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An overview of multi-task learning

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National Science Review 2018年第1期5卷 30-43页

作者： yu zhang Qiang Yang Department of Computer Science and Engineering Hong Kong University of Science and Technology

As a promising area in machine learning, multi-task learning(MTL) aims to improve the performance of multiple related learning tasks by leveraging useful information among them. In this paper, we give an overview of MTL by first giving a definition of MTL. Then several different settings of MTL are introduced,including multi-task supervised learning, multi-task unsupervised learning, multi-task semi-supervised learning, multi-task active learning, multi-task reinforcement learning, multi-task online learning and multi-task multi-view learning. For each setting, representative MTL models are presented. In order to speed up the learning process, parallel and distributed MTL models are introduced. Many areas, including computer vision, bio info rmatics, health informatics, speech, natural language processing, web applications and ubiquitous computing, use MTL to improve the performance of the applications involved and some representative works are reviewed. Finally, recent theoretical analyses for MTL are presented.

关键词： multi-task learning

Agrobacterium-mediated delivery of CRISPR/Cas reagents for genome editing in plants enters an era of ternary vector systems

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Science China(Life Sciences) 2020年第10期63卷 1491-1498页

作者： yu zhang Qiang zhang Qi-Jun Chen State Key Laboratory of Plant Physiology and Biochemistry College of Biological SciencesChina Agricultural UniversityBeijing 100193China Center for Crop Functional Genomics and Molecular Breeding China Agricultural UniversityBeijing 100193China

Lack of appropriate methods for delivery of genome-editing reagents is a major barrier to CRISPR/Cas-mediated genome editing in ***-mediated genetic transformation(AMGT)is the preferred method of CRISPR/Cas reagent delivery,and researchers have recently made great improvements to this *** this article,we review the development of AMGT and AMGT-based delivery of CRISPR/Cas *** give an overview of the development of AMGT vectors including binary vector,superbinary vector,dual binary vector,and ternary vector *** also review the progress in Agrobacterium genomics and Agrobacterium genetic engineering for optimal *** focus in particular on the ternary vector system and the resources we *** summary,it is our opinion that Agrobacterium-mediated CRISPR/Cas genome editing in plants is entering an era of ternary vector systems,which are often integrated with morphogenic *** new vectors described in this article are available from Addgene and/or MolecularCloud for sharing with academic investigators for noncommercial research.

关键词： genome editing CRISPR/Cas ternary vector system delivery Agrobacterium-mediated transformation

In situ Remediation of Petroleum Contaminated Groundwater by Permeable Reactive Barrier with Hydrothermal Palygorskite as Medium

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Chemical Research in Chinese Universities 2013年第1期29卷 37-41页

作者： zhang Sheng-yu zhang yu-ling SU Xiao-si zhang Ying Institute of Water Resources and Environmental Key Lab of Groundwater Resources and Environment Ministry of Education Jilin University Changchun 130026 P. R. China

The permeable reactive barrier（PRB） has proven to be a costeffective technique to remediate the petro leum contaminated groundwater at a northeast field site in China. In this study, the geology, hydrogeology and con tamination characterization of the field site were investigated and the natural hydrothermal palygorskite was chosen as a reactive medium. Furthermore, the adsorption of the total petroleum hydrocarbons（TPH） in the groundwater onto hydrothermal palygorskite and the adsorption kinetics were investigated. The results indicate that the removal rates of TPH, benzene, naphthalene and phenantharene could all reach up to 90% by hydrothermal palygorskite with a diameter of 0.25-2.00 mm that had been thermally pretreated at 140 ℃. The adsorption of TPH onto hydrothermal palygorskite after pretreatment followed a pseudosecondorder kinetic model and a Langmuir adsorption isotherm, suggesting that the theoretic adsorption capacity of hydrothermal palygorskite for adsorbate could be 4.2 g/g. Scan ning electron microscopy（SEM）, infrared spectroscopy（IR）, Xray diffraction（XRD） and Xray fluorescence spec troscopy（XRF） were carried out to analyze the adsorption mechanism. The results reveal that hydrothermal palygors kite is a fibrous silicate mineral enriched in Mg and A1 with large surface area and porosity. The dense cluster acicular and fibrous crystal of hydrothermal palygorskite, and its effect polar group OH played an important role in the physical and chemical adsorption processes of it for contaminants. This study has demonstrated hydrothermal paly gorskite is a reliable reactive medium for in situ remediation of petroleum contaminated groundwater at field sites.

关键词： Petroleum contaminated groundwater Hydrothermal palygorskite Total petroleum hydrocarbon(TPH) Adsorption

Variation of Two-photon Absorption Cross Sections and Optical Limiting of Compounds Induced by Static Electric Field

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Chinese Journal of Chemical Physics 2014年第3期27卷 259-264页

作者： yu-jin zhang yu-zhi Song Chuan-kui Wang College of Physics and Electronics Shandong Normal University Jinan 250014 China

By numerically solving the Maxwell-Bloch equations using an iterative predictor-corrector finite-difference time-domain technique, we investigate propagating properties of a few-cycle laser pulse in a 4,4＇-bis（di-n-butylamino） stilbene （BDBAS） molecular medium when a static electric field exists. Dynamical two-photon absorption （TPA） cross sections are obtained and optical limiting （OL） behavior is displayed. The results show that when the static electric field intensity increases, the dynamical TPA cross section is enhanced and the OL behavior is improved. Moreover, both even- and odd-order harmonic spectral components are generated with existence of the static electric field because it breaks the inversion symmetry of the BDBAS molecule. This work provides a method to modulate the nonlinear optical properties of the BDBAS compounds.

关键词： Static electric field Optical limiting Two-photon absorption Organic molecule

Centralized and distributed resource allocation in OFDM based multi-relay system

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第6期11卷 450-464页

作者： Rui YIN yu zhang Guan-ding yu Zhao-yang zhang Jie-tao zhang Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 31002 7 China Wireless Research Department Huawei Technologies Co. Ltd. Shenzhen 518129 China

In the presence of multiple non-regenerative relays, we derived optimal joint power allocation, relay selection, and subchannel pairing schemes in orthogonal frequency division multiplexing(OFDM) based wireless *** Lagrange dual method was employed to design the optimal ***, the optimization problem was formulated for the single-relay system and the optimal centralized algorithm was presented by resolving the dual ***, the optimal algorithm for a multi-relay system was proposed in a similar *** with the exhaustive search method, the computational complexity of the proposed optimal algorithms was reduced from non-polynomial to polynomial ***, the centralized algorithm was extended to the distributed algorithm, which was more feasible for the practical *** results verify our analysis.

关键词： Wireless relay network Orthogonal frequency division multiplexing(OFDM) Relay selection Convex optimization Dual method

Structural and Rheological Properties of PP/EPR/PE Alloys

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Chinese Journal of Polymer Science 2023年第2期41卷 240-249页

作者： Jia-Qi zhang Yan-Jie zhang Chun-yu zhang Quan Chen State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China University of Science and Technology of China Hefei230026China School of Polymer Science and Engineering Qingdao University of Science&TechnologyQingdao266042China

Linear and non-linear rheological properties were examined for in-reactor alloy samples composed of isotactic polypropylene(iPP),ethylene-propylene rubber(EPR),and polyethylene(PE).The samples were prepared through two-or three-stage sequential polymerization,where iPP,as the majority,was synthesized in the first stage,and either EPR or PE,as the minority,was synthesized in the second or third *** Tm of both PE and iPP,the linear viscoelasticity shows two relaxation processes,where the fast and slow processes are attributable to the relaxation of the iPP component and that of the EPR/PE domains,*** the damping behavior upon applying the step-strain measurements and the shear-thinning behavior under the shear-rate sweep measurements are strongly related to the different degrees of nonlinearity of the two relaxation processes.

关键词： Polypropylene alloy Structure Nonlinear rheology

Interior non-uniformity of acoustically excited oscillating gas bubbles

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Journal of Hydrodynamics 2019年第4期31卷 725-732页

作者： yu-ning zhang Xiao-fei Li Zhong-yu Guo Key Laboratory of Condition Monitoring and Control for Power Plant Equipment (Ministry of Education) School of Energy Power and Mechanical Engineering North China Electric Power University Beijing 102206 China Key Labor at oiy of Fluid and Power Machinery Ministry of Education Xihua IJnivarsily Chengdu 610039 China College of Mechanical and Transportation Engineering China University of Petroleum-Beijing Beijing 102249 China Beijing Key Laboratory of Process Fluid Filtration and Separation China University of Petroleum-Beijing Beijing 102249 China

In the present paper, the interior non-uniformity of oscillating gas bubbles in liquids under an acoustic field is theoretically investigated, as well as the temperature non-uniformity in the surrounding liquid. The pressure, the density and the temperature inside the gas bubbles are quantitatively predicted for a wide range of bubble Mach numbers. It is shown that the bubble interior non-uniformity increases significantly with the increase of the bubble Mach number. In the case of a large Mach number, the values of aforementioned paramount parameters at the bubble center are significantly larger than those at the bubble interface. Except for a very thin layer close to the bubble interface, the effects of the temperature non-uniformity in the bulk liquid could be safely ignored.

关键词： Cavitation gas bubbles acoustic field radial oscillation non-uniformity Mach number

Determination and ecological risk assessment of arsenic and mercury in sediments from the Changjiang River Estuary and adjacent East China Sea

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Acta Oceanologica Sinica 2021年第4期40卷 32-38页

作者： yu'na zhang Qianwen Wang Central Laboratory Qingdao Agricultural UniversityQingdao 266109China

Arsenic(As)and mercury(Hg)are pollutants presented in marine environment.A process of atomic fluorescence spectrometry was proposed for the simultaneous determination of As and Hg in marine sediment samples(n=38)collected from the Changjiang River Estuary and adjacent East China *** proposed method used an optimized pretreatment procedure in an aqua regia–H_(2)O digestion *** of As and Hg increased to97%and 98%,respectively,with suitable precisions(2.7%–4.1%)under optimized process *** and Hg were widely presented in these samples,with the ranges of content values were 2.39–8.77μg/g for As and48.03–410.8 ng/g for *** indicate that anthropogenic factors strongly influence the abundances of As and Hg in investigated *** preliminary environmental risk assessment was investigated using the Igeoaccumulation index(Igeo)and anthropogenic contribution rate(M).Findings reveal that Hg demonstrates a strong ecological risk(with average values of 1.3 and 72%for Igeo and M,respectively)in the sediments from the Changjiang River Estuary and adjacent East China ***,Hg should be considered in future investigations.

关键词： arsenic mercury marine sediment spatial distributions ecological risk

Synthesis and Crystal Structure of the Complex [Zn(DBSHSH)(py)_2]

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Chinese Journal of Structural Chemistry 2006年第11期25卷 1347-1350页

作者： DING yu zhang Zhong-Hai yu Guo-Feng Department of Chemistry Xiaogan University Xiaogan Hubei 432000 China

The title complex, C24H18Br2N4ZnO3, has been prepared and characterized by X- ray diffraction analysis. It crystallizes in the triclinic system, space group PI^- with α = 0.89000（11）, b = 1.22172（14）, c= 1.31342（16）nm, a = 101.696（2）, β = 103.519（2）, γ = 110.744（2）°, V= 1.2329（3） nm^3, Z = 2, Mr = 635.61, F（000） = 628, Dc= 1.712 g/cm^3 and μ（MoKa） = 4.270 mm^-1. The structure was refined to the final R = 0.0524 and wR = 0.1239 for 2763 observed reflections with I 〉 2σ（ I）. The X-ray crystal structure analysis revealed that the center zinc（Ⅱ） is bonded with two oxygen and one nitrogen atoms from a tridentate ligand 3,5-dibromo-salicylaldehyde salicyloylhydrazone （DBSHSH） and two nitrogen atoms from two solvent pyridine molecules to form a distorted five-coordinate trigonal bipyramid. The intramolecular hydrogen bonds in the crystal structure play an important role in the title complex＇s thermostability.

关键词： 3,5-dibromo-salicylaldehyde salicyloylhydrazone [Zn(DBSHSH)(py)2] crystal structure