh environments

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 5559-5568页

作者： Junpeng Wu Xinru Teng Lu Liu Hongzhi cui Xiaoyi Li College of Materials Science and Engineering Ocean University of ChinaQingdao 266100China Key Lab for Special Functional Materials of Ministry of Education School of Materials Science and EngineeringHenan UniversityKaifeng 475004China

Triboelectric nanogenerators(TENG)have emerged as a highly promising energy harvesting technology,attracting significant attention in recent years for their broad ***-based TENGs,with superior stretchability and sensitivity,have been widely reported as wearable ***,the traditional hydrogel-based TENGs suffer from freezing at low temperatures and drying at high temperatures,resulting in *** this study,we introduce an anti-freezing eutectogel,which uses a deep eutectic solvent(DES),to improve the stability and electrical conductivity of TENGs in harsh environmental *** eutectogel-based TENG(E-TENG)produces an open-circuit voltage of 776 V,a short-circuit current of 1.54μA,and a maximum peak power of 1.1 ***,the E-TENG exhibits exceptional mechanical properties with an elongation at a break of 476%under ***,it maintains impressive performances across a wide temperature range from−18 to 60℃,with conductivities of 2.15 S/m at−10℃and 1.75 S/m at−18℃.Based on the excellent weight stability of the E-TENG sensor,motion sensing can be achieved in the air,and even ***,the versatility of the E-TENG can serve as a wearable sensor,by integrating it with Bluetooth *** self-powered E-TENG can monitor various human motion signals in real-time and send the health signals directly to mobile *** research paves a new road for the applications of TENGs in harsh environments,offering wireless flexible sensors with real-time health signal monitoring capabilities.

关键词： triboelectric nanogenerators self-powered harsh environment health monitoring Eutectogel

A new scheme of climate-vegetation regionalization in the Hengduan Mountains Region

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 751-768页

作者： Xueqin ZHANG Xiaoming XU Xiang LI Peng cui Du ZHENG Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China China-Pakistan Joint Research Center on Earth Sciences Chinese Academy of Sciences-Higher Education Commission of PakistanIslamabad 45320Pakistan

The Hengduan Mountains Region(HMR) is essential for the future ecological protection, clean energy production,Sichuan-Xizang and Yunnan-Xizang railways, and other major infrastructure projects in China. The distributions of climate and vegetation exhibit significant regional differentiation and vertical zonality due to the rugged longitudinal ranges and gorges and the complex disaster-prone environments in HMR. Therefore, it is urgent to develop the climate-vegetation regionalization in HMR to effectively satisfy the national requirements such as agricultural production and ecological protection, mountain disaster risk prevention, and major project construction. We here develop a new scheme of climate-vegetation regionalization with the latest demarcation outcome of HMR, the ground observation from 122 meteorological stations in HMR and its surrounding areas during 1990–2019, and the high-precision remote sensing data of land cover types. The new scheme first constructs the regionalization index system, fully considering the extraordinarily complicated geomorphic pattern of mountains and valleys, the scarcity of meteorological observations, and the remarkable differentiation of climate and vegetation in HMR. The system consists of three primary regionalization indices(i.e., days with daily average temperature steady above 10°C, aridity index, and main vegetation types, dividing the temperature zones, moisture regions, and vegetation subregions, respectively) and three auxiliary indices of the accumulated temperature above 10°C, and the temperatures in January and July. Then, the HMR is divided into five temperature zones, 20 moisture regions, and 55 vegetation subregions. Compared with previous regionalization schemes, the new scheme optimizes the climate spatial interpolation model of thin plate smoothing spline suitable for the unique terrain in HMR. Moreover, the disputed division index threshold between different climatic zones(regions) is scientifically clarifi

关键词： Climate-vegetation regionalization Thin plate smoothing spline(TPSS) GeoDetector Stepwise downscaling pane division method Hengduan Mountains Region

Multiwavelength Observations of the Infrared Dust Bubble N75 and its Surroundings

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第4期24卷 262-270页

作者： Quan-Ling cui Chuan-Peng Zhang Jun-Jie Wang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China College of Science Qiqihar UniversityQiqihar 161006China Guizhou Radio Astronomical Observatory Guizhou UniversityGuiyang 550000China

Infrared dust bubbles play an important role in the study of star formation and the evolution of the interstellar *** this work,we study the infrared dust bubble N75 and the infrared dark cloud G38.93 mainly using the tracers C^(18)O,HCO^(+),HNC and N_(2)H^(+)observed by the 30 m IRAM *** also study the targets using data from large-scale surveys:GLIMPSE,MIPSGAL,GRS,NRAO VLA Sky Survey and Bolocam Galactic Plane *** found that the C^(18)O emission is morphologically similar to the Spitzer IRAC 8.0μm ***1.1 mm cold dust emission of G38.93 shows an elongated structure from southwest to *** ionized gas from G38.93 is surrounded by polycyclic aromatic hydrocarbon emission,which may be excited by radiation from *** found that the identified young stellar objects tend to cluster around G38.93 and are mostly in class II with several class I cases distributed around N75,but no class II *** also found evidence of expanding feedback,which could have triggered star formation.

关键词： ISM:bubbles infrared:ISM galaxies:star formation

Defect-mode and Fabry-Perot resonance induced multi-band nonreciprocal thermal radiation

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第8期67卷 2405-2412页

作者： CHEN ZiHe YU ShiLv YUAN Cheng cui XinYou HU Run School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan 430074China Wuhan Fiberhome Fuhua Electric Co. Ltd.Wuhan 430074China

According to Kirchhoff's radiation law,the spectral-directional absorptivity(α)and spectral-directional emissivity(e)of an object are widely believed to be identical,which places a fundamental limit on photonic energy conversion and *** introduction of Weyl semimetals and magneto-optical(MO)materials into photonic crystals makes it possible to violate Kirchhoff's law,but most existing work only report the unequal absorptivity and emissivity spectra in a single band,which cannot meet the requirements of most practical ***,we introduce a defect layer into the structure composed of one-dimensional(1D)magnetophotonic crystal and a metal layer,which realizes dual-band nonreciprocal thermal radiation under a 3-T magnetic field with an incident angle of 60°.The realization of dual-band nonreciprocal radiation is mainly due to the Fabry-Perot(FP)resonance occurring in the defect layer and the excitation of Tamm plasmon,which is proved by calculating the magnetic field *** addition,the effects of incident angle and structural parameters on nonreciprocity are also *** is more,the number of nonreciprocal bands could be further increased by tuning the defect layer *** the defect layer thickness increases to 18.2μm,tri-band nonreciprocal thermal radiation is realized due to the enhanced number of defect modes in the photonic band gap and the FP resonance occurring in the defect ***,the effect of defect location on nonreciprocity is also *** present work provides a new way for the design of multi-band or even broad-band nonreciprocal thermal emitters.

关键词： Kirchhoff's law multi-band nonreciprocal thermal radiation magnetophotonic crystal Tamm plasmon defect layer Fabry-Perot resonance

Spatiotemporal variation of rainy season span and precipitation recorded by lacustrine laminated pollen in the Tibetan Plateau during the past two millennia

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 789-801页

作者： Anning cui Houyuan LU Juzhi HOU Xingqi LIU Deke XU Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Group of Alpine Paleoecology and Human Adaptation State Key Laboratory of Tibetan Plateau Earth SystemResources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Capital Normal University College of Resource Environment and Tourism Beijing 100048China

The quantitative reconstruction of the length of the rainy season and precipitation on the Tibetan Plateau(TP) is crucial for revealing the spatiotemporal evolution of the Westerlies and Asian summer monsoon, as well as its ecological and environmental effects. Accurately determining the start and end times of the rainy season on the Plateau remains *** study determined the start and end times of the rainy season in different locations on the Plateau by identifying precipitation inflection points. We calculated the duration and precipitation amount of the rainy season and established a transfer function between the modern pollen assemblages and them. Then, we reconstructed the rainy season variations in Kusai Lake(northern TP) and Jiang Co(central TP) during the past two millennia. The results showed that, the rainy season precipitation in Kusai Lake recorded five periods of high precipitation: AD 580–680, 1000–1100, 1200–1450, 1550–1780, and 1920–present, corresponding to the stages with long rainy season. The rainy season precipitation sequence in Jiang Co recorded four periods of high precipitation: AD 80–500, 800–950, 1250–1450, and 1780–present, which is consistent with the long rainy season before AD 1000 but unclear afterward. Spatially, rainy season precipitation on the Plateau exhibited four patterns: “wet in both north and south” may be related to abnormally strong summer monsoons;“dry in both north and south” likely associated with weak Westerly wind and weak summer monsoon;“wet in the south and dry in the north” linked to strong summer monsoon and weak Westerly wind;and “dry in the south and wet in the north” connected to weak summer monsoon and strong Westerly wind. This study revealed the spatiotemporal evolution pattern of the rainy season onset and end, duration, and precipitation amount on the Plateau over the past two millennia. It provides natural background support for further understanding the coupling between Westerly wind and Asia

关键词： Tibetan Plateau Past two millennia Rainy season length Rainy season precipitation Quantitative reconstruction