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Robust analysis of discounted Markov decision processes with uncertain transition probabilities

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Applied Mathematics(A Journal of Chinese Universities) 2020年第4期35卷 417-436页

作者： LOU Zhen-kai hou Fu-jun LOU Xu-ming School of Management and Economics Beijing Institute of TechnologyBeijing 100081China School of Economics and Management Xi’an University of Posts and TelecommunicationsXi’an 710121China

Optimal policies in Markov decision problems may be quite sensitive with regard to transition *** practice,some transition probabilities may be *** goals of the present study are to find the robust range for a certain optimal policy and to obtain value intervals of exact transition *** research yields powerful contributions for Markov decision processes(MDPs)with uncertain transition *** first propose a method for estimating unknown transition probabilities based on maximum *** the estimation may be far from accurate,and the highest expected total reward of the MDP may be sensitive to these transition probabilities,we analyze the robustness of an optimal policy and propose an approach for robust *** giving the definition of a robust optimal policy with uncertain transition probabilities represented as sets of numbers,we formulate a model to obtain the optimal ***,we define the value intervals of the exact transition probabilities and construct models to determine the lower and upper *** examples are given to show the practicability of our methods.

关键词： Markov decision processes uncertain transition probabilities robustness and sensitivity robust optimal policy value interval

Flume Experiment Investigation on Propagation Characteristics of Tidal Bore in A Curved Channel

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China Ocean Engineering 2023年第1期37卷 131-144页

作者： FAN jun TAO Ai-feng SHI mo-quan LI Ying PENG Ji Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing 210098China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China The Adminstrative Committee of Nantong Haimen Sanchang Industrial Park Nantong 226121China Zhejiang University of Water Resources and Electric Power Hangzhou 310018China China Renewable Energy Engineering Institute Beijing 100120China

Tidal bore is a special and intensive form of flow movement induced by tidal effect in estuary areas, which has complex characteristics of profile, propagation and flow velocity. Although it has been widely studied for the generation mechanism, propagation features and influencing factors, the curved channel will complicate the characteristics of tidal bore propagation, which need further investigation compared with straight channel. In this study, the flume experiments for both undular and breaking bores’ propagation in curved channel are performed to measure the freesurface elevation and flow velocity by ultrasonic sensors and ADV respectively. The propagation characteristics,including tidal bore height, cross-section surface gradient, tidal bore propagation celerity, and flow velocity are obtained for both sides of the curved channel. And three bore intensities are set for each type of tidal bores. The freesurface gradients are consistently enlarged in high-curvature section for undular and breaking bores, but have distinct behaviors in low-curvature section. The spatial distributions of tidal bore propagation celerity and flow velocity are compared between concave and convex banks. This work will provide experimental reference for engineering design of beach and seawall protection, erosion reduction and siltation promotion in estuary areas with the existence of tidal bores.

关键词： tidal bore curved channel flume experiment propagation celerity bore intensity

High-performance chromite by structure stabilization treatment

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Journal of Iron and Steel Research International 2020年第2期27卷 169-179页

作者： En-hui Wang Chang Luo jun-hong Chen Xin-mei hou Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Chromite is an important raw material applied in *** have been made to obtain high-performance chromite by adding MgO and Al203 from the viewpoint of structure *** order to explore the effect of Al203 and MgO on the structure,two formulas,i.e.,Mg-rich and Al-rich ones,were *** phase and microstructure development of samples heated in the temperature range of 1200-1600℃ were studied by X-ray diffraction and scanning electron microscopy with energy-dispersive *** and Al203 added have diffused into chromite successfully by heat *** diffuses into chromite,occupying the tetrahedral vacancies caused by the diffusion and oxidation of Fe2+ions to stabilize the ***203 diffuses into the surface layer of chromite,forming spinel-sesquioxide ***-rich sample which has spinel-sesquioxide structure shows better corrosion resistance toward fayalite slag than Mg-rich sample which has single spinel structure by blocking the interdiffusion between Fe^2+ions in fayalite slag and Mg^2+ions in chromite.

关键词： Chromite Structure optimization Corrosion resistance Refractory

THE STUDY ON A KIND OF CONTROL SYSTEM WITH NONLINEAR PARABOLIC DISTRIBUTED PARAMETERS

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Applied Mathematics and Mechanics(English Edition) 2002年第2期23卷 178-186页

作者： Zhou Jian-jun(周建军) XU Yan-hou(徐燕侯) State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei230026 P R China Department of Mechanic Engineering University of Science and Technology of China Hefei230026 P R China

The modelling of one kind of nonlinear parabolic distributed parameter control system with moving boundary, which had extensive applications was presented, Two methods were used to investigate the basic characteristics of the system: I) transforming the system it? the variable domain into that in the fixed domain; 2) transforming the distributed parameter system into the lumped parameter system. It is found that there are two critical values for the control variable : the larger one determines whether or not the boundary would move, while the smaller one determines whether or not the boundary, would atop automatically. For one-dimensional system of planar, cylindrical and spherical cases the definite solution problem can be expressed as a unified form. By means of the computer simulation the open-loop control system and close-cycle feedback control system have been investigated. Numerical results agree well with theoretical results. The computer simulation shows that the system is well posed, stable, measurable and controllable.

关键词： distributed parameter control system nonlinear moving boundary stability measurability controllability

Fast mode decision algorithm for spatial resolutions down-scaling transcoding to H.264

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第z1期7卷 70-75页

作者： BU Jia-jun mo Lin-jian CHEN Chun YANG Zhi School of Computer Science Zhejiang University Hangzhou 310027 China School of Computer Science Zhejiang University Hangzhou 310027 China School of Computer Science Zhejiang University Hangzhou 310027 China School of Computer Science Zhejiang University Hangzhou 310027 China

A fast mode decision algorithm is proposed in this paper to accelerate the process of transcoding videos into H.264with arbitrary rate spatial resolution down-scaling. The proposed algorithm consists of three steps. First, an early-stop technique is introduced to determine the 16× 16-mode blocks, which take up about 70% of all the macroblocks; then, a bottom-up merging process is performed to determine the mode of rest non-early-stopped blocks; and then, we adopt half-pixel motion estimation to further refine the acquired predictive motion vectors. In order to obtain the predictive motion vectors for early-stop and merging processes, we propose a motion vector composition scheme, which can reuse the information in the input pre-encoded videos to handle the spatial resolution down-scaling. Experimental results showed that our algorithm is about four times faster than the Cascaded-Decoder-Encoder method and has negligible PSNR drop and little bit rate increase.

关键词： Transcoding, H.264, mode decision, motion composition

Synthesis and blue light-emitting properties of 4,4'-bis(diphenylamino)-quinque(p-phenyl)s

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Chinese Chemical Letters 2007年第7期18卷 823-826页

作者： Zhong Hui Li mo jun Xiong Man Shing Wong Department of Chemistry Sichuan College of Education Chengdu 610041 China West China School of Pharmacy Sichuan University Chengdu 610041 China Department of Chemistry Hong Kong Baptist University Hong Kong China

An excellent organic blue light-emitting diode based on 4,4＇-bis（diphenylamino）-quinque（p-phenylene）s （OPP（5）-NPh） with a maximum luminance of up to 5000 cd/m^2 and a luminanous efficiency of 1.3 cd/A was reported. This diode was made by using a wide band-gap hole-blocking layer, F-TBB instead of PBD in the OLED devices. We attribute the good performance to the one trade-off involved in the use of F-TBB to obtain higher luminance is the increased turn-on voltages and slightly decreased device efficiencies.

关键词： 4,4'-Bis(diphenylamino)-quinque(p-phenylene)s Synthesis Organic light-emitting diode (OLED) Optical properties

The effect of dislocations on the thermodynamic properties of Ta single crystal under high pressure by molecular dynamics simulation

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Chinese Physics B 2018年第8期27卷 434-438页

作者： Yalin Li jun Cai Dan mo Yandong Wang School of Nuclear Science ＆ Engineering North China Electric Power University（NCEPU）Beijing 102206China State Key Laboratory for Advanced Metal Materials University of Science ＆ Technology BeijingBeijing 100083China

The thermodynamic properties of Ta metal under high pressure are studied by molecular dynamics simulation. For dislocation-free Ta crystal, all the thermodynamic properties considered are in good agreement with the results from exper- iments or higher level calculations. If dislocations are included in the Ta crystal, it is found that as the dislocation density increases, the hydrostatic pressure at the phase transition point of bcc-＋hcp and hcp--＋fcc decreases, while the Hugoniot temperature increases. Meanwhile, the impact pressure at the elastic-plastic transition point is found to depend on the crys- tallographic orientation of the pressure. As the dislocation density increases, the pressure of the elastic-plastic transition point decreases rapidly at the initial stage, then gradually decreases with the increase of the dislocation density.

关键词： Ta, high pressure phase transition dislocation density molecular dynamics (MD)

Deformylated Gramicidin A and Its Derivatives Showing High Antimicrobial Activity and Low Hemolytic Toxicity

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Chinese Journal of Chemistry 2019年第1期37卷 25-29页

作者： Wei-Wei Haoyang Min Zhang jun-Li hou Department of Chemistry Fudan University220 Handan RoadShanghai 200433China

Summary of main observation and conclusion Gramicidin A is a natural peptide,which shows high antimicrobial activity to Gram-positive bacteria. However,the hemolytic toxicity prevents its therapeutic *** demonstrated that by simply removing the formyl group at the N terminus,the hemolytic toxicity of the peptide could be obviously *** deformylated gramicidin A (1)could efficiently insert into the lipid bilayer to form transmembrane *** peptide can also selectively insert into the membrane of Gram-positive bacteria but not that of erythrocytes,leading to its high antimicrobial activity and very low hemolytic *** derivation of 1 could be achieved by decoration at the terminal NH2 group,which also produced peptides showing high activity and low hemolytic *** derivation method provided us with an efficient strategy to build a library for future activity and cytotoxicity screening in vitro and in vivo.

关键词： peptide build group

Neutral responses of plant community Ca concentration to nitrogen enrichment in a semiarid grassland

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Journal of Plant Ecology 2022年第2期15卷 286-293页

作者： Shuang-Li hou Xiao-Tao Lü jun-Jie Yang Erguna Forest-Steppe Ecotone Research Station CAS Key Laboratory of Forest Ecology and ManagementInstitute of Applied EcologyChinese Academy of SciencesShenyang 110016China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China

Calcium(Ca)is an essential nutrient for plant growth and Ca concentrations in forage have important implications for ruminant diet and *** remains an open question whether forage Ca concentration would be decreased by increasing nitrogen(N)*** manipulated the increasing rates of N addition(2008–2015)in a semiarid grassland,northern *** Ca concentrations for all species were examined in each plot under N *** Ca concentrations at functional group and community levels were calculated based on the concentration of each species presented and their relative biomass in each *** found that community-level Ca concentration remained stable across a gradient of wide-ranged N addition rates,although Ca concentration at both species and functional group levels showed negative responses to N *** that forbs had higher Ca concentration than grasses,the increasing relative biomass of forbs canceled out the negative responses of species-level and functional group-level Ca *** results further showed that community Ca pool showed a positive but saturating response to N addition,with a threshold at the rate of 10 g N m^(−2)yr^(−1).Our findings highlight the role of changes in plant relative biomass in controlling the responses of forage Ca concentration and stock to N enrichment.

关键词： calcium stock community composition ecological processes global changes nitrogen deposition temperate steppe