In this work, the rutile mesocrystals TiO₂ were synthesized by hydrothermal method using layered titanate HTO (H_4x/3Ti_2-x/3□ _x/3O₄?nH₂O) as the precursor. By means of X?ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other testing methods, the effect of reaction temperature on the synthesis of rutile?type mesoscopic TiO₂ crystal material by means of topological structure transformation was studied. The results reveal that rutile TiO₂ can be obtained under the condition of pH 0.5 of the reaction system, and with the gradual increase of the reaction temperature, the rutile?type mesoscopic TiO₂ crystal material is formed at 120 ℃. Taking Rhodamine B (RhB) as the pollutant model for degradation experiments, the photocatalytic activity of rutile mesocrystals TiO₂ is significantly higher than that of other samples. Experiments on dye?sensitized solar cells (DSSCs) show that the mesocrystals structure formed at 120 ℃ is conducive to the rapid migration of photogenerated carriers, thus obtaining high cell characteristics.

Oil and gas pipelines (X52 steel) in the marine environment are highly susceptible to corrosion. The effects of different dissolved oxygen concentration, pH, and hydrostatic pressure on the corrosion behavior of X52 pipeline steel in the marine environment was analyzed using electrochemical testing technology and observation of corrosion morphology. The results show that the corrosion of the pipeline slowed down as the ambient pH increased, while the corrosion of the pipeline steel increased as the dissolved oxygen content and hydrostatic pressure increased. The corrosion behavior of pipeline steel under different conditions is controlled by anodic activation of dissolution, and all appear local pitting corrosion phenomenon.

The problem of H∞ output tracking control for switched time⁃delay systems is investigated by using mode⁃dependent average dwell time method. Using the multiple Lyapunov function method, the condition satisfied by the mode⁃dependent average dwell time was developed, such that the considered systems were exponentially stabilizable with H∞ output tracking performance, the switching controller combining state feedback and tracking error integral was also designed simultaneously. Different from the single average dwell time method, the mode⁃dependent average dwell time method allowed each subsystem of switched systems to possess its own average dwell time, thus it reduced the conservatism of the results. Finally, a numerical example was used to illustrate the effectiveness of the proposed theoretical results.

The spindle is the core part of the high speed milling machine, its dynamic characteristics directly affect the machining accuracy of the milling machine.Taking a German GMN high⁃speed milling machine electric spindle as an example, the finite element method was used to establish a finite element model of the spindle⁃bearing system, the natural vibration characteristics of the spindle were studied, and the influence of bearing stiffness on the natural vibration mode and critical speed of the spindle was analyzed.On this basis, the unbalanced response characteristics of the high⁃speed spindle were studied, and the influence of the unbalance amount and position on the vibration sensitivity of the spindle was analyzed. It was found that the unbalanced response at both ends of the spindle was sensitive, especially at the end where the tool was connected. The results could provide a certain reference for the dynamic design of the high⁃speed machine tool spindle system.

In solvent⁃free condition, a new 1D chain holmium phosphite Ho(H2PO3)4(C6N2H16)0.5 (compound 1) decorated by phosphite groups has been synthesized using N,N'⁃Dimethylpiperazine (Me2ppz) as structure directing agent, and further been characterized by powder XRD, infrared spectroscopy, thermogravimetric, inductively coupled plasma and CHN elemental analyses. Single crystal X⁃ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic crystal system with the P21/c space group. The structure of compound 1 is constructed by HoO6 octahedra and [H2PO3]- pseudo⁃pyramids units via vertex oxygen atoms. It is worth noting that compound 1 is the first rare earth phosphite compound which is synthesized in solvent⁃free condition. Moreover, a pair of left⁃ and righ⁃handed helical chains are present in the structure. In addition, coordination mode and geometry of lanthanide phosphonate, phosphate and phosphite are listed in this paper.

In recent years, high sulfur and high acid crude oil is widely used in refining device. The sulfur and acid substances in crude oil are extremely corrosive, causing huge security risks to the normal operation of equipment. In this paper, the ultrasonic thickness measurement, macroscopic examination and other means of a set of atmospheric and vacuum unit conducted a comprehensive corrosion inspection. Combined with the scene photographs of the corrosion morphology of gray scale analysis, corrosion scale samples for component analysis can accurately and clearly understand the influencing factors of corrosion occurrence and development. The corrosion rate and the remaining service life of the device in the corresponding position are calculated with the monitoring data of the site. Combined with the operation cycle of the device, the conclusions and suggestions related to corrosion protection are put forward.

The geometric models and finite element models of triscrew extruder with different rotors have been established, and the models have been simulated by Polyflow. The mixing index, shear rate, logarithm of stretching, instantaneous efficiency, the average time efficiency and other evaluation parameters have been calculated using particle tracking method. The results show that, the number of shear and stretching in triscrew extruder in the same period increase with the increase of screw head numbers. Accordingly, the mixing effect is also increased gradually.

To solve the overlap of part of fault classes in the analog circuit fault diagnostics, a novel analog circuit fault diagnostics approach based on quantum neural networks algorithm was presented. Kurtosis and entropy were calculated as features after the time domain response signals of the circuit under test were measured, and then the different fault classes were identified by quantum neural networks algorithm. The simulation demonstrated that constructed neural network had simple network structure and the fault diagnosis accuracy was higher, which reached 99.62%.

The direct cause of gathering pipe network failure was the failure of the pipeline and accessories equipments according to a lot of field investigation .The fault tree was established as the top event of gathering pipeline failure on the basis of the comprehensive analysis of gathering pipeline network failure factors. Considering about the 44 basic events, the descending method was used to analyze the gathering pipeline network failure fault tree, and obtained all 52 minimum cut sets in the system. And the quantitative analysis of the fault tree was carried on. The qualitative analysis was carried on the gathering pipe network and the weakest link was found out in gathering pipe network, which could maintenance the old pipeline network and provide theoretical guidance for the design of the new pipeline network.

Based on nonlinear dynamic properties, the dynamic model of two-span sliding bear-rotor with coupling nonlinear oil and rubbing force were studied by means of numerical stimulation. The effect of oil and rubbing force on bifurcation and chaos behaviors is analyzed. Abundant dynamic behaviors of rotor were revealed by the diagrams displaying bifurcation and chaos behaviors, such as Poincaré mapping, bifurcation diagram, phase plane plots, locus trajectory, as well as amplitude spectrum. The results show that the system of bearing-rotor with nonlinear impact/rub and oil film force has abundant nolinear dynamic behaviors.