具有良好可再生性的新型二氧化硅磁性氧化石墨烯纳米复合材料

Graphene oxide (GO) wrapped Fe₃O₄ nanoparticles (NPs) were prepared by coating the Fe₃O₄ NPs with a SiO₂ layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO₂ coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO₂ on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO₂ layer can effectively induce the GO nanosheets to completely wrap the Fe₃O₄ NPs, forming a core-shell Fe₃O₄@SiO₂@GO composite where Fe₃O₄@SiO₂ NPs are firmly encapsulated by GO nanosheets. The optimized Fe₃O₄@SiO₂@GO sample exhibits a high saturated adsorption capacity of 253 mg·g?1 Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.     

微波预处理对复杂铜矿磨矿及浮选动力学的影响

The effect of CaCO₃, Na₂CO₃, and CaF₂ on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe₃PO₇ and apatite was investigated. The results revealed that Na₂CO₃ had the most significant effect on iron recovery and dephosphorization, followed by CaCO₃, the effect of CaF₂ was negligible. The mechanisms of CaCO₃, Na₂CO₃, and CaF₂ were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe₃PO₇ was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO₃ reacted with Fe₃PO₇ to generate an enormous amount of Ca₃(PO₄)₂ and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na₂CO₃, the phosphorus in Fe₃PO₇ migrated to nepheline and Na₂CO₃ improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF₂ reacted with Fe₃PO₇ to form fine Ca₃(PO₄)₂ particles scattered around the iron particles, making the separation of iron and phosphorus difficult.     

不同硅饱和系数水榴石的碳酸化分解动力学

Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method, which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method. In this study, the effect of the silica saturation coefficient (x) on the carbonation of hydrogarnet was investigated from the kinetic perspective. The results indicated that the carbonation of hydrogarnets with different x values (x = 0.27, 0.36, 0.70, and 0.73) underwent two stages with significantly different rates, and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3. The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol, respectively. Moreover, the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.     

一种超重力燃烧合成制备高性能高熵合金的新方法

A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr_0.9FeNi_2.5V_0.2Al_0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.     

利用皮秒激光烧蚀制备非球形铝纳米颗粒

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl₃) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.     

窄板坯结晶器内连铸工艺参数对钢液流场的影响

Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min?1 and casting speed of 1.7 m·min?1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.     

电渣重熔脱硫技术研究进展

Electroslag remelting (ESR) gives a combination of liquid metal refining and solidification structure control. One of the typical aspects of liquid metal refining during ESR for the advanced steel and alloy production is desulfurization. It involves two patterns, i.e., slag–metal reaction and gas–slag reaction (gasifying desulfurization). In this paper, the advances in desulfurization practices of ESR are reviewed. The effects of processing parameters, including the initial sulfur level of consumable electrode, remelting atmosphere, deoxidation schemes of ESR, slag composition, melting rate, and electrical parameters on the desulfurization in ESR are assessed. The interrelation between desulfurization and sulfide inclusion evolution during ESR is discussed, and advancements in the production of sulfur-bearing steel at a high-sulfur level during ESR are described. The remaining challenges for future work are also proposed.     

Mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during high-temperature sintering

The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al₂O₃?Na₂O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaO·Al₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.     

含细夹层的分矿充填层中流动特性的可视化

Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.     

数据预处理在商业企业数据仓库的应用

数据预处理是数据挖掘过程中重要环节 ,对数据预处理技术进行研究具有现实意义。文章在介绍数据预处理方法的基础上 ,结合大型商业营销企业数据仓库数据的特点和数据挖掘过程中对数据的要求 ,详细论述了数据预处理技术在大型商业营销企业数据仓库中的应用 ,提出改善数据质量是预处理技术的关键。     

基于DataGuard的Oracle RAC高校数据保护研究

数据是高校管理信息化产生的最重要的无形资产,数据的丢失或者损坏都将极大地损害教学、管理和科研工作的正常开展．Oracle RAC是目前使用最为广泛的数据库集群化管理方式,在此基础上开展DataGuard数据保护技术的应用研究,可以弥补集群数据库环境在数据容灾、备份和故障恢复方面的不足,提升数据的安全性,确保高校各类应用系统的正常运行．     

人工智能赋能高校数据治理:逻辑、挑战与实践

随着人类社会逐步迈入以情感计算、自然语言处理等智能技术为核心支撑的人工智能时代,数据的战略资源地位日益凸显,数据治理已成为推进高校教育治理现代化的关键工具。人工智能赋能高校数据治理的基本逻辑主要体现在数据管理、数据质量、数据决策与数据服务4个层面。高校数据管理忽视“多方协同管理”、缺乏相对统一的数据质量标准、数据决策在权责限定与顶层设计方面存在缺失、数据服务潜能激发不力制约数据价值高效释放等可被视为人工智能赋能高校数据治理的现实挑战。对此,应创设落位智能共管的高校数据管理职能优化机制、完善校本化高校数据挖掘与共享质量标准、构建基于责权厘定的智能化数据决策体系、优化指向数据价值释放的智能数据服务体系。     

Microsoft Excel的数据库管理方法

从一般数据库管理的角度出发,论述Excel管理数据库的方法。这种“表格”式的数据库管理方法将提供给用户一种新颖的设计方法和简单的使用操作。具有很大的推广价值。     

中小油田地震数据计算机管理方法研究

石油勘探技术发展迅速 ,需要一个集地震、测井、地质 3种数据为一体的勘探数据库来支持新的研究工作 .对包括地震资料处理、解释等资料的存储、应用方法进行了探索 ,提出了一种适合于中小油田的地震数据管理方案 .通过分析地震资料处理、解释产生的各类数据及其特点 ,从存储管理方法、数据规范化、质量控制方法、应用支持方法、数据服务方法等方面进行了详细论述     

化工物性数据库CPPDB在IBM-PC/XT机上的实现

讨论了文题实现方法,介绍了该数据库的总体结构。CPPDB利用dBASE Ⅲ支持建库,数据独立性高,修改、扩充方便。CPPDB存储了468种物质的29种物性数据,具有较强的物性估算和图形输出功能。     

数据仓库数据加载技术

数据仓库中的数据不是传统数据库中数据的简单堆积，其数据的组织必须方便基于数据仓库基础之上的数据挖掘和商业智能工作，为决策者提供访问、分析及共享信息的能力，从而发挥数据仓库的真正功效。成功构造一个数据仓库的关键在于自始至终理解用户需要，紧紧围绕用户目标这一主题进行数据的搜集和存储。首先分析数据仓库的特点及拥有的数据类别及组成，重点介绍如何从现有数据库中有效地将数据引导至数据仓库的方法和策略，具体给出了数据仓库中5种不同类别数据的加载方法。     

大数据时代的数据挖掘技术与应用

随着数据挖掘技术研究的进步与发展,并伴随着大数据概念的提出,将为数据挖掘技术的发展和应用带来一个很大的机遇,数据挖掘技术将进入一个新的发展时期.文章全面介绍了大数据,数据挖掘的基本概念以及数据挖掘的分析方法,最后给出了大数据时代的挖掘技术的应用领域及将来发展方向.     

数据仓库清洗技术讨论

数据仓库建设过程中最关键的环节是数据集成,本文重点分析了数据清洗需要解决的问题及涉及的主要技术,针对数据库的数据模型与数据仓库模型的区别讨论了利用元数据的映射规则的数据清洗方法.     

数据挖掘和数据仓库的关系研究

阐述了数据挖掘和数据仓库的有关技术,研究了数据挖掘和数据仓库的相互关系,说明了数据挖掘系统和数据仓库应统一分析和设计.