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Chinese Chemical Letters 2024年第9期35卷 331-339页

作者： Ruonan guo Heng Zhang Changsheng guo Ningqing Lv Beidou Xi jian Xu State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China School of Environment Tsinghua UniversityBeijing 100084China

The elimination of neonicotinoids(NEOs)from water has been a research priority due to their threats to human health and *** this study,we established the heterogeneous peroxymonosulfate(PMS)activation system using manganese catalyst(Mn NC)and cobalt catalyst(Co NC)to trigger the nonradical oxidation and synergistic oxidation pathway,respectively to remove *** results showed that the nonradical oxidation system exhibited superior NEOs degradation *** composition of organic pollutants in wastewater significantly impacted subsequent degradation *** charge distribution and reaction sites of various NEOs were analyzed using density functional theory(DFT)calculations,and it demonstrated the electron distribution and activity of NEOs were significantly influenced by the type and number of *** group(–NO_(2))and cyanide group(–C≡N)were identified as strong electron-withdrawing groups and prone to be attacked by negatively charged *** transformation of NEOs was analyzed,and result showed that the C and N sites adjacent to the nitro group and cyanide group were more susceptible to oxidation attacks.S and N atoms,which possess strong electronegativity and high electron cloud density,were identified as key active sites in the degradation *** outcomes of this study provide valuable guidance for the oriented regulation of oxidation pathways towards efficient removal of NEOs in water.

关键词： Fenton-like processes Molecular structure Neonicotinoids Nonradical oxidation Degradation pathway

Overvoltage Calculation Method for Sending System Under DC Fault Disturbance Considering the Influence of Renewable Energy

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 1865-1875页

作者： Haoyue Gong jianbo guo Qiang guo jian Zhang Qinyong Zhou Libo Zhang China Electric Power Research Institute Beijing 100192China

Bipolar blocking and commutation failure in the renewable energy transmission system through ultra-high voltage direct current will produce significant temporary *** paper analyzes the physical process of sending end grid overvoltage caused by two types of DC faults and establishes a DC overvoltage model considering renewable energy *** to characteristics of the sending end grid,the influence of the system equivalent impedance,the proportion of renewable energy output,the active and reactive power coefficients of the renewable energy sources during the low voltage ride through process on the overvoltage is analyzed respectively,and the relationship between the proportion of renewable energy output and the short-circuit ratio under the overvoltage constraint is *** validity and practicality of the model and analysis method proposed in this paper are verified by combining the typical transmission system at the sending end of the actual power grid and regional power grid systems.

关键词： Bipolar blocking commutation failure low voltage ride through renewable energy temporary overvoltage

Optimization of the co-closing law of guide vanes and blades for bulb turbines based on CFD

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Journal of Hydrodynamics 2024年第2期36卷 363-377页

作者： Hui Liu Yun-fa Lin Yong-guang Cheng Song Xue Mao-jia Tang jian Zhang jia-yi Fan State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China Dongfang Electric Machinery Co. Ltd.Deyang618000China

The load rejection transient process of bulb turbine units is critical to safety of hydropower stations,and determining appropriate closing laws of guide vanes(GVs)and runner blades(RBs)for this process is of *** this study,we proposed a procedure to optimize the co-closing law of GVs and RBs by using computational fluid dynamics(CFD),combined with the design of experiment(DOE)method,approximation model,and genetic optimization *** sensitivity of closing law parameters on the histories of head,speed,and thrust was analyzed,and a two-stage GVs’closing law associating with a linear RBs’closing law was *** results show that GVs dominate the transient characteristics by controlling the change of *** GVs’first-stage closing speed while shortening first-stage closing time can not only significantly reduce the maximum rotational speed but also suppress the water hammer pressure;slowing GVs’second-stage closing speed is conducive to controlling the maximum reverse axial *** directly affect the runner *** RBs’closing speed can further reduce the rotational speed and the maximum reverse axial *** safety margin of each control parameter,flow patterns,and pressure pulsations of a practical hydropower station were all improved after optimization,demonstrating the effectiveness of this method.

关键词： Bulb turbine load rejection transient process double regulation closing law optimization computational fluid dynamics(CFD)

Ultralow-phase-noise and broadband frequency-hopping coupled optoelectronic oscillator under quiet point operation

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Photonics Research 2024年第8期12卷 1785-1793页

作者： HUI LIU MINGYANG guo TIAN ZHANG jian DAI KUN XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Advancements in microwave photonics have yielded novel approaches for generating high-purity microwave *** these,optoelectronic oscillators(OEOs)and coupled optoelectronic oscillators(COEOs)have demonstrated the capability to generate frequency-independent microwaves with exceptionally low phase ***,the tunability of the oscillators is rather limited due to the necessity for narrowband electronic bandpass filters,presenting challenges in achieving both wide and rapid tuning ***,we present a COEO featuring ultralow phase noise,flexible tuning capability,and high *** is achieved through a quiet point(QP)-operated harmonic mode-locked fiber laser,which effectively mitigates optical amplifier noise and supermode competition,thus significantly diminishing the necessity for ultra-narrow electronic *** to the liberated tuning ability,we present an oscillator that can be tuned from 2 GHz to 18 GHz,with phase noise as low as-140 d Bc/Hz at 10 k Hz under the QP *** then illustrate the practical application of the proposed oscillator in generating frequency-hopping signals with consistent spurious modes less than-85 d Bc,absolute phase noise below-135 d Bc/Hz at 10 k Hz,hopping resolution of 1.25 MHz,and fractional frequency stability below 6.1×10^(-12)at 1 s averaging time when locked to a *** presented COEO structure emerges as a compelling solution for agile and low-noise microwave sources in advanced wireless communication and radar systems.

关键词： optoelectronic tuning amplifier

Inverse reliability analysis and design for tunnel face stability considering soil spatial variability

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1552-1564页

作者： Zheming Zhang jian Ji Xiangfeng guo Siang Huat Goh Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjing210098China Department of Civil and Environmental Engineering National University of SingaporeSingapore

The traditional deterministic analysis for tunnel face stability neglects the uncertainties of geotechnical parameters,while the simplified reliability analysis which models the potential uncertainties by means of random variables usually fails to account for soil spatial *** overcome these limitations,this study proposes an efficient framework for conducting reliability analysis and reliability-based design(RBD)of tunnel face stability in spatially variable soil *** three-dimensional(3D)rotational failure mechanism of the tunnel face is extended to account for the soil spatial variability,and a probabilistic framework is established by coupling the extended mechanism with the improved Hasofer-Lind-Rackwits-Fiessler recursive algorithm(iHLRF)as well as its inverse analysis *** proposed framework allows for rapid and precise reliability analysis and RBD of tunnel face *** demonstrate the feasibility and efficacy of the proposed framework,an illustrative case of tunnelling in frictional soils is presented,where the soil's cohesion and friction angle are modelled as two anisotropic cross-correlated lognormal random *** results show that the proposed method can accurately estimate the failure probability(or reliability index)regarding the tunnel face stability and can efficiently determine the required supporting pressure for a target reliability index with soil spatial variability being taken into ***,this study reveals the impact of various factors on the support pressure,including coefficient of variation,cross-correlation between cohesion and friction angle,as well as autocorrelation distance of spatially variable soil *** results also demonstrate the feasibility of using the forward and/or inverse first-order reliability method(FORM)in high-dimensional stochastic *** is hoped that this study may provide a practical and reliable framework for determining the stability of tunnels in complex

关键词： Limit analysis Tunnel face stability Spatial variability HLRF algorithm Inverse reliability method

Ramsey Numbers of Trees Versus Multiple Copies of Books

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 600-612页

作者： Xiao-bing guo Si-nan HU Yue-jian PENG School of Mathematical Sciences Luoyang Normal UniversityLuoyang 471934China School of Mathematics Hunan UniversityChangsha 410082China

Given two graphs G and H,the Ramsey number R(G,H) is the minimum integer N such that any two-coloring of the edges of K_(N) in red or blue yields a red G or a blue *** v(G) be the number of vertices of G and χ(G) be the chromatic number of *** s(G) denote the chromatic surplus of G,the number of vertices in a minimum color class among all proper χ(G)-colorings of *** showed that R(G,H)≥(v(G)-1)(χ(H)-1)+s(H) if G is connected and v(G)≥s(H).A connected graph G is H-good if R(G,H)=(v(G)-1)(χ(H)-1)+s(H).Let tH denote the disjoint union of t copies of graph H,and let G∨H denote the join of G and *** a complete graph on n vertices by K_(n),and a tree on n vertices by T_(n).Denote a book with n pages by B_(n),i.e.,the join K_(2) ∨■.Erd?s,Faudree,Rousseau and Schelp proved that T_(n) is B_(m)-good if n≥*** this paper,we obtain the exact Ramsey number of T_(n) versus 2B_(2).Our result implies that T_(n) is 2B_(2)-good if n≥5.

关键词： ramsey number ramsey goodness tree book

Characterization and Monitoring of Transient Enamine Radical Intermediates in Photoredox/Chiral Primary Amine Synergistic Catalytic Cycle

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CCS Chemistry 2024年第10期6卷 2420-2426页

作者： Shixue Zhang Liang Cheng jian-Qing Qi Zongbin jia Long Zhang Lei jiao Xingwei guo Sanzhong Luo Center of Basic Molecular Science(CBMS) Department of ChemistryTsinghua UniversityBeijing 100084

Enamine-derived radicals are crucial intermediates in singly occupied molecular orbital(SOMO)***,observing them directly is elusive and remains a long-standing ***,an advanced time-resolved electron paramagnetic resonance technique was employed to characterize and monitor the key intermediates in photoredox transformations by primary aminocatalysis on a microsecond *** transient enamine radical cation,generated by single electron transfer(SET),and the deprotonated form ofα-imino radical intermediates were directly observed for the first time,both spectroscopically and *** reactions with styrene,enamine radical cation was found to be faster thanα-imino radical by one order of *** revealed the subtle role of deprotonation associated with secondary enamine radical cation in the photoredox transformations by primary aminocatalysis.

关键词： aminocatalysis radical chemistry electron paramagnetic resonance direct observation time-resolved technique

Viscoacoustic generalized screen propagator in constant-Q model

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Petroleum Science 2024年第4期21卷 2356-2369页

作者： Zhong-Kui Dai jia-Chun You Xing-guo Huang Wei Liu College of Geophysics Chengdu University of Technology College of Instrumentation and Electrical Engineering Jilin University

When seismic waves propagate through the geological formation, there is a significant loss of energy and a decrease in imaging resolution, because of the viscoacoustic properties of subsurface medium. This profoundly impacts seismic wavefield propagation, imaging and interpretation. To accurately image the true structure of subsurface medium, the consensus among geophysicists is to no longer treat subsurface medium as ideal homogeneous medium, but rather to incorporate the viscoacoustic properties of subsurface medium. Based on the generalized screen propagator using conventional acoustic wave equation(acoustic GSP), our developed method introduces viscoacoustic compensation strategy, and derives a one-way wave generalized screen propagator based on time-fractional viscoacoustic wave equation(viscoacoustic GSP). In numerical experiments, we conducted tests on two-dimensional multi-layer model and the Marmousi model. When comparing with the acoustic GSP using the acoustic data, we found that the imaging results of the viscoacoustic GSP using the viscoacoustic data showed a significant attenuation compensation effect, and achieved imaging results for both algorithms were essentially consistent. However, the imaging results of acoustic GSP using viscoacoustic data showed significant attenuation effects, especially for deep subsurface imaging. This indicates that we have proposed an effective method to compensate the attenuated seismic wavefield. Our application on a set of real seismic data demonstrated that the imaging performance of our proposed method in local areas surpassed that of the conventional acoustic GSP. This suggests that our proposed method holds practical value and can more accurately image real subsurface structures while enhancing imaging resolution compared with the conventional acoustic GSP. Finally, with respect to computational efficiency, we gathered statistics on running time to compare our proposed method with conventional Q-RTM, and it is evid

关键词： One-way wave equation Viscoacoustic wave equation Generalized screen propagator Attenuation and dispersion effects

Regulation of Ti(C,N)deposition on hot surface of refractory in blast furnace hearth

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Journal of Iron and Steel Research International 2024年第6期31卷 1423-1435页

作者： jian Cao Cui Wang Jjan-liang Zhang Ke-xin jiao guo-hua Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

Ti(C,N)concentration was found to be lower on the hearth sidewall of a blast furnace and increased gradually toward the bottom of the blast *** Ti(C,N)protective layer in a blast furnace is ***,the formation of a Ti(C,N)protective layer was promoted by studying the heterogeneous nucleation principle of titanium compounds on different substances and regulation measures for the deposition process of titanium compounds on refractories or *** lattice disregistry between the titanium compounds and the main components in the refractory or the main impurities in the protective layer was calculated using a two-dimensional disregistry equation to study the heterogeneous nucleation principle of titanium *** results revealed that in refractory materials,the heterogeneous nucleation of carbonitride is weak when C,SiO_(2),and Al_(2)O_(3) are used as heterogeneous nucleation substrates,and the heterogeneous nucleation of carbonitride is strong when TiO_(2) and SiC are used as heterogeneous nucleation *** nucleation phases,TiC,TiN,Ti(C_(0.3),N_(0.7)),and Ti(C_(0.5),N_(0.5))have similar heterogeneous nucleation ability in single component refractory,and the type of carbonitride has little effect on the lattice *** impurities in the protective layer as the substrate phases are not conducive to the heterogeneous nucleation of *** CaS was used as the substrate phase,the heterogeneous nucleation ability of carbonitride was the *** carbon and alumina were not conducive to the heterogeneous nucleation of carbonitride,but carbon was more unfavourable than alumina.

关键词： Ti(C,N) Lattice disregistry Lattice constant Heterogeneous nucleation Regulation measure

Short-term Safety and Efficiency of Cryoablation for Rena Sympathetic Denervation in a Swine Model

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Chinese Medical Journal 2015年第6期128卷 790-794页

作者： Meng Ji Li Shen Yi-ZheWu Zhi-Feng Yao jia-Sheng Yin jia-Hui Chen jian-guo jia Ling-Juan Qiao Peng LiD Jun-Bo Ge Institutes of Biomedical Science Fudan University Shanghai 200032 China Department of Cardiology Zhongshan Hospital Fudan University Shanghai 200032 China Cyrofocus Medtech Corporation Shanghai 200120 China

Background:Renal sympathetic nerves are involved in the reflective activation of the sympathetic nervous system in circulatory ***-based renal denervation (RDN) ameliorated treatment-resistant hypertension safely,but 10％-20％ of treated patients are nonresponders to radiofrequency *** purpose of this study was to investigate the safety and efficiency of cryoablation for sympathetic denervation in a swine model and to explore a new way of ***:Seven swines randomly assigned to two groups:Renal cryoablation (CR) group and control *** control group underwent renal angiogram *** CR group underwent renal angiogram plus bilateral renal *** angiograms via femoral were performed before denervation,after denervation and prior to the sacrifice to access the diameter of renal arterial and the pressure of aorta *** of the swine was performed on 28-day to access norepinephrine (NE) changes of the renal cortex and the changes of renal ***:Cryoablation did not induce severe complications at any time *** was no significant change in diameter of renal *** reduced systolic blood pressure (BP) from 145.50 ± 9.95 mmHg at baseline to 119.00 ± 14.09 *** was a slight but insignificant decrease in diastolic *** main nerve changes at 28-day consisted of necrosis with perineurial fibrosis at the site of CR exposure in conjunction with the nerve *** with the control group,renal tissue NE of CR group decreased by 89.85％.Conclusions:Percutaneous catheter-based cryoablation of the renal artery is *** could effectively reduce NE storing in the renal cortex,and the efficiency could be maintained 28-day at least.

关键词： Cryoablation Renal Sympathetic Denervation Sympathetic Nerve System