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Acta Mechanica Sinica 2010年第4期26卷 509-520页

作者： yan-Lai Zhang mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Institute of Fluid Mechanics Beihang University 100191 Beijing China

In the present paper, the longitudinal dynamic flight stability properties of two model insects are predicted by an approximate theory and computed by numerical sim- ulation. The theory is based on the averaged model （which assumes that the frequency of wingbeat is sufficiently higher than that of the body motion, so that the flapping wings＇ degrees of freedom relative to the body can be dropped and the wings can be replaced by wingbeat-cycle-average forces and moments）; the simulation solves the complete equations of motion coupled with the Navier-Stokes equations. Comparison between the theory and the simulation provides a test to the validity of the assumptions in the theory. One of the insects is a model dronefly which has relatively high wingbeat frequency （164 Hz） and the other is a model hawkmoth which has relatively low wingbeat frequency （26 Hz）. The results show that the averaged model is valid for the hawkmoth as well as for the dronefly. Since the wingbeat frequency of the hawkmoth is relatively low （the characteristic times of the natural modes of motion of the body divided by wingbeat period are relatively large） compared with many other insects, that the theory based on the averaged model is valid for the hawkmoth means that it could be valid for many insects.

关键词： Insect Hovering Dynamic flight stability Averaged model Equations-of-motion Navier-Stokes simulation

Dimensionless study on outlet flow characteristics of an air-driven booster

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第6期13卷 481-490页

作者： yan SHI mao-lin CAI School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

Air-driven boosters are widely used to obtain high-pressure gas. Through analysis of the boosting process of an air-driven booster, the basic mathematical model of working processes can be set up. By selecting the appropriate reference values, the basic mathematical model is transformed to a dimensionless expression. Using MATLAB/Simulink for simulation and studying the booster experimentally, the dimensionless outlet flow characteristics of the booster were obtained and the simulation results agree well with the experimental results. Through analysis, it can be seen that the dimensionless outlet flow of the booster is mainly determined by the dimensionless input pressure of the driving chamber, the dimensionless outlet condition pressure of the booster and the dimensionless area of the piston in the driving chamber. The dimensionless average outlet flow becomes larger with an increasing dimensionless input pressure of the driving chamber, but it becomes smaller with an increase in the dimen- sionless outlet condition pressure of the booster. Especially when the dimensionless outlet condition pressure is approximately 1.4, the dimensionless average outlet flow reaches zero. With an increase in the dimensionless area of the piston in the driving chamber, the dimensionless average outlet flow increases and peaks at approximately 1.89, and after this peak, it starts to decrease. This research can be referred to in the design of air-driven boosters.

关键词： Air-driven booster Outlet flow Pneumatic system Compressed air

Stabilization control of a hovering model insect:lateral motion

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Acta Mechanica Sinica 2011年第5期27卷 823-832页

作者： yan-Lai Zhang mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beihang University 100191 Beijing China

Our previous study shows that the lateral disturbance motion of a model drone fly does not have inherent stability （passive stability）,because of the existence of an unstable divergence *** drone flies are observed to fly *** active control must be applied to stabilize the *** this study,we investigate the lateral stabilization control of the model drone *** method of computational fluid dynamics is used to compute the lateral control derivatives and the techniques of eigenvalue and eigenvector analysis and modal decomposition are used for solving the equations of *** analysis shows that although inherently unstable,the lateral disturbance motion is *** feeding back the state variables （*** translation velocity,yaw rate,roll rate and roll angle,which can be measured by the sensory system of the insect） to produce anti-symmetrical changes in stroke amplitude and/or in angle of attack between the left and right wings,the motion can be stabilized,explaining why the drone flies can fly stably even if the flight is passively unstable.

关键词： Hovering drone fly Lateral motion Flight stability Stabilization control Modal analysis

Leaching isomorphism rare earths from phosphorite ore by sulfuric acid and phosphoric acid

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Rare Metals 2017年第10期36卷 840-850页

作者： Hui-Xin Jin Fu-Zhong Wu xiao-Hao mao Mei-Long Wang Hong-yan Xie College of Materials and Metallurgy Guizhou University Guiyang 550025 China Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025 China

Most of the phosphorite deposits in the world contain isomorphism rare earths （RE） which are considerably difficult to be leached into solution in the wet phos- phoric acid process. In this work, a systematic study of leaching RE using sulfuric acid, phosphoric acid, mixed acid and two-step leaching of phosphoric acid and sulfuric acid was performed. The aims are to illuminate the main factors that inhibit RE leaching and to provide insights into the further enrichment of RE in the wet phosphoric acid solution. The results indicate that H2SO4 is not an effective acid for leaching isomorphism RE from phosphorite ore. The low RE leaching efficiency attributes to the RE cocrystallized and encapsulated by phosphogypsum （PG） as well as the precipitation of RE by RE sulfates or phosphates. High concentration of H3PO4 can enhance the dissolution and diffusion of RE ions. Hence, the optimized leaching mode of improving RE leaching efficiency is to adequately dissolve phosphorite ores in high concentration of H3PO4 solution and then add H2SO4 to crystallize PG. The effect of corystallization or encapsulation of PG on RE can be decreased due to the crystallizing mode of PG in the bulk solution instead of on the interface of solid reactants. RE leaching efficiency can be high up to 65% by the optimized leaching mode.

关键词： Phosphorite Isomorphism Rare earths Leaching Sulfuric acid Phosphoric acid

Clinical value of liver and spleen shear wave velocity in predicting the prognosis of patients with portal hypertension

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World Journal of Gastroenterology 2017年第45期23卷 8044-8052页

作者： yan Zhang Da-Feng mao Mei-Wu Zhang xiao-Xiang Fan Department of Interventional Therapy Second Hospital of Ningbo Municipality

AIM To explore the relationship of liver and spleen shear wave velocity in patients with liver cirrhosis combined with portal hypertension,and assess the value of liver and spleen shear wave velocity in predicting the prognosis of patients with portal *** All 67 patients with liver cirrhosis diagnosed as portal hypertension by hepatic venous pressure gradient in our hospital from June 2014 to December 2014 were enrolled into this study. The baseline information of these patients was recorded. Furthermore,67 patients were followed-up at 20 mo after treatment,and liver and spleen shear wave velocity were measured by acoustic radiation force impulse at the 1^(st) week,3^(rd) month and 9^(th) month after treatment. Patients with favorable prognosis were assigned into the favorable prognosis group,while patients with unfavorable prognosis were assigned into the unfavorable prognosis group. The variation and difference in liver and spleen shear wave velocity in these two groups were analyzed by repeated measurement analysis of variance. Meanwhile,in order to evaluate the effect of liver and spleen shear wave velocity on the prognosis of patients with portal hypertension,Cox's proportional hazard regression model analysis was applied. The ability of those factors in predicting the prognosis of patients with portal hypertension was calculated through receiver operating characteristic(ROC) *** The liver and spleen shear wave velocity in the favorable prognosis group revealed a clear decline,while those in the unfavorable prognosis group revealed an increasing tendency at different time points. Furthermore,liver and spleen shear wave velocity was higher in the unfavorable prognosis group,compared with the favorable prognosis group; the differences were statistically significant(P < 0.05). The prognosis of patients with portal hypertension was significantly affected by spleen hardness at the 3^(rd) month after treatment [relative risk(RR) = 3.481].

关键词： Liver cirrhosis Portal hypertension Liver and spleen shear wave velocity Acoustic radiation force impulse

Preparation of Al2O3–SiO2 composite aerogels and their Cu2+absorption properties

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International Journal of Minerals,Metallurgy and Materials 2021年第2期28卷 317-324页

作者： xiao-guang Liu Qiu-shuo mao Yue Jiang yan Li Jia-lin Sun Fei-xue Huang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Fundamental Experimental Centre of Nature Science University of Science and Technology BeijingBeijing 100083China

In order to remediate heavy metal ions from waste water,Al2O3–SiO2 composite aerogels are prepared via a sol–gel and an organic solvent sublimation drying *** characterisation techniques have been employed including X-ray diffraction(XRD),Fourier transform infrared spectrometry(FTIR),scanning electron microscope(SEM),Energy-dispersion X-ray spectroscopy(EDX),Brunauer–Emmett–Teller(BET)N2 adsoprtion isotherm,and atomic absorption spectrometer(AAS).XRD and FTIR suggest that the aerogels are composed of mainly Al2O3 and minor *** have a high specific surface area(827.544 m^2/g)and high porosity(86.0%)with a pore diameter of~20 *** microstructures show that the distribution of Al,Si,and O is *** aerogels can remove~99%Cu^2+within~40 min and then reach the equilibrium uptake(~69 mg/g).Preliminary calculations show that the Cu2+uptake by the aerogels follows pseudo second-order kinetics where chemical sorption may take effect owing largely to the high surface area,high porosity,and abundant functional groups,such as Al–OH and Si–OH,in the aerogel *** prepared aerogels may serve as efficient absorbents for Cu^2+removal.

关键词： heavy metal ion aerogel absorption organic solvent sublimation drying specific surface area porosity

A 2 Gb/s optical receiver with monolithically integrated MSM photodetector in standard CMOS process

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Chinese Science Bulletin 2011年第21期56卷 2281-2285页

作者： xiao XinDong ZHANG ShiLin mao LuHong XIE Sheng CHEN yan School of Electronic Information Engineering Tianjin UniversityTianjin 300072China

A monolithically standard complementary-metal-oxide-semiconductor (CMOS) optical receiver with a metal-semiconductor-metal (MSM) photodetector is presented in this *** active-feedback transimpedance amplifier (TIA) with negative Miller capacitance is used to increase the bandwidth of the *** MSM photodetector with high responsivity provides higher sensitivity for the optical *** optical receiver implemented in chartered 0.35 μm process achieves a 1.7 GHz bandwidth due to the low capacitance of the MSM photodetector.2 Gb/s optical data are successfully transmitted with a bit-error rate of 10-9 at an optical power of-15 *** power consumption of the receiver is 94 mW under a single 3.3 V supply.

关键词： MSM光探测器 CMOS工艺光接收器光电探测器单片集成互补金属氧化物半导体 Gb 标准

Deep Learning Based Channel Estimation in Fog Radio Access Networks

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China Communications 2019年第11期16卷 16-28页

作者： Zhendong mao Shi yan State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

As a promising paradigm of the fifth generation networks,fog radio access network(F-RAN)has attracted lots of attention *** fully utilize the promising gain of F-RANs,the acquisition of accurate channel state information is ***,conventional channel estimation approaches are not suitable in F-RANs due to the large training and feedback *** this paper,we consider the channel estimation in F-RANs with fog access point(F-AP)equipped with massive *** to the computing ability of F-AP and the sparsity of channel matrices in angular domain,Gated Recurrent Unit(GRU),a data-driven based channel estimation is proposed at F-AP to reduce the training and feedback *** GRU-based method can capture the hidden sparsity structure automatically through the network ***,to further improve the channel estimation,a bidirectional GRU based method is proposed,whose target channel structure is decided by previous and subsequent *** compare the performance of our proposed channel estimation with traditional methods(Orthogonal Matching Pursuit(OMP)and Simultaneous OMP(SOMP)).Simulation results show that the proposed approaches have better performance compared with the traditional OMP and SOMP methods.

关键词： fog radio access network(F-RAN) massive MIMO compressive sensing deep learning gated recurrent unit(GRU)

Transcript and Sequence Analysis of S-RNases in Self-Compatible Tetraploid Chinese Cherry (Prunus pseudocerasus L.)

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Agricultural Sciences in China 2010年第6期9卷 792-798页

作者： ZHANG xiao-yan CHEN Xue-sen MENG Qing-wei JIANG Yuan-mao ZHENG yang CHEN xiao-liu Institute of Horticulture Science and Engineering/State Key Laboratory of Crop Biology Shandong Agricultural University Tai＇an 271018 P.R.China Life Science Shandong Agricultural University Tai＇an 271018 PR.China

Chinese cherry （Prunus pseudocerasus L.） is an allotetraploid species and exhibits natural ***,the full-length cDNA sequences,functional analysis and the transcripts of S-RNase alleles in Chinese cherry cultivars are not *** the two cultivars Taixiaohongying and Laiyang Short Cherry with S1S2S3S4 genotypes,two S-RNases were transcribed in Northern blotting,and the two full-length cDNAs of S-RNase were cloned and *** the result,the transcribed S-RNases were S1-RNase and *** two complete cDNA sequences of S1-RNase and S2-RNase were registered as EU073938 and EU073939,respectively,and had characteristic structure of rosaceous S-RNases based on their sequences indicating that they had normal function for S-RNase in the *** S3-RNase and S4-RNase were not transcribed in the style and were nonfunctional for S-RNase,so S3m and S4m could be used to represent the nonfunctional S3-RNase and *** phylogenetic analysis implied that the S-RNases of Prunus,including Chinese cherry,had lower intra-specific similarity and diverged earlier than the divergence of species in Prunus.

关键词： Chinese cherry self-compatibility S-RNase Prunus tetraploid

Combination tanning mechanism inspired environmentally benign catalyst for efficient degradation of tetracycline

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Collagen and Leather 2023年第4期5卷 131-140页

作者： Meng xiao Shuangmei Liu Wenqian Qi Yu Peng Qingyu yan Hui mao College of Chemical Engineering Sichuan UniversityChengdu 610065People's Republic of China College of Chemistry and Materials Science Sichuan Normal UniversityChengdu 610066People's Republic of China School of Materials Science and Engineering Nanyang Technological UniversitySingapore 639798Singapore

The utilization of chelation reaction between metals and tannins is a common tanning method in leather ***,a novel combination tanning mechanism inspired environmentally benign catalyst(CMBT-Fe^(0))was synthesized by immobilizing Fe nanoparticles onto bayberry tannin(BT)grafted chitosan microfibers(CM).The obtained catalyst featured a well-defined microfibrous structure,on which Fe^(0)nanoparticles were highly dispersed to exhibit exceptional catalytic activity for the degradation of tetracycline(TC).The catalytic activity of CMBT-Fe^(0)was 1.72 times higher than that of the commercial Fe^(0)nanoparticles without immobilization,with 95.03%of TC degraded within 90.0 *** CMBT-Fe^(0)catalysts were recycled 6 times,with the removal rate of TC maintained at 82.56%.Furthermore,a possible mechanism responsible for the catalytic removal of TC was provided by analyzing the catalytic degradation products via liquid chromatography-mass ***,our investigation successfully developed efficient catalysts to address the concerned environmental issue of antibiotic pollution.

关键词： Vegetable tannin Combination tanning Environmental catalyst Tetracycline degradation