检索结果-南通市图书馆

An Offloading Scheme Leveraging on Neighboring Node Resources for Edge Computing over Fiber-Wireless (FiWi) Access Networks

在线全文

学校读者我要写书评

暂无评论

China Communications 2019年第11期16卷 107-119页

作者： wei chang Yihong Hu Guochu Shou Yaqiong Liu Zhigang Guo Beijing Key Laboratory of Network System Architecture and Convergence School of Information and Communication Engineering Beijing University of Posts and Telecommunications

The computation resources at a single node in Edge Computing(EC)are commonly limited,which cannot execute large scale computation *** face the challenge,an Offloading scheme leveraging on NEighboring node Resources(ONER)for EC over Fiber-Wireless(FiWi)access networks is proposed in this *** the ONER scheme,the FiWi network connects edge computing nodes with fiber and converges wireless and fiber connections seamlessly,so that it can support the offloading transmission with low delay and wide *** on the ONER scheme supported by FiWi networks,computation tasks can be offloaded to edge computing nodes in a wider range of area without increasing wireless hops(e.g.,just one wireless hop),which achieves low ***,an efficient Computation Resource Scheduling(CRS)algorithm based on the ONER scheme is also proposed to make offloading *** results show that more offloading requests can be satisfied and the average completion time of computation tasks decreases significantly with the ONER scheme and the CRS ***,the ONER scheme and the CRS algorithm can schedule computation resources at neighboring edge computing nodes for offloading to meet the challenge of large scale computation tasks.

关键词： edge computing offloading Fiber-wireless access networks delay

Stochastic normalized gradient descent with momentum for large-batch training

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第11期67卷 77-91页

作者： Shen-Yi ZHAO chang-wei SHI Yin-Peng XIE Wu-Jun LI National Key Laboratory for Novel Software Technology Department of Computer Science and TechnologyNanjing University

Stochastic gradient descent(SGD) and its variants have been the dominating optimization methods in machine learning. Compared with SGD with small-batch training, SGD with large-batch training can better utilize the computational power of current multi-core systems such as graphics processing units(GPUs)and can reduce the number of communication rounds in distributed training settings. Thus, SGD with large-batch training has attracted considerable attention. However, existing empirical results showed that large-batch training typically leads to a drop in generalization accuracy. Hence, how to guarantee the generalization ability in large-batch training becomes a challenging task. In this paper, we propose a simple yet effective method, called stochastic normalized gradient descent with momentum(SNGM), for large-batch training. We prove that with the same number of gradient computations, SNGM can adopt a larger batch size than momentum SGD(MSGD), which is one of the most widely used variants of SGD, to converge to an?-stationary point. Empirical results on deep learning verify that when adopting the same large batch size,SNGM can achieve better test accuracy than MSGD and other state-of-the-art large-batch training methods.

关键词： non-convex problems large-batch training stochastic normalized gradient descent momentum

Effect of Sm-doping on the morphology and magnetic properties of radio frequency magnetron sputtered Ni-Mn-Ga films

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第6期19卷 555-560页

作者： Feng-hua Chen Min-gang Zhang Yue-sheng Chai chang-wei Gong College of Materials Science and Engineering Taiyuan University of Science and Technology Talyuan 030024 China

Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sml films were prepared by radio frequency （RF） magnetron sputtering. The effect of Sm do- pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated. Sm doping can refine the particle size of the films from 100 to 60 nm, and further grain growth is not occurs even after annealing at 1073 K for 3.6 ks. Compared to Ni55.5Mn21Ga23.5 films, Sm-doped Ni54Mn22Ga23Sml films are easier to be magnetized and have a lower martensitic transformation temperature. In addition, the Curie temperature can also be adjusted, decreasing from 350 to 325 K after Sm doping. Martensitic transformation is not observed in the Sm-free films, which is close to the Curie temperature in the Sm-doped films, giving rise to the overlap of the structural and magnetic transi- tion temperatures.

关键词： magnetic films samarium doping magnetron sputtering martensitic transformation magnetic transition temperature magneticproperties rare earths

ECG quality assessment based on a kernel support vector machine and genetic algorithm with a feature matrix

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第7期15卷 564-573页

作者： Ya-tao ZHANG Cheng-yu LIU Shou-shui wei chang-zhi wei Fei-fei LIU School of Control Science and Engineering Shandong University School of Mechanical Electrical & Information Engineering Shandong University Institute of Cellular Medicine Newcastle University

We propose a systematic ECG quality classification method based on a kernel support vector machine(KSVM) and genetic algorithm(GA) to determine whether ECGs collected via mobile phone are acceptable or not. This method includes mainly three modules, i.e., lead-fall detection, feature extraction, and intelligent classification. First, lead-fall detection is executed to make the initial classification. Then the power spectrum, baseline drifts, amplitude difference, and other time-domain features for ECGs are analyzed and quantified to form the feature matrix. Finally, the feature matrix is assessed using KSVM and GA to determine the ECG quality classification results. A Gaussian radial basis function(GRBF) is employed as the kernel function of KSVM and its performance is compared with that of the Mexican hat wavelet function(MHWF). GA is used to determine the optimal parameters of the KSVM classifier and its performance is compared with that of the grid search(GS) method. The performance of the proposed method was tested on a database from PhysioNet/Computing in Cardiology Challenge 2011, which includes 1500 12-lead ECG recordings. True positive(TP), false positive(FP), and classification accuracy were used as the assessment indices. For training database set A(1000 recordings), the optimal results were obtained using the combination of lead-fall, GA, and GRBF methods, and the corresponding results were: TP 92.89%, FP 5.68%, and classification accuracy 94.00%. For test database set B(500 recordings), the optimal results were also obtained using the combination of lead-fall, GA, and GRBF methods, and the classification accuracy was 91.80%.

关键词： ECG quality assessment Kernel support vector machine Genetic algorithm Power spectrum Cross validation

Effect of oxygen enrichment on sintering behavior of high proportion vanadium-titanium magnesite concentrates

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第11期30卷 2122-2132页

作者： Shi-hong Peng Hao Liu Ze-zheng Sun chang-wei Li Yue-lin Qin wei-qiang Liu Guang Wang School of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing401331China Value-Added Process and Clean Extraction of Complex Metal Mineral Resources Chongqing Municipal Key Laboratory of Institutions of Higher EducationChongqing401331China Chongqing Chuanyi Automation Co. Ltd.Chongqing401120China Process and Systems Engineering Åbo Akademi UniversityÅbo20500Finland Department of Materials Science and Engineering McMaster UniversityOntarioL8S 4L7Canada

To achieve high-efficiency utilization of complex and unmanageable iron-containing minerals,the effects of oxygen enrichment on productivity,yield,flame front speed,exhaust gas peak temperature,and desulphurization reaction of the vanadium-titanium magnetite sintering process as well as sinter tumble index and mineralogy were clarified,with oxygen enrichment concentrations ranging from 21 to 29 vol.%.Results indicated that with increasing the oxygen enrichment concentration from 21 to 27 vol.%,the flame front speed increased from 30.3 to 40.0 mm min^(-1),the yield enhanced from 72%to 77%,and the productivity augmented from 1.83 to 2.67t m^(-2)h^(-1);in the meantime,the tumble index was improved from 73.7%to 77.9%,and the exhaust gas peak temperature rose from 376.4 to 484.8℃.The main reason for the improvement in sintering properties was the increased combustibility of fuels and the generation of proper liquid phase that improved the permeability of the packed *** improved sinter strength is mainly due to the increase in the phase fraction of silico-ferrites of calcium and *** addition,oxygen enrichment sintering could significantly increase the desulphurization level of vanadium-titanium magnetite sinter and the rate of desulphurization reaction during sintering process.

关键词： Sinter Oxygen enrichment Vanadium-titanium magnetite Sintering behavior

Electrolytic Passivation of Nitinol Shape Memory Alloy in Different Electrolytes

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 2006年第B12期19卷 113-118页

作者： SU Xiang-dong WANG Tian-min HAO wei-chang HE Li Center of Materials Physics and Chemistry Beijing University of Astronautics and Aeronautics Beijing 100083 China Guizhou Academy of Science Guiyang 55000 China

The corrosion behavior of the nitinol alloy was studied in various corrosion media of different Cl^- ion concentrations. The results demonstrate that the Cl^- ion concentration has significant influences on the corrosion behavior of the nitinol alloy. In order to enhance the corrosion resistance, protective films were generated on the surface of the nitinol alloy by means of the electrochemical passivation method, for which five different electrolytic solutions were investigated. The surface analysis indicates full growth of all samples passivated in the different electrolytic solutions with layers, however, showing different morphological features. Without any defects like micro-cracks and pores, the surface of the samples passivated in the molybdate solution turns out smoother and denser than those passivated in other solutions. It is shown that the electro-chemical passivation will reduce Ni content but increase Ti content in the surface, reaching the Mole ratio of Ti：Ni = 9.01：1 on the outermost surface. Potentiodynamic polarization test demonstrates that the samples electrochemically passivated in the molybdate solution present a significant increase in breakdown potential due to titanium enrichment on the outermost surface.

关键词： NiTi alloy Cl^- ion corrosion electrolytic passivation TiO2 coating

Electrochemical impedance spectroscopy study on the corrosion of the weld zone of 3Cr steel welded joints in CO_2 environments

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2015年第5期22卷 500-508页

作者： Li-ning Xu Jin-yang Zhu Min-xu Lu Lei Zhang wei chang Corrosion and Protection Center Key Laboratory for Environmental Fracture (MOE) Institute for Advanced Materials and Technology University of Science and Technology Beijing CNOOC Research Institute

The welded joints of 3Cr pipeline steel were fabricated with commercial welding wire using the gas tungsten arc welding （GTAW） technique. Potentiodynamic polarization curves, linear polarization resistance （LPR）, electrochemical impedance spectroscopy （EIS）, scan- ning electron microscopy （SEM）, and energy-dispersive spectrometry （EDS） were used to investigate the corrosion resistance and the growth of a corrosion film on the weld zone （WZ）. The changes in electrochemical characteristics of the film were obtained through fitting of the EIS data. The results showed that the average corrosion rate of the WZ in CO2 environments first increased, then fluctuated, and finally de- creased gradually. The formation of the film on the WZ was divided into three stages： dynamic adsorption, incomplete-coverage layer forma- tion, and integral layer formation.

关键词： petroleum pipelines steel corrosion welded joints carbon dioxide electrochemical impedance spectroscopy

Ring columns as pier scour countermeasures

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2011年第3期26卷 353-363页

作者： Jen-Hao CHENG Han-Peng SHIH Jen-wei chang Candidate in Program of Civil and Hydraulic Engineering Feng Chia UniversityTaichungTaiwanChina Department of Water Resources Engineering and Conservation The University of Feng ChiaTaiwan.China

Ring columns placed upstream of a bridge pier to protect it from local scouring are typical scouring countermeasures.A series of experiments are conducted under clear-water steady flow（V/V;≤1）with uniform *** parameters,such as ring column diameter,thickness,height,and distances between ring columns and the pier,are considered in the *** data are used to assess the influence of each parameter on pier scour *** results indicate that pores in ring columns provide space for energy dissipation of the downflow,hence,effectively reduce the flow energy impacting the downstream *** friction force of ring columns caused by their geometric shape reduces kinetic energy and pier scour *** general,it is found that the best pattern of ring columns reduce pier scour depth by 65%.

关键词： Ring columns Local scour Energy dissipation Scour depth

Catalytic Synthesis of Hexyl-naphthalene over H-type Zeolites

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2005年第6期21卷 684-686页

作者： wei chang-ping SUN Xiao-fei JIANG Xin-hua ZHEN Kai-ji College of Materials and Chemical Engineering Changchun University of Science and Technology Changchun 130022 P. R. China College of Biological Engineering Changchun University of Technology Changchun 130012 P. R. China Collegc of Chemistry Jilin University Changchun 130023 P. R. China

H-type zeolites（ HY, Hβ, and HM） were synthesized and characterized by XRD, NH3-TPD, and Py-IR. Selectively catalytic alkylation of naphthalene with n-hexanol to hexyl-naphthalene over the zeolites was carried out. The experimental results show that the catalytic activities of the zeolites are mainly determined by their acid properties and pore structures. The larger the pore diameter is, the higher the catalytic activity is. NH3-TPD profiles show that Hβ and HM have lower acid strengths than HY. HY has both the highest activity and highest selectivity for the hexylnaphthalene. Higher reaction temperatures and longer reaction time are beneficial to the production of β-hexyl-naphthalene over the HY zeolite.

关键词： H-type zeolites Naphthalene n-Hexanol Hexylnaphthalene Alkylation