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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

Elusive workers are more likely to differentiate into replacement reproductives than aggressive workers in a lower termite

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Current Zoology 2023年第3期69卷 332-338页

作者： Zhuang-Dong Bai Chong-Yang Shi David Sillam-Dusses Rui-Wu Wang School of Ecology and Environment Northwestern Polytechnical UniversityXi'an 710072China Laboratory of Experimental and Comparative Ethology LEECUR 4443University Sorbonne Paris NordVilletaneuseFrance

One of the most intriguing questions in eusocial insects is to understand how the overt reproductive conflict in the colony appears limited when queens or kings are senescent or lost because the morphologically similar individuals in the colony are reproductively totipotent.Whether there are some individuals who preferentially differentiate into replacement reproductives or not has received little attention.The consistent individual behavioral differences(also termed“animal personality”)of individuals from the colony can shape cunningly their task and consequently affect the colony fitness but have been rarely investigated in eusocial insects.Here,we used the termite Reticulitermes labralis to investigate if variations in individual personalities(elusiveness and aggressiveness)may predict which individuals will perform reproductive differentiation within colonies.We observed that when we separately reared elusive and aggressive workers,elusive workers differentiate into reproductives significantly earlier than aggressive workers.When we reared them together in the proportions 12:3,10:5,and 8:7(aggressive workers:elusive workers),the first reproductives mostly differentiated from the elusive workers,and the reproductives differentiated from the elusive workers significantly earlier than from aggressive workers.Furthermore,we found that the number of workers participating in reproductive differentiation was significantly lower in the groups of both types of workers than in groups containing only elusive workers.Our results demonstrate that the elusiveness trait was a strong predictor of workers’differentiation into replacement reproductives in R.labralis.Moreover,our results suggest that individual personalities within the insect society could play a key role in resolving the overt reproductive conflict.

关键词： consistent individual behavioral differences reproductive conflict reproductive differentiation,Reticulitermes labralis termite

3D Printing of Next-generation Electrochemical Energy Storage Devices: from Multiscale to Multimaterial

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Energy & Environmental Materials 2022年第2期5卷 427-438页

作者： xi Xu Yong Hao Tan Jun Ding Cao Guan Institute of Flexible Electronics Xi’an Key Laboratory of Flexible ElectronicsNorthwestern Polytechnical UniversityXi’an 710072China Department of Materials Science and Engineering Faculty of EngineeringNational University of SingaporeSingapore 117574Singapore NUS graduate School for Integrative Sciences and Engineering National University of SingaporeSingapore 119077Singapore

The increasing energy requirements to power the modern world has driven active research into more advanced electrochemical energy storage devices(EESD)with both high energy densities and power densities.Wide range of newly discovered materials with promising electrochemical properties has shown great potential for next-generation devices,but their performance is normally associated with contradicting demands of thin electrodes and high mass loading that can be hardly achieved for practical applications.Design of three-dimensional(3D)porous electrodes can increase the mass loading while maintaining the effective charge transport even with thick electrodes,which has proven to be efficient to overcome the limitations.3D structures have also been demonstrated excellent structural stability to withstand strong strains and stresses generated during charge/discharge cycle.3D printing,which can fabricate various delicate and complex structural designs,thus offering brand-new opportunities for the rational design and facile construction of next-generation EESDs.The recent developments in 3D printing of next-generation EESDs with high performance are reviewed.Advanced/multiscale electrode structures,such as hierarchically porous structure that can be constructed via high-resolution 3D printing or with post-treatment,are further emphasized.The ability of current 3D printing techniques to fulfill multimaterial printing to fulfill simple packaging will be covered.

关键词： 3d printing electrochemical energy storage devices multimaterial multiscale

MoS_(2)-Decorated/Integrated Carbon Fiber:Phase Engineering Well-Regulated Microwave Absorber

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Nano-Micro Letters 2021年第7期13卷 173-187页

作者： Jing Yan Ying Huang xiangyong Zhang xin Gong Chen Chen Guangdi Nie Xudong Liu Panbo Liu MOE Key Laboratory of Material Physics and Chemistry Under Extraodinary Conditions School of Chemistry and Chemical Engineering Ministry of EducationNorthwestern Polytechnical UniversityXi’an 710072People’s Republic of China School of Materials Science and Engineering Central South UniversityChangsha 410083People’s Republic of China Institute of Flexible Electronics Northwestern Polytechnical UniversityXi’an 710072People’s Republic of China Industrial Research Institute of Nonwovens and Technical Textiles College of Textiles and ClothingQingdao UniversityQingdao 266071People’s Republic of China

Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of different phases on the EMW absorbing performance,such as 1T and 2H phase,is still not studied.In this work,micro-1T/2H MoS_(2) is achieved via a facile one-step hydrother-mal route,in which the 1T phase is induced by the intercalation of guest molecules and ions.The EMW absorption mechanism of single MoS_(2) is revealed by presenting a comparative study between 1T/2H MoS_(2) and 2H MoS_(2).As a result,1T/2H MoS_(2) with the matrix loading of 15%exhibits excellent microwave absorption property than 2H MoS_(2).Furthermore,taking the advantage of 1T/2H MoS_(2),a flexible EMW absorbers that ultrathin 1T/2H MoS_(2)grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%.This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.

关键词： Phase engineering Electromagnetic wave absorber 1T/2H MoS_(2) 2H MoS_(2) Flexible film

Hierarchically Multifunctional Polyimide Composite Films with Strongly Enhanced Thermal Conductivity

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Nano-Micro Letters 2022年第2期14卷 94-106页

作者： Yongqiang Guo Hua Qiu Kunpeng Ruan Yali Zhang Junwei Gu Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072ShaanxiPeople’s Republic of China

The development of lightweight and integration for electronics requires flexible films with high thermal conductivity and electromagnetic interference(EMI) shielding to overcome heat accumulation and electromagnetic radiation pollution.Herein,the hierarchical design and assembly strategy was adopted to fabricate hierarchically multifunctional polyimide composite films,with graphene oxide/expanded graphite(GO/EG) as the top thermally conductive and EMI shielding layer,Fe_(3)O_(4)/polyimide(Fe_(3)O_(4)/PI) as the middle EMI shielding enhancement layer and electrospun PI fibers as the substrate layer for mechanical improvement.PI composite films with 61.0 wt% of GO/EG and 23.8 wt% of Fe_(3)O_(4)/PI exhibits high in-plane thermal conductivity coefficient(95.40 W(m K)^(-1)),excellent EMI shielding effectiveness(34.0 dB),good tensile strength(93.6 MPa) and fast electric-heating response(5 s).The test in the central processing unit verifies PI composite films present broad application prospects in electronics fields.

关键词： EMI shielding Flexible films Polyimide Thermal conductivity

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细胞间线粒体成分转移触发缺血性心肌纤维化

Science Bulletin 2023年第16期68卷 1784-1799,M0004页

作者：张婵郝好王一石穆楠姜文华张子绘殷玥余璐张家毓马恒 xi’an Key Laboratory of Stem Cell and Regenerative Medicine Institute of Medical ResearchNorthwestern Polytechnical UniversityXi’an 710072China Department of Physiology and Pathophysiology School of Basic MedicineFourth Military Medical UniversityXi’an 710032China Department of Cardiology and Shanghai Institute of Precision Medicine Ninth People’s HospitalShanghai Jiao Tong University School of MedicineShanghai 211125China Department of Pathology Xijing HospitalFourth Military Medical UniversityXi’an 710032China

心肌纤维化是引发心源性猝死的重要原因.心肌缺血/再灌注(MI/R)损伤可导致心肌细胞损伤甚至死亡,而成纤维细胞却出现激活并导致纤维化.目前,导致这一矛盾现象的细胞间通讯机制仍不清楚.小细胞外囊泡(small extracellular vesicles,sEVs... 详细信息

心肌纤维化是引发心源性猝死的重要原因.心肌缺血/再灌注(MI/R)损伤可导致心肌细胞损伤甚至死亡,而成纤维细胞却出现激活并导致纤维化.目前,导致这一矛盾现象的细胞间通讯机制仍不清楚.小细胞外囊泡(small extracellular vesicles,sEVs)在细胞间通讯中起重要作用.但是,sEVs是否介导以及如何介导MI/R后心肌细胞和成纤维细胞间的通讯尚不清楚.本研究通过在体MI/R模型和细胞学实验发现,MI/R损伤情况下存在一种心肌细胞来源的sEV(Myo-sEV^(I/R)),其内容物富含线粒体成分.Myo-sEV^(I/R)被成纤维细胞摄取并触发纤维化.通过生物信息学筛选和实验验证,新发现Ambra1是Myo-sEV^(I/R)中的关键组分和潜在标志物.并且证实,Ambra1+-Myo-sEVs的释放是由MI/R损伤后心肌细胞的分泌型自噬所驱动,而不是经典的降解型自噬.在缺血和缺血周边区域,Ambra1^(+)-Myo-sEVs被成纤维细胞内吞导致跨细胞线粒体成分传递;线粒体DNA(mtDNA)激活cGAS-STING通路,促进成纤维细胞的活化和增殖.此外,数据显示,Ambral定位于Myo-sEV^(I/R)表面,心脏特异性的下调Ambral可抑制Ambral^(+)-Myo-sEVs的释放和成纤维细胞摄取,有效抑制缺血后心肌纤维化.本研究新证实了心肌分泌型自噬可介导缺血后心肌纤维化发生过程中的细胞间通讯.Ambral是Myo-sEVs的潜在标志物和特征分子,并具有重要的生物活性.本研究为缺血后心脏重塑提供了新的治疗靶点.

关键词：心肌缺血/再灌注心源性猝死细胞间通讯成纤维细胞细胞线粒体细胞学实验心肌细胞矛盾现象

Structure-Enhanced Mechanically Robust Graphite Foam with Ultrahigh MnO_(2) Loading for Supercapacitors

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Research 2020年第1期2020卷 1285-1294页

作者： Qinghe Cao Junjie Du xiaowan Tang xi Xu Longsheng Huang Dongming Cai Xu Long Xuewen Wang Jun Ding Cao Guan Wei Huang Frontiers Science Center for Flexible Electronics Institute of Flexible ElectronicsNorthwestern Polytechnical UniversityXi’an 710072China Department of Materials Science and Engineering National University of Singapore9 Engineering Drive 1SingaporeSingapore 117576 College of Chemical Engineering Hubei UniversityWuhan 430062China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China

With the fast bloom of flexible electronics and green vehicles,it is vitally important to rationally design and facilely construct customized functional materials with excellent mechanical properties as well as high electrochemical performance.Herein,by utilizing two modern industrial techniques,digital light processing(DLP)and chemical vapor deposition(CVD),a unique 3D hollow graphite foam(HGF)is demonstrated,which shows a periodic porous structure and robust mechanical properties.Finite element analysis(FEA)results confirm that the properly designed gyroidal porous structure provides a uniform stress area and mitigates potential structural failure caused by stress concentrations.A typical HGF can show a high Young’s modulus of 3.18 MPa at a low density of 48.2 mg cm^(-3).The porous HGF is further covered by active MnO_(2) material with a high mass loading of 28.2 mg cm^(-2)(141 mg cm^(-3)),and the MnO_(2)/HGF electrode still achieves a satisfactory specific capacitance of 260 F g^(-1),corresponding to a high areal capacitance of 7.35 F cm^(-2) and a high volumetric capacitance of 36.75 F cm^(-3).Furthermore,the assembled quasi-solid-state asymmetric supercapacitor also shows remarkable mechanical properties as well as electrochemical performance.

关键词： porous capacitance utilizing

Electrospun Nanofibers for New Generation Flexible Energy Storage

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Energy & Environmental Materials 2021年第4期4卷 502-521页

作者： Yonghui Yan xiangye Liu Jing Yan Cao Guan John Wang Frontiers Science Center for Flexible Electronics Institute of Flexible ElectronicsNorthwestern Polytechnical UniversityXi’an 710072China Department of Materials Science and Engineering National University of SingaporeSingapore 117574Singapore

As one of the essential components for flexible electronics,flexible electrochemical energy storage(EES)has garnered extensive interests at all levels of materials,devices,and systems.The successful implementation of high-performance flexible EES devices relies on exploring of suitable electrode/electrolyte materials that have both superior electrochemical and mechanical properties.For this function,one-dimensional electrospun nanofibers have emerged as a class of promising building blocks for the key components of flexible EES devices.In this overview,the fundamental principles and technical advances of electrospinning are examined,for both their successes and challenges in controllable fabrication of nanofibers with the desirable chemical compositions,micro/meso-/nanostructures,and therefore resultant properties.The advances in applications of electrospun nanofibers for various key flexible EES devices are critically looked into,including those in supercapacitors,metal-ion batteries,and metal-air batteries.The existing challenges and prospects of these electrospun nanofiber-based flexible EES are discussed,aiming to inspire continued efforts in developing the optimal high-performance and low cost flexible EES devices for long-awaited practical applications.

关键词： 1D nanofibers electrochemical energy storage electrospinning flexible electronics

Kinetics process for structure-engineered integrated gradient porous paper-based supercapacitors with boosted electrochemical performance

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Nano Research 2023年第7期16卷 9471-9479页

作者： Chuanyin xiong Yongkang Zhang Jiayu Xu Weihua Dang Xuhui Sun Meng An Yonghao Ni Junjie Mao College of Bioresources Chemical&Materials Engineering Shaanxi University of Science and TechnologyXi’an 710021China College of Mechanical and Electrical Engineering Shaanxi University of Science and TechnologyXi’an 710021China university of New Brunswick Limerick Pulp&Paper CtrFrederictonNB E3B 5A3Canada College of Chemistry and Materials Science Anhui Normal UniversityWuhu 241000China

Due to their rich and adjustable porous network structure,paper-based functional materials have become a research hotspot in the field of energy storage.However,reasonably designing and making full use of the rich pore structure of paper-based materials to improve the electrochemical performance of paper-based energy storage devices still faces many challenges.Herein,we propose a structure engineering technique to develop a conductive integrated gradient porous paper-based(CIGPP)supercapacitor,and the kinetics process for the influence of gradient holes on the electrochemical performance of the CIGPP is investigated through experimental tests and COMSOL simulations.All results indicate that the gradient holes endow the CIGPP with an enhanced electrochemical performance.Specifically,the CIGPP shows a significant improvement in the specific capacitance,displays rich frequency response characteristics for electrolyte ions,and exhibits a good rate performance.Also,the CIGPP supercapacitor exhibits a low self-discharge and maintains a stable electrochemical performance in different electrolyte environments because of gradient holes.More importantly,when the CIGPP is used as a substrate to fabricate a CIGPP-PANI hybrid,it still maintains good electrochemical properties.In addition,the CIGPP supercapacitor also shows excellent stability and sensitivity for monitoring human motion and deaf-mute voicing,showing potential application prospects.This study provides a reference and feasible way for the design of structure-engineered integrated paper-based energy storage devices with outstanding comprehensive electrochemical performance.

关键词： conductive gradient porous paper electrochemical performance COMSOL simulations supercapacitor sensor