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An Empirical Model of Tropical Cyclone Intensity Forecast in the Western North Pacific

Journal of Meteorological Research 2022年第5期36卷 691-702页

作者： chen ma Tim LI Jiangsu Meteorological Observatory Jiangsu Meteorological BureauNanjing 210019China Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)NanjingUniversityof Information Science&TechnologyNanjing210044China International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and TechnologyUniversityofHawaiiHI96822USA Key Laboratory of Transportation Meteorology China Meteorological AdministrationNanjing 210019China

The relative impact of environmental parameters on tropical cyclone(TC) intensification rate(IR) was investigated through a box difference index(BDI) method, using TC best track data from Joint Typhoon Warning Center and environmental fields from the NCEP final analysis data over the western North Pacific(WNP) during 2000–*** are total 6307 TC samples with a 6-h interval, of which about 14% belong to rapid intensification(RI) category. The analysis shows that RI occurs more frequently with higher environmental sea surface temperature, higher oceanic heat content, and lower upper-tropospheric temperature. A moderate easterly shear is more favorable for TC intensification. TC intensification happens mostly equatorward of 20°N while TC weakening happens mostly when TCs are located in the northwest of the basin. Mid-tropospheric relative humidity and vertical velocity are good indicators separating the intensification and non-intensification groups. A statistical model for TC intensity prediction was constructed based on six environmental predictors, with or without initial TC intensity. Both models are skillful based on Brier skill score(BSS) relative to climatology and in comparison with other statistical models, for both a training period(2000–2018) and an independent forecast period(2019–2020).

关键词： tropical cyclone rapid intensification prediction model

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Subspace-based identification of discrete time-delay system

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Frontiers of Information Technology & Electronic Engineering 2016年第6期17卷 566-575页

作者： Qiang LIU Jia-chen ma School of Astronautics Harbin Institute of Technology School of Information and Electrical Engineering Harbin Institute of Technology

We investigate the identification problems of a class of linear stochastic time-delay systems with unknown delayed states in this study. A time-delay system is expressed as a delay differential equation with a single delay in the state vector. We first derive an equivalent linear time-invariant(LTI) system for the time-delay system using a state augmentation technique. Then a conventional subspace identification method is used to estimate augmented system matrices and Kalman state sequences up to a similarity transformation. To obtain a state-space model for the time-delay system, an alternate convex search(ACS) algorithm is presented to find a similarity transformation that takes the identified augmented system back to a form so that the time-delay system can be recovered. Finally, we reconstruct the Kalman state sequences based on the similarity transformation. The time-delay system matrices under the same state-space basis can be recovered from the Kalman state sequences and input-output data by solving two least squares problems. Numerical examples are to show the effectiveness of the proposed method.

关键词： Identification problems Time-delay systems Subspace identification method Alternate convex search Least squares

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Characterization and application of a recombinant dopa decarboxylase from Harmonia axyridis for the efficient biosynthesis of dopamine

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Chinese Journal of Chemical Engineering 2022年第1期35卷 449-456页

作者： Siyuan Gao Yuanke Guo chen ma Ding ma Kequan chen Pingkai Ouyang Xin Wang State Key Laboratory of materials-Oriented Chemical Engineering College of Biotechnology and Pharmaceutical EngineeringNanjing Tech UniversityNanjing 211816China

Here,a dopa decarboxylase(DDC)from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of *** the production of recombinant DDC,the cultivation conditions including IPTG concentration,temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg^(-1) crude *** the purification of DDC with a recovery yield of 68.79%,its activity was further *** Vmax,Km,Kcat,and Kcat/Km of DDC for d ihyd roxy pheny la la nine(dopa)were 0.02 mmol·ml^(-1)·s^(-1),2.328 mmol·ml^(-1),10435.90 s^(-1) and4482.77 ml,mmol *** highest DDC activity was observed at the condition of pH 7.5 and 45℃.With the purified DDC,the feasibility to produce dopamine from L-dopa was *** optimal yield was determined at the following bioconversion conditions:pH of 7,0,the reaction temperature of 40℃,0.4 mmol·L^(-1) of PLP and 4 g·L^(-1) of L-dopa,Subsequently,a fed-batch process for the production of dopamine was developed and the effect of oxygen was *** titer,yield and productivity of dopamine reached up to 21.99 g·L^(-1)80.88%and 14.66 g·L^(-1)·h^(-1) at 90 min under anaerobic condition.

关键词： Dopa decarboxylase Dopamine Enzyme catalysis Fed-batch bioconversion

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Retrieving the surface axis of the Kuroshio off southern coast of Japan from SST data

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Acta Oceanologica Sinica 2007年第1期26卷 1-11页

作者： SHAO Quanqin chen Zhuoqi ma Weiwei Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

One thousand and forty-nine sea surface isotherm maps during 1990 - 2000 were used to detect the Kuroshio axis off the coast of Japan. The current axis on the surface cannot be identified by just one indicative isotherm as is commonly done in deep water, but still there are complicated isotherms indicatives of the Kuroshio axis. Three types of isotherms indicatives of the surface axis of the Kuroshio are identified, which are nesti indicator, warm-tongue-isotherm-indicator, and isotherm-indicator. The ocourrence frequency of NWTI-type is 72%, that of WTII-type is 19.1% and that of Ⅱ-type is 8.9%. The vector-based and raster-based methods were introduced and used to retrieve automatically the Kumshio paths from SST data. The total retrieving percentage is 74% by the three methods, 52.3% by the vector method, 56.8% by one raster method and 49.6% by another raster method. For the NWTI - type, the total retrieving percentage is 91.3% by the three methods, 64.4% by the vector method, 75. 9% by one raster method and 65% by another raster method. Using retrieving results of the Kumshio axis from SST data,the Kuroshio path detour is analyzed during 1990 - 2000.

关键词： Kuroshio axis SST nesting-warm-tongue-indicator warm-tongue-isotherm-indicator isotherm-indicator GIS

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Fabrication of AlN-TiC/Al composites by gas injection processing

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Rare Metals 2006年第6期25卷 659-664页

作者： YU Huashun chen Hongmei ma Rendian MIN Guanghui The Key Laboratory of Liquid Structure and Heredity of materials Ministry of Education Shandong University Jinan 250061 China

The fabrication of AlN-TiC/Al composites by carbon- and nitrogen-containing gas injection into Al-Mg-Ti melts was studied. It was shown that AlN and TiC particles could be formed by the in situ reaction of mixture gas （N2 ＋ C2H2 ＋ NH3） with Al-Mg-Ti melts. The condition for the formation of AlN was that the treatment temperature must be higher than 1373 K, and the amounts of AlN and TiC increased with the increase of the treatment temperature and the gas injection time It was considered that AlN was formed by the direct reaction of Al with nitrogen-containing gas at the interface of the gas bubble and the melt. However, the mechanism of TiC formation is a combination mechanism of solution-precipitation and solid-liquid reaction.

关键词： in situ composites gas injection aluminum nitride titanium carbide

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Conflict detection and resolution for authorization policies in workflow systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第8期10卷 1082-1092页

作者： chen-hua ma Guo-dong LU Jiong QIU Engineering & Computer Graphics Institute Zhejiang University Hangzhou 310027 China Department of Computer Engineering Hangzhou Dianzi University Hangzhou 310008 China

The specification of authorization policies in access control models proposed so far cannot satisfy the requirements in workflow management systems(WFMSs).Furthermore,existing approaches have not provided effective conflict detection and resolution methods to maintain the consistency of authorization polices in *** address these concerns,we propose the definition of authorization policies in which context constraints are considered and the complicated requirements in WFMSs can be *** on the definition,we put forward static and dynamic conflict detection methods for authorization *** defining two new concepts,the precedence establishment rule and the conflict resolution policy,we provide a flexible approach to resolving conflicts.

关键词： Workflow management system (WFMS) Authorization policy Conflict detection and resolution

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A Scheme for Teleportation of an Unknown Entangled Coherent State via Raman Interaction

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Communications in Theoretical Physics 2007年第2期47卷 330-332页

作者： chen Mei-Feng ma Song-She Department of Electronic Science and Applied Physics Fuzhou University Fuzhou 350002 China

A scheme is reported for the teleportation of entangled coherent states through the degenerate Raman interaction. The scheme uses an entangled state of an atom and two coherent states as a quantum channel. It makes lu... 详细信息

关键词： Raman interaction teleportation entangled coherent state

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Responses of soil Collembolans to vegetation restoration in temperate coniferous and broad-leaved mixed forests

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Journal of Forestry Research 2020年第6期31卷 2333-2345页

作者： chen ma Xiuqin Yin Huan Xu Yan Tao School of Geographical Sciences Northeast Normal University5268 Renmin StreetChangchun 130024Jilin ProvincePeople’s Republic of China Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization 5268 Renmin StreetChangchun 130024Jilin ProvincePeople’s Republic of China Key Laboratory of Vegetation Ecology Ministry of EducationNortheast Normal UniversityChangchun 130024Jilin ProvincePeople’s Republic of China

A total of 900 soil samples were collected from five habitats,including primary coniferous broad-leaved mixed forests,secondary coniferous broad-leaved mixed forests,secondary broad-leaved forests,secondary shrub forests,and cutover lands in spring,summer,and autumn to quantify responses of soil Collembolans(springtails)to the restoration of vegetation of temperate coniferous and broad-leaved mixed *** results reveal that the taxonomic composition of Collembolans varied in the different stages of vegetation *** variations were in regard to their abundance and *** similarities existed in Collembola communities at different stages of vegetation restoration,and distribution patterns of Collembola taxa displayed an evenness throughout all *** Collembolans tended to gather on litter layers and soil surface;the highest abundance was found in the upper 5 cm soil layer during the initial stages of vegetation ***,Proisotoma,and Folsomia genera responded positively to the restoration of ***,responses of Ceratophysella and Parisotoma genera were *** addition,the Onychiuridae family did not respond to the vegetation restoration *** was concluded that restoration of vegetative cover can increase the abundance of soil Collembolans,but different genera respond differently.

关键词： Soil Collembolans(springtails) Temperate coniferous and broad-leaved mixed forests Vegetation restoration

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Suspended penetration wetting state of droplets on microstructured surfaces

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Science China(Physics,Mechanics & Astronomy) 2021年第4期64卷 81-89页

作者： Jing Lou SongLin Shi chen ma CunJing Lv QuanShui Zheng Department of Engineering Mechanics and Center for Nano and Micro Mechanics Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

When a water droplet on a micropillar-structured hydrophobic surface is submitted to gradually increased pressure, the CassieBaxter wetting state transforms into the Wenzel wetting state once the pressure exceeds a critical value. It has been assumed that the reverse transition(Wenzel-to-Cassie-Baxter wetting state) cannot happen spontaneously after the pressure has been *** this paper, we report a new wetting-state transition. When external pressure is exerted on a droplet in the Cassie-Baxter wetting state on textured surfaces with high micropillars to trigger the breakdown of this wetting state, the droplet penetrates the micropillars but does not touch the base of the surface to trigger the occurrence of the Wenzel wetting state. We have named this state the suspended penetration wetting state. Spontaneous recovery from the suspended penetration wetting state to the initial Cassie-Baxter wetting state is achieved when the pressure is removed. Based on the experimental results, we built models to establish the penetration depth that the suspended penetration wetting state could achieve and to understand the energy barrier that influences the equilibrium position of the liquid surface. These results deepen our understanding of wetting states on rough surfaces subjected to external disturbances and shed new light on the design of superhydrophobic materials with a robust wetting stability.

关键词： wetting micropillars hydrophobic transition stability

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Three-component Reaction of Aromatic Aldehyde,malononitrile and Aliphatic Amine Leading to Different Pyridine Derivatives

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Chemical Research in Chinese Universities 2010年第6期26卷 937-941页

作者： chen Jiao ma Zhen YAN Chao-guo College of Chemistry ＆ Chemical Engineering Yangzhou University Yangzhou 225002 P. R. China

The three-component reaction of aromatic aldehyde,malononitrile and aliphatic amine in a mixed solvent of methanol and water exhibited very interesting molecular diversity and gave the derivatives of polysubstituted N-methyldihydropyridines,2-dialkylaminopyridines and 2-methoxypyridines as main products according to the structure of aliphatic amines used.

关键词： Multicomponent reaction malononitrile Aldehyde Dihydropyridine Pyridine Aminopyridine

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