机床上加工椭圆的机构设计及原理

本文根据椭圆轨迹的形成原理，设计了两种应用于生产实践的机构，这些机构能克服“卡死”和“轨迹不精确”等缺点，并经过数学证明是确实可行的。     

乙烯砜活性染料同α－甲基－D－葡萄糖苷反应生成化合物碱解反应动力学的研究

利用高压液相色谱研究了乙烯砜活性染料同α－甲基－Ｄ－葡萄糖苷反应生成化合物Ｄ４，Ｄ６的碱解反应，结果发现：染料糖苷化合物Ｄ４，Ｄ６的碱解反应在初始阶段主要是消除反应；在ＰＨ值恒定条件下，低温时，化合物Ｄ６较Ｄ４碱解反应速度快，而在高温时，化合物Ｄ４较Ｄ６碱解反应速度快；两者的碱解反应均随温度升高而反应速度增快。     

A mechanism motion error sensitivity analysis method based on principal component analysis and artificial neural network

Present sensitivity analysis of motion error usually focuses on the trajectory deviation of the mechanism, which inevitably introduces an intractable time dependent problem. For efficiently and accurately measuring the motion error of the planar mechanism with dimension and clearance uncertainties by global sensitivity analysis (GSA), a novel method is proposed in this work. By applying the principal component analysis (PCA), the motion error is transformed into new vector output and cleverly avoids the time dependent problem. To ensure the accuracy of PCA in the case of small samples, the Bootstrap method is introduced. Based on the PCA results, the artificial neural network (ANN) surrogate model is established between the input variables and the vector output. Then the classical variance-based GSA method is applied to obtain the variable importance ranking for different PCs, and the synthesized GSA indices are introduced. Four representative examples are studied to demonstrate the versatility and effectiveness of the proposed method.     

High-efficiency adsorption of phosphate by Fe-Zr-La tri-metal oxide composite from aqueous media: Performance and mechanism

In this study, Fe-Zr-La tri-metal oxide (FZLO) composite was synthesized by co-precipitation method as new complex adsorbent for effective phosphate removal from aqueous media. The scanning electron microscopic study revealed that the adsorbent was of amorphous structure and consisted of the inhomogeneous aggregated nanoparticles with different sizes. Various influencing parameters such as pH values, initial concentration of phosphate ions, contact time, temperature and co-existing anions were studied to perform batch adsorption experiments. The experimental results demonstrated that the adsorption process was highly pH-dependent and obtained the maximum phosphate adsorption capacity of 101.0 mg g⁻¹ at pH = 6. The adsorption process occurred on surface of FZLO composite has been found to be mono-layered and chemisorption dominated in nature as the data fitted well to Langmuir isotherm as well as the pseudo-second-order kinetic model. The structure and properties of the adsorbent before and after adsorption using FT-IR, XRD and XPS techniques suggested that the adsorption mechanisms involved electrostatic attraction, complexation and ligand exchange. After the adsorption, the remained P concentration met the permissible limit by the Environmental Protection Agency. The Fe-Zr-La tri-metal oxide composite could be a promising adsorbent for phosphate removal from aqueous media.     

Photoelectrocatalytic degradation of phenol using a TiO<Subscript>2</Subscript>/Ni thin-film electrode

As a new type of photoelectrode, TiO₂/Ni thin-film electrode was prepared by dip-coating technique. The structural and surface morphology of electrode was examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). Effects of initial phenol concentration, pH value, number of film layers, voltage of electrical bias applied, variation of inorganic salt type and types of dissolved gas on the photoelectrocatalytic (PEC) degradation of phenol using ultraviolet (UV) illuminated TiO₂/Ni thin-film electrode were investigated. The mechanism of PEC degradation of phenol was also studied by analyzing reaction intermediates.     

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柴达木盆地东部气田是我国陆上第四大气田,产层属于第四系涩北组,储层岩主要为粉砂岩、泥质松砂,少量细砂岩。储层泥质含量高,成岩性差,胶结疏松。产量稍大就会引起气井出砂严重,地面设备、管线均受损,大大限制了气井产能的发挥。气层单层厚度薄,但总厚度大,气、水关系复杂。针对气田的储层特征,文章系统评价了气层“五敏”伤害的机理和程度;并对气层钻井、完井、射孔、修井 、生产等各个施工过程中的工艺技术特点,诊断出了气层所存在的潜在储层伤害类型和伤害机理,提出了预防气层伤害措施和建议。     

Strengthening Mechanisms in Multiwalled Carbon Nanotubes Reinforced Co–W Pulse Electrodeposited Coatings

Cobalt–tungsten coatings reinforced with multiwalled carbon nanotubes (MWCNTs) were prepared by pulse electrodeposition (PED) from citrate bath dispersed with MWCNTs. Effect of MWCNTs and electrodeposition technique, i.e., PED on the microstructure and properties of these coatings was evaluated. The results show that the incorporations of MWCNTs, substantially improve the hardness of the deposited coatings. PED produces Co–W/MWCNT coatings that are featured by small grain size, low surface roughness, and uniform distribution of MWCNTs in matrix, and consequently display higher hardness. Grain refinement, thermal mismatch, Orowan looping, and shear lag mechanisms have played substantial role in strengthening of the Co–W coatings reinforced with MWCNTs. Investigations suggest that shear lag mechanism has a pronounced role in strengthening these coatings.     

Investigation on the film-coating mechanism of alumina-coated rutile TiO2 and its dispersion stability

The alumina and alumina-coated rutile TiO₂ samples were synthesized by the chemical liquid deposition method under various pH values and aging temperature. The prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), ζ-potential as well as X-ray photoelectron spectroscopy (XPS). The relationship between pH values, the dispersion stability, crystalline types and microstructure of alumina-coated rutile TiO₂ samples were studied. It is indicated that the coating film exhibited amorphous hydrous alumina (at pH 3–7), boehmite (at pH 7–9) and bayerite (pH > 11), respectively. And the higher aging temperature was in favor of the elevation of boehmite content of coating film. As the boehmite content increased, the dispersion stability was gradually enhanced and the prepared sample exhibited optimum dispersion stability at pH 9 and aging temperature 200 °C, respectively. The increase of steric hindrance and electrostatic repulsion led to the promotion of dispersion stability via coating hydrous alumina film on the surface of rutile TiO₂. The detection of AlO and the significantly enhancement of AlOTi intensity confirmed that the film coating process should be main attributed to both chemical bonding and physical adsorption.     

Microstructural evolution of carbon fiber reinforced SiC-based matrix composites during laser ablation process

In this work, four different carbon fiber reinforced SiC-based matrix composites (C/SiC) were prepared, and microstructure evolution during laser ablation process was characterized. Laser irradiation provided a special high-temperature environment up to 3500 °C. For all four composites, different morphologies can be obtained in the transition region due to the oxidation of different matrices. While only needle-shaped carbon fiber and nanolayered carbon without any matrix remained in the central region, indicating that graphitization process occurred in the center, resulting from the high-temperature and low-oxygen environment in the laser process. Therefore, the laser ablation of C/SiC composites is controlled by chemical and physical erosion, and mainly by the physical erosion in the center.     

High strength and high creep resistant ZrB2/Al nanocomposites fabricated by ultrasonic-chemical in-situ reaction

In this study, the ZrB₂/Al nanocomposites were fabricated via in-situ reaction of the Al-K₂ZrF₆-KBF₄ system, assisted with ultrasonic vibration and spiral electromagnetic stirring. Microstructure, tensile property and creep behavior of the fabricated nanocomposites were further investigated. Microstructure observation showed that the ultrasonic vibration could prevent the fast growth as well as break the clusters of in-situ synthesized nanoparticles in melt, resulted in smaller size (10–50 nm) and relatively more uniform distribution of the in-situ nanoparticles located on the boundary of and/or inside the aluminum matrix grains in the final composites. The fabricated nanocomposites exhibited an enhancement in both strength and ductility, due to the elevated work hardening ability, i.e., improved dislocation propagating ability and decreased dynamic recovery of the existing dislocations induced by the in-situ nanoparticles. Meanwhile, the nanocomposites exhibited excellent creep resistance ability, which was about 2–18 times higher than those of the corresponding aluminum matrix. The stress exponent of 5 was identified for the fabricated nanocomposites, which suggested that their creep behavior was related to dislocation climb mechanism. The enhanced creep resistance of the nanocomposites was attributed to the Orowan strengthening and grain boundary strengthening induced by the ZrB₂ nanoparticles. Thus, the ultrasonic-chemical in-situ reaction promises a low cost but effective way to fabricate aluminum nanocomposites with high strength and high creep resistance.