The paper aims to study the problem of obstacle avoidance in air?ground cooperative tracking control for the unmanned aerial helicopter (UAH),in which a new approach of designing the path obstacle avoidance plan and controller design is proposed.Initially, as for the uncertain linear UAH,by processing and judging two?dimensional environmental information within the warning range for the UAH,an obstacle avoidance strategy is proposed with the help of wall?following algorithm,and the flight angle of obstacle avoidance path and the tracking speed that can make up for bypass distance are calculated.Secondly,the proposed obstacle avoidance method is extended to the three?dimensional case,and the flight angle of the UAH is determined based on the obstacle information in the horizontal and vertical directions,which can reduce the bypass distance caused by the obstacle avoidance link as possible.Thirdly,based on two derived obstacle avoidance algorithms above,the artificial neural network (ANN) is introduced to estimate model uncertainty,and then the tracking control design schemes are established by using feedforward compensation and optimal control technologies.some simulations demonstrate the effectiveness of the proposed obstacle avoidance strategy and control algorithm.

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 COVID?19 epidemic is facing the influence of a variety of complex practical factors, which makes the development of the epidemic uncertain. In order to overcome the problem of large error in epidemic forecasting results due to the limitations of many ideal assumptions based on the infectious disease compartment model, a time series forecasting model based on deep learning is adopted to predict the epidemic development, and an informer model based on transformer model is established. Attention mechanism and distillation mechanism are applied to the time series forecasting of epidemic data. The threshold autoregressive (TAR) model and a variety of mainstream recurrent neural time series prediction models are used as comparison models. Through simulation experiments, the current number of remaining infections in the epidemic data of China, America and Britain is predicted in the short term, and RMSE and MAE are used as evaluation indicators, and then the best model is selected for medium ? and long?term prediction. The experimental results show that the indicator value of the informer model is optimal in both RMSE and MAE, further indicating that the prediction accuracy of the informer model is higher than that of other comparative models in China, America and Britain. Finally, the Informer model is used for the development of the epidemic in China，America and Britain medium and long?term prediction.

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.

With the improvement of environmental uncertainty, the demand for supply chain stability of petrochemical enterprises in China is rising day by day. The evaluation of supply chain resilience of petrochemical enterprises has become an important means to judge the risk coping ability of petrochemical enterprises. This paper constructs a supply chain resilience evaluation index system in the petrochemical enterprises. And fuzzy analytic hierarchy process and BP neural network are used to evaluate the toughness strength of petrochemical enterprise supply chain, so as to determine the toughness level of petrochemical enterprise supply chain.It is found that the strength of supply chain toughness of petrochemical enterprises is uneven, and the overall level of supply chain resilience is low. On the basis of the research results, some practical suggestions are put forward for the forging of resilient supply chain in petrochemical enterprises.

Magnetic tomography method has been widely used for nondestructive external inspection of buried and submarine pipelines, which is based on the principle of metal magnetic memory to discern the danger level and location of the stress concentration zone by measuring the anomalies in the spatial magnetic field distribution outside the pipeline. The distribution characteristics and spatial propagation law of pipeline inspection signal detected by magnetic tomography method, the energy distribution and change law of spatial magnetic memory signal in the stress concentration zone of magnetized pipelines are studied in this paper. The magnetic dipole field is used to establish the magnetic field model in the stress concentration zone of the inner wall of the pipeline, and the magnetic energy and energy density of spatial magnetic memory signals under different lift?off values outside the pipeline are finite element calculated based on the magnetic energy theory to derive the distribution law of spatial magnetic field and the correlation of magnetic energy density of magnetic signals under different lift?off value is analyzed. The results show that the spatial magnetic field energy outside the pipe decays with the increase of lift?off value, and the decay is the fastest within the distance of 50 mm from the outer wall of the pipe to the physical force; the correlation of magnetic energy density of different lift?off values shows that the magnetic signal detected by magnetic tomography method outside the pipe is homologous with the signal in the stress concentration zone of the inner wall of the pipe. Theoretically, it explains the effectiveness of magnetic tomography method and also provides evaluation indexes for extracting effective signals from the detection data.

Li₂ZnTi₃O₈ (LZTO) anodes of lithium?ion batteries have been prepared by a sol?gel method. The effects of the calcination temperature and time on the electrochemical performance have been studied for LZTO in detailed. The optimum calcination temperature and time are 700 ℃ and 3 h, respectively. On the basis of the optimum preparation process, citric acid as the chelating agent has been introduced into the synthesis to modify LZTO. When the molar ratio of metal ions to citric acid is 2.00∶1.50, the obtained product is denoted as LZTO?2/1.50, which has small particle size, good dispersion, and then shows good electrochemical performance. The discharge specific capacity is 203.6 mA·h/g after 300 cycles at the current density of 0.5 A /g for LZTO?2/1.50.

The data of chemical processes often contains dynamic timing characteristics, and traditional fault detection has low usage of dynamic information, which limits the fault diagnosis performance. To address this problem,a new method of chemical process fault diagnosis based on an attention?enhanced encoder?decoder network model (AEN) was proposed. The coding part uses the LSTM to extract the feature information of the process data and combine it with the attention mechanism to utilize the dynamic information among the process data more effectively； the decoding part uses the LSTM and combines the context vector provided by the attention mechanism to provide more accurate state information for the softmax regression, and finally, the softmax regression is used to obtain the probability value of the fault category for each sample data. The introduction of the attention mechanism improves the efficiency of the model in using process dynamic information in the time domain. The proposed method is experimented with using Tennessee Eastman process data and compared with the results of standard PCA?SVM, DBN and ResNet, and the results show that the proposed method is more effective in diagnosing faults.

Thiacalix[4]arene ligands have the advantages of high recognition, derivatization, excellent stability and other advantages. Lanthanide (Ln) ions can coordinate with thiacalix[4]arene ligands to form multi?functional coordination clusters, which received increasing attention due to their unique catalytic, magnetic, optical properties. Thiacalix[4]arene can sensitize Ln ions to luminescence by the coordination of phenol and S groups via the "Antenna effect". This paper reviewed recent advances in structures, luminescent properties, and applications of luminescent Ln?thiacalix[4]arene complexes.

The Fe/Mo ordering at B?sites of Ba₂FeMoO_6-δ (BFM) were changed by adjusting Fe/Mo amount of substance ratio (i.e., stoichiometric ratio), and then a new double?perovskite anode material Ba₂Fe_1.3Mo_0.7O_6-δ (BFM_0.7) for SOFC were obtained. The results indicated that the electrical conductivity of the BFM_0.7 anode is 15.0~20.0 S/cm at 600~800 ℃ in H₂, which is much larger than that of the lowest target for SOFC electrode (0.1 S/cm). The peak power density and polarization resistance of the BFM_0.7 anode cell attained 1 149 mW/cm² and 0.15 Ω·cm² at 850 ℃. Compared with BFM anode, the performance of BFM_0.7 is significantly improved. In addition, the performance of BFM_0.7 anode cell showed no degradation after testing for 39 h, indicating that the BFM_0.7 anode possesses has excellent electrochemical stability.

Monolayer Janus transition metal disulfides have low dimension, high mobility, and peculiar electronic structure properties, which have potential applications in electronics and optoelectronic devices. In devices made of monolayer Janus transition metal disulfide and substrate materials,are usually stressed due to lattice mismatch between monolayer Janus transition metal disulfides and substrate, it is significant to study the strain effect on physical properties of monolayer Janus transition metal disulfides through Raman scattering.This paper systematically investigate the biaxial strain effect on the atomic structure, electronic structure and Raman spectra of monolayer Janus MoSSe. The results show that monolayer Janus MoSSe can exhibit a band gap transition from direct to indirect one under biaxial strain, due to both the energy shift of bonding orbitals between the top of the valence band and the bottom of the conduction band and the sensitivity to strain. This paper also thoroughly study the strain effect on the Raman shift and intensity of monolayer Janus MoSSe. It is found that under biaxial strain modulation from decreasing compressive to increasing tensile, for the Raman shift, the three peaks of E¹, E², and A {}_{\mathrm{1}}^{\mathrm{1}} red?shift, while the peak of A {}_{\mathrm{1}}^{\mathrm{2}} blue?shifts abnormally with decreasing compressive strain; for the intensity, the peak intensity of the doubly?degenerate modes (E¹,E²) increases monotonically, while singly?degenerate modes shows the opposite trend, except for the A {}_{\mathrm{1}}^{\mathrm{1}} which intensity decreases with decreasing compressive strain and then increases with tensile strain. This paper propose a simple model to comprehend the strain effect. This theoretical study may supply an effective means to quickly and quantitatively characterize the strain size and type in Janus materials through the frequency difference and intensity ratio between typical Raman peaks.

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.

In view of the irregularity of the bottom floor of working face and the diversity of the shape of the flying gangue in steeply dipping coal seam, based on the geographic information system data such as contour line of bottom floor of working face, the 3d grid model of bottom floor is established, combined with the energy tracking method(ETM) C + + programs, four typical shapes of flying gangue with the same mass and different shapes are simulated to obtain the motion trajectories of the migration of flying gangue in the actual working face, as well as the velocity, angular velocity and energy change curves at any time. The influence of the shapes on the motion of flying gangue is analyzed. In order to verify the accuracy and feasibility of the method in this paper, the trajectory simulated by Rockyfor3D software is compared. The results show that the transport capacity of ellipsoidal flying gangue is much higher than that of polyhedral flying gangue. Compared with common polyhedral flying gangue, the regular polyhedral flying gangue has farther migration distance and less energy loss due to collision. The number of edges of flying gangue of regular polyhedron is inversely proportional to the energy loss of flying gangue in collision, which indicates that flying gangue of regular polyhedron with multiple edges is most likely to cause danger．

Pollution caused by petroleum?based plastic products has become a problem that is difficult for human beings to solve, and the existing treatment methods are both energy?consuming and easy to cause secondary pollution. The study found that the bacteria that degrade plastic in the intestines of Galleria mellonella (Lepidoptera: Pyralidae) larvae can effectively accelerate the degradation of plastics. This experiment uses polystyrene (PS) packaging boxes, which are common in life, as the only food source to feed the larvae of the large wax borer, enriching the PS?degrading bacteria in the intestines of the G. mellonella larvae. After dissection, culture, and isolation, four strains were obtained: PD?1, PD?2, PD?3 and PD?4. The degradation capacity of MSM culture medium with PS film as the only carbon source was inoculated with each strain, and the degradation rate of PD?1 on PS film was the highest, which was 1.8%. PD?1 was observed by strain morphology, physiological biochemical determination and phylogenetic tree construction, and it was identified as Enterobacter colebella (Klebsiella). Meanwhile, the method of UV and nitric acid pretreatment of PS film were used to improve the degradation rate of the strain, and the results showed that the weight loss rate of PD?1 degradation of nitric acid?treated PS film was improved, which was 2.5%, while the UV group was 0.8%, indicating that PS film was more easily degraded by PD?1 after nitric acid treatment.

Recognition of weather phenomena based on images is essential for the analysis of weather conditions. To address the problems that traditional machine learning methods are difficult to accurately extract various weather features and poor in classifying weather phenomena and the accuracy of deep learning for weather phenomena recognition is not high, a weather recognition model based on image block and multi?headed attention mechanism is proposed. The model introduces Swin Transformer into the field of weather recognition for the first time, and adopts a multi?headed attention mechanism combining window multi?head self?attention layer and shifted?window multi?head self?attention layer, whose regionally relevant features extraction capability makes up for the shortcomings of traditional methods and can extract complex weather features from images. The model is trained using transfer learning, and the fully connected parameters of the fine?tuned model are input to the Softmax classifier to achieve recognition of multi?category weather images with 99.20% recognition accuracy, which is better than several mainstream methods in comparison, and it can be applied to ground weather recognition systems as a weather recognition module.

Polylactic acid/Poly(butylene adipate?co?terephthalate)/Poly(methyl methacrylate)?b?poly (butyl acrylate)?b?poly (methyl methacrylate)ternary blends (PLA/PBAT/MAM) were prepared by melt blending, and the effect of MAM relative molecular weight on the morphology, structure and properties of the blends was investigated. The results showed that the addition of MAM block copolymer can inhibits the crystallization of PLA，improve the compatibility of PLA/PBAT, reduce the particle size of the dispersed phase and make the distribution more uniform, improve the impact properties and elongation at break of the blends. And the relative molecular weight of MAM increased, the impact strength and elongation at break of the blend increased, the smaller the size of the dispersed phase particles, and the more uniform of particle size distribution.

Gasoline molecular blending technology on?line requires rapid access to detailed molecular composition information of various types of component oils. In this paper, an autoencoder?based method for the rapid resolution of gasoline molecular composition is developed, which can directly predict the detailed monomeric hydrocarbon composition of gasoline from near?infrared spectra. The constructed autoencoder model of gasoline molecular composition can explore the potential features and recover the original molecular composition by decoding the potential features. The artificial neural network algorithm is used to correlate the NIR spectral information with the potential features of gasoline composition. The accuracy of the model is verified by using hydrogenated gasoline with the average absolute error is 0.033. The model developed in this work applies the current popular autoencoder algorithm to the traditional petrochemical process, which is an important guideline for blending online and real?time optimization of gasoline molecules.

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.

Billets have oxidized layers and defects on their surface due to the production process, so they must be surface?regulated by grinding. There is no special equipment for surface regrinding of large square steel billets; a square steel regrinding equipment was designed. Kinematic simulation verification was completed using ADAMS software. The results show that the regrinding equipment can simultaneously and smoothly complete the grinding operation on two adjacent surfaces. Using finite element software ANSYS to carry out stress analysis and modal analysis of the regrinding machine under load, and improve the structure; according to the simplified kinematic model, static analysis was carried out to get the required input driving torque, and the selection of the critical components of the spring was completed. Theoretical calculations and simulation results show that this regrinding machine can efficiently grind the surface of large square billets.

Aiming at the bond?slip behavior of reinforced concrete, the finite element model of reinforced concrete bond?slip based on cohesion model was constructed by ABAQUS finite element software. The mesh sensitivity and cohesion parameter sensitivity of the simulation model were explored by energy and load?displacement curves. Aiming at the problem of bond strength of reinforced concrete, a nonlinear autoregressive exogenous network (NARX) was developed to predict the load?displacement curve for reinforced concrete by creating 20 sets of data with the variables of bond length, reinforcement diameter, and loading method. The study shows that the mesh size of 6 mm provides an ideal balance between prediction accuracy and computational cost. Based on the sensitivity of the finite element prediction results, the cohesive parameters are in the sequence of damage initiation strength, fracture energy, and stiffness. The NARX with the prediction accuracy of 99.6% is promising to replace time?consuming numerical simulations and experimental works to achieve an efficient and accurate prediction of the bond strength of reinforced concrete. Such an efficient and accurate prediction method provides a novel and convenient methodology of predicting and designing the bond strength of reinforced concrete.

The direct method was used to prepare polyurea lubricating grease, and the effects of several different types of additives on the extreme pressure and anti?wear performance for polyurea lubricating grease were investigated and studied. The results demonstrate that several types of additives have good compatibility with polyurea grease, and they have little undesirable influence on colloidal stability of polyurea grease, and they can also enhance thermal stability of polyurea grease. Moreover, the addition of additives can significantly improve the performance of extreme pressure and wear resistance for polyurea lubricating grease. And in the experiments, it was found that the composite multifunctional additive containing sulfur and phosphorus has a relatively better effect on improving the extreme pressure and wear resistance of polyurea lubricating grease. The research results can provide a reference basis for the improvement of extreme pressure and anti?wear property for polyurea lubricating grease, achieving a relatively optimized comprehensive performance, thereby enhancing its practical utilization performance under the harsh working conditions for high load and high speed mechanical equipment.

In order to study the influence of cross?fracture on the mechanical properties and damage modes of deep shale, and better understand the damage evolution law of shale containing cross?fracture under high temperature and high pressure coupling, 15 groups of shale models containing cross?fracture with different inclination angles were established, and simulation experiments were carried out to study the stress?strain relationship, damage evolution and acoustic emission characteristics of the shale specimens. The results show that the compressive strength and modulus of elasticity of shale are negatively correlated with the inclination angle of the main cracks, and show an upward concave trend with the increase of the inclination angle of the secondary cracks, and the compressive strength of shale decreases significantly when there are cracks perpendicular to or close to perpendicular to the loading direction; the damage modes of shale specimens under the influence of cross?cracks are mainly divided into "X"?shaped damage, diagonal "N"?shaped damage, diagonal "W"?shaped damage, inverted "V"?shaped damage, damage along the main crack, "V"?shaped damage and "λ"?shaped damage; the fractal dimension of shale specimens is negatively correlated with the inclination angle of the main crack, and as the inclination angle of the main crack decreases, the value of fractal dimension tends to increase, and the corresponding damage pattern of the specimens is more complicated and the internal damage is more intense.

In order to understand the mechanism of CO₂ dissolved buried mechanism in high temperature and high pressure porous environment,physical simulation experiment was conducted to study CO₂ dissolved buried mechanism,mineralization buried mechanism and free buried mechanism in porous media by means of indoor physical model experiment.The results show that the solubility of CO₂ in formation water is mainly affected by temperature, pressure and salinity of formation water. CO₂ dissolved in formation water will mineralize with minerals in rocks, and the mineral content of rocks will change significantly before and after the reaction. The long core displacement experiment characterized the amount of free CO₂ storage and the oil displacement effect. The experiment reveal that CO₂ flooding in porous media has dual effects of burying and enhancing oil recovery.

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.

Using sludge from municipal sewage treatment plants as raw materials, sodium bicarbonate as green activator, and ammonium phosphate as nitrogen and phosphorus source, modified sludge biochar was prepared by vacuum pyrolysis. SEM and FT?IR were used to characterize and analyze the materials. The results show that the modified sludge biochar can significantly increase the specific surface area and porosity of the biochar, as well as the number of N-H and C-O. By changing the dosage of modified sludge biochar, pollutant mass concentration, reaction temperature and pH value and other conditions, the effect of modified sludge biochar on phenol adsorption was studied, and the adsorption process and mechanism were studied. The results show that the modified sludge biochar has a better adsorption effect on phenols, and the adsorption rate increases with the increase in the dosage of sludge biochar; when the pollutant mass concentration increases, the adsorption rate decreases; the higher the temperature, the better the adsorption effect; the acidic conditions are more suitable for the reaction. The adsorption process of modified sludge biochar for phenols conforms to quasi?second?order kinetics, and the adsorption mechanisms are monolayer adsorption and uneven surface adsorption. Modified sludge biochar has good recyclability and it can provide an effective way for the resource utilization of sludge and the treatment of phenols in wastewater.

Aerobic oxidative desulfurization is a safe and environmentally friendly desulfurization method, but oxygen usually needs to be activated under harsh conditions, the synthesis of efficient catalyst is an effective way to improve desulfurization activity. In this work, flower?like cobalt molybdate with large specific surface area was synthesized by one?step hydrothermal method using cobalt chloride and ammonium molybdate as raw materials. In addition, urea is used as precipitation agent and structure control agent. The morphology and structure of the CoMoO₄ were characterized by FT?IR, XRD, SEM, XPS and N₂ adsorption desorption techniques. Dibenzothiophene in simulated oil was removed using CoMoO₄ as catalyst and molecular oxygen as oxidant. The effects of reaction temperature, the flow of oxygen, the amount of CoMoO₄ and the type of sulfur compounds on the desulfurization rate were investigated. In addition, the recycling performance of flower?like CoMoO₄ was studied. The experiment shows that the desulfurization rate can reach 98.2% under the optimal reaction conditions. The catalyst can be reused for 5 times without significant reduction in oxidative desulfurization activity. The formation of superoxide radical in the oxidation desulfurization process resulting in high desulfurization activity.

A new type of Ruddlesden?Popper cobalt?rich layer perovskite oxide La_1.5Ca_0.5Ni_0.2Co_0.8O_4+δ (LCNC) was synthesized by a sol?gel process. The results show that the conductivity of LCNC in air at 400 ℃ to 800 ℃ is 4~58 S/cm, which is better than that of most reported SOFC cathode materials. The polarization impedance of symmetrical battery LCNC|LSGM|LCNC is 0.16 Ω·cm² at 800 ℃. The maximum power density of the single cell supported by 300 μm thick La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ (LSGM) with the LCNC cathode was 527 mW/cm², and the performance of the single cell decreases slightly after working continuously for 50 hours. The experimental results show that LCNC is a potential SOFC cathode material.

The double resonance Raman (DRR) peaks of Janus MoSSe monolayer are important fingerprints of material characteristics. However, the origin of DRR peaks is still poorly understood and needs urgent clarification. Based on density functional theory, high?order quantum perturbation theory and group theory analysis, the DRR spectra of Janus MoSSe monolayer were studied theoretically and systematically. It is found that the inverse lattice wave vector of the electro?optical resonance coupling process of Janus MoSSe monolayer depends on the laser energy, and any wave vector may appear in the first Brillouin zone. Based on group theory analysis, the symmetry conditions for the generation of DRR activity were deduced, and the fundamental reason for the occurrence of a large number of DRR peaks in the Janus structural system was elucidated. This study provides theoretical guidance for understanding the DRR processes occurring in two?dimensional Janus structural system, and provides a rational theoretical means for clarifying the origin of the DRR peaks.

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.

As an electrochemical inert cation, Mg²⁺ has an ionic radius (0.072 nm) similar to that of Li⁺ (0.076 nm), which is widely used to replace Li⁺ in Li?rich layered oxides (LLOs) materials. However, the influence of Mg²⁺ on the crystal structure of LLOs materials is still controversial. In this work, the Mg?doped Li?rich cathode materials Li_1.2-x Mg _x Mn_0.54Ni_0.13Co_0.13O₂ were synthesized by a sol?gel and high?temperature calcination method. The crystal structure, and valence state of elements in synthesized materials were systematically studied via X?ray diffraction, and X?ray photoelectron spectroscopy. These results indicated that Mg²⁺ doping can increase the cell parameters of LLOs materials. At the same time, compared with Li_1.2Mn_0.54Ni_0.13Co_0.13O₂, Mg?doping can effectively improve the electrochemical performance of LLOs materials. After optimization, the Mg?0.03 sample exhibits anomalous electrochemical performance, that is, the initial discharge?specific capacity is 291.9 mA?h/g and the initial coulomb efficiency is 78.40%.

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 wide application of clean energy, improving the transportation efficiency of gas pipeline has become a hot issue, among which, it is very important to reduce the friction resistance in the pipeline transportation process. In order to explore the application effect of triangular riblet in the drag reduction of gas pipeline, ANSYS?FLUENT software was used to numerically simulate the turbulent flow in smooth pipeline and riblet pipeline. The results show that: in the near wall area, the velocity profile of ribbed pipe and smooth pipe has a big difference, and the difference is small in the mainstream area. The drag reduction effect of riblet structure is mainly based on the near?wall surface. The riblet structure pushes the vortex away from the wall surface, filling the rib bottom with low?speed fluid, reducing momentum exchange near the wall surface and friction resistance. Compared with the smooth wall surface, the riblet structure with the size of s＝h＝0.516 5 mm has a drag reduction effect of 4.38%.

By constructing a skeleton model of MCM?41 loaded with various functional groups, the adsorption and diffusion properties of water molecules in McM?41 pores with different hydrophilic and hydrophobic properties were calculated by GCMC and MD simulations. The results show that the water adsorption isotherms of MCM?41 materials are mainly Ⅱ type. Hydrophilic functional groups loaded on MCM?41 pore surface can form hydrogen bonds with water molecules, so the interaction force on water molecules is about 114.27% higher than that of hydrophobic functional groups. The diffusion capacity of water molecules in the hole of MCM?41 is positively correlated with the hydrophilicity of surface functional groups, and the diffusion coefficient of water molecules in the material with hydrophilic surface is about 58.82% higher than that of the hydrophobic surface. It was proved that MCM?41 material with hydrophilic surface can promote the adsorption and diffusion behavior of water molecules in pores in aqueous environment.

Chemical wax inhibitors are widely used in the field of waxy crude oil extraction and transportation, providing an important guarantee for the safe and efficient operation of the waxy crude oil extraction and transportation process. At present, many basic experimental studies and numerical simulation studies on chemical wax removal have been carried out to explore the types, mechanism of action and application scope of chemical wax inhibitors. Common chemical wax inhibitors mainly include fused?ring aromatic hydrocarbon type wax inhibitors, surfactant type wax inhibitors, high molecular polymer pour point depressant type wax inhibitors and new nano?particle wax inhibitors. They usually prevent the association and deposition of wax crystals by water film theory or wax crystal modification theory. Among them, fused?ring aromatic hydrocarbon wax inhibitors, surfactant wax inhibitors, and polymer pour point depressant wax inhibitors have disadvantages such as poor environmental friendliness, poor environmental adaptability or poor economy. The focus of future research should be to explore green, efficient and general?purpose chemical paraffin inhibitors, use nanoparticles to improve the performance of paraffin inhibitors, and continue to explore more environmentally friendly chemical paraffin inhibitors.

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.

The solidifying point of shale oil is high, and the wax content is high and the emulsification degree of shale oil is high. As a result, it is not easy to dehydrate shale oil emulations by using the traditional thermochemical method, which is difficult to meet the export standard. High frequency pulse dehydration technology is an effective method to dehydrate, but there are few studies on the optimization of treatment parameters of shale oil produced fluid. In this study, the effect of high frequency pulse dehydration technology on Dagang shale oil emulsion was studied, and the treatment parameters were optimized. The results show that high frequency pulse dehydration technology can achieve effective demulsification of shale oil produced liquid and significantly reduce the water content of shale oil. Through the comparison and selection of treatment parameters, it is found that the increase of electric field intensity and electric field frequency is conducive to improve the dehydration efficiency. Besides, there are electric field action time, operation temperature and demulsifier concentration parameters with the best dehydration efficiency. It is proposed that under the electric field strength of 200 kV/m, electric field frequency of 5 kHz, electric field action time of 60 min, operating temperature of 75 ℃, demulsifier mass fraction of 0.010%, the water content of shale oil after dehydration is 0.48%, and the comprehensive benefit is the best. The research results provide technical support for the optimization of shale oil produced fluid treatment parameters.

As the main weighting agent of oil?based drilling fluids, barite has many problems with high?density oil?based drilling fluids. In order to explore the applicability of micro?manganese mineral powder in oil?based drilling fluids. The particle size distribution and microscopic morphology of barite and micro?manganese ore powder were analyzed by laser particle size analyzer and scanning electron microscope. The differences in rheology, water loss and wall?building, lubricity, settlement stability, and reservoir protection performance between barytic petroleum?based drilling fluid system and micromanganese slag oil?based drilling fluid system were studied. The results show that under the condition of low density, the difference between the micromanganese ore powder system and the barite system is small; under high density conditions, the micro?manganese ore powder system has low viscosity and high cutting, the viscosity coefficient of the mud cake is less than 0.10, the sedimentation density difference is less than 0.03 g/cm³, and the permeability recovery rate after acid dissolution is higher than 95.00%. Its rheology, lubricity, sedimentation stability, and reservoir protection performance are better than the barite system, but compared with the barite system, the micro?manganese ore powder system has a large water loss and poor mud cake quality. It is recommended to compound the micro?manganese ore powder with a weight Spar to improve the water loss of the system. The research results fully reveal the difference in performance between the micro?manganese mineral powder oil?based drilling fluid system and the heavy crystal oil?based drilling fluid system, and provide support for the micro?manganese mineral powder to improve the performance of high?density oil?based drilling fluids, and also increase the weight of high?density oil?based drilling fluids. It also provides a new development direction for the application of ultra?high density oil?based drilling fluid weighting agents.

Sinopec Dalian Research Institute of Petroleum and Petrochemicals developed the "low temperature diesel absorption" VOCs treatment device for an aromatics and styrene tank farm. However, the waste gas volume sucked into the liquid ring compressor is always unstable. In this paper, a new automatic bleed gas volume control scheme of liquid ring compressor was adopted, the optimal control parameters were obtained by designing the bleed air control scheme for the compressor motor frequency and the opening of the return valve of the liquid ring compressor according to the pressure on the pipeline connected to the tank area. The results show that this technology can meet the requirements of energy saving and consumption reduction while ensuring that the exhaust gas is discharged up to the standard, and take into account the long?term stable operation of the equipment.

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.

Based on the differential lever principle, a multi?stage compliant magnifying hinge was designed, and a micro?positioning platform with three translational degrees of freedom was assembled in an orthogonal way, and the symmetrical closed?loop structure formed has the characteristics of shock resistance, no cumulative error and better isotropy. The material is 7075 aluminum, and the stacked piezoelectric ceramics were used as the driving device to provide input displacement. Combined with the path search method and the static matrix method, the static balance equation and geometric deformation equation of the mechanism were obtained; the sensitivity analysis of the structural parameters was carried out, and the parameters with higher sensitivity in the mechanism are optimized with the displacement amplification ratio as the goal; a finite element analysis was performed on the assembly. The results shows that the stroke can reach 391.42 μm and the magnification is 13.05, and the platform has a high displacement magnification ratio and good positioning accuracy.

Carbonate cementation is one of the key factors to search for oil and gas exploration Sweet spots in low porosity and low permeability or deep sandstone reservoirs. Summarizing the research results of scholars at home and abroad is of great significance for guiding the exploration of favorable zones and the potential of remaining oil. Firstly, the types and distribution characteristics of carbonate cements in oil?bearing basins in China were systematically summarized, and it is considered that their distribution is characterized by diverse basin types, large age spans, and sedimentary facies dominated by abundant delta facies. It is mainly composed of calcite and dolomite, and can be further subdivided into three types of iron?free, iron?bearing and iron?carbonate cements according to the content of iron ions. Then it is concluded that the source and flow of fluid in diagenesis play an important role in controlling the type, genetic mechanism and distribution of carbonate cement by analyzing and summarizing the formation stage, material source, ion migration and precipitation factors of carbonate cement. In the end, several viewpoints on the influence of carbonate cements on reservoir quality were summarized, and some suggestions on the evaluation of the influence of carbonate cements on reservoir quality and some difficult problems to be further studied were put forward.

In the process of oil well operation, wireless communication technology can solve the problems such as high bit error rate and poor real?time performance in the down?hole parameter transmission. How to choose the characteristic frequency of sound wave and explore the attenuation degree of sound wave in the oil string have become the research hotspots in recent years. In this paper, the attenuation characteristics of acoustic signals transmitted along metal tube walls were studied, a communication model was established, and the attenuation law of acoustic signals was quantified on this basis. Combined with Comsol waveform simulation software, the correctness of communication theory model and characteristic frequency selection was verified. The results show that this method can effectively transmit acoustic signals and provide an optimal frequency selection scheme for oil well remote wireless communication technology.

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%.