26 research outputs found

    Linear Quadratic Optimal Control with the Finite State for Suspension System

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    The control algorithm could greatly help the suspension system improve the comprehensive performance of the vehicle. Existing control methods need to obtain the intermediate states, which are difficult to obtain directly or accurately when estimated by filters or observers. Thus, this paper proposed a new practical finite state LQR control method to deal with this problem. By combining with the output state of the finite sensor of the vehicle suspension system and weakening the unknown state as the goal, an optimization model is established with the design variables as the LQR weight coefficients. Then, the direct relationship between the current control input and the finite sensor output is obtained, and the finite state LQR control is realized. Taking the quarter-car suspension model as an example, the corresponding noise is added considering sensor accuracy, and the control performance of the four control methods is studied considering the uncertainties of suspension system parameters. In addition, the acceleration of sprung mass and the dynamic travel coefficient of suspension have been separately calculated by methods of finite state LQR control, LQR control, and PID control. The results show that there is not much difference between them under shock excitation or random excitation. However, the finite state LQR control method has the best comprehensive control performance in that its dynamic tire load coefficient is better than other methods; it could take into account the suspension work stroke coefficient, dynamic tire load coefficient, and sprung mass’ acceleration of the vehicle suspension system at the same time. In order to realize the optimal control effect with limited sensor arrangement, the finite state LQR control method only needs to obtain the current sensor output and the current control input, without estimating the unknown intermediate state. By this means, the proposed control method greatly simplifies the design of the control system and has great advantages on practical value

    Brain Network Research of Skilled Shooters in the Shooting Preparation Stage under the Condition of Limited Sensory Function

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    Shooting is a sport dominated by psychological factors. Hence, disturbing the shooter’s sensory function during aiming will seriously affect his psychological state and shooting performance. Electroencephalograph (EEG) measurements of 30 skilled marksmen in the shooting preparation stage under noisy disturbance, weak light, and normal conditions were recorded. Therefore, the differences in neural mechanisms in the shooter’s brain during shooting aiming in different disturbance conditions were explored using an analytical approach that employs functional connectivity and brain network analysis based on graph theory. The relationship between these brain network characteristics and shooting performance was also compared. The results showed that (1) the average connection strength in the beta frequency band and connection intensity in the left and right temporal lobes of the shooters under noise disturbance were significantly higher than those under the other two conditions, and their brain networks also showed a higher global and local efficiency. In addition, (2) the functional connection intensity in the occipital region of the beta band was higher than that in the normal condition in the weak-light condition. The information interaction in the left parietal region also increased continually during the shooting process. (3) Furthermore, the shooters’ eigenvector centrality in the temporal and occipital regions with limited sensory function in the two conditions was lower than those in the normal condition. These findings suggest that noise disturbance activates the arousal level of the shooter’s brain and enhances the information processing efficiency of the brain network; however, it increases the mental workload. In weak-light conditions, shooters focus more on visual information processing during aiming and strengthen the inhibition of functions in the brain regions unrelated to shooting behavior. Audiovisual disturbance renders the cortical regions equivalent to the audiovisual perception function in the shooter’s brain less important in the entire brain network than in the normal condition. Therefore, these findings reveal the effect of audiovisual disturbance on the functional network of the cortex in the shooting preparation stage and provide a theoretical basis for further understanding the neural mechanism of the shooting process under sensory disturbances

    Linear Quadratic Optimal Control with the Finite State for Suspension System

    No full text
    The control algorithm could greatly help the suspension system improve the comprehensive performance of the vehicle. Existing control methods need to obtain the intermediate states, which are difficult to obtain directly or accurately when estimated by filters or observers. Thus, this paper proposed a new practical finite state LQR control method to deal with this problem. By combining with the output state of the finite sensor of the vehicle suspension system and weakening the unknown state as the goal, an optimization model is established with the design variables as the LQR weight coefficients. Then, the direct relationship between the current control input and the finite sensor output is obtained, and the finite state LQR control is realized. Taking the quarter-car suspension model as an example, the corresponding noise is added considering sensor accuracy, and the control performance of the four control methods is studied considering the uncertainties of suspension system parameters. In addition, the acceleration of sprung mass and the dynamic travel coefficient of suspension have been separately calculated by methods of finite state LQR control, LQR control, and PID control. The results show that there is not much difference between them under shock excitation or random excitation. However, the finite state LQR control method has the best comprehensive control performance in that its dynamic tire load coefficient is better than other methods; it could take into account the suspension work stroke coefficient, dynamic tire load coefficient, and sprung mass’ acceleration of the vehicle suspension system at the same time. In order to realize the optimal control effect with limited sensor arrangement, the finite state LQR control method only needs to obtain the current sensor output and the current control input, without estimating the unknown intermediate state. By this means, the proposed control method greatly simplifies the design of the control system and has great advantages on practical value

    Development of automatic arc sag measurement equipment for tensioned line tightening construction on overhead transmission lines

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    Abstract Due to the low degree of automation of the existing arc droop measurement device, the tension line digital twin system is not yet able to simulate the change of arc droop in the actual engineering situation in a high degree of real time. To this end, a kind of arc droop automatic measuring equipment applicable to the working condition of tension frame line tightening construction is developed. In terms of hardware, firstly, the STC microcontroller is used to control the motor to achieve free movement of the equipment on the wire. Secondly, the Beidou positioning module is used to collect the spatial coordinates of each point on the wire, thereby obtaining the spatial attitude of the wire and calculating the final sag. Finally, LoRa technology with long transmission distance and low power consumption is selected for wireless transmission of controlled data and collected data. The software system of the device is equipped with the motor's action logic, which cooperates with the hardware to respond to the control commands issued by the terminal. The developed arc droop measurement equipment has been successfully applied in the project, compared with the traditional arc droop observation construction method construction efficiency increased by 28%, the difference between the observation file arc droop and the design arc droop after erection of the line is 1.96%. Digital simulation and remote guidance of arc sag variations by the digital twin system for tension racking lines was realized while ensuring the engineering requirements

    A Review on Recent Progress Achieved in Boron Carbon Nitride Nanomaterials for Supercapacitor Applications

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    Supercapacitors are regarded as reliable energy storage devices to alleviate the energy crisis and environmental pollution. However, the relatively low capacitance and low energy density limit the practical application of supercapacitors. In this context, boron carbon nitride (BCN) nanomaterials have been extensively studied in the past decade due to their chemical and thermal stability, high mechanical strength, as well as tunable bandgap. The specific capacitance and energy density of supercapacitors can be significantly improved by fabricating nanostructured BCN-based electrode materials. In this review, the recent advances in the application of BCN-based materials in supercapacitors is presented. Strategies such as structure design, porosity/defect engineering, and hybrid nanostructure construction to boost the electrochemical performance of BCN-based materials are provided and, finally, promising research directions for novel energy storage materials are proposed

    Mildly Alkaline Preparation and Methylene Blue Adsorption Capacity of Hierarchical Flower-like Sodium Titanate

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    The hydrothermal preparation of flower-like layered sodium titanate architectures in a weakly alkaline medium is reported. NaCl was used as a morphology-directing agent, and a growth mechanism was proposed. The hierarchical structure is assembled from one-dimensional nanoribbons and exhibits an excellent removal capacity toward methylene blue (MB). A pseudo-second-order kinetic model was found to well describe the adsorption kinetics. Kinetic studies demonstrated that the overall rate of MB adsorption was controlled by surface adsorption and intraparticle diffusion. Results of this work are of great significance for environmental applications of flower-like layered sodium titanate architectures as a promising adsorbent material used for water purification

    Cost-Effective Asymmetric Supercapacitors Based on Nickel Cobalt Oxide Nanoarrays and Biowaste-Derived Porous Carbon Electrodes

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    Two nanostructured electrode materials are fabricated and used to construct cost-effective asymmetric supercapacitors (ASCs). Hierarchical nickel cobalt oxide nanoarrays (NCO-NA) consisting of nanosheets (NCO-NS) or nanowires (NCO-NW) are uniformly grown on Ni foam by a simple, effective, and generally applicable method, while biowaste-derived hierarchical porous carbon (Bio-HPC) with an interconnected microstructure is fabricated by pretreatment with potassium hydroxide and followed by direct pyrolysis. Considering the mass of NiCo<sub>2</sub>O<sub>4</sub>, the maximum specific capacitance of the hierarchical NCO-NS and NCO-NW electrodes are 2300 and 2333 F g<sup>–1</sup>, respectively, and the specific capacitance of the Bio-HPC electrode is 253.9 F g<sup>–1</sup> at a scan rate of 5 mV s<sup>–1</sup>. NCO-NA, Bio-HPC, a piece of polypropylene membrane, and 30 wt % KOH solution are assembled into a high-performance, low-cost ASC with the capability of rapidly storing electrical energy. The NCO-NW//Bio-HPC ASC exhibits a higher energy density compared with NCO-NS//Bio-HPC ASC, while the latter shows better cycling performance (the capacitance still remains 91.12% after 2000 cycles)

    Development of novel Gd-Fe/Ti composites with tunable thermal expansion property

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    Titanium alloys are considered one of the most promising materials. However, their poor thermal expansion property remains a major obstacle to their widespread application. In this study, we explored an innovative design strategy to tune the thermal expansion properties of titanium alloy. Specifically, we used rare earth iron intermetallic compounds (Gd-Fe IMCs) with low coefficient of thermal expansion (CTE) as expansion inhibitors to prepare composites with the required thermal expansion properties via in situ reaction. The morphology and size of Gd-Fe IMCs can be effectively controlled by electromagnetic and ultrasonic fields, resulting in a dense distribution of micro/nano-structured Gd-Fe IMCs and strong interfacial bonding of the composites. This alloy has an excellent CTE of 6.8 × 10 ^−6 /K and a high ultimate tensile strength of 921 MPa. The improvement in the physical properties (especially in thermal expansion properties) of titanium alloy can be attributed to the synergistic effect between Gd-Fe IMCs and Ti matrix. This design strategy can also be extended to other titanium alloys as a reference for designing low thermal expansion titanium alloys
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