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A series of the experiments were carried out on the Nandan lead-zinc tailings management and one bioleaching method was proposed with the purpose of recovering the valuable metal such as Zn. Firstly, multi-elements analysis was performed to provide theoretical data. Secondly, the effect of the pH on the bacterial growth and Fe²⁺ oxidation was investigated. The results showed that pH at 2.5 was the optimum for the bacteria. The concentration of the bacteria at pH 2.5 can be up to 9.3×10⁷ cells/mL. Finally, the bioleaching treatment was performed to study the potential of bioleaching the tailings. The data illustrated that the method of bioleaching can extremely recover metals such as zinc from the tailings, which provided novel insights into metal recycling.

A novel robust control scheme for decentralized generator excitation and valve coordinated control systems to improve power system stability is proposed. By utilizing generator terminal voltage magnitude and phase angle to represent the interactions among generators, decentralized generator excitation and valve coordinated control in multi-machine power systems is achieved. The control is realized by robust parametric approach. Simulation results show that the proposed robust parametric coordinated control can improve power system stability.

This study was a continuation of previous work designed to further explore the effect of different culture condition on the recovery of the valuable metals by bacteria. The experiment focused on the Nandan lead-zinc tailings from different depths. First of all, the study systematically performed multi-elements analysis. Subsequently, the effect of the temperature and agitation speed on the bacterial growth was investigated. The data revealed that the temperature of 35°C and the agitation of 160 rpm were the optimum culture conditions for the bacteria. Finally, the bioleaching experiments were performed to explore the ability of bioleaching the tailings. The study illustrated that the microorganism was able to effectively extract valuable metals from different depths samples.

The inertial friction welding of similar PM FGH96 superalloy was investigated. The inertial friction welding introduced steep thermal gradients of welding zone for PM FGH96 superalloy, the whole welding process only needed several seconds, therefore, it’s a fast heating and cooling completely recrystallization process. Dramatic changes in the microstructure were observed over a narrow weld zone, which across the weld interface was measured to be about 1.0-1.2mm. Significant changes in the secondary and tertiary γ′ distribution can be observed over the first 2mm from welding line, while very fine tertiary γ′ particles precipitated in a unimodal size distribution and in a high density at welding line. The fine secondary re-precipitated γ′ under fast cooling was spherical in shape, which gradually transformed into elliptical, cube with the distance from welding line. No significant texture or grain distortion was observed in the extensively plastically deformed region due to recrystallization.

Power flow shift being one of the main reasons that cause a large-scale blackout of power system, it is important to get the power flow shift under control at the beginning of the failure. In view of multidrop overload which frequently occurs in power outage, a comprehensive evaluation method is proposed to control the power flow shift. This method synthetically considers the control nodes' ability to eliminate the overload of the transmission in combination with PCA in which nodes' sensitivity of branch is selected as the evaluation index, divides them into two types (nodes that increase the power output to branch and others that decrease the power output to branch) and then obtains the control nodes' operation sequence. Additionally, a reverse equal matching adjustment is used to realize the control over multidrop overload. Typical numerical example is used to verify the effectiveness of the comprehensive evaluation method.

A series of porphyrin sensitizers with different central metal ions (PMn, PFe, PCo, PNi, PCu, and PZn) have been studied based on density functional theory (DFT). The geometric structure of the dyes was optimized and the frontier molecular orbital were calculated. The result shows that the LUMO levels of PFe, PNi and PZn were much lower than that of PMn, PCo and PCu, which suggest a lower energy barrier for electron transfer from the donor to the acceptor tunneling. Furthermore, the energy gap of HOMO and LUMO for PFe was only 0.81 eV, it indicates a significant red shift of the absorption spectrum. The LUMO of PMn, PNi, PCu and PZn were mainly decocalized on the porphyrin core and the bridge moiety, which was beneficial to electronic transport.

In aerospace engineering, seal is an important component of manned spacecraft life-support system. The pressurized tube sealing equipment is designed, and the experimental system of principle leak-rate of pressurized tube is built, and the experimental theory of the principle leak-rate of pressurized tube is carried out. The experimental results show that leak-rate of pressurized tube is related with the internal pressure of pressurized tube, and sealing ability can be adjusted by controlling the pressure in tube. And leak-rate of pressurized tube is involved with sealed pressure differential, and the bigger pressure differential is, the larger leak-rate becomes. And pressurized tube can fit for big structure transfiguration, which provides condition for lessening structural weight. And the pressurized tube can meet the demands of sealing of space station.

In order to improve the plasticity of the Al–Mg alloy, which fabricated by continuous casting and rolling, the alloy was heat treated at 370 °C, 400 °C, 430 °C and 460 °C for 2 hours and cooled with the furnace. The microstructure and mechanical properties of heat-treated Al–Mg alloy under different heat treatment temperatures were analyzed. The results show that the columnar grains begin to disappear at heat treatment temperature of 460 °C. The size of equiaxed grains begins to increase as the heat treatment temperature increases. The tensile strength of the alloy decreases with the increase of heat treatment temperature and the Brinell hardness increases when the heat treatment temperature is between 370-430 °C. At heat treatment of 430 °C, the elongation and the Brinell hardness of the alloy reached to 42.91% and 70.5 HB, respectively.

Electroplating was employed to prepare Cu films on Fe substrates and Ni substrates. The average internal stresses in Cu films were measured in situ by cantilever beam test. The distribution of the internal stresses in Cu films was investigated. The results show that the average internal stresses and the distributed internal stresses in Cu films decrease abruptly with the increase of film thickness when the films are thinner. The interfacial stresses in Cu films are very large and growth stresses are very small. The average internal stresses in Cu films, which were caused by the adjustment of the electron densities at either side of the interface, were calculated roughly using a modified Thomas–Feimi–Dirac electron theory. For the same substrate and the same film, the theoretical value of the average internal stress in film is about equal to the experimental value. It shows that the theoretical calculation model of internal stress is of accuracy.

Linear defect is a common defect of galvanized sheet. Formation mechanism of linear defect was analyzed by scanning electron microscopy (SEM) and energy disperses spectroscopy (EDS). The results indicate that Al2O3 particles which have a size less than 7μm are enriched in the shallow surface of the substrate. Al2O3 particles are exposed during rolling, resulting in scratches and rough spots on cold-rolled sheet. The places where Al2O3 inclusions enrich are easy to form surface micro-cracks. Linear defects are formed at the places of scratches or cracks during hot dip galvanizing. Optimum measures are putted forward based on Al2O3 inclusions and cracks.