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.

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.

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.

The hydrocracking unit is a Class A fire hazard device, which can be susceptible to fire and explosion accidents due to equipment failure. Therefore, it is essential to identify and quantitatively analyze the risk factors. In this paper, qualitative HAZOP, steady-state simulation, dynamic simulation and FTA are combined. Taking process flow of the absorbing-stabilizing system of an actual hydrocracking unit in a refining company as an example, and the quantitative risk analysis is carried out for the deviation of "high column pressure" of the absorption and desorption column and "high column temperature" of the naphtha stabilisation column. With the help of Aspen Plus software, the steady-state and dynamic simulation under dangerous conditions is carried out, and the probability of the consequences of the dangerous accident is calculated by FTA method. The results show that this method can help experts understand the propagation process of the accident, master the safety response time of the personnel, which is conducive to the prevention and timely treatment of accidents, and effectively improve the intrinsic safety level of the hydrocracking units.

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.

ZnO has a strong UV absorption capacity, but also has a high photocatalytic performance, which limits its application in the field of UV shielding. In order to explore the possibility of ZnO's application in the field of ultraviolet shielding, this article uses VASP to construct a ZnO/CeO₂ heterojunction and performs electronic and optical simulation calculations on it. Then lignin is used to combine with the synthesized ZnO/CeO₂ heterojunction to prepare lignin-modified nano-ZnO/CeO₂ heterojunction. Through the FT-IR, XRD, SEM, UV-Vis-DRS means the characterization of samples. The UV shielding properties of the synthesized samples were investigated with methylene blue as the protection object. The results show that the light absorption performance of the samples at 280～420 nm is better than that of ZnO/CeO₂ samples. The retention rate of methylene blue for 70 min under UV irradiation was 77.92%, indicating that the synthesized sample was a UV shielding material with high UV shielding properties and low photocatalytic activity.

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.

A model of a micro-texture tool featuring various textures such as micro-pits, parallel grooves, vertical grooves, and oblique grooves was developed. The impact of these micro-texture tools on the turning process of titanium alloy was investigated using the finite element analysis software ABAQUS. Through an examination of cutting force, friction coefficient, cutting temperature, and surface residual stress for micro-texture tools with distinct morphologies, the optimal micro-texture morphology was determined. The findings reveal that micro-texture tools can effectively reduce the cutting force, friction coefficient, and cutting temperature while transforming surface residual stress from tensile to compressive on the workpiece. Furthermore, with increasing cutting speed, cutting force and cutting temperature rises, friction coefficient decrease, and the residual stress on the workpiece surface shifts from compressive to tensile stress, exhibiting an ascending trend.

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.

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.

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.

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.

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.

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.

Protected amino acid compounds are often widely used as intermediates of drug molecules and functional material intermediates. The high efficiency of Boc-protected amino acid esters provides an important prerequisite for their subsequent conversion in the entire process. Boc-tert-butyl phenylalanine was selected as the raw material, and the process of selectively removing the Boc protecting group while retaining the protecting group of tert-butyl ester to generate tert-butyl phenylalanine hydrochloride was studied. Under room temperature or low temperature conditions, the yield of about 82% can be achieved by deprotection under acidic conditions, and the reaction conditions are simple and mild, and the cost of process equipment is low, which realizes simple operation, economical benefits and environmental protection.

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.

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.

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.

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．

In some areas of Xinjiang, the dip angle of coal seams can reach 50 °. Unlike horizontal coal seams, fluids in high dip coal seams are severely affected by gravity, and the pressure propagation law of coalbed methane wells has special characteristics. The optimal drainage and extraction well position needs to be optimized. This article considers the gravity effect of formation water and establishes a pressure propagation model for single-phase drainage in steep coal seam, and verifies the correctness of the model.Then, the water production of fractured wells in the inclined reservoir is calculated under stable seepage conditions, and the optimal drainage well position is optimized. Finally, numerical simulation methods are used to study the pressure propagation laws of single wells and well groups in heterogeneous bounded inclined reservoirs. The results show that in a high dip coal seam with an inclination angle of 45 °, the position where the distance ratio between the drainage well and the upper and lower boundaries is 3 : 1 is the optimal drainage well position; under the constant pressure drainage mode, there is not much difference in the pressure drop amplitude between the downward and upward tilt directions. In the constant speed depressurization and extraction mode, the pressure drop amplitude in the upward tilt direction is much greater than that in the downward tilt direction.

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.

Glass fiber (GF) reinforced nylon 6 (PA6) composites were prepared with a twin-screw extruder. The effects of GF mass fraction on the mechanical properties, thermal properties, density, water absorption and processability of PA6/GF composites were systematically investigated. The results show that the impact strength, tensile strength, flexural strength, flexural modulus, density and thermal deformation temperature of the composites increased with the increase of glass fiber content, while the water absorption and melt flow rate decreased with the increase of glass fiber mass fraction. The morphology showed that the GF was effectively wrapped and dispersed in the PA6 matrix when the GF mass fraction was increased up to 30%.

At present,most oil fields in China have entered the high water cut period,and the flow characteristics of produced fluid have changed, so it is possible to reduce the temperature of gathering and transportation.However,there are relatively few studies on the influence of pipeline materials on low-temperature gathering and transmission characteristics. Therefore, the characteristics of low-temperature gathering and transportation of high water content crude oil in steel pipe and fiberglass pipe are studied.The results show that the wellhead back pressure rises and the oil temperature at the end of pipeline drops slowly after the water content of the pipeline is reduced. The wellhead back pressure rises differently under different water content.When the water content is the same, the temperature of fiberglass pipe is lower than that of steel pipe, and the minimum water content of fiberglass pipe for low-temperature gathering and transportation is lower than that of steel pipe under the same condition.Based on the experimental data of viscosity wall temperature,the calculation models of different pipe materials are obtained,and the calculation results are accurate, which has a guiding significance for the feasibility judgment and safe operation management of the oil field in the high water cut period.

A novel organic-inorganic hybrid material [Ag(DPPE)₂]₂[Mo₄O₁₀(CH₃O)₆]·2CH₃OH (1) has been prepared by using [Mo₄O₁₀(CH₃O)₆]^2- in polyoxometalate (POMs) as inorganic building block, 1,2-bis(diphenylphosphine)ethane (DPPE) as an organic ligand and silver nitrate as a silver source, through the means of a combination of solvothermal and conventional synthesis and via the self-assembly process. X-ray single crystal diffraction analysis shows that compound 1 is formed by electrostatic interaction with polyanion [Mo₄O₁₀(CH₃O)₆]^2- and [Ag(DPPE)₂]⁺ cationic units. In addition, the structure of the compound was analyzed by X-ray powder diffraction and fourier transform infrared spectroscopy. The stability was determined by thermogravimetric analysis, the band gap was determined by solid UV-visible diffuse reflection test, and the fluorescence spectra in methanol solution were measured. It was found that compound 1 showed good photocurrent response.

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.

To investigate the influence of ordered micro texture design on the dynamic pressure effect of dry gas seal T‐groove, based on the principle of gas film lubrication, finite difference method was used to study the effects of ordered micro texture variables such as micro texture arrangement spacing, micro texture length, T‐shaped groove base length and width, and micro texture gradient inclination angle on sealing parameters. The design variables of four types of micro textures were compared. The results show that the micro texture of the T‐shaped groove can change the dynamic pressure effect of the groove itself, just like the structural parameters of the T‐shaped groove, but it does not change the dynamic law of the dry gas seal groove itself. The influence of microtexture variables on the opening force of T-shaped grooves in dry gas seals: microtexture gradient inclination angle>microtexture arrangement spacing>microtexture length and width>T-shaped groove base length and width amplification; The impact on leakage rate: microtexture length and width>microtexture arrangement spacing>T-shaped groove base length and width amplification>microtexture gradient inclination angle. The research results have certain reference value for the optimization and design of bi‐directional rotating end face gas film seals.

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.

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%.

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 combination of remote sensing image information extraction and artificial intelligence algorithms is an important technical tool for land use status survey, monitoring and management in land resources and environmental departments.Aiming at the problems of insufficient spatial information localization and inaccurate multi-scale target feature segmentation generated by U-net in remote sensing image extraction, a CA-Res2-Unet model incorporating an attention module into the head of Res2Net to replace the coding part of U-net is proposed, which aims to enhance the spatial localization and multi-scale feature information segmentation capability of U-net.Experiments were carried out on mainstream networks and improved models through the WHDLD public data set and the self-made data set of Shenfu New District. The results show that compared with the basic model, OA, M_IoU and F1 indexes of the experiment on the WHDLD public data set and the self-made data set of Shenfu New District increased by 0.92%, 2.00%, 1.58% and 1.18%, 2.87%, 1.91%, respectively. The visual effect and quantitative indexes of the proposed method are superior to other mainstream semantic segmentation networks, which can provide scientific basis for the investigation of the status quo of regional land use and the decision-making of relevant departments.

Infrared thermal imaging technology is widely used in the study of precursor characteristics and early warning methods of rock failure. However, infrared radiation precursory features have many forms, so it has certain influence on the accurate early warning of rock instability. The failure and instability of rock are closely related to the evolution of strain energy, and the infrared radiation information of rock is related to the dissipation and release of strain energy. If the strain energy is combined with infrared radiation information, the rock failure and instability can be monitored and warned accurately. Based on this, in this paper, the release time of elastic energy is determined by the cusp mutation theory based on the energy evolution characteristics, which is combined with the infrared radiation anomaly information to determine the precursor of rock failure and instability. The results show that with the sudden drop of the elastic energy curve, the infrared radiation synchronization appears abrupt change. The elastic energy release time of sandstone predicted by constructing the sharp point mutation model can be divided into two situations: leading and lagging the first mutation time of infrared radiation. Taking the elastic energy release time as the standard, the infrared radiation mutation near the sandstone can be regarded as the precursor of sandstone failure. The results can provide a new idea for mine disaster monitoring and early warning.

The defect detection of non-woven fabrics can help enterprises improve production efficiency and save costs. Due to the local characteristics of the convolution kernel, the object detection algorithms based on CNN lack the global modeling of the image, and the detection effect is not ideal for defect detection with a large range of scale changes. Therefore, a non-woven fabric defect detection method is proposed based on the combination of Swin Transformer and YOLOv5, which encodes and decodes features through its powerful self-attention. The network can obtain a larger receptive field and fully relate to the context. The layered construction based on the feature pyramid of Swin coincides with the design of the neck of YOLOv5. It can help the network predict the target on the multi-scale feature map. On this basis, CBAM attention mechanism is introduced to help the network focus on important information. Through Mosaic and MixUp data augmentation, the data distribution is enriched and the robustness is increased. Finally, the anchor size of the prediction target frame is fine-tuned to make the regression prediction more accurate. The effectiveness of the proposed method is verified on the self-made data set, and the detection performance of non-woven fabrics is improved.

At present,there are few studies on the influence of medium and low water saturation on the capacity of free gas storage.Therefore, this study simulates the multi?round gas injection?soaking?production process through laboratory experiments; The laboratory experiment was carried out to simulate the process of multi?round gas injection?well soaking?production. Combined with the mathematical model and numerical simulation results, the research shows that the reservoir capacity increases with the increase of injection?production rounds, but the increase after single?round injection?production decreases rapidly.When the initial water saturation is higher than 50%, the increase of water saturation is beneficial to the reconstruction of gas storage, but the increase of injection?production capacity and storage capacity is relatively slow in the early stage of reservoir construction. When the initial water saturation is increased from 50% to 85%, the gas saturation is reduced by about 9.27% after 6 injection?production cycles. When the injection?production cycles are increased to 20,30,50 cycles, the free gas storage capacity is increased by about 0.51%,3.33%,6.61%, respectively. The research results are expected to provide reference for the evaluation of injection?production capacity and storage capacity of reservoir?type gas storage.

In recent years, with the continuous increase of foreign crude oil imports and the decline of domestic oilfield production, different oil products may need to be transported together by the same oil pipeline during the transportation process.The fourth oil pipeline of Qingtie is taken as an example. Combined with the actual parameters, the pipe wall is discretized by using the finite element analysis method of ANSYS and the hexahedral structural grid. The thermal structure coupling problem of the buried pipeline is solved, and the corresponding thermal stresses of the straight pipe section and the bent pipe section at different temperatures are calculated respectively. Based on the theory of fracture mechanics,the number of annual limit cycles under different service life is calculated, and the influence of temperature alternation on pipeline fatigue life is analyzed, which provides a theoretical basis for the safe transportation of cold and hot crude oil pipelines.

The robustness of the particle swarm system is great, which is very helpful for solving ill?conditioned problems such as image reconstruction. However, the large number of pixels in the reconstructed image leads to a large dimension of particle and it is difficult for the particle to achieve the optimal solution in the optimization process. In order to solve this problem, a constraint is added to the particle position, imaging by Tikhonov regularization algorithm is used as the reference of particle position. The search for particles is constrained to the range of Tikhonov regularization algorithm reconstructs the image. Using the penalty function to solve the constraint problem to improve the particle search speed. Linearly decreasing weights as inertial weights for particle swarms optimization to realize the adaptive dynamic adjustment of the inertia weight and improve the flexibility of the algorithm; the chaotic operator is added to the position search process of the particle swarm optimization, when the particle falls into the local optimum, the chaotic variable will fluctuate within a certain range, reducing the missed rate of the optimal solution. The simulation results show that The improved particle swarm algorithm is more accurate and efficient than the traditional LBP algorithm and Tikhonov regularization algorithm.

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 Cu plate was fabricated by a novel grinding tool via multiple rotational grinding under deep cooling condition. The surface morphology, microstructures and properties of the grinding zone were analyzed via super depth of field microscope, optical microscope, friction and wear test, respectively. The results show that well surface formation and ultrafine grains were obtained after multiple rotational grinding under deep cooling condition. Combined with the temperature distribution simulation, the main grain refinement mechanism of 50 r/min is the breaking and split of the grain. The grain refinement mechanism at 500 r/min is dynamic recrystallization and forced cooling to inhibit the growth of recrystallized grains. Microhardness tests and wear tests showed that the ultrafine?grained zone prepared by multiple rotational grinding under deep cooling condition could improve the wear resistance of the materials.

Copper nickel alloys have excellent corrosion resistance and mechanical properties, therefore it is widely used in marine engineering. However, due to its complex service environment, copper nickel alloys are prone to corrosion and leakage, resulting in irreversible losses. A corrosion?resistant conversion film was prepared on the surface of copper nickel alloy to improve its corrosion resistance performance; Electrochemical impedance, Tafel polarization curve, scanning electron microscopy, and energy spectrum analysis were performed, and the surface covered corrosion products of the conversion film were observed by X?ray photoelectron spectroscopy (XPS). The results showed that when the B10 copper nickel alloy sample was immersed in a solution containing molybdate for 120 minutes, the solution transfer resistance (R_ct) and membrane resistance (R_p) reached their peak values, and the corrosion inhibition rate was as high as 92.5%; the conversion film contains copper and nickel oxides as well as hydroxides, while molybdenum exists in the form of +4 and +6 valence oxides.

A base?catalyzed 1,6?conjugate addition of p?QMs for the preparation of diaryl methyl ethers (thioether) has been developed with 37% to 95% yields, which realized the solvolysis reaction between p?QMs and alcohol (thiophenol) under the catalysis of 20% NaOH. The method features easy operation, mild condition and good functional tolerance. A gram scale experiment was examined in 80% yield, which provides possibility for potential application and transformation in later stage.

To study the influence of hydrogen mixing ratio on the leakage of natural gas pipelines, a mathematical model for the leakage and diffusion of directly buried high?pressure hydrogen mixed natural gas pipelines was established based on computational fluid dynamics theory and numerical simulation method.The leakage status, volume fraction distribution of hydrogen mixed gas,and the distribution of soil pressure and gas velocity around the pipeline were analyzed under different hydrogen mixing ratios.The results show that with the increase of hydrogen mixing ratio, the explosion radius of hydrogen mixed gas in the atmosphere will gradually decrease,and the range of high?pressure area around the pipeline will gradually decrease,and the gas flow rate at the leakage port will gradually increase.When the hydrogen mixing ratio is 30%,the explosion radius in the atmosphere is reduced by 43%,and the gas flow rate at the leakage port is increased by 68%.This provides a theoretical reference for the safety and emergency repair of hydrogen?doped natural gas pipelines and has important practical significance for promoting the large?scale application of hydrogen?doped natural gas.

Direct flame impingement heating technology is widely used in the field of steel heat treatment processes and is currently fueled by natural gas. Hydrogen, as a clean energy source and its high laminar flame propagation speed, combined with natural gas will improve the fuel combustion speed and reduce the emission of carbon oxides and nitrogen oxides. In this paper, a numerical model of direct flame impingement heating of steel plate was established using Fluent, and the heat transfer characteristics of direct flame impingement heating of steel strip were investigated under different hydrogen doping, Reynolds number, and factorless distance conditions. The results show that the temperature and heat flow density of the steel plate of the heated target decrease with the increase of hydrogen doping from 0 to 25% at a heating time of 10 s. The temperature of the steel plate stationary point decreases from 385.36 K to 374.31 K, and the heat flow density of the steel plate stationary point decreases from 154 828 W/m² to 137 926 W/m². With the increase of Reynolds number from 13 400 to 33 600, the steel plate stationary temperature increased from 347.04 K to 450.90 K, the pressure increased from 14.93 Pa to 136.53 Pa, but the uniformity of the temperature and pressure of the steel plate deteriorated gradually. The increase of the causeless distance from 25 to 45 made the temperature of the steel plate stationary point decreased from 442.42 K to 344.36 K, and the pressure was reduced from 106.00 Pa to 24.81 Pa and the distribution was more inhomogeneous.

The crude oil produced by oil wells contains sediment, scale and other particles, which are deposited together with the wax in the process of crude oil pipeline transportation. It leads to a decrease in pipeline throughput, and may cause pipeline blockage and affect the safety of transportation in severe cases.The yield stress test and microscopic characteristic experiments show that there is a critical scale containing ratio in wax deposits of the influence of calcium carbonate scale on the strength of wax deposits. And it is found that the wax deposits containing scale will increase the breaking force on the wax layer and the pigging efficiency of the pig through the indoor pigging experiment of polyethylene pipeline. Based on the data of pigging experiment, a prediction model of pigging efficiency was established by using the π theorem. The model was validated by indoor experiments and third?party literature experimental data.

Traditional mechanism models of greenhouses are difficult to reflect the real greenhouse environment due to nonlinear, multivariate, and strongly coupled characteristics. In this paper, extreme learning machine (ELM), back propagation (BP) neural network, and support vector machine (SVM) are used to predict and analyze the temperature, humidity, and light intensity of the greenhouse. The results show that the predicted values of ELM model are the most similar to the real?time parameters of greenhouse environment. In order to further improve the prediction accuracy of environmental parameters in the greenhouse, the improved sparrow search algorithm (ISSA) is used to optimize ELM model in this paper. The predicted environmental parameters are in good agreement with the measured data of a greenhouse in Tianjin, which confirms the feasibility of the proposed prediction model for the control of greenhouse environment.

The parameters of PID controller determine the stability and speed of tension control system, so it is important to study the parameter tuning optimization of classical PID controller in winding tension control. The PID tension controller based on the modified whale algorithm is designed by combining PID and modified whale optimization algorithm with winding tension control as an entry point. The improved whale algorithm (L?WOA) is combined with PID in order to improve its convergence speed and convergence accuracy when rectifying the PID parameters. A mathematical model and a dynamic torque balance equation are developed to analyze the effect of wire speed and web diameter on web tension. The parameters are optimized using the modified whale algorithm and various other algorithms, respectively, and the results show that the PID controller optimized by the improved whale algorithm proposed in this paper has the advantages of rapid response, more steady output, sturdy anti?interference ability and better robustness when the PID controller is controlled.

As a new type of clean, carbon?free, sustainable and efficient energy source, hydrogen has great potential in the future energy mix. Hydrogen purification by pressure swing adsorption is the main separation technology for hydrogen production with high purity, low energy consumption and high degree of automation. In this paper the progress in research and application of pressure swing adsorption hydrogen production in theoretical simulation, process control optimization and adsorbent materials were critically reviewed, and the future development of pressure swing adsorption hydrogen production technology was prospected.

In earthquakes and other natural disasters, there are often large and small debris on the road, which will affect the rapid passage of emergency vehicles. Installing lifting mechanism on the vehicle chassis is an effective way to solve this problem. However, the existing lifting mechanism lifting method is relatively single, occupies a large space, and is inconvenient to install underneath the vehicle. In addition, it also faces the problem that it can not be lifted flexibly with different working conditions. In order to solve these problems, this paper designs a metamorphic lifting mechanism based on the principle of metamorphic, which has the characteristics of variable topological configuration and variable degrees of freedom, and can complete the work task in different configurations according to different working conditions. For obstacles of different sizes, the mechanism can be elevated in one or two stages to realize rapid obstacle crossing. In this paper, after establishing the virtual prototype model of the metamorphic lifting mechanism, ADAMS software is used to carry out the configuration change dynamics simulation experiment, which investigates the dynamics of the vehicle in the process of configuration change and verifies the feasibility and stability of the mechanism.

The chemical storage tank area is a place with a large number of hazard sources, and the dynamic risk of the storage tank area cannot be quantified and characterized by traditional emergency management methods. Therefore, based on PPRR theory, a quantitative evaluation model of fire emergency management ability of chemical tank farm was established, and the weight of evaluation index was determined by interval analytic hierarchy process. The improved fuzzy comprehensive evaluation method was used to quantitatively evaluate the fire emergency management ability of chemical tank farm. This model is used to evaluate the fire emergency management ability of chemical tank farm of M Petrochemical Company, and the accuracy of this model is verified. The results show that the evaluation score of fire emergency management ability of chemical tank farm of M Petrochemical Company is 3.35, which is consistent with the qualitative evaluation result, and the accuracy of this model is verified. The model can solve the problem of uncertainty of the importance degree of the indicators, and the improved fuzzy comprehensive evaluation method can point out the deficiencies and degree of chemical tank farm, which can provide a new way to perfect and improve the fire emergency management ability of the chemical tank farm.

Through molecular dynamics simulation, the torsional deformation behavior of copper nanowires in different crystal orientations (Ⅰ: x[1 0 0] y[0 1 0] z[0 0 1], Ⅱ: x[1 0 1/8] y[0 1/8 0] z[－1/8 0 1], Ⅲ: x[1 0 1/4] y[0 1/4 0] z[－1/4 0 1]), different crystal orientation ratios (α₁=1/6, α₂=1/2, α₃=5/6), and different numbers of twin interfaces (0, 2, 4) were studied, as well as the relationship between the shear stress and torsion angle of copper nanowires during torsion. The results indicate that change the orientation type contributes to enhancing the torsional mechanical properties of copper nanowires. Reducing the ratio of internal diameter to external diameter also improves the torsional mechanical properties of copper nanowires. Furthermore, decreasing the number of twin interfaces can strengthen the torsional mechanical properties of copper nanowires. The torsion process of copper nanowires can be divided into three stages: elastic, plastic and deformation failure. The research results provide a basis for investigating the torsion of high?strength copper nanomaterials.

In order to improve the compatibility between rubber powder and matrix asphalt, the rubber powder was modified by microalgae bio?oil and compounded with SBS at 5% dosage to prepare modified asphalt. The changes of rubber powder before and after modification were analyzed by infrared spectroscopy and scanning electron microscopy; the dispersion of rubber in asphalt before and after modification was analyzed by viscosity, fluorescence and phase separation tests, and the mechanical properties and aging resistance of the modified asphalt were analyzed by dynamic shear rheology analysis and multiple stress creep recovery test. It was found that the incorporation of MB increased the proportion of light components in the mixing system, promoted the solubilization development of CR in asphalt, and improved the storage stability, viscoelasticity and rutting resistance of the modified asphalt.