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.     

基于实时数据库的分布式城市交通监控系统设计

采用实时数据库技术、分布式技术、PC and Sun Workstation结构和Visual C 6.0,设计了基于Windows平台的实时城市交通监控系统,监测系统则由一个交通监控中心和若干分中心组成.该系统的监控子系统由事件自动检测系统、通讯设备、报警系统、指示装置和实时数据库组成,事件自动检测系统由实时交通信息的采集单元和检测交通事件算法组成.监控系统有效地减少网络开销,增加系统的实时性,提高事件自动探测的工作效率.     

Google Earth在交通信息服务系统中的应用研究

通过将海量的高分辨率卫星遥感图与航拍图映射到三维的地球模型中,Google Earth(GE)为ITS的各种应用提供了全新的地理信息平台。描述并分析了GE的主要功能及其编程接口,建立了基于GE的实时动态交通信息服务系统的分布式系统架构,并开发了相应的原型系统。运行结果表明,原型系统达到了设计目标,与传统基于GIS的交通信息服务系统相比,具有更加生动的交通与地理信息表达方式、用户与开发者友好等优点。     

实时数据库在分布式广播电视监测调度指挥系统中的应用与设计

从数据模型的确定,存储介质和存储结构的选择,实时数据库的数据通信设计,实时数据库的更新管理,实时数据库的分布式设计5个方面介绍实时数据库技术在分布式广播电视安全播出监测调度指挥系统中的应用与设计.实时数据库的应用有效地解决了当前监测调度指挥系统存在的调度指挥与监测之间的连动性、协调性差的问题,最大化地发挥了广播电视调度指挥监管效能.     

基于局域网的相邻路口交通灯协调控制系统的设计

为了缓解城市交通拥堵等交通现状,研制了由欧姆龙PLC做下位机控制器,组态王做远程监控软件的双路口协调控制交通灯实验系统。该实验系统具有实时车流量检测、分时段控制、手动控制、无线遥控控制、急车通行功能。监控计算机通过局域网对交通路口进行远程监控。实验证明,该系统稳定性好,功能完备,人机界面友好,可减少堵塞现象和交通事故,具有很好实际应用价值。     

基于CAN总线的汽车检测线计算机控制系统

控制器局域网络是一种能有效支持分布式控制或实时控制的串行通信网络,具有高性能和高可靠性的特点。文章介绍了一种基于CAN总线,以嵌入式系统为工位机的汽车检测线计算机控制系统,详细论述了该计算机控制系统的结构,着重分析了系统的硬件设计和软件设计;该方案成本低,可靠性高,能更好地满足汽车综合性能检测的实际需要。     

城市路口智能协管系统的应用研究

针对我国城市路口交通目前所存在的问题,该文对现行的城市路口交通监控系统进行了深入研究和分析,现提出了一种新型的城市路口智能协管系统,该系统不仅对路口往来的车辆和行人进行了实时有：故的监管,还能为城市交通监管部门提供实时可靠的路口交通信息。与现有的交通监管系统相比,该系统具有智能性、高效性、创新性等优点,为城市交通的智能化建设提供了有力的保障。     

Control system design of hybrid fuel cell city bus

This paper introduced the design of the hybrid powertrain of the Fuel Cell City Bus demonstrated in 2008 Beijing Olympic Games. The configuration of the hybrid fuel cell powertrain was introduced. The safety of hydrogen storage and delivery system, the hydrogen leakage alarm system were developed. The real-time distributed control and diagnosis system based on the Time Trigger Controller Area Network (TTCAN) with 10 ms basic control period was developed. The concept and implementation of processor (or controller) monitor and process (or task) monitor technique based on the TTCAN were applied in this paper. The fault tolerant control algorithm of the fuel cell engine and the battery management system were considered. The demonstration experience verified that the fault tolerant control was very important for the fuel cell city bus.     

一种分布式冗余的实时数据存储检索机制

为解决传统集中式实时数据库吞吐量、容错性、可扩展性不足的难题,提出一种基于分布式架构、具备多重副本管理功能的实时数据存储检索机制.该机制结合一致性哈希算法与基于多版本控制的数据组织方案,从实时数据的存储、管理、查询三方面进行设计和优化,在保证数据存取实时性的基础上实现了备份同步、一致性修复等核心功能,从而有效提高了实时数据库的海量数据存储与处理能力,为实时数据库向分布式存储、多重冗余备份、系统规模动态调整等方向的转变奠定了基础.通过在原型系统中测试验证,结果表明该机制能够达到设计预期目标和性能要求.     

基于TCP/IP协议的智能公交管理系统应用

运用JAVA开发工具,以Microsoft Access作为后台数据库,基于TCP/IP短信平台设计一个GPS/GIS/GSM智能公交管理系统.该系统由监控中心、GPS车载终端和GSM网络通信3大模块组成,实现了车辆的准确定位、车辆的实时监控和车辆调度等公共交通管理要求.该系统经测试定位误差较小,能够满足公共交通管理的使用要求.     

基于知识的自适应电梯群控制策略

为获得更低的平均候梯时间和长候梯率,提出一种基于知识的自适应电梯群控制策略.该控制策略汇集了区域权重控制算法、电梯运行操作知识以及层站召唤再分配规则,基于自适应的长候梯时间阈值,对长候梯层站召唤执行再分配操作,凸现了电梯群控制策略对复杂电梯交通的自适应性.与经典THV算法、基于知识的区域权重控制算法、人工免疫动态优化算法比较,该方法能获得更低的平均候梯时间和长候梯率.同时,其自适应能力使得该控制策略更易于应用在实际电梯群控制系统中.