Editor in chief：朱立光
International standard number：ISSN 1008-1542
Unified domestic issue：CN 13-1225/TS
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2019, 40(6):461-468. DOI: 10.7535/hbkd.2019yx06002
Abstract:Typical curb recognition algorithms have difficulty in balancing real-time performance and reliability. In this paper, with a multi-line LiDAR used, a curb recognition algorithm based on geometric features and 3D point cloud features of curb areas is proposed, which reaches a tradeoff between real-time performance and reliability. Faced with the large amount of point cloud data, the algorithm firstly proposes a ground segmentation method based on RANSAC algorithm, filtering out the ground points in the preset region of interest, and then the orderly rasterization of the remaining disordered points is carried out for matching and screening curb areas according to the curb's geometric characters and the points' distribution feature. After that, the least square method fused with RANSAC is proposed to achieve the robust fitting of curb curve. Experiments show that the recognition accuracy of the algorithm is more than 95% in both straight and bend scenes, and the time-consuming is less than 15 ms, which indicates the good accuracy and real-time performance of the proposed algorithm.The algorithm can effectively identify road curb, thus providing a theoretical reference and method basis for intelligent vehicle driving area recognition and its' control.
2019, 40(6):469-476. DOI: 10.7535/hbkd.2019yx06003
Abstract:In order to extend the basic theory of boundary value problems for nonlinear quantum difference equations,the existence of solutions for a class of second order three-point nonlinear q-differential equations with a first order q-differential on a nonlinear interval is studied. Firstly, changing the order of integration formula of double q-integral with infinite limit generalized integral is given and proved. Secondly, the Green function of the boundary value problem of second-order three-point linear q-difference equation on the infinite interval is calculated and the property of Green function is studied. Next, the integral operator T is constructed on the abstract space, and the Leray-Schauder continuous theorem is used to obtain the existence of the solution of the boundary value problems for the second-order three-point nonlinear q-difference equation on the infinite interval. Finally, an example is given to illustrate the validity of the results. The research results have important significance for the development of quantum calculus and its application in the fields of mathematical physics.
2019, 40(6):477-481. DOI: 10.7535/hbkd.2019yx06004
Abstract:In order to discuss the minimum eigenvalue of adjacency matrix in the class of complementary graphs of the tricyclic graph with a given order of n and n－4 pendent vertexes, the unique graph whose minimum eigenvalue reaches the minimum is characterized. Based on the simple undirected connected graph,the minimum eigenvalue of the graph is studied from the structure of the complement graph, and the minimum eigenvalue of the adjacency matrix in the complement graph class of the tricyclic graph with a given order of n and n－4 pendent vertexes reaches the minimum unique graph when the value is [WTBX]λ([WTHX]G[WTBX]([XC符号1.eps;%85%85;P](n-4)/2,(n-4)/2[XC符号2.eps;%90%90;P])C)[WTBZ]. The result shows that the associative graph adjacency matrix is a matrix which represents the adjacency between vertices, and its minimum eigenvalue is the minimum eigenvalue of graph, which can describe the essential properties of graph well. The conclusion from this research shows that the minimum eigenvalue of the complement graph of the tricyclic graph with a given order of n and n－4 pendent vertexes reaches the minimum eigenvalue, which provides certain reference for further study of the minimum eigenvalue of the adjacency matrix in the complement graph class.
2019, 40(6):482-487. DOI: 10.7535/hbkd.2019yx06001
Abstract:In order to expound the influence of sign-changing potential on logarithmic nonlinearity and Hatree nonlinearity. By the variational method, a weak solution to the problem is a critical point of the energy functional. Then, by the logarithmic inequality, the energy functional of Schrdinger problem satisfies the mountain geometry and (PS) condition. The existence of nontrivial solutions is obtained by mountain pass theorem. The research method has good expected results in theoretical proof and laid a good foundation for the study of Schrdinger problem with logarithmic nonlinearity with double sign-changing potential.
2019, 40(6):488-495. DOI: 10.7535/hbkd.2019yx06005
Abstract:The photocatalytic oxidation ability of polyimide is weak because of the relatively low valence band (VB). The valence band potential of the PMDA/PDA linear polyimide is +2.45 eV, showing that it has strong oxidizing property and strong oxidative degradation ability without constructing heterojunction.In order to prepare a kind of polyimide with high visible-light photocatalytic activity，linear polyimide (PI) with strong oxidizability is prepared by two-step method using pyromellitic dianhydride（PMDA） and p-phenylenediamine （PDA） as raw materials and ethanol as co-solvent. The chemical composition, microstructure and photoelectrochemical properties of PI are investigated by scanning electron microscopy (SEM), fourier infrared spectroscopy (FTIR)，UV-vis diffuse reflectometer (UV-vis DRS), fluorescence spectrometer (PL) and X-ray photoelectron spectroscopy (XPS). The band gap width, Homo potential and lowest unoccupied molecular orbital (LUMO) potential of PI are measured.The results show that the main photocatalytic active center of the obtained polyimide is found to be photogenerated holes through a series of experiments. The photocatalytic activity of polyimide is evaluated by photodegradation of Rhodamine B, and the degradation efficiency of the as-prepared polyimide is three times as that of the commonly used photocatalyst g-C3N4. Therefore, PMDA/PDA linear polyimide is a kind of polyimide with high visible-light photocatalytic activity and high photocatalytic stability.
2019, 40(6):496-502. DOI: 10.7535/hbkd.2019yx06006
Abstract:In order to obtain the optimal solution of genetic algorithm for job shop scheduling problem and improve the iteration speed of the algorithm, the improved method of genetic algorithm is studied. The scheduling model is established with the shortest processing time of the workpiece as the target. An adaptive crossover and mutation operator based on probability improvement is proposed to get the optimal solution of the job shop scheduling problem. The elitist retention strategy and the improved adaptive operator are used in the genetic algorithm, to solve solve job shop scheduling problem. The benchmark cases LA01 and FT06 are used as simulation objects. The corresponding Gantt chart and the search process curve are obtained. The simulation results show that the improved algorithm can get the optimal solution more quickly with the unmodified algorithm. The improved algorithm is more efficient and faster. It is feasible to solve job shop scheduling problem, and is more suitable for industrial production.
2019, 40(6):503-511. DOI: 10.7535/hbkd.2019yx06007
Abstract:In order to improve the combustion efficiency of the hot blast stove and improve the automation degree of the hot blast stove temperature control system, a PID control strategy based on RBF neural network tuning is proposed. First, through the combination of the RBF neural network algorithm and the incremental PID controller, the powerful self-learning ability of the neural network is used to adjust the parameters of the incremental PID. Then, based on the conventional hot-blast stove temperature control system, the outer loop was changed to PID control using RBF neural network tuning. In the hot-blast furnace temperature control system, the inner ring takes the opening degree of the gas valve as a variable, and the outer ring takes the dome temperature as a control variable. The improved cascade control is used to optimize the combustion of the hot-blast stove. Matlab simulation analysis and practical application results show that the PID control curve set by the RBF neural network has almost no overshoot, and the anti-interference ability of the system is increased by 50% compared with the traditional PID control. Compared with the traditional manual control, the proposed control strategy makes the original system's ability to suppress interference significantly stronger and more robust. It has good research and application value in hot air furnace temperature control.
2019, 40(6):512-519. DOI: 10.7535/hbkd.2019yx06008
Abstract:In order to research the distribution of temperature field when the heat storage material is different, three heat retainers are selected, which are clay, sand and gravel. Gambit modeling software is used to establish a simple model, five measuring points with different distance to the buried pipe center are selected, and the Fluent simulation software is used to carry out simulation calculation of temperature field of different heat retainers. The temperature variation at the five points is figured out when the distance to the buried pipe center is different while the heat storage material is same and when the distance to the buried pipe center is same while the heat storage materials are different. Finally, it is concluded that, with the same heat storage materials around the buried pipe, the temperature variation trend of each measuring point varies according to the distance to the buried pipe center, and the closer it is, the more obvious temperature variation is. With different heat storage materials around the buried pipe, the temperature variation trend at the same measuring point is basically same and the soil temperature rises every year after the heat taken process is completed. However, the difference in thermal conductivity causes the differences in temperature, heat storage and heat taken during the annual heat storage and heat taken process. The results can provide a theoretical reference for the design of the buried pipes of solar-coupled ground-source heat pump system.
2019, 40(6):520-525. DOI: 10.7535/hbkd.2019yx06009
Abstract:In order to improve the flight quality of UAV, study the hardware-in-the-loop simulation application of UAV control, and form a set of universal UAV flight control law design and hardware-in-the-loop simulation method, the Z-shaped aircraft with complex aerodynamic characteristics is studied. The Z-shaped aircraft can be folded in the direction of the fuselage for easy storage and transportation. According to the shape parameters of Z-shaped aircraft, the aerodynamic data are obtained. On this basis, the longitudinal linear model is established by using the principle of small disturbance linearization. The longitudinal static stability of the model is studied by adding disturbance pulses. The transfer function of each link is selected, the pitch control loop is established, the PID parameters are adjusted, the longitudinal control law is designed, and simulation is conducted by using Simulink and hardware-in-the-loop simulator. The simulation results show that UAV has good static stability, reasonable selection of PID control parameters, small system overshoot and short adjustment time, which can improve the flight quality of UAV. Hardware-in-the-loop simulation can more truly and intuitively reflect the advantages of UAV attitude. The modeling and simulation methods have certain universality and can be applied to other fixed-wing UAVs.
2019, 40(6):526-532. DOI: 10.7535/hbkd.2019yx06010
Abstract:Aiming at the problem of traditional UAV trajectory planning which falls into local optimum easily, and the problem of UAV trajectory planning in complex terrain, a trajectory planning method based on adaptive polymorphic fusion ant colony algorithm is proposed. This study describes the problem of route planning, establishes a mathematical model, and combines the adaptive ant colony algorithm with the polymorphic ant colony algorithm to form a global and local parallel search mode, which improves the ability of the algorithm to find the global optimal value. An adaptive parallel strategy and an adaptive information update strategy are proposed to improve the global search ability. Simulation results show that this method has better performance than the other two traditional ant colony algorithm and polymorphic ant colony algorithms. It can effectively improve the length and convergence speed of the search path and avoid falling into local optimum in the solution process. Therefore, the adaptive polymorphic fusion ant colony algorithm has a good application prospect in solving the optimal track planning problem.
2019, 40(6):533-539. DOI: 10.7535/hbkd.2019yx06011
Abstract:Pedestrian detectors based on convolutional neural networks generally adopt image recognition network, which usually causes the following problems:1) multi-pool layers lead to the loss of feature information of small target pedestrian; 2) the single pool method leads to the weakening or even loss of the local important feature information of pedestrians. Therefore, based on the maximum pooling and average pooling methods, an adaptive pooling method is proposed, and combined with the Faster R-CNN, an effective pedestrian detector is formed, so as to enhance the local important feature information of pedestrians and retain the effective feature information of small target pedestrians. Through a large number of experiments on several public pedestrian datasets, the results show that compared with the traditional convolutional neural network pedestrian detector, the proposed method reduces the miss rate by about 2%~3%, which verifies the effectiveness of the method.
2019, 40(6):540-547. DOI: 10.7535/hbkd.2019yx06012
Abstract:Aiming at the problem of insufficient feature extraction and low recognition rate of convolutional neural network, a novel facial expression recognition method based on multi-feature fusion convolutional neural network is proposed. First, to increase the width and depth of the network, Inception architecture is introduced into the network to extract the diversity of features; Then, the extracted high-level features are fused with the low-level features, and the pooled features are used to send the fused features into the full connection layer, then the fused features are processed to increase the non-linear expression of the network and enrich the features learned by the network. Finally, the output layer classifies the expressions by Softmax classifier, conductes experiments on FER2013 and CK+, and analyzes the experimental results. Experimental results show that the improved network structure improves the recognition rate of facial expressions in FER2013 and CK+ data sets by 006% and 225%, respectively. The proposed method is valuable for setting up convolution neural network and parameter configuration in facial expression recognition.
2019, 40(6):548-554. DOI: 10.7535/hbkd.2019yx06013
Abstract:In order to study the toxic effects of tetracycline on algae, Selenastrum capricornutum is selected as the test organism. The growing situation, chlorophyll a contents, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and reactive oxygen species (ROS) level in the cells of Selenastrum capricornutum after 0, 02, 04, 08, 16, 32 mg·L-1 tetracycline exposured are studied by indoor test method. The results show that the tetracycline can strongly inhibit growth of Selenastrum capricornutum and the 50% effective concentration (EC50) is 3.142 mg·L-1 during 96 h exposured. Tetracycline treatment inhibits the content of chlorophyll a in the cells of Selenastrum capricornutum. During 96 h exposure period, with the increase of tetracycline concentrations, the activity of SOD shows a "Bell-shaped" trend, the content of MDA and the level of ROS shows an upward trend. The study indicates that tetracycline can cause oxidative stress and damage the antioxidant system in Selenastrum capricornutum cells. Tetracycline poses a potential risk to aquatic ecosystems.