Planning and Decision-making for Connected Autonomous Vehicles at Road Intersections:A Review

Planning and decision-making technology at intersections is a comprehensive research problem in intelligent transportation systems due to the uncertainties caused by a variety of traffic participants.As wireless communication advances,vehicle infrastructure integrated algorithms designed for intersection planning and decision-making have received increasing attention.In this paper,the recent studies on the planning and decision-making technologies at intersections are primarily overviewed.The general planning and decision-making approaches are presented,which include graph-based approach,prediction base approach,optimization-based approach and machine learning based approach.Since connected autonomous vehicles(CAVs)is the future direction for the automated driving area,we summarized the evolving planning and decision-making methods based on vehicle infrastructure cooperative technologies.Both four-way signalized and unsignalized intersection(s)are investigated under purely automated driving traffic and mixed traffic.The study benefit from current strategies,protocols,and simulation tools to help researchers identify the presented approaches’challenges and determine the research gaps,and several remaining possible research problems that need to be solved in the future.

Synthesis,phase transformation and applications of CeCO_(3)OH:A review

CeCO_(3)OH has a unique crystal structure and excellent optical,electronic and catalytic properties,which has been widely investigated for many applications.Interestingly,ceria obtained from CeCO_(3)OH has a morphology that is similar to that of the precursor,and the CeO_(2)-based products obtained from CeCO_(3)OH exhibit outstanding properties,such as catalytic performances,owing to their designed morphology and oxygen vacancies(OVs).To introduce CeCO_(3)OH into a wider range of potential researchers,we first systematically review the physico-chemical properties,synthesis,reaction and morphology tuning mechanism of CeCO_(3)OH,and summarize the conversion behavior from CeCO_(3)OH to ceria.Then,we thoroughly survey the applications of CeCO_(3)OH and its conversion products.Suggestions for further investigations of CeCO_(3)OH are also made in this review.It is hoped that the exhaustive co mpilation of the valuable properties and considerable potential investigations of CeCO_(3)OH will promote further applications of CeCO_(3)OH and CeO_(2)-based functional materials.

Cerium oxide inclusion nucleation mechanism based on classical nucleation theory and two-step nucleation

It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions according to classical nucleation theory and a two-step nucleation mechanism.The nucleation rates and nucleation radii of these inclusions are obtained,and the results demonstrate a considerable difference between theoretical and experimental values.On the basis of a two-step nucleation mechanism,(CeO_(2))_(n) and(Ce_(2)O_(3))_(n)(n=1-6)clusters were constructed and the thermodynamic properties of both these clusters and of cerium oxide nanoparticles were analyzed.In addition,the entropies and heat capacity changes of cerium oxides were determined using first principles calculations and are found to be consistent with literature data.The present data indicate that the cerium oxide inclusion nucleation pathway can be summarized as[Ce]+[O]→(CeO_(2))n/(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(2)→core(Ce_(2)O_(3)crystal)-shell((Ce_(2)O_(3))_(2) cluster)nanoparticles→(Ce_(2)O_(3))bulk.

高硫高硅铝土矿焙烧–溶出性能研究

采用悬浮焙烧对高硫高硅铝土矿进行处理,考察了不同焙烧温度对矿石中硫含量的影响,通过X射线衍射和扫描电子显微镜分析了不同温度条件下焙烧对铝土矿中物相变化及微观形貌的影响,研究了焙烧温度对矿石中氧化铝溶出性能的影响。结果表明,悬浮焙烧温度600℃及以上时,能够使铝土矿硫化型硫含量降至0.2wt%以下。焙烧使铝土矿中高岭石相发生分解生成非晶态的偏高岭石,同时破坏矿颗粒致密结构,出现晶粒细化,但温度过高(650℃)会出现局部烧结现象。焙烧使一水硬铝石晶体破坏而活化,600℃时晶体破坏最完全,使600℃焙烧矿在相同溶出条件下溶出效果较原矿及其他焙烧矿优势明显,在溶出温度270℃、苛碱浓度245 g/L、石灰添加量14wt%的条件下,相对溶出率能达96%以上。

Facile synthesis of nanoceria by a molten hydroxide method and its photocatalytic properties

Ceria nanoparticles were facilely synthesized by a molten NaOH-KOH hydroxide flux method with the precursor of Ce(NO3)3·6H2O under different conditions in alumina crucibles or Teflon-lined stainless steel autoclave.The XRD patterns and TEM images show that both the crystal and particle sizes of synthesized nanoceria are around 10 nm.XPS results reveal that the nanoceria obtained in alumina crucible has a Ce3+fraction of 17.1%which is higher than that of ceria synthesized in the Teflon vessel,the FTIR spectra of nanoceria prepared in alumina crucible show a stronger intensity of O-H stretching mode.UV-DRS and PL spectra results show that the nanoceria synthesized in alumina crucible with a calculated band gap of 2.9 eV has a wider responding light wavelength and a lower photogene rated electron-hole recombination rate,due to a higher concentration of oxygen vacancies(Ce^3+%).The photocatalytic results show that the degradation ratio and rate of the Rhodamine B(RhB)solution with the nanoceria synthesized in alumina crucible are 98.39%and 0.02919 min-1,both of which are larger than those of the ceria obtained from Teflon vessel.This method proves to be a simple and scalable way to synthesize nanoceria with rich oxygen vacancies and high photocatalytic activity.

低温磁化焙烧对高铁铝土矿溶出及磁选性能的影响

为实现高铁铝土矿铝铁元素的高效利用,采用“低温磁化焙烧-拜耳溶出-赤泥磁选”的方式处理高铁铝土矿,考察了焙烧温度、H2浓度及通入时间对高铁铝土矿溶出及磁选性能的影响。结果表明,焙烧过程中一水硬铝石脱水转变为过渡态Al2O3,矿物发生热破裂现象,比表面积增大,氧化铝溶出活性增加,在焙烧条件为焙烧温度530℃、H2浓度20vol%、H2通入时间5 min时,氧化铝相对溶出率可达97.65%。磁化焙烧过程中,针铁矿转变为赤铁矿,再由赤铁矿转变为磁铁矿,通过溶出解除了铝铁元素之间的嵌布关系,对焙烧矿的赤泥进行磁选,其铁精矿品位达62.05wt%,铁回收率为86.36%。

Molten salt synthesis of Z-scheme CeO_(2)/C_(3)N_(4) photocatalysts with excellent properties for removal of organic pollutants:Characterization,kinetics and mechanisms

In this work,we firstly synthesized a CeO_(2)/C_(3)N_(4) photocatalyst with Z-scheme heterojunction by a facile LiC-KCI molten salt method.The synthesized catalyst has an excellent quality for removing organic pollution of dyes and antibiotics in wastewater.As an example,the CeCN-1:5 prepared with a mass ratio of Ce_(2)(CO_(3))_(3)·xH_(2)O:C_(3)H_(3)N_(6)=1:5 exhibits a methylene blue(MB)removal capacity of 100%within 90 min and tetracycline(TC)removal capacity of 94.6%.After 4 cycles,the CeCN-1:5 keeps a removal efficiency of nearly 100%in 150 min for MB and 85.7%for TC.The kinetics study reveals that the MB removal process with the CeCN-1:5 fits the modified Elovich model with strong adsorption while TC removal fits the first-order model.The large surface area(238 m^(2)/g)and negative zeta potential(-39.3 mV)of CeCN-1:5 contribute to superior adsorption capacity to MB.However,the adsorption of TC is restricted due to the positive surface/pore potential in acidic solution.CeCN-1:5has combined Z-scheme heterojunction and exhibits a low recombination rate of electrons(e^(-))/holes(h^(+))and the photo-generated active radicals of·OH/·O_(2)^(-)that promotes the photocatalytic performance.This novel CeO_(2)/C_(3)N_(4) photocatalyst with an excellent photocatalysis removal activity has an enormous potential for photocatalytic applications.