Surface oxidation behavior of Mg-Y-Ce alloys at high temperature

After the Mg-Y-Ce magnesium alloy was exposed to air at a temperature up to 1173 K for 0.5 hours, the dense and compact oxide film formed on the surface. Accordingly, oxidation and ignition of magnesium alloys at elevated temperature was successfully retarded by the Y and Ce additions. Thermogravimetric measurements in air revealed that the oxidation dynamics curves measured at 673 and 773 K followed the parabolic-line law and the curve investigated at 873 K followed the complicate quartic law. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis indicated that the oxide film on the surface of Mg-Y-Ce alloys exhibited a duplex structure, which agreed with the results of thermodynamic analysis. The oxidation film included two layers: the outer layer was a multiple structure of Ce_0.202Y_0.798O_1.601 and Y₂O₃, and the inner layer mainly consisted of metal Mg and MgO.     

浅谈如何进行现代人力资源考核工作

现代人力资源考核是人力资源管理的重要方法，南钢改制后，为推进各级组织和领导提高人力资源管理水平，本文拟就把握现代人力资源考核的原则、方法和程序，考核标准与发掘员工能力之间的关系，增强考核的效度和信度，提高组织的工作效率和个人的综合素质等问题进行初浅的探讨。     

Influence of Rare Earth Elements on Luminescent Properties of Y2SiO5 ： Tb

Photoluminescent （PL） and cathodoluminescent （CL） properties of rare earths （Sc^3＋ , La^3＋ , Gd^3＋ and Lu^3＋ ） doped （Y0.97Tb0.03）2SiO5 were studied. Rare earth doping clearly influences PL and CL properties of Y2SiO5 ： Tb. For La^3＋ doped system, PL intensity increases nearly 10 % at x = 0.05 whereas for Lu^3＋ doped system, the intensity increases about 20% at x = 0.20. Gd^3 ＋ doping and Sc^3＋ doping reduce the intensity; at x = 0.3, it is reduced about 30% for Gd^3＋ doped system and about 15 % for Sc^3＋ doped system, respectively. Quenching concentration of activator became higher in rare earth doped samples, which may be understood by that the rare earth dopants might dilute the concentration of the activator. Additionally, doping also influences the color saturation of Y2SiO5 ： Tb. Sc^3＋ , La^3＋ , and Gd^3 doping improve the color saturation, whereas Lu^3＋ doping decreases the color saturation. CL measurements show that CL intensity increases for all rare earths doped systems. The energy transfer from Gd^3＋ to Tb^3＋ was discussed.     

Optimum Design of Welded Steel Plate Girder Bridges Using a Genetic Algorithm with Elitism

The genetic algorithm (GA) is a general optimization technique that has some unique features that are especially suitable for structural engineering problems. This work uses a simple GA with elitism to find the optimum design of welded steel plate girder bridges. The objectives are to minimize the weight and the cost of the girders. Two types of plate-girder bridges are studied: a single-span bridge and a two-equal-span continuous bridge. Bridges with various span lengths, in increments of 20?ft, are investigated; results are tabulated, parametric studies are made, and meaningful conclusions are drawn.     

员工流动成本的分析与测算

借鉴了国内外的一些研究成果。从概念、组成等角度分析了员工流动成本。提出了狭义和广义的员工流动成本计算公式，最后就降低员工流动成本提出了若干措施。     

Existing State and Partitioning of Rare Earth on Weathered Ores

The existing state and partitioning of rare earth （RE） on weathered ores in Longnan County（LN）, Xingfeng County（XF） and Ninghua County（NH） were characterized systematically by standard geological analytical methods. It is found that RE in the weathered rare earth ores exist as four phases： （a） water soluble, （b） ion-exchangeable, （c） colloidal sediment （oxides）, （d） minerals, in which mainly as ion exchangeable phase, accounting for nearly 80% of total RE, with about 20% in the form of colloid sediment phase and mineral phase, but very little as aqueous soluble phase. These rare earth partitioning were mainly chosen mid-heavy RE elements, occupying above 60%, but not equal in the four phases. The mid-heavy RE elements were primarily enriched in the ion exchangeable phase up to 40%, while the containment of cerium dioxide is below 2 %. The cerium deficiency occurs in the ion exchangeable phase in weathered ore. It results from that the Ce^3＋ is oxidized into Ce^4＋ and changes into CeO2. For LN ore, the containment of Y is high in weathered ore because Y-minerals are abundant in original rock.     

Study on BSTO/MgO Ferroelectric Materials for Phase Shift Doped with Rare Earth Oxides

Phasedarrayantennascansteerthetransmitted orreceivedsignalswiththeadvantagesoffastscan ning,multipletargetstrackingandgoodanti jam ming.Theseantennasarecurrentlyconstructedusing ferritephaseshiftingelements,whicharecostly,large andheavy.Therefore,theirmil…     

Sol-Gel Synthesis and Luminescent Characteristic of Doped Eu^3 ＋ Silicate-Silica Phosphor

Silicagelphosphorsdopedrareearthionshave attractedgreatattentionofmanyresearchersdueto theseadvantages,suchashighersamplehomogeneity,purityandstable,efficientandenvironmentallyfriend lyphotoluminescencematrixmaterials,whichisless toxicleadtonetconversione…     

济钢烧结厂节能降耗的探索与实践

鉴于我国目前能源比较紧缺的状况,如何降低能源消耗及实现能源的循环利用,是各行业的共同努力方向。济钢烧结厂近年来从工艺技术和工艺改造等方面着手,不断挖掘降低工序能耗的潜力,经过不懈的努力,取得了比较明显的效果。     

合金元素铌对新锆合金耐蚀性能的影响

用SEM波谱分析手段,定性研究了合金元素铌在新锆合金中的存在方式.结果表明,添加的合金元素铌主要存在于LAVES相中,在α-Zr中的固溶度则小于100 μg·g-1.由此可推断,铌和铁、铬共存时,优先形成沉淀相,造成它在α-Zr中固溶量的降低.结合2种新锆合金(低铌NZ2 ,高铌NZ8)板材在360 ℃含锂水中和400、500 ℃蒸汽中的堆外高压釜腐蚀性能方面的以往研究结果,对铌的作用进行了唯象的讨论,并指出,认知固溶于α-Zr中微量的铌和大量存在于LAVES相中的铌对腐蚀机理的影响是今后研究的重要课题.