检索结果-南通市图书馆

Journal of Thermal Science 2024年第4期33卷 1421-1442页

作者： QIN Runxuan ZHOU Xun WANG Songtao CAI le School of Energy Science and Engineering Harbin Institute of TechnologyHarbin150001China

A numerical study is conducted to elucidate the impact of hole shapes and additional flow angles on the flow structure of the coolant and temperature field in the leading edge area of the gas turbine *** typical hole shapes are considered for the GE-E3 *** impact of the additional flow angle(E)within each hole shape on the temperature field is *** results indicate that for the leading edge area and suction surface,the fan-shaped hole case performs best in decreasing temperatures,with a decrease of about 43 *** is mainly due to the fact that the fan-shaped hole has the maximum expansion in hole spanwise *** the pressure surface,the console hole case performs best in decreasing temperatures,with a maximum reduction of about 47.2 *** influence of E on the surface temperature at leading edge area varied between the different hole *** the cylinder hole and console hole,the E=-20°case has the lowest area-averaged *** both the fan-shaped hole and the 7-7-7 shaped hole are expansion holes,the pattern of variation of the leading edge area temperature with increasing E is similar for the fan-shaped hole case and 7-7-7 shaped hole *** E=20°case shows the lowest spanwise-averaged temperature near the hole outlet,and the E=-20°case shows the lowest spanwise-averaged temperature further downstream.

关键词： film cooling GE-E3 turbine rotor blade conjugate heat transfer leading edge

维普期刊数据库

Your personal choices in transportation and food are important for lowering carbon emissions

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2024年第6期18卷 27-32页

作者： Bruce Logan Fang Zhang Wulin Yang le Shi Institute of Energy and the Environment The Pennsylvania State UniversityUniversity ParkPA 16802USA School of Environment Tsinghua UniversityBeijing 100084China College of Environmental Sciences and Engineering Peking UniversityBeijing 100871China College of Environmental and Resource Sciences Zhejiang UniversityHangzhou 310058China

There is a global need to reduce greenhouse gas emissions to limit the extent of climate change.A better understanding of how our own activities and lifestyle influence our energy use and carbon emissions can help us enable changes in activities that can lead to reductions in carbon *** we discuss an approach based on examining carbon emissions from the perspective of the unit C,where 1 C is the CO_(2)from food a person would on average eat every *** approach shows that total CO_(2)emissions in China,normalized by the population,is 22.5 C while carbon emissions for a person in the US is 43.9 C.A better appreciation of our own energy use can be obtained by calculating carbon emissions from our own activities in units of C,for example for driving a car gasoline or electric vehicle a certain number of kilometers,using electricity for our homes,and eating different *** this information,we can see how our carbon emissions compare to national averages in different countries and make decisions that could lower our personal CO_(2)emissions.

关键词： Carbon dioxide Climate change Daily energy Greenhouse gas

Re-entry rocket basic flow characteristics and thermal environment of different retro-propulsion modes

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 2024年第7期37卷 190-203页

作者： Yifei SU Peijie SUN Yangwen CUI Guigao le School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China Shanghai Institute of Aerospace System Engineering Shanghai 200000China Southwest Institute of Technology and Engineering Chongqing 400039China

During the supersonic re-entry of multi-nozzle heavy rockets into the atmosphere,the basic flow state becomes increasingly complex due to the coupling effect between the retropropulsion plumes and the freestream.A numerical method using the hybrid Reynolds-Averaged Navier-Stokes and Large Eddy Simulation(RES)method and discrete coordinate method is developed to accurately estimate the thermal *** addition,finite rate chemical kinetics is used to calculate the afterburning *** numerical results agree well with wind tunnel data,which confirms the validity and accuracy of the numerical *** are conducted for the heavy carrier rocket re-entry from 53.1 km to 39.5 km altitude with 180°angle of attack by using three different Supersonic Retro-Propulsion(SRP)*** numerical results reveal that these three SRP flow fields are all Short Penetration Models(SPM).As the re-entry altitudes decrease,both the plume-plume interaction and the plume-freestream interaction become *** highest temperatures in the plume shear layers of the three SRP modes increase by 8.36%,7.33%and 6.92%respectively after considering afterburning reactions,and all occur at a reentry altitude of 39.5 *** the rocket re-enters the atmosphere,the maximum heat flux on the rocket base plate of three SRP modes stabilizes at 290,170 and 200 kW/m^(2) respectively,but the maximum heat flux on the side wall increases *** the altitude declines to 39.5 km,the extreme heat flux of the three modes increase by 84.16%,49.45%and 62.97%respectively compared to that at 53.1 km.

关键词： Re-entry rocket Multi-nozzle Supersonic retro propulsion Thermal environment Afterburning effect

维普期刊数据库

Linearized waveform inversion for vertical transversely isotropic elastic media:Methodology and multi-parameter crosstalk analysis

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第1期21卷 252-271页

作者： Ke Chen Lu Liu Li-Nan Xu Fei Hu Yuan Yang Jia-Hui Zuo le-le Zhang Yang Zhao National Key Laboratory of Petroleum Resources and Engineering Unconventional Petroleum Research InstituteChina University of Petroleum(Beijing)Beijing102249China Aramco Beijing Research Center Aramco AsiaBeijing100102China University of Lausanne LausanneCH-1015Switzerland Bureau of Geophysical Prospecting China National Petroleum CorporationZhuozhou 072750HebeiChina

Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon *** migration aims at obtaining structural images of subsurface geologic *** specifically,seismic migration estimates the reflectivity function(stacked average reflectivity or pre-stack angle-dependent reflectivity)from seismic reflection *** the other hand,seismic inversion quantitatively estimates the intrinsic rock properties of subsurface *** seismic inversion methods are applicable to detect hydrocarbon reservoirs that may exhibit lateral variations in the inverted *** there exist many differences,pre-stack seismic migration is similar with the first iteration of the general linearized seismic ***,seismic migration and inversion techniques assume an acoustic or isotropic elastic *** reservoirs such as shale and tight sand formation have notable anisotropic *** present a linearized waveform inversion(LWI)scheme for weakly anisotropic elastic media with vertical transversely isotropic(VTI)*** is based on two-way anisotropic elastic wave equation and simultaneously inverts for the localized perturbations(ΔVp_(0)/Vp_(0)/Vs_(0)/Vs_(0)/,Δ∈,Δδ)from the long-wavelength reference *** proposed VTI-elastic LWI is an iterative method that requires a forward and an adjoint operator acting on vectors in each *** derive the forward Born approximation operator by perturbation theory and adjoint operator via adjoint-state *** inversion has improved the quality of the images and reduces the multi-parameter crosstalk comparing with the adjoint-based *** have observed that the multi-parameter crosstalk problem is more prominent in the inversion images for Thomsen anisotropy ***,the Thomsen parameter is the most difficult to *** also analyze the multi-parameter crosstalk using scattering radiation patte

关键词： Elastic Anisotropy least-squares imaging Waveform inversion Computational geophysics

维普期刊数据库

Path signature-based XAI-enabled network time series classification

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第7期67卷 91-106页

作者： le SUN Yueyuan WANG Yongjun REN Feng XIA Department of Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET) Nanjing University of Information Science and Technology School of Computing Technologies Royal Melbourne Institute of Technology

Classifying network time series(NTS) is crucial for automating network administration and ensuring cyberspace security. It enables the detection of anomalies, the identification of network attacks,and the monitoring of performance issues, thereby providing valuable support for network protection and optimization. However, modern communication networks pose challenges for NTS classification *** include handling large-scale and complex NTS data, extracting features from intricate datasets, and addressing explainability requirements. These challenges are particularly pronounced for complex 5G networks. Notably, explainability has become crucial for the widespread deployment of network automation for 5G networks and beyond. To tackle these challenges, we propose a path-signature-based NTS classification model called recurrent signature(Recur Sig). This innovative model is designed to overcome the time-consuming feature selection problem by utilizing deep-learning(DL) techniques. Additionally, it provides a solution for addressing the black-box issue associated with DL models in network automation systems(NAS) by incorporating an explainable classification approach. Extensive experimentation on various public datasets demonstrates that Recur Sig outperforms existing models in accuracy and explainability. The results indicate its potential for application in cyberspace security and automated network management, offering an explainable solution for network protection and optimization.

关键词： network time series classification explainable artificial intelligence path signature automated network management recurrent neural network

Energy harvesting technology for AC overhead insulated transmission line based on electric field induction

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2024年第4期9卷 816-825页

作者： le Zhou Hongwei Liu Kun Zuo Kuo Shang School of Electrical and Electronic Engineering North China Electric Power UniversityBeijingChina Electric Power Company of Sichuan Province Tianfu Power Supply Company ChengduSichuanChina Changde Power Supply Branch State Grid Hunan Electric Power Company LimitedChangdeHunanChina

To solve the problem of the energy harvesting(EEH)effect of the condition monitoring devices power supply on the transmission line is not *** authors designed three kinds of EEH schemes based on AC electric field induction,which can effectively improve the output power of load power *** EEH principle of each scheme was analysed in detail,and the influence factors such as the shape of outer energy harvester,capacitance compensation and impedance matching characteristics were ***,the experiment showed that 140.9 mW of power was obtained in direct-mode field EEH when the line voltage level was 10 *** high-potential field EEH mode obtained 4.1 mW of *** harvesting effect of the inner energy harvester with the same potential as the aluminium wire was obviously better,and 30.7 mW of power was ***,based on the third mode,when the load resistance was 2200Ω,the rectifier received 23.7 mW DC *** experimental results are in agreement with the theoretical analysis,which verifies the effectiveness of the electric field induction power supply technology.

关键词： field harvesting mode

Proposing a machine learning approach to analyze and predict basic high-temperature properties of iron ore fines and its factors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第5期31卷 1082-1094页

作者： Qing-ke Sun Yao-zu Wang Jian-liang Zhang Zheng-jian Liu le-le Niu Chang-dong Shan Yun-fei Ma Institute of Artificial Intelligence University of Science and Technology BeijingBeijing100083China School of Intelligence Science and Technology University of Science and Technology BeijingBeijing100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China

The basic high-temperature properties of iron ore play a crucial role in optimizing sintering and ore blending,but the testing process for these properties is complex and has significant lag time,which cannot meet the actual needs of ore blending.A prediction model for the basic high-temperature properties of iron ore fines was thus proposed based on a combination of machine learning algorithms and genetic ***,the prediction accuracy of different machine learning models for the basic high-temperature properties of iron ore fines was ***,a random forest model optimized by genetic algorithms was built,further improving the prediction accuracy of the *** test results show that the random forest model optimized by genetic algorithms has the highest prediction accuracy for the lowest assimilation temperature and liquid phase fluidity of iron ore,with a determination coefficient of 0.903 for the lowest assimilation temperature and 0.927 for the liquid phase fluidity after *** trained model meets the fluctuation requirements of on-site testing and has been successfully applied to actual production on site.

关键词： Iron ore Basic high-temperature property Machine learning Random forest Genetic algorithm

Structural phase transition in a new organic-inorganic hybrid post-perovskite:(N,N-dimethylpyrrolidinium)[Mn(N(CN)_(2))_(3)]

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 Structural Chemistry 2024年第6期43卷 40-44页

作者： le Ye Wei-Xiong Zhang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of ChemistryIGCMESun Yat-Sen UniversityGuangzhou510275China

In the realm of molecular phase transition research,particularly for applications in sensors,data storage and switching technologies,the role of organic-inorganic hybrid perovskite materials has been increasingly recognized for their significant ***,hybrid post-perovskites,as a critical subclass of perovskites,have not been thoroughly studied and mainly limit in the instances based on polyatomic bridging agents like dicyanamide(dca^(-))and non-cyclic organic ***,a polar cyclic quaternary ammonium cation,N,N-dimethylpyrrolidinium(DMP^(+)),was used to assemble a new hybrid post-perovskite,(DMP)[Mn(dca)_(3)](1),which undergoes a phase transition from orthorhombic Bmmb to monoclinic P2_(1)/n space group at 249 *** employing multiple techniques such as differential scanning calorimetry,variable-temperature single-crystal X-ray analysis,dielectric measurements,and Hirshfeld surface analysis,we disclosed the role of polar cyclic quaternary ammonium DMP^(+)in elevating the phase-transition temperature by 48 K,generating significant dielectric switching effect and facilitating interlayer sliding of inorganic framework.

关键词： Structural phase transitions Dielectric switching Organic-inorganic hybrid crystals Post-perovskites

Workout Action Recognition in Video Streams Using an Attention Driven Residual DC-GRU Network

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5期79卷 3067-3087页

作者： Arnab Dey Samit Biswas Dac-Nhuong le Department of Computer Science and Technology Indian Institute of Engineering Science and TechnologyShibpurHowrah711103India Faculty of Information Technology Haiphong UniversityHaiphong180000Vietnam

Regular exercise is a crucial aspect of daily life, as it enables individuals to stay physically active, lowers thelikelihood of developing illnesses, and enhances life expectancy. The recognition of workout actions in videostreams holds significant importance in computer vision research, as it aims to enhance exercise adherence, enableinstant recognition, advance fitness tracking technologies, and optimize fitness routines. However, existing actiondatasets often lack diversity and specificity for workout actions, hindering the development of accurate recognitionmodels. To address this gap, the Workout Action Video dataset (WAVd) has been introduced as a significantcontribution. WAVd comprises a diverse collection of labeled workout action videos, meticulously curated toencompass various exercises performed by numerous individuals in different settings. This research proposes aninnovative framework based on the Attention driven Residual Deep Convolutional-Gated Recurrent Unit (ResDCGRU)network for workout action recognition in video streams. Unlike image-based action recognition, videoscontain spatio-temporal information, making the task more complex and challenging. While substantial progresshas been made in this area, challenges persist in detecting subtle and complex actions, handling occlusions,and managing the computational demands of deep learning approaches. The proposed ResDC-GRU Attentionmodel demonstrated exceptional classification performance with 95.81% accuracy in classifying workout actionvideos and also outperformed various state-of-the-art models. The method also yielded 81.6%, 97.2%, 95.6%, and93.2% accuracy on established benchmark datasets, namely HMDB51, Youtube Actions, UCF50, and UCF101,respectively, showcasing its superiority and robustness in action recognition. The findings suggest practicalimplications in real-world scenarios where precise video action recognition is paramount, addressing the persistingchallenges in the field. TheWAVd datas

关键词： Workout action recognition video stream action recognition residual network GRU attention

Prognostic value of N-terminal pro B-type natriuretic peptide and troponin Ⅰ in children with dengue shock syndrome

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2024年第4期17卷 166-172页

作者： Truyen Phuoc le Phung Nguyen The Nguyen University of Medicine and Pharmacy at Ho Chi Minh city Ho Chi Minh CityVietnam Children's Hospital 1 Ho Chi Minh CityVietnam

Objective:To investigate the contribution of N-terminal pro B-type natriuretic peptide(NT-pro BNP)and troponin Ⅰ to mortality in children with dengue shock ***:A longitudinal study was conducted on children with dengue shock syndrome in a hospital in southern *** clinical histories,physical examinations,and laboratory parameters,including NT-pro BNP and troponin Ⅰ,were recorded.A comparison between survival and non-survival was carried out to identify factors influencing ***:A total of 107 patients with a median age of 9 years were included in the *** them,63.6%(68/107)presented with compensated shock,36.4%(39/107)had hypotensive shock,23.4%(25/107)required mechanical ventilation,and 12.1%(13/107)*** NT-pro BNP levels were 3.9 pmol/L(IQR:1.9,10.3)and 15.2 pmol/L(5.8,46.3),while the median high sensitivity troponin Ⅰ levels were 20 pg/L(6,95)and 62 pg/L(12,325)at the first and second measurements,*** mortality group exhibited higher rates of hypotensive shock,prolonged shock,lactate levels,liver damage,NT-pro BNP,and troponin Ⅰ *** shock(OR 12.96,95%CI 2.70-62.30,P=0.004),prolonged shock(OR 39.40,95%CI 6.68-232.70,P1000 IU/L(OR 9.50,95%CI 2.63-34.34,P=0.041),and NT-pro BNP>7 pmol/L(OR 44.40,95%CI 5.44-362.20,P=0.001)were identified as predictive factors for mortality in dengue shock ***:The NT-pro BNP level could serve as a potential biomarker for predicting mortality in children with dengue shock syndrome.

关键词： Dengue shock syndrome Cardiac enzyme NT-pro BNP TroponinⅠ