Editor in chief：朱立光
International standard number：ISSN 1008-1542
Unified domestic issue：CN 13-1225/TS
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2020, 41(4):289-295. DOI: 10.7535/hbkd.2020yx04001
Abstract:In order to solve the problem that the actual current cannot closely follow the given current or the predicted output voltage fluctuates too much due to the unreasonable selection of the weight coefficient when the model predictive control seeks the optimal control variable, a model predictive control method based on fuzzy control dynamically selecting weight coefficients was proposed. Fuzzy control was applied to the selection of the weight coefficient, and the optimal weight coefficients can be sent to the currently running model predictive control system online. Three groups of experiments were conducted for the simulation, comparison and analysis of different weight coefficients, and the reasonable interval of the weight coefficient was obtained. The simulation results show that the weight coefficient based on fuzzy control has good performance. When the load change is severe, the robustness of the motor is well, and the current can closely follow the given current; When the load change is gentle, the output voltage fluctuation will be reduced under the condition that the current can follow the given current. The improved control system improves the anti-disturbance ability, and the weight coefficient can be changed automatically according to the actual demand, which provides some reference for the control design of permanent magnet linear synchrous motor.
2020, 41(4):296-302. DOI: 10.7535/hbkd.2020yx04002
Abstract:Aiming at the problem that the Global Navigation Satellite System (GNSS) is confronted with great challenges in terms of continuity, integrity and usability due to the complex electromagnetic environment, an improved signal detecting algorithm of weak interference based on polarization-sensitive array was proposed. Through the joint-processing in space domain, frequency domain and polarization domain of the real-time data received from antenna elements and the descending processing of eigenvalues in each frequency bin, the weak signals in strong interference environment could be accurately separated and identified by the distribution curve of eigenvalues in the whole frequency domain. The results show that the power consumption and computational complexity were reduced greatly through the improved minimum description length (MDL) criterion based on multistage wiener filter, as the step of eigen-decomposition was omitted. Simulation results also demonstrate the efficiency and accuracy of the proposed method. The improved algorithm can be applied to different antenna arrays, keeps highly effective detecting probability even with amplitude and phase errors, and has high engineering practice value.
2020, 41(4):303-314. DOI: 10.7535/hbkd.2020yx04003
Abstract:The ripple component of the DC bus voltage will affect the power supply quality of the entire DC microgrid and the safety of equipment operation. Therefore, a new DC active power filter (DC-APF) control strategy was proposed to suppress the DC bus voltage ripple. The ripple detection method and suppression scheme were optimized based on the analysis of various work modes of DC-APF. A DC bus voltage ripple detection method based on wavelet transform Mallat algorithm was proposed. On the basis of traditional and fuzzy PI control, an improved fuzzy adaptive PI control was proposed to realize the tracking control method of compensation current. A DC microgrid system model with DC-APF was built in MATLAB/Simulink. The simulation results show that, compared with the traditional DC-APF control method, the new type DC-APF control strategy can achieve rapid detection of DC bus voltage ripple and has good ripple compensation effect. The proposed strategy can improve the detection performance and suppression effect of DC-APF on ripple, which provides a new method for ripple detection and suppression in DC microgrid.
2020, 41(4):315-326. DOI: 10.7535/hbkd.2020yx04004
Abstract:The types of questions answered by the visual question answering of images and texts are roughly divided into two types. The first type is the questions that can get the answers directly from the images, and the second type is the questions that need the help of external knowledge to obtain the answers. The current visual question answering method only has a high accuracy in one kind of questions, but the technology to answer the second kind of questions is not yet mature. In order to expand the types of questions that can be answered, a visual question answering method- K-VQA was designed with the help of knowledge graph. On the basis of deep learning VQA, the types of questions are distinguished by querying the knowledge graph, so that different types of questions can be answered with the most appropriate method. For the questions that need to be answered with external knowledge, the images and information in the questions are used to determine the entities and attributes required to answer the questions, and the triples in the knowledge graph are extracted to obtain the answers to the questions. The results show that different visual question answering techniques are suitable for different types of questions. The K-VQA method can answer both simple questions and reasoning questions with an accuracy of 5667%. Therefore, as a visual question answering method assisted by knowledge graph, K-VQA can answer more types of questions and obtain higher accuracy, which has important reference value for further study of VQA and VQA methods..
2020, 41(4):327-333. DOI: 10.7535/hbkd.2020yx04005
Abstract:In order to deeply study the characteristics of Kirchhoff equation, the existence result of the least energy sign-changing solutions to Kirchhoff equation with Hartree term and critical growth nonlinear term was discussed. The technical result of the space E compact embedding L6([WTHZ]R3)[WTBZ] was obtained by using the infimum of the energy functional on the sign-changing Nehari manifold convergences to zero. The results shows that the minimum point corresponding to the minimizing sequence obtained by the restricted variational method and quantitative deformation lemma is the nontrivial solutions for the problem. The research method in theoretical proof gets effective results and has a certain guiding significance for studying the existence of solutions of other Kirchhoff equations.
2020, 41(4):334-340. DOI: 10.7535/hbkd.2020yx04006
Abstract:Aiming at the problem that there are many kinds of tricyclic graphs and the complexity of path matrix is high, the path energy of two kinds of tricyclic graphs with or without pendant vertices was studied by means of matrix analysis, the existence theorem of root and scaling of inequality. Firstly, four kinds of path matrices of two kinds of tricyclic graphs with or without pendant vertices were given, then the real-symmetric matrix was partitioned by matrix analysis to obtain the corresponding characteristic polynomials. The number of positive and negative eigenvalues was determined by the existence theorem of the root and the Vieta theorem, and the range of values was estimated. Secondly, the path energy of two kinds of tricyclic graphs with or without pendant vertices was found out by scaling inequality. The results show that the number and range of negative eigenvalues of the two kinds of tricyclic graphs are different when there are pendant vertices or not, so the corresponding path energy of tricyclic graphs is also different. The obtained results have certain reference value for the study of the path energy of extreme value problem of the tricyclic graphs, and it is conducive to speculate the structural properties of related chemical molecules.
2020, 41(4):341-348. DOI: 10.7535/hbkd.2020yx04007
Abstract:In order to study the stability of cefuroxime axetil acetone solution, by using high-performance liquid chromatography, the single factor test was conducted to study the variation ofcefuroxime axetilcontent in the solution with time under different conditions such as the initial solution pH, temperature and oxidant species. The chemical reaction kinetics method was used to establish the degradation reaction kinetics models of cefuroxime axetil under different conditions. The model parameters were obtained by regression, and the half-life(t1/2) was predicted. The degradation mechanism of cefuroxime axetil was analyzed from the molecular scale by Materials Studio simulation software. The results show that the degradation of cefuroxime axetil acetone solution under the above conditions is in line with the first-order reaction kinetics. When pH is lower than 9.54, cefuroxime axetil acetone solution is basically stable. When pH is higher than 9.54, the chemical stability of cefuroxime axetil acetone solution becomes worse, the degradation rate increases rapidly, and the color of the solution becomes darker with the increase of pH value. The chemical stability of cefuroxime axetil acetone solution decreases with the increase of temperature. The research result provides data support for production process, crystallization process design, storage and application.
2020, 41(4):349-355. DOI: 10.7535/hbkd.2020yx04008
Abstract:In order to improve the survival rate and the clinical treatment effect of breast cancer patients, the pathogenic genes of breast cancer were studied from the molecular mechanism. At first, the differential expression of 113 normal tissues and 1 109 cancer tissues was analyzed. Then, the complementary genes were grouped in a conditional joint analysis method for differentially expressed genes, and a set of gene fitting prognostic models were selected by stepwise Cox regression. The results show that six genes-[WTBX]VWCE, SPDYC, CRYBG3, DEFB1, SEL1L2 and NMNAT2-have a harmful effect on survival rate. Four genes AMZ1, GJB2, CXCL2 and ALDOC are beneficial to survival rate. The final prognostic model of the 10 genes can significantly divide the samples into high-risk group and low-risk group, and predict the 5-year and 10-year survival rates of breast cancer patients, and the time-dependent AUC values are both up to 0.7 or more. This method can take advantage of the correlation between genes to reduce dimensionality of high-dimensional data and eliminate the problem of collinearity between genes. The prognosis model of these 10 genes can provide help for the clinical prediction of patients.
2020, 41(4):356-364. DOI: 10.7535/hbkd.2020yx04009
Abstract:To solve the problem of higher selected seismic effect value caused by the ductility of eccentrically braced steel structures, the seismic performance of the eccentrically braced structure with shear multi-links was studied. On the basis of the test model, the link cross section was designed into a multi-link model based on the constant shear area of the link web. Then eight multi-link numerical models were established by using ABAQUS finite element, and monotonic loading analysis and cyclic loading analysis were performed respectively. The changes of failure modes, hysteresis curve, bearing capacity, stiffness and energy dissipation capacity with the number of links were analyzed. The results show that the plastic deformation of the link is fully developed, which effectively protects other non-energy dissipation members; the bearing capacity, yield displacement and energy dissipation capacity of the structure are better than those of the single link mode; The difference in initial stiffness of each multi-links model is within 4%, which is smaller than that of single-link model, but the multi-link model can delay the degradation rate of stiffness. The proposed model can improve the seismic performance and has some reference for actual engineering application.
2020, 41(4):365-373. DOI: 10.7535/hbkd.2020yx040010
Abstract:China is a major agricultural country, and the production of agricultural waste is increasing year by year. However, the utilization rate of resources is still low. Anaerobic dry fermentation technology is mainly used to treat solid organic matter with a total solid content of 20%~40%(wt). It is an effective way to recycle agricultural waste resources, which has the advantages of low water consumption and high volumetric gas production rate. Due to the high solid content, there are still some problems in the anaerobic dry fermentation technology, such as slower reactor start-up, difficulty in mixing materials, and poor heat and mass transfer. Therefore, the innovation of anaerobic dry fermentation equipment and optimization of process parameters will directly affect the further promotion and application of this technology. The research and application status of anaerobic dry fermentation technology at home and abroad in recent years were summarized, the operating characteristics of typical batch and continuous anaerobic dry fermentation reactors were compared, and the effects of main process parameters on anaerobic dry fermentation were analyzed. The shortcomings of the current anaerobic dry fermentation technology were presented, and the future development trend of the technology was prospected in terms of technical equipment and process research, which is to develop design methods for key links in anaerobic dry fermentation equipment, and to carry out in-depth research on mechanisms, such as biogas residue rheological properties and microbial dynamic changes, etc.
2020, 41(4):374-380. DOI: 10.7535/hbkd.2020yx04011
Abstract:In order to explore the action mechanism of aquatic organisms affected by quinolones, two typical quinolone antibiotics, ofloxacin and norfloxacin, were selectedto expose scenedesmus obliquus and zebrafish in their solutions. After 5, 10 and 15 days, the effects of ofloxacin and norfloxacin at the mass concentrations of 0, 30, 60, 120, 360 mg/L on SOD and CAT oxidative stress indexes in zebrafish and scenedesmus obliquus were detected and compared, respectively. The results show that quinolone antibiotics have a similar effect on the SOD activity of zebrafish and scenedesmus obliquus, which indicates that the effects on SOD activity of zebrafish and scenedesmus obliquus are basically the same.The effects of quinolones on CAT activity of zebrafish and Scenedesmus obliquus present different trends, which indicates that different aquatic organisms have different abilities to maintain the balance of cellular antioxidant environments. The maximum and minimum values of SOD and CAT activities influenced by quinolone antibiotics in zebrafish test group are both higher than those of in scenedesmus obliquus test group, which shows there are significiant differences in SOD activity and CAT antioxidant stress response intensity between zebrafish and Scenedesmus obliquus. The results provide a scientific basis for further research on the ecological toxicity effect of quinolones on aquatic organisms.