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Effect of Incoming Vortex on Secondary Flows in Turbine Cascades with Planar and Non-Axisymmetric Endwall

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Journal of Thermal Science 2024年第1期33卷 138-157页

作者： CAO Zhiyuan WANG Chuxuan SONG Zhigao GAO Xi ZHAO Wei liu bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an 710072China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100080China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100080China

Non-Axisymmetric Endwall Profiling(NAEP) is commonly utilized in turbines to eliminate secondary flows.Nevertheless,most of the NAEP methods consider a single-blade row environment without incorporating the effect of the stage environment.This paper aims to investigate the influence mechanism of the incoming vortex on the endwall secondary flow structures of NAEP in a highly loaded turbine cascade.To model the incoming vortex in a stage environment,this study considers a half-delta wing as the vortex generator at the upstream of the turbine cascade.The NAEP is then carried out for a highly loaded turbine cascade with an in-house numerical optimization design platform subject to no incoming vortex.Numerical simulation is also carried out under the influence of the incoming vortex for the turbine cascades with both planar and non-axisymmetric endwall.This paper furthers investigated the pitchwise effect of the incoming vortex on the near endwall secondary flow.The results indicate that the NAEP effectively improves the endwall secondary flow of the turbine cascade,where the total pressure loss coefficient and the secondary kinetic energy(SKE) are reduced by 7.3%,and 45.7%,respectively.It is further seen that with the incoming vortex,the NAEP achieves a considerable control effect on the endwall secondary flow of the turbine cascade.With incoming vortex,the NAEP can still achieve considerable control effect on the endwall secondary flow of the turbine cascade;the averaged reductions of loss coefficient and SKE are 7.8% and 14.2%,respectively.Under some pitchwise locations,incoming vortex can suppress the convection of cross-passage flow toward the suction corner greatly and reduce the loss coefficient of the baseline cascade.The incoming vortex at 4/7 pitch impinged right at the blade leading edge,leading to the generation of low-momentum fluid,which increased the size and the strength of the horseshoe vortex.Under all the pitchwise locations,NAEP can suppress the secondary vortices,e.g.,the passage vortex and the c

关键词： non-axisymmetric endwall secondary flow incoming vortex passage vortex stage environment

Organic Matter Accumulation in the Upper Permian Dalong Formation from the Lower Yangtze Region,South China

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 150-167页

作者： FANG Chaogang ZHANG Chengcheng MENG Guixi XU Jinlong XU Naicen LI Hualing liu Mu liu bo Institute of International Rivers and Eco-Security Yunnan UniversityKunming 650500China Nanjing Center China Geological SurveyNanjing 210016China Exploration Research Institute Anhui Provincial Bureau of Coal GeologyHefei 230088China China United Coalbed Methane Corporation Ltd. Beijing 100015China Geological Survey of Anhui Province Hefei 230001China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

The Late Permian was marked by a series of important geological events and widespread organic-rich black shale depositions,acting as important unconventional hydrocarbon source rocks.However,the mechanism of organic matter(OM)enrichment throughout this period is still controversial.Based on geochemical data,the marine redox conditions,paleogeographic and hydrographic environment,primary productivity,volcanism,and terrigenous input during the Late Permian in the Lower Yangtze region have been studied from the Putaoling section,Chaohu,to provide new insights into OM accumulation.Five Phases are distinguished based on the TOC and environmental variations.In Phase I,anoxic conditions driven by water restriction enhanced OM preservation.In Phase II,euxinic and cycling hydrological environments were the two most substantial controlling factors for the massive OM deposition.During Phase III,intensified terrestrial input potentially diluted the OM in sediment and the presence of oxygen in bottom water weakened the preservation condition.Phase IV was characterized by a relatively higher abundance of mercury(Hg)and TOC(peak at 16.98 wt%),indicating that enhanced volcanism potentially stimulated higher productivity and a euxinic environment.In Phase V,extremely lean OM was preserved as a result of terrestrial dilutions and decreasing primary productivity.Phases I,II and IV are characterized as the most prominent OM-rich zones due to the effective interactions of the controlling factors,namely paleogeographic,hydrographic environment,volcanism,and redox conditions.

关键词： geochemistry redox condition primary productivity OM accumulation Lopingian/Changhsingian Lower Yangtze region

An electrically controlled tunable photonic crystal filter based on thin-film lithium niobate

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Optoelectronics Letters 2024年第4期20卷 200-204页

作者： WANG Yifan YAO Yuan ZHANG Hao liu bo DUAN Shaoxiang LIN Wei Institute of Modern Optics College of Electronic Information and Optical EngineeringNankai UniversityTianjin 300350China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Nankai UniversityTianjin 300350China Southern Marine Science and Engineering Guangdong Laboratory Zhuhai 519000China Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Nankai UniversityTianjin 300350China

In this paper,we present an electrically controlled tunable narrowband filter based on a thin-film lithium niobate two-dimensional(2D)photonic crystal.The filter incorporates a photonic crystal microcavity structure within the straight waveguide,enabling electronic tuning of the transmitted wavelength through added electrode structures.The optimized microcavity filter design achieves a balance between high transmission rate and quality factor,with a transmission center wavelength of 1551.6 nm,peak transmission rate of 96.1%,and quality factor of 5054.Moreover,the filter can shift the central wavelength of the transmission spectrum by applying voltage to the electrodes,with a tuning sensitivity of 13.8 pm/V.The proposed tunable filter adopts a simple-to-fabricate air-hole structure and boasts a compact size(length:11.57μm,width:5.27μm,area:60.97μm^(2)),making it highly suitable for large-scale integration.These features make the filter promising for broad applications in the fields of photonic integration and optical communication.

关键词： tunable tuning waveguide

A strategy based on water soluble coal tar pitches to construct MnO_(2)@C composite materials with high electrochemical performance

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Science China(Technological Sciences) 2024年第1期67卷 311-320页

作者： liu bo WANG Kun GUO ZhaoQi HAN BeiBei XU GuiYing JU DongYing AN BaiGang LI YongCheng NI ZhenYong ZHOU WeiMin Key Laboratory of Energy Materials and Electrochemistry Research Liaoning Province University of Science and Technology LiaoningAnshan 114051China Advanced Science Research Laboratory Saitama Institute of TechnologyFusaiji 1690Japan Liaoning Starry Sky Sodium Battery Co. Ltd.Anshan 114051China Sinosteel Anshan Research Institute of Thermo-Energy Co. Ltd.Anshan 114051China State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikou 570228China Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China

The water soluble coal tar pitches(WS-CTPs)were successfully prepared and used to construct the MnO_(2)@C composite materials by a hydrothermal method.It is interestingly observed that the structures and morphologies of MnO_(2)@C materials can be controlled by controlling the dosages of WS-CTPs and KMnO4.Meanwhile,it is aware that MnO_(2)exists in the MnO_(2)@C materials in an amorphous state.Compared with MnO_(2),MnO_(2)@C materials output a remarkable improvement in electrochemical performance.For instance,MnO_(2)@C-0.3 shows the storage capacity at 965.7 mA h g^(−1)after 300 cycles at a current density of 0.1 A g^(−1).In addition,after 600 cycles at a current density of 1.0 A g^(−1),the storage capacity of MnO_(2)@C-0.3 still keeps 450.3 mA h g^(−1),indicating that MnO_(2)@C-0.3 owns tremendous cycle stability at a high current density.In view of the fact that the coal tar pitches possess great cost advantages,the strategy of using WS-CTPs as a carbon source to cover the metal oxides is a competitive way to expand the application of metal oxides in the fabrication of electrodes of LIBs.

关键词： water soluble coal tar pitches MnO_(2) composite materials lithium ion batteries(LIBs) energy storage systems(ESSs) coal tar pitches

Mg(NO_(3))_(2)·6H_(2O)-Assisted insitu-Fabrication of Tea Residual Biochar for Ultra-Fast and High Adsorption of Rhodamine B

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Wuhan University Journal of Natural Sciences 2024年第2期29卷 165-176页

作者： HU Dandan XUE Yangfan liu bo WU Yongjuan LI Zichen School of Chemistry&Chemical Engineering Shaanxi Xueqian Normal UniversityXi'an 710100ShaanxiChina Safe College Xi􀆳an University of Science and TechnologyXi'an 710054ShaanxiChina

In this work,porous biochar(MN-TRB_(750))was fabricated via direct pyrolysis of tea residue(TR)and Mg(NO_(3))_(2)·6H_(2)O(MN).The as-synthesized MN-TRB_(750) reached a specific surface area of 839.54 m^(2)·g^(-1)and an average pore size of 3.75 nm with multi-level pore architecture.MN decreased TR's carbonization temperature and promoted the aromatics extent,pore structure for the frizzly flake-like biochar.Rhodamine B(RhB)was chosen as the adsorbate to explore the removal performance of organic dyes in this study.The results indicated that the maximum adsorption capacity of RhB on MN-TRB_(750) at 20℃ is up to 809.0 mg·g^(-1)with isotherms fitted well to Freundlich and Dubinin-Radushkevic models.The adsorption kinetics followed pseudo-second-order and Elovich models with an equilibrium adsorption capacity of 757.6 mg·g^(-1)as the initial concentration of RhB is 260 mg·L^(-1).High pore filling,hydrogen bond,π-πinteraction determined the adsorption of RhB onto MN-TRB850 through a multi-active center and exothermic chemical sorption process.

关键词： Mg(NO_(3))_(2)·6H_(2)O porous biochar mechanism rhodamine B adsorption

Design of improved error-rate sliding window decoder for SC-LDPC codes: reliable termination and channel value reuse

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Optoelectronics Letters 2024年

作者： JIA Xishan LI Jining YAO Yuan WANG Yifan liu bo XU Degang School of Precision Instruments and Opto-electronics Engineering Tianjin University Key Laboratory of Optoelectronics Information Technology (Ministry of Education) Tianjin University Institute of Modern Optics College of Electronic Information and Optical Engineering Nankai University Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology

In this paper， an improved error-rate sliding window decoder is proposed for spatially coupled low-density parity-check (SC-LDPC) codes. For the conventional sliding window decoder， the message retention mechanism causes unreliable messages along the edges of belief propagation (BP) decoding in the current window to be kept for subsequent window decoding. To improve the reliability of the retained messages during the window transition， a reliable termination method is embedded， where the retained messages undergo more reliable parity checks. Additionally， decoding failure is unavoidable and even causes error propagation when the number of errors exceeds the error-correcting capability of the window. To mitigate this problem， a channel value reuse mechanism is designed， where the received channel values are utilized to reinitialize the window. Furthermore， considering the complexity and performance of decoding， a feasible sliding optimized-window decoding (SOWD) scheme is introduced. Finally， simulation results confirm the superior performance of the proposed SOWD scheme in both the waterfall and error floor regions. This work has great potential in the applications of wireless optical communication and fiber optic communication.

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Exploration of cardiac rehabilitation nursing for elderly patients with myocardial infarction based on individualized cardiac rehabilitation

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World Journal of Clinical Cases 2024年第2期12卷 256-266页

作者： Hua-Ning liu bo Gao Department of Geriatrics General Hospital of the YangTze River ShippingWuhan Brain HospitalWuhan 430015Hubei ProvinceChina Department of Cardiology Suizhou Central HospitalAffiliated Hospital of Hubei University of MedicineSuizhou 441300Hubei ProvinceChina

BACKGROUND Myocardial infarction is a high-risk condition prevalent among the elderly population,often leading to adverse clinical manifestations such as reduced cardiopulmonary function,anxiety,and depression post-surgery.Consequently,cardiac rehabilitation holds immense importance in mitigating these complications.AIM To evaluate the effect of individualized cardiac rehabilitation on blood pressure variability(BPV)and baroreflex sensitivity(BRS)in elderly patients with myocardial infarction.METHODS A cohort of 74 elderly patients diagnosed with myocardial infarction and admitted to our hospital between January 2021 and January 2022 were subjected to random selection.Subsequently,all patients were divided into two groups,namely the research group(n=37)and the control group(n=37),utilizing the number table method.The control group received conventional drug treatment and nursing guidance intervention,while the study group underwent individualized cardiac rehabilitation in addition to the interventions received by the control group.All patients were continuously intervened for 12 wk,and the BPV of these two groups in the 1st wk(T0),the 4th wk(T1)and the 12th wk(T2)were compared,BRS,changes in cardiopulmonary function measures,and adverse cardiovascular events.RESULTS Of 24 h diastolic BPV,24 h systolic BPV,carbon dioxide ventilation equivalent slope of the research group were lower than those of the control group at T1 and T2,BRS,peak heart rate and systolic blood pressure product,1 min heart rate recovery were higher than those of the control group,and the incidence of adverse events in the research group was lower than that of the control group,the difference was statistically significant(P<0.05).CONCLUSION In this study,we found that after individualized cardiac rehabilitation in elderly patients with myocardial infarction,BPV and BRS can be effectively improved,cardiac function is significantly enhanced,and a better prognosis is obtained.

关键词： Individualized cardiac rehabilitation Myocardial infarction Variability in blood pressure Baroreflex sensitivity

Recursive Filtering for Stochastic Systems With Filter-and-Forward Successive Relays

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1202-1212页

作者： Hailong Tan bo Shen Qi Li Hongjian liu School of Mathematics-Physics and Finance Anhui Polytechnic UniversityWuhu 241000China Anhui Future Technology Research Institute Anhui Polytechnic UniversityWuhu 241000China College of Information Science and Technology Donghua UniversityShanghai 201620China Engineering Research Center of Digitalized Textile and Fashion Technology Ministry of EducationShanghai 201620China School of Information Science and Engineering Hangzhou Normal UniversityHangzhou 311121China

In this paper,the recursive filtering problem is considered for stochastic systems over filter-and-forward successive relay(FFSR)networks.An FFSR is located between the sensor and the remote filter to forward the measurement.In the successive relay,two cooperative relay nodes are adopted to forward the signals alternatively,thereby existing switching characteristics and inter-relay interferences(IRI).Since the filter-and-forward scheme is employed,the signal received by the relay is retransmitted after it passes through a linear filter.The objective of the paper is to concurrently design optimal recursive filters for FFSR and stochastic systems against switching characteristics and IRI of relays.First,a uniform measurement model is proposed by analyzing the transmission mechanism of FFSR.Then,novel filter structures with switching parameters are constructed for both FFSR and stochastic systems.With the help of the inductive method,filtering error covariances are presented in the form of coupled difference equations.Next,the desired filter gain matrices are further obtained by minimizing the trace of filtering error covariances.Moreover,the stability performance of the filtering algorithm is analyzed where the uniform bound is guaranteed on the filtering error covariance.Finally,the effectiveness of the proposed filtering method over FFSR is verified by a three-order resistance-inductance-capacitance circuit system.

关键词： filtering successive stochastic

Tracking Regulatory Mechanism of Trace Fe on Graphene Electromagnetic Wave Absorption

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Nano-Micro Letters 2024年第4期16卷 79-96页

作者： Kaili Zhang Yuhao liu Yanan liu Yuefeng Yan Guansheng Ma bo Zhong Renchao Che Xiaoxiao Huang School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001People’s Republic of China MIIT Key Laboratory of Advanced Structural‑Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001People’s Republic of China School of Materials Science and Engineering Harbin Institute of Technology at WeihaiWeihai 264209People’s Republic of China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative MaterialsFudan UniversityShanghai 200438People’s Republic of China

Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.

关键词： Reduced graphene oxide Fe nanosheets Dielectric loss Electromagnetic wave absorption