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Application of rare earths in fluid catalytic cracking： A review

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Journal of Rare Earths 2017年第10期35卷 941-956页

作者： aaron Akah Research and Development Center Saudi Aramco Dhahran 31311 Saudi Arabia

The need for more active and hydrothermally stable fluid catalytic cracking（FCC）catalysts to combat the effect of metal contaminants has led to an increase in demand for rare earth *** earth oxides enhance catalyst activity and prevent the loss of acid sites during the FCC unit operation,especially when heavy residue with high metal content is used as *** this paper,a review was carried out to show the effects of rare earth elements on the structure,activity,and stability of FCC ***,the use of rare earth elements as vanadium traps was analyzed in conjunction with the mechanism of catalyst deactivation by *** objective was to elucidate the interaction of vanadium species with the zeolite component of the FCC catalysts and the role of rare earth elements in countering the deleterious effects of vanadium on the FCC catalysts.

关键词： FCC catalyst rare earth vanadium trap zeolites

Closed-loop drip irrigation control using a hybrid wireless sensor and actuator network

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Science China(Information Sciences) 2011年第3期54卷 577-588页

作者： FRANZEN aaron Department of Biosystems and Agricultural Engineering Oklahoma State University

In this research, a closed-loop drip irrigation control hybrid wireless sensor and actuator network (HWSAN) prototype were developed and deployed in a crop field for soil property precise measurement and precision irrigation in accordance with the measured soil property. The HWSAN was composed of a wireless sensor and actuator network (WSAN) used for in-field soil property monitoring and irrigation control and a laboratory supervising system. The WSAN included ten sensor nodes, five irrigation control nodes, a central node, a gateway and a cellular modem. The laboratory supervising system was formed by a web-server. The system could automatically sample soil properties including soil moisture, electrical conductivity, and nearsurface temperature at four different depths underground and transmit field data through cellular network to the web-server. Closed-loop control was achieved through the control nodes listening uploading packets from its paired sensor nodes to control drip irrigation. Results from the quality of service (QoS) evaluation included: the data packet transmission rate was 84.76%, data accuracy rate was greater than 97% and no in-field data transmission errors.

关键词： wireless sensor network drip irrigation soil property monitoring precision agriculture

The kinetics of static recovery by dislocation climb

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npj Computational Materials 2022年第1期8卷 973-982页

作者： aaron A.Kohnert Laurent Capolungo Materials Science and Technology Division Los Alamos National LaboratoryLos AlamosNMUSA

The initial microstructure of a wide range of structural materials is conditioned by thermo-mechanical treatments such as hot-working,tempering,or solution *** the elevated temperatures associated with these treatments the dislocation microstructure evolves,usually decreasing in density through a process known as static *** its technological relevance,static recovery is not fully characterized from a theoretical standpoint,with even the controlling mechanisms subject to *** this study,a climb-enabled discrete dislocation dynamics(DDD)capability is leveraged to explore the kinetics of static recovery in pure Fe when controlled by dislocation *** data from these simulations is used to develop a revised static recovery law,and provides the parameters appropriate for predictive microstructure models in *** law differs from previous analytical derivations invoking climb of dislocations,following the logarithmic trends typical of experimental observations where prior work did *** comparison between the recovery law derived from DDD to experimental recovery data in alpha Fe shows strong agreement across a range of temperatures,and suggests that climb is the controlling mechanism for static recovery in pure metals.

关键词： dislocation law treatment

A Grid-friendly Neighborhood Energy Trading Mechanism

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Journal of Modern Power Systems and Clean Energy 2022年第5期10卷 1349-1357页

作者： Anula Abeygunawardana aaron Liu Gerard Ledwich Queensl and University of Technology BrisbaneAustralia IEEE

More customers are tending to install batteries with photovoltaic(PV), so they can better control their electricity bills. In this context, customers may be tempted to go offgrid at a substantial up-front cost, leading electricity companies into a death spiral, thereby raising electricity price further on those remaining on grid. Neighborhood energy markets can promote the sharing of locally generated renewable energy and encourage prosumers to stay on grid with financial incentives. A novel neighborhood energy trading(NET) mechanism is developed using the topology of existing radial distribution network to encourage sustainable energy sharing in neighborhood and encourage prosumers to stay on grid. This mechanism considers loss, congestion management, and voltage regulation, and it is scalable with low computation and communication *** IEEE test system is used to validate the NET *** simulation shows that the price and flow results are obtained with fast computation speed(within 10 iterations) and with loss reflected, flow limit reinforced, and voltage *** study proves that the economic demand-supply-based pricing mechanism can be applied effectively in distribution networks to help encourage more renewable energy sharing in sustainable neighborhood and avoid energy network death spiral.

关键词： Direct power flow directional adjacency local energy market peer-to-peer prosumer solar community sustainable building transdisciplinary research

A causation mechanism for coal bursts during roadway development based on the major horizontal stress in coal:Very specific structural geology causing a localised loss of effective coal confinement and Newton’s second law

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International Journal of Mining Science and Technology 2020年第1期30卷 39-47页

作者： Russell Frith Guy Reed aaron Jones Mine Advice Pty Ltd BeresfieldNew South Wales 2322Australia

In 2017,one of the international authorities on coal bursts,Mark Christopher,published a paper entitled"Coal bursts that occur during development:A rock mechanics enigma",in which several relevant technical issues were *** paper outlines what is considered to be a credible,first-principles,mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of"constraint"to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ,albeit on a statistically very rare *** basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales,Australia,in 2014 and from the Sunnyside District in Utah,the United ***"cause and effect"model for development of coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events,being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst *** model could also form the basis for a robust,riskbased approach utilising a"hierarchy of controls",to the operational management of the development coal burst ***,the use of pre-mining predictions for likely burst-prone and non-burstprone areas,the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate,and finally the development of an operational Trigger Action Response Plan(TARP)that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place.

关键词： Development coal burst Wing-cracks Austar Mine Sunnyside Mine Major horizontal stress in coal

Global optimal path planning for mobile robot based onimproved Dijkstra algorithm and ant system algorithm

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Journal of Central South University of Technology 2006年第1期13卷 80-86页

作者：谭冠政贺欢 aaron Sloman School of Information Science and Engineering Central South University Changsha 410083 China School of Computer Science The University of Birmingham Birmingham B15 2TT UK School of Information Science and Engineering Central South University Changsha 410083 China School of Computer Science The University of Birmingham Birmingham B15 2TT UK

A novel method of global optimal path planning for mobile robot was proposed based on the improved Dijkstra algorithm and ant system algorithm. This method includes three steps: the first step is adopting the MAKLINK graph theory to establish the free space model of the mobile robot, the second step is adopting the improved Dijkstra algorithm to find out a sub-optimal collision-free path, and the third step is using the ant system algorithm to adjust and optimize the location of the sub-optimal path so as to generate the global optimal path for the mobile robot. The computer simulation experiment was carried out and the results show that this method is correct and effective. The comparison of the results confirms that the proposed method is better than the hybrid genetic algorithm in the global optimal path planning.

关键词： mobile robot global optimal path planning improved Dijkstra algorithm ant system algorithm MAKLINK graph free MAKLINK line

Trends in forensic DNA database:transnational exchange of DNA data

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Forensic Sciences Research 2020年第1期5卷 8-14页

作者： aaron Opoku Amankwaa Science and Justice Research Interest Group School of LawNorthumbria UniversityNewcastle Upon TyneUK

The transnational exchange of forensic DNA data has become a modern trend in fighting cross-border crime,terrorism and illegal *** DNA data allow the police to identify,eliminate or link individuals associated with a ***,different crime scenes can be linked via the DNA profile to identify serial offenders or determine crime *** to the transnational exchange of DNA data can be categorized into four:(1)creation of an international DNA database,(2)linked or networked national DNA data-bases,(3)request-based exchange of data,and(4)a combination of *** countries operate the combination system of data *** paper briefly introduces the different approaches in the transnational sharing of forensic DNA data,the legislative and operational framework,pattern of data exchange and participating states,and policy challenges associ-ated with data ***,most DNA exchange systems are modelled as the European Union Prüm *** operates under two stages:hit/no-hit query and further information *** scope of the data exchange is governed by individual national legislation that determines the type of information that can be shared and the national authority responsible for the *** DNA data exchange has been instrumental in resolving serious crimes such as gang and serial rape,and armed robbery,adequate infor-mation about their overall effectiveness and efficiency is ***,operational,legal and ethical challenges including issues of privacy and proportionality appear to limit the full potential of the DNA data exchange system.

关键词： Forensic DNA exchange Prüm forensic DNA legislation genetic privacy proportionality social security

Effects of contaminant metal ions on precipitation recovery of rare earth elements using oxalic acid

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Journal of Rare Earths 2022年第3期40卷 482-490,I0005页

作者： Wencai Zhang aaron Noble Bin Ji Qi Li Department of Mining and Minerals Engineering Virginia Polytechnic Institute and State UniversityBlacksburgVA24061USA

Solution equilibrium calculations were performed in this study to understand the impact of contaminant metal ions on the precipitation efficiency of selected rare earth elements(Ce^(3+),Nd^(3+),and Y^(3+))using oxalic acid as a *** metal ions,Al^(3+) and Fe^(3+),are found to considerably affect the precipitation efficiency of *** Al^(3+) and Fe^(3+)concentrations are increased by 1×10^(−4) mol/L,in order to achieve an acceptable cerium recovery of 93%from solutions containing 1×10^(−4) mol/L Ce^(3+),oxalate dosage needs to increase by 1.2×10^(−4) and 1.68×10^(−4) mol/L,*** great impacts on the required oxalate dosage are also observed for Nd^(3+) and Y^(3+),which indicates that oxalic acid consumption and cost will be largely increased when the trivalent metal ions exist in REE-concentrated *** of the divalent metal ions on the oxalate dosage are ***,solution equilibrium calculation results show that the precipitation of Fe^(3+) and Ca^(2+)(e.g.,hematite and Ca(C_(2)O_(4))∙H_(2)O(s))likely occurs during the oxalate precipitation of REEs at relatively high pH(e.g.,pH 2.5),which will reduce rare earth oxalate product *** addition to the metal ions,anionic species,especially SO_(4)^(2-),are also found to negatively affect the precipitation recovery of *** example,when 0.1 mol/L SO_(4)^(2-) occurs in a solution containing 1×10^(−4) mol/L Ce^(3+) and 4×10^(−4) mol/L oxalate,the pH needs to be elevated from 2.0 to 3.3 to achieve the acceptable ***,findings from this study provide guidance for the obtainment of high-purity rare earth products from solutions containing a considerable amount of contaminant metal ions by means of oxalic acid precipitation.

关键词： Rare earth elements Oxalic acid Precipitation Contaminant metal ions

Frequency dispersion effect and parameters extraction method for novel HfO2 as gate dielectric

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Science China(Information Sciences) 2010年第4期53卷 878-884页

作者： ZHAO aaron TALLAVARJULA Sai Applied Materials Inc Sunnyvale CA 94086USA

The electric characteristic of MOS capacitor with HfO2/SiO2/p-Si grown by ALCVD （atom layer chemical vapor deposition） is investigated. The C-V curves show that the accumulation capacitances take on the frequency dispersion at high frequency. For MOS capacitor with ultra thin HfO2/SiO2gate stack, different fabrication processes and measurement equipment will cause parasitic effect. Here an equivalent circuit model that can eliminate the frequency dispersion effect is proposed. The C-V characteristics curve at high frequency shows some distortion because of the bulk defects and the interface states. This paper discusses the distortion of the high frequency MOS C-V characteristic curve. A data processing method is advanced and interface trap density distribution in the band gap is presented. By comparing the ideal C-V curve with the experimental C-V curve, the typical electrical parameters of MOS capacitor are extracted, including the shift of flat-band voltage, the oxide charges and the density of interface traps at the SiO2/Si interface.

关键词： high k gate dielectric HfO2 frequency dispersion equivalent circuit model two-frequency C-V measurement parameters extraction