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Study on the atmospheric heat engine efficiency and heat source characteristics of the Qinghai-Tibet Plateau in summer

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Science China Earth sciences 2024年第1期67卷 117-133页

作者： Yujie LI Xiaoqing GAO Yaoming MA Zeyong HU Zhenchao LI Liwei YANG Xiao JIN Xiyin ZHOU Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions of chinese {1. of sciences Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Tianjin Key Laboratory for Oceanic Meteorology Tianjin Institute of Meteorological ScienceTianjin 300074China Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100049China University of chinese {1. of sciences Beijing 100049China

There are many types of atmospheric heat engines in land-air *** accurate definition,calculation and interpretation of the efficiency of atmospheric heat engines are key to understanding energy transfer and transformation of landair *** atmosphere over the Qinghai-Tibet Plateau(QTP)in summer can be regarded as a positive heat *** study of the heat engine efficiency is helpful to better understand land-air interaction and thermal-dynamic processes on the *** also provides a new perspective to explain the impact of the QTP on the climate of China,East Asia and even the *** this paper,we used MOD08 and ERA5 reanalysis data to calculate the atmospheric heat engine efficiency,surface heat source and atmospheric heat source on the QTP in summer(May to September)from 2000 to *** average atmospheric heat engine efficiency on the QTP in summer from 2000 to 2020 varies between 1.2%and 1.5%,which is less than 1.6%;the heat engine efficiency in summer is higher than that in June,July and August;the Qaidam Basin is the region with the highest atmospheric heat engine efficiency,followed by the western *** mean surface heat source on the QTP in summer from 2000 to 2020 is 96.0 W m^(−2),the atmospheric heat source is 90.7 W m^(−2),and the release of precipitation condensation latent heat is the most important component of the atmospheric heat source on the QTP in *** is a strong and significant positive correlation between the atmospheric heat engine efficiency and the surface heat source on the QTP in *** precipitation condensation latent heat is the most important component of the atmospheric heat source in summer and can reflect the precipitation *** is a strong and significant negative correlation between the atmospheric heat engine efficiency and the atmospheric heat source on the QTP in summer.

关键词： Qinghai-Tibet Plateau Climate change Land-air system Atmospheric heat engine Heat source on the Qinghai-Tibet Plateau

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First Record of Middle Eocene Elephant Ancestors’Footprints in the Gonjo Basin,East Tibet Plateau

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Journal of Earth Science 2024年第4期35卷 1224-1235页

作者： Asma Tahir Huazhou Yao Junaid Khan Yangui Li He Zhao Yue Yu Tang Yuan Institute of geological Survey China University of GeosciencesWuhan430074China Wuhan Center China Geological SurveyWuhan430205China State Key Laboratory of geological Processes and Mineral Resources Wuhan430078China Chengdu Center China Geological SurveyChengdu610081China Institute of Geographic sciences and Natural Resources Research Chinese Academy of SciencesBeijing100101China

It is the first time that the fossil footprints of a group of Middle Eocene elephant ancestors have been discovered in the Gonjo Basin,East Tibet *** Gonjo Formation is attributed to the Middle Eocene Epoch(U-Pb age=44.7±1.2 Ma)and consists mainly of purplish-red,medium-to coarse-grained sandstones,siltstones interbedded with mudstones,and conglomerates with sedimentary structures like ripple marks,rip-up clasts,and trough-cross bedding,suggesting fluvial-lacustrine *** group of fossil footprints has a characteristic oval-concave shape,and the toe impressions are *** fossil footprints are overstepped with a pockmarked texture resembling Proboscipeda *** than 1.5 fossil footprints of the group are relatively well-preserved with different diameters,which is evidence of highly social behavior and trackmakers of different ages,including calves,juveniles,adolescents,and *** size frequency of the fossil footprints enabled us to deduce the body mass,shoulder height,and hip-height distribution of the trackmakers that crossed the East Tibet Plateau 44.7 Ma *** trackmakers comprised an estimated average hip-height of 1.1.8 cm,an average shoulder height of 1.2.8 cm for males/1.5.9 cm for females,and an average body mass of approximately 1.1..1.kg for males/907.8 kg for *** abundance of fossil footprints reveals that in the Middle Eocene Epoch,the environment was extraordinarily conducive for the elephant ancestors to live in the East Tibet region.

关键词： Proboscipeda enigmatica East Tibet Plateau Gonjo Formation fossil footprints fluvial-lacustrine

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Improving millimeter-wave imaging quality using the vortex phase method

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Defence Technology（防务技术） 2024年第9期39卷 193-202页

作者： Nairui Hu Feng Qi Yelong Wang Zhaoyang Liu Pengxiang Liu Weifan Li Key Laboratory of Terahertz Imaging and Sensing Shenyang 110169China Shenyang Aerospace University Shenyang 110136China Key Laboratory of Opto-Electronic Information Processing Chinese Academy of SciencesShenyang 110169China Shenyang Institute of Automation Chinese Academy of SciencesShenyang 110169China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of SciencesShenyang 110169China University of chinese {1. of sciences Beijing 100049China

This paper investigates a new vortex wave imaging approach to improve the imaging quality of small metal targets of size less than 1.5 *** with different spiral phase plates are designed to efficiently transmit vortex beams with orbital angular momentums(OAMs).By analyzing the OAM spectrum of the target,it was discovered that the predominant reflection contains a particular OAM mode that carries abundant azimuthal *** can be explained by the OAM selectivity of the target and the guidance of the vortex transmitting beam.A simple reflection vortex imaging system was designed to capture the phase *** results show that the high image contrast reaches 1..9%,which is twice as high as that of the imaging without *** of simulations and experiments demonstrate that the vortex phase imaging approach proposed in this paper can effectively improve the imaging quality at 80 *** approach is suitable for other millimeter wave imaging systems and is helpful to improve the resolution in anti-terrorism security checks.

关键词： Orbital angular momentums(OAMs)beams Focal plane imaging Spiral phase plates(SPPs) Vortex spectrum

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Bunch-length measurement at a bunch-by-bunch rate based on time–frequency-domain joint analysis techniques and its application

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Nuclear Science and Techniques 2024年第4期35卷 165-175页

作者： Hong-Shuang Wang Xing Yang Yong-Bin Leng Yi-Mei Zhou Ji-Gang Wang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of chinese {1. of sciences Beijing 100049China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230026China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China

This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage *** technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous *** bunch signal is obtained using a button electrode with a bandwidth of several *** data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 1. GS/s,and the single-shot sampling data buffer covered thousands of *** bunch-length and synchronous phase information were extracted via offline calculations using Python *** calibration coefficient of the system was determined using a commercial streak ***,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1.*** dynamic range exceeded 1. *** technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.

关键词： Bunch-by-bunch diagnostic Bunch-length measurement Synchronous phase measurement Joint time–frequency-domain analysis Longitudinal instability

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Detector-integrated vertical-cavity surfaceemitting laser with a movable high-contrast grating mirror

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Photonics Research 2024年第7期12卷 1437-1448页

作者： MINGLU WANG HONGLING PENG CHENXI HAO XUYAN ZHOU WANHUA ZHENG ANJIN LIU Key Laboratory of Optoelectronic Materials and Devices Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Solid-State Optoelectronics Information Technology Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

In this paper, we present a detector-integrated vertical-cavity surface-emitting laser(VCSEL) with a movable high-contrast grating(HCG) mirror in an n-i-p-i-n manner. The detector-integrated VCSEL with a movable HCG can achieve three functions, including wavelength tuning, power monitoring, and resonant-cavity-enhanced(RCE)photon detection. Currently, the device can achieve a wavelength tuning range of 27 nm at room temperature when the suspended HCG is driven by the reverse-bias voltage. The n-i-p structure located at the upper part of the device can serve as an intra-cavity photodiode to monitor the output power due to the defect absorption. The RCE photon detection function of the detector-integrated VCSEL with a movable HCG is measured, and it has a peak responsivity at about 926 nm. This detector-integrated VCSEL with a movable HCG will be useful for sensing and imaging.

关键词： tuning laser cavity

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Uncovering the electrooxidation behavior of 5-hydroxymethylfurfural on Ni/Co electrodes

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Journal of Energy Chemistry 2024年第5期92卷 1-7页

作者： Shilin Fan Bin Zhu Xiao Yu Yang Gao Weiping Xie Yong Yang Jian Zhang Chunlin Chen Ningbo Institute of Materials Technology&Engineering Chinese Academy of SciencesNingbo 315201ZhejiangChina University of chinese {1. of sciences Beijing 100049China

Biomass,derived from plant photosynthesis that captures carbon dioxide to form carbohydrates,offers vast renewable *** electrooxidation of biomass,coupled with the hydrogen evolution reaction,enables the simultaneous production of biomass-based plastic monomers and green hydrogen,attracting significant scholarly ***,ambiguity remains regarding the adsorption mechanism at the catalyst surface(Langmuir-Hinshelwood or Eley-Rideal)and the adsorbed substrate *** address this,we prepared a Ni/Co electrode for the electrooxidation of 5-hydroxymethylfurfural(HMF)into 2,5-furandicarboxylic acid(FDCA)through a corrosion reaction and electro-reduction *** conversion reached 1.0.00%,FDCA yield reached 96.82%,and Faradic efficiency(FE)reached 92.1.%.Meaningfully,utilizing in-situ spectroscopy and electrochemical methods,this work provided valuable insights into active sites and catalyst surface adsorption.

关键词： Electrocatalysis Electrochemistry 2,5-Furandicarboxylicacid 5-Hydroxymethylfurfural Biomass

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Regional climate response to global warming in the source region of the Yellow River and its impact on runoff

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Science China Earth sciences 2024年第3期67卷 843-855页

作者： Yiran ZHANG Degang ZHOU Xiaofeng GUO Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of chinese {1. of sciences Beijing 100049China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

The source region of the Yellow River has experienced obvious climate and discharge changes in recent decades due to global warming, which largely affects the water resources and ecological and environmental security in the Yellow River basin. This study analyzed the changes in runoff and several climate factors in the source region of the Yellow River based on the observed discharges at the Tangnag hydrological station, routine meteorological data from China Meteorological Administration(CMA) stations within and near this source region, and several evaporation datasets. The results indicate that the runoff in the source region was relatively abundant from 1.60 to 1.89 and then declined sharply afterward. It recovered slightly after 2005 but was still below normal—1.% less than that during 1.60–1.89. Similarly, the precipitation amounts in the source region were relatively low in the 1.90s, but they increased significantly after 2003, with an average increase of 31.4 mm or 6% more when compared to that in 1.60–1.89. In addition, the temperatures in the source region continued to rise from 1.60 to 201., and the evaporation levels also showed an upward trend after 1.90. The influences of the spatial and temporal variations in climatic factors on runoff in the source region were then further analyzed. The results indicate that the decreases in precipitation and the number of days of heavy rainfall in the source region from 1.90 to 2002 were important reasons for the lower runoff during this period. After 2003, the precipitation in the southeastern part of the source region, which is a key area for runoff generation,increased only to a limited extent, but the evaporation in the entire source region generally increased with increasing temperature,which might have led to the low capacity for actual runoff production in each subbasin and persistent low runoff in the source region. Therefore, such a climate response to global warming in the source region might be unfavorabl

关键词： The source region of the Yellow River Climate response Runoff variation Evaporation Precipitation

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Long-term Evolution of Solar Activity and Prediction of the Following Solar Cycles

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Research in Astronomy and Astrophysics 2024年第3期24卷 194-204页

作者： Pei-Xin Luo Bao-Lin Tan National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

Solar activities have a great impact on modern high-tech systems,such as human aerospace activities,satellite communication and navigation,deep space exploration,and related scientific ***,studying the long-term evolution trend of solar activity and accurately predicting the future solar cycles are highly *** on the wavelet transform and empirical function fitting of the longest recorded data of the annual average relative sunspot number(ASN)series of 323 yr to date,this work decisively verifies the existence of the solar century cycles and confirms that its length is about 1.4.0 yr,and the magnitude has a slightly increasing trend on the timescale of several hundred *** on this long-term evolutionary trend,we predict solar cycles 25 and26 by using phase similar prediction *** for solar cycle 25,its maximum ASN will be about1.6.7±33.40,obviously stronger than solar cycle *** peak year will occur approximately in 2024,and the period will be about 1.±1.*** for solar cycle 26,it will start around 2030,and reach its maximum between2035 and 2036,with maximum ASN of about 1.3.0±3.200,and period of about 1. yr.

关键词： Sun activity-Sun evolution-(Sun) sunspots-methods data analysis

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A peak enhancement of frequency response of waveguide integrated silicon-based germanium avalanche photodetector

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Journal of Semiconductors 2024年第7期45卷 61-68页

作者： Linkai Yi Daoqun Liu Wenzheng Cheng Daimo Li Guoqi Zhou Peng Zhang Bo Tang Bin Li Wenwu Wang Yan Yang Zhihua Li Institute of Microelectronics Chinese Academy of SciencesBeijing 100029China School of Electronic Electrical and Communication Engineering University of Chinese Academy of SciencesBeijing 100049China

Avalanche photodetectors(APDs) featuring an avalanche multiplication region are vital for reaching high sensitivity and responsivity in optical transceivers. Waveguide-coupled Ge-on-Si separate absorption, charge, and multiplication(SACM)APDs are popular due to their straightforward fabrication process, low optical propagation loss, and high detection sensitivity in optical communications. This paper introduces a lateral SACM Ge-on-Si APD on a silicon-on-insulator(SOI) wafer, featuring a 1. μm-long, 0.5 μm-wide Ge layer at 1.1. nm on a standard 8-inch silicon photonics platform. The dark current measures approximately 38.6 μA at-21.V, indicating a breakdown voltage greater than-21.V for the device. The APDs exhibit a unitgain responsivity of 0.5 A/W at-1. V. At-1. V, their responsivity reaches 2.98 and 2.91.A/W with input powers of-1. and-25 dBm, respectively. The device's 3-dB bandwidth is 1. GHz with an input power of-1. dBm and a gain is 1..68. Experimental results show a peak in impedance at high bias voltages, attributed to inductor and capacitor(LC) circuit resonance, enhancing frequency response. Furthermore, 20 Gbps eye diagrams at-21.V and-9 dBm input power reveal signal to noise ratio(SNRs) of 5.30. This lateral SACM APD, compatible with the stand complementary metal oxide semiconductor(CMOS) process,shows that utilizing the peaking effect at low optical power increases bandwidth.

关键词： photodetectors optical communications responsivity 3-dB bandwidth

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Ratio of photosynthetically active radiation to global solar radiation above forest canopy in complex terrain: measurements and analyses based on Qingyuan Ker Towers

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Ecological Processes 2024年第2期13卷 204-217页

作者： Shuangtian Li Qiaoling Yan Tian Gao Xingchang Wang Qingwei Wang Fengyuan Yu Deliang Lu Huaqi Liu Jinxin Zhang Jiaojun Zhu CAS Key Laboratory of Forest Ecology and Silviculture Institute of Applied Ecology Chinese Academy of Sciences Qingyuan Forest CERN National Observation and Research Station Chinese Academy of Sciences CAS-CSI Joint Laboratory of Research and Development for Monitoring Forest Fluxes of Trace Gases and Isotope Elements Institute of Applied Ecology Chinese Academy of Sciences (CAS) University of chinese {1. of sciences Center for Ecological Research Northeast Forestry University

Background Understanding of the ratio of photosynthetic photon flux density（Qp） to global solar radiation（Rs）(Qp/Rs) is crucial for applying Rsto ecology-related *** studies reported Qp/Rsand its variations based on measurements from a single observatory tower,instead of multi-site-based measurements over complex *** may neglect spatial heterogeneity in the terrain,creating a gap in an understanding of how terrain affects Qp/Rsand how this effect interacts with meteorological *** Here the Qingyuan Ker Towers（three towers in a valley with different terrains:T1.T2,and T3） were utilized to measure Qpand Rsover mountainous forests of Northeast *** airborne LiDAR system was used to generate a digital elevation model,and sky view factor of sectors（SVFs） divided from the field of view of tower's pyranometer was calculated as a topographic factor to explain the variations of Qp/*** The results identified significant differences in Qp/Rsof the three towers at both daily and half-hour scales,with larger differences on clear days than on overcast ***/Rswas positively correlated with SVFsof T1.and T3,while this correlation was negative with that of *** effect of SVFson Qp/Rsinteracted with clearness index,water vapor pressure and solar zenith *** forest-based importance assessment demonstrated that explanation（R2） on Qp/Rswas improved when SVFswas included in the predictor variable set,indicating that incorporating terrain effects enhances the prediction accuracy of Qp/*** improvement in the R2values was more pronounced on clear days than on overcast days,suggesting that the effect of terrain on Qp/Rsdepended on sky *** All findings suggested that Qp/Rsis affected by terrain,and integrating terrain information into existing Qp/Rsmodels is a feasible solution to improve Qp/Rsestimates in mountainous areas.

关键词： Photosynthetic photon flux density Clearness index Water vapor pressure Solar zenith angle Terrain Sky view factor

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