汽车发动机润滑油劣化规律的试验研究

应用理化性能指标快速检测法和铁谱分析法，对在用车润滑油每隔一定里程抽取油样，检测了其含水量、酸值、闪点、燃点以及铁屑浓度等指标，研究了在用车润滑油的劣化规律。结果表明，随着行车里程的增加，在用发动机油的含水量和酸值增高，闪点和燃点降低，铁屑浓度缓慢增加；应用润滑油理化性能指标快速检测法，能够定量地评价发动机润滑油品质的变化程度，实现按质换油，应用铁谱分析法对发动机的状态进行监测，能够定量地评价发动机机件的磨损程度，实现发动机视情维修。     

简形件强力旋压发展过程及其现状分析

通过对筒形件强力旋压发展过程的回顾和国内外技术现状的分析。进一步加深了对该加工工艺的了解并探寻新的发展方向。目前．普通简彤件强力旋压工艺已经相当成熟，而带有纵向内筋的筒形件强力旋压工艺还相对落后。因此，进一步深入开展带内筋筒形件强力旋压工艺成形机理和变形特点的研究，有着重要的理论意义和实际应用价值。     

Monodisperse hollow TiO2 spheres for thermal insulation materials: Template-free synthesis,characterization and properties

Hollow TiO₂ spheres were easily fabricated through a template-free solvothermal route only using tetrabutyl titanate (TBT) as raw material and absolute ethanol as solvent. The morphology of hollow TiO₂ spheres was successfully controlled by adjusting the reaction time and reaction temperature. The formation process of hollow TiO₂ spheres includes three steps based on the experimental results: the hydrolysis of TBT to produce Ti(OH)₄ clusters in water formed from an ethanol etherification reaction under high temperature and high pressure, the assembly of Ti(OH)₄ clusters into solid spheres, and the transformation of solid TiO₂ spheres into hollow TiO₂ spheres. Furthermore, the as-prepared hollow TiO₂ spheres exhibited good thermal insulation performance including heat barrier and heat reflection.     

Manganese-rich SmBaCo2−x−yMnxMgyO5+δ (x = 0.5, 1, 1.5 and y = 0.05, 0.1) with stable structure and low thermal expansion coefficient as cathode materials for IT-SOFCs

SmBaCo_2−x−yMn_xMg_yO_5+δ (x = 0.5, 1, 1.5 and y = 0.05, 0.1) samples are synthesized by sol-gel method. The influence of different substitution of Mn and Mg for Co on crystal structures, thermal expansion coefficient (TEC), electrical conductivities and electrochemical performances have been investigated. The generation of the secondary phase BaMnO₃ is suppressed with Mg²⁺ increasing. Demonstrated by temperature-dependent X-ray diffraction from 25 °C to 700 °C, the structure of SmBaCo_0.4Mn_1.5Mg_0.1O_5+δ in high temperature is stable. The TEC of SmBaCo_1.45Mn_0.5Mg_0.05O_5+δ, SmBaCo_0.95MnMg_0.05O_5+δ, SmBaCo_0.45Mn_1.5Mg_0.05O_5+δ and SmBaCo_0.4Mn_1.5Mg_0.1O_5+δ are 15.77 × 10⁻⁶ K⁻¹, 16.20 × 10⁻⁶ K⁻¹, 12.19 × 10⁻⁶ K⁻¹ and 12.58 × 10⁻⁶ K⁻¹, respectively, which are much lower than those of cobalt-based layered perovskites and more compatible with the thermal expansion of SDC electrolyte. Although the electrochemical performances of SmBaCo_2−x−yMn_xMg_yO_5+δ (x = 0.5, 1, 1.5 and y = 0.05, 0.1) decrease slightly with Mn increasing, the polarization resistances of the SmBaCo_1.45Mn_0.5Mg_0.05O_5+δ and SmBaCo_0.4Mn_1.5Mg_0.1O_5+δ are 0.17 Ω cm² and 0.30 Ω cm² at 800 °C, respectively, which can meet the electrochemical performance requirements of cathode materials. Among the samples, the SmBaCo_1.45Mn_0.5Mg_0.05O_5+δ and SmBaCo_0.4Mn_1.5Mg_0.1O_5+δ show better tradeoff properties between TEC and electrochemical performance as cathode materials for IT-SOFCs.     

A novel synthesis route of titanium dioxide with (NH4)0.3TiO1.1F2.1 as by-product

This work explores a new route for the synthesis of titanium dioxide using scraps and titanium chips, which are typically discarded as waste, as the precursor materials. The band-gap energy of the synthesised materials was determined using diffuse reflectance spectroscopy. The morphology, elemental analysis, crystallinity, and chemical structure of the synthesised materials were determined by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, and infrared and Raman spectroscopies, respectively. The X-ray and Raman analyses confirmed the formation of titanium dioxide in its tetragonal (anatase) crystalline form after heat treatment (400 °C, 2 h). Moreover, a mixture of (NH₄)_0,3TiO_1,1F_2,1 and anatase TiO₂ was obtained as a by-product. After heat treatment, this by-product was converted into fluorine-doped titanium dioxide, also in anatase crystalline form. The apparent crystallite size (L_c) of anhydrous titanium dioxide was found to be smaller than that of the calcined by-product. The diffuse reflectance spectroscopy analysis revealed that the calcined by-product has a significantly higher absorption capacity at higher wavelengths, as well as a lower band-gap energy value. The scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) analyses showed large particulates on which smaller particles are deposited and good dispersion of the elemental components. The anhydrous titanium dioxide sample presents a smaller particle size than the calcined by-product.     

High-performance and low-voltage SnO2-based varistors

This paper presents the results of a thorough study conducted on the action mechanism of one-dimensional single-crystalline SnO₂ nanobelts in decreasing the breakdown electric field (E_b) in SnO₂-based varistors. The proposed method has general validity in that our investigation was focused on the traditional varistor composition SnO₂-CoO-Cr₂O₃-Nb₂O₅. To accomplish our study objective, two methods of decreasing E_b value were compared; one involving the increase in average grain size of the varistor through the sintering time and the other one related to the addition of nanobelts. The morphological results show that the method involving the increase in average grain size is limited by the formation of intragranular pores. Furthermore, despite contributing successfully towards decreasing the E_b value (which underwent a decline from 3990 V cm⁻¹ to 1133 V cm⁻¹ with an increase in sintering time from 1 h to 2 h), the reduction obtained by this method is found to be much lower compared to that obtained via the nanobelts insertion method (E_b = 270 V cm⁻¹). Impedance spectroscopy results showed that the insertion of nanobelts caused a decline in the grain boundary resistance while surface potential measurements proved that this decline in resistance is attributed to the absence of potential barriers along the belts which leads to the formation of a lower resistance percolation path in the varistor.     

RBAC模型时间约束的OCL描述

基于角色的访问控制模型以其灵活性、方便性和安全性在许多系统的权限管理中得到普遍应用,而引入时间约束后的角色访问控制更能增强系统的安全性和模型的描述能力。该文使用对象约束语言OCL来描述模型中的时间约束,使模型更加直观和精确。     

基于蕴涵算子族Lλ0λG的反向α-三I支持算法

提出了基于蕴涵算子族Lλ0λG的模糊推理的思想,这将有助于提高推理结果的可靠性。针对蕴涵算子族Lλ0λG给出了模糊推理的FMP模型及FMT模型的反向α-三I支持算法。     

基于蕴涵算子族L-λ-G的反向三I约束算法

提出了基于蕴涵算子族L-λ-G的模糊推理的思想,这将有助于提高推理结果的可靠性。针对蕴涵算子族L-λ-G给出了模糊推理的FMP模型及FMT模型的反向三I约束算法、α-反向三I约束算法。