A waterborne polyacrylate colloid with hard core and soft shell structure was synthesized with methyl methacrylate (MMA), styrene (St), butyl acrylate (BA), methacrylic acid (MAA) as monomers, diacetone acrylamide (DAAM) as crosslinking monomer and adipic acid dihydrazide (ADH) as crosslinking agent. By adjusting the glass transition temperature (Tg), the emulsion can be self?forming film without adding film forming additive at room temperature. The influence of DAAM?ADH crosslinking system on the properties of latex films was investigated. DSC and TGA analysis showed that the Tg and thermal stability of crosslinked latex films are higher than those of uncrosslinked films. When the mass ratio of DAAM in core?shell is 1∶2, the comprehensive performance of latex films is better than that distributed in core or shell alone. With the increase of DAAM content, the water absorption decreased from 18.99% to 4.38%, and the Gel Fraction increased from 79.30% to 90.84%. When the molar ratio of ADH/DAAM is 1.25, the water absorption reaches the lowest and the Gel Fraction reaches the maximum.
This paper compared the variation trend of the output and consumption of diesel and the difference of the qualities of different sources diesel with the standard of Ⅵ diesel in China, and analyzed the composition, quality and problems of diesel pool in detail. It is considered that the most important problems in diesel quality upgrading process is how to reach the standard of diesel density and cetane number (including cetane index), rather than diesel sulfur content. Therefore, some countermeasures were put forward, such as identify the difference between cetane number and cetane index, optimizing crude oil processing, hydro?converting inferior diesel and adjusting the product structure of refinery.
Using corn straw as raw material of biochar and modified with chitosan and rare earth, chitosan?lanthanum chloride?biochar composites and chitosan?cerium chloride?biochar composites were prepared respectively. The structure and performance of CBC?La and CBC?Ce were analyzed by XRF, FT?IR and XRD. The adsorption properties of Cr(Ⅵ) in water under different adsorption conditions were investigated. The experimental results show that the Langmuir equation can simulate the isothermal adsorption behavior well, and the quasi?first?order kinetic equation has a higher fitting degree. The theoretical equilibrium adsorption capacity are 21.08 mg/g and 19.16 mg/g, which is close to the actual value. The desorption experiments show that CBC?La and CBC?Ce had the possibility of reuse. The adsorption mechanism mainly includes electrostatic adsorption, complexation and ion exchange. The experimental results show that the chitosan?rare earth?biochar composite material has a good application prospect in the removal of Cr(Ⅵ) from water.
The coking kerosene fraction was used as the raw material for the experiment. The linear α?olefins in the raw oil were enriched by complex extraction method, and the high viscosity poly α?olefin base oil (PAO) was synthesized by oligomerization. The effects of temperature, time and catalyst dosage on the properties of PAO were investigated. The kinematic viscosity, viscosity index and PAO yield rate at 100 ℃ were determined. Under the optimum process conditions of catalyst mass fraction of 6%, polymerization temperature of 25 °C, polymerization time of 8.0 h, addition polymerization temperature of 80 °C and addition polymerization time of 2.0 h, the reaction effect is the best: The kinematic viscosity of PAO at 100 ℃ is 43.54 mm2/s, the viscosit index is 163, the freezing point is -50 ℃, and the flash point is 291 ℃. The yield is 85.48%. Compared with the PAO40 standard, the obtained product is a high viscosity lube base oil.
Metal nanomaterials with high thermal conductivity are ideal promoters for enhanced gas hydrate formation, including metal?based nanoparticles, metal oxides, and metalloid oxides. In this paper, the effects of different kinds of metal nanomaterials on the formation of gas hydrates were reviewed, and the effects of parameters such as the induction time and gas consumption of enhanced hydrate formation were introduced from the three aspects of additive concentration, particle size and surface properties. The results show that the heat transfer effect of metal?based nanoparticles is better, and some metal oxides and metalloid oxides will exhibit an inhibitory effect; the appropriate addition concentration and particle size have an important impact on the formation of hydrates. In addition, the combination of metal nanomaterials and chemical reagents can significantly improve the dispersion stability of nanoparticles, thereby promoting the efficient generation of hydrates.
In this paper, a kind of composite phase change material (capric?lauric acid/expanded vermiculite) using expanded vermiculite as the matrix and capric?lauric acid binary eutectic as the adsorbent was fabricated by vacuum impregnation technology. The chemical compatibility, morphology, stability，thermal?physical properties and reliability of the prepared composite capric?lauric acid/expanded vermiculite were investigated by fourier transform infrared spectrum (FT?IR), scanning electronic microscope (SEM), thermal gravimetric analyzer (TGA), differential scanning calorimeter (DSC) and thermal cycling test. The melting and solidification phase transition temperatures of capric?lauric acid/expanded vermiculite are 18.42 ℃ and 17.51 ℃, respectively. The latent heat of melting and solidification phase transition are 66.9 J/g and 62.9 J/g, respectively. Besides, the encapsulation amount of capric?lauric acid in expanded vermiculite can reach 52.97%, and it has good thermal stability between working temperature. Moreover, the capric?lauric acid/expanded vermiculite was used to substitute for a certain proportion of fine sand to prepare thermal storage mortar, the mechanical and thermal performance of capric?lauric acid/expanded vermiculite?based mortar was evaluated. The test result shows that prepared capric?lauric acid/expanded vermiculite?based thermal storage mortar is a potential material for building heat regulation and energy saving.
The types of volcanic rock reservoir space, reservoir physical properties and the main controlling factors were systematically studied by the method of reservoir physical property experiment, core casting thin section observation and X?ray diffraction test. The results show that the Yingcheng formation volcanic rocks in the Dehui fault depression have strong alteration, and the reservoir space is dominated by dissolution pores and dissolution fractures. The average porosity of tuff and dacite are 12.40% and 7.47%, respectively, and the permeability is less than 1.000 mD, belonging to type Ⅲ reservoirs. Gas?bearing formations can be further identified based on acoustic and resistivity logging methods. Lithology and lithofacies are the main controlling factors for the development of reservoirs, and lithofacies models of extrusive facies, extrusive facies and explosive facies were established in combination with the characteristics of seismic reflections. It provides an important theoretical basis for clarifying the mechanism of volcanic rock formation and the distribution of reservoirs in the study area.
To investigate the structure?function relationship of novel extended surfactants and the mechanisms of reducing interfacial tensions (IFTs) at oil?water interface, the interfacial tension values of 13?P series 13?P（I?C13（PO） x S,x=5,10,15,20）with different concentrations of NaCl and n?hexane to n?tetradecane at fixed concentration were measured by rotary drop interfacial tension meter. The result indicates that at higher numbers of PO（x=15,20), the nmin values become higher with increasing concentration of NaCl. At lower numbers of PO（x=5,10), the nmin values become lower with increasing concentration of NaCl. It reflects two mechanisms on reducing IFTs: Hydrophilic lipophilic equilibrium effect and hydrophilic hydrophobic group in size matching effect, both of which work together, and the size matching plays a crucial role at lower numbers of PO and HLB dominates at higher numbers of PO.
At present, the thermal recovery method is widely used in heavy oil recovery engineering, in which the high temperature and pressure wet saturated steam is injected into the oil well from the steam injection pipeline, and the heat carried by it is exchanged with low temperature heavy oil, so as to improve the fluidity and permeability of heavy oil and realize recovery. Wet saturated steam dryness is an important parameter affecting thermal recovery effino recognized measurement method existent method. There is no recognized measurement method. At present, the commonly used method is manual measurement, but the measurement results of this method have serious hysteresis. In order to achieve the purpose of real?time monitoring of dryness, a new measuring method, matrix conductance method, under the condition of 10 MPa and 310 °C, a 26×26 wire mesh model was established to measure the dryness of wet saturated steam in a steam injection pipeline with an outer diameter of 76 mm and an inner diameter of 54 mm. The measurement principle of the matrix conductance method is introduced and the dryness algorithm model is established. The electric field simulation was carried out in Ansys Electronics software, the electric field between the layers was analyzed, and the results show that the suitable interlayer spacing is 2 mm. In order to improve the accuracy, the linear interpolation method is used to process the edge, and the actual measurement error is predicted; the overall error after primary linear interpolation is within 2.50%; after quadratic linear interpolation, the overall error is less than 1.10%.
Nickel?based superalloys, as typical difficult?to?machine materials, are widely used in aerospace engines, chemicals, ships, and other fields. To meet the special working conditions requirements of the aero?engines, and further improve the surface machining quality and processing efficiency, relevant researchers have carried out many theoretical studies and process explorations. The development of nickel?based single crystal superalloys and polycrystalline superalloys, and their material properties were firstly reviewed. Then the main research results of domestic and overseas scholars on the grinding removal mechanism, grinding surface integrity, and process characteristics of nickel?based superalloys were summarized, and their development trends are prospected.
The modeling method of the machine tool spindle system is mostly beam and pipe element modeling. The system joint surface has two parts: The spindle and the tool holder, and the tool holder and the tool. These joint surfaces are mostly simulated by rigid connection or custom stiffness matrix. The system can also be modeled in the form of solid elements, while establishing contact pairs at the contact locations. In this paper, beam elements and solid elements were used to model the spindle system of a vertical machining center. Through the calculation results, the effects on modeling in different element types on the natural frequency of the system and the frequency response function of the tool nose point were compared and analyzed. The results show that the natural frequency value of solid element modeling is larger than that of beam element modeling, and the mode shapes are more abundant. With the increase of the excitation frequency, the amplitude?frequency response curve in the solid element modeling mode oscillates more violently, indicating that more excitation frequency values can be captured in this mode. The research results can provide theoretical reference for the dynamic characteristics of the spindle system for scientific research.
Carbon capture, transport and storage (CCS) plays an important role in the process of carbon neutralization. The flow and heat transfer process of supercritical CO2 and supercritical CO2 mixture in a vertical circular tube was studied with supercritical CO2, supercritical CO2+CH4 mixture (CH4 mole fraction is 1%, 3%, 5%) and supercritical CO2+N2 mixture (N2 mole fraction is 1%, 3%, 5%) as working fluids at a mass flow rate of 300～600 kg/(m2?s), heat flow density of 80～100 kW/m2, and inlet pressure of 8～10 MPa. The results show that with the decrease of CH4 and N2 mole fraction in the working medium, the peak value of heat transfer coefficient of the working medium increases gradually, and its corresponding temperature increases gradually; the heat transfer coefficient of the working fluid increases with the increase of the mass flow rate, and the greater the mass flow rate, the greater the change range of the heat transfer coefficient; with the increase of inlet pressure, the peak value of heat transfer coefficient of working fluid decreases, and its corresponding temperature increases gradually. Turbulent kinetic energy, buoyancy and specific heat capacity at constant pressure are closely related to the heat transfer enhancement of supercritical CO2 and its mixture.
In the research on the thermal efficiency of atmospheric tube heating furnaces, it is necessary to conduct effective online measurement of thermal efficiency and select relatively reliable advanced control methods. On the basis of the research on the combustion mechanism of the heating furnace, the online measurement method based on the principle and data processing is used to process the thermal efficiency, and the "dynamic matrix control" is introduced in the process of optimizing the control of the heating furnace efficiency, which is compared with the traditional control method. The introduction of dynamic matrix control makes the system have a better control effect. At the same time, the "particle swarm algorithm" was selected to optimize the parameters of dynamic matrix control. In the optimization process of dynamic matrix parameters, the particle swarm algorithm relatively shortens the optimization time and improves the control quality, so as to achieve a more satisfactory control effect. Finally, compare with internal model control, it shows that dynamic matrix control can achieve relatively better control effect.
Aiming at the problem of insufficient representation of interactive semantic information in the double human interaction behavior recognition method based on graph convolutional neural networks，a new double human interactive spatial?temporal graph convolution network (DHI?STGCN) was proposed for behavior recognition. The network contains spatial sub?network modules and temporal sub?network modules. Based on the 3D skeleton data obtained from the interactive action video, a spatial action graph of double human interactive action was generated for the representation of spatial information. In the graph, the connecting edges between double human were given different weights according to the joint point position information. The connection of context time information was added in the constructed adjacency matrix, and the joint points in the graph were connected with their nodes within a certain time range in time information processing. The generated spatial?temporal graph data was sent to the spatial graph convolution network module, and the temporal graph convolution network module was combined to enhance the continuity of inter frame motion features for modeling in time. The model fully considers the close relationship of double human interaction. The comparative experimental results on NTU?RGB+D dataset show that the algorithm has strong robustness and obtains better interaction recognition effect than the existing models.
The vibration signal during the operation of high voltage circuit breaker can reflect the mechanical state of circuit breaker. Aiming at the shortcomings of feature extraction and fault diagnosis accuracy of shallow vibration signal analysis model, a fault diagnosis method of high voltage circuit breaker based on convolutional neural network optimized by genetic algorithm was proposed. Using the global optimization ability of genetic algorithm, the optimal initial network structure parameters and the number of neurons in the whole connection layer were obtained through the selection, crossover and mutation of genetic algorithm to optimize the convolutional neural network, and the optimized convolutional neural network is applied to the fault diagnosis of high voltage circuit breaker. The results show that the diagnosis performance of the proposed network model is better than that of convolution neural network, dynamic support vector machine and multilayer perceptron.
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