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Carbon nanotube network film-based ring oscillators with sub l O-ns propagation time and their applications in radio-frequency signal transmission

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Nano Research 2018年第1期11卷 300-310页

作者： Yingjun Yang Li Ding Hengjia Chen Jie Han Zhiyong Zhang Lian-Mao Peng key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics Peking University Beijing 100871 China

We have fabricated top-gated ambipolar field-effect transistors （FETs） based on solution-derived carbon nanotube （CNT） network films, and then constructed inverters and ring oscillators （ROs） that can work under supply voltages as low as 0.2 V owing to the high uniformity of the devices. Significant improvements were achieved in the performance of these CNT-based ambipolar FETs and CMOS-like circuits by scaling down the gate length of the CNT FETs and optimizing the device structure and RO layout. In particular, the optimized five-stage RO is shown to present a record high oscillation frequency of up to 17.4 MHz with a propagation time of 5.6 ns at a 12-V working voltage. The CNT film-based ROs were used as carrier-wave generators in radio-frequency systems to demonstrate a complete signal transmission process. These results suggest that CNT thin film-based FETs and integrated circuits may soon find their way to radio-frequency applications with a frequency band of 13.56 MHz.

关键词： carbon nanotube nanoelectronics field-effect transistors radio-frequency ring oscillator

All-fiberized very-large-mode-area Yb-doped fiber based high-peak-power narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate

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Chinese Physics B 2020年第11期29卷 343-349页

作者： Min Yang Ping-Xue Li Dong-Sheng Wang Ke-Xin Yu Xue-Yan Dong Ting-Ting Wang Chuan-Fei Yao Wei-Xin Yang Institute of Laser Engineering Beijing University of TechnologyBeijing 100124China

We demonstrate an all-fiberized narrow-linewidth nanosecond amplifier with high peak power,tunable pulse width,and repetition rate.A fiber-coupled narrow-linewidth laser diode operating at 1064.1 nm is employed as the seed source,which is gain-switched to generate nanosecond pulses with tunable pulse widths of 1-200 ns and tunable repetition rates of10 Hz-100 *** utilizing a very-large-mode-area Yb-doped fiber with a core diameter of 50 μm in the power amplifier,thresholds of the stimulated Brillouin scattering at different pulse widths and repetition rates are *** maximum average power reaches 30.8 W at the pulse width of 4 ns and a repetition rate of 100 kHz,corresponding to an optical-tooptical conversion efficiency of ~55.2%.Pulse energy and peak power are calculated to be 0.2 mJ and 50 kW,respectively,which are limited by stimulated Brillouin *** 3-dB spectral linewidth remains around 0.05 nm during the power scaling *** stimulated Brillouin scattering limited output powers at different pulse widths and repetition rates are *** power of 47.5 kW(0.19 mJ) is obtained for the 4 ns pulses at a repetition rate of 50 kHz,which is nearly the same as that of 4 ns pulses at 100 *** the pulse width of the seed source is increased to 8 ns,peak powers/pulse energies are decreased to 19.6 kW/0.11 mJ and 13.3 kW/0.08 mJ at repetition rates of 50 kHz and 100 kHz,respectively.

关键词： nanosecond all-fiber amplifier very-large mode area tunable pulse width and repetition rate

A modified active disturbance rejection control for a wastewater treatment process

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Chinese Journal of Chemical Engineering 2020年第10期28卷 2607-2619页

作者： Wei Wei Pengfei Xia Zaiwen Liu Min Zuo beijing Technology and Business University Beijing 100048China National Engineering Laboratory for Agri-product Quality TraceabilityBeijing Technology and Business UniversityBeijing 100048China Beijing Key Laboratory of Big Data Technology for Food SafetyBeijing 100048China

Waste water treatment process(WWTP)control has been attracting more and more ***,various undesired factors,such as disturbance,uncertainties,and strong nonlinear couplings,propose big challenges to the control of a *** order to improve the control performance of the closed-loop system and guarantee the discharge requirements of the effluent quality,rather than take the model dependent control approaches,an active disturbance rejection control(ADRC)is *** on the control signal and system output,a phase optimized ADRC(POADRC)is designed to control the dissolved oxygen and nitrate concentration in a *** phase advantage of the phase optimized extended state observer(POESO),convergence of the POESO,and stability of the closed-loop system are analyzed from the theoretical point of ***,a commonly accepted benchmark simulation model no.1.(BSM1)is utilized to test the POESO and *** active disturbance rejection control(LADRC)and the suggested proportion-integration(PI)control are taken to make a comparative *** system responses and performance index values confirm the advantage of the POADRC over the LADRC and the suggested PI *** results show that,as a result of the leading phase of the total disturbance estimation,the POESO based POADRC is an effective and promising way to control the dissolved oxygen and nitrate concentration so as to ensure the effluent quality of a WWTP.

关键词： Wastewater treatment process BSM1 Dissolved oxygen Nitrate concentration Active disturbance rejection control Phase optimization extended state observer

Analyzing the spatiotemporal evolution and driving forces of gross ecosystem product in the upper reaches of the Chaobai River Basin

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Frontiers of Environmental Science & Engineering 2024年第8期18卷 117-132页

作者： Jiacheng Li Qi Han Liqiu Zhang Li Feng Guihuan Liu beijing key Laboratory for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China Engineering Research Center for Water Pollution Source Control&Eco-remediation College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China Center of Eco-compensation Chinese Academy of Environmental PlanningMinistry of Ecology of EnvironmentBeijing 100041China

The Chaobai River Basin,which is a crucial ecological barrier and primary water source area within the beijing-Tianjin-Hebei region,possesses substantial ecological *** gross ecosystem product(GEP)in the Chaobai River Basin is a reflection of ecosystem conditions and quantifies nature’s contributions to humanity,which provides a basis for basin ecosystem service management and *** study investigated the spatiotemporal evolution of GEP in the upper Chaobai River Basin and explored the driving factors influencing GEP spatial *** patterns from 2005 to 2020 were analyzed,and GEP was calculated for 2005,2010,2015,and *** driving factors influencing GEP spatial differentiation were identified using the optimal parameter-based geographical detector(OPGD)*** key findings are as follows:(1)From 2005 to 2020,the main ecosystem types were forest,grassland,and *** areas experienced significant changes,and conversions mainly occurred among urban,water,grassland and agricultural ecosystems.(2)Temporally,the GEP in the basin increased from 2005 to 2020,with regulation services *** the county(district)scale,GEP exhibited a north-west-high and south-east-low pattern,showing spatial differences between per-unit-area GEP and county(district)GEP,while the spatial variations in per capita GEP and county(district)GEP were similar.(3)Differences in the spatial distribution of GEP were influenced by regional natural geographical and socioeconomic *** these factors,gross domestic product,population density,and land-use degree density contributed *** among different driving forces noticeably impacted GEP spatial *** findings underscore the necessity of incorporating factors such as population density and the intensity of land-use development into ecosystem management decision-making processes in the upper reaches of the Chaobai River *** policies

关键词： Ecosystem pattern Gross ecosystem product(GEP) Spatiotemporal evolution Optimal parameter-based geographical detector(OPGD) Chaobai River Basin

Long-Term Outcome of A Large Series of Gastric Cancer Patients in China

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Chinese Journal of Cancer Research 2010年第3期22卷 167-175页

作者： Ai-wen Wu Jia-fu Ji Hong Yang Yan-ning Li Shuang-xi Li Lian-hai Zhang Zi-yu Li Xiao-jiang Wu Xiang-long Zong Zhao-de Bu Ji Zhang Xiang-qian Su Yi Wang Guang-wei Xu key Laboratory of Carcinogenesis and Translational Research （Ministry of Education） Department ofGastrointestinal Surgery Peking University School of Oncology Beijing Cancer Hospital ＆ Institute Beijing100142 China

Objective：The outcome of gastric cancer treatment in China is relatively poor compared with those in Japan and *** factors are not quite clear till *** aim of this study is to present data on gastric cancer patients from a single high volume cancer center of China and to illuminate relevant factors regarding unsatisfactory ***：A total of 2312 consecutive pathologically proven gastric carcinoma patients were treated in beijing Cancer Hospital from January 1995 to December *** information including demographic information,tumor characteristics,therapeutic experience and survival was retrieved from the Database specially designed for Gastric Cancer Collaborative Group,beijing Cancer ***：There were 1633 males and 679 females with a median age of 58.8 years（range 19-89）.Merely 181 patients were in the early stage（7.8%）.Curative resection was performed in less than 72% of the *** number of lymph nodes harvested varied from 0 to 71（average 9） while the median number of positive lymph node was 2（0-37）.Only in 650 patients the number of lymph nodes harvested was more than *** the end of follow-up,874 patients were still alive while 1132 *** 1,2,5,10-year overall survival were 68.50%,51.88%,36.83%,and 30.49%,*** analysis demonstrated that TNM stage,tumor location,tumor size,surgery,and vascular invasion were independent prognostic ***：The outcome of gastric cancer in China is not as good as *** detection and standardized curative resection should be prompted at present to improve the outcome.

关键词： Gastric cancer Management Outcome

Preferred search over encrypted data

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Frontiers of Computer Science 2018年第3期12卷 593-607页

作者： Zhirong SHEN Jiwu SHU Wei XUE Department of Computer Science and Technology Tsinghua University Beijing 100084 China

Cloud computing provides elastic data storage and processing services. Although existing research has proposed preferred search on the plaintext files and encrypted search, no method has been proposed that integrates the two techniques to efficiently conduct preferred and privacypreserving search over large datasets in the cloud. In this paper, we propose a scheme for preferred search over encrypted data （PSED） that can take users＇ search preferences into the search over encrypted data. In the search process, we ensure the confidentiality of not only keywords but also quantified preferences associated with them. PSED constructs its encrypted search index using Lagrange coefficients and employs secure inner-product calculation for both search and relevance measurement. The dynamic and scalable property of cloud computing is also considered in PSED. A series of experiments have been conducted to demonstrate the efficiency of the proposed scheme when deploying it in realworld scenarios.

关键词： preferred search encrypted data secure innerproduct calculation

Formation mechanism of hydride precipitation in commercially pure titanium

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Journal of Materials Science & Technology 2021年第22期81卷 108-116页

作者： Jingwei Li Xiaocui Li Manling Sui beijing key Laboratory of Microstructure and Properties of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing100124China Department of Mechanical Engineering City University of Hong KongHong Kong999077China

Since titanium has high afﬁnity for hydrogen and reacts reversibly with hydrogen,the precipitation of titanium hydrides in titanium and its alloys cannot be *** most common hydride precipitates in α-Ti matrix areγ-hydride and δ-hydride,however their mechanisms for precipitation are still *** the present study,we find that both γ-hydride and δ-hydride phases with different specific orientations were randomly precipitated in the as-received hot forged commercially pure *** addition,a large amount of the titanium hydrides can be introduced into Ti matrix with selective precipitation by using electrochemical ***-corrected scanning transmission electron microscopy is used to study the precipitation mechanisms of the two *** is revealed that the γ-hydride and δ-hydride precipitations are both formed through slip+shuffle mechanisms involving a unit of two layers of titanium atoms,but the difference is that the γ-hydride is formed by prismatic slip corresponding to hydrogen occupying the octahedral sites of α-Ti,while the δ-hydride is formed by basal slip corresponding to hydrogen occupying the tetrahedral sites ofα-Ti.

关键词： Pure titanium Titanium hydride Precipitation mechanism Slip Shuffle

Enigmatic earwig-like fossils from Inner Mongolia, China

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Insect Science 2010年第5期17卷 459-464页

作者： Jing-Xia Zhao Dong Ren Chungkun Shih College of Life Science Capital Normal University Beijing China

A new species of a new genus, Atopderma ellipta gen. et sp. nov. is described from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. Because of poor preservation, the placement of these specimens is contentious, either Dermaptera or Coleoptera. However, we are inclined to attribute them to Dermaptera based on differences of five key characters. Detailed description and illustration of the specimens are given. Possible reasons for lacking good and complete abdomen preservation are also discussed.

关键词： Dermaptera Daohugou earwig-like fossil Middle Jurassic

A review on thermal conductivity of magnesium and its alloys

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Journal of Magnesium and Alloys 2020年第1期8卷 78-90页

作者： Shubo Li Xinyu Yang Jiangtao Hou Wenbo Du College of Materials Science and Engineering Beijing University of TechnologyBeijing 100124P.R.China

This review summarizes recent researching works the thermal conductivity of Mg–Zn,Mg–Al,Mg–Mn and Mg–RE *** atoms,heat treatment,deformation and temperature,which have significant influence on the thermal conductivity of magnesium alloys,are *** an individual solute atom,its effects on thermal conductivity are highly dependent on its chemical valence,radius and extra-nuclear *** thermal conductivity of Mg alloys is decreased by solution treatment,but improved by aging and/or annealing *** for the deformed Mg alloys,the thermal conductivity along transverse or normal direction is superior to that of along extrusion or rolling *** expect this review is helpful for those who are working on developing Mg alloys with superior thermal conductivity.©2020 Published by Elsevier *** behalf of Chongqing University.

关键词： Magnesium alloys Thermal conductivity Microstructure Influencing factors