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.

As an important semiconductor photocatalytic material, bismuth oxide (Bi₂O₃) is considered as a promising visible photocatalyst due to its special electronic structure and excellent visible light response performance. It displays a good application prospect in photocatalytic treatment of wastewater. However, the application of Bi₂O₃ is limited by its low photocatalytic performance, therefore, Bi₂O₃ pholocatalyst with superior performance is expected to be obtained by modifying methods by the researchers. In this review, a series of modification methods, such as surface morphology regulation, surface modification, metal ion modification and semiconductor combination, are summarized. Then, the future development of modified Bi₂O₃ photocatalytic materials is prospected.

In the multiphase flow pipeline transportation system， in the process of hydrate slurry flow， rugged terrain will be encountered. At this time， the use of inclined pipeline is particularly important. Therefore， the influence of the flow characteristics of gas hydrate slurry in the inclined pipe on the blocked pipeline was studied. The hydrate plugging experiment of oil + natural gas in oil?based system was carried out on the low?temperature and high?pressure visual hydrate experimental loop， and the effects of initial pressure， initial flow and other factors on the flow and plugging time of natural gas hydrate slurry were explored. At the same time， the micro changes of hydrate particles in the process of hydrate formation， flow and pipe plugging were analyzed by real?time online particle tester. The experimental results show that with the increase of initial pressure， the induction time， formation time and slurry flow time of natural gas hydrate are shortened， and the pipe plugging trend of natural gas hydrate increases. With the increase of initial flow rate， the induction time， formation time and slurry flow time of natural gas hydrate are prolonged， and the pipe plugging trend of natural gas hydrate is reduced. Finally， the process from hydrate formation to pipe plugging and the plugging mechanism were analyzed. The research results of gas hydrate plugging pipelines in oil?based systems show that the probability of gas hydrates blocking pipelines can be effectively reduced by reducing initial pressure and increasing initial flow rates in oil?based systems. The research results can provide theoretical reference and basis for maintaining and ensuring the safe flow of natural gas hydrate in pipelines.

Titanium sulfate was used as a raw material, and a titanium oxide (TiO₂) was prepared by direct high?temperature calcination in a muffle furnace. FT?IR, XRD, UV?Vis, SEM were used to characterize the structure of the catalyst. The results show that the direct calcination method can prepare anatase titanium dioxide and apply it to the oxidative desulfurization of dibenzothiophene. Using acetonitrile as the extractant and titanium oxide as the catalyst, the oxidation method was used to remove dibenzothiophene from the simulated oil. The effects of catalyst dosage, reaction temperature, n(H₂O₂)/n(S), and different sulfur compounds on the desulfurization effect were investigated, and the recycling performance of the catalyst was also investigated. Under the optimal desulfurization conditions, the desulfurization rates of dibenzothiophene, 4,6?dimethyldibenzothiophene, benzothiophene, and mixed diesel are 99.5%, 35.6%, 65.0%, and 53.4%. After the catalyst was recycled five times, the catalytic desulfurization effect was still as high as 90.3%.

For a long time, fabric defect detection has been completed by quality inspectors. Meanwhile, the process of defect discrimination is greatly affected by subjective factors and has the problems of low detection efficiency and high cost. With the close combination of computer vision technology and various fields, fabric defect detection system based on vision has gradually become an important solution to replace manual quality inspection. For the fabric defect detection based on vision, this paper reviews the aspects including industry development, general detection standards, overall structure of the system and key technologies in detection algorithms, introduces the existing fabric defect detection products based on vision in the market, analyzes the common defect detection standards and the basic structure of the detection system, and summarizes and compares the research status of image processing and deep learning technology in the field of fabric defect detection in recent years. Finally, the paper summarizes the key problems to be solved, and discusses the possible development direction in the future.

As the greenhouse effect becomes gradually significant, CO₂ capture and storage (CCS) has turned into a potential emission reduction measure, and the adsorption method of CO₂ capture is one of the most promising technologies. Porous solid adsorbents have attracted widespread attention due to their excellent CO₂ adsorption performance. This review focused on the research of CO₂ removal by adsorption. Five different adsorption materials were introduced, and the main factors affecting CO₂ adsorption were summarized, as well as the adsorption performance of modified materials. The results show that the changes of temperature, pressure, and pore structure can affect the physical adsorption properties of the materials; reduction, oxidation, and metal ion loading modification can improve the CO₂ adsorption performance by Changing the type or number of functional groups on the surface of the material.

With the development of artificial intelligence technology and big data Internet technology, the pipeline leak detection technology is developing in the direction of intelligence. Based on the classification of continuous pipeline leak detection technology and discontinuous pipeline leak detection technology, this paper introduced the principles of various leak detection methods, summarized and analyzed the research status of long?distance oil pipeline leak detection technology at home and abroad. The application of combined oil pipeline leak detection and location technology in long?distance oil pipeline detection was prospected.

With the rapid development of human?computer interaction, electronic skin, wearable electronics and other emerging fields, flexible strain sensing materials as one of the core components have become the hot spot of the current research. The conductive polymer composites composed of conductive material and flexible polymer have the advantages of good flexibility, light weight, easy processing and forming, and the conductive property of the material changes under strain stimulus, so it can be used as flexible strain sensing material. This paper reviewed the classification and characteristics of flexible strain sensing materials based on conductive polymer composites, introduced the strain response mechanism of different sensing materials in detail, and summarized the factors that affect the strain sensing performance of conductive polymer composites.

Guaiacol (GUA) is extensively used as the model compound in catalytic studies of lignin, a most abundant renewable aromatic resource in nature. However, GUA is not easy to obtain good activity and selectivity in the hydrodeoxygenation reaction due to its complex structure with various reaction possibilities. So far, researchers have done great efforts to develop efficient catalysts and reaction processes for breakthroughs. This paper reviewed the research progress of transition metal catalysts and noble metal catalysts for hydrodeoxygenation of GUA, and discussed the reaction pathways and the factors which may affect the catalytic behavior, particularly focusing on their catalytic conversions of GUA to phenol or cyclohexanol through C_AR-O bond cleavages and aromatic ring saturation. A prospect regarding the future research directions on the catalyst improvement and reaction process optimization were also presented.

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.

For the under?expansion jet generated after the failure leak of high?pressure pipeline, the Birch theory model was used to replace the actual pipeline leak hole with a pseudo?source. Under different conditions of Hydrogen Blend Ratio (HBR), leak hole size and pipeline running pressure, the concentration field distribution, explosion hazard boundary and explosion hazard range of hydrogen?doped natural gas pipelines after leakage and diffusion were studied. The results show that with the increase of HBR, the aggregation of HDNG after leak diffusion is reduced, the explosion hazard range is gradually decreased and the distal hazard is reduced. However, the increase of HBR shifts the position of explosion hazard boundary downward and increases the proximal hazard. With the increase of leak hole size and pipeline pressure, it will increase the influence area of HDNG after leak diffusion, which will move the explosion hazard boundary position upward and increase the explosion hazard range gradually and increase the distal hazard.

This paper proposes a model?free control protocol design method based on off?policy reinforcement learning for solving the optimal consensus problem of heterogeneous multi?agent systems with leaders. The dynamic expression of local neighborhood error is complicated for the heterogeneous multi?agent systems because of its different system state matrices. Compared with the existing solution of designing observer for distributed control of multi?agent system, the method of solving global neighborhood error state expression proposed in this paper reduces the complexity of calculation. Firstly, the dynamic expression of global neighborhood error of multi?agent system constructed from augmented variables is established. Secondly, the coupled Bellman equation and HJB equation are obtained through the value function of quadratic form. Then, the Nash equilibrium solution of the multi?agent optimal consensus is obtained by solving the optimal solution of the coupled HJB equation, and the Nash equilibrium proof is given. Thirdly, an off?policy Q?learning algorithm is proposed to learn the Nash equilibrium solution of the multi?agent optimal consensus. Then, the proposed algorithm is implemented by using the critic neural network structure and gradient descent method. Finally, a simulation example is given to verify the effectiveness of the proposed algorithm.

In recent years, with the continuous development of nanotechnology and oilfield development technology, nanomaterials have been widely used in water shutoff and profile control agents and have achieved varying degrees of development. This article reviews the research progress and latest achievements of nanomaterials in water shutoff and profile control from four aspects: foam, polymer gel, emulsion, and superfine cement slurry, and analyzes the use of nanomaterials in water shutoff and profile control agents. The mechanism of action and its influence on the law. It is found that after adding nanomaterials to the system, it can interact with the water shutoff profile control agent by its physical and chemical properties such as small size and large surface area so that the stability, strength, and strength of the water shutoff agent can be improved. The temperature and salt resistance is significantly improved, thereby effectively improving the water shutoff rate and oilfield recovery rate. In addition, from the perspective of water shutoff agent research and development, various problems in current research in this area are pointed out, to provide a reference for the research and application of nanomaterials in water shutoff profile control agents.

The geometric model of a certain oil and gas mixed transportation pipeline was established with OLGA software, and the transient flow law during the pipeline shutdown and restart process was studied. First, the distribution characteristics of temperature, pressure and liquid holdup along the pipeline during steady state operation were analyzed, and the location of the minimum temperature and the location of the maximum pressure along the pipeline were determined. The influence of environmental temperature and shutdown time on operating parameters were analyzed. The safe shutdown time when the minimum temperature temperature is higher than its freezing point was determined. In the actual operation process, the shutdown time should not exceed the safe shutdown time, otherwise problems such as pipeline condensation and excessive starting pressure will easily occur, which threaten the safety of the pipeline.

An improved ethylene glycol method was used to efficiently synthesize silver nanowires with a diameter of about 130 nm, a length of about 150 μm, and L/D was about 1 150 by adjusting the content of chloride ions, the amount of polyvinylpyrrolidone (PVP) and the reaction temperature. All raw materials are put in one time before the reaction, no need to use syringe pumps and other equipment to strictly control the content of components. The synthesized silver nanowires have high purity and few impurities. At the same time, it was purified by filtration and washed twice to obtain extremely pure silver nanowires, which is suitable for large?scale production. The conductive network of silver nanowires was constructed on the quartz glass substrate by spin coating. The results show that the light transmittance at 550 nm is 95.5%, the sheet resistance is 52.0 Ω/sq, and it have excellent photoelectric properties.

With the increasing complexity of networked power systems, traditional control schemes are difficult to meet the actual needs. Bandwidth constraints, network security and actuator saturation have become important factors affecting the stability of power systems. An improved event trigger mechanism was introduced to improve the utilization rate of bandwidth resources for the problem of bandwidth resource limitation, and a new mathematical model of power system under deception attack and actuator saturation was constructed. Based on this number model, the sufficient conditions for the asymptotic stability of the power system were obtained by Lyapunov theory, and the design scheme of the security controller was given by using linear matrix inequality technique. Finally, an example of power system was given to illustrate the effectiveness of the proposed scheme.

In this paper, the heat treatment process of carburizing and quenching of 20CrMnTi steel gear was simulated by DEFORM?HT software, and the carbon mass fraction change from the surface layer to the core after carburization was obtained. The changes in the martensite structure after quenching were analyzed, the residual stress after quenching was analyzed, the appropriate quenching cooling medium was selected, and the metallographic structure and the Rockwell hardness from the surface to the core were measured through experiments. The results show that the metallographic structure and Rockwell hardness are in good agreement with the simulation results, which have certain guiding significance for production.

HP?MOF?74(Mg _x Ni_1-x ) (x=0.25, 0.50, 0.75) was synthesized by solvothermal method with Mg and Ni as central metals and sodium dodecylbenzene sulfonate (SDBS) as template. Using flue gas CO₂ and N₂ as adsorbents, the performance of HP?MOF?74(Mg _x Ni_1-x ) in adsorption and separation of CO₂/N₂ at 273 K and 298 K was investigated, the isotherms of CO₂ and N₂ on three different HP?MOF?74(Mg _x Ni_1-x ) materials were measured at 273 K and 298 K by static volumetric method, and the experimental data sets were fitted by Dual Site Langmuir Freundlich (DSLF) and Single Site Langmuir Freundlich (SSLF) models. The adsorption selectivity of CO₂/N₂ binary mixture was estimated according to the Ideal Adsorption Solution Theory (IAST). In addition, the isosteric heat of adsorption (Q_st) was calculated using the Clausius Clapeyron equation. The results show that the CO₂ adsorption capacity of HP?MOF?74(Mg_0.50Ni_0.50) sample is 4.864 mmol/g at 273 K and 100 kPa; the adsorption isotherms of CO₂ and N₂ on HP?MOF?74(Mg _x Ni_1-x ) are in good agreement with Dual Site Langmuir Freundlich (DSLF) and Single Site Langmuir Freundlich (SSLF) models respectively, indicating that the adsorption behavior of CO₂ is double sites adsorption, while the adsorption behavior of N₂ is single site adsorption; at 273 K and 100 kPa, the IAST adsorption selectivity of HP?MOF?74(Mg_0.25Ni_0.75) for CO₂ is 2 263, and the adsorption capacity and selectivity are better than those of traditional adsorbent MOF?74; the CO₂ isosteric heat of adsorption on HP?MOF?74(Mg _x Ni_1-x ) is higher than that of N₂, indicating that the surface free binding energy of CO₂ on HP?MOF?74(Mg _x Ni_1-x ) is higher.

With the rapid economic development, the demand for energy continues to increase, and the emission of CO₂ gas keep growing. The electrochemical reduction of carbon dioxide (ERC) to fuel and chemicals is an effective way to realize the conversion and utilization of CO₂ as well as the storage of renewable energy. Cu?based catalysts are one of the materials which can directly reduce CO₂ to high value?added chemicals(such as hydrocarbons) with high efficiency. Thus, the Cu?based catalysts have been one of the research focus of ERC technology research. The main research progress of Cu?based catalysts for ERC technology in recent years is reviewed. Firstly, reaction principle of ERC and the technology challenge are summarized, and then the cooperative control strategy for the structure and composition of copper?based catalysts is discussed for monometallic copper?based catalysts, polymetallic copper?based catalysts, copper oxide and oxide?derived copper catalysts, and copper?organic composite catalysts. In addition, research progress and unsolved problems of Cu?based catalysts are also summarized. Finally, the future trend these catalysts is also prospected.

In recent years, the sales volume of the automobile industry, which is the backbone of the national economy, has been declining, and the financial leverage ratio has continued to rise. In order to improve the profitability of automobile manufacturing enterprises, this paper used SPSS 26.0 and Excel 2010, collected the financial data of 145 auto A?share listed companies in Shanghai and Shenzhen from 2017 to 2019 as samples to conduct an empirical analysis and test of the relationship between corporate leverage ratio, corporate growth ability and profitability. The results show that there is a negative correlation between leverage ratio and profitability, positive correlation between corporate growth ability and profitability, negative correlation between corporate leverage ratio and growth ability, and there is a certain intermediary effect in the influence of corporate growth ability on profitability.

Chiral oxazolines are a type of important chiral heterocycles compound, which are not only present in many biologically active natural products and drug small molecules with physiological activity, but also in chiral cofactors and chiral ligands often used in chiral synthesis. Currently, the asymmetric synthesis of chiral oxazolines still relies on the condensation between chiral amino alcohols and carboxylic acid derivatives. However, due to the limited availability of chiral amino alcohols and the tedious synthetic route, the development of highly efficient and straightforward methods for chiral oxazolines synthesis via asymmetric catalysis is of significant synthetic value. In this paper, we have summarized the recent advances in the asymmetric catalytic synthesis of chiral oxazoline derivatives through transition metal catalysis and organocatalysis, including asymmetric Aldol reactions, asymmetric clizations and others.

The Finite Element Method was used to study the flow field of different screw combination sections of single?screw extruder. The Polyflow software was used to calculate the pressure field, shear rate field, velocity vector, mixing index and other parameters of the flow field of ordinary screw, ordinary screw and pineapple head combined screw, ordinary screw and pin combined screw. The post?processing results were compared and analysed.The results show that the ordinary threaded screw can provide a greater axial velocity for the fluid; although the pineapple head screw has greater resistance, the more oblique section design can provide better axial and circumferential velocity for the fluid; the barrier effect of the screw causes a part of the fluid to flow back. The three new types of screws can effectively stretch and shear the fluid while providing a good linear velocity for the fluid to make its dispersion and mixing more uniform. According to the analysis of the curve results, the mixing effect of pin?screw is the best.

A modified dicyandiamide?formaldehyde decolorizing flocculant was prepared using cyclohexylamine as modifier, and was used to simulate dye wastewater decolorization, flocculation and sedimentation experiments. The effect of reaction temperature, reaction time, material molar ratio and other factors on the decolorization performance of the modified flocculation was studied. The results show that reaction time is 3.5 h, reaction temperature is 85 ℃, material molar ratio of dicyandiamide to formaldehyde to ammonium chloride to cyclohexylamine is 1.00∶3.00∶0.50∶0.15, the decolorization rate 88.6% is achieved at a modified flocculant dosage of 100 mg/L. The decolorization and flocculation performance of the dicyandiamide?formaldehyde modified decolorizer is obviously better than that of the unmodified product.

Electrospinning is a fiber manufacturing process in which polymers are drawn and spun under the action of a high?voltage electrostatic field. This method has been widely used in material chemistry due to the simple preparation, low cost as well as easily available of micro?nano?scale fibers. In this paper, a polysulfur high?nucleus caged compound (Co₄₈) constructed by thiacalixarene was used as the loading material, and polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) blend (PAN/PMMA) was used as the spinning support, Co₉S₈ nanoparticles loaded carbon nanofibers (Co₉S₈@CNFs) were prepared by electrospinning technique. Composite nanofibers were prepared by spinning carriers with PAN and PMMA mass ratios of 10∶0, 7∶3 and 5∶5, respectively, and the carbon nanofiber composites obtained after heat treatment were used as electrode materials for the study of lithium?ion battery materials. The addition of PAN and PMMA has a positive effect on the electrochemistry of the final product compared to the calcined product of Co₄₈ crystals. The composites fabricated from PAN and PMMA presented high specific capacity，good cycling stability and rate capability.

The finite element model of the bolt flange washer was established, and the fastening experiment of the DN500 bolt flange connection system was carried out to verify the rationality of the finite element model. By controlling the width of the nut washer and the medium pressure of the pipeline, the effect of adding the nut washer on the stress distribution on the washer and bolt was compared and analyzed. It was found that adding a reasonable sized nut washer can not only increase the contact area between the nut and the flange surface and increase the compressive stress on the gasket, but also in the case of high bolt pre?tightening load and medium pressure. Prevent the bending deformation of the bolts and the pressure failure of the washers, increase the service life of the bolts, and improve the overall sealing performance of the bolt flange connection system.

Aiming at the problem that the existing online life prediction of lithium?ion batteries based on the correlation vector machine has a single consideration factor, which results in unsatisfactory prediction accuracy, a method based on principal component analysis (PCA) for weighted construction of characteristic factor variables was proposed. In this method, a variety of characteristic factor variables are taken as the research object to find the matrix of the score vector after the linear transformation. The feature coverage degree of different score vectors to the original variable data matrix is analyzed, and the corresponding feature vectors are constructed by weighted fusion. Using the vector as input, a prediction model is established by the relevance vector machine and the online prediction of lithium?ion battery life is performed, and the prediction results are finally obtained. International public battery data was used as the research object, and MATLAB experiments were used to verify that the method has the feasibility of multivariate prediction of battery life, and the prediction effect is better.

The aero?engine clamp has an assembly constraint relationship with the pipeline, and its layout position has an important influence on the direction of the pipeline and the vibration performance. An optimization method of engine clamp position adjustment based on improved Grey Wolf Optimization (GWO) was proposed. Based on the existing pipe?clamp geometric layout scheme, this method takes the adjustment of the natural frequency of the pipe?clamp to avoid resonance as the main optimization goal, takes the pipeline obstacle avoidance and the pipeline?clamp meeting assembly constraints as constraints, and applies the improved GWO algorithm to carry out the secondary optimization and adjustment of the clamp position. In order not to affect the geometric layout of the pipeline, an optimized space for the position of the clamp based on the pipeline projection line was established. In order to improve the efficiency of optimization calculation, the Kriging surrogate model reflecting the position of clamp and the natural frequency of pipeline was established to replace the time?consuming finite element calculation program in the optimization process. In order to improve the search performance of GWO, a GWO algorithm with improved convergence factor was proposed. This method can optimize the position of the clamp under the premise of ensuring the fine adjustment of the pipe geometric layout, and can ensure that the pipe and clamp meet the assembly constraints. Finally, the effectiveness of the proposed method was verified by the test function example and the clamp arrangement example.

To investigate the structure?function relationship of novel extended surfactants and the mechanisms of reducing interfacial tensions (IFTs) at oil?water interface, the interfacial tension values of 13?P series 13?P（I?C₁₃（PO） _x S,x=5,10,15,20）with different concentrations of NaCl and n?hexane to n?tetradecane at fixed concentration were measured by rotary drop interfacial tension meter. The result indicates that at higher numbers of PO（x=15,20), the n_min values become higher with increasing concentration of NaCl. At lower numbers of PO（x=5,10), the n_min values become lower with increasing concentration of NaCl. It reflects two mechanisms on reducing IFTs: Hydrophilic lipophilic equilibrium effect and hydrophilic hydrophobic group in size matching effect, both of which work together, and the size matching plays a crucial role at lower numbers of PO and HLB dominates at higher numbers of PO.

The dust removal characteristics and working mechanism of the current four major types of dust collectors were reviewed. It mainly focused on electrostatic precipitator technology, introduced its research status at home and abroad in recent years, analyzed the influence of many different factors (equipment structure parameters, gas characteristics, dust properties) on the efficiency of electrostatic precipitator equipment, and summarized electrostatic precipitator. The current technical shortcomings of the collector: The selection of the discharge electrode, the optimization of the best parameters, the anti?corrosion and cleaning of the dust collecting plate. In the future, the following issues should be focued on: development of discharge electrode materials suitable for new forms of electrostatic precipitators, discharge characteristics and dust removal efficiency in complex atmospheres, reduced insulation performance at the dust collector, and corrosion protection.

Taking advantage of its high?speed and high?precision characteristics, cooperative robots can improve production efficiency by imitating human creative and complex actions. At present, the simulation of human action mainly comes from the long?term debugging of the deployment personnel, which is lack of general solutions and can′t be deployed quickly. Based on this, an anchor?free RepVGG network?based Siamese network collaborative robot target tracking algorithm was proposed. The algorithm consists of a siamese network module, a classification regression module and a robot execution module. The siamese network module used the improved RepVGG network instead of ResNet as the backbone network to extract image features, which can improve the running speed of the whole network without losing accuracy，reduce the hardware requirements and is more friendly to special deep learning chips; the classification and regression module introduced the centrality branch to improve the prediction accuracy of the center point of the tracking frame; the robot execution module uses scale penalty and aspect ratio penalty to smooth the tracking boxes and ensure the smooth operation of the collaborative robots. Experimental results show that the average rate is 14 FPS higher than that before replacing the backbone network, which realizes real?time object tracking.

According to the characteristics of the canteen, the FLACS software was used to build a three?dimensional model for a university canteen. On the basis of considering the jet direction, obstacles and other factors, the leakage and explosion of natural gas were simulated, and the diffusion process of gas cloud, the development law of explosion shock wave and temperature in a specific scene were studied. The results show that when the gas leaks vertically upward, the gas accumulates in the small booth due to the obstruction of the canteen roof. When the natural gas leaks horizontally, the volume fraction of natural gas cloud in the dining area is higher. At the initial stage of the explosion, the explosion pressure shock wave centered on the ignition point first appears, and the pressure shock wave travels outward in a circular arc. The leakage direction has little effect on the maximum over pressure generated by the explosion.The temperature distribution is greatly affected by the direction of leakage. When vertical injection is carried out, the high temperature is concentrated in the small booth. When horizontal injection is carried out, the temperature is distributed from high to low.

The cold flow property of biodiesel can be effectively improved by pour point depressants (PPD). The terpolymer (AHM) was prepared by solution polymerization of hexadecyl methacrylate, hydroxyethyl methacrylate and maleic anhydride. The effect of AHM on pour point reduction of biodiesel was also investigated. The hexadecyl methacrylate and AHM were characterized by infrared spectroscopy. The optimal reaction conditions of AHM were determined by single factor experiment: n(hexadecyl methacrylate)/n(hydroxyethyl methacrylate)/n(maleic anhydride)=2∶1∶2, the initiator mass fraction is 3.0%, the solvent mass fraction is 65%, the reaction time is 3 h, and the reaction temperature is 85 ℃. When the mass fraction of AHM is 0.7%, the freezing point of biodiesel decreased by 12 ℃. The morphology of wax crystals precipitated from biodiesel at low temperature after adding pour point depressant was observed by polarizing microscope, and the morphology was more uniform and dense.

In view of the current situation that independent automobile brands are big but not strong in the domestic market, this paper took Chinese independent automobile brands as the research object, analyzed the consumption psychology of Chinese consumers, and discusseed the influence of brand cognition, customer experience, perceived novelty, perceived practicality and friends' recommendation on brand advocacy, and with customer purchase intention as the mediating variable, the structural equation theory was used to construct, test and revise the model, and the hypothesis test was carried out. The results show that customer experience, perceived novelty and friends' recommendation can directly promote customers' purchase intention and brand advocacy, while perceived practicality can indirectly promote brand advocacy, while brand cognition can only directly promote brand advocacy. Purchase intention plays a mediating role among customer experience, perceived novelty, perceived practicality, friends' recommendation and brand advocacy,but does not play an intermediary role between brand cognition and brand advocacy..

The pollution of water is becoming more and more serious, and photocatalytic degradation of pollutants in water by sunlight plays an important role in the future development. A simple chemical precipitation method was introduced. CNTs were compounded on the surface of Bi₁₂O₁₇Cl₂ to obtain a series of CNTs/Bi₁₂O₁₇Cl₂ composites. The structure, morphology and optical properties were measured and characterized by XRD, TEM, UV?Vis DRS and PL. The results show that compared with single?phase Bi₁₂O₁₇Cl₂, CNTs/Bi₁₂O₁₇Cl₂ composites show excellent pollutant degradation activity and good photocatalytic stability and cycling performance. It is found that superoxide radical (·O {}_{\mathrm{2}}^{-} ) and hole (h⁺) are the main active species through trapping experiments, and the possible degradation reaction mechanism is speculated. This study provides a cheap and simple modification method for improving the photocatalytic performance of the catalyst, and has a certain guiding role in the synthesis of other high efficiency photocatalysts.

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.

In order to improve the accuracy of gasifier risk assessment, a safety assessment method that combines cloud model with catastrophe progression method was proposed. Through literature review and expert analysis, the risks of the gasifier are divided into mechanical systems, personnel, management and environmental risks, and a multi?level risk assessment system for the gasifier was established. The cloud model is an effective tool for qualitative and quantitative conversion. The entropy and hyper?entropy feature values of the cloud model were introduced, and the cloud entropy weight method was proposed to improve the traditional weight calculation method, and the weight calculation of all indicators was carried out to improve the accuracy of the ranking results. According to the normalization formula, the mutation membership value of each layer index and the total mutation membership value of the gasifier are calculated, and the risk level of the gasifier is judged according to the risk level evaluation table. The research results show that this method improves the comprehensiveness and objectivity of the weight ranking, and makes the gasifier risk assessment results consistent with the actual situation, which verifies the feasibility and effectiveness of the method.

In this paper, the method of combining Grand Canonical Monte Carlo simulation and Ideal Adsorption Solution Theory was used to study the adsorption performance of CO₂ and CH₄ on NaX zeolite. By comparing the fitting results of simulation data under different adsorption theoretical models and calculating the adsorption heat, a description of the adsorption and separation process of CO₂ and CH₄ gas was obtained. The results show that the adsorption strength of CH₄ molecules is weaker than that of CO₂ molecules, and its adsorption is closer to the ideal adsorption. The adsorption selectivity of CO₂ molecules is decreases with the increase of its content in the air, and decreases with the increase of temperature under low pressure conditions. Therefore, low temperature and low pressure are more conducive to the separation of CO₂ molecules.

A novel distributed model predictive control (DMPC) approach based on immune algorithm (IA) to find out the optimal system decomposition structure is proposed. The IA is used to solve decomposition problems for input clustering decomposition (ICD) and input?output pairing decomposition (IOPD), which can minimize the impact of input?output coupling between systems, and then DMPC algorithm is used to control the decomposed system. This approach effectively reduces the coupling between subsystems, and reduces the communication load of the system. Finally, a heavy oil fractionation chemical process is simulated and compared with the centralized MPC simulation results to verify the effectiveness of the algorithm.

Proton conductive materials are an important part of sensors and fuel cells. In recent years, the research of crystalline proton conducting materials has mainly focused on metal organic framework material(MOF). Lanthanide metal organic framework (Ln?MOF) is an important member of the MOF family, and it is easy to form a stable and diverse framework owing to the strong coordination ability, Lewis acidity and complex functionality of lanthanide ions. At present, people are beginning to focus on its research in the field of proton conduction. This article reviews the research progress in proton conduction of Ln?MOF materials with different functional acid groups (carboxylate, phosphonate or sulfonate groups, etc.) introduced into the main frame. The challenges faced by Ln?MOF materials in the study of proton conduction were prospected.

In this work, the inner and outer loop control strategy is adopted for the unmanned aerial vehicles (UAVs) formation system. Firstly, a sliding mode control method based on memory event?triggered mechanism (METM) is proposed for the position subsystem under delay and disturbance. The second?order model is established for each UAV, and the leader?follower framework is adopted to realize the desired flight formation. Secondly, an adaptive METM is proposed to alleviate the transmission burden, in which control input feedback is introduced. For the resulting communication delay of the control input in the proposed METM and the external disturbance to the system, a sliding mode controller is designed, which maintains desirable control performance and solves the influence of communication delay and bounded disturbance to a certain extent. Thirdly, the stability of the closed?loop system is proved by applying Lyapunov theory and H_∞ control theory, and a method that facilitates solving controller gain and triggering parameter through a series of linear matrix inequalities (LMIs) is proposed. Moreover, based on the obtained virtual control quantity, a tracking controller is designed for the attitude subsystem. Finally, a simulated example is exploited to verify the effectiveness of the proposed method.

In order to improve the balance between invisibility and robustness of image watermarking, a color image watermarking algorithm is studied by using wavelet transform and Heisenberg array decomposition （HAD） singular value decomposition （SVD）. Firstly, the host image and watermark image are transformed through color space color space, then the host image is transformed by wavelet transform, then the low frequency coefficients are decomposed by HAD and SVD, and the watermark is embedded after SVD in the low frequency. The experimental results show that the proposed watermarking method has strong robustness against multiple watermarking attacks, which is reflected by the normalized correlation NC of the objective evaluation criteria of extracted watermarks. The host image has good invisibility after embedded watermark, which is reflected by objective evaluation standard peak signal?to?noise ratio （PSNR） and structural similarity of images （SSIM）. It can embed grayscale or color large watermark with strong ability of embedding information. It is concluded that that the watermarking method has a certain application value.

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.

Based on the study of the material dissolution mechanism,it was clear that uniform solubility and controllable solubility were the key properties of soluble materials.Dissolvable magnesium and aluminum metal material were designed. The test results of the sample show that the designed dissolution rate of a dissolvable materials is 0.184 g/h under the conditions of 1% Cl- mass fraction of the solution and a temperature of 90 ℃. The advantages and disadvantages of bridge plug structure design at home and abroad were compared, based on the concept of dissolution difference and the objective of optimizing pressure bearing, anchoring and dissolution performance, a new dissolvable bridge plug, which meet the fracturing demand of Liaohe Oilfield, was developed. The results of indoor evaluation tests show that, the fracturing ball can be dissolved in 30.0 hours under the conditions of 1% Cl- mass fraction of the solution and a temperature of 90 ℃;the maximum working pressure of the dissolvable bridge plug is 70.0 MPa, the effective sealing time is more than 12.0 hours, and the dissolution time is 16.0 days. The field test was carried out with the developed dissolvable bridge plug. During the field test, the setting and releasing operation was successful, and the soluble ball was obviously in place. The bridge plug has been dissolved after 18.0 days of spraying. The successful development of dissolvable bridge plug will provide important supports for the large⁃scale volume fracturing technology in Liaohe Oilfield.

High?nuclear silver clusters have recently received increasing attention owing to their interesting electronic structures and diverse geometric structures. According to Lewis acid?base theory and coordination chemistry theory, silver ions, as acidic centers that provide empty orbitals, often combine with organic ligands that carry lone pairs of electrons as basic centers to form stable coordination compounds. Alkynyl, thiol, and organic phosphine ligands have been widely used to coordinate with silver(I) ions to form silver clusters with various structures. This paper introduced the research progress of the silver chalcogenide clusters constructed by tert?butyl mercaptan ligand, as well as the synthesis methods and structures of silver chalcogenide clusters with different configurations, and explored its potential luminescence and electrochemical properties. The application prospects and development directions of silver chalcogenide clusters was prospected.

In order to obtain good performance and required goals, the existence of asynchronous switching of controllers and subsystems must be considered. The event?triggered control of nonlinear switched system under asynchronous switching is studied. As the switching of the controller lags behind the switching of the subsystem, asynchronous behavior occurs. First, the switched nonlinear systems with linear parts and nonlinear parts are researched and the Laypunov functions are constructed. Then, a switching controller for a cascaded nonlinear switched system to obtain a closed?loop system is designed, and the average dwell time is given to get the sufficient condition for the switched system to be globally uniformly and exponentially stable. Finally, a numerical example is given to illustrate the feasibility of the method.

For a long time, researchers mostly analyze the transmission process of infected nodes in complex networks to get the target of forecasting and arresting the extend of the infectious diseases. In this article, the SEIR propagation dynamics model was extended to the undirected and powerless large small world network, and the weights between nodes were given as infection ability. Two initial node selection methods were selected to carry out multiple simulation experiments. Based on the traditional method of judging the impact of transmission by the number of infected people and infection threshold, the specific values of infection probability, peak value and inflection point time were added to analyze the impact of initial node selection on transmission process more comprehensively. The compared experimental results show that the initial node which the degree is larger and the betweenness is larger, the larger the propagation scale, the faster the propagation speed and the shorter the equilibrium time. This study provides some reference value for guard against and control of the extend of infectious diseases.

Aiming at the low efficiency of Apriori algorithm in scanning database and low dimensional frequent itemset, an efficient implementation method of Apriori algorithm was proposed, which is called EI_Apriori algorithm. This method utilizes the vector?based storage structure and pre?pruning to reduce the number of scanning databases and low?dimensional frequent itemsets and thus improves the efficiency of the Apriori algorithm. According to the actual situation of student achievement analysis, the constraints on the sequence relationship between courses are added in the association rule mining, and the constraints on the score level range are added in the association rules. The adjusted EI_Apriori algorithm was applied in score association analysis. The results show that the EI_Apriori algorithm can accurately find the association rules that meet the real needs, which proves the superiority of EI_Apriori algorithm.

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.

Ozone is a clean and strong oxidant, which has been widely used in the degrading of organic pollutants. However, the ozone oxidation process alone is not ideal for the treatment of difficult?to?degrade organic pollutants in water. Therefore, ozone catalytic oxidation technology came into being, and the selection of catalyst is the key factor to determine its degradation effect. Based on the various types of catalysts, the mechanism of metal oxides, carbon?based materials and supported composite catalysts for the catalytic oxidation treatment of water pollutants by ozone was reviewed. The existing problems and the main problems that need to be solved at present were analyzed to provide theoretical basis and reference for the research and development of suitable catalysts.

In this work, the HTO (H_4x/3Ti_2-x/3□ _x/3O₄·nH₂O) was used as the precursor raw material, and the nanoscale titanium oxide particles (ST01) were loaded on the surface of the HTO by water bath impregnation, and the TiO₂ homogeneous structure composite was topologically synthesized by calcination method. Using X?ray diffraction （XRD）, Raman spectroscopy (Raman) and other testing methods, the effect of calcination temperature on the phase transition process with titanium dioxide was studied in detail. The results indicate that the HTO can transfer to TiO₂（B）, anatase TiO₂ and rutile TiO₂ with increased temperatures, and the TiO₂ homophase composites are obtained with various structure and content of TiO₂. The degradation experiment was carried out with Rhodamine B （RhB） as the pollutant model. The photocatalytic activity of the sample at 600 ℃ is significantly higher than that of other samples, mainly because the separation efficiency of electrons and holes of the sample is the highest at this time, indicating that the structure and composition of homogeneous composite TiO₂ affect its photocatalytic activity. In addition, dye?sensitized solar cell （DSSCs） experiments show that the reason for the higher optoelectronic performance of the samples at 600 ℃ is that the two?dimensional sheet?like morphology facilitates the rapid migration of photogenerated carriers.