Electroslag remelting(ESR) process is accompanied by a series of complex macroscopic transportation phenomena such as electromagnetism, flow, mass transfer and heat transfer, and a series of microscopic transportation phenomena such as the nucleation and growth of metal melt. Macro/micro-scopic transportation phenomena interact with each other and restrict each other, which determines the quality of the final remelted ingot. In the past few decades, many researchers have established the macroscopic mathematical models for macroscopic transmission of the electromagnetic field, flow field, temperature field and solute field, revealing the current density, magnetic induction intensity, Joule heat, electromagnetic force, temperature and solute element distribution, and two-phase flow of molten slag and melt in ESR system. Recently, the researchers have established a microscopic mathematical model for solidification microstructure of electroslag remelting ingots and revealed the evolution law of solidification microstructure, and liquid pool morphology and the influence of remelting process on solidification microstructure of ingot. However, in order to fully reveal the complex macro/microscopic transportation phenomena in ESR process, it is necessary to further study the charged ion migration behavior in the molten slag pool, the electrochemical reaction, the interdendritic solute diffusion and flow, the solidification and shrinkage of the ingot, and so on.
The porous SAPO-11 molecular sieves were prepared by dry-gel method under the condition of single or simultaneous addition of cetyltrimethylammonium bromide (CTAB) and polyethylene glycol (PEG), respectively, with pseudoboehmite, silica sol and phosphoric acid as aluminum source, silicon source and phosphorus source, dipropylamine and diisopropylamine as template. The synthesized SAPO-11 molecular sieves were characterized by XRD, nitrogen physical adsorption and desorption, SEM, NH3-TPD and Py-IR. The catalytic performance of the prepared Pt/SAPO-11 molecular sieve in n-dodecane isomerization reaction was investigated on a fixed bed. The results show that the addition of CTAB and PEG in the dry gel synthesis of SAPO-11 can promote the formation of mesoporous structure in the molecular sieve and change its morphology and acid strength. The selectivity and yield of the synthesized multistage pore SAPO-11 catalyst for n-dodecane hydroisomerization are significantly superior to those of the microporous SAPO-11 molecular sieve. The selectivity and yield of isoparaffin of Hier-Sapo-11-cp molecular sieve reach 71.2% and 62.1% respectively at 340 ℃.
3-Methoxythioxanthone was synthesized, and the structure is identified by1H NMR, 13C NMR, IR and HRMS spectra. The UV-Vis absorption spectra of 3-Methoxythioxanthone shows that it absorbs near the purple light (380 nm) in the visible range and is a visible light photosensitizer. 3-Methoxythioxanthone was applied to the Aza-Henry reaction of 2-phenyl-1,2,3,4-Tetrahydroisoquinoline and Nitromethane. Under the irradiation of purple LED, the photosensitizer with a molar fraction of 5% allowed the reaction to be isolated in a yield of 84% within 6 h. According to the experimental results, the mechanism of photocatalytic reaction of AzaHenry was proposed. The photosensitizer could transfer energy to produce singlet oxygen under the illumination, and singlet oxygen promoted the Aza-Henry reaction.
In recent years, under the requirements of national safety and environmental protection standards, the problem of oilfield sewage is usually solved by the boiler after treatment. On the one hand, it solves the problem of sewage discharge from oilfields, and on the other hand, saves water resources. However, due to various reasons, the sewage recycling boiler process has serious scales in sewage treatment systems and pipelines, boilers, oil pumps and other facilities. On the basis of the problem of scale formation in oilfield, this paper firstly introduces the development status of scale prediction model, including the combination of network neural principle, analytic hierarchy process, fuzzy analysis and other numerical analysis methods using MATLAB and other tools to fit the prediction model. In practical application, these prediction models have achieved higher precision values; then the latest research results of the methods of scale prevention and control in oilfields are introduced, including the addition of anti-scaling agent and anti-scaling agent. Second, the injected water itself is modified to solve the problem of incompatibility with the formation water, so as to achieve the purpose of preventing and controlling the scaling of oilfields.
Wax in waxy crude oil is one of the main reasons for the poor fluidity of crude oil. In order to solve the great difficulties brought by the fluidity of waxy crude oil to crude oil mining and gathering, it is necessary to carry out wax removal treatment on crude oil.Microbial paraffin removal technology is the use of microbial metabolism to directly degrade wax components in crude oil and degrade long chain hydrocarbons into medium and short chains, thus reducing the wax content in crude oil at all. By detecting the wax content in crude oil and wax crystal morphology before and after the treatment of compound bacteria, the effects of the compound bacteria on the degradation of wax components in crude oil and the morphology and size of wax crystals in crude oil are studied, it is concluded that the wax removal characteristics of the compound bacteria are analyzed macroscopically. Finally, the paraffin removal effect of the compound bacteria is verified from the microscopic point by detecting the particle size distribution of the oil sample after paraffin removal treatment.
Hydrogen as a clean fuel will play a critical role in the future energy landscape. The hydrogen production reaction of electrolytic water only produces hydrogen and oxygen, which has the advantages of low cost, high efficiency, environmental friendliness and good safety. The oxygen evolution reaction is a key ratecontrolled reaction step in hydrogen production from electrolytic water. A simple Pt loaded Li2Co2O4 synthesis method was introduced and its oxygen evolution performance was characterized. The effects of different Pt loading (mass fraction) on the electrocatalytic performance were compared, and the optimum Pt loading was obtained when the Pt loading was 5%. The structure of the material was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that a highly efficient catalyst capable of reducing the Pt consumption while maintaining the activity and durability of the catalyst is obtained.
Rare earth elements have a rich outer layer valence electron structure, which gives them many properties and has been widely used in many important fields. With the maturity of rare earth separation process, the price of rare earth continues to decline, which provides a guarantee for the large-scale application of rare earth elements in the field of supported solid phase catalysts. This paper mainly reviews the domestic and foreign applications and development status of heterogeneously supported catalysts modified by rare earth in the fields of petroleum processing, chemical engineering and photochemical. The modification process and application properties of rare earth elements in the field of heterogeneously supported catalysts are introduced in detail. The problems in the research of rare earth modified catalysts, the corresponding solutions and the development trend are considered and prospected.
In the development process of exploration in oil and gas fields, it is inevitable that foreign fluids can invade the oil formation and cause contamination to oil and gas reservoirs. In order to understand the potential factors that may cause oil and gas reservoir damage during the development of ultralow permeability reservoir in the Tang 80 well area of Gangu Yi oilfield, the reservoir sensitivity experiment of Yanchang 6 reservoir in the Tang 80 well area was carried out according to the reservoir characteristics of the Chang 6 reservoir. The results show that the reservoir in this area has certain acid sensitivity. This is mainly because the Chang 6 reservoir contains more acidsensitive mineral chlorite, which can produce harmful substances such as Fe3+ , Fe2+. Under certain conditions, the pore throat will be blocked by harmful substances, and the permeability of the oil reservoir is reduced. In addition, the Yanchang formation 6 reservoir in Tang 80 well field also contains weak velocity sensitivity, weak water sensitivity, weak alkali sensitivity and weak salt sensitivity. Meanwhile, the research area should be combined with the sensitivity of the oilfield reservoir during the development process, and take certain protective measures to mitigate the occurrence of acid sensitivity and other phenomena: Strictly control the flow rate and salinity of the external fluid; Use acidification, or develop a reasonable acidification process and limit the acidification scale.
In order to study the problem of distribution of mixed oil in T-shape pipeline of refined oil products. And the control equation of the sequential transport mixed oil is established by using multiphase flow model, 90# gasoline and 0# diesel are used as the alternate transportation objects. The process of downloading the mixed oil formed by gasoline and diesel under different conveying sequences through the branch pipe is numerically calculated, and the distribution of mixed oil quantity is obtained. The influence of the mixed oil in the main line on the mixed oil section under different conveying sequence is analyzed. The results show that the mixed oil in the main pipeline can be shortened by the appropriate amount of oil in the station provided along the line, which can significantly shorten the length of the mixed oil section and reduce the download pressure on the mixed oil section of the pipeline at the end station.
In the gathering pipeline, the velocity and pressure of the oil-water two-phase flow through the elbow will change, which will increase the corrosion degree of the elbow and lead to frequent accidents caused by corrosion of the elbow. Taking water as discrete phase, the flow state in pipeline is numerically simulated by the combination of RNG turbulence model and DPM model. The variation law of pipeline corrosion influence factor is obtained, and the simulation data is processed by origin software and analyzed by orthogonal test method. The results show that the different pipeline parameters have different effects on cavitation corrosion rate. Among them, the pipe diameter has the greatest influence, the mass flow rate of water droplet particles, the inlet velocity of the fluid, and the bending angle of the pipe are the second, and the bending diameter ratio has the least influence on the cavitation corrosion rate.The research results can provide the technical support for the design and operation management of the gathering pipeline.
The DEMATEL algorithm is an algorithm for analyzing the relationship between the influencing factors of complex systems. The algorithm has important application value for identifying the key factors of complex security system. First, on the basis of the DEMATEL algorithm, according to the knowledge of cognitive psychology and the status quo of the safety management of a gas station, the complex gas station safety system is divided into 4 subsystems, and further refined into 31 specific factors. Secondly, according to the DEMATEL algorithm, the MATLAB program is compiled to divide the cause factors and the result factors, and the influence degree, cause degree and center degree of each factor are calculated. Finally, the location of the key factors are displayed intuitively by drawing the cause results diagram. The results show that the information channel interruption, lack of recognition and information uncertainty, contingency plans and response defects are the key factors affecting the safety of gas stations. The longterm solution for gas station safety management is to control these 4 factors.
A heat exchanger produced by a company. The tube medium of the heat exchanger is temperature-controlled water, and the shell medium is low-pressure steam. The heat exchange equipment suddenly leaked in less than half a year, causing the equipment to stop. During the maintenance inspection, cracks were found at the tube head of the heat exchange tube, and the cracks were circumferential cracks, and some tubes even broke. Therefore,the chemical composition, hardness, mechanical properties and metallographic structure of the heat transfer tubes were tested and analyzed. The micro-morphology of the crack was observed and analyzed by SEM, and the product of the heat exchange tube fracture was analyzed by EDS spectrometer. The results show that the inclusion is part of the cause of the cracking of heat exchange tube, and the corrosive medium in the heat exchange tube is an important cause of the failure of heat exchange tube. The excessive internal stress in the heat exchange tube is the root cause of the failure of the heat exchange tubes.
Based on the bow baffle, the same working conditions are set. The FLUENT software is used to simulate the flow and heat transfer performance of the shell, fluid and heat transfer of the three baffle plates of curved, spherical and arched shapes. and the pressure drop and heat transfer coefficient of the shellandtube heat transfer with three types of plate are compared and analyzed. By comparing the heat transfer performance, pressure, temperature and velocity nephograms of the three plate heat transfer, the reasons for the difference in heat transfer performance are analyzed. The research results can provide reference for the design and heat transfer enhancement of the shell and tube heat transfer baffle, which has certain engineering practical significance.
Because of the rapid development of the convolutional neural network in recent years, the re-recognition of pedestrians has become another area of computer vision that is worthy of research after face recognition. The pedestrian re-recognition method involves verifying the similarity of two pedestrians or whether they are the same person and measuring the similarity of two features. And a pedestrian is a picture formed by multiple cameras, and its external conditions such as illumination, angle, and distance and it will increase the difficulty of verifying the similarities of two features. In this paper, a new method of pedestrian re-recognition based on combined Joint-Bayesian method and multi-camera shooting is proposed, which can effectively solve the problems caused by the change of shooting conditions of different cameras. Due to the good feature measurement ability of Joint-Bayesian, this paper studies a set of Joint-Bayesian matrices under different cameras, and combines with the global Joint Bayesian matrix to obtain a good recognition rate. On the Market-1501 and DukeMTMC-reID, the proposed method is used. The Rank-1 reached 88.09% and 80.07%, and the mAP reached 78.24% and 70.91%, which verified the effectiveness of the proposed method.
A color image encryption method is proposed. The method uses discrete fractional random transform (DFRNT) and Arnold transform (AT) to encrypt in the luminance hue saturation color space. A color image is converted from the standard red-green-blue (RGB) space to luminance hue saturation space . The luminance component is encrypted by a method DFRNT transform, which encrypts the pixel value and the pixel position simultaneously. The hue and saturation components are encrypted using an Arnold scrambling method that scrambling pixels. Compared with the traditional double-random-phase encoding, the DFRNT encryption method can save storage space of the encryption key. At the same time, it is as safe as the traditional dual random phase coding. The fractional order of the DFRNT, the random matrix and the iteration numbers of Arnold transform are used as the encryption keys of the algorithm. The performance of the cryptographic algorithm is analyzed against the variation in fractional order, the change of Arnold transform iteration number, known-plaintext attack, noise addition and occlusion of the encrypted image. The test results show the feasibility and effectiveness of the scheme.
Based on the Kuznets curve (EKC curve) model, the environment-income logarithmic model with cubic terms is constructed, and the four types of regional pollution indicators data including water pollution, air pollution and solid waste pollution in China from 2000 to 2014 are utilized. And the relevant data of environmental monitoring in Liaoning Province. The regression curve with the best fitting degree was obtained, and the data of the whole country and Liaoning Province in 2015 were verified. The relationship between environmental pollution indicators and economic growth (per capita GDP) in Liaoning Province and the whole country was analyzed and forecasted.The results show that, both the Liaoning Province and the whole country, with the increase in per capita GDP, the per capita wastewater discharge and smoke dust emissions increase, and the per capita chemical oxygen demand emissions and sulfur dioxide emissions decrease.
From the perspective of input and output, the DEA-Tobit method is used to improve the corporate social responsibility input and corporate performance layer by layer, and the maximum likelihood estimation of the optimal solution is verified according to the DEA censored data. The empirical analysis of corporate social responsibility performance of listed manufacturing companies in Shanghai and Shenzhen stock market shows that the overall investment in corporate social responsibility optimization has more obvious fluctuation characteristics than the amount of corporate social responsibility. Meanwhile, corporate philanthropic responsibility input has more obvious fluctuation than corporate ethical responsibility in the improvement of corporate performance.
