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(5):381-389. DOI: 10.7535/hbkd.2020yx05001
Abstract:In order to solve the single machine scheduling problem, and improve the reliability and stability of the equipment, a single machine scheduling model considering piecewise linear deterioration and maintenance unavailability time was established according to the characteristics of continuous fault detection and discrete fault detection. Based on the system reliability theory, the single machine scheduling problem considering machine reliability was studied, and the advantages and disadvantages of maintenance strategy were compared by unified processing of decision conditions. The influence of related parameter changes on production scheduling optimization was determined by single factor and two factor adjustment analysis. The results show that the solution time of the model increases exponentially with the decreasing direction of unit delay cost, and the greater the unit delay cost, the faster the solution speed. The change of delay cost per unit time will not cause a significant change in maintenance cost, and the cost function does not have jumping nodes in flexible periodic maintenance, so it can not be adjusted adaptively. Ratio of preventive maintenance time to fault minor maintenance time has great influence on maintenance decision under discrete detection. The unified processing method of decision conditions can reduce the calculation time and detection cost, and better solve the problems of excessive maintenance or insufficient maintenance in discrete fault detection. These will help to reduce operating costs and improve economic benefits.
2020, 41(5):390-398. DOI: 10.7535/hbkd.2020yx05002
Abstract:The structure design scheme and the control method of a self-balancing cockpit system based on the principle of dual-axis gyro were proposed to solve the problem of improving maneuverability of special carrier platform under large roll and pitch motions. First, the structural modeling of the self-balancing cockpit system was completed by Creo, and the movement model was built in ADAMS/View in combination with the road model and the driving system of the vehicle. The three-dimensional model of the cockpit was decomposed and mapped into two planes that embody the dynamics of roll and pitch, and the dynamic mathematical model was formed respectively. Then a self-balancing control strategy for real-time correction of the cockpit attitude was designed. Second, considering the influence of different types of roads on the attitude of the cockpit, a control threshold module based on the load transfer rate was designed to clarify the working range of the self-balancing control algorithm. Finally, the Simulink-ADAMS self-balancing control joint simulation model was built in MATLAB/Simulink environment, and the virtual tests under various working conditions were performed to verify the effectiveness of the control system. The results show that the self-balancing control system can effectively correct the roll angle and pitch angle of the cockpit in real time, and reduce the impact of the vehicle roll and pitch motion on the driver. The self-balancing cockpit system breaks through the performance limitations of the suspension system, and improves the adaptability of the off-road special carrier platform to harsh off-road road surface, which provides a model basis for the simulation verification of self-balancing control algorithm.
2020, 41(5):399-407. DOI: 10.7535/hbkd.2020yx05003
Abstract:Aiming at the problems of non-linearity and variable model parameters of the main steam pressure control system of gas-fired power generation boiler, an improved implicit generalized predictive control strategy was proposed. First, the forgetting factor recursive least square method was used to identify the model parameters, and a discrete mathematical model of the main steam pressure was established. Second, an implicit generalized predictive control system for main steam pressure was established on the basis of conventional generalized predictive control theory, which simplified the control algorithm and improved the robustness of the system by adding a PI structure to the objective function. The simulation results show that, compared with the cascade PID and conventional implicit generalized predictive control, the proposed control strategy reduces the adjustment time by 20 s at most when the model is adapted; the overshoot decreases by up to 5.08% and the adjustment time decreases by up to 36 s when the model is mismatched, and the system robustness and anti-interference ability are improved. The engineering application shows that the main steam pressure control deviation is within ±0.2 MPa, and the control accuracy is significantly improved in the proposed strategy. The improved implicit generalized predictive control has high research and application value in the main steam pressure control in industrial production.
2020, 41(5):408-415. DOI: 10.7535/hbkd.2020yx05004
Abstract:In order to improve the smoothness and stability of the motion of the cable-driven continuum robot, the trajectory planning methods based on spline function and particle swarm optimization algorithm were proposed for the cable-driven continuum robot in its joint space and Cartesian space respectively. Firstly, the kinematic model was established by applying the local product-of-exponential(POE) formula with two parameters. Secondly, the inverse kinematics was solved by Newton Raphson iterative method. Finally, the particle swarm time optimization algorithm based on adaptive inertia weight combing with the quintic B-spline function was used to realize the trajectory planning of the continuum robot in joint space and Cartesian space respectively. The simulation results show that continuous trajectories can be obtained both in joint space and Cartesian space under the same conditions, the obtained velocities are less than 10 mm/s, and the accelerations are less than 20 mm/s2.The joint displacement, velocity and acceleration curves are smoother in joint space, which takes 9.219 3 s, while it takes 10.604 6 s in Cartisian space. The research on trajectory planning of a cable-driven continuum robot based on particle swarm optimization algorithm improves the kinematic performance of the continuum robot and provides references for pose planning of the cable-driven continuum robots.
2020, 41(5):416-423. DOI: 10.7535/hbkd.2020yx05005
Abstract:To improve the correctness of data race detection, an approach to the data race detection based on the context-sensitive analysis in multithreaded programs was proposed. Firstly, control flow analysis was used to construct context-sensitive call graphs, and then escape analysis was employed to find thread-escaped objects that may cause data race. Secondly, context-sensitive alias analysis was conducted to reduce false positives and false negatives. Finally, the happens-before analysis was performed to remove false positives caused by ignoring thread interactions. A data race detection tool ConRacer was implemented in WALA framework based on this approach and was compared with the existing tools SRD and RVPredict. The experimental results show that ConRacer is the most precise tool compared with SRD and RVPredict and it can not only detect data races, but also reduce false positives and false negatives effectively. ConRacer improves the detection accuracy by combining context-sensitive with static detection methods, which has certain reference value for discovering concurrent errors and optimizing software performance.
2020, 41(5):424-432. DOI: 10.7535/hbkd.2020yx05006
Abstract:In order to solve the problem of imbalance of data samples in multi-modal data, the resource-rich text modal know-ledge was used to model the resource-poor acoustic mode, and an emotion recognition neural network was constructed by using the similarity between auxiliary modes to supervise training. Firstly, the neural network with bi-GRU as the core was used to learn the initial feature vectors of the text and acoustic modalities. Secondly, the SoftMax function was used for emotion recognition prediction, and simultaneously a fully connected layer was used to generate the target feature vectors corresponding to the two modalities. Finally, the target feature vector assisted the supervised training by calculating the similarity between each other to improve the performance of emotion recognition. The results show that this neural network can perform four emotion classifications on the IEMOCAP data set to achieve a weighted accuracy of 82.6% and an unweighted accuracy of 81.3%. The research result provides a reference and method basis for emotion recognition and auxiliary modeling in the multi-modal field of artificial intelligence.
2020, 41(5):433-441. DOI: 10.7535/hbkd.2020yx05007
Abstract:In order to increase yield,take the Bacillus subtilis Asr as the expreession strain, the fermentation process of Bacillus subtilis Asr was optimized by orthogonal test and response surface method. The results show that three main factors affecting bacterial yield are leaching yeast powder, MgSO4 and CaCl2. The best fermentation medium formulation is as following: sucrose 20 g/L, peptone 10 g/L, leaching yeast powder 8.65 g/L, K2HPO4 3.0 g/L, MgSO4 0.27 g/L and CaCl2 0.53 g/L. The optimal culture conditions are as following: 37 ℃, initial pH 7.0, inoculum of 10% and stirring speed of 250 r/min. After the optimization, the highest yield of Bacillus subtilis Asr reaches 7.30×108 cfu/mL, which is 3.95 times higher than that before optimization. The study provides a technical reference for the subsequent bacterial scale-up culture in fermentor and the optimization of fermentation medium from other Bacillus subtilis.
2020, 41(5):442-454. DOI: 10.7535/hbkd.2020yx05008
Abstract:To scientifically measure and accurately evaluate the spatial quality within the station area and realize effective optimization, seventy-three subway stations in Chengdu City were selected to support multi-source big data such as street network, POI(point of interest), street view pictures, etc., then machine learning and spatial design network analysis(sDNA) and other technologies were used to construct an evaluation system with convenience, functionality and comfort as the core. Large-scale quantitative evaluation of street space quality within the station area was carried out, and guidance and control strategies for different levels of stations were proposed. The results show that 68.03% of the station area streets score is lower than the medium level, the street function and comfort are generally good, and the convenience is poor; at the station level, the street space quality shows the distribution characteristics of high in the South and low in the north, high in the West and low in the East, and high in the inside and low in the outside. The proposed method takes into account the analysis accuracy of human-oriented scale, the analysis depth of site scale and the analysis breadth of urban scale, which is helpful to create an efficient dynamic feedback mechanism of urban management.
2020, 41(5):455-461. DOI: 10.7535/hbkd.2020yx05009
Abstract:In order to study the effect of anisotropy on the safe service of B+F dual-phase X80 pipeline steel, the slow strain tensile and polarization behaviors of hot rolled ferrite + bainite dual-phase X80 pipeline steel at three angles(0°, 45° and 90°) with rolling direction were analyzed by metallography, scanning electron microscopy, slow strain tensile test and electrochemical polarization method in simulated seawater. The result shows that the dual-phase X80 pipeline steel is composed of polygonal ferrite and lath bainite, and the content ratio of ferrite and bainite is about 1∶1. The slow tension yield strength of X80 pipeline steel with different angles from rolling direction decreases significantly with the increase of sampling angle in simulated seawater environment, which indicates that seawater has obvious stress corrosion to X80 pipeline steel; the slow strain tensile stress-strain curve of B+F dual-phase X80 pipeline steel parallel to rolling direction(0°) shows dome shape, the yield strength and tensile strength are the highest, the yield strength ratio is 0.81, and the uniform elongation is 13.4%, which can meet the application requirement; the self-corrosion potential of B+F dual-phase X80 pipeline steel perpendicular to the rolling direction(90°) is the most negative and the self-corrosion current is the largest, which indicates the seawater corrosion resistance is the worst; the corrosion resistance of dual-phase pipeline steel in the direction of 45° from the rolling direction in simulated seawater is the best due to the most positive self-corrosion potential. The research on the slow strain tensile anisotropy of B+F dual-phase X80 pipeline steel in simulated seawater environment can improve its safe service, and has some reference value for the actual production of large deformation pipeline steel.
2020, 41(5):462-467. DOI: 10.7535/hbkd.2020yx05010
Abstract:In order to solve the problems of segregation defects in ZL205A alloy castings and clarify the influence of vibration on segregation structure and hardness, the electromagnetic vibration table was adopted as the vibration source to study the effects of vibration frequency, amplitude and time on segregation structure proportion and hardness of the alloy. The results show that the proportion of segregation structures decreases first and then increases, and the hardness increases first and then decreases with the increase of vibration frequency from 25 Hz to 55 Hz. When the vibration amplitude increases from 1 mm to 4 mm, the proportion of segregation structures decreases gradually and tends to be stable, and the hardness decreases first and then increases. With the increase of vibration time from 30 s to 75 s, the proportion of segregation structures increases and finally tends to be stable, and the hardness decreases first and then increases. Therefore, the vibration frequency has the most significant effect on segregation structure and hardness of the alloy, followed by time and amplitude. In addition, the precipitation of segregation structures also affects the hardness of the alloy. The results provide a theoretical reference for studying the change rule of solidification structure of ZL205Aalloy under vibration condition and for improving casting quality.
2020, 41(5):468-476. DOI: 10.7535/hbkd.2020yx050011
Abstract:In order to deeply treat pharmaceutical wastewater to meet the industrial water quality standard, the membrane flux change of the comprehensive pharmaceutical wastewater treated with advanced nanofiltration and reverse osmosis was studied. The operating condition, flux and water yield rate were studied in continuous and cyclic modes. According to the change of membrane flux, the treatment and cleaning scheme suitable for industrial application of membrane separation were determined. The results show that the daily physical wash time of nanofiltration membrane is 7 minutes, the wash time of intensive acid and alkali is 90 minutes respectively, the average flux is 16.1 L/(m2·h) in continuous mode and 7.7 L/(m2·h) in cyclic mode, and the water recovery rate is 73%. The daily physical wash time of reverse osmosis membrane is 12 minutes, the wash time of intensive acid and alkali is 90 minutes respectively, the average flux is 12.8 L/(m2·h) in continuous mode and 7.2 L/(m2·h) in cycle mode, and the water recovery rate is 74%. The research on advanced membrane treatment of pharmaceutical wastewater provides a theoretical basis for the industrial application.