This paper summarized the separation effects of different electrodialysis systems on lithium in Salt Lake, including single selective electrodialysis, ionic liquid membrane and bipolar membrane, among which ionic liquid membrane with a broad development prospect possesses the characteristics of high recognition of Li+, long?term stability under electrolysis and low energy consumption. Furthermore, the advantages, disadvantages and tendency of prospective development of different electrodialysis systems in lithium extraction from Salt Lake were analyzed, and the industrialization research on the application of electrodialysis systems for lithium extraction from Salt Lake was analyzed.
Shale hydration and dispersion lead to instability of the borehole wall, which has always been a problem in oil and gas drilling engineering. Physically plugging pores and micro?cracks in shale through nano plugging agents is the best way to improve the stability of shale formations. In this work, the silane coupling agent KH560 was used to modify the high?concentration silica sol. The principle of soap?free emulsion polymerization was used in combination with solvothermal synthesis to graft acrylic acid (AA) and styrene (St) monomers on the surface of modified SiO2 particles. Thus, a new type of elastic pressure?bearing plugging agent with polymer?encapsulated nanoparticles was successfully developed. Taking medium pressure filter loss as the evaluation index, the best synthesis conditions were obtained: The reaction temperature was 60 ℃, the reaction time was 3.0 h, the monomer ratio was 3∶2, the pre?emulsification time was 10.0 min, the total monomer mass was 6.67%, and the amount of initiator was 0.40%. In addition, Zeta potential, particle size analyzer and transmission electron microscope proved that the median particle size of the prepared STA?1 plugging agent was 45.3 nm. Finally, a core displacement experiment was used to simulate the shale layer to investigate the actual plugging effect of STA?1. The results revealed that 1.00% STA?1 showed good water plugging ability for sand filled pipes with permeability below 2 000 mD, and the plugging rate was higher than 85%.
Iridium (III) complexes have broad application prospects in luminescence detection of analyte due to advantages of large Stokes shift, high quantum yields, long luminescence lifetimes, flexible and adjustable emission spectra, and excellent optical and thermal stability. The novel iridium(III) complex Ir(ppyTPA)3 was prepared by introducing triphenylamine substituent on 2?phenylpyridine, and the structure, luminescence and electrochemical properties of Ir(ppyTPA)3 were characterized in detail. Then, the luminescence properties of Ir(ppyTPA)3 were used to detect five common nitroaromatics and the detection mechanism was studied. The results show that Ir(ppyTPA)3 has the highest detection efficiency to 3?nitrobenzoic acid with the detection efficiency constant KSV of 19.78 L/mmol. And the detection limit is as low as 2.89×10-3 mol/L. Spectral analysis and density functional theory calculations show that the detection mechanism of Ir(ppyTPA)3 for the five nitroarenes was the charge transfer mechanism.
Solid oxide fuel cells (SOFC) as one of the energy conversion devices, have received widespread attention and importance from all walks of life because of its clean and efficient operation. Anode is an important part of SOFC. It is important to find anode materials with good fuel catalytic activity in SOFC field. In recent years, molybdat?based perovskite materials as SOFC anodes show excellent conductivity and electrochemical properties at low and medium temperatures, and have been extensively studied by many research groups. In this paper, the research progress of molybdate?base perovskite as SOFC anode is reviewed, and the effects of different doping conditions on the properties of materials are summarized from the theoretical and experimental results, so as to provide guidance for the future research of materials.
In this work, the rutile mesocrystals TiO2 were synthesized by hydrothermal method using layered titanate HTO (H4x/3Ti2-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.
As a universal low temperature gathering and transportation boundary condition,the wall sticking occurrence temperature (WSOT) has been widely promoted and applied in the oilfield in the late stage of high water cut development. When the oil gathering temperature is higher than the WSOT, the pipeline operates smoothly, otherwise the pressure drop of most pipelines increases significantly, but some of the pipeline pressure drop changes are not obvious. Through the field cooling experiment, it was found that in the process of the oil gathering temperature gradually decreasing to 6,8,10 ℃ and 12 ℃ below the gel point, the wellhead back pressure has experienced four stages of smooth operation, small fluctuation, low frequency large fluctuation and high frequency large fluctuation, and there are several "restart" processes in the pipeline when the gathering temperature is too low. At the same time, the gas injection experiment under different gas?oil ratio was further carried out, and the results show that when the gas?oil ratio is 40,80,160 m3/t, the pipeline can run stably at the gathering temperature 3,4 ℃ and 6 ℃ lower than the WSOT.
In the environment of CO2 enhanced recovery (CCS?EOR), the corrosion cracking behavior and mechanism of X70 pipeline steel under different CO2 pressures were studied. The on?site environment was simulated by using a high?pressure reactor and a simulated produced aqueous solution; the corrosion rate and corrosion mechanism of X70 pipeline steel in the CCS?EOR environment were investigated by electrochemical experiments; the corrosion cracking behavior of X70 pipeline steel under simulated environment was investigated by slow strain rate tensile experiments; finally, the corrosion cracking behavior of X70 pipeline steel under different CO2 pressure was analyzed by scanning electron microscope. The results show that the corrosion rate of X70 pipeline steel increases with the increase of CO2 pressure; the corrosion product film produced on the surface of X70 pipeline steel can not protect the metal matrix, and intensify the local corrosion; under the influence of the corrosion product film, the increase of CO2 pressure makes X70 pipeline steel stress corrosion susceptibility increases; and the corrosion cracking of X70 pipeline steel is also affected by the metal surface cracks.
Energy shortage and environmental pollution have always been the focus of the world's attention. The use of oil, natural gas, and electricity to heat crude oil has high energy consumption and serious environmental pollution. Solar energy, as sustainable and clean energy, has become the focus of researchers from all over the world.Thus, a solar heating crude oil system was designed, and safe and easily available air was selected as the heat transfer fluid. The system consists of a solar receiver, a heat accumulator, a crude oil heat exchanger, and an electro?thermal furnace. The heat receiver receives solar radiation and the temperature rises. The air passes through the heat absorber to obtain high temperature, and the high temperature air enters the heat exchanger to heat the crude oil. A mathematical model for the analysis of the thermodynamic performance of the solar heating crude oil system was established, and the model was verified. Then, the Aspen Plus software was used to conduct thermodynamic analysis of the heatingprocess. The results show that the compressor and the preheater are the components with large exergy loss. When the pressure ratio of the compressor is 2.7, the system reaches its best state. At this situation, the thermal efficiency is 72.35%, the exergy efficiency is 73.89%, and the waste heat recovery efficiency is 72.33%.
The Al?15Si?xNb coating was used as the research object to explore the effect of Nb content on the microstructure and corrosion resistance of the coating. The microstructure of the coating was observed by metallographic microscope, the phase composition of the coating was analyzed by XRD, and the corrosion behavior of the coating in 3.5% NaCl solution was characterized and discussed by electrochemical experimental methods (including open circuit potential, impedance spectrum analysis and polarization curve analysis). The results show that the Al?15Si?xNb coating is mainly composed of α?Al, primary Si and eutectic Si. A small amount of NbAl3 phase and Nb5Si3 phase are formed after Nb element is added to the coating; The addition of Nb promoted heterogeneous nucleation and significantly changed the microstructure distribution of the coating. The microstructure of Al?15Si?10Nb coating has a homogeneous distribution. Uniformly distributed α?Al, primary Si and eutectic Si will form many uniformly distributed corrosion micro?battery. It can promote Al anodic reaction and make the Al2O3 oxide film formed on the coating surface more continuous. The polarization curve of Al?15Si?xNb coating has passivation like characteristics. When 10% Nb is used, the self?corrosion potential and pitting potential of the coating are higher, the product film resistance is larger, and the dimensional passivation current density is lower. Therefore, Al?15Si?10Nb coating has better corrosion.
Screw geometry has an important influence on the mixing characteristics of single screw extruder. Three kinds of six rhombic thread elements, four rhombic thread elements and tooth thread elements with special configuration were selected to design three new combined screws of single screw extruder for different processing requirements, and the flow and mixing characteristics of polylactic acid in the three combined screws were studied. The results show that there is a large pressure gradient at the pressure junction of the combined screw, the diamond thread element can provide high tensile action for the material, the residence time of the fluid in its channel is short, and the mixing performance is relatively poor; the toothed screw element can not only provide high shear effect but also high tensile effect for materials, with long residence time and good mixing effect.
High?speed tensile tests of HC420/780DP dual?phase steel at strain rates of 0.001，0.100，1.000，10.000，100.000 s－1 and 200.000 s－1 were carried out. The dynamic mechanical behavior of the materials under different strain rates was studied. The true stress?strain curves of HC420/780DP at different strain rates were obtained, and the fracture elongation, tensile strength and flow stress were analyzed. The results show that the flow stress, yield strength and tensile strength of HC420/780DP dual?phase steel increased with the increasing strain rate. Based on the modified Johnson?Cook constitutive model, the dependent plastic deformation constitutive model versus HC420/780DP dynamic strain rate was established. The fitting results of the optimized constitutive equation are in consistent with the curves of experimental results.
The dry point of gasoline is difficult to be measured in real time. A large number of data samples need to be extracted to test the quality of each section of the oil. In order to solve this problem, predictive control was carried out by establishing a soft sensor model. The least squares support vector machine model is too sensitive to outliers, which is easy to affect the prediction accuracy. By establishing the weighted least squares support vector machine model (WLSSVM), the fitting error is weighted, which weakens the influence of outliers on the model and improves the anti?interference ability of the model. The improved WLSSVM was applied to the prediction of gasoline dry point. The results show that the maximum absolute error of the improved WLSSVM is 11.65% lower than that of the least squares support vector machine model, and its prediction performance and robustness have obvious advantages.
Aiming at the problem of temperature tracking and balance control of each branch pipe of the heating furnace, an improved genetic algorithm was proposed to optimize the multi?deviation control of the temperature tracking and balance of the branch pipe temperature of the heating furnace. The scheme used the temperature deviation of the raw materials of each branch pipe after mixing and the temperature deviation of each branch pipe. By adjusting the feed flow rate and fuel flow rate, it not only ensured that the flow rate of the main pipe is constant during the regulation process, but also realized the dual goal of temperature tracking and balance of each pass. Multi?passes are analyzed as a whole, so the temperature comparison of adjacent branch pipes was avoided repeatedly. At the same time, the improved genetic algorithm was used to optimize the controller parameters of the differences control technique, which overcomes the difficulty of controller parameter tuning. The simulation results show the feasibility and effectiveness of the improved genetic algorithm to optimize the differences control scheme.
For the MIMO nonlinear systems, a multivariable ORVFL neural network adaptive predictive control algorithm based on Improved Sparrow Search Algorithm was proposed in this paper. The algorithm uses the ORVFL network to approximate the nonlinear system model, and applies to the multi?step prediction of the system process. In order to improve the performance of the Sparrow Search Algorithm, the algorithm is used to optimize the system performance index online and solve the optimal control law of each sampling period. The results show that the algorithm has good control performance and good anti?model mismatch ability.
Gaussian mixture model (GMM) is easily affected by noise, and Markov random field (MRF) model can well describe the spatial characteristics. The combination of the two is suitable for image segmentation with noise, but MRF model is prone to over segmentation. To solve this problem, an improved image segmentation algorithm based on adaptive weight coefficient was proposed, which can segment cerebrospinal fluid, gray matter and white matter from magnetic resonance imaging (MRI). Firstly, the K?means algorithm was used to obtain the initial segmentation results, and the Expectation?Maximization (EM) algorithm was used to estimate the parameters of GMM, and then the joint probability energy function of the pixel gray level of the image was obtained. Then, the adaptive weight coefficient was obtained by using the gray value, posterior probability and Euclidean distance of the center pixel and the neighboring pixels of the MRF neighborhood system, and the prior probability energy function was obtained by MRF. Finally, the final image segmentation results were obtained by Bayesian criterion. Experimental results show that the algorithm has strong adaptability, can better overcome the impact of noise on image segmentation. Compared with similar algorithms, the proposed algorithm has higher segmentation accuracy for brain MR images with noise, and obtains better segmentation results.
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