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transfer function measurement for the SSRF SRF system

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Nuclear Science and Techniques 2019年第6期30卷 129-137页

作者： Yang-Yang Xia Zhen-Tang Zhao Yu-Bin Zhao Xiang Zheng Kai Xu Zhi-Gang Zhang Shen-Jie Zhao Qiang Chang Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049 China

A digital transfer function measurement system has been embedded in the low-level radio frequency (LLRF) system of the storage ring of the Shanghai Synchrotron Radiation Facility. The measurement results indicate that the decreased control accuracy at high current is primarily owing to ripples from the high-voltage power supply, the transient beam loading effect, and the digital aliasing effect. The current LLRF algorithm is not able to suppress these disturbances.

关键词： transfer function Ripples of HVPS Transient beam loading effect

transfer matrix method for multibody systems(Rui method) and its applications

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Science China(Technological Sciences) 2019年第5期62卷 712-720页

作者： RUI XiaoTing WANG Xun ZHOU QinBo ZHANG JianShu Institute of Launch Dynamics Nanjing University of Science and Technology

The transfer matrix method for multibody systems, namely the "Rui method", is a new method for studying multibody system dynamics, which avoids the global dynamics equations of the system, keeps high computational speed, and allows highly formalized programming. It has been widely applied to scientific research and key engineering of lots of complex mechanical systems in 52 research directions. The following aspects regarding the transfer matrix method for multibody systems are reviewed systematically in this paper: history, basic principles, formulas, algorithm, automatic deduction theorem of overall transfer equation, visualized simulation and design software, highlights, tendency, and applications in 52 research directions in over 100 key engineering products.

关键词： multibody system dynamics transfer matrix method for multibody systems Rui method automatic deduction theorem of overall transfer equation theory computation software applications

transfer synthetic over-sampling for class-imbalance learning with limited minority class data

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Frontiers of Computer Science 2019年第5期13卷 996-1009页

作者： Xu-Ying LIU Sheng-Tao WANG Min-Ling ZHANG School of Computer Science and Engineering Southeast University Nanjing 210096 China Key Laboratory of Computer Network and Information Integration (Southeast University) Ministry of Education Nanjing 210096 China Collaborative Innovation Center for Wireless Communications Technology Nanjing 210096 China

The problem of limited minority class data is encountered in manyclass imbalanced applications, but has received little attention. Synthetic over-sampling, as popular class-imbalance learning methods, could introduce much noise when minority class has limited data since the synthetic samples are not i.i.d. samples of minority class. Mos t sophisticated synthetic sampling methods tackle this problem by denoising or generating samples more consistent with ground-truth data distribution. But their assumptions about true noise or ground-truth data distribution may not hold. To adapt synthetic sampling to the problem of limited minority class data, the proposed Traso framework treats synthetic minority class samples as an additional data source, and exploits transfer learning to transfer knowledge from them to minority class. As an implementation, TrasoBoost method firstly generates synthetic samples to balance class sizes. Then in each boosting iteration, the weights of synthetic samples and original data decrease and increase respectively when being misclassified, and remain unchanged otherwise. The misclassified synthetic samples are potential noise, and thus have smaller influence in the following iterations. Besides, the weights of minority class instances have greater change than those of majority class instances to be more influential. And only original data are used to estimate error rate to be immune from noise. Finally, since the synthetic samples are highly related to minority class, all of the weak learners are aggregated for prediction. Experimental results show TrasoBoost outperforms many popular class-imbalance learning methods.

关键词： machine learning data mining class imbalance over sampling boosting transfer learning

transfer Hierarchical Attention Network for Generative Dialog System

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International Journal of Automation and computing 2019年第6期16卷 720-736页

作者： Xiang Zhang Qiang Yang Computer Science and Engineering Department Hong Kong University of Science and Technology

In generative dialog systems, learning representations for the dialog context is a crucial step in generating high quality responses. The dialog systems are required to capture useful and compact information from mutually dependent sentences such that the generation process can effectively attend to the central semantics. Unfortunately, existing methods may not effectively identify importance distributions for each lower position when computing an upper level feature, which may lead to the loss of information critical to the constitution of the final context representations. To address this issue, we propose a transfer learning based method named transfer hierarchical attention network(THAN). The THAN model can leverage useful prior knowledge from two related auxiliary tasks, i.e.,keyword extraction and sentence entailment, to facilitate the dialog representation learning for the main dialog generation task. During the transfer process, the syntactic structure and semantic relationship from the auxiliary tasks are distilled to enhance both the wordlevel and sentence-level attention mechanisms for the dialog system. Empirically, extensive experiments on the Twitter Dialog Corpus and the PERSONA-CHAT dataset demonstrate the effectiveness of the proposed THAN model compared with the state-of-the-art methods.

关键词： Dialog system transfer learning deep learning natural language processing(NLP) artificial intelligence

transfer of mitochondria from mesenchymal stem cells derived from induced pluripotent stem cells attenuates hypoxia-ischemia-induced mitochondrial dysfunction in PC12 cells

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Neural Regeneration Research 2020年第3期15卷 464-472页

作者： Yan Yang Gen Ye Yue-Lin Zhang Hai-Wei He Bao-Qi Yu Yi-Mei Hong Wei You Xin Li Department of Emergency Medicine Department of Emergency and Critical Care MedicineGuangdong Provincial People’s HospitalGuangdong Academy of Medical SciencesGuangzhouGuangdong ProvinceChina Department of Emergency the First Affiliated HospitalSun Yat-sen UniversityGuangzhouGuangdong ProvinceChina Shantou University Medical College ShantouGuangdong ProvinceChina Department of Physiology and Pathophysiology School of Basic Medical SciencesCapital Medical UniversityKey Laboratory of Remodelling-related Cardiovascular DiseasesMinistry of EducationBeijingChina

Mitochondrial dysfunction in neurons has been implicated in hypoxia-ischemia-induced brain *** mesenchymal stem cell therapy has emerged as a novel treatment for this pathology,the mechanisms are not fully *** address this issue,we first co-cultured 1.5×10^5 PC12 cells with mesenchymal stem cells that were derived from induced pluripotent stem cells at a ratio of 1:1,and then intervened with cobalt chloride(CoCl2)for 24 *** oxygen species in PC12 cells was measured by *** membrane potential(ΔΨm)in PC12 cells was determined by JC-1 *** of PC12 cells was detected by terminal deoxynucleotidal transferase-mediated dUTP nick end-labeling *** morphology in PC12 cells was examined by transmission electron *** of mitochondria from the mesenchymal stem cells derived from induced pluripotent stem cells to damaged PC12 cells was measured by flow *** stem cells were induced from pluripotent stem cells by lentivirus infection containing green fluorescent protein in *** they were co-cultured with PC12 cells in Transwell chambers and treated with CoCl2 for 24 hours to detect adenosine triphosphate level in PC12 ***2-induced PC12 cell damage was ***-culture with mesenchymal stem cells significantly reduced apoptosis and restoredΔΨm in the injured PC12 cells under CoCl2 ***-culture with mesenchymal stem cells ameliorated mitochondrial swelling,the disappearance of cristae,and chromatin margination in the injured PC12 *** direct co-culture,mitochondrial transfer from the mesenchymal stem cells stem cells to PC12 cells was detected via formed tunneling nanotubes between these two types of *** transfer efficiency was greatly enhanced in the presence of *** importantly,inhibition of tunneling nanotubes partially abrogated the beneficial effects of mesenchymal stem cells on CoCl2-induced PC12 cell injury.M

关键词： apoptosis brain injury hypoxia-ischemia induced pluripotent stem cells mesenchymal stem cells mitochondrial membrane potential mitochondrial transfer PC12 cells tunneling nanotubes

transfer matrices of dipoles with bending radius variation

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Science China(Physics,Mechanics & Astronomy) 2011年第S2期54卷 182-184页

作者： PENG YueMei XU Gang Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China

With the increasing demand of high brightness in light source, the uniform dipole can not meet the needs of low emittance, and thus the dipole with bending radius variation is introduced in this paper. The transfer matrix of a non-uniform dipole whose bending radius is linearly changed is chosen as an example and a very simple calculation formula of non-uniform dipole transfer matrices is given. The transfer matrices of some common profile non-uniform dipoles are also listed. The comparison of these transfer matrices and the matrices calculated with slices method verifies the numerical accuracy of this formula. This method can make the non-uniform beam dynamic problem simpler, very helpful for emittance research and lattice design with non-uniform dipoles.

关键词： emittance transfer matrix non-uniform dipole

Effect of CeO_2 on heat transfer and crystallization behavior of rare earth alloy steel mold fluxes

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 565-572页

作者： Ze-yun Cai Bo Song Long-fei Li Zhen Liu Xiao-kang Cui School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

To improve the heat transfer capability and the crystallization property of the traditional mold flux, CaF_2 was replaced with B_2O_3. Then, the influences of CeO_2 on the heat transfer and the crystallization of the CaF_2-bearing mold flux and the new mold flux with 10 wt% B_2O_3 were studied using a slag film heat flux simulator and X-ray diffraction(XRD). The results revealed that the addition of CeO2 reduced the heat transfer by increasing the solid slag thickness and the crystallization of two mold fluxes. However, CeO_2 had less effect on the B_2O_3-containing mold flux compared with the CaF_2-bearing mold flux. According to the analyses, the CeO_2 contents in the CaF_2-bearing mold flux and the B_2O_3-containing mold flux should not exceed 8 wt% and 12 wt%, respectively. Therefore, these experimental results are beneficial to improve and develop the mold flux for casting rare earth alloy steels.

关键词： cerium oxide boron trioxide mold fluxes heat transfer crystallization rare earth alloy steels

Heat transfer in a tapered fluidized bed of biomass particles with pulsed gas flow

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Particuology 2019年第1期17卷 2-14页

作者： Dening Jia Xiaotao Bi C. Jim Lim Shahab Sokhansanj Atsushi Tsutsumi Department of Chemical and Biological Engineering The University of British Columbia2360 East MallVancouverBCV6T 1Z3Canada Environmental Sciences Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Collaborative Research Center for Energy Engineering Institute of Industrial ScienceThe University of Tokyo4-6-1 KomabaMeguro-kuTokyo 153-8505Japan

Bed-to-surface heat transfer of pure biomass particles in a pulsed fluidized bed with a tapered bottom section was investigated. Three biomass species — Douglas fir, pine, and switchgrass — were studied under various operating conditions. Their heat transfer coefficients were found to be closely associated with hydrodynamics dominated by gas pulsations. A higher superficial gas velocity generally yielded better gas–solid contact and higher heat transfer rates. A moderately increasing pulsation frequency promoted convective heat transfer of particles but also reduced pulsation intensity, leading to undesired flow behaviours such as channelling and partial defluidization. The study of the pulsation duty cycle revealed that, for cohesive particles, a smaller duty cycle was preferred to generate powerful pulsations to break up inter-particle forces. Moreover, a duty cycle increase allowed higher gas throughput as long as a suitable fluidization was maintained. The addition of finer particles to a coarse fraction increased particle mobility, and subsequently heat transfer, which also explained the higher heat transfer coefficients of switchgrass as it contained more fines compared with fir and pine. Experimental results in the tapered bed were also compared with those of non-tapered geometry where a 10%–20% increase in heat transfer was observed.

关键词： Fluidized bed Gas pulsations Tapered column Heat transfer Biomass

Extending the operational lifetimes of all-direct electron transfer enzymatic biofuel cells by magnetically assembling and exchanging the active biocatalyst layers on stationary electrodes

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Nano Research 2019年第4期12卷 767-775页

作者： Katharina Herkendell Andreas Stemmer Ran Tel-Vered Saumerstrasse 4 Nanotechnology Group D-MAVT ETH Zurich Ruschlikon CH-8803 Switzerland

Enzymatic biofuel cells promise green power generation from a variety of natural resources, yet these systems all suffer from time-dependent degradati on effects, in particular progress! ng inactivation of enzymes, which severely limit the operati on al lifetimes of such power sources. To extend operational lifetimes, we introduce a method to magnetically exchange exhausted enzymes for fresh ones. To this end, anodic and cathodic enzymes or enzyme cascades are immobilized on carbon coated magnetic nanoparticles. Under the action of suitable magnetic field gradie nts, these nano particles are assembled on the respective stati onary electrodes, or released from the electrodes for collection and subsequent excha nge. We dem on strate this method on a fructose/oxygen con suming biofuel cell emplo ying fructose dehydroge nase and bilirubin oxidase as well as on anodic and cathodic cascades employing fructose dehydrogenase/invertase and bilirubin oxidase/catalase, respectively. The en zyme-modified nan oparticles support direct electro n transfer bioelectrocatalytic curre nts by wiring the redox active cofactors to the carbonaceous coating and from there to the electrode surfaces. The facile injection, assembly, and removal of enzyme-modified magnetic nan oparticles along with fuel solutio n provides a promisi ng approach to exte nd the operati on al lifetime of enzymatic biofuel cells without the need for exchanging entire systems including chambers and electrodes.

关键词： direct electron transfer magnetic nanoparticle enzymatic biofuel cell recharge lifetime enzyme cascade