Micro-Locational Fine Dust Prediction Utilizing Machine Learning and Deep Learning Models

Given the increasing number of countries reporting degraded air quality,effective air quality monitoring has become a critical issue in today’s world.However,the current air quality observatory systems are often prohibitively expensive,resulting in a lack of observatories in many regions within a country.Consequently,a significant problem arises where not every region receives the same level of air quality information.This disparity occurs because some locations have to rely on information from observatories located far away from their regions,even if they may be the closest available options.To address this challenge,a novel approach that leverages machine learning and deep learning techniques to forecast fine dust concentrations was proposed.Specifically,continuous location features in the form of latitude and longitude values were incorporated into our models.By utilizing a comprehensive dataset comprising weather conditions,air quality measurements,and location properties,various machine learning models,including Random Forest Regression,XGBoost Regression,AdaBoost Regression,and a deep learning model known as Long Short-Term Memory(LSTM)were trained.Our experimental results demonstrated that the LSTM model outperforms the other models,achieving the best score with a root mean squared error of 23.48 in predicting fine dust(PM10)concentrations on an hourly basis.Furthermore,the fact that incorporating location properties,such as longitude and latitude values,enhances the overall quality of the regression models was discovered.Additionally,the implications and contributions of our research were discussed.By implementing our approach,the cost associated with relying solely on existing observatories can be substantially reduced.This reduction in costs can pave the way for economically efficient fine dust observation systems,ensuring more widespread and accurate air quality monitoring across different regions.

Estimation of Fine Dust Particles Distribution in Machining Workshop Based on COwZ Model

Fine dust particles （diameter is less than 2.5 μm） generated during machining processes,especially dry cutting,are harmful to operators,because they remain suspended in the air for long time and have marked concentration gradients in workshop.Hence studies about cutting dust source states and indoor air quality prediction have been developed.However,few researches focus on the distribution state of the cutting dust,dynamic status of fine dust particles,and environment estimating of the machining workshop.The machining workshops have diversified architectural structures,complex working conditions,so the dust emission is sensitive dynamic.According to these features,after analysis of the static and dynamic influence factors,this paper proposes a method and establishes a model to estimate the fine dust particles distribution based on COwZ （COMIS （conjunction of multizone infiltration specialists） with sub-zones） model when only dry cutting is processed just needing various working parameters.And two key technologies are discussed：the description of the machine tools using sub-zones of COwZ model considering the local obstacle effects of machine tools themselves;description and implementation of dynamic process of cutting dust emission with a new concept of equivalent source strengths.At last,multi-point experiments in a hybrid ventilation machining workshop prove the method is practical.Good agreement was observed between the estimation results and the experimental measurements for the investigated conditions.The proposed method can supply reference data for green manufacturing.

Preparation of La _(0.9)RE_(0.1) MnO_3 Ultra fine Particles Used for CH_4 Oxidation

A technique for preparing perovskite type oxides was developed. By this technique, ultra fine particles of La 0.9 RE 0.1 MnO 3 (RE: Y, Ce, Pr, Sm, Gd,or Dy) with high surface area and single perovskite structure were prepared, and the series of La 0.9 RE 0.1 MnO 3 catalysts were studied experimentally. The so prepared ultra fine particles exhibites high catalytic activity for CH 4 total oxidation. The ultra fine particles of La 0.9 RE 0.1 MnO 3 (except for La 0.9 Pr 0.1 MnO 3) prepared by this method are thermally much more stable than LaMnO 3. Of the La 0.9 RE 0.1 MnO 3 series, La 0.9 Y 0.1 MnO 3 is most thermally stable, and La 0.9 Y 0.1 MnO 3 or La 0.9 Gd 0.1 MnO 3 (varies with calcination temperature) exhibits the highest catalytic activity for total oxidation of methane. The specific surface area of La 0.9 Y 0.1 MnO 3 calcined at 1000 ℃ reaches 14.9 m 2·g -1 , while the specific surface area of LaMnO 3 calcined at the same temperature is only 1.8 m 2·g -1 .

A Study on the Effect of Low Calcium Ultra-fine Fly Ash as a Partial Sustainable Supplementary Material to Cement in Self-compacting Concrete

The aim and scope of the present study were to determine the efficacy of UFFA in evaluating the workability,static and dynamic stabilization properties,retention period,and slump loss of SCC systems in their fresh state,as well as their compressive strength at various ages.Microstructure(SEM and XRD)of blended SCC systems were studied.Also,the thermogravimetry behavior of blended SCC specimens were researched.According to the evaluated results,incorporating up to 20%UFFA into fresh concrete improved its performance due to its engineered fine particle size and spherical geometry,both of which contribute to the enhancement of characteristics.Blends of 25%and 30%of UFFA show effect on the water-binder ratio and chemical enhancer dosage,resulting in a loss of homogeneity in fresh SCC systems.The reduced particle size,increased amorphous content,and increased surface area all contribute to the pozzolanic reactivity of the early and later ages,resulting in denser packing and thus an increase in compressive strength.The experimental results indicate that UFFA enhances the properties of SCC in both its fresh and hardened states,which can be attributed to the particles’fineness and their relative effect on SCC.

Corrosion behavior of ultra-fine grained industrial pure Al fabricated by ECAP

Corrosion behavior of ultra-fine grained(UFG) industrial Al fabricated by equal channel angular pressing(ECAP) for 16 pass times was investigated by potentiodynamic polarization test,potentiostatic polarization test,electrochemical impedance spectroscopy(EIS) measurement,immersion test and surface analyses (OM and SEM). The microstructures including grain size,grain boundaries and dislocations were also observed by TEM. The results show that the UFG industrial pure Al has more positive pitting potential,less corrosion current density and five times larger passive film resistance compared with the coarse grained(CG) one. It was found that the increased pitting resistance is profited from the more stable passive film kept in the Cl-aggressive solution due to more grain boundaries,larger fraction of non-equilibrium grain boundaries and residual stress of the UFG industrial pure Al.

SYNTHESIS OF ULTRAFINE PLZT POWDER BY A SIMPLE CO-PRECIPITATION METHOD

Starting from cheap inorganic salts , ultrafine P L Z T po w ders were synthesized by a co pre cipitation m ethod . The results show that the precursor precipitate obtained by the co precipita tion method transfor ms co m pletely to P L Z T phase by calcining at 420 ℃ for 4 hours , about300 ℃low er than the nor m al transform ation te m perature of P L Z T obtained by m ixed oxidemethod . The effect of residual N H4 N O3 in the precursor precipitate on transfor m ation te m perature of the P L Z Tpow der w as investigated . The residual N H4 N O3 in the precursor po w der can reduce further the P L Z Ttransfor m ation tem perature to about 300 ℃, but a sm alla mount of Zr O2 and Pb Ti O3 re m ained . By a proper control of the synthesizing route , a P L Z T po w der with a pri m ary particle size of 10 n m and an agglom eration size of 0 3 μm hasbeen produced .

Ultra fine grinding of silver plant tailings of refractory ore using vertical stirred media mill

Ultra fine grinding of the plant tailings of a refractory silver ore was studied using a laboratory type vertical stirred media mill. Preliminary tests confirmed that ultra fine grinding substantially improves the extraction of silver from the tailings in cyanide leaching （i.e. 36% Ag extraction rate from the as-received tailings with d80 of 100 μm, c.f. 84% extraction rate after ultra fine grinding of the tailings with ds0 of 1.2 pro）. In the ultra fine grinding tests, the effects of ball diameter （2-4.5 mm）, stirring speed （200-800 r/m/n） and ball charge ratio （50%-80%） on the fineness of grind （ds0, ~tm） were investigated through a Box-Behnken design. Increasing stirrer speed and ball charge ratio decreased fineness of grind while larger balls resulted in the coarser products. The tests demonstrated that a fineness of grind less than 5 μm can be achieved under suitable conditions. Analysis of stress intensity indicated an optimum range of stress intensity of （0.8-2）× 10^- 3 μm for all power inputs.

MICROSTRUCTURE TRANSFORMATION IN THE WELDING HEAT AFFECTED ZONE OF 800MPa GRADE ULTRA FINE STRUCTURED STEEL

The transformation behavior and microstructure development in the heat affected zone(HAZ)of 800MPa grade ultra fine structured steel was investigated.It was found that the HAZ has intermediate temperature transformation characteristics in a wide range of cooling rates,with the bainite sheaves consisting of bainite ferrite plates without carbide precipitation and retained austenite in the fast cooling regime.At relatively high cooling rates,which corresponded to low heat inputs,the hardness of the simulated HAZ was above that of the base metal.When the cooling rate was below 9C/s,the welding HAZ would have an obvious softening.The analysis of transformation rates in continuous cooling processes was completed by numerical differential method.The result indicated that the microstructure transformation rate of the HAZ in 800MPa grade ultra fine structured steel changed sharply to slow speeds when the cooling time t8/5 is longer than 7s.

Characterization of Ultra Fine Solids(BS) in Athabasca Bitumen

The ultra fine (<200 nm) inorganic solids (BS) were separated from bitumen which was washed by toluene and centrifugated at 2000 rpm. The result of PAS FTIR and image of TEM showed that the structure of BS particles was smiliar to that of kaolinite clay. On the surface of BS, both toluene insoluble organic matter and structural OH group are detected at the same time. The surface characteristics imparted a bi-wettable nature to the BS. As a result, the BS is able to stabilize fine water emulsion in the bitumen phase. The organic matter associated with BS is a possible factor of the fouling on catalyst and equipment.

Weld formation and heating mechanism in ultra-narrow gap withconstricted arc by ultra-fine granular flux

Ultra-narrow gap welding （UNGW） process with high stabilization, reliability and without spatter can be achieved with constricted arc by molten slag wall, which is made from melted flux. The experiments are carried out by changing voltage under different currents. The results indicate voltage range being fit for UNGW is about 22 -31 V under the current range of 200 -320 A. With the increasing of voltage, weld formation of UNGW has the law of lack of fusion on sidewall, good weld and undercut in turn under a certain current. In addition, the action relationships among arc, molten slag wall and sidewalls can be improved by properly adjusting voltage and current of arc, which makes cathode spot properly distribute in ultra-narrow gap. Therefore, the effective control of weld formation of UNGW has been achieved.

Optimal Conditions for Preparing Ultra-Fine CeO_2 Powders in A Submerged Circulative Impinging Stream Reactor

Cerium carbonate powders were produced in a submerged circulation impinging stream reactor （SCISR） from Ce（NO3）3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide （CeO2） powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce（NO3）3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor （STR）.

Microstructures and Hardness of 8CrWMoV Steel with Multiple Types of Ultra Fine Carbides

The structure and hardness of 8CrWMoV steel with multiple types of ultra fine carbides are studied after annealing, quenching and tempering in this paper. The results show that multiple types of carbides M3C, M7C3, M23C6, M6C and MC were observed in the annealed steel. Nucleation and coalescence of new carbides, partial dissolution of original carbides in γ phase region during annealing at 800～840℃, result in ultra-fine carbides. Average size of the carbides is0.33～0.34μm in the steel annealed at 800～840℃. Because M3C and M23C6 dissolve easily in austenite, the high hardness HRC63～65 can be obtained by quenching at 840～860℃. Un-dissolved carbides M6C and MC (VC) can effectively prevent the coarsening of austenitic grain, and conduce to obtain very fine martensite. The retained austenite can be easy to decompose during tempering at low and middle temperature due to the precipitation of multiple types of carbides and the good tempering-resistance of the steel is obtained. The microstructure and property of the steel after heat treatment can be accurately explained by calculating based on phase equilibrium thermodynamic.Key Words: 8CrWMoV steel, ultra-fine carbide, heat treatment, microstructure,

High Carbon Alloy Steels with Multiple Types of Ultra-fine Carbides and Their Characteristics

Under normal forging and annealing conditions, there are different ultra fine carbides (M3C, M23C6, M7Cj, M6C and MC) in high carbon alloy steels when alloy composition design is carried out properly. On the basis of carbides transformation orderliness, the alloy composition design of the high carbon alloy steels is conducted by phase-equilibrium thermodynamic calculation for Fe-Cr-W-Mo-V-C system. The nucleation and growth of new carbides, dissolution of previous partial carbides in these steels during annealing process, all these lead to ultra-fine distribution of carbides. Due to different crystal structures of carbides and different thermodynamics as well dynamics parameters of the carbides dissolution and precipitation, the range of quenching temperature of these steels is widened, and the good temper-resistance is obtained. The characteristics of heat treatment process and microstructure variance, and the carbides transformation for different temperature are explained by the phase-equilibrium component satisfactorily. Their bend and yield strength, flexibility and toughness all are advanced markedly comparing with that of kindred steels. Results of the applications have proved that the microstructure of ultra-fine carbides in these steels played importance roles in the enhancement of edginess and fatigue crack resistance of the die and knives.

DYNAMIC RHEOLOGICAL BEHAVIOR OF POLYPROPYLENE FILLED WITH ULTRA-FINE POWDERED RUBBER PARTICLES

Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.

Isothermal Growth Kinetics of Ultra-fine Austenite Grains in a Nb-V-Ti Microalloyed Steel

Ultra-fine austenite grains with size of i-3 μm were prepared in a Nb-V-Ti steel through repetitive treatment of rapid heating and quenching. A model for the growth kinetics of these ultra-fine austenite grains was successfully created through successive 2 processes, and the activation energy Q for growth was estimated to be about 693.2 kJ/mol, which directly shows the inhibition effect of microalloy elements on the growth of ultra-fine austenite grains.

Microstructures of ultra-fine grained FeCoV alloys processed by ECAP plus cold rolling and their evolutions during tempering

A new processing method,equal channel angular pressing(ECAP)plus cold rolling(CR),was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,and the effect of tempering treatment on the microstructure of FeCoV alloy produced by ECAP plus CR were investigated.The results show that an elongated substructure with a width of about 0.3μm is obtained after four-pass ECAP using Route A.Cold rolling after ECAP cannot change the morphologies of elongated substructure,and it results in higher fraction of high-angle boundaries and higher dislocation density compared with the identical ECAP without rolling.Subsequent tempering for 30 min at 853 K brings about many nano-phases precipitating at subgrain boundaries and insides the grains,and the size of precipitated phase is measured to be about 10 nm.Nano-phases grow up with increasing tempering temperature and equiaxed structure forms at 883 K.

Effect of welding heat input on HAZ character in ultra-fine grain steel welding

In this essay, we studied how heat input affected the microstructure, hardness, grain size and heat-affected zone(HAZ) dimension of WCX355 ultra-fine grain steel which was welded respectively by the ultra narrow-gap welding (UNGW) process and the overlaying process with CO 2 as protective atmosphere and laser welding process. The experimental results show when the heat input changed from 1.65 kJ/cm to 5.93 kJ/cm, the width of its HAZ ranged from 0.6 mm to 2.1 mm.The average grain size grew up from 2～5 μm of base metal to 20～70 μm and found no obvious soften phenomenon in overheated zone. The width of normalized zone was generally wide as 2/3 as that of the whole HAZ, and the grain size in this zone is smaller than that in base metal. Under the circumstance of equal heat input, the HAZ width of UNGW is narrower than that of the laser welding.

Preparation of Well Dispersed and Ultra-Fine Ce(Zr)O_2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.

Influence of Ultra-Fine B_4C and Nano-SiO_2 on the Properties of Alumina-Graphite Refractories

The role of nano-SiO 2 and ultra-fine boron carbide on the properties of alumina-graphite materials was investigated. The study showed that the ultra-fine boron carbide added modified the microstructure of residual carbon and promoted the chemical bond between residual carbon from phenolic resin and flake graphite. The carbon white could strengthen the residual carbon from phenolic resin. These two additives improved the mechanical properties of AG refractories at both room temperature and high temperature, and thermal shock resistance was improved noticeably. When the two additives were doped together, carbon white could retard the evaporation of B 2O 3. Thermal shock resistance was guaranteed with a smaller amount of ultra-fine boron carbide.

Three Dimension Monte Carlo Simulation of Austenite Grain Growth in CGHAZ of an Ultrafine Grain Steel

In the present research Monte Carlo technique was used to simulate the grain growth in heat-affected zone(HAZ) of an ultrafine grain steel. An experimental data based (EBD) model proposed by Gao was used to establish the relation between tMCS and real time temperature kinetics in our simulation. The simulations give out the evolution of grain structure and grain size distribution in HAZ of the ultrafine grain steel. A Microsoft Window based on computer program for the simulation of grain growth in the HAZ of weldment in three dimensions has been developed using Monte Carlo technique. For the system, inputting the temperature field data and material properties, the evolution of grain structure, both image of simulated grain structure and numerical datum reflecting grain size distribution can be produced by the program. The system was applied to the ultrafine grain steel welding, and the simulated results show that the ultrafine grain steel has large tendency of grain growth.