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A FOURTH ORDER DERIVATIVE-FREE OPERATOR MARCHING METHOD FOR HELMHOLTZ EQUATION IN WAVEGUIDES

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Journal of Computational Mathematics 2007年第6期25卷 719-729页

作者： ya yan lu Department of Mathematics City University of Hong Kong Kowloon Hong Kong

A fourth-order operator marching method for the Helmholtz equation in a waveguide is developed in this paper. It is derived from a new fourth-order exponential integrator for linear evolution equations. The method improves the second-order accuracy associated with the widely used step-wise coupled mode method where the waveguide is approximated by segments that are uniform in the propagation direction. The Helmholtz equation is solved using a one-way reformulation based on the Dirichlet-to-Neumann map. An alternative version closely related to the coupled mode method is also given. Numerical results clearly indicate that the method is more accurate than the coupled mode method while the required computing effort is nearly the same.

关键词： Helmholtz equation Waveguides Dirichlet-to-Neumann map Operator marching.

Some Techniques for Computing Wave Propagation in Optical Waveguides

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Communications in Computational Physics 2006年第6期1卷 1056-1075页

作者： ya yan lu Department of Mathematics City University of Hong KongKowloonHong Kong

Optical wave-guiding structures that are non-uniform in the propagation direction are fundamental building blocks of integrated optical *** simulation of lightwaves propagating in these structures is an essential tool to engineers designing photonic *** this paper,we review recent developments in the most widely used simulation methods for frequency domain propagation problems.

关键词： Optical waveguides operator marching method mode matching method beam propagation method bidirectional propagation methods rational approximations

Dirichlet-to-Neumann Map Method with Boundary Cells for Photonic Crystals Devices

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Communications in Computational Physics 2011年第1期9卷 113-128页

作者： Jianhua Yuan ya yan lu Department of Mathematics Beijing University of Posts and TelecommunicationsBeijing 100876China Department of Mathematics City University of Hong KongKowloonHong Kong

In a two-dimensional(2D)photonic crystal(PhC)composed of circular cylinders(dielectric rods or air holes)on a square or triangular lattice,various PhC devices can be created by removing or modifying some *** existing numerical methods for PhC devices give rise to large sparse or smaller but dense linear systems,all of which are expensive to solve if the device is *** a previous work[*** et al.,Optics Express,16(2008),17383-17399],an efficient Dirichlet-to-Neumann(DtN)map method was developed for general 2D PhC devices with an infinite background PhC to take full advantage of the underlying lattice *** DtN map of a unit cell is an operator that maps the wave field to its normal derivative on the cell boundary and it allows one to avoid computing the wave field in the interior of the unit *** this paper,we extend the DtN map method to PhC devices with a finite background *** there is no bandgap effect to confine the light in a finite PhC,a different technique for truncating the domain is *** enclose the finite structure with a layer of empty boundary and corner unit cells,and approximate the DtN maps of these cells based on expanding the scattered wave in outgoing plane *** method gives rise to a relatively small and sparse linear systems that are particularly easy to solve.

关键词： Photonic crystal Dirichlet-to-Neumann map numerical simulation

Thermoregulated Organic Biphasic Hydrogenation of 1-Octene Catalyzed by Ru/PETPP Complex

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Chinese Chemical Letters 2006年第2期17卷 255-257页

作者： ya Dong lu yan Hua WANG Zi Lin JIN State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116012

Thermoregulated organic biphasic system composed of triethylene glycol monomethyl ether （TGME） and n-heptane was first applied to the hydrogenation of 1-octene. Under the optimal conditions： P（H2）=5.0MPa, T=80℃, t=3h, 1-octene/Ru=1000 （molar ratio）, the yield of n-octane reached up to 99.6%. Furthermore, the simply decanted catalyst could be reused for 10 times without apparent loss of catalytic activity.

关键词： Thermoregulated organic biphasic system hydrogenation 1-octene ruthenium.

Rh nanoparticles stabilized by PEG-substituted triphenyl-phosphine:A highly active and recyclable catalyst for aqueous biphasic hydrogenation of benzene

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Chinese Chemical Letters 2010年第9期21卷 1067-1070页

作者： ya Dong lu yan Hua Wang Zi Lin Jin State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116012 China

Rh nanoparticles stabilized by PEG-substituted triphenyl-phosphine（PETPP,P[C6H4-p-（OCH2CH2）nOH]3） combining double stabilization effects demonstrated high activity and good recyclability in aqueous biphasic hydrogenation of *** value of turnover frequency（TOF） was 3333 h^-***,the rhodium nanoparticle catalyst could be easily recycled for five times without loss in activity.

关键词： Hydrogenation Nanoparticles Rhodium PETPP Aqueous biphasic catalysis

Ultrastructure and electrophysiology of astrocytes differentiated from adult adipose-derived stromal cells

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Chinese Medical Journal 2011年第17期124卷 2656-2660页

作者： OU ya YUAN Xiao-dong CAI ya-nan lu yan-hui Department of Neurology Kailuan General Hospital Hebei United University Tangshan Hebei 063000 China

Background Adipose-derived stromal cell （ADSC） differentiation into neural cells in vitro is becoming widely studied. However, there are few reports on astrocytes following differentiation, and particularly on maturation and electrophysiology. In this study, we used various methods to determine ADSC-derived astrocyte maturity. Methods Chemical induction with isobutylmethylxanthine （IBMX） was used to differentiate adult ADSCs into astrocytes followed by hematoxylin-eosin （HE） staining to observe morphology and transmission electron microscopy for cellular ultrastructure assessment. Immunofluorescence was used to detect expression of neural stem cell marker nestin as well as glial markers glial fibrillary acidic protein （GFAP） and S-100. In addition, we measured membrane potentials in bis-（1,3-dibarbituric acid） trimethine oxanol-labeled ADSCs and astrocytes by stimulation with a high potassium solution under an inverted fluorescence microscope. Finally, cell cycle distribution was detected by flow cytometry. Results Typical astrocyte morphology was shown by HE staining after 48-hour differentiation. Glial fibril was observed with transmission electron microscopy. GFAP and S-100 were not expressed in the control group, but were expressed within 24-hour differentiation and reached a maximum at day 14 with no change up to day 28. Nestin was weakly expressed in control cells and also reached a maximum at day 14 with the percentage of positive cells constant until day 21 followed by a decrease. Differentiated cell membrane potentials after stimulation with potassium were slightly increased, and then gradually declined over time. There was no significant membrane potential change in the control group. Flow cytometry showed that the percentage of cells in G0/G1 phase was 93% and only 5% in S phase. Conclusion ADSCs were differentiated into mature astrocytes with typical characteristics including morphology, ultrastructure, marker protein expression, mature potassium channel

关键词： adult adipose-derived stromal cells differentiate astrocytes ultrastructure membrane potential

GFRF R-CNN:Object Detection Algorithm for Transmission Lines

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Computers, Materials & Continua 2025年第1期82卷 1439-1458页

作者： Xunguang yan Wenrui Wang Fanglin lu Hongyong Fan Bo Wu Jianfeng Yu Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai201210China University of Chinese Academy of Sciences Beijing100049China Jingwei Textile Machinery Co. Ltd.Beijing100176China

To maintain the reliability of power systems,routine inspections using drones equipped with advanced object detection algorithms are essential for preempting power-related *** increasing resolution of drone-captured images has posed a challenge for traditional target detection methods,especially in identifying small objects in high-resolution *** study presents an enhanced object detection algorithm based on the Faster Regionbased Convolutional Neural Network(Faster R-CNN)framework,specifically tailored for detecting small-scale electrical components like insulators,shock hammers,and screws in transmission *** algorithm features an improved backbone network for Faster R-CNN,which significantly boosts the feature extraction network’s ability to detect fine *** Region Proposal Network is optimized using a method of guided feature refinement(GFR),which achieves a balance between accuracy and *** incorporation of Generalized Intersection over Union(GIOU)and Region of Interest(ROI)Align further refines themodel’s *** results demonstrate a notable improvement in mean Average Precision,reaching 89.3%,an 11.1%increase compared to the standard Faster *** highlights the effectiveness of the proposed algorithm in identifying electrical components in high-resolution aerial images.

关键词： Faster R-CNN transmission line object detection GIOU GFR

High Fe‑Loading Single‑Atom Catalyst Boosts ROS Production by Density Effect for Efficient Antibacterial Therapy

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Nano-Micro Letters 2025年第2期17卷 187-203页

作者： Si Chen Fang Huang Lijie Mao Zhimin Zhang Han Lin Qixin yan Xiangyu lu Jianlin Shi Department of Cardiology Shanghai Tenth People’s HospitalSchool of MedicineTongji UniversityShanghai 200092People’s Republic of China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050People’s Republic of China Shanghai Frontiers Science Center of Nanocatalytic Medicine School of MedicineTongji UniversityShanghai 200092People’s Republic of China

The current single-atom catalysts(SACs)for medicine still suffer from the limited active site ***,we develop a synthetic method capable of increasing both the metal loading and mass-specific activity of SACs by exchanging zinc with *** constructed iron SACs(h^(3)-FNC)with a high metal loading of 6.27 wt%and an optimized adjacent Fe distance of~4 A exhibit excellent oxidase-like catalytic performance without significant activity decay after being stored for six months and promising antibacterial ***,a“density effect”has been found at a high-enough metal doping amount,at which individual active sites become close enough to interact with each other and alter the electronic structure,resulting in significantly boosted intrinsic activity of single-atomic iron sites in h^(3)-FNCs by 2.3 times compared to low-and medium-loading ***,the overall catalytic activity of h^(3)-FNC is highly improved,with mass activity and metal mass-specific activity that are,respectively,66 and 315 times higher than those of commercial Pt/*** addition,h^(3)-FNCs demonstrate efficiently enhanced capability in catalyzing oxygen reduction into superoxide anion(O_(2)·^(−))and glutathione(GSH)*** in vitro and in vivo assays demonstrate the superior antibacterial efficacy of h^(3)-FNCs in promoting wound *** work presents an intriguing activity-enhancement effect in catalysts and exhibits impressive therapeutic efficacy in combating bacterial infections.

关键词： Nanocatalytic medicine Single-atom catalysts Reactive oxygen species(ROS) High metal loading Oxidase catalysis

Spatiotemporal characteristics and influencing factors of vegetation water use efficiency on the Tibetan Plateau in 2001–2020

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Journal of Geographical Sciences 2025年第1期35卷 39-64页

作者： HE Chenyang WANG yanjiao yan Feng lu Qi School of Ecological and Environmental Science East China Normal University Institute of Ecological Conservation and Restoration Chinese Academy of Forestry National Climate Center China Meteorological Administration

Water use efficiency （WUE）,as a pivotal indicator of the coupling degree within the carbon–water cycle of ecosystems,holds considerable importance in assessment of the carbon–water balance within terrestrial ***,in the context of global warming,WUE evolution and its primary drivers on the Tibetan Plateau remain *** study employed the ensemble empirical mode decomposition method and the random forest algorithm to decipher the nonlinear trends and drivers of WUE on the Tibetan Plateau in 2001–*** indicated an annual mean WUE of 0.8088 gC/mm·m2across the plateau,with a spatial gradient reflecting decrease from the southeast toward the *** manifesting monotonous trends of increase or decrease in WUE accounted for 23.64%and 9.69%of the total,***,66.67%of the region exhibited trend reversals,i.e.,39.94%of the area of the Tibetan Plateau showed transition from a trend of increase to a trend of decrease,and 26.73%of the area demonstrated a shift from a trend of decrease to a trend of *** factors accounted for 70.79%of the variability in *** leaf area index and temperature served as the major driving forces of WUE variation.

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