On the Cure Acceleration of Oil-Phenol-Formaldehyde Resins with Different Catalysts

Oil-phenol-formaldehyde (Oil-PF) resins containing 50 wt% replacement of petroleum phenol with bio-oil were prepared and different catalysts [sodium carbonate (Na₂CO₃), urea, and magnesium oxide (MgO)] were added in the synthesis process of resins to accelerate the cure. The cure-acceleration effects of catalysts on cure characteristics of oil-PF resins were investigated by using differential scanning calorimetry (DSC), gel time, and a plywood panels test. The results indicated that catalysts presented different accelerating effects on the cure of the oil-PF resin. Both Na₂CO₃ and MgO can accelerate the oil-PF resin cure at a low temperature; however, urea seemed to have no significant effect on the cure of the resin. The application of Na₂CO₃- and MgO-accelerated oil-PF resins reduced hot pressing time for the manufacture of three-layer plywood panels. Compared with MgO, Na₂CO₃ had more significant accelerating effect on the cure of the oil-PF resin.     

氮气压缩机运行故障原因分析及对策

空分装置氮气压缩机驱动端振动值超标,严重影响装置安全平稳运行。通过分析振动值超标的原因,制定有效的修复措施,彻底解决设备故障。     

泄漏检测技术在生产应用中问题的探讨

介绍了生产过程中常用的几种泄漏检测方法,对影响泄漏试验的一些因素,诸如测试容积,温度,测试压力、稳定时间及封堵形式等进行了讨论。     

基于改进PSO算法的数控机床主轴优化设计

通过分析主轴结构和加工过程中受载变形情况, 建立了主轴优化设计的数学模型。根据邓克莱法计算得到的一阶固有频率近似值,引入动态约束条件 。针对传统优化设计方法在解决主轴优化设计中出现的问题,引入粒子群优化 (PSO) 算法,并提出了一种惯性权重值适应性递减的粒子群（ADW）算法。将ADW算法用于数控机床主轴优化实例中,得到主轴结构参数优化组合。研究结果表明,运用所建立的主轴优化设计数学模型及改进粒子群算法可以得到主轴结构参数优化组合,充分显示了该研究方法的有效性。     

中和方法对猪皮服装革质量的影响

通过组织学分析、物性检测等方法比较了猪皮服装革生产时用ＮＨ４ＨＣＯ３和中和复鞣剂中和对成革质量的影响。结果表明，用ＮＨ４ＨＣＯ３中和时，由于需要将革中和至较高的ｐＨ值（６．５左右）才能达到中和的目的，容易导致革纤维产生同部缺陷，从而降低成革质量。采用中和复鞣剂中和能明显减少同部缺陷，并使革纤维分散更均匀，成革的丰满弹性更好，松面率降低。本文选用萘磺酸型辅助性合成鞣剂ＮｅｏｓｙｎＢＳ２作为中和复鞣剂进行研究，确定了其最优使用方法。     

可控震源先进Ⅲ电控箱体常见故障分析及排除

在实际生产中，可控震源的故障很大一部分与其电控箱体有关，文章列举了几种因先进Ⅲ电控箱体而使I／O AHV—Ⅳ型可控震源出现的常见故障，分析了故障原因，并给出了排除方法。     

Frost formation on a bionic super‐hydrophobic surface under natural convection conditions

A bionic super‐hydrophobic surface has a multiple micro‐nano‐binary structure (MNBS) similar to the lotus leaf surface microstructure. This kind of surface has a contact angle of water greater than 150^° and a roll angle smaller than 5^°. In this paper, the frost deposition phenomena on a bionic super‐hydrophobic surface were observed. The surface has many micro bumps and its contact angle is 162^°. The formation of water droplets, the droplet freezing process, the formation of initial frost crystals and the frost layer structure on a cold bionic super‐hydrophobic surface under natural convection conditions were closely observed. The frost layer structure formed on the super‐hydrophobic surface shows remarkable differences to that on a plain copper surface: the structure is weaker, looser, thin, and easily removed and most importantly, it is of a very special pattern, a pattern similar to a chrysanthemum, a frost layer structure that has not been reported before to the best of the present authors knowledge. The experimental results also show that a super‐hydrophobic surface has a strong ability to restrain frost growth. The frost deposition on this bionic surface was delayed 55 minutes when compared with a plain copper surface under the conditions of a cold plate temperature of ?10.1^°C, air temperature of 18.4^°C, and relative humidity of 40%. A theoretical analysis was also presented to explain the observed phenomena. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(7): 412–420, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20216     

High-resolution cross-estimation channel modelling method and experimental results on broadband mobile communication in urban rich-scattering environment

For the IMT-advanced broadband mobile communication systems, an accurate broadband channel model is significant to the system design. However, the broadband channel impulse response (CIR) becomes sensitive to the complex propagation impacts of both specular path and diffuse dense path in a rich-scattering environment. We propose a cross-estimation (CE)-based channel modeling method by which the dense diffusion components can be identified independently and separated successfully from the overall CIR. As a result, the parameter estimation accuracy can be obviously improved, regardless of the complex diffusion impact in a rich scattering environment. Both theoretical derivation and experimental results are given to validate it based on the typical broadband channel measurement with 100 MHz bandwidth at 2.6 GHz in an urban hotspot scenario in Shanghai.     

放热型铁水预处理用高效复合脱硫剂的研究

为减少铁水炉外脱硫过程的温降,研制了一种含镁的复合脱硫剂。在150kg感应炉内模拟铁水罐喷吹脱硫的温度条件,试验了镁质脱硫剂的脱硫效果,并与取自生产现场的碳化钙基脱硫剂进行了脱硫效果与脱硫过程铁水温降的比较,为获得相同的脱硫效果,碳化钙基脱硫剂耗量为镁质脱硫剂的2倍、温降增加15℃。此外,探讨了铁水条件对镁利用率的影响。     

Study on Ti fiber reinforced TiAl<Subscript>3</Subscript> composite by infiltration-in situ reaction

This study is concerned with investigation of forming Ti fiber reinforced TiAl₃ composite by infiltration-in situ reaction. The as-cast material was obtained by pressing molten pure Al into a preform which was composed of Ti particles and Ti fibers. Based on the differential scanning calorimetry (DSC) result, in situ reaction samples were obtained by heating as-cast materials to 660, 950, and 1300 °C, and held for 1 h, respectively. The microstructure evolution of in situ reaction samples was analyzed by scanning electron microscope and Energy dispersive X-ray (EDX). In addition, the phase composition of products was inspected by X-ray diffraction (XRD). Experiment results show that TiAl₃ was formed initially, which was the unique product between Ti and Al. While at high temperature, products of Ti fibers and Al were complex, and Ti _x Al_1−x (0.25 < x < 0.75) compounds were formed around Ti fibers. Finally, TiAl₃ decomposed, and oxidation occurred. The mechanism of in situ reaction between Ti and Al in this system was discussed.