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.     

液压振动技术在合金钢连铸机上的应用与研究

液压振动技术在连铸生产过程中得到广泛应用,主要是因为它的振幅、振频和振动波形可根据实际生产需求,作相应调整,可实现高频小振幅非正弦振动,大大提高了连铸坯的表面质量和内部质量。同时,本文列出了液压振动在使用过程中存在的问题,对其他钢厂使用液压振动技术具有一定的指导意义。     

互联电网低频振荡产生的机理及其抑制措施

总结了电力系统低频振荡的国内外现状,并在分析了电力系统低频振荡的数学模型的基础上,得出用PSS来抑制低频振荡的有效性,同时指出随着FACTS技术的发展,今后协调PSS和FACTS各个控制器之间的控制作用是彻底解决低频振荡问题的关键.     

反扰力振动控制研究及应用

根据谐波反谐波原理，提出了反扰力振动控制，即通过施加一个与原扰力在相位上相反的控制力，消除结构中扰力的影响。对激振源为电机的系统而言，反扰力振动控制就是利用电机本身产生反扰动力矩，去消除电机自身产生的扰动力矩。此法被应用于实际消振工程，获得比较理想的振动控制效果。     

一类二阶非线性差分方程解的振动性

对一类二阶非线性差分方程的解给出了几个振动或非振动的判定定理，并举例说明了定理的应用。     

汽轮发电机轴系扭振的机理研究

导出了多质块轴系的扭振模式解耦等效二阶模型，用复数力矩系数法分析了串补电容引起的轴系扭振机理和直流输电系统引起的轴系扭振机理，揭示了上述两种情况下轴系发生扭振的条件，为复杂系统的轴系扭振问题的计算机分析研究奠定了基础。     

高压瞬态过程压力振荡抑制技术研究

压力振荡抑制技术是再生液体发射药火炮（RLPG）技术的难点之一。报道通过改变再生喷射活塞系统机械振动的固有频率,可破坏RLPG压力振荡的激励机制。试验表明：利用此方法可有效抑制压力振荡的幅值。研究结果对再生式液体发射药火炮内弹道设计有指导意义。     

基于强迫振荡技术的传感器测量电路的设计

设计一种基于强迫振荡技术的呼吸阻力数据采集系统的传感器测量电路模块。采用一个三通分流器一端分别固定连接着压力、流量传感器,其中与流量传感器必须是水平连通的,一端连接呼吸机,另一端三通分流口留着用于连接强迫振荡发生器。压力传感器在使用之前要进行输入与输出关系的线性定标工作。最后分别在两个传感器输出端设计一个低通滤波器用于滤除各种杂波成分。试验结果表明,该传感器测量电路模块能有效地实时监测到经受试者呼吸系统反馈的振荡压力与振荡流量信号,并且制作简单。     

The northern annular mode: More zonal symmetric than the southern annular mode

Fan （2007） recently documented the zonal asymmetry of the Antarctic oscillation （AAO） in the austral winter. In this research, the zonal asymmetry of the northern annular mode, or the Arctic oscillation （AO）, in the interannual variability is studied for the boreal winter. It is shown that there is zonal asymmetry of the AO as well, similar to the case of the Antarctic oscillation （AAO）. However, the zonal asymmetry of the AO is considerably weaker than that of the AAO. This is far beyond the speculation, since the zonal asymmetry of the geography is larger in the Northern Hemisphere than the Southern Hemisphere. The Western and Eastern Hemispheres portions of the AO are correlated at 0.54 for 1959-1998, comparing with 0.23 for the case of the AAO. The authors also discussed the physical reason for this inter-hemispheric difference, and partly attributed it to the El Ni~o and Southern Oscillation （ENSO） cycle which may be represented by the SO index. It is indicated that the SO associated sea-level pressure （SLP） patterns are more zonal symmetric in the high latitudes of the Northern Hemisphere than the Southern Hemisphere.     

不带导流板矩形腔的流激振荡的频率特性

通过试验发现不带导流板矩形腔的流激振荡问题中,存在两种机理的振荡模式－腔的深度方向上驻波振荡和流体动力振荡,分析,探讨了不同气流迎角,不同腔深情况下的两种振荡频率的变化规律。从中得到如下结果：（１）驻波振荡频率几乎不随流速迎角的变化而变化,但随腔深、腔口截面积的增大而减小;（２）流体动力振荡频率所对应的Ｓｒ近似为一常数,不随流速变化,但随迎角的增大而减小。     

对氨基苯磺酸—溴酸钾—硫酸—丙酮在邻菲哕啉合铁（Ⅱ）催化下的B—Z振荡反应

研究报道了邻菲啰啉合铁(Ⅱ)催化下的化学振荡反应，对振荡的影响因素进行了研究和讨论．运用正交实验法确立了振荡反应进行的有效浓度范围．获得振荡的诱导期和周期与反应物浓度之间的变化趋势曲线，以及振荡反应在诱导期和振荡期的表观活化能．根据反应过程中的现象和实验数据，建立了振荡反应的模型和反应机理，进而为反应过程和机理研究提供一些实验依据。