Oxidation kinetics and high temperature in-situ observation of the oxidation behaviour of NbSi_2 at 1023 K

Pest oxidation has been known for a long time in refractory transition-metal disilicides such as NbSi2 and MoSi2[1―4]. However, the origin of pesting reaction of these materials is still under debate. Although the pesting phenomenon in NbSi2 has been reported in several works[5―7], a direct study of the mechanism is scarce at the moment. Compared to NbSi2, pesting in MoSi2 has received relatively extensive attention. Mckamey et al.[8] showed fragmentation near 773K occurred easily in as…     

企业慈善——新时期我国企业与社会的双赢选择

企业慈善是企业与社会的双赢选择。企业慈善可促进慈善事业的发展，达到整合社区资源、促进社区发展的目的，在更为广阔的社会系统中表达一种“关爱与和谐”的理想与信念。同时，企业慈善有利于提升企业自身形象，增进企业内部凝聚力，培养优秀的企业文化。当前我国企业慈善的发展现状不容乐观。我国企业应该大力参与慈善事业，开创社会主义和谐社会下企业与社会的双赢局面。     

有机体系中制备纳米TiO2掺杂Ni电极及其性能测试

在无隔膜电解槽中合成金属醇盐NiTim(OR)_3m+1(acac)_m+1，直接水解形成凝胶，干燥后在550 ℃煅烧2 h, 制得纳米Ni/TiO₂粉体。通过电合成与沉积得到高活性的纳米Ni/TiO₂修饰电极，采用循环伏安比较研究了TiO₂和Ni/TiO₂电极在H₂SO₄溶液中的氧化还原行为。结果表明，所得前驱体中含有乙酰丙酮基[acac-]，所得纳米粉体粒径为20 nm；Ni/TiO₂电极在1 mol/L H₂SO₄溶液中有两对氧化还原峰，掺杂Ni电极的放电电流明显增大，达到75 mA ·cm_-2。     

酸性蒽醌绿合成新工艺的研究

由1,4,5,8—四羟基蒽醌和对甲苯胺为主要原料,在一个反应器内同时完成了缩合和磺化两步单元反应,合成酸性蒽醌绿染料,并对其反应条件对产物收率的影响进行了研究,确定了最佳合成工艺条件(反应时间16 h、反应温度120℃、原料的配比1:2.2)。     

混凝电解气浮-吸附过滤处理洗染废水

采用混凝电解气浮-吸附过滤法处理洗染废水.试验结果表明:混凝电解气浮过程中,采用石墨作阴极,铁作阳极,电解电压一般控制在8~11 V,电能消耗约0.08 kW h/m3,CODC r可去除30%以上;吸附过滤过程选用新鲜粉煤灰作为吸附材料,粒度为0.3 mm,废水在吸附柱中的停留时间为2 h,CODC r可以去除50%以上.     

A continuous-wave hybrid AlGaInAs-silicon evanescent laser

We report a novel laser architecture, the hybrid silicon evanescent laser (SEL), that utilizes offset AlGaInAs quantum wells (QWs) bonded to a silicon waveguide. The silicon waveguide is fabricated on a silicon-on-insulator wafer using a complimentary metal-oxide-semiconductor-compatible process, and is subsequently bonded with the AlGaInAs QW structure using low temperature O/sub 2/ plasma-assisted wafer bonding. The optical mode in the SEL is predominantly confined in the passive silicon waveguide and evanescently couples into the III-V active region providing optical gain. The SEL lases continuous wave (CW) at 1568 nm with a threshold of 23 mW. The maximum temperature for CW operation is 60/spl deg/C. The maximum single-sided fiber-coupled CW output power at room temperature is 4.5 mW.     

A novel frequency offset estimation method for OFDM systems with large estimation range

In this paper, we proposed a novel frequency synchronization method which has larger estimation range than conventional method proposed by Tufvesson. A two steps frequency offset estimation method is performed in the new method. In the first step the received signal is correlated with local training sequence to eliminate the influence of training sequence which makes the estimation range of frequency offset is independent of period of the repeated data in the training sequence. The received signal is correlated with its delay in the second step to obtain the fine estimation of frequency offset. Precise estimation can be achieved in the proposed method than Tufvesson's method. The period of the repeated data in the training sequence determines the estimation range of the frequency offset in the conventional method, while in the new method they are irrelevant. Tens of subcarriers spacing can be estimated by the new method. The new method can be used in other cases as long as a known sequence is transmitted, which will introduce valuable flexibility in training sequence design. The validity of the algorithm is verified in AWGN channel and multipath fading channel.     

GARTEUR飞机模型的有限元分析及模态参数辨识

对GARTEUR飞机模型利用MSC Nastran软件进行有限元分析,得出模型的固有频率与振型等参数. 在实验数据的基础上,基于频率响应函数的有理分式模型,采用Forsythe正交多项式改善求解性态,自己编写模态参数辨识软件进一步分析该模型,比较两软件计算出来的结果来验证自编软件的有效性、实用性.     

飞机舱门在风载作用下的强度

利用MSC Nastran,MSC Adams,MSC Fatigue联合分析舱门在风载荷作用下的强度.用MSC Nastran生成舱门的柔性体(.MNF)文件与.op2文件;将柔性体导入MSC Adams中替换刚性体舱门,仿真并输出载荷时间历程(.DAC)文件;在MSC Fatigue中利用载荷时间历程(.DAC)文件与.op2文件进行疲劳强度分析,得到该舱门在该风载作用下的疲劳强度.     

基于支持向量机的压裂井层优选

压裂是油田重要的增产措施，合理选择压裂井层是一项十分复杂的工作。在对影响压裂效果的各种因素综合分析的基础上，提出了基于支持向量机技术的压裂效果预测方法。采用该方法，利用油田开发动、静态数据，构建了压裂井层优选的支持向量机模型，对大庆油田采油八厂样本进行处理，符合率达89％以上，并在不同数目学习样本的情况下同模糊神经网络作了比较，性能远优于模糊神经网络，可很好地克服过学习问题。