检索结果-南通市图书馆

Study on the Relationship between Structural Aspects and Aerodynamic Characteristics of Archimedes Spiral Wind Turbines

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2024年第7期20卷 1517-1537页

作者： Yuanjun Dai Zetao Deng Baohua Li Lei Zhong Jianping Wang Mechanical and Electrical Engineering institue Xinjiang Agricultural UniversityUrumqi830052China College of Mechanics Shanghai DianJi UniversityShanghai201306China School of energy Engineering Xinjiang Institute of EngineeringUrumqi830023China

A combined experimental and numerical research study is conducted to investigate the complex relationship between the structure and the aerodynamic performances of an Archimedes spiral wind turbine(ASWT).Two ASWTs are considered,a prototypical version and an improved *** is shown that the latter achieves the best aerodynamic performance when the spread angles at the three sets of blades areα_(1)=30°,α_(2)=55°,α3=60°,respectively and the blade thickness is 4 *** a velocity V=10 m/s,a tip speed ratio(TSR)=1.58 and 2,the maximum CP values are 0.223 and 0.263 for the prototypical ASWT and improved ASWT,respectively,and the maximum C_(P) enhancement is 17.93%.For V=10 m/s and TSR=2,the CP values of the prototypical ASWT and improved ASWT are 0.225 and 0.263,respectively,with an aerodynamic performance enhancement of 16.88%.Through mutual verification of the test outcomes and numerical results,it is concluded that the proposed approach can effectively lead to aerodynamic performance improvement.

关键词： Archimedes spiral wind turbine aerodynamic performance numerical calculation

Defect Detection Model Using Time Series Data Augmentation and Transformation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第2期78卷 1713-1730页

作者： Gyu-Il Kim Hyun Yoo Han-Jin Cho Kyungyong Chung Department of Computer Science Kyonggi UniversitySuwon-si16227Korea Contents Convergence Software Research institue Kyonggi UniversitySuwon-si16227Korea Department of energy IT Engineering Far East UniversityEumsung-gun27601Korea Division of AI Computer Science and Engineering Kyonggi UniversitySuwon-si16227Korea

Time-series data provide important information in many fields,and their processing and analysis have been the focus of much ***,detecting anomalies is very difficult due to data imbalance,temporal dependence,and ***,methodologies for data augmentation and conversion of time series data into images for analysis have been *** paper proposes a fault detection model that uses time series data augmentation and transformation to address the problems of data imbalance,temporal dependence,and robustness to *** method of data augmentation is set as the addition of *** involves adding Gaussian noise,with the noise level set to 0.002,to maximize the generalization performance of the *** addition,we use the Markov Transition Field(MTF)method to effectively visualize the dynamic transitions of the data while converting the time series data into *** enables the identification of patterns in time series data and assists in capturing the sequential dependencies of the *** anomaly detection,the PatchCore model is applied to show excellent performance,and the detected anomaly areas are represented as heat *** allows for the detection of anomalies,and by applying an anomaly map to the original image,it is possible to capture the areas where anomalies *** performance evaluation shows that both F1-score and Accuracy are high when time series data is converted to ***,when processed as images rather than as time series data,there was a significant reduction in both the size of the data and the training *** proposed method can provide an important springboard for research in the field of anomaly detection using time series ***,it helps solve problems such as analyzing complex patterns in data lightweight.

关键词： Defect detection time series deep learning data augmentation data transformation

A spanwise loss model for axial compressor stator based on machine learning

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第11期35卷 74-84页

作者： Zixuan YUE Chenghua ZHOU Donghai JIN Xingmin GUI Aeroengine Simulation Research Center School of Energy and Power EngineeringBeihang UniversityBeijing 100083China Jiangxi Research institue of Beihang University Nanchang 330096China

In the early stage of aircraft engine design, the through-flow method is an important tool for designers. The accuracy of the through-flow method depends heavily on the accuracy of the loss model. However, most existing models cannot(or cannot well) provide the spanwise loss distribution. To construct an effective spanwise loss model, both turbomachinery knowledge and machine learning skills were used in this paper. A large number of numerical simulations were carried out to build a database containing more than 1000 compressor cascade numerical samples. Secondary flow intensity was introduced as the independent variable to carry out feature engineering. A model containing a selector based on support vector machine regression and estimators based on K-nearest neighbor regression was constructed. Numerical test set and design data of two former highpressure core compressors were used for validation. Results suggest that the spanwise loss model show good consistency with both numerical test set and data of two former compressors. It can reflect the influence of secondary flow and can also predict both value and trend of total pressure loss coefficient well, with mean absolute error general around or less than 1% and R^(2)(coefficient of determination) more than 0.8 on the test set. Especially when dealing with loss coefficient at midspan position, the model shows even better performance, with R^(2)over 0.97 on the test set. And the selector of the model can well classify the samples, predict the intensity of secondary flow and help estimators to capture the phenomenon that end-wall secondary flow extends to the mid-span.

关键词： Compressor Loss model Machine learning Modeling Through-flow method

Two－Phase　Critical　Discharge　of　Initially　Saturated　or　Subcooled　Water　Flowing　in　Sharp－Edged　Tubes　at　High　Pressure

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 1995年第3期4卷 193-199页

作者： Jinliang Xu Tingkuan Chen Luwei Yang institue of Nuclear energy Technology Tsinghua University Beijing China National Lab. on Multiphase Flow Xi’an Jiaotong University China

The transient critical flow experiment with sharp-edged tubes as the break geometries is conducted in high pressure convective circulation test loop of Xi'an Jiaotong University. The initial steady operation pressure is up to ***. An empirical correlation was made to obtain the critical mass flow rates, the critical pressure ratio and the thermal nonequilibrium number were correlated as the functions of the tube length to tube diameter ratio L/D. The predicted critical mass now rate gets a higher accuracy for short tubes with L/D 12.

关键词： critical flow thermal nonequilibrium sharp-edged tubes.

FePO4-coated Li[Li0.2Ni0.13Co0.13Mn0.54]O2 with improved cycling performance as cathode material for Li-ion batteries

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2017年第11期36卷 899-904页

作者： Zhong Wang Hua-Quan Lu Yan-Ping Yin Xue-Yi Sun Xiang-Tao Bai Xue-Ling Shen Wei-Dong Zhuang Shi-Gang Lu R&D Center for Vehicle and energy Storage General Research Institute of Nonferrous Metals Beijing 100088 China China Automotive Battery Research institue Co. Ltd Beijing 100088 China

Li[Li0.2Ni0.13Coo.13Mn0.54]O2 cathode materials were synthesized by carbonate-based co-precipitation method, and then, its surface was coated by thin layers of FePO4. The prepared samples were characterized by X-ray diffraction （XRD）, field emission scanning electron micro- scope （FESEM）, energy-dispersive spectroscopy （EDS）, and transmission electron microscopy （TEM）. The XRD and TEM results suggest that both the pristine and the coated materials have a hexagonal layered structure, and the FePO4 coating layer does not make any major change in the crystal structure. The FePO4-coated sample exhibits both improved initial discharge capacity and columbic efficiency compared to the pristine one. More significantly, the FePO4 coating layer has a much positive influence on the cycling perfor- mance. The FePO4-coated sample exhibits capacity reten- tion of 82 % after 100 cycles at 0.5℃ between 2.0 and 4.8 V, while only 28 % for the pristine one at the same charge-discharge condition. The electrochemical impe- dance spectroscopy （EIS） results indicate that this improved cycling performance could be ascribed to the presence of FePO4 on the surface of Li[Li0.2Ni0.13Co0.13Mno.54102 par- ticle, which helps to protect the cathode from chemical attacks by HF and thus suppresses the large increase in charge transfer resistance.

关键词： Cathodes Charge transfer Coated materials Coatings Crystal structure Electric batteries Electrochemical impedance spectroscopy Electrodes energy dispersive spectroscopy Field emission cathodes High resolution transmission electron microscopy Lithium Lithium alloys Lithium compounds Manganese Nickel Precipitation (chemical) Scanning electron microscopy Secondary batteries Transmission electron microscopy X ray diffraction

Influence of interface states, conduction band offset, and front contact on the performance of a-SiC：H(n)/c-Si(p)heterojunction solar cells

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第6期26卷 534-540页

作者：乔治冀建利张彦立刘虎李同锴 institue of Applied Physics Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang 050043 China

P-type silicon heterojunction（SHJ） solar cells with a-SiC：H（n） emitters were studied by numerical computer simulation in this paper. The influence of interface states, conduction band offset, and front contact on the performance of a-SiC：H（n）/c-Si（p） SHJ solar cells was investigated systematically. It is shown that the open circuit voltage（Voc） and fill factor（F F） are very sensitive to these parameters. In addition, by analyzing equilibrium energy band diagram and electric field distribution, the influence mechanisms that interface states, conduction band offset, and front contact impact on the carrier transport, interface recombination and cell performance were studied in detail. Finally, the optimum parameters for the a-SiC：H（n）/c-Si（p） SHJ solar cells were provided. By employing these optimum parameters, the efficiency of SHJ solar cell based on p-type c-Si was significantly improved.

关键词： silicon heterojunction solar cells interface states band offset front contact

HTL resummation in the light cone gauge

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2018年第4期42卷 91-104页

作者：陈奇侯德富 Key Laboratory of Quark and Lepton Physics (MOE) Institue of Particle Physics Central China Normal University

The light cone gauge with light cone variables is often used in p QCD calculations in relativistic heavyion collision physics. The Hard Thermal Loops(HTL) resummation is an indispensable technique for hot QCD calculation. It was developed in covariant gauges with conventional Minkowski varaiables; we shall extend this method to the light cone gauge. In the real time formalism, using the Mandelstam-Leibbrant prescription of(n·K)-1,we calculate the transverse and longitudinal components of the gluon HTL self energy, and prove that there are no infrared divergences. With this HTL self energy, we derive the HTL resummed gluon propagator in the light cone gauge. We also calculate the quark HTL self energy and the resummed quark propagator in the light cone gauge and find it is gauge independent. As application examples, we analytically calculate the damping rates of hard quarks and gluons with the HTL resummed gluon propagator in the light cone gauge and showed that they are gauge independent. The final physical results are identical to those computed in covariant gauge, as they should be.

关键词： hard thermal loop light cone gauge damping rate

THE ROLE OF PARTON HARD SCATTERING IN HADRONIC INTERACTIONS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1986年第7期3卷 289-292页

作者： ZHU Qingqi DING Linkai JING Cailiu JING Guiru institue of High energy Physics Acadamia SinicaBeijing

A soft-hard two-component approach to the description of high energy hadronic interactions is *** shows the important role of parton hard scattering in explanation of the chief characteristics of high energy hadronic ... 详细信息

关键词： interactions explanation hadron

Evolution of a mining induced fracture network in the overburden strata of an inclined coal seam

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2012年第6期22卷 775-779页

作者： Wei Xiujun Gao Mingzhong Lv Youchang Shi Xiangchao Gao Hailian Zhou Hongwei institue of energy & Chemical Industry China Pingmei Shenma Group School of Hydraulic and Hydropower Engineering Sichuan University State Key Laboratory of Coal Resources and Safe Mining China University of Mining & Technology

The geological conditions of the Pingdingshan coal mining group were used to construct a physical model used to study the distribution and evolution of mining induced cracks in the overburden *** graphics technology and fractal theory are introduced to characterize the distribution and growth of the mining induced fractures in the overburden strata of an inclined coal seam.A relationship between fractal dimension of the fracture network and the pressure in the overburden strata is *** induced fractures spread dynamically to the mining face and up into the roof as the length of advance ***,the fractal dimension of the fracture network increases with increased mining length,in general,but decreases during a period from overburden strata separation until the main roof *** is a1so shown that overburden strata pressure plays an important role in the evolution of mining induced fractures and that the fractal dimension of the fractures increases with the pressure of the overburden.

关键词： Inclined coal seam Fracture network Evolution Fractal dimension