CsLaTa2O7/Na2Ta2O6 heterostructure photocatalyst was constructed via the growth of pyrochlore⁃type Na2Ta2O6 particles on the surface of layered structure CsLaTa2O7 using its metastable property through hydrothermal method. The CsLaTa2O7/Na2Ta2O6 was characterized by XRD, SEM, TEM, UV⁃Vis spectroscopy and PL spectroscopy. The results show that the CsLaTa2O7/Na2Ta2O6 heterostructure can effectively inhibit the recombination of photogenerated electrons and holes, and its photocatalytic performance under UV light is significantly higher than that of single phase. Methylene blue can be completely degraded within 10 min under the illumination of ultraviolet light.
The rice bran wax was firstly extracted by solvent from rice bran, and triacontanol was thenextracted after refining. The extraction conditions were determined through the investigation of solvent type, extraction temperature, time and other factors. After refining, the optimum conditions for extracting triacontanol were determined, and the corresponding products were characterized by infrared spectroscopy. The experimental results show that the yield of crude rice bran wax is 1.0%~1.5% under the conditions of isobutanol as extractant, isobutanol/rice bran mass fraction ratio of 10, extraction temperature of 105 ℃ and extraction time of 5 h. In addition, the yield of refined rice bran wax is 3.1% under the conditions of saponification temperature 55 ℃, reaction time 8 h, sodium hydroxide concentration 3 mol/L and ethanol calcium chloride as extraction solution. The infrared spectrum analysis indicated that the melting point of the product is 85.0~86.5 ℃.
A synthetic method for forming α,β⁃unsaturated ketones through aldol condensation was studied. The formation of C-C bonds of 4⁃phehyl⁃3⁃buten⁃2⁃one was achieved under a metal⁃free condition in the presence of NaOH. The reaction conditions were mild and the selectivity was strong.The reaction mechanism was measured and the structure of the target product was analyzed by various characterization methods to confirm the structure of the target product.
Microbes can improve the fluidity of waxy crude oil and increase the efficiency of transportation. The cultured Bacillus subtilis 6# and Pseudomonas aeruginosa 3# were mixed and cultured in a ratio of 2∶3, the growth conditions were optimized. DSC, polarizing microscope, HAKEE rheometer and interfacial tensiometer were used to analyze the effect of compound bacteria and waxy crude oil. The results showed that: after treatment with compound bacteria, the wax precipitation point of waxy crude oil decreased by 2.23 ℃, the peak point of wax precipitation decreased by 2.71 ℃, and the wax content of crude oil decreased by 51.64%; the wax crystal structure changed significantly; the apparent viscosity of crude oil decreased by 64.72% at 37 ℃. In addition, the emulsification index of the compound bacteria on liquid paraffin was 55.39%, and the surface tension of the liquid paraffin culture medium was reduced from 79.89 mN/m to 38.83 mN/m. Compared with single bacteria, compound bacteria are more effective in removing wax and reducing viscosity, and have wider application prospects.
The effects of different valence inorganic salts on the performance of sodium petroleum sulfonate (NPS) emulsion were investigated by observing the apparent viscosity, interfacial tension and dehydration rate of crude oil emulsion. The results show that NaCl and KCl can be enhanced the action of NPS in a certain concentration range. When the concentration of NaCl and KCl are 9 mmol/L and 12 mmol/L, NaCl and KCl can increase the apparent viscosity of emulsion by 224.03 mPa•s and 122.48 mPa•s, the interfacial tension can decrease by 10.6 mN/m and 9.6 mN/m, and the dehydration rate can reduce by 10.7% and 8.2%, respectively. As the concentration of inorganic salts MgCl2 and CaCl2 increases, MgCl2 and CaCl2 can decrease the apparent viscosity and increase the dehydration rate of NPS emulsion, while the interfacial tension decreases first and then increases.
A series of SAPO⁃34 molecular sieves with different crystallization time were synthesized by hydrothermal method using pseudo⁃boehmite, silica sol and phosphoric acid as raw materials, TEA & TEABr as template. The crystal structure and physicochemical properties of the synthesized SAPO⁃34 molecular sieve were characterized by XRD, SEM and NH3⁃TPD. The catalytic activity of MTO was evaluated in a fixed bed reactor. The results showed that pure phase lamellar SAPO⁃34 molecular sieves were synthesized under different crystallization time. The longer the crystallization time was, the higher the crystallinity was, the greater the lamellar thickness was, and the more the acid centers were. At 450 ℃, 2 h-1, 0.2 MPa, crystallization time 72 h, the SAPO⁃34 molecular sieve had the best MTO catalytic activity with a single⁃pass lifetime 360 min and yield of diene 86.8%.
Porphyrins, as an organic photosensitizer in medicine, play a very important role in photodynamic therapy. Their main mechanism is to absorb laser energy to produce reactive oxygen species, so as to achieve therapeutic purposes. In this paper, the basic synthetic route, the characteristics of each generation of porphyrin photosensitizers and the scientific research of porphyrin photosensitizers are reviewed. At present, porphyrin photosensitizers are widely used in photodynamic therapy, and with the development of new photosensitizers, photodynamic therapy will have a prominent application prospect in clinical treatment.
The composite PCM was prepared by vacuum impregnation method. Natural bentonite and lauric acid (LA) were used as supporting material and PCM, respectively. The results show that the addition of flake graphite not only improves the thermal conductivity of the composite phase change material, but also prevents the phase change material from leaking out of the composite phase change. After 200 thermal⁃cold cycling treatment, the prepared form⁃stable composite PCM still shows a good performance of thermal reliability and has potential to be used in the thermal energy storage system.
At present, the application demand of polymer flooding technology is shifting from low⁃salt reservoirs to high⁃salt and extra⁃high salt reservoirs. Improving the adaptability of polymers in high⁃salt reservoirs has become a technical problem that petroleum science and technology workers need to solve urgently. In order to improve the recovery rate of the target reservoirs, the “Chang 4+5” high⁃salt oil reservoir block of Changqing Oilfield was mainly based on the knowledge of physical chemistry, polymer materials science and reservoir engineering, through instrument detection and chemical analysis and physical simulation and other experimental methods, under the conditions of high salinity solvent water, the polymer solution reservoir adaptability study. The results show that the core permeability limit of the polymer solution is Kg=(25～40)×10-3 μm2 when the relative molecular mass is M=800×104 under the conditions of polymer concentration of CP=300～900 mg/L, permeability limit Kg=(30～55)×10-3 μm2 when M=1 400×104, Kg=(35～70)×10-3 μm2 when M=1 700×104 ,when M=2 000×104, Kg=(45～80)×10-3 μm2. Under the conditions of water and keep temperature injection in the target reservoir, the adaptability between reservoir rock and polymer solution is affected by rock permeability, polymer relative molecular mass and concentration. The top of the correlation curve is the compatibility area, and the lower part is the blocking area. The "hole throat radius median/Dh " ranged from 3.02 to 5.76 in the target reservoir.
Corrosion resistance of stainless steel is closely related to the formation conditions of passivation film. The effects of film⁃formation potentials on the characteristics and electronic structure of passivation films on 2205 duplex stainless steel surface in 3.5% NaCl solution were explored by potentiodynamic polarization technique, electrochemical impedance spectroscope, and Mott⁃Schottky methods. The results show that with the increase in film⁃formation potential, the passivation film is first porous and then becomes dense. However, under the film⁃formation potential of 0.90 V, the passivation film finally underwent an additional porous structure process. With the increase of film⁃formation potential, donor density and acceptor density in passivation film increase, and the formation rate of passivation film increase. However, the adsorption of erosive anion is also promoted by the increase of film⁃formation potential. The defects and porosity of the outer layer of passivation film increase with the increase of potential, which led to the increase of passivation film thickness. The compactness of the inner layer of the passivation film is the best under the film⁃forming potential of 0.60 V(SCE). With the increase of the potential to 0.90 V(SCE), the inner layer oxide becomes porous, the compactness of the passivation film degraded, and the rupture risk of the passivated film is the highest.
In order to solve the problem that the angle of crack and magnetization direction was too small to identify in the pipeline magnetic flux leakage internal detection, the influence of crack angle on magnetic flux leakage detection signal and the characteristics of crack magnetic flux leakage signal under the condition of axial excitation of DC electromagnet were analyzed. Comsol finite element simulation software was used to simulate and analyze the crack defects of 0.2 mm in different angles of the inner wall of the pipeline. DC electromagnet axial excitation experimental platform was built, and EDM technology was used to process the specimens with different angles of crack to carry out the dragging experiment of the crack angle. Results show that the minimum detectable angle of crack and magnetization direction is 25°. The peak value of MFL signal decreases with the decrease of crack angle, larger the signal span, the greater the influence of noise signal. When the magnetization direction is perpendicular to the crack, the maximum span of MFL signal amplitude is the smallest, and when the magnetization direction is parallel to the crack, no MFL signal is generated.
Based on the traditional prediction model of triangular fuzzy accident tree, which had the defect of large error caused by linear approximation, the source of error was analyzed according to the truncated set theorem, and the improved algorithm for drawing membership curve of triangular fuzzy number of accident treetop events was given according to the representation theorem. Matlab software was used to program, the modified and traditional triangle fuzzy accident prediction algorithms were used to predict the electrostatic accumulation accidents in oil depots, and calculated the fuzzy importance of 8 causes. According to the calculation results, compared with the traditional algorithm, the average error value of the fuzzy importance calculation of the eight basic events is reduced by 11.91%，which shows that the modified algorithm greatly optimizes the shortcomings of the traditional algorithm.
The calculation models of electric field and temperature field in the continuous graphitization furnace were established. The thermoelectric coupling calculation of the graphitization process was carried out by using the numerical calculation method. Then the distribution of electric field and temperature field in the furnace was obtained. The results show that the heating area of the graphitization furnace is mainly concentrated between the two electrodes. The distribution trends of electric field intensity and current are the same, and the high values of both are distributed near the electrode. The high temperature region is distributed in the middle and lower part of the two electrodes, and the temperature can reach above 2 400.0 ℃. However, the size of the high temperature region is directly related to the electrode parameters. With the narrowing of electrode distance, the high temperature region expands, the temperature peak increases and the temperature raising level increases. With the increase of electrode diameter, the high temperature area expands and the peak temperature increases. With the increase of electrode insertion material length, the high temperature area expands, the temperature peak increases and the temperature raising level decreases.
In order to improve the efficiency and accuracy of fault diagnosis of power supply and distribution system in intelligent buildings, a fault diagnosis method based on Bayesian network and wavelet transform was proposed. Firstly, the topological structure of power supply and distribution network in intelligent buildings was analyzed in detail in theory. Secondly, the switching and electrical quantities in fault information were filtered and reorganized by wavelet transform. Finally, the fault information after the reorganization was modeled and analyzed by Bayesian network, and the fault diagnosis results were obtained. In this paper, the process of extracting electrical and switching quantities from fault information was introduced in detail. According to the fault characteristics of the existing intelligent building power supply and distribution system, the corresponding recovery strategy was given. IEEE⁃39 multi⁃node complex power fault system is taken as an example, the simulation results show fault diagnosis result of the proposed method is fast and accurate. The research results have important reference value for fault diagnosis research of intelligent building power supply and distribution network.
In the petrochemical process, a risk monitoring and early warning system for hazardous chemicals is designed based on CPS technology to solve the problems of monitoring, identification and prediction of major hazard sources of hazardous chemicals. The system is divided into three layers: physical layer, network layer and decision layer. At the physical layer, the front⁃end hazardous chemicals data collection, data transmission and local storage are completed, and the data are classified and transmitted to the cloud server in real time. The data passes through the network layer and is identified by the decision⁃making layer for major hazard sources and early warning for hidden dangers of hazardous chemicals. Finally, the whole data is displayed. Genetic algorithm and neural network algorithm are used in the decision⁃making level for risk assessment of major hazard sources. Simulation experiments show that this method can accurately complete the risk assessment of major hazard sources of hazardous chemicals. In the laboratory, the remote monitoring and early warning system for hazardous chemicals based on CPS is proved to have the capability of hazard source identification and risk hazard prediction through actual verification.
In this paper, a new watermarking scheme based on Chaos for image authentication and tamper detection is proposed. This scheme can detect any modification to the image and determine the specific location of the modification. In order to improve the security of the proposed scheme, two chaotic maps are used. Because the chaotic map is sensitive to the initial value, the corresponding position relationship between the pixels in the watermarking image and the watermarking is disturbed, which makes the watermarking scheme resist forgery attack. In this scheme, the initial value of the chaotic map is used as the secret key, and the effectiveness of the proposed scheme is checked through a series of attacks. The experimental results show that the scheme is not only safe and reliable, but also can achieve high tamper detection and location accuracy under different attacks.
