Comparison of the anti-coking performance of CVD TiN,TiO2 and TiC coatings for hydrocarbon fuel pyrolysis

Previous work has shown that both TiN and TiO₂ coatings can inhibit the metallic catalytic coking effectively, but both of them have their own shortage. In this work, TiC coating was prepared on the surface of SS304 tube using TiCl₄-CH₄-H₂ by CVD method. Its morphology, elemental composition, thickness and oxidation resistance were characterized by SEM, EDX, metalloscopy and TPO tests, respectively. The results show that CVD TiC coating is gray, homogeneous, and dense without cracks or holes. The TiC coating presents a cuboid particle structure with the sizes of about 1.0 µm for the cuboid crystals, and the Ti/C ratio close to 1:1, while the average thickness is about 11.62 µm. TPO results show that the TiC coating begins to react with O₂ and release CO₂ at about 810 °C. Compared with the TiN coating (The initial oxidation temperature of TiN is about 350 °C), the oxidation resistance of TiC coating is improved substantially. As a conclusion, the high oxidation resistance order is TiO₂ coating>TiC coating>TiN coating. Furthermore, the temperature programmed cracking of RP-3 Chinese jet fuel was employed to compare the anti-coking performance of TiN, TiO₂ and TiC coatings. The results show that each of TiN, TiO₂ and TiC coating has obvious anti-coking effect, and the anti-coking performance order is TiN coating=TiC coating>TiO₂ coating.     

Temperature-independent and enhanced dielectric properties for two-layer structure capacitors with 0.8Pb(Fe2/3W1/3)O3–0.2PbTiO3–MnO and 0.7Pb(Fe2/3W1/3)O3–0.3PbTiO3–MnO ceramics

This study fabricates capacitors with two-layer structure and different compositions, 0.8Pb(Fe_2/3W_1/3)O₃–0.2PbTiO₃–MnO and 0.7Pb(Fe_2/3W_1/3)O₃–0.3PbTiO₃–MnO, by using the conventional solid state oxide reaction method. By using the temperature compensation effect and adjusting the thickness ratio of the two layers with different compositions, the temperature–dielectric peak is enhanced and smoothed. The dielectric loss, space charge polarization and dc conduction are suppressed at the highest temperature region. Furthermore, the Maxwell–Wagner model is used to fit and explain the dielectric behaviors. This study also provides suggestions and discussion related to the effect of the interfacial region based on the experimental data and fitting results.     

人呼吸道合胞病毒的稳定性

目的观察人呼吸道合胞病毒(HRSV)在不同温度保存、冻融和超声波处理的稳定性。方法将HRSVA2株接种于KMB17细胞上适应培养后,收获病毒液,分别置于37、22、4和-20℃条件下保存不同时间,或经冻融和超声波处理后,用微量细胞病变法检测HRSV的感染性滴度,观察其稳定性。结果HRSV在37℃保存,病毒感染性滴度下降很快,第4天时,降至约1.50lgCCID50/ml,5d后降至1.00lgCCID50/ml以下,几乎检测不到;在22℃保存,病毒感染性滴度下降相对缓慢,第14天时比原始滴度降低约3.20lgCCID50/ml;在4℃和-20℃下保存较稳定,分别保存5周和3个月后,病毒感染性滴度下降<0.60lgCCID50/ml。冻融1、2、3次,病毒感染性滴度分别下降1.37、2.55和3.61lgCCID50/ml,冻融4次后,病毒几乎无感染性。超声波处理后,病毒感染性滴度下降很快,处理1次病毒滴度即下降至原始滴度的50%左右,处理2次后,病毒几乎无感染性。结论HRSV不宜在37℃和22℃存放,可短暂保存于4℃,在-20℃可保存较长时间;冻融和超声波处理均对病毒感染性滴度有明显影响。     

聚氨酯功能梯度材料的研究现状与展望

简介了聚合物梯度材料的发展概况,并着重综述了聚氨酯功能梯度材料的研究进展。     

COMPARISON OF VARIOUS CONJUGATE GRADIENT METHODS FOR INVERSE HEAT TRANSFER PROBLEMS

Many inverse heat transfer problems can be solved efficiently through the minimization of a performance function utilizing the conjugate gradient method. The gradient of the performance function needed in the minimization procedure of the conjugate gradient method is obtained by employing either the adjoint variable method or the direct differentiation method. In the present study we consider an inverse problem of estimating time-varying strength of a heat source in a two-dimensional heat conduction system, and compare the adjoint variable method and the direct differentiation method in terms of accuracy and computational efficiency, and finally suggest a new method that exploits the advantageous aspects of both methods while avoiding the shortcomings of them.     

长春岭含水原油流变性研究

利用RV22型粘度计,模拟地层条件下流体状态,对长春岭107区和109区3个油样进行了试验研究,测量了不同温度、不同含水率下含水原油粘度,了解原油的流变性,研究结果表明含水原油粘度随含水率变化存在极大值（非乳化拐点）。结论可为油田的开发及原油集输提供科学依据。     

具有梯度孔结构多孔陶瓷膜支撑体的制备

采用平均粒径为0.56μm的Al2O3为原料,研究了不同固相含量的Al2O3悬浮液的流变性能.在此基础上,采用含10%(质量分数,下同)Al2O3的悬浮液,通过重力沉降和真空抽吸过程,成功制备出具有梯度孔结构的片状Al2O3支撑体.对具有梯度孔结构支撑体的微观结构进行了表征,并研究了支撑体的孔隙率和渗透性能随烧成温度的...     

An FTIR/ATR in situ study of sorption and transport in corrosion protective organic coatings: Paper 2. The effects of temperature and isotopic dilution

A detailed temperature variation (18–50 °C) FTIR/ATR study of sorption and desorption of water into a series of cured epoxy resins has been reported. For higher temperatures (35–50 °C) the data were modelled with a single Fickian diffusion equation, giving an increased D as the temperature increased and an activation energy (E_A) in the 55–60 kJ mol⁻¹ region. At lower temperatures (18–35 °C)—well-below the T_g—a two-stage sorption equation was needed and the apparent E_A was negative. This is probably associated with changes in water clustering among the distributed ‘voids’ in the glassy polymer associated with chain relaxation at extended times. The use of D₂O as a penetrant allowed diffusion coefficient measurements for highly dense epoxy matrices, where FTIR/ATR cannot detect the ν(OH) band of water over and above the residual polymer–OH groups (in the dry state). The data for the D₂O studies were notably influenced by isotopic exchange; which was found to be a diffusion controlled process, even in a polymer matrix.     

级联形态梯度变换及其在继电保护中的应用

介绍了现在应用已较成熟的灰值腐蚀和灰值膨胀运算,由此引出多分辨形态学梯度变换(MMG)的定义;进而在其基础上提出了一种新型的级联多分辨形态梯度变换(SMMG)的概念,SMMG具有很强的奇异信号检测和波形识别能力,作为一种特征提取工具,SMMG能感受并增强信号波形上的微小变化、反映突变的大小.和其它形态学算子一样,它具有SMMG具有表达直观、滤波器设计简单、数据窗短、计算速度快以及变换结果易于识别、对硬件没有过高的要求等优点,因此在继电保护的信号处理中具有良好的应用潜力和实用价值,在现有的微机保护装置中可以直接采用.文中最后给出了其在电力系统继电保护中应用的2个实例,EMTP仿真研究表明:文中提出的相继速动判据具有更高的灵敏度;所提出的基于SMMG的微机线路保护的选相元件能在8ms内正确地识别几乎所有故障情况的故障相别.由SMMG构成的保护元件灵敏度很高,在电力系统高速及超高速保护方面有良好的应用前景及较大的实用价值.     

大型水轮发电机通风发热场模型研究及通风结构优化计算

将大型水轮发电机的转子三维温度场与电机整体通风网络联系起来,形成通风发热综合计算过程,旨在准确地得到部件中的温度及其分布。并利用优化技术调整结构尺寸,使各部件中温度分布趋于均匀。本文的研究工作对于提高电机设计制造中材料利用率以及电机运行中的可靠性,具有重要意义。