检索结果-南通市图书馆

Application of convolutional neural networks to large-scale naphtha pyrolysis kinetic modeling

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2018年第12期26卷 2562-2572页

作者： Feng hua Zhou Fang Tong qiu Department of Chemical Engineering Tsinghua University Beijing 100084China Beijing Key Laboratory of Industrial Big Data System and Application Beijing 100084China

System design and optimization problems require large-scale chemical kinetic models. Pure kinetic models of naphtha pyrolysis need to solve a complete set of stiff ODEs and is therefore too computational expensive. On the other hand, artificial neural networks that completely neglect the topology of the reaction networks often have poor generalization. In this paper, a framework is proposed for learning local representations from largescale chemical reaction networks. At first, the features of naphtha pyrolysis reactions are extracted by applying complex network characterization methods. The selected features are then used as inputs in convolutional architectures. Different CNN models are established and compared to optimize the neural network *** the pre-training and fine-tuning step, the ultimate CNN model reduces the computational cost of the previous kinetic model by over 300 times and predicts the yields of main products with the average error of less than 3%. The obtained results demonstrate the high efficiency of the proposed framework.

关键词： Convolutional neural network Network motif Naphtha pyrolysis Kinetic modeling

Transient stochastic response of quasi integerable Hamiltonian systems

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第4期29卷 602-611页

作者： Zhong-hua Liu Jian-hua Geng Wei-qiu Zhu Department of Civil Engineering Xiamen University Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University

The approximate transient response of quasi in- tegrable Hamiltonian systems under Gaussian white noise excitations is investigated. First, the averaged It6 equa- tions for independent motion integrals and the associated Fokker-Planck-Kolmogorov （FPK） equation governing the transient probability density of independent motion integrals of the system are derived by applying the stochastic averag- ing method for quasi integrable Hamiltonian systems. Then, approximate solution of the transient probability density of independent motion integrals is obtained by applying the Galerkin method to solve the FPK equation. The approxi- mate transient solution is expressed as a series in terms of properly selected base functions with time-dependent coeffi- cients. The transient probability densities of displacements and velocities can be derived from that of independent mo- tion integrals. Three examples are given to illustrate the ap- plication of the proposed procedure. It is shown that the re- suits for the three examples obtained by using the proposed procedure agree well with those from Monte Carlo simula- tion of the original systems.

关键词： Transient response ~ Stochastic averagingmethod ~ Galerkin method ~ Quasi integrable Hamiltoniansystem

Major advances in microbeam analytical techniques and their applications in Earth Science

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2016年第23期61卷 1785-1787页

作者： Xian-hua Li qiu-Li Li State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences

Major breakthroughs in modem Earth Science research largely depend on innovations in observation and analytical techniques. Over the last two decades, there have been great advances in modem microbeam analytical tech- niques, which are widely used in various subject areas in the broad field of Earth Sciences. Remarkable enhancements to observation and analysis techniques at the micro- scale have significantly improved our understanding of the Earth＇s history and its many geological processes.

关键词：微束分析技术地球科学应用科学科学研究微观尺度地质过程

Corrosion behavior of three Ag–50Cu alloys prepared by different processes in NaCl solutions

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2017年第1期36卷 61-68页

作者： Zhong-qiu Jia qiu-Ying liang qiu-Yue Tian Zhong-qiu Cao Yan Wang College of Chemistry-and Chemical Engineering Shenyang Normal University Shenyang 110034 China

Corrosion behavior of two nanocrystalline bulk Ag–50Cu alloys and one coarse-grained counterpart prepared by liquid-phase reduction(LPR), mechanical alloying(MA) and powder metallurgy(PM) methods,respectively, were investigated in Na Cl solutions. They were finished by means of PARM273 A and M5210 electrochemical apparatus through potentiodynamic polarization method and electrochemical impedance spectroscopy(EIS) technique. The results show that corrosion rates of three Ag–50Cu alloys increase with the increment of Na Cl solution concentrations. Corrosion rates of LPRAg–50Cu alloy are a little higher than those of PMAg–50Cu alloy,but evidently lower than those of MAAg–50Cu alloy. The difference in corrosion rates is attributed to the large reduction in the grain size and homogeneous microstructure of nanocrystalline alloys. Passive current densities decrease and afterward increase for PMAg–50Cu alloy,decrease for MAAg–50Cu alloy, and increase for LPRAg–50Cu alloy with the increment of Na Cl solution concentrations. After the grain sizes are refined, passive current densities become lower.

关键词： Copper alloys Corrosion Corrosion rate Corrosive effects Electrochemical corrosion Electrochemical impedance spectroscopy Electrochemistry Grain size and shape Mechanical alloying Nanocrystals Powder metallurgy Reduction Silver Silver alloys

Ultrashort Pulse Generation at Quasi-40-GHz by Using a Two-Section Passively Mode-Locked InGaAsP-InP Tensile Strained Quantum-Well Laser

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2012年第2期29卷 83-85页

作者： KONG Duan-hua ZHU Hong-liang liang Song qiu Ji-Fang ZHAO Ling-Juan Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083

A 1.56 μm passively mode-locked laser diode with a two-section tensile strained multi-quantum-well structure is *** any external pulse compression,a Lorentz pulse train with a pulse width of 1.03 ps and a repetition rate of 35.6 GHz is obtained,which is one of the best results that have been reported on similar *** optical pulse has a 300 kHz line width and a 50dB peak over the noise floor in the photodetected radio-frequency electrical spectrum.

关键词： pulse passive Quantum

Environmental factors influencing the distribution of total and fecal coliform bacteria in six water storage reservoirs in the Pearl River Delta Region,China

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

Journal of Environmental Sciences 2010年第5期22卷 663-668页

作者： huachang Hong Jianwen qiu Yan liang College of Geography and Environmental Sciences Zhejiang Norraal University Jinhua 321004 China Croucher Institute for Environmental Sciences and the Department of Biology Hong Kong Baptist University Kowloon Tong Hong Kong China

The Pearl River Delta （PRD） is one of the most developed and densely populated regions in *** the amount of pathogens in the source of drinking water is important for improving water *** collected water samples from six major water storage reservoirs in the PRD region in both wet and dry seasons in *** showed that external environmental factors,such as precipitation,location,as well as the internal environmental factors,i.e.,physicochemical properties of the water,were closely related with the distribution of ***,the coliform bacterial concentrations in wet season were one to two orders of magnitude greater than those in dry ***,coliform bacterial levels in reservoirs near urban and industrial areas were significantly higher （p 〈 0.05） than those in remote *** analyses showed that the levels of coliforms had close relationships with pH,temperature,suspended solid,organic and inorganic nutrients in *** components analysis further demonstrated that total coliforms in the reservoirs were closely related with water physicochemical properties,while fecal coliforms were more associated with external input brought in by seasonal runoff.

关键词： coliform bacteria location rainfall physicochemical parameters reservoir

Distributional Dimension of Fractal Sets in Local Fields

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2008年第1期24卷 147-158页

作者： hua qiu Wei Yi SU Department of Mathematics Nanjing University Nanjing 210093 P. R. China

The distributional dimension of fractal sets in R^n has been systematically studied by Triebel by virtue of the theory of function spaces. In this paper, we first discuss some important properties about the B-type spaces and the F-type spaces on local fields, then we give the definition of the distributional dimension dimD in local fields and study the relations between distributional dimension and Hausdorff dimension. Moreover, the analysis expression of the Hausdorff dimension is given. Lastly, we define the Fourier dimension in local fields, and obtain the relations among all the three dimensions. Keywords local field, B-type space, F-type space, distributional dimension, Hausdorff dimension Fourier dimension

关键词： local field B-type space F-type space distributional dimension Hausdorff dimension,Fourier dimension

Neuroprotective effects of neural stem cells pretreated with neuregulin1β on PC12 cells exposed to oxygen-glucose deprivation/reoxygenation

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2023年第3期18卷 618-625页

作者： qiu-Yue Zhai Yuan-hua Ye Yu-Qian Ren Zhen-hua Song Ke-Li Ge Bao-He Cheng Yun-liang Guo Institute of Cerebrovascular Diseases Medical Research CenterThe Affiliated Hospital of Qingdao UniversityTaishan Scholars Construction Project Excellent Innovative Team of Shandong ProvinceQingdaoShandong ProvinceChina Department of Obstetrics The Affiliated Hospital of Qingdao UniversityQingdaoShandong ProvinceChina Research Center of Stem Cells Shandong Haoyun International Hospital of Stem CellsJinanShandong ProvinceChina

Studies on ischemia/reperfusion(I/R)injury suggest that exogenous neural stem cells(NSCs)are ideal candidates for stem cell therapy reperfusion ***,NSCs are difficult to obtain owing to ethical *** addition,the survival,differentiation,and proliferation rates of transplanted exogenous NSCs are low,which limit their clinical *** previous study showed that neuregulin1β(NRG1β)alleviated cerebral I/R injury in *** this study,we aimed to induce human umbilical cord mesenchymal stem cells into NSCs and investigate the improvement effect and mechanism of NSCs pretreated with 10 nM NRG1βon PC12 cells injured by oxygen-glucose deprivation/reoxygenation(OGD/R).Our results found that 5 and 10 nM NRG1βpromoted the generation and proliferation of ***-culture of NSCs and PC12 cells under condition of OGD/R showed that pretreatment of NSCs with NRG1βimproved the level of reactive oxygen species,malondialdehyde,glutathione,superoxide dismutase,nicotinamide adenine dinucleotide phosphate,and nuclear factor erythroid 2-related factor 2(Nrf2)and mitochondrial damage in injured PC12 cells;these indexes are related to *** has reported that p53 and solute carrier family 7 member 11(SLC7A11)play vital roles in ferroptosis caused by cerebral I/R *** data show that the expression of p53 was increased and the level of glutathione peroxidase 4(GPX4)was decreased after RNA interference-mediated knockdown of SLC7A11 in PC12 cells,but this change was alleviated after co-culturing NSCs with damaged PC12 *** findings suggest that NSCs pretreated with NRG1βexhibited neuroprotective effects on PC12 cells subjected to OGD/R through influencing the level of ferroptosis regulated by p53/SLC7A11/GPX4 pathway.

关键词： ferroptosis p53 SLC7A11 GPX4 human umbilical cord-mesenchymal stem cells neural stem cells neuregulin1β neuroprotection oxygen-glucose deprivation/reoxygenation PC12 cell

Dynamic and Static Recrystallization Behavior of Low Carbon High Niobium Microalloyed Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第1期18卷 55-60页

作者： LAN liang yun qiu Chun lin ZHAO De-wen GAO Xiu hua DU Lin-xiu State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

The recrystallization behavior of a low carbon high niobium microalloyed steel was investigated using continuous and interrupted hot compression tests. The results showed that the initiation of dynamic recrystallization （DRX） could be detected from inflection in the plot of the strain hardening rate against stress regardless of the stress peak appearance. According to the Zener-Hollomon parameter equation, the activity energy of DRX （Qad） was ob tained and a new modified expression calculating Qdef was proposed in consideration of the chemical composition of experimental steel. Applying the 2% offset method, the static softening fraction was determined. The graphic representation of the softening fraction vs interruption time gave the information about the non-static reerystallization temperature （about 1 000℃ ） and the relationship of precipitation time temperature. Static recrystallization kinetics followed the Avrami＇s law at high deformation temperature, and different values of the exponent m were given to illustrate the effect of niobium element on static recrystallization at different deformation temperatures.

关键词： dynamic recrystallization static recrystallization high niobium microalloyed steel activity energy