不锈钢上激光熔敷涂层结构特征与质量研究

采用5kW连续CO2激光器对经等离子喷涂的NiCoCrAlY结合层和ZrO2陶瓷层进行二次重熔处理，并利用金相显微镜、扫描电镜、电子探针和显微硬度计对激光熔敷涂层进行了显微结构、元素分布以及显微硬度观察与测试，结果表明：多道搭接工艺能降低熔敷涂层气孔率，ZrO2陶瓷层稀释度低，与基体结合完好，并观察到NiCoCrAlY合金层中存在明显的对流图案，加入了TiO2-Al-Ti添加剂的ZrO2陶瓷层激光重熔后得到了无裂纹的定向生长柱状晶，并且呈现一次枝晶平均间距为2．3μm的表层和平均间距为3．8μm的次表层结构。     

铬盐清洁生产工艺中铝的脱除

分析了K2Cr2O7清洁生产工艺中Al(Ⅲ）-K2CrO4-K2Cr2O7-H2O体系的离子平衡，推导出25℃时混合溶液中[Al(Ⅲ）]和[H^ ],[Cr2O7^2-]/[CrO4^2-]之间的对应关系。并由实验测定验证了这一关系。提出了通过调整K2CrO4碳酸化反应转化率来降低体系中Al(Ⅲ）杂质含量的新方法。工业试验已证明了其可行性。     

高聚合度β-萘磺酸盐缩合物的合成

介绍了用工业萘、硫酸、甲醛为原料，合成高聚合度β-萘磺酸盐甲醛缩合物的工艺过程。试验了不同的萘与甲醛配比、反应时间和催化剂对缩合物核体数的影响，确定了可行的工艺条件。     

Bayesian bounds for matched-field parameter estimation

Matched-field methods concern estimation of source locations and/or ocean environmental parameters by exploiting full wave modeling of acoustic waveguide propagation. Because of the nonlinear parameter-dependence of the signal field, the estimate is subject to ambiguities and the sidelobe contribution often dominates the estimation error below a threshold signal-to-noise ratio (SNR). To study the matched-field performance, three Bayesian lower bounds on mean-square error are developed: the Bayesian Crame/spl acute/r-Rao bound (BCRB), the Weiss-Weinstein bound (WWB), and the Ziv-Zakai bound (ZZB). Particularly, for a multiple-frequency, multiple-snapshot random signal model, a closed-form minimum probability of error associated with the likelihood ratio test is derived, which facilitates error analysis in a wide scope of applications. Analysis and example simulations demonstrate that 1) unlike the local CRB, the BCRB is not achieved by the maximum likelihood estimate (MLE) even at high SNR if the local performance is not uniform across the prior parameter space; 2) the ZZB gives the closest MLE performance prediction at most SNR levels of practical interest; 3) the ZZB can also be used to determine the necessary number of independent snapshots achieving the asymptotic performance of the MLE at a given SNR; 4) incoherent frequency averaging, which is a popular multitone processing approach, reduces the peak sidelobe error but may not improve the overall performance due to the increased ambiguity baseline; and finally, 5) effects of adding additional parameters (e.g., environmental uncertainty) can be well predicted from the parameter coupling.     

Relating the Morphology of Poly(p‐phenylene vinylene)/Methanofullerene Blends to Solar‐Cell Performance

The performance of bulk‐heterojunction solar cells based on a phase‐separated mixture of donor and acceptor materials is known to be critically dependent on the morphology of the active layer. Here we use a combination of techniques to resolve the morphology of spin cast films of poly(p‐phenylene vinylene)/methanofullerene blends in three dimensions on a nanometer scale and relate the results to the performance of the corresponding solar cells. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and depth profiling using dynamic time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) clearly show that for the two materials used in this study, 1‐(3‐methoxycarbonyl)propyl‐1‐phenyl‐[6,6]‐methanofullerene (PCBM) and poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene vinylene] (MDMO‐PPV), phase separation is not observed up to 50 wt.‐% PCBM. Nanoscale phase separation throughout the film sets in for concentrations of more than 67 wt.‐% PCBM, to give domains of rather pure PCBM in a homogenous matrix of 50:50 wt.‐% MDMO‐PPV/PCBM. Electrical characterization, under illumination and in the dark, of the corresponding photovoltaic devices revealed a strong increase of power conversion efficiency when the phase‐separated network develops, with a sharp increase of the photocurrent and fill factor between 50 and 67 wt.‐% PCBM. As the phase separation sets in, enhanced electron transport and a reduction of bimolecular charge recombination provide the conditions for improved performance. The results are interpreted in terms of a model that proposes a hierarchical build up of two cooperative interpenetrating networks at different length scales.     

Insulating safety analysis of the hot-line sweeping robot

This paper presents a method of calculating the insulating safety distances for hot-line working robots at high voltage when dielectric is adulterated with conducts. Also, finite element method is adopted to calculate the electric field strength to find whether it is beyond the critical. The above methods have been applied to analyze the insulating safety of the robot for hot-line sweeping post insulators in a 220 KV substation. They have also been testified by experimentations.     

建好社区平台促进就业发展

2002年全国再就业会议上提出来一个新名词社区平台,社区平台是社会保障体系建设的重要组成部分,建好社区平台,对促进就业、稳定社会将发挥很大的作用.     

Nickel and chromium cycles: Stocks and flows project part IV

Nickel and chromium are essential ingredients in alloys increasingly important for energy-efficient, environmentally friendly modern technology. Quantitative assessment of the flows of these metals through the world economy from resource extraction to final disposal informs resource policy, energy planning, environmental science, and waste management. This article summarizes the worldwide technological cycles of nickel and chromium in 2000. Stainless steel is the major use of these metals, but they serve numerous other special needs, as in superalloys for high-temperature service, as plating materials, and in coinage. Because they are used primarily in alloys, novel recycling issues arise as their use becomes more widespread. “... the great New York and St. Louis double track, nickel plated railroad...” — Norwalk, Ohio, Chronicle 10 March 1881 announces arrival of surveyors for the future Nickel Plate Railway “Later [1911] I formed an alloy of Iron and Chromium, which showed remarkable resistance to rust and tarnish ... [It was] rediscovered by an Englishman named Brearley, in 1914.” —Elwood Haynes to Stephen F. Roberts, 17 January 1925     

Influence of the silicon surface treatment by plasma etching and scratching on the nucleation of diamond grown in HFCVD - a comparative study

A comparative study for the nucleation of diamond was carried out using surface treatment like (i) surface scratching with 1 μm diamond paste and (ii) surface etching using chlorine plasma at different RF powers (50, 100 and 150 W). Atomic force microscopic study shows variation in roughness from 31 nm to 110 nm. Scratching results in random scratches, whereas plasma etches a surface uniformly. Scanning electron microscopic observations show well faceted crystallites with a predominance of angular shaped grains corresponding to 〈100〉 and 〈110〉 crystallite surfaces for the scratched as well as plasma etched substrate. Surface etching at 150 W plasma power results in a better growth in comparison with 50 and 100 W plasma powers. Chlorine-radical is found responsible for the changes in the growth morphology. Raman spectroscopy shows a sharp peak at 1,332 cm⁻¹ and a peak at ∼1,580 cm⁻¹ for both samples.     

Electromagnetic properties of ferroelectric-ferrite ceramic composites

The NiFe₂O₄ and Pb(Zr_0.52Ti_0.48)O₃ ceramic composites are prepared by conventional solid state reaction method. The microstructural and morphological properties of the composites are studied by X-ray diffraction analysis and scanning electron microscopy. Results indicate that the ferrite and piezoelectric phases can co-exist in the composites. The relationship between the dielectric constant and frequency (40 Hz–40 MHz) as well as temperature is also investigated. It is noted that the transition temperature of the composites is about 380 °C. A double electric hysteresis loop is observed in our composites. The magnetic properties are relatively weak according to the magnetic hysteresis loop. With increase in the content of the ferrite phase, the permeability increases. The electromagnetic properties of the as-prepared composites are tunable according to the content of the NiFe₂O₄ phase.