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Linear/branched Block Polyethylene Produced by a-Diimine Nickel(Ⅱ)Catalyst and Bis(phenoxy-imine)Zirconium Binary Catalyst System in the Presence of Diethyl Zinc

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Chinese Journal of Polymer Science 2021年第12期39卷 1581-1589页

作者： Ding-Ding Zhao Yan-Hui Hou Ke-Ning Zong mi-mi Cui Bin-Yuan Liu min Yang Hebei Key Laboratory of Functional Polymers Institute of Polymer Science and EngineeringHebei University of TechnologyTianjin 300130China State Key Laboratory of Separation Membranes and Membrane Processes School of Material Science and EngineeringTiangong UniversityTianjin 300160China

In order to promote development of linear/branched block polyethylenes based on new catalytic systems,we synthesized a novel *** nickel(Ⅱ)complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-Naryl *** activity of a-dimine nickl(Ⅱ)catalyst was 3.02x10^(6)g-mol_(ni)^(-1)·h^(-1) at 70℃,and resultant polyethylene possessed 135/1000C *** linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the a-dimine nicke(Ⅱ)complex/bis(phenoxy-imine)zirconium in the presence of diethyI *** the addition of ZnEtz(from 0 to 400),the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting *** molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained vla adjusting ZnEt;*** molar ratio of two *** addition,the branching degree of the polyethylene increased from 13/1000C to 56/1000 with the increase of the proportion of a dimine nickel(Ⅱ)*** this binary catalyst system,the reaction temperature of chain shutting polymerization can be carried out at 70℃,which is more conducive to industrial application.

关键词： Chain shuttling polymerization Linear/branched block polyethylene a-Diimine nickel Bis(phenoxy-imine)zirconium Ethylene

Martensitic transformation of Ti-18Nb(at.%) alloy with zirconium

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rare Metals 2012年第3期31卷 227-230页

作者： Ye, Wenjun mi, Xujun Song, Xiaoyun State Key Laboratory for Nonferrous Metals and Process General Research Institute for Nonferrous Metals Beijing 100088 China

The addition of 3%～9% Zr on the martensitic transformation of Ti-18Nb(at.%) alloy was investigated. The results of microstructure and X-ray diffraction (XrD) analysis show that the phase constitution of as-quenched Ti-18Nb-9Zr(at.%) alloy consists of the retained matrix and martensite, while that of the other three alloys is single martensite. No trace of athermal phase was found in any of the as-quenched alloys. Unlike the effect of Nb addition on the martensitic transformation start temperature Ms of Ti-18Nb(at.%) alloy, Ms de-creased nonlinearly as increasing the Zr addition from 3% to 9% and Ms decreased much more sharply as increasing the Zr addition. The Ms of as-quenched Ti-18Nb-9Zr alloy was around room temperature. The effect of Zr addition on the phase stabilizing in the Ti-18Nb(at.%) alloy was briefly discussed.

关键词： titanium alloy martensitic transformation alloying effect

Post-suburbanization in Qingpu New Town:Process and formation mechanism

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Journal of Geographical Sciences 2023年第7期33卷 1461-1481页

作者： WANG Shaobo LUO Xiaolong TANG mi Institute of County Economic Development Lanzhou UniversityLanzhou 730000China School of Architecture and Urban Planning Nanjing UniversityNanjing 210093China High-Quality Development Evaluation Institute Nanjing University of Posts and TelecommunicationsNanjing 210003China

Under the wave of globalization,some cities in China,especially the so-called “megacities” are entering or have already entered the stage of *** study places Shanghai suburbs in the post-suburbanization landscape and takes Qingpu New Town as an example to systematically analyze the development and formation mechanism of post-suburbanization *** study reveals the features of the post-suburbanization in China as ***,In China,post-suburbanization is achieved based on industrialization as well as on the promotion of *** urbanization has strengthened other functions of suburban spaces aside from living and production,the production attributes of suburbs remain ***,post-suburbanization space with the new town as the development model is an important path for a new round of suburban space growth,it has expanded the space for capital accumulation in metropolitan areas,thus promoting the possibility of reorganizing economic activities within metropolitan *** the same time,it focuses on the integration of industries and cities,and the simultaneous development of urbanization and *** turn,this promotes the accumulation of capital centered on the urban environment and manufacturing ***,China’s special institutional circumstance enables its government to organize various actors to form a growth alliance,which will act together in the production of post-suburbanization space.

关键词： post-suburbanization space production Qingpu New Town mechanism urban expansion

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HCloud:A Trusted JointCloud Serverless Platform for IoT Systems with Blockchain

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China Communications 2020年第9期17卷 1-10页

作者： Zheng Huang Zeyu mi Zhichao Hua Institute of Parallel and Distributed Systems Shanghai Jiao Tong UniversityShanghai 200240China

Cloud computing has been exploited in managing large-scale IoT *** cloud servers usually handle a large number of requests from various IoT *** to the fluctuant and heavy workload,the servers require the cloud to provide high scalability,stable performance,low price and necessary ***,traditional clouds usually offer computing service with the abstraction of virtual machine(VM),which can hardly meet these ***,different cloud vendors provide different performance stabilities and price models,which fluctuate according to the dynamic workload.A single cloud cannot satisfy all the requirements of the IoT scenario *** JointCloud computing model empowers the cooperation among multiple public ***,it is still difficult to dynamically schedule the workload on different clouds based on the VM *** paper introduces HCloud,a trusted JointCloud platform for IoT systems using serverless computing *** allows an IoT server to be implemented with multiple serverless functions and schedules these functions on different clouds based on a schedule *** policy is specified by the client and includes the required functionalities,execution resources,latency,price and so *** collects the status of each cloud and dispatches serverless functions to the most suitable cloud based on the schedule *** leveraging the blockchain technology,we further enforce that our system can neither fake the cloud status nor wrongly dispatch the target *** have implemented a prototype of HCloud and evaluated it by simulating multiple cloud *** evaluation results show that HCloud can greatly improve the performance of serverless workloads with negligible costs.

关键词： IoT blockchain serverless jointcloud

Factors Influencing Proppant Transportation and Hydraulic Fracture Conductivity in Deep Coal Methane reservoirs

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Fluid Dynamics & Materials Processing 2024年第11期20卷 2637-2656页

作者： Fan Yang Honggang mi China United Coal Bed Methane Ltd. Beijing100124China Provincial Center of Technology Innovation for Coal Measure Gas Co-Production Taiyuan030032China

The gas production of deep coalbed methane wells in Linxing-Shenfu block decreases rapidly,the water output is high,the supporting effect is poor,the effective supporting fracture size is limited,and the migration mechanism of proppant in deep coal reservoir is not clear at *** investigate the migration behavior of proppants in complex fractures during the volume reconstruction of deep coal and rock reservoirs,an optimization test on the conductivity of low-density proppants and simulations of proppant migration in complex fractures of deep coal reservoirs were *** study systematically analyzed the impact of various fracture geometries,proppant types and fracturingfluid viscosities on proppant ***,the study compared the outcomes of dynamic proppant transport experiments with simulation *** results show that the numerical simulation is consistent with the results of the proppant dynamic sand-carrying *** the conditions of low viscosity and large pumping-rate,a high ratio of 40/70 mesh proppant can facilitate the movement of the proppant to the depths of fractures at all *** technical goal is to create comprehensive fracture support within intricate trapezoidal fractures in deep coal and rock reservoirs without inducing sand *** sand ratio is controlled at 15%–20%,with a proppant combination ratio of 40/70:30/50:20/40=6:3:*** pumping operations can effectively address the issue of poor support in complex fractures in deep coal *** research results have been successfully applied to the development of deep coalbed methane in the Linxing-Shenfu block,Ordos Basin.

关键词： Deep coal fracture reticular fracture proppant density fracture conductivity proppant transportation

How can inter-specific interferences explain coexistence or confirm the competitive exclusion principle in a chemos tat?

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International Journal of Biomathematics 2018年第8期11卷 307-326页

作者： mi led El Hajji ENIT-LAMSIN BP. 37 1002 Tunis-Belvedere Tunis El Manar University Tunis Tunisia General Studies Department College of Telecom and Electronics Technical and Vocational Training Corporation Jeddah 2146 Saudi Arabia

In this paper, I consider two species feeding on limiting substrate in a chemostat taking into account some possible effects of each species on the other one. System of differential equations is proposed as model of these effects with general inter-specific density-dependent growth rates. Three cases were considered. The first one for a mutual inhibitory relationship where it is proved that at most one species can survive which confirms the competitive exclusion principle. Initial concentrations of species have great importance in determination of which species is the winner. The second one for a food web relationship where it is proved that under general assumptions on the dilution rate, both species persist for any initial conditions. Finally, a third case dealing with an obligate mutualistic relationship was discussed. It is proved that initial condition has a great importance in determination of persistence or extinction of both species.

关键词： Chemostat mutual-inhibition food web obligate mutualism asymptotic behavior coexistence competitive exclusion principle dulac criterion thieme's result

A nonlinear dynamic macro-element for demand assessment of bridge substructures subjected to ship collision

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第11期12卷 826-836页

作者： Wei FAN Wan-cheng YUAN mi ZHOU IState Key Laboratory of Disaster reduction in Civil Engineering Tongji University Shanghai 200092 China 2Department of Civil Engineering Purdue University West Lafayette 47907 USA Key Laboratory for Old Bridge Detection and reinforcement Technology of ministry of Transportation Chang＇an University Xi ＇an 710064 China

For the dynamic demand assessment of bridge structures under ship impact loading,it may be prudent to adopt analytical models which permit rapid analysis with reasonable ***,a nonlinear dynamic macro-element is proposed and implemented to quantify the demand of bridge substructures subjected to ship *** the proposed nonlinear macro-element,a combination of an elastic-plastic spring and a dashpot in parallel is employed to describe the mechanical behavior of ship-bows with strain rate *** on the analytical model using the proposed macro-element,a typical substructure under 5000 deadweight tonnage(DWT) ship collision is *** analyses indicate that the responses of the structure using the nonlinear macro-element agree with the results from the high resolution model,but the efficiency and feasibility of the proposed method increase significantly in practical ***,comparisons between some current design codes(AASHTO,JTGD60-2004,and TB10002.1-2005) and the developed dynamic analysis method suggest that these design codes may be improved,at least to consider the effect of dynamic amplification on structural demand.

关键词： Nonlinear macro-element Ship-bridge collision P-a curve Dynamic demand Design codes

Assessment of nutrient distributions in Lake Champlain using satellite remote sensing

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Journal of Environmental Sciences 2014年第9期26卷 1831-1836页

作者： Elizabeth M.Isenstein mi-Hyun Park Department of Civil and Environmental Engineering University of Massachusetts AmherstMA01003USA

The introduction of nutrients to lakes causing eutrophic conditions is a major problem around the world. Proper monitoring and modeling are important to effectively manage eutrophication in lake waters. The goal is to develop remote sensing models for nutrients, total phosphorus and total nitrogen, in Lake Champlain. The remote sensing models were created using multivariate linear regression with the unique band combinations of Landsat Enhanced Thematic Mapper Plus （ETM＋） imagery based on the empirical relationship with the field observations. The resulting models successfully showed nutrient distributions in the most eutrophic part of Lake Champlain, missisquoi Bay, with reasonable adjusted coefficient of determination values （r2 = 0.81 and 0.75 for total phosphorus and total nitrogen, respectively）. The results show the feasibility and the utility of satellite imagery to detect spatial distributions of lake water quality constituents, which can be used to better understand nutrient distributions in Lake Champlain. This approach can be applicable to other lakes experiencing eutrophication assisting decision making when implementing Best Management Practices and other mitigation techniques to lakes.

关键词： remote sensingMonitoringNutrientsPhosphorus

Calculations of dynamic multipolar polarizabilities of the Cd clock transition levels

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Chinese Physics B 2021年第8期30卷 295-300页

作者： mi Zhou Li-Yan Tang State Key Laboratory of Magnetic resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

The pursuit of a systematic frequency uncertainty beyond 10^(-18) clock has triggered a multitude of investigations on the multipolar and higher-order lattice light *** Cd atom has been proposed as a new candidate for the development of a lattice clock because of its smaller blackbody radiation shift at room ***,we apply an improved combined method of the Dirac-Fock plus core polarization and relativistic configuration interaction methods to calculate the dynamic multipolar polarizabilities of the Cd clock *** effects of the high-order core-polarization potentials on the energies,reduced matrix elements,and multipolar polarizabilities have been evaluated *** detailed comparison with available literature demonstrates that taking into account of the high-order core-polarization potentials is a simple and effective approach to improve the results of atomic properties for heavy atoms.

关键词： Cd atomic clock multipolar polarizabilities high-order core-polarization potentials DFCP+rCI method