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.     

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.     

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.     

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.     

基于标记的图数据关键词查询方法研究

图数据关键词查询技术在结构化数据、半结构化数据和非结构化数据等领域具有良好的应用前景。随着需要解决问题规模的不断扩大,寻找top-k结果所花费时间将会增多。针对该问题,提出了一种基于标记查询优化的方法。该方法首先引入路径索引,通过输入一组关键词遍历路径索引,找到与关键词相关的结构子图;然后基于结构子图,找出当前最优结果,对当前最优结果,选择需要处理的路径进行标记;并设置该路径为无穷大,实现对当前最优结果的屏蔽,再在此基础上查找次优结果,直到top-k结果查询完毕;最后,基于测试数据集,验证该方法的有效性。     

基于多Agent系统的安全体系结构

提出一个允许Agent命名的安全体系结构．在开放的环境中,依靠这种方案提供MAS服务,允许Agent互相鉴定、允许交换数字签名通讯令牌及加密信息和数据．并研究在一个开放的Agent环境中Agent安全生存的可能性方案,给出一个独立完成的保护Agent和它们环境的体系结构．     

基于WEB的考试模型探讨

基于Web的考试系统是考试的发展方向，是远程教育的一个重要组成部分，它采用B/S模型，分析了基于Web系统的考试模型及功能，研究了考试系统实现的关键技术，并在具体系统中做了实现。     

略论比兴对诗歌艺术的影响

比兴是《诗经》重要的艺术手法，《楚辞》在《诗经》的基础上发展了比兴，这对于诗歌艺术都产生了重大影响。首先是引入了新的表现题材并加以扩大，其次发展到兴寄，进而发展到物我融一的艺术意境。可见，比兴不仅是《诗经》的艺术手法，还应该说是整个诗歌艺术中的重要的艺术手段，在诗歌史上起到了重要的作用。     

基于数据挖掘技术的客户关系管理系统研究

数据挖掘是CRM的核心,通过阐述数据挖掘的概念、过程、目标,分析基于数据挖掘的CRM的特征．并从客户生命周期和行业应用的角度探讨数据挖掘在客户关系管理系统中的应用．     

基于丢弃优先级的W-CHOKe算法研究

主动队列管理是实现网络拥塞控制的一种重要技术.本文针对主动队列管理算法中的CHOKe算法对非适应流的惩罚力度不够,不能够很好地实现带宽的公平分配这一问题进行深入研究.提出了一种改进的基于丢弃优先级的W-CHOKe算法,并利用网络仿真工具NS2对W-CHOKe算法的实现进行了仿真实验.结果给出W-CHOKe算法有效地控制了非适应流大量的挤占带宽,改进了CHOKe算法的性能.     

基于单目视觉的距离测量研究

针对目前单目视觉中依靠图像标定及其在双目视觉中立体匹配方法的不足,提出了利用单目视觉测量物体与镜头之间距离的测距方法。首先利用步进电机控制镜头移动来引起图像放大倍数的变化,然后根据图像的放大倍数和镜头移动的距离来计算镜头与物体之间的距离,距离计算的准确性已通过测量试验得到验证。     

基于struts+spring+hibernate框架的探讨与研究

在简要介绍了struts spring hibernate架构的基础上,详细地举出了一个用该架构开发的一个例子来讨论如何通过该架构进行应用程序的开发。     

球墨铸铁热浸镀铝的扩散行为

为了提高铸铁模具的抗高温氧化性能,通过制备热浸镀铝试样、对试样进行扩散退火,采用扫描电镜（SEM）观察Al元素的扩散行为,观察700℃下,不同扩散时间和3h下不同扩散温度的试样截面形貌.研究和探讨在不同温度下和不同保温时间条件下Al的扩散情况.结果表明：对热浸镀铝试样进行扩散,温度越高,Al的扩散速度越快;在相同扩散温度时,增加保温时间有利于Al元素在合金层中扩散,随扩散时间的增加,Al层逐渐变薄直至消失,Fe-Al合金层明显增厚.     

基于CSTA扩展接口的下一代网络融合业务合成研究

为了实现网络业务与电信业务的自动合成,在分析了已有Web Service技术及电信业务技术不足的基础上,提出了一种采用OWL-S扩展CSTA业务接口的方法.它丰富了OWL-S Profile文件的内容,改进了基于AI的前向链自动业务合成算法,并且实现了网络业务和电信业务的自动合成.最后通过一个自动股票查询系统实例验证了提出的接口扩展方法及改进算法的合理性.