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.     

市场经济与中国特色社会主义制度形成的逻辑关联

市场经济体制在实践和理论的确立和发展中促使中国特色社会主义制度发生深刻变化,市场经济体制是社会主义经济制度的内核。它带来了国家社会相互关系的重大调整,政党转型,有力促进了社会主义民主法制的科学健康发展;与此同时,中国特色社会主义制度抑制市场经济体制的弊端、发扬社会主义制度的优势。确立和完善社会主义市场经济体制,与中国特色社会主义的改革完善是同步的,市场经济的不断完善和巩固必然推动着中国特色社会主义制度的完善和巩固。实践证明,市场经济与中国特色社会主义制度之间有着无可分离的内在逻辑关联。     

核电站再循环供水系统瞬态流分析

与国内沿海核电站采用直流循环供水系统有所不同,内陆核电站采用单元制再循环供水系统.直流循环水系统设计中已应用成熟的无阀系统是否可以在内陆核电站应用,需要通过分析停泵水力瞬态过程来确定.通过对无阀系统进行停泵水锤计算,模拟该系统主要设备的工作过程,论证了无阀系统不可以应用于再循环供水系统.     

多媒体视频图文系统的研制

目的研制与开发高性能专用视频图系统,方法以图形处理器ＴＭＳ３４０１０为核心,设计高性能的视频图技术,作为系统的主要硬件支持,并设计专用的配套软件构成完整的应用系统。结果形成了一个多处理器硬件系统和多指令流。多数据流的软件系统,实现了图形处理器级的专用图系统。结论该系统图形变换功能强,处理速度快,是一个高性能视频图系统。     

未拆分混沌系统恒等自同步研究

基于He和Vaidya的同步充分必要条件，提出了一个解决未拆分混沌系统恒等自同步的方法。该方法将驱动系统与响应系统的误差动力系统的Lyapunov函数的导数分为小于0或等于0的自由项和大于0的强迫项。将驱动系统的变量替代响应系统的变量，使Lyapunov函数导数的强迫项变为0，响应系统与驱动系统达到同步。模拟结果表明，该方法能够实现反馈同步方案不能同步的Henon映射系统，并能使Bragg混沌系统同步过渡过程所占用时间减小到反馈同步过渡过程所花时间的12％。     

含有负弹性刚度负载的电液控制策略探讨

针对电液位置控制系统在负载弹性刚度含有负值时系统出现不稳定现象,以及外负载力方向切换时干扰大而导致系统定位刚度差等问题,对负载弹性刚度为负值的电液位置控制系统构成及其数学模型的分析。采用二阶微分正反馈补偿的方法可以消除负载弹性刚为负值时对系统造成不利的影响。液压弹簧刚度处于最小值时,系统稳定性差、响应慢,在此情况下对系统进行建模仿真,得到的系统特性曲线表明:采用二阶微分正反馈补偿后系统稳定且拥有足够的稳定裕量,系统能够达到3 Hz以上的频宽。     

最优化的量子操作

讨论物理系统在不同的正交态之间演化所需要的时间.首先讨论了两能级系统,随后进一步讨论多能级系统.发现对多能级系统而言,在任意两个正交态之间演化的时间是两能级系统的2倍.这有利于在量子调控时,进行最优化的量子操作.     

全流-双循环地热发电系统分析

采用全流-双循环地热发电系统对中低温地热水进行利用发电,并与闪蒸蒸汽系统进行比较.理论推导闪蒸蒸汽系统的最佳闪蒸温度,分析比较了全流 双循环系统中各部分的损失,进而提出了降低换热器端差,以减少损的措施.在既定的地热水参数条件下,根据系统模型对全流 双循环系统和闪蒸蒸汽系统进行热力计算.结果显示：全流-双循环系统的最大发电功率比闪蒸系统的最大发电功率高出12.7%; 全流-双循环系统的功率随着低温工质蒸发温度的升高而增大;闪蒸蒸汽系统的功率随着闪蒸压力的增大呈先上升后下降的趋势.     

Study on Multi-agent Systems with Colored Petri Nets

The approach to model multi-agent systems with hierarchical colored Petri nets is introduced. In a multi-agent system, every agent is modeled with colored Petri net system, and the colored Petri net system of the multi-agent system is a hierarchical colored Petri net system, such that the agents planning deadlock detection and avoidance, can be analyzed with the Petri net system.     

可产生多翼吸引子的混沌系统及其电路实现

构造一个只有一个零平衡点的新混沌系统,与广义Lorenz系统族相比,该系统可以产生单、双、三及四翼的混沌吸引子.研究表明:当参数d=2时,其平衡点为鞍结点;当参数d=5时,其平衡点为鞍焦点,且系统的散度随着参数d的变化而改变,不是一个固定值.在Multism 12仿真平台上设计该系统的电子电路,仿真结果与数值仿真、动力学特性分析结论一致,进一步验证该混沌系统的混沌特性.     

人工内分泌系统调节人工神经网络的控制模型

人体的内分泌系统是一个复杂的控制系统,与神经系统、免疫系统一起维持机体的内平衡.受内分泌系统与神经系统的相互作用机制启发,提出一种内分泌系统调节神经网络系统的EMNCS(endocrine modulated neural control system)控制模型.EMNCS模型中,内分泌系统可以根据环境变化动态调节神经网络系统,达到动态控制的目的.把该模型应用于动态环境下的机器人控制系统,实验表明,EMNCS模型能有效提高机器人在动态环境下的适应能力.