The catalytic oxidation of molecular oxygen based on nitroxide radical organocatalysts is one of the hot topics in the field of catalysis in recent years. The structures and catalytic activity of the nitrogenous six membered heterocyclic ring obtained by the pyridine ring and the pyrazine ring substituted for the benzene ring of N-Hydroxyphthalimide (NHPI) were studied by theoretical methods. The effect of protonic acid HCl on the catalytic activity of this kind of catalyst was investigated. The results show that the catalytic activity of nitrogenous six membered heterocyclic ring catalyst is higher than that of NHPI, even some of the catalyst is comparable to that of N,N′dihydroxypyromellitimide (NDHPI); pyrazine pyridine ring chain is helpful to improve the catalytic activity of the catalyst; HCl hydrogen bond interaction with the aromatic ring of these catalysts can improve the catalytic activity of the catalyst. This study is helpful to deepen the understanding of the intrinsic activity of this kind of catalyst and also to provide theoretical guidance for the catalytic mechanism and catalytic oxidation experiment of this kind of catalyst.
Porphyrins, as one of the organic photosensitive units, play an important role in the construction of organic solar cells. They are responsible for the collecting, capturing and transmitting solar energy in nature with chemical stability and structurally adjustable. This review summarizes the basic structure and principle of PorphyrinPSC and PorphyrinDSSC, the basic idea of PushPull design of dye molecules and the progress of representative organic porphyrin solar cells in recent years. Based on the current photoelectric conversion rate of porphyrin solar cells, the desired molecular structures with further design and optimization, the industrialization of PorphyrinDSSC will be the next stage in the direction of efforts.
The adsorption characteristics of the alkaline nitride pyridine in simulated oil onto sixteen alkyl three methyl bromide(CTAB) modified SAPO-44 molecular sieve were studied. The effects of the amount of CTAB on the adsorption of basic nitrides on SAPO-44 zeolites were investigated. Moreover, the adsorption isotherms, kinetics and thermodynamics of the adsorption of alkaline nitrogen were studied. The results showed that when the amount of CTAB added was 0.06, the maximum equilibrium adsorption capacity reached 7.24 mg/g. The CTAB modified SAPO-44 molecular sieve has better adsorption efficiency when compared with the unmodified SAPO-44 molecular sieve. The adsorption isotherm of alkaline nitride on CTAB modified SAPO-44 molecular sieve is more in line with the Langmuir equation.The adsorption process accords with the pseudo second-order kinetic model, and the adsorption activation energy is 48.25 kJ/mol.
The numerical simulation study was performed on the sulfurous gas leakage diffusion. The effects of obstacles shape, slope size of obstacles and the distance between leakage hole and obstacles in the calculation region and different wind speeds on leakage diffusion process were analyzed. The hydrogen sulfide component and methane component safety area were simulated in the different conditions. The results showed that under the action of wind, the presence of obstacles changed the motion path of the gas leakage and led the leakage gas to store in front of its surface. The height of leakage gas diffusion was increased and its transmission in horizontal direction was prevented if the obstacle was no slope obstructions(buildings). The horizontal distance of leakage gas diffusion was increased if the obstacle was gradient obstacles(mountain), and the leakage gas started setting down in the protected area after it bypass obstacles when the wind speed was more than a certain speed, causing the safety area reduced.Reducing obstacles slope, light wind could not influence the diffusion of gas, the leakage of gas was surrounded by obstacles and diffused near the ground when the heavy wind came. Increasing obstacles slope, leakage gas diffusion regularity of slope was similar with no obstructions. The suggestion for emergency rescue and safety management of sulfurous gas leakage accident was provided.
Aiming at the problem in dynamic leakage of urban overhead gas pipeline,considering the impact of different pressure levels on leakage and diffusion, high pressure (2.0 MPa), sub high pressure (1.0 MPa) and medium pressure (0.4 MPa) three kinds of pressure grade pipe to simulate were selected.Firstly, the leakage rate of the critical flow and the sub critical flow were calculated by using the leakage rate calculation mode.Secondly, the leakage rule of different pressure pipelines was obtained.The Fluent software was used to simulate the unsteady state leakage, and the risk range of natural gas diffusion was obtained.The results showed that if the pressure in the tube was greater,the quality of residual gas in pipe and the time of leaking was higher and the risk range of natural gas was lager when the volume of pipe and the diameter of leak were fixed.With the continuous leakage of non steady state, the leakage rate was getting smaller and smaller, the risk of natural gas was also getting smaller and smaller.
The main index factors of the soil corrosion detection， for the section of pipeline in service in Qinghai Oilfield Huatugou, included resistivity, natural corrosion potential, redox potential, pH, moisture content, salt content, chloride ion content and soil corrosion rate. Combined with three theories, gray correlation, fuzzy evaluation, and improved AHP, the appropriate comprehensive evaluation model was established, the 15point set of measured data was used in Huatugou areas of this field to clarify its application of this method, and evaluation results reached by the comparison model with the original evaluation results were contrasted. The results of this evaluation model showed that the evaluation results was closer to reality than the original evaluation results.
With the development of oil and gas exploration and development in depth, the number of deep and ultra deep wells has gradually increased. Meanwhile, the hardness of the drilled formations has subsequently increased, the drilling speed is also greatly reduced. To solve this problem, a fire-suction impactor is developed. By providing the high frequency axial impact force to the drill bit, auxiliary rock breaking is achieved, thus greatly improving the rop. Otherwise, laboratory experiments show that the high frequency axial impact vibration of the fire-suction hydraulic impactor can provide some impact to the drill bit. On site experimental results show that the rate of mechanical drilling speed is increased by 133.0% after using the fire-suction hydraulic impactor. And the drilling time of fire-suction hydraulic impactor reaches 130 h, the downhole working time is 154 h, greatly improving the service life. The results of the study provide a theoretical basis for the reasonable application of the firesuction hydraulic impactor in the drilling process.
Carbon brush and slip ring were important parts of the generator excitation system. Due to some factors, the phenomenon of carbon brush getting high temperature or wearing affected the safe generator operation seriously. The force of pressure spring was got on carbon brush by experiment, pressure values of both 8 positive carbon brush and 8 negative carbon brush in two generators were analyzed, the pressure spring pressure of two generators carbon brush was compared, reasons of brush getting high temperature were got , and proposals for change were given.
Reducer as an important transmission, there is a very wide range of applications in many areas. A new design of reducer for oil pumping unit in oil field was introduced, and the modeling, assembly and simulation analysis of Pro/E software was used. The interference of gear running was obtained by position simulation, and the operation condition of internal gear of reducer was directly reflected. The drive ratio was verified through kinematics simulation| through dynamic simulation, the force of the mechanism was obtained, and the vibration condition of the mechanism was obtained by the force analysis. Direct application of Pro/E simulation could greatly improve the design efficiency.
With the rapid development of social networks, microblog has become a platform for the spread of information dissemination. In view of the characteristics of microblog information diffusion, mining the potential law of microblog forwarding process is of great significance for public opinion monitoring, hot topic tracking, product marketing and so on. In this paper, the Sina microblog is used as the data source, the user and microblog content are used as the characteristic source. The neural network prediction algorithm in machine learning is introduced to establish the prediction model to realize the forward prediction of microblog. The results show that, compard with the traditional prediction method, the microblog forwarding can make a higher accuracy prediction.
A new technique combining spatial domain and frequency domain is proposed, which can provide more watermarks in the condition of reducing the distortion of watermark image. The watermark is divided into two parts: the spatial domain and the frequency domain, and embedded into the spatial domain and the frequency domain according to the user's needs or the importance of the data respectively. Experimental results provide the comparisons when different sized watermarks are embedded into the grayscale image. The proposed combinational image watermarking possesses the following advantages. More watermark data can be embedded into the host image, so that the capacity is increased. The watermark is divided into two parts in spatial domain and frequency domain makes the degree of protection double. The splitting strategy can be designed to be more complex in order to make the embedded watermark unrecoverable. In addition, in order to enhance the robustness, a random permutation of the watermark is used to combat the attacks of signal processing such as image crops.
The constraints of automatic test paper are optimized, and the algorithm is improved according to the examination hierarchy of knowledge points . The knowledge points weight grading table is used when initializing the population , and the chromosomes in the initial population are selected according to the knowledge weight order so that the population can meet the requirement of the assessment level of the knowledge points from the initial time. In the design of the genetic operators maintains the stability of the population of knowledge point .The results show that the improved algorithm can improve the coverage rate of important knowledge points while guaranteeing the coverage of knowledge points.
The problem of robust L∞ reliable control for a class of time-delay systems with controller failures is investigated. Based on the idea of switching, the system with possible failure of the controller is transformed into a switching system with two subsystems, one of which is a stable subsystem without controller failure and the other is unstable in the event of controller failure subsystem. By using the multiple Lyapunov function theory and the average dwell-time method, the exponential stabilization and L∞performance of LMI are obtained, and the design scheme of the L∞reliable switching controller is obtained. Finally, the effectiveness of the scheme is verified by simulation.
The sources of inflation persistence were analyzed, including intrinsic inflation persistence, extrinsic inflation persistence, and expectationsbased inflation persistence. The multivariate structural time series model which measure inflation persistence based on the Kalman filter approach was used. The results showed that there was not only largely extrinsic inflation persistence, but also existed serious expectationsbased inflation persistence and extrinsic inflation persistence in China.
Based on the theory of GONE fraud, from greed, opportunities, needs and exposed four dimensions, the influence factors of financial fraud was analyzed, the 1992—2015 penalized agricultural listed companies were selected as research samples, and fraud identification model was build. It was found from the analysis that the dual role as the chairman and general manager intensified the efforts on fraud greed. Controlling shareholders in the nation's, the chance of financial fraud in companies was reduced. The higher financial needs were, the greater the risk of the enterprise fraud was in the rights issues. The performance of nonstandard audit opinion increased the probability of enterprise financial fraud exposure.
