Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation

The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.

Cooperative effect of sodium lauryl sulfate collector and sodium pyrophosphate depressant on the flotation separation of lead oxide minerals from hematite

As a cornerstone of the national economy,the iron and steel industry generates a significant amount of sintering dust containing both valuable lead resources and deleterious elements.Flotation is a promising technique for lead recovery from sintering dust,but efficient separation from Fe_(2)O_(3) is still challenging.This study investigated the cooperative effect of sodium lauryl sulfate(SLS,C_(12)H_(25)SO_(4)Na)and sodium pyrophosphate(SPP,Na_(4)P_(2)O_(7))on the selective flotation of lead oxide minerals(PbOHCl and PbSO_(4))from hematite(Fe_(2)O_(3)).Optimal flotation conditions were first identified,resulting in high recovery of lead oxide minerals while inhibiting Fe_(2)O_(3) flotation.Zeta potential measurements,Fourier transform infrared spectroscopy(FT-IR)analysis,adsorption capacity analysis,and X-ray photoelectron spectroscopy(XPS)studies offer insights into the adsorption behaviors of the reagents on mineral surfaces,revealing strong adsorption of SLS on PbOHCl and PbSO_(4) surfaces and remarkable adsorption of SPP on Fe_(2)O_(3).The proposed model of reagent adsorption on mineral surfaces illustrates the selective adsorption behavior,highlighting the pivotal role of reagent adsorption in the separation process.These findings contribute to the efficient and environmentally friendly utilization of iron ore sintering dust for lead recovery,paving the way for sustainable resource management in the iron and steel industry.

Service Function Chain Deployment Algorithm Based on Multi-Agent Deep Reinforcement Learning

Aiming at the rapid growth of network services,which leads to the problems of long service request processing time and high deployment cost in the deployment of network function virtualization service function chain(SFC)under 5G networks,this paper proposes a multi-agent deep deterministic policy gradient optimization algorithm for SFC deployment(MADDPG-SD).Initially,an optimization model is devised to enhance the request acceptance rate,minimizing the latency and deploying the cost SFC is constructed for the network resource-constrained case.Subsequently,we model the dynamic problem as a Markov decision process(MDP),facilitating adaptation to the evolving states of network resources.Finally,by allocating SFCs to different agents and adopting a collaborative deployment strategy,each agent aims to maximize the request acceptance rate or minimize latency and costs.These agents learn strategies from historical data of virtual network functions in SFCs to guide server node selection,and achieve approximately optimal SFC deployment strategies through a cooperative framework of centralized training and distributed execution.Experimental simulation results indicate that the proposed method,while simultaneously meeting performance requirements and resource capacity constraints,has effectively increased the acceptance rate of requests compared to the comparative algorithms,reducing the end-to-end latency by 4.942%and the deployment cost by 8.045%.

Enhanced visible-light photocatalytic oxidation capability of carbon-doped TiO_2 via coupling with fly ash

A carbon‐doped TiO2/fly ash support(C‐TiO2/FAS)composite photocatalyst was successfully synthesized through sol impregnation and subsequent carbonization.The carbon dopants were derived from the organic species generated during the synthesis of the C‐TiO2/FAS composite.A series of analytical techniques,such as scanning electron microscopy(SEM),attenuated total reflection‐Fourier transform infrared(ATR‐FTIR)spectroscopy,X‐ray photoelectron spectroscopy(XPS),and ultraviolet‐visible diffuse reflectance spectroscopy(UV‐Vis DRS),were used to characterize the properties of the prepared samples.The results indicated that C‐TiO2 was successfully coated on the FAS surface.Coupling between C‐TiO2 and FAS resulted in the formation of Si–O–C and Al–O–Ti bonds at their interface.The formation of Si–O–C and Al–O–Ti bonds gave rise to a positive shift of the valence band edge of C‐TiO2 and enhanced its oxidation capability of photogenerated holes as well as photodegradation efficiency of methyl orange.Moreover,the C‐TiO2/FAS photocatalyst exhibited favorable reusability and separability.This work may provide a new route for tuning the electronic band structure of TiO2.

高填充量耐油乙烯-醋酸乙烯酯共聚物电缆材料的制备及性能

应用聚硅氧烷低聚物(FPSO)对二氧化硅(SiO_2)、氢氧化铝(ATH)和氢氧化镁(MH)的混合物进行改性,并将改性后的无机混合物与乙烯-醋酸乙烯酯共聚物(EVA)进行熔融共混复合,制备出无机物填充量达50%的EVA电缆材料。采用扫描电镜(SEM)、差示扫描量热仪(DSC)、旋转流变仪、万能试验机和极限氧指数测试仪对EVA电缆材料的结构和性能进行表征与测试。SEM结果显示,FPSO的引入促进了高含量无机混合物在EVA基体中的分散,材料燃烧后的炭渣表面结构完整;DSC测试结果表明,FPSO含量较低时,EVA的结晶能力提高,有利于电缆材料力学性能的改善。流变测试结果揭示,FPSO的引入在削弱填料间相互作用的同时提高了无机粒子与基体间的界面黏结力,有利于提高材料的耐油及阻燃性能;当FPSO的质量分数为0.48%时,电缆材料具有较好的力学、耐油及阻燃性能。

Three-point bending of honeycomb sandwich beams with facesheet perforations

A novel square honeycomb-cored sandwich beam with perforated bottom facesheet is investigated under threepoint bending,both analytically and numerically.Perforated square holes in the bottom facesheet are characterized by the area ratio of the hole to intact facesheet（perforation ratio）.While for large-scale engineering applications like the decks of cargo vehicles and transportation ships,the perforations are needed to facilitate the fabrication process（e.g.,laser welding）as well as service maintenance,it is demonstrated that these perforations,when properly designed,can also enhance the resistance of the sandwich to bending.For illustration,fair comparisons among competing sandwich designs having different perforation ratios but equal mass is achieved by systematically thickening the core webs.Further,the perforated sandwich beam is designed with a relatively thick facesheet to avoid local indention failure so that it mainly fails in two competing modes：（1）bending failure,i.e.,yielding of beam cross-section and buckling of top facesheet caused by bending moment;（2）shear failure,i.e.,yielding and buckling of core webs due to shear forcing.The sensitivity of the failure loads to the ratio of core height to beam span is also discussed for varying perforation ratios.As the perfo-ration ratio is increased,the load of shear failure increases due to thickening core webs,while that of bending failure decreases due to the weakening bottom facesheet.Design of a sandwich beam with optimal perforation ratio is realized when the two failure loads are equal,leading to significantly enhanced failure load（up to 60%increase）relative to that of a non-perforated sandwich beam with equal mass.

Performance enhancement of sandwich panels with honeycomb–corrugation hybrid core

The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.

Analytical design of effective thermal conductivity for fluid-saturated prismatic cellular metal honeycombs

A comparative optimal design of fluid-saturated prismatic cellular metal honeycombs （PCMHs） having different cell shapes is presented for thermal management applications. Based on the periodic topology of each PCMH, a unit cell （UC） for thermal transport analysis was selected to calculate its effective thermal conductivity. Without introducing any empirical coefficient, we modified and extended the analytical model of parallel-series thermal-electric network to a wider porosity range （0.7 ~ 0.98） by considering the effects of two-dimensional local heat conduction in solid ligaments inside each UC. Good agreement was achieved between analytical predictions and numerical simulations based on the method of finite volume. The concept of ligament heat conduction efficiency （LTCE） was proposed to physically explain the mechanisms underlying the effects of ligament configuration on effective thermal conductivity （ETC）. Based upon the proposed theory, a construct strategy was developed for designing the ETC by altering the equivalent interaction angle with the direction of heat flow： relatively small average interaction angle for thermal conduction and relatively large one for thermal insulation.

Template-free synthesis of carbon doped TiO2 mesoporous microplates for enhanced visible light photodegradation

Titanium dioxide （TiO2） is widely employed as a solid photocatalyst for solar energy conversion and envi- ronmental remediation. The ability to construct porous TiO2 with controlled particle size and narrowed bandgap is an essential requirement for the design of highly efficient and recyclable photocatalysts. Here, we report a template- free acetic acid induced method for the synthesis of visible- light responsive carbon-doped TiO2 microplates with high crystallinity and mesoporous structure. It is shown that the electron-withdrawing bidentate carboxylate ligands derived from acetic acid can narrow the bandgap of TiO2 （1.84 eV） substantially. Moreover, the resultant microplate photo- catalysts exhibit excellent photocatalytic efficiency and solid-liquid separation performance, which will be bene- ficial for future industrial applications.

EXPERIMENTAL AND SIMULATED COMPRESSIVE PROPERTIES OF WORK-HARDENED X-TYPE LATTICE TRUSS STRUCTURES

The expanded metal sheets were folded with 11% work-hardening. These were sub- sequently used with resistance welding to construct X-type lattice truss sandwich panels having a core relative density of 0.17. The sandwich panels were tested in uniaxial compression and, for comparison, the method of finite elements was employed to simulate the measured compressive stress-strain curves. The peak compressive strength was 32% higher than that of pyramidal core sandwiches. The enhanced mechanical properties of the work-hardened X-Type lattice structures mainly originate from the contribution of straight struts with low degree of curvature and work hardening, rather than the two-dimensional staggered nodes.