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Numerical Investigation on Characteristics of Supercritical CO_(2)Heat Transfer in Vertical Circular Tubes with Circumferentially Half-Side Heating

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Journal of Thermal Science 2024年第5期33卷 1744-1756页

作者： ZHANG Yan ZHANG Xinyi YAN Chenshuai wu wenhua GAO Erman School of Energy and Power Engineering Northeast Electric Power UniversityJilin 132012China

The design of heat exchangers in the advanced supercritical power conversion system cannot be separated from the study of heat transfer ***-side heating mode is often encountered for solar receiver and supercritical ***,the characteristics of supercritical CO_(2)(sCO_(2))convection heat transfer in vertical tubes with circumferentially half-side heating was numerically investigated through the SST k-ωturbulent model which matches well with the experimental ***,heat transfer between sCO_(2)upflow and downflow was *** to film boiling heat transfer at subcritical pressure,numerical results were processed according to the supercritical pseudo-phase transition hypothesis,with liquid-like phase in the tube core region and vapor-like film in the region near the heated tube *** structure of two layers was demarcated by pseudo-critical temperature T_(pc).Therefore,sCO_(2)heat transfer was assessed according to double thermal resistances caused by vapor-like film near the wall and core liquid-like *** findings suggest that wall temperature for upflow is higher than that for downflow,which is attributed to larger thermal resistance in the fluid domain for upflow than that for *** difference guarantees the excellent heat transfer performance for downflow than *** is also further concluded that the formation of vapor-like film near the wall due to pseudo-phase transition plays a key role in dominating wall temperature and inducing heat transfer deterioration in half-side heating *** present contribution is significant to the design of supercritical heat exchanger under half-side heating mode.

关键词： supercritical CO_(2) pseudo-phase transition half-side heating thermal resistance flow direction

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Current Model Analysis of South China Sea Based on Empirical Orthogonal Function(EOF) Decomposition and Prototype Monitoring Data

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Journal of Ocean University of China 2019年第2期18卷 305-316页

作者： wu wenhua LIU Ming YU Siyuan WANG Yanlin Department of Engineering Mechanics Faculty of Vehicle and Mechanics Dalian University of Technology State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology School of Ocean Science and Technology Dalian University of Technology

Environmental load is the primary factor in the design of offshore engineering structures and ocean current is the principal environmental load that causes underwater structural failure. In computational analysis, the calculation of current load is mainly based on the current profile. The current profile model, which is based on a structural failure criterion, is conducive to decreasing the uncertainty of the current load. In this study, we used prototype monitoring data and the empirical orthogonal function(EOF) method to investigate the current profile in the South China Sea and its correlation with the design of underwater structural strength and the dynamic design of fatigue. The underwater structural strength design takes into account the size of the structure and the service water depth. We propose profiles for the overall and local designs using the inverse first-order reliability method(IFORM). We extracted the characteristic profile current(CPC) of the monitored sea area to solve dynamic design problems such as vortex-induced vibration(VIV). We used random sampling to verify the feasibility of using the EOF method to calculate the CPC from the current data and identified the main problems associated with using the CPC, which deserve close attention in VIV design. Our research conclusions provide direct references for determining current load in this sea area. This analysis method can also be used in the analysis of other sea areas or field variables.

关键词： current profile model failure criteria prototype monitoring inverse first-order reliability method(IFORM) Characteristic profile current(CPC)

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A multi-target tracking algorithm based on Gaussian mixture model

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Journal of Systems Engineering and Electronics 2020年第3期31卷 482-487页

作者： SUN Lili CAO Yunhe wu wenhua LIU Yutao National Laboratory of Radar Signal Processing Xidian UniversityXi’an 710071China Science and Technology on Communication Networks Laboratory Shijiazhuang 050081China

Since the joint probabilistic data association(JPDA)algorithm results in calculation explosion with the increasing number of targets,a multi-target tracking algorithm based on Gaussian mixture model(GMM)clustering is *** algorithm is used to cluster the measurements,and the association matrix between measurements and tracks is constructed by the posterior *** with the traditional data association algorithm,this algorithm has better tracking performance and less computational *** results demonstrate the effectiveness of the proposed algorithm.

关键词： multiple-target tracking Gaussian mixture model(GMM) data association expectation maximization(EM)algorithm

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HCl guided morphology and conductivity of chiral PPy nanostructures toward efficient electromagnetic wave absorption

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Science China(Technological Sciences) 2022年第4期65卷 837-848页

作者： YANG XiaoFen FAN BaoXin WANG XinXin wu LiShan YAO QiBin TONG GuoXiu wu wenhua CHEN DaBo College of Chemistry and Life Sciences Key Laboratory of the Ministry of Education for Advanced Catalysis MaterialsZhejiang Normal UniversityJinhua 321004China NEW MORE Graphene Application Technology Co. Ltd.Jinhua 321004China

To solve the severe electromagnetic(EM)radiation from the widespread application of electronic equipment,we developed a simple template-guided oxypolymerization strategy to synthesize polypyrrole(PPy)planar helixes as an efficient EM wave(EMW)absorber,and systematically investigated the morphology-dependent chirality,conductivity,and microwave absorption *** HCl concentration[HCl]varied from 0 to 2.0 M,the morphology evolved from planar helix to 3D cross-linking network structures,the conductivity increased from 0.0019 to 0.0302 S/cm,and the EM parameters peaked at[HCl]=0.5 *** to other absorbers,the PPy planar helix formed at[HCl]=0 M possessed wider absorption band(5.84 GHz),smaller matching thickness(1.6 mm),lower loading(25 wt.%),and intenser absorption(-48.17 dB).The reason lies in the strong attenuation capability,multiple resonances,multiple scattering,and good impedance matching generated by chiral PPy planar helixes with a distinctive helical configuration,doped heteroatoms(O,S),and a local conductive *** results suggest that PPy planar helixes offer great promise for fields such as chiral sensors,electronics,optics,chiral catalysis,and EMW absorption and shielding due to their distinctive morphology,tunable conductivity,and outstanding EMW absorption properties(EMWAPs).

关键词： PPy planar helix CTAB template assisted oxypolymerization strategy electromagnetic wave absorption performance absorption mechanism

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A comparative study of flow induced by 1D, 2D and 3D ultrasounds

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Science China(Technological Sciences) 2019年第7期62卷 1224-1231页

作者： wu wenhua ZHAI Wei ZHANG YiBao XI HengDong LIU HaiMan ZHANG Jian WEI BingBo Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China School of Aeronautics Northwestern Polytechnical University Xi'an 710072 China

The acoustic streaming which can facilitate the heat and mass transfer inside liquids is of great importance in ultrasonic processing. Most of previous investigations were mainly focused on the acoustic streaming induced by one dimensional(1 D)ultrasound. In this paper, the flow field generated by 1 D, 2 D and 3 D ultrasounds in a cubic box filled with water was investigated by numerical simulations. It is found that the jet flow emitted from the sound source is in the form of cylinder, vortex and wave,for 1 D, 2 D and 3 D ultrasounds, respectively. When the ultrasonic dimension is increased, the flow becomes much stronger in the vicinity of the sound source but little weaker at the box center. By comparing the patterns of the flow generated by the ultrasounds of different dimensions, we demonstrate that 3 D ultrasounds not only enhance the overall flow strength, but also effectively promote the uniformity of the flow and enlarge the size of vortices.

关键词： ultrasonic processing ultrasonic dimension acoustic streaming flow uniformity

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Performance improvement of optimization solutions by POD-based data mining

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Chinese Journal of Aeronautics 2019年第4期32卷 826-838页

作者： Yanhui DUAN wenhua wu Peihong ZHANG Fulin TONG Zhaolin FAN Guiyu ZHOU Jiaqi LUO Computational Aerodynamics Institute China Aerodynamics Research and Development Center School of Aeronautics and Astronautics Zhejiang University

The performance of an optimized aerodynamic shape is further improved by a second-step optimization using the design knowledge discovered by a data mining technique based on Proper Orthogonal Decomposition(POD) in the present study. Data generated in the first-step optimization by using evolution algorithms is saved as the source data, among which the superior data with improved objectives and maintained constraints is chosen. Only the geometry components of the superior data are picked out and used for constructing the snapshots of POD. Geometry characteristics of the superior data illustrated by POD bases are the design knowledge, by which the second-step optimization can be rapidly achieved. The optimization methods are demonstrated by redesigning a transonic compressor rotor blade, NASA Rotor 37, in the study to maximize the peak adiabatic efficiency, while maintaining the total pressure ratio and mass flow ***, the blade is redesigned by using a particle swarm optimization method, and the adiabatic efficiency is increased by 1.29%. Then, the second-step optimization is performed by using the design knowledge, and a 0.25% gain on the adiabatic efficiency is obtained. The results are presented and addressed in detail, demonstrating that geometry variations significantly change the pattern and strength of the shock wave in the blade passage. The former reduces the separation loss,while the latter reduces the shock loss, and both favor an increase of the adiabatic efficiency.

关键词： Aerodynamic shape optimization Computational fluid dynamics Data mining Particle swarm optimization Proper Orthogonal Decomposition Transonic flow Turbomachinery

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Identifying RNA Modifications by Direct RNA Sequencing Reveals Complexity of Epitranscriptomic Dynamics in Rice

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Genomics, Proteomics & Bioinformatics 2023年第4期21卷 788-804页

作者： Feng Yu Huanhuan Qi Li Gao Sen Luo Rebecca Njeri Damaris Yinggen Ke wenhua wu Pingfang Yang State Key Laboratory of Biocatalysis and Enzyme Engineering School of Life SciencesHubei UniversityWuhan 430062China

Transcriptome analysis based on high-throughput sequencing of a cDNA library has been widely applied to functional genomic ***,the cDNA dependence of most RNA sequencing techniques constrains their ability to detect base modifications on RNA,which is an important element for the post-transcriptional regulation of gene *** comprehensively profile the N^(6)-methyladenosine(m^(6)A)and N^(5)-methylcytosine(m5 C)modifications on RNA,direct RNA sequencing(DRS)using the latest Oxford Nanopore Technology was applied to analyze the transcriptome of six tissues in *** 94 million reads were generated,with an average length ranging from 619 nt to 1013 nt,and a total of 45,707 transcripts across 34,763 genes were *** profiles of transcripts at the isoform level were quantified among ***-wide mapping of m^(6)A and m5 C demonstrated that both modifications exhibited tissue-specific *** transcripts with m^(6)A modifications tended to be modified by m5 C,and the transcripts with modifications presented higher expression levels along with shorter poly(A)tails than transcripts without modifications,suggesting the complexity of gene expression *** Ontology analysis demonstrated that m^(6)A-and m5 C-modified transcripts were involved in central metabolic pathways related to the life cycle,with modifications on the target genes selected in a tissue-specific ***,most modified sites were located within quantitative trait loci that control important agronomic traits,highlighting the value of cloning functional *** results provide new insights into the expression regulation complexity and data resource of the transcriptome and epitranscriptome,improving our understanding of the rice genome.

关键词： Direct RNA sequencing Polyadenylated transcriptome N6-methyladenosine N5-methylcytosine Rice

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Surface Modification of Electrospun Poly(L-lactide)/Poly(ε-caprolactone)Fibrous Membranes by Plasma Treatment and Gelatin Immobilization

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Journal of Donghua University(English Edition) 2021年第3期38卷 193-198页

作者： SHI Tongna SHI Zhenjiang ZHU Bingjie wu wenhua National Demonstration Center for Experimental Materials Science and Engineering Education Donghua University Shanghai 201620 China

Biopolymer fibers have great potential for technical applications in *** surface properties of fibers are of importance in these *** this study,electrospun poly(L-lactide)(PLLA)/poly(ε-caprolactone)(PCL)membranes were modified by cold plasma treatment and coating gelatin to improve the surface hydrophilic *** morphologies of the fibers were observed by scanning electron microscopy(SEM).Atomic force microscopy(AFM)was employed to show the surface characteristics of the *** chemical feature of the fibrous membrane surfaces was examined by X-ray photoelectron spectroscopy(XPS).The surface wettability of the fibrous membrane was also characterized by water contact angle *** these results show that plasma treatment can have profound effects on the surface properties of fibrous membranes by changing their surface physical and chemical ***-PLLA/PCL membrane has great potential in applications of tissue engineering scaffolds.

关键词： surface property modification electrospun fiber plasma treatment chemical feature morphology wettability

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Effect of liquid-solid ratio on the morphology,structure,conductivity,and electromagnetic characteristics of iron particles

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Science China(Technological Sciences) 2011年第2期54卷 484-489页

作者： TONG GuoXiu HUA Qiao wu wenhua QIN MingYue LI LiangChao GONG PeiJun College of Chemistry and Life Sciences Zhejiang Normal University Jinhua 321004 China

Using a ball-milling technique,polymorphous iron particles were prepared by changing only the liquid-solid ratioλ.Effects of λon their morphology,structure,conductivity,and electromagnetic properties were *** results show that an increase ofλfrom 0 to 0.25 causes a nonlinear decrease of the conductivity in the ranges of 88.50-2.25 S cm-1 and a regular variation of the electromagnetic parameters,corresponding to the as-obtained iron *** is ascribed to a combination of the increased shape anisotropy and the decreased fresh surface with active atoms deriving from the weakened welding-on action and the enhanced micro-malleation action in the ball-milling ***,the iron flakes formed at wet-milling with λ=0.08-0.25 have lower conductivity,higher permittivity and permeability,and more excellent absorption property compared with the irregular iron particles obtained at dry-milling withλ=*** is a consequence of the synergistic effect of dielectric relaxation loss,exchange energy and conductance loss originating from the flake-shape *** indicates that the morphology,structure,conductivity,and electromagnetic properties of the products can be effectively controlled by changingλ.

关键词： iron flake liquid-solid ratio conductivity microwave electromagnetic property

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Effects of regional cerebral blood flow perfusion on learning and memory function and its molecular mechanism in rats

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Translational Neuroscience and Clinics 2016年第1期2卷 17-24页

作者： Cunli Xu wenhua wu Lingbin Kong Rehabilitation Medicine Center The First People’s Hospital of Jining Department of Neurology The Second People’s Hospital of Jining Shandong Institute of Behavioral Medical Science Jining Medical College

Objective:To study the effects of regional cerebral blood flow(r CBF)perfusion on learning and memory function in special brain areas and its molecular mechanism in ***:Sixty-four adult male healthy Sprague-Dawley(SD)rats were randomly divided into two groups:A false operation group and an operation *** false operation group was randomly divided into four subgroups(A_0,B_0,C_0,and D_0)and the operation group was randomly divided into four subgroups(A,B,C,and D),with eight rats in each *** operation group underwent bilateral common carotid artery permanent ligation,while the other group only underwent a skin incision without the bilateral common carotid artery permanent *** memory function of rats in each subgroup was measured using a Y-maze at 4 h,8 h,24 h,and 3 days after *** r CBF in the right frontal lobe and hippocampus was detected using the Periflux PF model laser Doppler flowmetry and c-fos,c-jun,Bcl-2,and Bax protein expression in the right frontal lobe and hippocampus was measured using ***:The r CBF in the right frontal lobule division and right hippocampus division was significantly lower in the operation group than in the false operation group(P<0.05).The error number(EN),time to reach the target,and total reaction time(TRT)for the learning index using the Y-type labyrinth test in the operation group were significantly higher than that in the false operation group(P<0.05);however,the active avoid rate in the operation group was significantly lower than that of the false operation *** of c-fos and c-jun as well as the average absorbency in the right frontal lobule division and right hippocampus division in the operation group were significantly higher than those in the false operation group(P<0.05).The number of Bax and Bcl-2-positive cells was significantly higher in the operation group,and the expression ratio of Bax/Bcl-2 in the operation group was significantly higher t

关键词： regional cerebral blood flow learning and memory function correlation molecular mechanism

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