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Journal of Hydrodynamics 2019年第2期31卷 413-420页

作者： Ying-hua Xu Wei-ping Yan kai-rong qin Tun Cao School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyDalian 116024China

This paper presents a three-dimensional flow field simulation of the steady flows through diffusers and nozzles with straight or serrated-sided walls to analyze the effect of the channel structure on the flow characteristics.The pressure and velocity profiles in the diffusers and the nozzles as well as the net volumetric flow rate are determined.Our simulation demonstrates that the pressure and velocity profiles in the serrated diffuser/nozzles are more complicated than those with the straight-sided wall,while the net steady flow rate with the straight-sided wall increases monotonically with the increase of the pressure difference,the steady flow rate with serrated sided walls increases gradually to reach a maximum and then decreases with the increase of the pressure difference.The results suggest that the number of the sawteeth plays a significant role in optimizing the design of serrated diffusers and nozzles for improving the transport efficiency of valveless micro-pumps.

关键词： Valveless micro-pump steady flow diffuser and nozzle serrated-sided wall three-dimensional flow field simulation

Reconfigurable,graphene-coated,chalcogenide nanowires with a sub-10-nm enantioselective sorting capability

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Microsystems & Nanoengineering 2018年第1期4卷 337-344页

作者： Tun Cao Long Tian Huawei Liang kai-rong qin Department of Biomedical Engineering Dalian University of TechnologyDalianChina Shenzhen Key Laboratory of Laser Engineering College of Optoelectronic EngineeringShenzhen UniversityShenzhenChina

Chiral surface plasmon polaritons(SPPs)produced by plasmonic nanowires can be used to enhance molecular spectroscopy for biosensing applications.Nevertheless,the switchable stereoselectivity and detection of various analytes are limited by a lack of switchable,chiral SPPs.Using both finite-element method simulations and analytic calculations,we present a graphene-coated chalcogenide(GCC)nanowire that produces mid-infrared,chiral SPPs.The chiral SPPs can be reversibly switched between“on”(transparent)and“off”(opaque)by non-volatile structural state transitions in the dielectric constants of the chalcogenide glass Ge2Sb2Te5.Furthermore,by controlling the Fermi energy of the graphene-coating layer,the nanowire can output either non-chiral or chiral SPPs.A thermal-electric model was built to illustrate the possibility of ultrafast on/off switching of the SPPs at the terminus of the nanowire.Finally,we show that a selective,lateral sorting of sub-10-nm enantiomers can be achieved via the GCC nanowire.Chiral nanoparticles with opposite handedness experience transverse forces that differ in both their sign and magnitude.Our design may pave the way for plasmonic nanowire networks and tunable nanophotonic devices,which require the ultrafast switching of SPPs,and provide a possible approach for a compact,enantiopure synthesis.

关键词： synthesis chiral Chiral

Empirical likelihood for spatial cross-sectional data models with matrix exponential spatial specification

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 125-139页

作者： LIU Yan rong Jian-rong qin Yong-song Nanning University Nanning 530200China Center for Applied Mathematics of Guangxi and College of Mathematics and Statistics Guangxi Normal UniversityGuilin 541004China

In this paper,we study spatial cross-sectional data models in the form of matrix exponential spatial specification(MESS),where MESS appears in both dependent and error terms.The empirical likelihood(EL)ratio statistics are established for the parameters of the MESS model.It is shown that the limiting distributions of EL ratio statistics follow chi-square distributions,which are used to construct the confidence regions of model parameters.Simulation experiments are conducted to compare the performances of confidence regions based on EL method and normal approximation method.

关键词： MESS empirical likelihood con dence region

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Random Forest-Based Fatigue Reliability-Based Design Optimization for Aeroengine Structures

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 665-684页

作者： Xue-qin Li Lu-kai Song School of Energy and Power Engineering Beihang UniversityBeijing100191China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityKowloonHong Kong999077China Research Institute of Aero-Engine Beihang UniversityBeijing100191China

Fatigue reliability-based design optimization of aeroengine structures involves multiple repeated calculations of reliability degree and large-scale calls of implicit high-nonlinearity limit state function,leading to the traditional direct Monte Claro and surrogate methods prone to unacceptable computing efficiency and accuracy.In this case,by fusing the random subspace strategy and weight allocation technology into bagging ensemble theory,a random forest(RF)model is presented to enhance the computing efficiency of reliability degree;moreover,by embedding the RF model into multilevel optimization model,an efficient RF-assisted fatigue reliability-based design optimization framework is developed.Regarding the low-cycle fatigue reliability-based design optimization of aeroengine turbine disc as a case,the effectiveness of the presented framework is validated.The reliabilitybased design optimization results exhibit that the proposed framework holds high computing accuracy and computing efficiency.The current efforts shed a light on the theory/method development of reliability-based design optimization of complex engineering structures.

关键词： Random forest reliability-based design optimization ensemble learning machine learning

Learning in games:a systematic review

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Science China(Information Sciences) 2024年第7期67卷 133-159页

作者： rong-Jun qin Yang YU National Key Laboratory for Novel Software Technology Nanjing University Polixir Technologies

Game theory studies the mathematical models for self-interested individuals. Nash equilibrium is arguably the most central solution in game theory. While finding the Nash equilibrium in general is known as polynomial parity arguments on directed graphs(PPAD)-complete, learning in games provides an alternative to approximate Nash equilibrium, which iteratively updates the player's strategy through interactions with other players. Rules and models have been developed for learning in games, such as fictitious play and no-regret learning. Particularly, with recent advances in online learning and deep reinforcement learning,techniques from these fields greatly boost the breakthroughs in learning in games from theory to application.As a result, we have witnessed many superhuman game AI systems. The techniques used in these systems evolve from conventional search and learning to purely reinforcement learning(RL)-style learning methods,gradually getting rid of the domain knowledge. In this article, we systematically review the above techniques,discuss the trend of basic learning rules towards a unified framework, and recap applications in large games.Finally, we discuss some future directions and make the prospect of future game AI systems. We hope this article will give some insights into designing novel approaches.

关键词： non-cooperative games learning in games no-regret learning reinforcement learning superhuman AI

Engineered spidroin-derived high-performance fibers for diverse applications

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Nano Research 2024年第2期17卷 492-502页

作者： Dawen qin Jingjing Li Huanrong Li Hongjie Zhang kai Liu National-Local Joint Engineering Laboratory for Energy Conservation in Chemical Process Integration and Resources Utilization Tianjin Key Laboratory of Chemical Process SafetySchool of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Engineering Research Center of Advanced Rare Earth Materials Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing 100084China University of Science and Technology of China Hefei 230026China

Spider silks are well known for their exceptional mechanical properties that are tougher than Kevlar and steel.However,the restricted production amounts from their native sources limit applications of spider silks.Over the decades,there have been significant interests in fabricating man-made silk fibers with comparable performance to natural silks,inspiring many efforts both for biosynthesizing recombinant spider silk proteins(spidroins)in amenable heterologous hosts and biomimetic spinning of artificial spider silks.These strategies provide promising routes to produce high-performance and functionally optimized fibers with diverse applications.Herein,we summarize the hosts that have been applied to produce recombinant spidroins.In addition,the fabrication and mechanical properties of recombinant spidroin fibers and their composite fibers are also introduced.Furthermore,we demonstrate the applications of recombinant spidroin-based fibers.Finally,facing the challenges in biosynthesis,scalable production,and hierarchical assembly of high-performance recombinant spidroins,we give a summary and perspective on future development.

关键词： spider silk recombinant spidroin heterologous expression fiber fabrication mechanical property

Performance Enhancement of Parabolic Trough Collector by Using Homogenizer and Spiral

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Journal of Thermal Science 2024年第2期33卷 658-674页

作者： LI Peijing LIU Taixiu qin Yuanlong ZHENG Zhimei ZHAO kai LIU Qibin School of Energy Powerand Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Science Beijing100049China Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei230027China Research Institute of Science and Technology of China Three Gorges Group Corporation Beijing100038China

In conventional parabolic trough collectors(PTCs),sunlight is concentrated at the bottom of the absorber tube,resulting in a significant circumferential temperature gradient across the absorber tube,heat loss and thermal deformation,which affects the safety and thermal performance of PTCs.In this study,a new receiver with homogenizer and spiral(RHS) is proposed,achieving the optical and thermal synergy to ameliorate the thermal deformation of the absorber tube and enhance thermal efficiency.A plane structure homogenizer is designed to improve uniformity of the concentrated solar flux of absorber tube through second reflection.In combination with the spiral,it improves the optical-thermal efficiency of the PTC by enhancing heat exchange between the fluid and the backlight side of the absorber tube.The performance of the collector is numerically studied by building a three-dimensional coupled light-thermal-structure model.The results show that the thermal deformation of the RHS is reduced by more than 96% and the optical-thermal efficiency is improved by 1.2%-0.63% compared with conventional receivers(CRs) under the same inlet temperature conditions.The proposed receiver is validated to be effective in reducing thermal deformation and improving optical-thermal efficiency.

关键词： parabolic trough collector homogenizer thermal deformation spiral

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Resolution Enhancement of SOHO/MDI Magnetograms

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Research in Astronomy and Astrophysics 2024年第6期24卷 360-369页

作者： Ying qin kai-Fan Ji Hui Liu Xiao-Guang Yu Yunnan Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences Yunnan Key Laboratory of Solar Physics and Space Science Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

Research on the solar magnetic field and its effects on solar dynamo mechanisms and space weather events has benefited from the continual improvements in instrument resolution and measurement frequency. The augmentation and assimilation of historical observational data timelines also play a significant role in understanding the patterns of solar magnetic field variation. Within the realm of astronomical data processing,super-resolution(SR) reconstruction refers to the process of using a substantial corpus of training data to learn the nonlinear mapping between low-resolution(LR) and high-resolution(HR) images, thereby achieving higherresolution astronomical images. This paper is an application study in high-dimensional nonlinear regression. Deep learning models were employed to perform SR modeling on SOHO/MDI magnetograms and SDO/HMI magnetograms, thus reliably achieving resolution enhancement of full-disk SOHO/MDI magnetograms and enhancing the image resolution to obtain more detailed information. For this study, a data set comprising 9717pairs of data from 2010 April to 2011 February was used as the training set, 1332 pairs from 2011 March were used as the validation set and 1034 pairs from 2011 April were used as the test set. After data preprocessing, we randomly cropped 128 × 128 sub-images as the LR cases from the full-disk MDI magnetograms, and the corresponding 512 × 512 sub-images as HR ones from the HMI full-disk magnetograms for model training. The tests conducted have shown that the study successfully produced reliable 4× SR reconstruction of full-disk MDI magnetograms. The MESR model's results(0.911) were highly correlated with the target HMI magnetographs as indicated by the correlation coefficient values. Furthermore, the method achieved the best PSNR, SSIM, MAE and RMSE values, indicating that the MESR model can effectively reconstruct magnetograms.

关键词： magnetic fields Sun: magnetic fields techniques: image processing virtual observatory tools

Learning accurate template matching with differentiable coarseto-fine correspondence refinement

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Computational Visual Media 2024年第2期10卷 309-330页

作者： Zhirui Gao Renjiao Yi Zheng qin Yunfan Ye Chenyang Zhu kai Xu College of Computer National University of Defense TechnologyChangsha 410073China

Template matching is a fundamental task in computer vision and has been studied for decades.It plays an essential role in manufacturing industry for estimating the poses of different parts,facilitating downstream tasks such as robotic grasping.Existing methods fail when the template and source images have different modalities,cluttered backgrounds,or weak textures.They also rarely consider geometric transformations via homographies,which commonly exist even for planar industrial parts.To tackle the challenges,we propose an accurate template matching method based on differentiable coarse-tofine correspondence refinement.We use an edge-aware module to overcome the domain gap between the mask template and the grayscale image,allowing robust matching.An initial warp is estimated using coarse correspondences based on novel structure-aware information provided by transformers.This initial alignment is passed to a refinement network using references and aligned images to obtain sub-pixel level correspondences which are used to give the final geometric transformation.Extensive evaluation shows that our method to be significantly better than state-of-the-art methods and baselines,providing good generalization ability and visually plausible results even on unseen real data.

关键词： template matching differentiable homography structure-awareness transformers

Study on the interannual variability of the Kerama Gap transport and its relation to the Kuroshio/Ryukyu Current system

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Acta Oceanologica Sinica 2024年第3期43卷 1-14页

作者： Han Zhou kai Yu Jianhuang qin Xuhua Cheng Meixiang Chen Changming Dong Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210003China College of Oceanography Hohai UniversityNanjing 210003China School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 211800China

An analysis of a 68-year monthly hindcast output from an eddy-resolving ocean general circulation model reveals the relationship between the interannual variability of the Kerama Gap transport(KGT)and the Kuroshio/Ryukyu Current system.The study found a significant difference in the interannual variability of the upstream and downstream transports of the East China Sea-(ECS-)Kuroshio and the Ryukyu Current.The interannual variability of the KGT was found to be of paramount importance in causing the differences between the upstream and downstream ECS-Kuroshio.Additionally,it contributed approximately 37%to the variability of the Ryukyu Current.The interannual variability of the KGT was well described by a two-layer rotating hydraulic theory.It was dominated by its subsurface-intensified flow core,and the upper layer transport made a weaker negative contribution to the total KGT.The subsurface flow core was found to be mainly driven by the subsurface pressure head across the Kerama Gap,and the pressure head was further dominated by the subsurface density anomalies on the Pacific side.These density anomalies could be traced back to the eastern open ocean,and their propagation speed was estimated to be about 7.4 km/d,which is consistent with the speed of the local first-order baroclinic Rossby wave.When the negative(positive)density anomaly signal reached the southern region of the Kerama Gap,it triggered the increase(decrease)of the KGT towards the Pacific side and the formation of an anticyclonic(cyclonic)vortex by baroclinic adjustment.Meanwhile,there is an increase(decrease)in the upstream transport of the entire Kuroshio/Ryukyu Current system and an offshore flow that decreases(increases)the downstream Ryukyu Current.

关键词： Kerama Gap Kuroshio Ryukyu Current OGCM for the Earth Simulator(OFES) hydraulic theory

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