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Comparison of Rotating Stall Warning by Different Methods for Variable Speed Configurations in a Contra-Rotating Compressor

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Journal of Thermal Science 2024年第4期33卷 1379-1393页

作者： xue Fei WANG Yan'gang LIU Qian wu Tong LIU Hanru School of Power and Energy Northwestern Polytechnical UniversityXi’an710072China

Stall in compressors can cause performance degradation and even lead to *** unacceptable consequences can be avoided by timely monitoring stall inception and taking effective *** paper focused on the rotating stall warning in a low-speed axial contra-rotating ***,the stall disturbance characteristics under different speed configurations were *** results showed that as the speed ratio(RR)increased,the stall disturbance propagation speed based on the rear rotor speed gradually ***,the standard deviation(SD)method,the cross-correlation(CC)method,and the discrete wavelet transform(DWT)method were employed to obtain the stall initiation moments of three different speed *** was found that the SD and CC methods did not achieve significant stall warning results in all three speed ***,the stall initiation moment obtained by the DWT method at RR=1.125 was one period after the stall had fully developed,which was ***,a stall warning method was developed in the present work based on the long short-term memory(LSTM)regression *** applying the LSTM model,the predicted stall initiation moments of three speed configurations were at the 557th,518th,and 333rd revolution,which were44,2,and 74 revolutions ahead of stall onset moments,***,in scenarios where a minor disturbance preceded the stall,the stall warning effect of the LSTM was greatly improved in comparison with the aforementioned three *** contrast,when the pressure fluctuation before the stall was relatively small,the differences between the stall initiation moments predicted by these four methods were not significant.

关键词： contra-rotating compressor stall disturbance stall initiation moment long short-term memory(LSTM) stall warning

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Cross-Project Software Defect Prediction Based on SMOTE and Deep Canonical Correlation Analysis

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Computers, Materials & Continua 2024年第2期78卷 1687-1711页

作者： Xin Fan Shuqing Zhang Kaisheng wu Wei Zheng Yu ge School of Software Nanchang Hangkong UniversityNanchang330063China Software Testing and Evaluation Center Nanchang Hangkong UniversityNanchang330063China

Cross-Project Defect Prediction(CPDP)is a method that utilizes historical data from other source projects to train predictive models for defect prediction in the target ***,existing CPDP methods only consider linear correlations between features(indicators)of the source and target *** models are not capable of evaluating non-linear correlations between features when they exist,for example,when there are differences in data distributions between the source and target *** a result,the performance of such CPDP models is *** this paper,this paper proposes a novel CPDP method based on Synthetic Minority Oversampling Technique(SMOTE)and Deep Canonical Correlation Analysis(DCCA),referred to as *** Correlation Analysis(CCA)is employed to address the issue of non-linear correlations between features of the source and target projects.S-DCCA extends CCA by incorporating the MlpNet model for feature extraction from the *** redundant features are then eliminated by maximizing the correlated feature subset using the CCA loss ***,cross-project defect prediction is achieved through the application of the SMOTE data sampling *** Under Curve(AUC)and F1 scores(F1)are used as evaluation *** paper conducted experiments on 27 projects from four public datasets to validate the proposed *** results demonstrate that,on average,our method outperforms all baseline approaches by at least 1.2%in AUC and 5.5%in F1 *** indicates that the proposed method exhibits favorable performance characteristics.

关键词： Cross-project defect prediction deep canonical correlation analysis feature similarity

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Asymmetrical Fault Current Calculation Method and Influencing Factors Analysis of Droop-Controlled Inverters

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 562-573页

作者： Huimin Zhao Zhikang Shuai Jun ge An Luo Weimin wu Z.John Shen College of Electrical and Information Engineering Hunan UniversityChangsha 410006China Electrical Engineering Department Shanghai Maritime UniversityShanghai 201306China Department of Electrical and Computer Engineering Ilinois Institute of TechnologyChicagoIL 60616 USA

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyzing the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyzed. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyzed. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

关键词： Asymmetrical fault analysis droop control fault current calculation method limiter transient fault characteristics

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A CSP-based retraining framework for motor imagery based brain-computer interfaces

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Science China(Information Sciences) 2024年第8期67卷 349-350页

作者： xue JIANG Lubin MENG Xinru CHEN Dongrui wu Key Laboratory of Image Processing and Intelligent Control School of Artificial Intelligence and AutomationHuazhong University of Science and Technology Shenzhen Huazhong University of Science and Technology Research Institute

Motor imagery(MI) is a classic paradigm of electroencephalogram(EEG)-based brain-computer interfaces(BCIs). It entails individuals mentally imagining the movement of a body part without physically performing it. EEG s... 详细信息

关键词： Classification (of information)

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Quantitative understanding of phase segregation behaviors by precisely building discrete oligo-ester-b-oligo-olefin block copolymers

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Science China Chemistry 2024年第3期67卷 1008-1016页

作者： Yuxin Liu Rui Tan Haibing wu xue-Hui Dong Zhengbiao Zhang College of Chemistry Chemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China State Key Laboratory of Radiation Medicine and Protection Soochow UniversitySuzhou 215123China South China Advanced Institute for Soft Matter Science and Technology School of Molecular Science and EngineeringSouth China University of TechnologyGuangzhou 510640China

Block copolymers(BCPs) with high Flory-Huggins parameter(χ) and balanced surface energy have aroused tremendous interest for ultra-small nanopatterns ***,high χ and balanced surface energy are generally *** fine tune of chain structure might be a useful way to achieve high χ and balanced surface *** realize this,the block copolymer with exactly uniform chain structure,i.e.,defined molecular structure,is highly desirable for accurately evaluating the phase ***,two kinds of discrete oligo ester-b-oligo olefin block copolymers with different chemical structures(oligo lactic acid-boligo olefin BCP,oLA_(n)-b-C_(m);oligo phenyl lactic acid-b-oligo olefin BCP,oPL_(n)-b-C_(m)) were modularly synthesized through iterative growth *** effect of chain structure on segregation strength and surface properties was quantitatively investigated using the discrete BCPs as precise *** the one hand,introducing rigid and nonpolar phenyl groups into oligo ester block has a negligible effect on the chemical incompatibility,as confirmed by the identical high χ values of oLA_(n)-b-C_(m) and oPL_(n)-b-C_(m)(χ_(oLA/C)=0.21 and χ_(oPL/C)=0.19).On the other hand,the incorporation of nonpolar phenyl groups creates balanced surface energy,that is,the high χ and balanced surface energy were simultaneously achieved by oPL_(n)-b-C_(m).Therefore,sub-10 nm perpendicular nanopatterns can be easily produced upon brief thermal treatment,demonstrating its potential application in semiconductor manufacturing with ultra-small feature *** discrete BCP can serve as a quantitative and exquisite model to study the critical contribution of chain structures on phase separation behavior,providing insightful understanding to facilitate the potential application in the chip process.

关键词： discrete polymer iterative growth self-assembly highχ balanced surface

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Projected changes in Köppen-Trewartha climate zones under 1.5-4℃global warming targets over mid-high latitudes of Northern Asia using an ensemble of RegCM4 simulations

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Advances in Climate Change Research 2024年第2期15卷 185-196页

作者： Jie wu xue-Jie GAO Xian-Bing TANG Filippo GIORGI School of geography and Environmental Engineering Gannan Normal UniversityGanzhou 341000China Climate Change Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China The Abdus Salam International Centre for Theoretical Physics Trieste 34100Italy

Mid-high latitude Northern Asia is one of the most vulnerable and sensitive areas to global warming,but relatively less studied *** used an ensemble of a regional climate model(RegCM4)projections to assess future changes in surface air temperature,precipitation and Köppen-Trewartha(K-T)climate types in Northern Asia under the 1.5-4℃global warming ***4 is driven by five CMIP5 global models over an East Asia domain at a grid spacing of 25 *** of the present day(1986-2005)simulations shows that the ensembles of RegCM4(ensR)and driving GCMs(ensG)reproduce the major characters of the observed temperature,precipitation and K-T climate zones reasonably *** and more realistic spatial detail is found in RegCM4 compared to the driving GCMs.A general warming and overall increases in precipitation are projected over the region,with these changes being more pronounced at higher warming *** projected warming by ensR shows different spatial patterns,and is in general lower,compared to ensG in most months of the year,while the percentage increases of precipitation are maximum during the cold *** future changes in K-T climate zones are characterized by a substantial expansion of Dc(temperature oceanic)and retreat of Ec(sub-arctic continental)over the region,reaching∼20%under the 4℃warming *** most notable change in climate types in ensR is found over Japan(∼60%),followed by Southern Siberia,Mongolia,and the Korean Peninsula(∼40%).The largest change in the K-T climate types is found when increasing from 2 to 3℃.The results will help to better assess the impacts of climate change and in implementation of appropriate adaptation measures over the region.

关键词： Mid-high latitudes of Northern Asia Köppen climate zones Global warming targets Regional climate model

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High-throughput calculation-based rational design of Fe-doped MoS_(2) nanosheets for electrocatalytic p H-universal overall water splitting

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Journal of Energy Chemistry 2024年第4期91卷 194-202页

作者： Guangtong Hai Xiangdong xue Zhenyu wu Canyang Zhang Xin Liu Xiubing Huang Institute of Zhejiang University-Quzhou Zhejiang UniversityQuzhou 324000ZhejiangChina Beijing Key Laboratory of Membrane Materials and Engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084China Beijing Advanced Innovation Center for Materials genome Engineering Beijing Key Laboratory of Function Materials for Molecule&Structure ConstructionSchool of Materials Science and EngineeringUniversity of Science and TechnologyBeijing 100083China CentreÉnergie Matériaux et Télécommunications(EMT) Institut national de la recherche scientifique(INRS)Varennes J3X1P7QuébecCanada

Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheets(SFe-DMNs)were prepared based on the high-throughput density functional theory(DFT)calculation *** to the synergistic effect between Fe atom and MoS_(2)and optimized intermediate binding energy,the SFe-DMNs could deliver outstanding activity for both HER and *** assembled into a two-electrode electrolytic cell,the SFe-DMNs could achieve the current density of 50 mA cm^(-2)at a low cell voltage of 1.55 V under neutral *** results not only confirmed the effectiveness of high-throughput screening,but also revealed the excellent activity and thus the potential applications in fuel cells of SFe-DMNs.

关键词： High-throughput calculation Overall water splitting Single atom doped catalyst Molybdenum disulfide nanosheet

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In-situ construction of PDOL electrolyte with dual-reinforced stable interface for high-voltage lithium metal batteries

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Science China Chemistry 2024年第5期67卷 1664-1671页

作者： Yingkang wu Yuzhou Bai wujie Dong xue Wang Wenqin Ma Fuqiang Huang State Key Lab of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China School of Physical Science and Technology Shanghai Tech UniversityShanghai 201210China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050China

In-situ polymerized electrolytes significantly enhance the interfacial compatibility of lithium metal batteries(LMBs). Typically,in-situ polymerized 1,3-dioxolane(PDOL) exhibits low interfacial resistance, yet still suffers from low ionic conductivity and a narrow electrochemical stability window(ESW). Here, an ultra-stable PDOL-based polymer electrolyte is developed by incorporating plasticizers of tetramethylene sulfone(TMS) and fluorinated ethylene carbonate(FEC) into the 3D cross-linked network, achieving a significant enhancement in the transport capacity and efficiency of Li-ion. The ionic conductivity reaches3.63×10^(-4)S cm^(-1)even at room temperature, and the transference number(tLi^(+)) is even higher at 0.85. Furthermore, the ESW of this electrolyte can be increased to 4.5 V with the addition of TMS, which forms a thin and robust antioxidant cathode-electrolyte interface(CEI) on the surface of high-voltage LiCoO_(2). FEC generates an inorganic-rich solid-electrolyte interface(SEI) on the Li anode, which effectively inhibits the growth of lithium dendrites. Benefiting from the aforementioned advantages, the highvoltage lithium metal battery demonstrates outstanding long-cycle stability, with 93.2% capacity retention after 200 cycles. This work offers a straightforward and accessible method for the practical implementation of high energy density in-situ polymerized solid-state LMBs.

关键词： solid polymer electrolyte in-situ polymerization PDOL high-voltage LMBs

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Preoperative prediction of lymphovascular and perineural invasion in gastric cancer using spectral computed tomography imaging and machine learning

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World Journal of Gastroenterology 2024年第6期30卷 542-555页

作者： Hui-Ting ge Jian-wu Chen Li-Li Wang Tian-Xiu Zou Bin Zheng Yuan-Fen Liu Yun-Jing xue Wei-Wen Lin Department of Radiology Fujian Medical University Union HospitalFuzhou 350001Fujian ProvinceChina Fujian Key Laboratory of Intelligent Imaging and Precision Radiotherapy for Tumors Fujian Medical UniversityFuzhou 350001Fujian ProvinceChina Digestive Hematological and Breast MalignanciesClinical Research Center for Radiology and Radiotherapy of Fujian ProvinceFuzhou 350001Fujian ProvinceChina Department of Radiation Oncology Fujian Medical University Union HospitalFuzhou 350001Fujian ProvinceChina Department of Diagnostic Radiology Fujian Medical University Union HospitalFuzhou 350001Fujian ProvinceChina School of Electrical and Computer Engineering University of OklahomaOklahomaOK 73019United States

BACKGROUND Lymphovascular invasion(LVI)and perineural invasion(PNI)are important prognostic factors for gastric cancer(GC)that indicate an increased risk of metastasis and poor *** preoperative prediction of LVI/PNI status could help clinicians identify high-risk patients and guide treatment ***,prior models using conventional computed tomography(CT)images to predict LVI or PNI separately have had limited *** CT provides quantitative enhancement parameters that may better capture tumor *** hypothesized that a predictive model combining clinical and spectral CT parameters would accurately preoperatively predict LVI/PNI status in GC *** To develop and test a machine learning model that fuses spectral CT parameters and clinical indicators to predict LVI/PNI status *** This study used a retrospective dataset involving 257 GC patients(training cohort,n=172;validation cohort,n=85).First,several clinical indicators,including serum tumor markers,CT-TN stages and CT-detected extramural vein invasion(CT-EMVI),were extracted,as were quantitative spectral CT parameters from the delineated tumor ***,a two-step feature selection approach using correlation-based methods and information gain ranking inside a 10-fold cross-validation loop was utilized to select informative clinical and spectral CT parameters.A logistic regression(LR)-based nomogram model was subsequently constructed to predict LVI/PNI status,and its performance was evaluated using the area under the receiver operating characteristic curve(AUC).RESULTS In both the training and validation cohorts,CT T3-4 stage,CT-N positive status,and CT-EMVI positive status are more prevalent in the LVI/PNI-positive group and these differences are statistically significant(Pge,CT-EMVI,single-energy CT values of 70 keV of venous phase(VP-70 keV),and the ratio of standardized iodine co

关键词： Spectral computed tomography Gastric cancer Lymphovascular invasion Perineural invasion

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Experimental Study of Fuel-Air Mixing and Dilution Jets on Outlet Temperature Distribution in a Small Gas Turbine Combustor

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Journal of Thermal Science 2024年第5期33卷 1883-1896页

作者： CAI Wenzhe wu Jing HU Yingqi YANG Zhiqiang xue Xin LIN Yuzhen National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics Research Institute of Aero-EngineBeihang UniversityBeijing 100191China Beijing Institute of Power Machinery Beijing 100074China School of Energy and Power Engineering Beihang UniversityBeijing 100191China

Experimental analysis was conducted to study the impact of fuel-air mixing and dilution jet on the temperature distribution in a small gas turbine combustor using various optical diagnostic *** strength and velocity of the swirler at the venturi exit were adjusted to modify the fuel-air mixture,which is presumed to dominate the heat release of the main combustion ***,the dilution hole configuration,including the number and size of the holes,was varied to investigate the dilution effect on outlet temperature *** optical diagnostic techniques,such as particle image velocimetry,planar Mie scattering,and OH~*chemiluminescence,were used to measure the flow field,fuel spray distribution,and flame structure,respectively.A reduction in swirling strength led to a decrease in the average flow rate in the throat,which improved the structure and symmetry of the axial vortex system in the sleeve,enhanced the mixing of fuel and gas in the dome swirling air,and ultimately,improved the temperature uniformity of the heat release *** to larger and sparse dilution jets,smaller and dense dilution jets tended to generate hot spots shifted towards the radial middle area.

关键词： small gas turbine combustor fuel-air mixing outlet temperature distribution dilution jet laser diagnostics

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