Research Progress on Anode Protection Strategies of Lithium Sulfur Battery
Cao Yongan， Zhang Zixin， Hao Xiaoqian， Wang Wenju
2021, 41 (2): 1-7. DOI:10.3969/j.issn.1672-6952.2021.02.001
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Due to its advantages of high energy density and low cost, lithium sulfur battery has become a potential choice for electric vehicles and new energy storage devices. Anode protection has become a hot topic in recent years. By optimizing the anode, lithium dendrites can effectively be alleviated which can solve the problem of battery cycle life decreasing. In this paper, the strategy of anode protection for lithium sulfur battery was introduced from the aspects of electrolyte additive and anode structure design, and the mechanism of action was briefly described. Finally, the strategy development of lithium sulfur battery anode protection was prospected.
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Synthesis, Structure and Optical Properties of a Layered Ce Coordination Polymer
Chen Yaxu， Wang Xin， Guan Lei
2021, 41 (2): 8-12. DOI:10.3969/j.issn.1672-6952.2021.02.002
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A layered coordination polymer, [Ce(L)(H₂O)₄]_n (1), was synthesized by hydrothermal method by the reaction of 5⁃sulfoisophthalic acid monosodium salt (NaH₂L) with cerium nitrate hexahydrate. Its molecular structure and composition were measured by single crystal diffraction, elemental analysis and thermogravimetry. Each Ce³⁺ was nine coordinated with the coordination geometry of three⁃capped triangular prism. The central Ce³⁺ could be bridged by the carboxylate and sulfonate groups of the L^3- ligands, forming a two⁃dimensional layered structure. The interlayers were connected by the hydrogen bonds between the coordination water molecules and oxygen atoms of functional groups, increasing the stability of the structure. The fluorescence measurement results show that compound 1 exhibits the characteristic fluorescence emission peak of the ligand at 427 nm. It also has the second⁃order nonlinear optical property, and its intensity is 0.7 times of that of potassium dihydrogen phosphate (KDP).
A layered coordination polymer, [Ce(L)(H₂O)₄]_n (1), was synthesized by hydrothermal method by the reaction of 5⁃sulfoisophthalic acid monosodium salt (NaH₂L) with cerium nitrate hexahydrate. Its molecular structure and composition were measured by single crystal diffraction, elemental analysis and thermogravimetry. Each Ce³⁺ was nine coordinated with the coordination geometry of three⁃capped triangular prism. The central Ce³⁺ could be bridged by the carboxylate and sulfonate groups of the L^3- ligands, forming a two⁃dimensional layered structure. The interlayers were connected by the hydrogen bonds between the coordination water molecules and oxygen atoms of functional groups, increasing the stability of the structure. The fluorescence measurement results show that compound 1 exhibits the characteristic fluorescence emission peak of the ligand at 427 nm. It also has the second⁃order nonlinear optical property, and its intensity is 0.7 times of that of potassium dihydrogen phosphate (KDP).
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Synthesis of Various Novel Chiral Phosphoric Acid Catalysts
Zhu Liming， Yu Fang
2021, 41 (2): 13-16. DOI:10.3969/j.issn.1672-.2021.02.003
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A variety of novel chiral phosphoric acid catalysts were synthesized from R⁃binaphthol via hydroxyl protection, halogenation, coupling, deprotection, phosphorylation and hydrolysis. The chiral phosphoric acid catalysts synthesized were mainly chiral phosphoric acid catalysts with nitro substituents, because the addition of nitro substituents could increase the acidity of phosphoric acid and provide a catalyst for some reactions requiring a stronger acidic catalytic system. By our method, about 10 g of nitro⁃substituted chiral phosphoric acid catalyst could be synthesized in one time in a high yield, which provided great convenience for asymmetric catalytic reaction.
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Catalytic Synthesis of 2⁃Phenylthioethanol under Mild Conditions
Chen Shuai， Wang Rui， Gong Hong， Wei Yushi， Wang Jiale， Zhang Chi， Min Jiachen
2021, 41 (2): 17-20. DOI:10.3969/j.issn.1672-6952.2021.02.004
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2⁃Phenylthioethanol was synthesized from thiophenol and ethylene carbonate using 1,5⁃diazabicyclo[4.3.0]non⁃5⁃ene (DBN) as a catalyst. The effects of catalyst type and amount, reaction time and temperature on the reaction were studied. The results showed that, the conversion of 2⁃phenylthioethanol can reach more than 90% when the reaction temperature is 50 ℃ and 100% conversion can be obtained when the reaction temperature is 90 ℃ using DBN as the catalyst, n(thiophenol)/n(DBN)=100, the reaction time 10 min. The selectivity of the catalyst of the synthetic route is 100% The paper discusses the reaction mechanism according to the theory of soft and hard acid and alkali.
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Research Status on High Temperature Oxidation of Micro⁃Arc Oxidation of Titanium Alloy
Hao Guodong， Su Shuangyue， Hao Chunli， Liu Binxia
2021, 41 (2): 21-26. DOI:10.3969/j.issn.1672-6952.2021.02.005
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Titanium alloy is widely used in military and civil fields because of its high strength, corrosion resistance and high specific strength. However, high temperature oxidation reaction will occur when it is used in a high temperature environment, which reduces its performance and limits its application range.Ceramic coatings are prepared in situ on the surface of titanium alloy by means of Micro⁃arc oxidation(MAO) technique. The combining capability of ceramic layer and metal substrate is very strong, has good wear resistance, corrosion resistance and resistance to high temperature and other characteristics, the technological process is simple and efficient, low cost and is friendly to the environment, can greatly improves the oxidation resistance of titanium alloy, prolong its service at high temperatures.This paper reviews the research status of micro⁃arc oxidation technology in the field of high temperature oxidation resistance of titanium alloys.The influences of reaction parameters, electrolyte, reaction time and power mode on the structure and high temperature oxidation resistance of micro⁃arc oxide ceramic coatings are summarized.
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Preparation and Properties of Poly(Lactic Acid)/Wood Flour Composites with High Heat Resistance
Xia Yiwei， Li Shiyi， Feng Yulin， Zhao Guiyan， Li Lanting， Wang Changhe
2021, 41 (2): 27-31. DOI:10.3969/j.issn.1672-6952.2021.02.006
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Widespread application of PLA is limited because of its slow crystallization rate and low heat deflection temperature. The poly (lactic acid) (PLA) with wood flour (WF) and a small amount of multi amide compound (MA) were successfully prepared by melt blending. The crystallization kinetics, heat resistance and mechanical properties of PLA composites were studied. When the addition of wood flour was 30.0% and multi amide compound was 0.3%, DSC results show that the crystallization rate of isothermal and non⁃isothermal improved dramatically, and correspondingly the Vicatsofting point of PLA composites increases to 146.5 ℃, higher than that of neat PLA 61.6 ℃, the heat resistance of PLA is improved dramatically. Moreover, mechanical properties of the PLA composties are studied. The tensile strength of the PLA/WF and PLA/WF/MA samples is increased slightly. It is concluded that the combination of wood flour and the multi amide compound have a synergistic effect on PLA crystallization behavior to producehigh heat resistance PLA composites.
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Preparation of MnFe₂O₄/TiO₂ and Its Fenton⁃Like Photocatalytic Properties
Wang Xiaodi， Li Lihua， Zhang Jinsheng， Wu Xian， Ma Cheng
2021, 41 (2): 32-36. DOI:10.3969/j.issn.1672-6952.2021.02.007
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MnFe2O4/TiO2 Fenton⁃like photocatalyst was successfully prepared by sol⁃gel method, the structure and morphology of the sample were characterized by XRD, SEM and UV⁃vis. MB was used as the target pollutant for degradation, and the photocatalytic properties of products with different doping amounts were investigated in visible light. The results show that: The degradation rate of TMF Fenton⁃like photocatalytic reaction to MB is up to 96.8%, under the optimum conditions, in the iodine⁃tungsten lamp with a light source of 300 W, the doping amount of MnFe2O4 to TiO2 is 2%, the mass of catalyst is 60 mg, pH=11, and the concentration of H2O2 is 8 mmol/L . Under the same conditions, compare with the undoped pure TiO2, the catalytic performance of MnFe2O4/TiO2 for MB under visible light is significantly improved.
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Evaluation of Development Effectiveness and Development Technology Policy Research of Chang 8 Reservoir in C335 Area of JY Oilfield
Zhang Weigang， Wang Jing， Guo Longfei， Zhang Tianya， Zhao Xiaohong， Chen Zhenwan
2021, 41 (2): 37-41. DOI:10.3969/j.issn.1672-6952.2021.02.008
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In view of the problems of difficult establishment of effective displacement system and poor effect of water drive in Chang 8 reservoir of C335 area of JY oilfield, the reservoir development effect was evaluated comprehensively by reservoir pressure change, water drive law and effect characteristics. On this basis, combining with reservoir engineering and numerical simulation, this article formulated reasonable exploitation policy. The optimum injection⁃production ratio was 2.0, the flow pressure was 6.0 MPa, and the production rate was 0.7%. Finally, by comparing and forecasting the three schemes, the comprehensive scheme was the best.
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Effect of Recombination of Dilute Salt and Surfactant on Hydrate Formation
Xia Bin， Ma Guiyang， Yin Siwen， Jin yuan
2021, 41 (2): 42-50. DOI:10.3969/j.issn.1672-6952.2021.02.009
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Under natural conditions, natural gas hydrates are found in marine environments. Therefore, it is necessary to study the formation of hydrates under salt water conditions and their basic properties. The effect of low⁃concentration MgSO4 with sodium dodecyl sulfate (SDS), alkyl glycoside (APG), dodecyl trimethyl ammonium chloride (DTAC) and other surfactants on the formation of hydrates was studied. The changes of pressure and temperature with time during the formation of hydrate were measured under the conditions of 275.15 K and 6 MPa. The results show that when a certain concentration of SDS or APG is added to the solution, the hydrate formation is significantly promoted. When a certain amount of DTAC is added, substantially no hydrate is formed in the solution. Furthermore, low concentration of MgSO4 significantly enhanced the promoting effect of surfactants. It can be seen that low concentration of MgSO4 and appropriate concentration of surfactant will promote the formation of methane hydrate, and different types of surfactants have different effects on the formation of hydrate. Compared with the promotion effect of SDS and APG on hydrate formation, the promotion effect of DTAC on hydrate formation is not obvious.
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Comprehensive Evaluation of Oil Depot Construction Scheme Based on Entropy Weight Analysis
Fan Ying， Shi Tingyi， Wang Yingying， Tong Zhen， Wu Yuguo
2021, 41 (2): 51-58. DOI:10.3969/j.issn.1672-6952.2021.02.010
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Construction standardization and civilization are not only the minimum requirements of the construction site, but also the innovation of the construction field in the new era, which are related to the social and economic development and the process of national modernization.Based on the recruitment and bidding information of an oil depot and taking four different construction schemes as the basic data, a standardized construction management evaluation index system was firstly constructed. On this basis, the standardized construction scheme evaluation system was constructed by entropy weight method and comprehensive evaluation method. The results show that the degree of standardization and civilization of the four schemes is ranked as M3＞M4＞M1＞M2. The first⁃level index weight ranking is environment＞safety＞energy saving＞cost＞quality＞progress. Among them, the weight proportion of environment factor is the largest, about 0.193, and the weight proportion of project progress factor is the smallest, about 0.128. Therefore, during the construction of oil depot, the emphasis should be placed on construction environment and safety construction, and the road of green, standardized and sustainable development should be taken.
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Risk Analysis of Feeding System of Gasifier Based on Dynamic Bayesian Network
Jin Yu， Liu Ming， Sun Tie， Duo Yili
2021, 41 (2): 59-64. DOI:10.3969/j.issn.1672-6952.2021.02.011
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Aiming at the shortcomings of dynamic risk analysis in large gasification units, a method of dynamic Bayesian network based risk analysis of gasifier feed system was proposed. The fault tree model was established by using the relevant data of failure forms of each unit of gasifier feeding system, and the fault tree model was transformed into a Bayesian network model. The bayesian network model was optimized by K⁃2 algorithm, and the influence of common cause failure on the system was processed by β factor method. Considering the influence of maintenance factors on the failure rate of the system at each moment, the accuracy and feasibility of the proposed method were verified by using the Bayesian network analysis software GeNIe and Monte Carlo. The results show that the dynamic Bayesian network has the advantages of accurate dynamic risk analysis and the ability to identify the weak links in the gasifier feed system risk analysis. According to the analysis results, a reasonable reliability allocation strategy can be obtained.
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Numerical Simulation of Gas⁃Liquid Two⁃Phase Splitting Characteristics of T⁃Shaped Multi⁃Branch Pipeline
Sun Zhanwei， Zhu Xiangzhe
2021, 41 (2): 65-72. DOI:10.3969/j.issn.1672-6952.2021.02.012
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T⁃shaped multi⁃branch pipeline is a kind of T⁃shaped pipeline with complex multi⁃branch structure, which is now widely used in the research of two⁃phase and multi⁃phase flow.In this article,the fluid simulation tool Fluent was used to simulate the oil and gas two⁃phase flow in the T⁃shaped pipeline at different times with obtained the oil and gas separation characteristics of each branch and the mass flow data of the inlet and outlet.The results indicate that, when the oil and gas two⁃phase mixed infusion flows through the T⁃shaped pipeline, the phase distribution of the oil and gas two⁃phase in the pipeline is uneven due to the effect of gravity.With the increase of time, the gas⁃outlet at the top is mostly gas, while the oil⁃outlet at the bottom is mostly liquid, thus achieving a initial separation of oil and gas. T⁃shaped pipeline with different branch pipe heights are selected for simulation, and the characteristics of oil⁃gas separation phenomena are analyzed. Then select different inlet velocity of T⁃shaped main pipe to observe the effect of inlet velocity on oil⁃gas separation.Finally, by analyzing the turbulent vortex structure and flow field characteristics in the pipeline, the turbulence coherent structure shows the characteristics of regularity and repeatability under the same structural parameters, and the influence of branch pipeline on flow pattern and turbulence vortex.
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Proposition and Application of Nonlinear Multi Factor Coupling Accident Cause Model
Zhang Yuanyuan， Zhang Juwei， Liu Xiaopei
2021, 41 (2): 73-78. DOI:10.3969/j.issn.1672-6952.2021.02.013
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In view of the shortcomings of the existing accident causation models, such as simple listing and superposition of causative factors, not considering the coupling effect between factors, unable to make quantitative analysis and so on,a new nonlinear multi⁃factor coupling accident causation model was proposed and applied to the prevention of oil depot accidents. In the new model, the calculation formulas of the main influencing factors, the influence coefficient and the multi factor coupling rheological nonlinear damage were proposed. The most prominent feature of the model is that it can distinguish the dynamic influence of the rheology of the main influencing factors on the damage of the complex system under the coupling action of multiple factors. MATLAB software was used to simulate the changing state of the oil depot system after single factor rheology, main influencing factor rheology and non⁃main influencing factor rheology. The results show that the main factor affecting the safety of oil depot is the lack of safety consciousness,and the lack of safety consciousness of oil depot personnel has the greatest influence on other factors. For oil depot accident prevention, according to the nonlinear multi⁃factor coupling accident cause model proposed in this paper, it is necessary to take effective measures to control the main influencing factors and seize the main time nodes.
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Research on Fault Line Selection Method of Distribution Network Based on MEEMD
Kan Zhe， Yang Fan， Han Jingyu， Sun Zhen， Wu Dongxu
2021, 41 (2): 79-84. DOI:10.3969/j.issn.1672-6952.2021.02.014
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To solve the problem of distribution network fault line selection caused by too few frequency components and no high amplitude low frequency components in the characteristic frequency band of transient zero sequence current, an improved ensemble empirical mode decomposition (MEEMD) method is proposed. Firstly, the influence of distributed generation on line zero sequence current was considered; then, the zero sequence current after fault was decomposed into multiple frequency signals according to frequency by meemd, and the eigenmode function was obtained and the highest frequency component is extracted; finally, the line selection result was obtained by analyzing the signal waveform of the highest frequency. The basic signal was not needed in this process, so the characteristics of the obtained signal were closer to the original signal. The process of fault line selection based on meemd was described in detail, and the influence of multi scene distribution network considering distributed generation on fault line selection is discussed. The simulation results show that the method can effectively improve the accuracy of fault line selection.
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H_∞ Output Tracking Control Based on Mode⁃Dependent Average Dwell Time
Liu Chao， Nie Hong， Chen Li
2021, 41 (2): 85-91. DOI:10.3969/j.issn.1672-6952.2021.02.015
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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.
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Research on Personalized Web Search Algorithm Based on Vector Space Model
Lu Yang， Shi Yuanbo
2021, 41 (2): 92-96. DOI:10.3969/j.issn.1672-6952.2021.02.016
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In order to solve the problem that different users have different expectations for search results in information retrieval, a personalized web search algorithm based on vector space model was proposed.In view of the different interests of users, user portraits could more comprehensively express the characteristics of user interests. The vector space model was used to establish user portraits to express user interests, combined with traditional web page ranking algorithms to obtain the final web page ranking results. Different web search results could be obtained for different users, and the number of web pages that meet user interests increases in the top ranking web pages. Through the analysis of the experimental results of simulated web search, it was proved that this algorithm was better than the traditional PageRank algorithm in personalized web search.
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