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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第1期10卷 54-61页

作者： chang-shui feng Wei-qiu ZHU Institute of Mechatronic Engineering Hangzhou Dianzi University Hangzhou 310018 China State Key Laboratory of Fluid Power Transmission and Control Department of Mechanics Zhejiang University Hangzhou 310027 China

We studied the response of harmonically and stochastically excited strongly nonlinear oscillators with delayed feedback bang-bang control using the stochastic averaging method. First, the time-delayed feedback bang-bang control force is expressed approximately in terms of the system state variables without time delay. Then the averaged It6 stochastic differential equations for the system are derived using the stochastic averaging method. Finally, the response of the system is obtained by solving the Fokker-Plank-Kolmogorov （FPK） equation associated with the averaged lt6 equations. A Duffing oscillator with time-delayed feedback bang-bang control under combined harmonic and white noise excitations is taken as an example to illus- trate the proposed method. The analytical results are confirmed by digital simulation. We found that the time delay in feedback bang-bang control will deteriorate the control effectiveness and cause bifurcation of stochastic jump of Duffing oscillator.

关键词： Nonlinear system Delayed feedback bang-bang control Combined harmonic and white noise excitation Stochastic averaging Stationary response Stochastic jump

Quantifying spatial scale of positive and negative terrains pattern at watershed-scale:Case in soil and water conservation region on Loess Plateau

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Journal of Mountain Science 2017年第8期14卷 1642-1654页

作者： YANG feng zhou Yi School of Geography and Tourism Shaanxi Normal University

The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis(TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches(e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction(i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern alsoclearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors(i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China' Loess Plateau, it is crucial to u

关键词： Positive and negative terrains TTLQV Spatial pattern scale Loess landforms Loess Plateau

T cell metabolism in obesity and beyond:comments on‘DsbA-L deficiency in T cells promotes diet-induced thermogenesis through suppressing IFN-y production’

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Journal of Molecular Cell Biology 2021年第5期13卷 389-391页

作者： Haiyan zhou feng Liu National Clinical Research Center for Metabolic Diseases Metabolic Syndrome Research Centerand Department of Metabolism and EndocrinologyThe Second Xiangya Hospital of Central South UniversityChangsha 410011China Department of Pharmacology University of Texas Health Science Center at San AntonioSan AntonioTX 78229USA

T cells have long been known as the core of adaptive immunity and play piv-otal roles in host defense(Zhu et al.,2010).There are two main types of T cells in our body,cytotoxic T cells(CD8^(+))and helper T(Th)cells(CD4^(+)),the latter comprised of Th1,Th2,Th17,and Treg *** evidence supports that metabolic reprogramming of T cells leads to dramatic changes in tissue microenvironments,which may alter whole-body energy homeostasis and metabolism,beyond their roles in adaptive immunity(Varanasi et al.,2020).

关键词： metabolism immunity

An improved CESE method and its application to steady-state coronal structure simulation

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Science China Earth Sciences 2014年第1期57卷 153-166页

作者： zhou YuFen feng XueShang SIGMA Weather Group State Key Laboratory for Space Weather Center for Space Science and Applied ResearchChinese Academy of Sciences

This paper presents an improved space-time conservation element and solution element(CESE)method by applying a non-staggered space-time mesh system and simply improving the calculation of flow variables and applies it to magnetohydrodynamics(MHD)*** improved CESE method can improve the solution quality even with a large disparity in the Courant number(CFL)when using a fixed global marching ***,for a small CFL(say<0.1),the method can significantly reduce the numerical dissipation and retain the solution quality,which are verified by two benchmark *** meanwhile,comparison with the original CESE scheme shows better resolution of the improved scheme ***,we demonstrate its validation through the application of this method in three-dimensional coronal dynamical structure with dipole magnetic fields and measured solar surface magnetic fields as the initial input.

关键词： improved CESE scheme numerical dissipation steady-state coronal structure

Significant photocatalytic enhancement in methylene blue degradation of Bi2WO6 photocatalysts via graphene hybridization

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Journal of Advanced Ceramics 2012年第1期1卷 72-78页

作者： feng zhou Yongfa ZHU Department of Materials Science and Engineering Dalian Maritime UniversityDalian 116026China Department of Chemistry Tsinghua UniversityBeijing 100084China

The hybridization of graphene with Bi_(2)WO_(6)photocatalysts was employed to enhance the photocatalytic *** photocatalytic activity enhancements were dependent on the amount of graphene and it was found that the optimal hybridized amount of graphene was about 1.5 wt%,which was close to the monolayer dispersing of graphene on Bi_(2)WO_(6)*** to four times of the photocatalytic activity was enhanced by the hybridization of graphene,compared with that of pristine Bi_(2)WO_(6).The enhancement mechanism of the photocatalytic activity was attributed to the higher separation efficiency and the inhibition of recombination of photoinduced electron-hole *** electronic interaction was verified by the photoelectrochemical measurements.

关键词： powders-chemical preparation carbon nanocomposites photocatalyst

Porous carbon nanofibers derived from low-softening-point coal pitch towards all-carbon potassium ion hybrid capacitors

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Rare Metals 2022年第11期41卷 3706-3716页

作者： Guang-Yuan Wang Xiao-Hong Wang Jin-feng Sun Ya-Min Zhang Lin-Rui Hou chang-zhou Yuan School of Materials Science and Engineering University of JinanJinan250022China

Potassium ion hybrid capacitors(PIHC)have promising applications in medium and large-scale energy storage systems due to their high energy/power density,abundant potassium resource and low ***,the slow kinetics of battery-type anodes originating from the large-size K+results in a mismatch between the two electrodes,rendering the modest energy density of ***,we first develop an electrospinning strategy to successfully synthesize fibrous precursor by using the HNO_(3)pre-oxidized low-softening-point coal pitch as the low-cost raw *** further carbonization or KOH activation,the two types of carbon nanofibers(CNF)are fabricated as anode and cathode materials,respectively,towards the dual-carbon PIHC *** to its threedimensional interconnected porous conducting network and large layer spacing,the resulted CNF anode material is endowed with high reversible capacities,excellent rate and long cycle ***,the activated CNF cathode with a large surface area of 2169 m^(2)·g^(-1)exhibits excellent capacitive performance.A PIHC constructed with the two fibrous electrodes delivers an energy density of110.0 Wh·kg^(-1)at 200.0 W kg^(-1),along with a capacitance retention of 83.5%after 10,000 cycles at 1.0 A·g^(-1).The contribution here provides a cost-efficiency avenue and platform for advanced dual-carbon PIHC.

关键词： Potassium ion hybrid capacitors(PIHC) Low-softening-point coal pitch Carbon nanofibers(CNF) Dual-carbon devices Long durability

INVESTIGATION OF VISCOUS FLOW FIELD AROUND AN APPENDED REVOLUTION BODY WITH GUIDE VANE PROPELLER

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Journal of Hydrodynamics 2000年第1期12卷 79-86页

作者： zhou, Liandi Zhao, feng National Lab of Hydrodynamics Wuxi China

A RANS (Reynolds-averaged Navier-stokes) solver is presented to numerically simulate the viscous wake of an appended revolution body with guide vane propeller at the Reynolds number 107. The k-Ε turbulence model together with wall function is used. The resulting finite difference equations are solved by SIMPLEC and ADI. The technique of rising up the bottom surface is presented to overcome radial contraction problems in the Cartesian coordinate system. The three-dimensional body model is successfully use to represent the guide vane and propeller actions. The detailed flow characteristics, especially the counter-swirl component generated by the guide vane in the propeller inflow, are numerically seized successfully. The qualitative and quantitative consistence between experiment and calculation is shown. The computational axial velocity of the propeller disk plane comes up to engineering requirement.

关键词： Computer simulation Fluid dynamics Propellers Reynolds number Wakes

Effects of seven different companion plants on cucumber productivity, soil chemical characteristics and Pseudomonas community

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Journal of Integrative Agriculture 2017年第10期16卷 2206-2214页

作者： chang Chun-ling FU Xue-peng zhou Xin-gang GUO Mei-yu WU feng-zhi Department of Horticulture Northeast Agricultural University Harbin 150030 P.R.China

Companion cropping can influence cucumber productivity by altering soil chemical characteristics and microbial communities. However, how these alterations affect the growth of cucumber is still unknown. In this study, seven different plant species were selected as companion plants for testing their effects on cucumber productivity. The effects of different companion plants on changes in soil chemical properties such as electrical conductivity （EC） and contents of essential nutrients as well as the structure and abundance of the soil Pseudomonas community were evaluated. The results showed a higher cucumber yield in the wheat/cucumber companion system than that in the cucumber monocultured and other companion cropping systems. The lowest phosphorus （P） and potassium （K） contents in the soil were found in the cucumber monocultured system, and the highest NO3＋-N and NH4＊-N contents were observed in the rye/cucumber companion system. PCR-denaturing gradient gel electrophoresis （DGGE） and real-time PCR analysis showed that the trifolium/cucumber companion system increased the diversity of the soil Pseudomonas community, while the chrysanthemum/cucumber companion system increased its abundance. Interestingly, plant-soil feedback trials revealed that inoculating the soil of the wheat/cucumber companion system increased the growth of cucumber seedlings. In conclusion, the effects of different companion plants on cucumber productivity, soil chemical characteristics and the soil Pseudomonas community were different, and wheat was a more suitable companion plant for increasing cucumber productivity. In addition, the altered microbial community caused by companion cropping with wheat contributed to increased cucumber productivity.

关键词： cucumber companion plants soil chemical characteristics Pseudomonas community

Electrocatalytic oxygen reduction performances of surface Ag granular packs electrodeposited from dual-phase Ag_(35.5)Zn_(64.5) precursor alloys by triangle wave potential cycling

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Rare Metals 2021年第12期40卷 3531-3542页

作者： Jia-Yu Luo Piao-Piao Han Zhen-Hua Dan Tao Tang feng-Xiang Qin Hui chang Lian zhou College of Materials Science and Engineering and Tech Institute for Advanced Materials Nanjing Tech UniversityNanjing 210009China State Key Laboratory of Advanced Metals and Materials University of Science and Technology BeijingBeijing 110083China School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China

Surface Ag granular packs(SAgPs) have been fabricated from dual-phase Ag_(35.5)Zn_(64.5) precursor alloy consisting of both e and c phases by using a facile one-step triangle wave potential cycling in 0.5 mol·L^(-1) *** the continuous potential cyclic sweeping, the c phases preferentially dissolve during the anodic scan and dominant reduction reactions of Ag cations lead to redeposition and accumulation of Ag atoms together to form SAg Ps during cathodic scan. The e phases stay inactive to form a continuous skeleton in the inner regions. SAg Ps with an average particle size of 94-129 nm can be obtained at scan rates of 25, 50 and 100 mV·s^(-1) for 100 triangle wave potential cycles. SAgPs formed at a scan rate of 50 mV·s^(-1) exhibit superior oxygen reduction reaction performances with the onset potential of 0.93 V, half-wave potential of 0.72 V and an electron transfer number of *** above-mentioned SAgPs have superior stabilities as ORR catalysts.

关键词： Surface Ag granular packs Dual-phase Ag_(35.5)Zn_(64.5)precursor alloy Triangle wave potential cycling Oxygen reduction reaction catalysts Selective dissolution Intermetallic phases

Development of a sensitive and reliable droplet digital PCR assay for the detection of ‘Candidatus Liberibacter asiaticus'

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Journal of Integrative Agriculture 2018年第2期17卷 483-487页

作者： ZHONG Xi LIU Xue-lu LOU Bing-hai zhou chang-yong WANG Xue-feng National Citrus Engineering Research Center Citrus Research Institute Chinese Academy of Agricultural Sciences/Southwest University Guangxi Key Laboratory of Citrus Biology Guangxi Academy of Specialty Crops

Citrus Huanglongbing（HLB, yellow shoot disease） is one of the most serious citrus diseases worldwide. To better improve the detection sensitivity, a droplet digital PCR（ddPCR） assay was developed for the rapid detection of ‘Candidatus Liberibacter asiaticus＇（Las）, the putative causal agent of HLB. The detection of sensitivity comparison using positive plasmid indicated that dd PCR was superior to quantitative PCR（qPCR） for detecting and quantifying Las at low concentrations. The Las detection of 40 field samples also showed that six of 13 asymptomatic samples（46.15%） with high Ct value（〉35） were positive by dd PCR. This methodology showed great potential for early HLB infection diagnosis.

关键词： citrus Huanglongbing early diagnosis droplet digital PCR