Abstract:This paper presents an integrated vehicle chassis robust controller with fewer calibration parameters and faster dynamic response for the integrated control problems of active front wheel steering subsystem and direct yaw moment control subsystem, based on the fast terminal sliding mode control theory. Firstly, a vehicle dynamic model with lateral and yaw degrees of freedom is established based on D 'Alembert principle, and it is used as an integrated vehicle chassis control model. Then, an active front wheel steering control law and a direct yaw moment control law are designed based on the fast terminal sliding mode control theory, respectively. A smooth switching rule is established based on smooth switching factor defined by the phase plane of the vehicle sideslip angle and its derivative to realize the smooth switching control between the active front wheel steering subsystem and the direct yaw moment control subsystem. Meanwhile, the smooth switching rule can confine the main working areas of the active front wheel steering subsystem and the direct yaw moment control subsystem to the linear and non-linear areas of the tires, respectively. Finally, the feasibility and effectiveness of the proposed integrated vehicle chassis robust controller are verified based on vehicle dynamics simulation software. The results show that the proposed controller can take into account both vehicle handling stability and ride comfort.

Abstract:Aiming at the problem of parameter selection and intention stage determination of intention representation in lane change intention identification， a new combined method is proposed. On the basis of the original parameters obtained from the driving simulator， the C4.5 decision tree algorithm and Pearson correlation analysis are used to obtain the parameter group which is composed of steering wheel angle， lane departure and yaw acceleration with high importance and low correlation. On this basis， K-means clustering is applied to the time series of steering wheel angle and lane departure to determine the driver's lane change intention stage. It is concluded that the length of intention stage is approximately linear related to the average speed， and the length of left lane change intention stage is larger than that of right lane change intention stage. Finally， the continuous Gaussian hidden Markov model is established， and the lane change intention recognition model and lane keeping recognition model are trained on the basis of intention representation parameter group and intention stage data. The average off-line recognition accuracy of the model is 90%. The driver's left lane change intention can be judged 1.5 s before the start of left lane change， and 1.4 s before the start of right lane change. The results show that the intention recognition model based on the intention representation parameters and intention stage can effectively identify the driver's lane changing intention， and the recognition accuracy is high and the timing is strong. This method can provide reference for intention parameter selection and intention stage determination in intention recognition research.

Abstract:In order to solve the fatigue life calculation problem of engineering machinery complex machine-liquid structure, this paper proposed a calculation method for structure fatigue life based on mechanical and hydraulic co-simulation technology, taking the scissor mechanism of a scissor aerial work platform as the research object. A multi-body dynamics simulation model of mechanical-hydraulic combined rigid-flexible coupling of scissor mechanism was established, and the force status in the lifting process of scissor mechanism was also analyzed. The ultimate working status was determined at the lifting stage of 79.2 s, while the load spectrum at each key hinge point was extracted. Under the same working status of simulation, the test experiments of oil cylinder pressure and structural stress were carried out. The experimental results verified the correctness of the dynamics simulation. Then, according to the load spectrum of the hinge point and the ultimate working status confirmed by co-simulation, the static analysis of scissors arms under the ultimate working status and unit loading action was carried out to obtain the static stress distribution of scissors arms structure. Eventually, by using the hinge point load spectrum and the static stress distribution, the fatigue damage and fatigue life of scissor arms were obtained. The results confirmed that the most hazardous part of scissors arms fatigue was the connecting position of each part of scissors arms, which provided a basis for subsequent fatigue life optimization.

Abstract:A high damping vibration isolator with nested X-type structure is proposed for the first time in order to achieve the high damping output vibration isolation of isolators without reducing stiffness. On the basis of the established dynamic model of vibration isolation system, firstly, the equivalent damping of vibration isolation system is derived, and its nonlinear variation characteristics are studied. Then, the harmonic balance method is used to obtain the force transmissibility of the vibration isolation system. Based on the force transmissibility, the performance of vibration isolation and the sensitivity of design parameters are analyzed. Finally, the validity of the theoretical model and the accuracy of the analytical results are verified by the performing experiments. The results show that, compared with the conventional linear isolators，the nested X-type structure high-damping isolator with the same design parameters can greatly improve the damping output, and its isolation characteristics can be flexibly adjusted by various design parameters. The research results can provide theoretical basis for the design and application of high damping vibration isolators.

Abstract:In order to analyze the influence of the hyper-damping isolator on the dynamic characteristics of elastic beam, the dynamic mechanical models of the beam on single-layer and two-layer continuous elastic foundation were presented, respectively. The dynamic responses of the elastic beam under harmonic steady excitation were given in space-frequency domain. For comparison, the definition of force transmission ratio and vibration decay rate along the vertical and horizontal direction of the elastic beam were provided, respectively. Then, the control effectiveness of the hyper-damping isolator on the dynamic characteristics of the beam on the elastic foundation was evaluated. The calculating results show that the amplitude of the transmission force rate and decay rate of the flexural wave in space domain can be enhanced by using the hyper-damping isolator when compared with the common linear elastic foundation. Besides, the system frequency of the beam with hyper-damping isolator was higher than the beam on elastic foundation. Finally, the effective working frequency range, the amplitude of the transmission force rate and the vibration decay rate of the beam can be optimized by adjusting the parameters of stiffness ratio ε and the safe coefficient α of the hyper-damping isolator.

Abstract:To quantify the uncertainty of wind turbine airfoil aerodynamic performance under random fluctuation of natural wind, a stochastic numerical analysis model for the aerodynamic characteristics of wind airfoil based on the Transition SST model combining the non-intrusive probabilistic collocation method was established for the S809 airfoil. The determined and uncertain components of aerodynamic characteristics of S809 airfoil under natural wind conditions were obtained. The effects of wind speed and direction uncertainty on the flow field structure, pressure coefficient, friction distribution, and turbulence kinetic energy were quantitated and the uncertainty propagation mechanism was revealed. The results show that the influence of stochastic wind speed and direction on the uncertainty of airfoil lift drag aerodynamic factor is significant. The maximum relative uncertainty of the 3σ confidence interval of lift drag ratio for S809 airfoil within the range of calculated attack angle is ± 35.13%. The uncertainty of lift drag ratio under the coupling effect of stochastic wind speed and direction is 4.76 times and 1.08 times that with single stochastic factor, respectively. The uncertainty sensitive region is observed at the leading edge. Aerodynamic stability optimization design is recommended on the leading edge of the airfoil.

Abstract:Based on phase-field model，brittle fracture of the structures under tension is studied numerically. An introduction for construction of crack distribution function and energy dissipation function is presented. The governing equations for the phase field model are derived according to the conservation of energy and further solved by alternating minimization (staggered) algorithm. Good agreements between analytical solutions and numerical solutions of one-dimensional bar under tension validate the accuracy of analytical solutions. Numerical simulations of structures with geometric imperfection and predefined damage under tension are also presented. The numerical results show that deformation localization and brittle fracture in failure areas can be modeled accurately.

Abstract:Stability of manufacturing process is the basic for the company to guarantee the produce quality. In view of the lack of systematic and comprehensive quantitative analysis tools in the past process management, a multi-index quantitative evaluation system for manufacturing process is established. The influence factors on manufacturing process are analyzed and evaluated, and the calculation steps of process factor expectation index and manufacturing process expectation index are given based on the hesitant fuzzy theory and multi criteria decision making method. The production state of manufacturing process is expressed quantitatively by the rating scale. Case analysis shows that the method can help managers to evaluate the manufacturing process status intuitively and effectively, and provide more dimensional management data for enterprises in digital production construction.

Abstract:Six single-phase four-column transformers of 20 kVA，220 V，and short-circuit impedance of 18% （only as the body of the transformer） connected with two sets of 6-pulse rectifier bridges were regarded as 12 pulse rectifier devices to simulate the rectifier stations in the HVDC transmission system. The noise of single-phase converter transformer was measured by means of the experimental method under various conditions. Through the analysis of the experimental data，it is concluded that the higher harmonic voltage of the valve side winding is the main factor leading to the vibration and noise of the converter transformer. The shunting capacitor at the valve side was proposed to reduce high-order harmonic voltage of valve side，as well as the vibration and noise of converter transformer. The experimental results show that this proposed method is effective in noise reduction.

Abstract:Aiming at the problem that the Maximum Torque Per Ampere（MTPA） current control of the Interior Permanent Magnet Synchronous Motor （IPMSM） is affected by the change of motor parameters，this paper proposes an improved adaptive disturbance observation MTPA control strategy. This method uses the stator current vector angle as the disturbance，and compares the current amplitudes before and after the control system to determine the search direction. By integrating adaptive PI control into the disturbance observation method，the tracking system randomly selects the corresponding disturbance step length，thus this method solves the dynamic and steady-state performance，improves the accuracy and system operation efficiency，overcomes the traditional MTPA control method's dependence on motor parameters，and improves the overall efficiency of the system. In addition to the search accuracy of the current vector angle，this paper considers the influence of external factors on the changes of parameters such as inductance and flux linkage to obtain the optimal current vector angle under the dq axis of the built-in permanent magnet motor（IPMSM）. The simulation and test results show the effectiveness of the proposed method.

Abstract:Due to the complex mechanism of the effect of micro-source switching on interactive stability between the grid and the micro-grid with series micro-source inverters, traditional methods were difficult to model and can't make decision in time. In this study, therefore, an assessment method of interactive stability based on gradient boosting decision tree (GBDT) was proposed. Firstly, the feature functions of the micro-source switching were constructed to extract the position feature which existed typically in series structure system modulated by carrier phase shifted SPWM. The proposed functions can reduce the feature dimension, thus improving the efficiency of assessment model and making the model migration capable by feature fitting. Secondly, the assessment of interactive stability was treated as a multi-classification task and the resonant frequency bands of instable samples were predicted. Thus, the different strategy can be taken according to the classification and prediction. Finally, the tests on validation data sets and new test sets verified the correctness and effectiveness of the feature construction functions which can provide references for the similar series structure system in power quality analysis, optimal operation and other aspects. The results also verified the high generalization performance and practicality of the proposed assessment model, which can provide a new tool for on-line stability analysis and decision-making of grid-connected operation systems.

Abstract:In order to meet the reactive power demand of new energy power stations, an LC series filter converter is proposed in this paper. Taking the three-phase 380 V / 30 kW grid converter as an example, compared with the traditional L and LC filter structure, the proposed converter structure can reduce about 71% of the original converter system DC voltage and release 12% of the active capacity while maintaining the converter output reactive power capacity. And the efficiency is improved by 6% when compared with the original filter structure. In addition，based on the discrete state model of LC converter, a state control method based on LC series filter type converter is proposed, which effectively improves the system damping of LC series filter at the resonant frequency. Finally, a simulation model of LC converter is established in PSIM to verify the advantages of LC filter converter and the feasibility of the state feedback control strategy.

Abstract:As the power of hydroelectric power generation and photovoltaic power generation systems are frequently fluctuated and have poor stability, a multi-port converter and its energy cooperative control scheme are proposed for new energy access. Firstly, the common topologies of multi-port converters are compared and analyzed, and one of the multi-port converters is selected. Secondly, for the general problem of energy complementation of a variety of renewable energy (such as light, water and wind etc.), a multi-mode energy control cooperative strategy is proposed based on multi-port converters. Finally, the running status under multiple working conditions is simulated, and the simulation results show that the two-layer control strategy can effectively execute the energy coordination and scheduling, which can alleviate the seasonal overload problem in the region vividly. Therefore, the multi-port converters show strong adaptability for the control of the DC bus voltage and output power.

Abstract:The electrical anisotropy of rock is characterized by conductivity tensor. The four-pole method and six-pole method are mostly used to measure rock conductivity in the laboratory，but it is difficult to fill the nine components of conductivity tensor in one experiment. And multiple experiments are easy to cause large measurement errors. For this reason，based on the existing document，this paper designs a conductivity tensor measuring instrument for square sample cores. This solution is also suitable for plunger cores. The completely water-saturated core is replaced by nitrogen. The temperature control system and the confining pressure control system control the temperature and pressure inside the core holder. The upper computer control electrode can be used to measure the core conductivity tensor at different water saturations. The instrument can also be used for rock electrical experiments of plunger cores. Through the measured conductivity data，the unknown coefficients of Archie’s formula can be determined. Through the analysis on theoretical and experimental data，the feasibility of the design scheme of the conductivity tensor measuring instrument is verified.

Abstract:In high terrestrial stress regions, rockburst is a major geological disaster significantly influencing the underground engineering construction. How to carry out the efficient and accurate rock burst prediction remains to be solved. In order to comprehensively consider the objective information of index data and the important role of subjective judgment and decision-making in rockburst prediction, the improved analytic hierarchy process and the CRITIC method based on index correlation are used to obtain the subjective and objective weights of each index, respectively. Fusion is carried out to obtain the comprehensive weight according to the principle of minimum discriminative information. The original cloud model and the classification interval of the predictive index are revised to make up for the excessive sensitivity of original cloud model to the average of the grade interval. A hierarchical comprehensive cloud model of each index is generated through a cloud algorithm. Finally, the reliability and validity of the model are verified by rockburst examples. The model in this paper is compared with the entropy cloud model, the CRITIC cloud model and the set pair analysis multi-dimensional cloud model. The results show that the model can not only describe the various uncertainties of interval value indicators, but also quickly and effectively determine the rockburst strength level.

Abstract:In this study，o-CP，m-CP and p-CP were selected as the target pollutants, and then the performance and mechanism of electroreductive dechlorination of mono-chlorophenols on inert（GC） and catalytic（Ag and Pd） electrodes were studied by cyclic voltammetry（CV）. In addition, this study also explored the impact of molecular structure on the process of electrochemical reduction of mono-chlorophenols. The results showed that all the obtained values of k of these three types of mono-chlorophenols from GC electrode were all greater than 0.5, indicating that reductive cleavage of C-Cl bond on GC electrode followed a stepwise mechanism. Nevertheless, a noticeable positive shift of the reduction peak potential of mono-chlorophenols on Ag and Pd electrodes was observed. Pd exhibited excellent electrocatalytic properties towards dechlorination of mono-chlorophenols. Moreover, the involved values of k on catalytic electrodes（Ag and Pd） were far less than 0.5，which indicated that reductive cleavage of C-Cl bond followed a concerted mechanism. This research further showed that the electrocatalytic dechlorination reactivity of these three types of mono-chlorophenols followed a descending trend as p-CP>m-CP>o-CP. This phenomenon was mainly due to the existence of steric hindrance, which made it the most difficult for chlorine atom at ortho-position to combine with the electrode surface. In addition, the values of the lowest unoccupied molecule orbital energy（ELUMO） of these three types of mono-chlorophenols followed a descending order as: o-CP>m-CP>p-CP, indicating that the reductive dechlorination of mono-chlorophenols followed the opposite order. Finally, based on the molecular structure characteristics of mono-chlorophenols, the parameter ELUMO was selected and successfully developed a good linear free energy relationships（LFERs） with the electroreductive dechlorination reactivity in this research.

Abstract:With the development of the chemical industry, nitrogen-containing heterocyclic compounds constantly enters the environment, which increases the threat to the ecological environment. The degradation characteristics of the nitrogen-containing heterocyclic compounds 2，6-dichloropyridine（2，6-DCLPY） in chemical wastewater by UV/H2O2 were investigated, and the concentration of 2，6-DCLPY in the degradation process was determined by ultraviolet spectrophotometry. The influencing factors of 2，6-DCLPY degradation reaction including initial 2，6-DCLPY concentration，H2O2 concentration, pH and coexisting anions were studied. The results showed that the degradation of 2，6-DCLPY under UV/H2O2 system accorded with quasi-first-order reaction kinetics. Hydroxyl radical （·OH） was the main active substance for degradation of 2，6-DCLPY, while UV played a synergistic effect. The degradation efficiency of 2，6-DCLPY gradually increased with the increasing H2O2 dosage, and the highest degradation rate could reach 77.3% when the molar ratio of H2O2 and 2，6-DCLPY was 37 ∶ 1 and the pH was 7.2. The coexisting anions HCO3- and NO3- can directly react with ·OH, which leaded to significant inhibitory effect on the degradation reaction. The presence of electron-donating groups such as amino groups on the pyridine ring is conducive to the degradation of pyridine pollutants，while electron-withdrawing groups such as chlorine inhibits the degradation of pyridine pollutants.