检索结果-南通市图书馆

维普期刊数据库博看期刊

A Deep Model for Partial Multi-label Image Classification with Curriculum-based Disambiguation

在线全文

学校读者我要写书评

暂无评论

Machine Intelligence Research 2024年第4期21卷 801-814页

作者： feng Sun Ming-Kun Xie Sheng-jun huang MIIT Key Laboratory of Pattern Analysis and Machine Intelligence College of Computer Science and TechnologyNanjing University of AeronauticsandAstronauticsNanjing211106China

In this paper,we study the partial multi-label(PML)image classification problem,where each image is annotated with a candidate label set consisting of multiple relevant labels and other noisy *** PML methods typically design a disambiguation strategy to filter out noisy labels by utilizing prior knowledge with extra assumptions,which unfortunately is unavailable in many real ***,because the objective function for disambiguation is usually elaborately designed on the whole training set,it can hardly be optimized in a deep model with stochastic gradient descent(SGD)on *** this paper,for the first time,we propose a deep model for PML to enhance the representation and discrimination *** the one hand,we propose a novel curriculum-based disambiguation strategy to progressively identify ground-truth labels by incorporating the varied difficulties of different *** the other hand,consistency regularization is introduced for model training to balance fitting identified easy labels and exploiting potential relevant *** experimental results on the commonly used benchmark datasets show that the proposed method significantlyoutperforms the SOTA methods.

关键词： Partial multi-label image classification curriculum-based disambiguation consistency regularization label difficulty candidatelabel set.

Long-term continuous energy injection in the afterglow of GRB 060729

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

Research in Astronomy and Astrophysics 2009年第12期9卷 1317-1323页

作者： Ming xu Yong-feng huang Tan Lu Department of Astronomy Nanjing University Nanjing 210093 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

A long plateau phase and an amazing level of brightness have been observed in the X-ray afterglow of GRB 060729. This peculiar light curve is likely due to longterm energy injection in external shock. Here, we present a detailed numerical study of the energy injection process of magnetic dipole radiation from a strongly magnetized millisecond pulsar and model the multi-band afterglow observations. It is found that this model can successfully explain the long plateaus in the observed X-ray and optical afterglow light curves. The sharp break following the plateaus could be due to the rapid decline of the emission power of the central pulsar. At an even later time （～ 5×10^6 s）, an obvious jet break appears, which implies a relatively large half opening angle of θ ～ 0.3 for the GRB ejecta. Due to the energy injection, the Lorentz factor of the outflow is still larger than two even at 10^7 s after the GRB trigger, making the X-ray afterglow of this burst detectable by Chandra even 642 d after the burst.

关键词： gamma rays: bursts -- ISM: jets and outflows

Charged torus-like black holes as heat engines

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2021年第4期73卷 104-110页

作者： Hanwen feng Yuchen huang Wei Hong jun Tao Center for Theoretical Physics College of PhysicsSichuan UniversityChengdu610064China

We investigate the thermodynamical properties of charged torus-like black holes and take it as the working substance to study the heat *** the extended phase space,by interpreting the cosmological constant as the thermodynamic pressure,we derive the thermodynamical quantities by the first law of black hole thermodynamics and obtain the equation of ***,we calculate the efficiency of the heat engine in the Carnot cycle as well as the rectangular cycle,and investigate how the efficiency changes with respect to *** addition,to avoid a negative temperature,we emphasize that the charge of this black hole cannot be ***,we check the calculation accuracy of a benchmark scheme and discuss the upper bound and lower bound for charged torus-like black hole in the scheme.

关键词： charged torus-like black holes heat engines benchmark scheme

Multiple α sub-variants and anisotropic mechanical properties of an additively-manufactured Ti-6Al-4V alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第11期70卷 113-124页

作者： Yinling Zhang Zhuo Chen Shoujiang Qu Aihan feng Guangbao Mi jun Shen xu huang Daolun Chen School of Materials Science and Engineering Tongji UniversityShanghai 201804China Department of Mechanical and Industrial Engineering Ryerson UniversityTorontoOntario M5B 2K3Canada Aerospace Hiwing(Harbin)Titanium Industrial Co. Ltd.Harbin High Tech ZoneHarbin 150028China Shanghai Key Lab.of D&A for Metal-Functional Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys AECC Beijing Institute of Aeronautical MaterialsBeijing 100095China College of Mechatronics and Control Engineering Shenzhen UniversityShenzhen 518060China

Additive manu facturing(AM)is a promising material processing method which gains significant momentum in the aerospace and biomedical ***,the anisotropy in the mechanical properties of additively-manufactured materials is still poorly *** study was aimed at elucidating crystallographic feature-anisotropy-mechanical property relationship for a Ti-6Al-4V alloy manufactured via selective electron beam melting(SEBM).Abundantαlamellae with six variants were present inside the columnar prior-βgrains with afiber texture duringβ→αphase *** sixαvariants followed the Burgers orientation relationship of{110}_(β)//{0001}_(α)and_(β)//_(α).Multiple sub-variants in eachαvariant were observed for the first *** anisotropy in the mechanical properties was mainly related to the relative amount of sixα*** the horizontally-oriented samples had a lower yield strength,they exhibited a higher ductility and longer fatigue life than the vertically-oriented *** softening occurred at higher strain amplitudes,and cyclic stabilization sustained at lower strain *** crack mainly initiated from the specimen surface at lower strain amplitudes,while multiple crack initiation tended to occur at higher strain *** propagation was characterized by fatigue striations along with some secondary cracks.

关键词： Titanium alloy 3D printing Deformation behavior Anisotropy Burgers orientation relationship

Application of split Hopkinson tension bar technique to the study of dynamic fracture properties of materials

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第2期28卷 424-431页

作者： Ze-Jian xu Yu-Long Li feng-Lei huang State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology100081 BeijingChina School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

A novel approach is proposed in determining dy- namic fracture toughness （DFT） of high strength steel, using the split Hopkinson tension bar （SHTB） apparatus, com- bined with a hybrid experimental-numerical method. The center-cracked tension specimen is connected between the bars with a specially designed fixture device. The fracture initiation time is measured by the strain gage method, and dynamic stress intensity factors （DSIF） are obtained with the aid of 3D finite element analysis （FEA）. In this approach, the dimensions of the specimen are not restricted by the connec- tion strength or the stress-state equilibrium conditions, and hence plane strain state can be attained conveniently at the crack tip. Through comparison between the obtained results and those in open publication, it is concluded that the ex- perimental data are valid, and the method proposed here is reliable. The validity of the obtained DFT is checked with the ASTM criteria, and fracture surfaces are examined at the end of paper.

关键词： Split Hopkinson tension bar Dynamic fracture toughness Hybrid experimental-numerical method High loading rate Failure mode

Influence of fruit maturity and lactic fermentation on physicochemical properties,phenolics,volatiles,and sensory of mulberry juice

在线全文

学校读者我要写书评

暂无评论

Food Bioscience 2022年第4期48卷 357-367页

作者： Kunhua Wang jing Qi Yu Jin feng Li jun Wang Huaide xu College of Food Science and Engineering Northwest A&F UniversityYangling712100China

Mulberry fruits harvested at commercial ripeness were sorted into five maturity groups(S1-S5)according to their density,and their juices were separately fermented at 37◦C for 36 h using Lactobacillus plantarum strain *** physicochemical properties,phenolic profile,antioxidant activity,flavor profile,and sensory characteristics of mulberry juice(MJ)were then *** findings revealed that MJs were suitable matrices for LP-01 growth,particularly for MJ-S5 with a high content of phenolics,glucose,and fructose,with more than 12 log CFU/mL of viable counts and 19.64 mg/mL of lactic acid at the end of *** acid bacteria(LAB)fermentation dramatically increased total phenolics,total flavonoids,and antioxidant capacities,while promoting anthocyanin transformation of ***,cyanidin-3-O-glucoside(C3G)was significantly decreased by LAB fermentation and negatively correlated with caffeic and chlorogenic acid contents(p<0.05).Lp-01 fermentation enhanced the total aroma content and complexity of flavor,specifically in MJ-S5 which resulted in the total aroma content increased by 54.96 mg/L and 11 new flavor volatiles ***,MJ-S3 fermentation product was the most attractive for *** results will be valuable in controlling of mulberries product quality precisely.

关键词： Morus nigra Maturity stages Lactic fermentation Physicochemical property Flavor volatiles Sensory evaluation

High-temperature friction behavior of amorphous carbon coating in glass molding process

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

Friction 2021年第6期9卷 1648-1659页

作者： Kangsen LI Gang xu Xiaobin WEN jun ZHOU feng GONG Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China Shenzhen Kingmag Precision Techonology Co.LTD. Shenzhen 518172China

In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated *** improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron *** friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the ***,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high ***,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction *** friction coefficient between the glass and coating depended on the ***,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition *** work provides a better understanding of the application of carbon coatings in the glass molding.

关键词： glass molding process high temperature friction behavior amorphous carbon coating

Numerical simulation and cause analysis of persistent summer drought during the 1920s in eastern China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2022年第5期65卷 966-982页

作者： Meng LUO Jinming feng Zhongfeng xu jun WANG Li DAN Yunnan Climate Center Kunming 650034China Key Lab of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

In the late 1920’s,a mega-drought in China resulted in widespread crop failure and *** evidence suggests that this drought belonged to a dry period ranging from approximately 1922 to *** understand the characteristics and the cause of this persistent drought period,we combined various data,including observations,tree ring proxy data,reanalysis data,simulation results of the Fifth Phase of the Coupled Model Intercomparison Project and numerical downscaling *** results show that during 1922-1932,most regions in eastern China suffered from a persistent drought that lasted for six years,and the maximum negative precipitation anomaly reached−1.5 times the standard *** its spatial coverage,duration,and strength,the 1920s drought was unique for the 20th *** 1920s drought was primarily caused by internal *** easterlies in lower latitudes,strong monsoon circulation,and abnormally high geopotential heights at middle and upper levels were responsible for the 1920s drought conditions in eastern China;these drought conditions could be further attributed to the joint impact of the Atlantic Multidecadal Oscillation,Pacific Decadal Oscillation and Indian Ocean Basin Mode.

关键词： Drought 1920s Eastern China East Asia Summer Monsoon Regional Climate Model Atlantic Multidecadal Oscillation Pacific Decadal Oscillation Indian Ocean Basin Mode

Performance Analysis of a Combined Absorption Refrigeration-Liquid Desiccant Dehumidification THIC System Driven by Low-Grade Heat Source

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2020年第5期29卷 1193-1205页

作者： xu Cong SUI jun DAI Yuze LIU feng LIU Hao Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas,and it is difficult to achieve simultaneous control of temperature and humidity.A combined absorption refrigeration(AR)and liquid desiccant dehumidification(LDD)air-conditioning system based on cascade utilization of low-grade heat source is *** system can realize independent control of temperature and humidity and carry out profound recovery of low-grade heat *** the design conditions,the heat utilization rate C reaches 21.05%,which is 2.73 times that of the conventional absorption refrigeration reference system.A parametric sensitivity analysis is performed to optimize the *** C increases from 9.79%to 18.55%and the coefficient of performance C O P t increases from 0.33 to 0.35 with an increase in chilled water temperature from 7°C to 15°*** an increase in regenerant solution temperature from 60°C to 70°C,the C achieves the optimal value of 21.05%at 68°C.C decreases from 21.05%to 15.05%as the concentration of the regenerant solution increases from 36%to 40%.Under variable environmental temperature and humidity,the C the proposed system changes within a small range and stays much higher than that of the reference system with the same quality heat source,which indicates that the proposed system has a better adaptability to changing environmental parameters.

关键词： temperature and humidity independent control(THIC) low-grade heat source cascade utilization heat utilization rate