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Effect of kerosene injection states on mixing and combustion characteristics in a cavity-based supersonic combustor

Chinese Journal of Aeronautics 2024年第4期37卷 308-320页

作者： Xu LIU Peibo LI Fei LI Hongbo WANG Mingbo SUN Chao WANG Yixin YANG Dapeng XIONG Yanan WANG science and technology on scramjet laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China

It has been found that the static pressure distribution along the axial direction of liquid kerosene is lower than that of the gaseous kerosene under the same flow condition and overall equivalent ratio from previous studies.To further investigate this phenomenon,a compressible two-phase parallel simulation method is utilized to analyze the mixing and combustion characteristics of gaseous and liquid kerosene jets in a cavity-based supersonic combustor.The numerical results are consistent with the experiments and demonstrate that gaseous injection leads to a cavity shear layer that dives deeper into the cavity,forming two recirculation zones in the front and rear of the cavity.In contrast,the cavity shear layer is closer to the mainstream during liquid injection,and only a large recirculation zone is formed in the rear of the cavity.As a result of the cavity shear layer and the recirculating flow,the fuel vapor of gaseous injection accumulates in the front of the cavity,while for the liquid injection,the fuel vapor disperses in the cavity,cavity shear layer,and the region above,and the rear of the cavity has a higher fuel vapor concentration than the front.This unique fuel distribution causes the combustion area to be concentrated in the cavity during the gaseous injection but dispersed inside and downstream of the cavity during the liquid injection.As a result,forming a thermal throat under the same conditions is more challenging during liquid injection,and the generated static pressure distribution is lower than that during the gaseous injection.

关键词： Gaseous injection Liquid injection Mixing process Combustion Supersonic flow

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后缘开槽型超燃冲压发动机凹腔燃烧室及其促燃特性实验研究

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Acta Mechanica Sinica 2024年第1期40卷 74-84页

作者：张林乔玮梁剑寒王翼丁猛杨雷超孙明波 science and technology on scramjet laboratory National University of Defense TechnologyChangsha 410073China

为了改善传统的二维梯形凹腔在促进混合和燃烧方面的效果,本文提出了一种在凹腔后缘设置开槽的三维凹腔,并在超声速模型燃烧室中进行了研究.在直连式实验台上开展实验,对传统的二维梯形凹腔(基线)和后缘开槽凹腔进行了对比.结果表明,后... 详细信息

为了改善传统的二维梯形凹腔在促进混合和燃烧方面的效果,本文提出了一种在凹腔后缘设置开槽的三维凹腔,并在超声速模型燃烧室中进行了研究.在直连式实验台上开展实验,对传统的二维梯形凹腔(基线)和后缘开槽凹腔进行了对比.结果表明,后缘开槽凹腔增强了沿燃烧室的燃烧。具体而言,凹腔附近的压力在燃料喷注压力较低时增加6.1%,在燃料喷注压力较高时增加12.7%.基于准一维分析,后缘开槽凹腔的燃烧效率提高了20%以上。对于后缘开槽凹腔,燃烧面积和火焰基底位置受喷注压力的影响小于基线情况.与此同时,后缘开槽凹腔的火焰稳定能力较基线构型更优。凹腔交换面积增加、长深比增大以及开槽诱导的横向流动和流向涡可能是增强混合和燃烧的主要原因.

关键词：燃烧面积横向流动超燃冲压发动机火焰稳定准一维凹腔燃烧效率

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Topological magnetoelectric response in ferromagnetic axion insulators

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National science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen Institute for Quantum science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key laboratory for Computational science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological phenomena.However,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface states.Here,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the TME.In the designed triangular prism geometry,all the surface states are magnetically gapped.Under a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in parallel.Thus,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric field.Our work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

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Printable,flexible ceramic fiber paper based on electrospinning

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Rare Metals 2024年第6期43卷 2739-2746页

作者： Yong-Shuai Xie Yuan Cheng Yang Lyu Rui Li Jie-Cai Han National Key laboratory of science and technology on Advanced Composites in Special Environments Harbin Institute of Technology State Key laboratory of Intelligent Manufacturing Equipment and technology Huazhong University of Science and Technology

Based on the fact that it is challenging for the polymer flexible circuit substrates to meet the requirements of serving in high-temperature environments,this work proposed the idea of using printable ceramic fiber paper as a high-temperature flexible circuit substrate.A ceramic fiber paper with all ceramic components had been developed via electrospinning,solving the problems of low strength and severe strength drop at high temperatures of traditional ceramic fiber paper.The tensile strength of the prepared ceramic fiber paper is 2.63 MPa,and the reliable service temperature is 1200℃.Its bulk density is about 1.5 times that of traditional ceramic fiber paper.It can be printed with patterns by commercial inkjet printers like ordinary printing paper and has excellent printability.The feasibility of ceramic fiber paper as a flexible circuit substrate was verified by constructing a simple circuit.When the fiber paper is significantly bent,the circuit still forms a complete path,which proves that it has a strong application potential for high-temperature flexible circuit substrate and is expected to promote the development of flexible electronic devices serving at extreme high-temperature environments.

关键词： Ceramic fiber paper High temperature Inkjet printing Flexible electronic

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Polaron interfacial entropy as a route to high thermoelectric performance in DAE-doped PEDOT:PSS films

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National science Review 2024年第3期11卷 259-270页

作者： Jiajia Zhang Caichao Ye Genwang Wei Liang Guo Yuhang Cai Zhi Li Xinzhi Wu Fangyi Sun Qikai Li Yupeng Wang Huan Li Yuchen Li Shuaihua Wang Wei Xu Xuefeng Guo Wenqing Zhang Weishu Liu Department of Materials science and Engineering Southern University of Science and Technology Academy for Advanced Interdisciplinary Studies and Guangdong Provincial Key laboratory of Computational science and Material Design Southern University of Science and Technology Department of Mechanical and Energy Engineering Southern University of Science and Technology Beijing National laboratory for Molecular sciences Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences College of Chemistry and Molecular Engineering National Biomedical Imaging Centre Peking University Guangdong Provincial Key laboratory of Functional Oxide Materials and Devices Southern University of Science and Technology

Enhancing the thermoelectric transport properties of conductive polymer materials has been a long-term challenge, in spite of the success seen with molecular doping strategies. However, the strong coupling between the thermopower and the electrical conductivity limits thermoelectric performance. Here, we use polaron interfacial occupied entropy engineering to break through this intercoupling for a PEDOT:PSS(poly（3,4-ethylenedioxythiophene）-poly（4-styrenesulfonate）) thin film by using photochromic diarylethene（DAE） dopants coupled with UV-light modulation. With a 10-fold enhancement of the thermopower from 13.5 μV K-1to 135.4 μV K-1and almost unchanged electrical conductivity, the DAE-doped PEDOT:PSS thin film achieved an extremely high power factor of 521.28 μW m-1K-2from an original value of 6.78 μW m-1K-2. The thermopower was positively correlated with the UV-light intensity but decreased with increasing temperature, indicating resonant coupling between the planar closed DAE molecule and PEDOT. Both the experiments and theoretical calculations consistently confirmed the formation of an interface state due to this resonant coupling. Interfacial entropy engineering of polarons could play a critical role in enhancing the thermoelectric performance of the organic film.

关键词： thermoelectric PEDOT: PSS interfacial occupied entropy resonant coupling UV-light modulation

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Quantum key distribution over a mimicked dynamic-scattering channel

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science China(Information sciences) 2024年第4期67卷 323-330页

作者： Qi-Hang LU Fang-Xiang WANG Wei CHEN Hai-Yang FU Yin-Jie LU Shuang WANG De-Yong HE Zhen-Qiang YIN Guang-Can GUO Zheng-Fu HAN CAS Key laboratory of Quantum Information University of Science and Technology of China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei National laboratory University of Science and Technology of China

Free-space quantum key distribution(QKD) plays an important role in the global quantum network. However, free space channels suffer from the atmospheric turbulence and scattering effects of haze,fog, and dust, which significantly weaken the performance of QKD or even block the secure quantum link.Here, we prove the performance of QKD over a dynamic scattering channel can be enhanced significantly using a fast wavefront shaping technique. The system achieves on average 10-dB enhancement of quantum transmission efficiency and establishes a secure quantum link for QKD. Our work demonstrates the feasibility of QKD through free-space dynamic scattering channels and enhances the deployment capability of complex-channel QKD system.

关键词： quantum key distribution free space channel channel turbulence channel scattering wavefront shaping

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Minimal Context-Switching Data Race Detection with Dataflow Tracking

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Journal of Computer science & technology 2024年第1期39卷 211-226页

作者：郑龙李洋辛杰刘海峰郑然廖小飞金海 National Engineering Research Center for Big Data technology and System School of Computer Science and Technology Huazhong University of Science and TechnologyWuhan 430074China Services Computing technology and System laboratory School of Computer Science and TechnologyHuazhong University of Science and TechnologyWuhan 430074China Cluster and Grid Computing laboratory School of Computer Science and TechnologyHuazhong University of Science and TechnologyWuhan 430074China

Data race is one of the most important concurrent anomalies in multi-threaded programs.Emerging con-straint-based techniques are leveraged into race detection,which is able to find all the races that can be found by any oth-er sound race detector.However,this constraint-based approach has serious limitations on helping programmers analyze and understand data races.First,it may report a large number of false positives due to the unrecognized dataflow propa-gation of the program.Second,it recommends a wide range of thread context switches to schedule the reported race(in-cluding the false one)whenever this race is exposed during the constraint-solving process.This ad hoc recommendation imposes too many context switches,which complicates the data race analysis.To address these two limitations in the state-of-the-art constraint-based race detection,this paper proposes DFTracker,an improved constraint-based race detec-tor to recommend each data race with minimal thread context switches.Specifically,we reduce the false positives by ana-lyzing and tracking the dataflow in the program.By this means,DFTracker thus reduces the unnecessary analysis of false race schedules.We further propose a novel algorithm to recommend an effective race schedule with minimal thread con-text switches for each data race.Our experimental results on the real applications demonstrate that 1)without removing any true data race,DFTracker effectively prunes false positives by 68%in comparison with the state-of-the-art constraint-based race detector;2)DFTracker recommends as low as 2.6-8.3(4.7 on average)thread context switches per data race in the real world,which is 81.6%fewer context switches per data race than the state-of-the-art constraint based race detec-tor.Therefore,DFTracker can be used as an effective tool to understand the data race for programmers.

关键词： data race satisfiability modulo theory multi-threaded program dynamic detection

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Journal of Computer science & technology 2024年第1期39卷 63-81页

作者：陈章玉华宇左鹏飞孙园园郭云程 Wuhan National laboratory for Optoelectronics School of Computer Science and TechnologyHuazhong University of Science and TechnologyWuhan 430074China

Image bitmaps,i.e.,data containing pixels and visual perception,have been widely used in emerging applica-tions for pixel operations while consuming lots of memory space and energy.Compared with legacy DRAM(dynamic ran-dom access memory),non-volatile memories(NVMs)are suitable for bitmap storage due to the salient features of high density and intrinsic durability.However,writing NVMs suffers from higher energy consumption and latency compared with read accesses.Existing precise or approximate compression schemes in NVM controllers show limited performance for bitmaps due to the irregular data patterns and variance in bitmaps.We observe the pixel-level similarity when writing bitmaps due to the analogous contents in adjacent pixels.By exploiting the pixel-level similarity,we propose SimCom,an approximate similarity-aware compression scheme in the NVM module controller,to efficiently compress data for each write access on-the-fly.The idea behind SimCom is to compress continuous similar words into the pairs of base words with runs.The storage costs for small runs are further mitigated by reusing the least significant bits of base *** adaptively selects an appropriate compression mode for various bitmap formats,thus achieving an efficient trade-off be-tween quality and memory performance.We implement SimCom on GEM5/zsim with NVMain and evaluate the perfor-mance with real-world image/video workloads.Our results demonstrate the efficacy and efficiency of our SimCom with an efficient quality-performance trade-off.

关键词： approximate computing data compression memory architecture non-volatile memory

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The biochemical behavior and mechanism of uranium(Ⅵ)bioreduction induced by natural Bacillus thuringiensis

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Journal of Environmental sciences 2024年第2期136卷 372-381页

作者： Shunzhang Chen Junyuan Gong Yanxia Cheng Yuqi Guo Feize Li Tu Lan Yuanyou Yang Jijun Yang Ning Liu Jiali Liao Key laboratory of Radiation Physics and technology of the Ministry of Education Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China

For a broader understanding of uranium migration affected by microorganisms in natural anaerobic environment,the bioreduction of uranium(Ⅵ)(U(Ⅵ))was revealed in Bacillus thuringiensis,a dominant bacterium strain with potential of uranium-tolerant isolated from uranium contaminated soil.The reduction behavior was systematically investigated by the quantitative analysis of U(Ⅳ)in bacteria,and mechanism was inferred from the pathway of electron transmission.Under anaerobic conditions,appropriate biomass and sodium lactate as electron donor,reduction behavior of U(Ⅵ)induced by B.thuringiensis was restricted by the activity of lactate dehydrogenase,which was directly affected by the initial pH,temperature and initial U(Ⅵ)concentration of bioreduction system.Bioreduction of U(Ⅵ)was driven by the generation of nicotinamide adenine dinucleotide(NADH)from enzymatic reaction of sodium lactate with various dehydrogenase.The transmission of the electrons from bacteria to U(Ⅵ)was mainly supported by the intracellular NADH dehydrogenase-ubiquinone system,this process could maintain the biological activity of cells.

关键词： Uranium Bacillus thuringiensis Bioreduction Electron transmission

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Atomistic study on the microscopic mechanism of grain boundary embrittlement induced by small dense helium bubbles in iron

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Nuclear science and Techniques 2024年第3期35卷 84-95页

作者： Lei Peng Yong-Jie Sun Jing-Yi Shi Yi-Fei Liu Shang-Ming Chen Liu-Liu Li State Key laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Nuclear science and technology University of Science and Technology of ChinaHefei 230027China science and technology on Reactor System Design technology laboratory Nuclear Power Institute of ChinaChengdu 610213China

The helium bubbles induced by 14 MeV neutron irradiation can cause intergranular fractures in reduced activation ferritic martensitic steel,which is a candidate structural material for fusion reactors.In order to elucidate the susceptibility of different grain boundaries(GBs)to helium-induced embrittlement,the tensile fracture processes of 10 types of GBs with and without helium bubbles in body-centered cubic(bcc)iron at the relevant service temperature of 600 K were investigated via molecular dynamics methods.The results indicate that in the absence of helium bubbles,the GBs studied here can be classified into two distinct categories:brittle GBs and ductile GBs.The atomic scale analysis shows that the plastic deformation of ductile GB at high temperatures originates from complex plastic deformation mechanisms,including the Bain/Burgers path phase transition and deformation twinning,in which the Bain path phase transition is the most dominant plastic deformation mechanism.However,the presence of helium bubbles severely inhibits the plastic deformation channels of the GBs,resulting in a significant decrease in elongation at fractures.For bubble-decorated GBs,the ultimate tensile strength increases with the increase in the misorientation angle.Interestingly,the coherent twin boundary∑3{112}was found to maintain relatively high fracture strength and maximum failure strain under the influence of helium bubbles.

关键词： Helium bubble Grain boundary Embrittlement Reduced activation ferritic martensitic steel Molecular dynamics Bain path

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