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Green Energy & Environment 2024年第3期9卷 544-555页

作者： Hengyuan Liu Xingjiang Wu Yuhao geng Xin Li Jianhong Xu The State Key Laboratory of Chemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing100084China

Electrocatalytic nitrogen reduction reaction(NRR)is considered as a promising candidate to achieve ammonia synthesis because of clean electric energy,moderate reaction condition,safe operating process and harmless ***,the chemical inertness of nitrogen and poor activated capacity on catalyst surface usually produce low ammonia yield and faradic ***,the microfluidic technology is proposed to efficiently fabricate enriched iridium nanodots/carbon *** to in-situ co-precipitation reaction and microfluidic manipulation,the iridium nanodots/carbon nanomaterials possess small average size,uniform dispersion,high conductivity and abundant active sites,producing good proton activation and rapid electrons transmission and moderate adsorption/desorption *** a result,the as-prepared iridium nanodots/carbon nanomaterials realize large ammonia yield of 2..73 μg h^(-1) cm^(-2. and faradic efficiency of 9.14%in KOH ***,the high ammonia yield of 11.2. μg h^(-1) cm^(-2. and faradic efficiency of 2..30%are also achieved in H_(2.SO_(4) *** microfluidic method provides a reference for large-scale fabrication of nano-sized catalyst materials,which may accelerate the progress of electrocatalytic NRR in industrialization field.

关键词： Iridium nanodots Carbon Microfluidic technology Efficient synthesis Electrocatalytic nitrogen fixation

A numerical simulation on the infrared radiation of hot exhausting nozzles with a coupled flow and heat transfer model

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Science china(Technological Sciences) 2010年第10期53卷 2699-2707页

作者： hu HaiYang1 & WANG Qiang2.1 china Academy of Aerospace Aerodynamics, {2. 100074, china 2.School of Jet Propulsion, Beihang University, {2. 100191, china 1. china Academy of Aerospace Aerodynamics Beijing 100074 China2. School of Jet Propulsion Beihang University Beijing 100191 China

A coupled model among flow field,solid temperature,species concentration and gas radiation,which was based on statistical narrow-band correlated-k model,was employed to predict the infrared radiations from hot exhausting nozzles. The parameters of narrow-band model were deduced from HITEMP line-by-line database. Several methods to increase computational efficiency and to save computational resources were employed,thus all the complicated computations could be operated on a personal computer. The predictions for three cases have been conducted to validate the accuracy of the methods mentioned above,including the temperature distribution of a water-cooling nozzle in rocket engines,the carbon dioxide absorptivity at the wavelength of 4.3 micron and the infrared radiation of a cylindrical furnace. Finally,the aerothermodynamic and infrared characteristics of two nozzles were predicted. It was shown that the infrared radiation intensity of chevron ejecting nozzle were obviously smaller than that of common axisymmetric convergent-divergent nozzle.

关键词： infrared radiation numerical simulation exhausting nozzles coupled model

Prediction-based guidance algorithm for high-lift reentry vehicles

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Science china(Information Sciences) 2011年第3期54卷 498-510页

作者： ZHANG Zhao 1,2.& hu Jun 1 1 beijing Institute of Control Engineering, beijing 100190,{2. 2.Science and Technology on Space Intelligent Control Laboratory, beijing 100190,{2. 1. beijing Institute of Control Engineering Beijing 100190 China2. Science and Technology on Space Intelligent Control Laboratory Beijing 100190 China

In this work, we propose a pseudo four-degrees-of-freedom (DOF) prediction based guidance algo- rithm specifically for high-lift reentry vehicles. The algorithm is composed mainly of three parts. First, at the beginning of each guidance cycle, the 4-DOF predictor is called upon to predict the final downrange, crossrange, and heading errors. Then, the magnitude of the bank angle is determined from the downrange error, using the proportional-integral (PI) control method. Finally, two bank angle reversal time points are determined to minimize the crossrange and heading errors. Compared with traditional predictor-corrector guidance, the algorithm proposed does not require iterative procedures which significantly decreases the computational burden for the on-board computer and makes the implementation practical. Simulation results for dispersion tests demonstrated that our algorithm is computationally efficient and robust against uncertainties and disturbances.

关键词： pseudo 4-DOF prediction-based guidance high-lift reentry vehicle

Stability analysis of a hypersonic vehicle controlled by the characteristic model based adaptive controller

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Science china(Information Sciences) 2012年第10期55卷 2243-2256页

作者： ZHANG Zhao 1,2.& hu Jun 1 1 beijing Institute of Control Engineering,beijing 100190,{2. 2.Science and Technology on Space Intelligent Control Laboratory,beijing 100190,{2. 1. beijing Institute of Control Engineering Beijing 100190 China2. Science and Technology on Space Intelligent Control Laboratory Beijing 100190 China

The closed loop attitude stability of a hypersonic vehicle controlled by the characteristic model-based all-coefficient adaptive controller is studied in this paper,and an algorithm based on the computation of induced matrix 1-norm or ∞-norm is *** of all,the Taylor series expansion is applied to discretize the inputoutput description of the attitude dynamics of the *** obtained difference equations have the same structure as characteristic model;thus the intervals which contain all possible values of certain characteristic model parameters are *** the linear feedback controller is used in the feedback loop,with some conservation,the closed loop system is viewed as a class of interval time-varying systems defined by a number of free time-varying *** free parameters take values from predefined *** sufficient and necessary condition for the stability of this class of system is ***,a sufficient condition for the stability of hypersonic vehicle attitude control loop is proposed and demonstration example is *** method proposed checks up the stability of the closed loop system by evaluating a finite number of matrix norms,and overcomes the difficulties brought by the time-varying nature of the characteristic model and parameter estimation.

关键词： characteristic model hypersonic vehicle interval time-varying system stability test attitude control

On the placement of actuators and sensors for flexible structures with closely spaced modes

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Science china(Technological Sciences) 2010年第7期53卷 1973-1982页

作者： LIU XiaoXiang1,2.& hu Jun1,2.1 beijing Institute of Control Engineering, beijing 100190,{2. 2.State Key Laboratory of Science and Technology on Space Intelligent Control, beijing 100190,{2. 1. beijing Institute of Control Engineering Beijing 100190 China2. State Key Laboratory of Science and Technology on Space Intelligent Control Beijing 100190 China

This paper analyzed the fundamental limitations of previous work and developed a new method to optimally locate actuators and sensors for structures with close modes. Optimization criteria were defined based on the distinguishing modal controllability and observability measures of close modes. An appropriate genetic algorism was adopted as the optimization algorism. Solving the high order Lyapunov functions was avoided by means of the closed-form expressions for controllability and observability Grammians. Since structure with widely separated natural frequencies is approximately balanced, computational efficiency was improved by grouping close modes together and dealing with the resulting subsystems independently. Finally, the effectiveness and optimality of the novel placement scheme were verified on a model structure with close modes.

关键词： close modes controllability/observability sensor/actuator optimization criterion optimization algorithm

SHRIMP zircon U-Pb age and Nd isotopic study on the Nyainqêntanglha Group in Tibet

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Science china Earth Sciences 2005年第9期48卷 1377-1386页

作者： hu Daogong1, WU Zhenhan1, JIANG Wan1, SHI Yuruo2. YE Peisheng1 & LIU Qisheng1 1. Institute of Geomechanics, Chinese Academy of Geological Sciences, beijing 100081,{2. 2. Institute of Geology, Chinese Academy of Geological Sciences, beijing SHRIMP Centre, beijing 100037,{2. 1. Institute of Geomechanics Chinese Academy of Geological Sciences 100081 Beijing China 2. Institute of Geology Chinese Academy of Geological Sciences Beijing SHRIMP Centre 100037 Beijing China

The Nyainqêntanglha Group is traditionally viewed as the oldest metamorphic basement in the Lhasa block, but its formation age and tectonic setting remain debate. Zircons extracted from the metamorphic sequence of volcanics and intrusions of the Nyainqêntanglha Group, 10 km west of Nam Co in northern Lhasa block, have been investigated by cathodolu- minescence (CL), backscattered (BSE) and dated by ion microprobe (SHRIMP). We conclude that the U-Pb age of 787±9 Ma of zircons from the trondhjemite imposes a constraint on maxi- mum protolith age, and minimum formation age of the Nyainqêntanglha Group is constrained by U-Pb age of 748±8 Ma of zircons from the granite. The formation age of the Nyainqêntanglha Group is consistent with sedimentary age of Greater Himalayan rocks, showing that they devel- oped coevally in an arc-basin tectonic setting of Neoproterozoic active continental margin along the northern margin of the India shield. The inherited zircons from the tholetiite and granite give older 2.7Pb/2.6Pb ages from 947 to 1766 Ma. The positive εNd( t ) value indicates that the mafic rocks were derived from the depleted mantle, but contaminated by the older continental crustal material. Integrated Nd model age and U-Pb age data provide excellent evidence for the exis- tence of Mesoproterozoic basement in the Lhasa block during Neoproterozoic time.

关键词： Nyainqêntanglha Group, SHRIMP dating, Nd isotope, Neoproterozoic, Tibet.

Droplet creator based on electrowetting-on-dielectric for lab on a chip

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Science china(Technological Sciences) 2006年第2期49卷 248-256页

作者： ZENG Xuefeng1, YUE Ruifeng1, WU Jiangang1, hu huan1, DONG Liang1, WANG Zheyao1, HE Feng2.& LIU Litian1 1. Institute of Microelectronics, Tsinghua University, beijing 100084, china 2. Department of Engineering Mechanics, Tsinghua University, beijing 100084, china 1. Institute of Microelectronics Tsinghua University Beijing 100084 China 2. Department of Engineering Mechanics Tsinghua University Beijing 100084 China

Electrowetting-on-dielectric (EWOD) is to directly control the wettability of liquids on the solid surface by applying the electric potential to the microelectrode array under the dielectric layer. The prototype of the EWOD droplet creator with the sandwiched structure is used: the droplet is sandwiched between the top and bottom plates; the bot- tom plate consists of silicon used as the substrate of the microelectrode array, nitride sili- con film deposited by low pressure chemical vapor deposition as the dielectric layer and the fluorocarbon polymer film deposited by inductively coupled plasma chemical vapor deposition as the hydrophobic layer; and the top plate is the transparent electrode covered with the hydrophobic layer. To obtain the required minimum voltage, the process and the criterion of creating droplets are analyzed. At the voltage of 35 V the deionized water droplet surrounded in silicone oil is successfully created.

关键词： micro total analysis system, electrowetting-on-dielectric, creation and control of droplets, inductively coupled plasma chemical vapor deposition.

Probing signals of atmospheric gravity waves excited by the July 2.,2.2. M_(W)8.2.Alaska earthquake

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Geodesy and Geodynamics 2024年第3期15卷 219-229页

作者： geng Zhang Jianqiao Xu Xiaodong Chen Heping Sun Lizhuo Gong State Key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430077China University of Chinese Academy of Sciences Beijing100049China

It is commonly believed that the atmosphere is decoupled from the solid ***,it is difficult for the seismic wave energy inside the Earth to propagate into the atmosphere,and atmospheric pressure wave signals excited by earthquakes are unlikely to exist in atmospheric *** increasing number of studies have shown that earthquakes,volcanoes,and tsunamis can perturb the Earth's atmosphere due to various coupling ***,the observations mainly focus on acoustic waves with periods of less than 10 min and inertial gravity waves with periods of greater than 1 *** are almost no clear observations of gravity waves that coincide with observations of low-frequency signals of the Earth's free oscillation frequency band within 1 *** paper investigates atmospheric gravity wave signals within1 h of surface-atmosphere observations using the periodogram method based on seismometer and microbarometer observations from the global seismic network before and after the July 2.,2.2. M_(w)8.2.Alaska earthquake in the United *** numerical results show that the atmospheric gravity wave signals with frequencies similar to those of the Earth's free oscillations _(0)S_(2. and _(0)T_(2. can be detected in the microbaro meter *** results con firm the existence of atmospheric gravity waves,indicating that the atmosphere and the solid Earth are not decoupled within this frequency band and that seismic wave energy excited by earthquakes can propagate from the interior of the Earth to the atmosphere and enhance the atmospheric gravity wave signals within 1 h.

关键词： Atmospheric gravity modes Atmospheric gravity waves Alaska earthquake Normal modes Coupling of solid earth and atmosphere

Isotopic feature and uranium dating of the volcanic rocks in the Okinawa Trough

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中国科学：地球科学英文版 2006年第4期49卷 375-383页

作者： huANG Peng1,2. LI Anchun1, hu Ningjing2.3, FU Yongtao1& MA Zhibang4 1. Institute of Oceanology, Chinese Academy of Sciences, Qingdao 2.6071, china 2. Graduate School of the Chinese Academy of Sciences,{2., china 3. Institute of Soil Science, Chinese Academy of Sciences, Nanjing 2.0008, china 4. Institute of Geology and Geophysics, Chinese Academy of Sciences, beijing 10002., china 1. Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China 2. Graduate School of the Chinese Academy of Sciences Beijing 100039 China 3. Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China 4. Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Volcanic rocks from the northern and middle Okinawa Trough were dated by ura- nium-series dating method. Differential fractions using magnetic procedure were designed to separate samples. New report on the ages and isotopic data of rocks in the northern trough (especially black pumice) was discussed. Based on the uranium dates and Sr-Nd isotopic ratio, magmatic evolution process of the Okinawa Trough was noted. Firstly, there have been wide silicic volcanic activities in the Okinawa Trough from late Pleistocene to present, and the volcanic rocks can be divided into three subgroups. Secondly, magma generally came from PREMA source area under the Okinawa Trough. Magmatic evolution in the northern trough was similar to the middle, but different to the south. Finally, volcanic activities indicated that opening of the southern Okinawa Trough did not happen due to the collision between Luson Arc and Eurasian Plate until the early Pleistocene.

关键词： Okinawa Trough, black pumice, uranium-series dating, Sr-Nd isotopic ratio, magmatic evolution.

High-performance Ti_(3)C_(2.T_(x)achieved by polyaniline intercalation and gelatinization as a high-energy cathode for zinc-ion capacitor

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Nano Research 2024年第6期17卷 5305-5316页

作者： Peng Liao ZiYu geng Xin Zhang Wenjie Yan Zenghui Qiu Haijun Xu College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China

The actual manufacture of supercapacitors(SCs)is restricted by the inadequate energy density,and the energy density of devices can be properly promoted by assembling zinc-ion capacitors(ZICs)which used capacitive cathode and battery-type ***-dimensional(2.)MXene has brought great focuses in the electrode research on the foundation of large redox-active surface,but the specific capacitance is still affected by the tight stacking of ***_(3)C_(2.T_(x)@polyaniline(PANI)heterostructures are prepared by uniformly depositing the conductive polymer PANI nanorods as the intercalation agent into the external of Ti_(3)C_(2.T_(x)nanosheets to inhibit ***,by using graphene oxide(GO)-assisted low-temperature hydrothermal self-assembly manufacture,2. heterostructures are assembled into the three-dimensional(3D)porous crosslinked Ti_(3)C_(2.T_(x)@PANI-reduced graphene oxide(RGO)*** to the synergistic work of PANI nanorods,Ti_(3)C_(2.T_(X)nanosheets,and 3D crosslinking frameworks of RGO to match capacitive and battery effects,3D porous hierarchical Ti_(3)C_(2.T_(x)@PANI-RGO heterostructure hydrogels have rich ion transport channels,a large number of active sites,and excellent reaction *** is assembled by using Ti_(3)C_(2.T_(x)@PANI-RGO heterostructure hydrogels as cathodes and zinc foil as *** this work,Ti_(3)C_(2.T_(x)@PANI-RGO//Zn ZIC exhibits a wide working window(2.0 V),marked specific capacitance(589.89 F·g^(−1)at 0.5 A·g−1),salient energy density(32..71 Wh·kg^(−1)at 513.61 W·kg^(−1)and 192.2. Wh·kg^(−1)at 13,005.87 W·kg^(−1)),and durable cycling stability(97.87%capacitance retention after 10,000 cycles at 10 A·g^(−1)).This study emphasizes the device design of ZICs and the broad prospect of Ti_(3)C_(2.T_(x)-based hydrogels as viable cathodes for ZICs.

关键词： polyaniline(PANI) Ti_(3)C_(2.T_(x)@PANI heterostructure intercalation process three-dimensional(3D)porous hydrogel high energy density zinc-ion capacitor