Journal articles on the topic 'Longitudinal coupling strategy'
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1
Al-Budairi, Hassan, Patrick Harkness, and Margaret Lucas. "A Strategy for Delivering High Torsionality in Longitudinal-Torsional Ultrasonic Devices." Applied Mechanics and Materials 70 (August 2011): 339–44. http://dx.doi.org/10.4028/www.scientific.net/amm.70.339.
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A composite longitudinal-torsional vibration mode has applications in ultrasonic motors, ultrasonic welding and ultrasonic drilling. There are two ways to obtain this vibration behaviour using a single transducer, namely (i) coupling of a longitudinal and a torsional mode, which is known to be difficult; and (ii) degenerating a longitudinal mode to deliver longitudinal-torsional behaviour at the horn tip. A mode-degenerating horn is achieved by incorporating helical or diagonal slits in an otherwise traditional exponential horn driven by a Langevin transducer. However, it is often difficult with this configuration to avoid coupling of unwanted bending modes, low responsiveness, and loss of ultrasonic energy due to boundaries between tuned components. Therefore, in this study the mode-degenerating characteristics are achieved by incorporating the helical slits and exponential geometry features in the front mass of the transducer itself. Finite element analysis and vibration experimental analysis show that this strategy prevents coupling of bending modes, increases responsiveness, and reduces energy losses. Most importantly the transducer delivers a very high torsionality.
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Cheng, Shuo, Ming-ming Mei, Shi-yong Guo, Liang Li, Cong-zhi Liu, Xiang Chen, and Xiu-heng Wu. "A novel coupling strategy for automated vehicle’s longitudinal dynamic stability." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 10-11 (April 5, 2021): 2753–63. http://dx.doi.org/10.1177/09544070211006530.
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The autonomous vehicle has been developed widely, and attracted much attention of global automotive industry. Wherein, longitudinal dynamics control is one of the most crucial issues of autonomous vehicles. The throttle-by-wire (TBW) control could implement the acceleration command through adjusting the throttle opening, thus control the driving torque of the fuel autonomous vehicle. However, an automated vehicle controlled by traditional TBW in low-friction road conditions could reach large slip ratio region, which could adversely cause the loss of vehicle longitudinal dynamic stability. To tackle the mentioned issues, this paper proposes an adaptive sliding-mode control (SMC) algorithm to optimize tire slip speed of the automated vehicle. When the intervention conditions of active acceleration are satisfied, the TBW can take over the throttle opening control instead of the driver. Firstly, the SMC can calculate an intervention of the effective torque input based on tire torque balance dynamics. Moreover, a traction control system (TCS) and TBW coupling strategy based on the logic threshold method is put forward to response the optimum slip speed curve. Thus, during the vehicle starting process, a three-layer control strategy consisting of TBW, torque control, and pressure control of TCS is involved. Finally, real-car snow and ice road tests are carried out, and experimental results demonstrate great performance of the proposed strategy in complicated low-friction road.
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Chen, Zhi, Daobo Wang, Ziyang Zhen, Biao Wang, and Jian Fu. "Take-off and landing control for a coaxial ducted fan unmanned helicopter." Aircraft Engineering and Aerospace Technology 89, no. 6 (October 2, 2017): 764–76. http://dx.doi.org/10.1108/aeat-01-2016-0017.
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Purpose This paper aims to present a control strategy that eliminates the longitudinal and lateral drifting movements of the coaxial ducted fan unmanned helicopter (UH) during autonomous take-off and landing and reduce the coupling characteristics between channels of the coaxial UH for its special model structure. Design/methodology/approach Unidirectional auxiliary surfaces (UAS) for terminal sliding mode controller (TSMC) are designed for the flight control system of the coaxial UH, and a hierarchical flight control strategy is proposed to improve the decoupling ability of the coaxial UH. Findings It is demonstrated that the proposed height control strategy can solve the longitudinal and lateral movements during autonomous take-off and landing phase. The proposed hierarchical controller can decouple vertical and heading coupling problem which exists in coaxial UH. Furthermore, the confronted UAS-TSMC method can guarantee finite-time convergence and meet the quick flight trim requirements during take-off and landing. Research limitations/implications The designed flight control strategy has not implemented in real flight test yet, as all the tests are conducted in the numerical simulation and simulation with a hardware-in-the-loop (HIL) platform. Social implications The designed flight control strategy can solve the common problem of coupling characteristics between channels for coaxial UH, and it has important theoretical basis and reference value for engineering application; the control strategy can meet the demands of engineering practice. Originality/value In consideration of the TSMC approach, which can increase the convergence speed of the system state effectively, and the high level of response speed requirements to UH flight trim, the UAS-TSMC method is first applied to the coaxial ducted fan UH flight control. The proposed control strategy is implemented on the UH flight control system, and the HIL simulation clearly demonstrates that a much better performance could be achieved.
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Kim, Jinhee. "사업전략과 인사관리의 결합성이 기업성과에 미치는 효과에 대한 종단분석." Journal of the Korea Management Engineers Society 24, no. 1 (March 31, 2019): 55–72. http://dx.doi.org/10.35373/kmes.24.2.4.
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Bai, Yunlong, Gang Li, Hongyao Jin, and Ning Li. "Research on Lateral and Longitudinal Coordinated Control of Distributed Driven Driverless Formula Racing Car under High-Speed Tracking Conditions." Journal of Advanced Transportation 2022 (August 11, 2022): 1–15. http://dx.doi.org/10.1155/2022/7344044.
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Aiming at the problem that it is difficult to ensure the trajectory tracking accuracy and driving stability of the distributed driven driverless formula racing car under high-speed tracking conditions, a lateral and longitudinal coordinated control strategy is proposed. Based on the adaptive model predictive control theory, the lateral motion controller is designed, and the prediction time domain of the controller is changed in real time according to the change of vehicle speed. Based on the sliding mode variable structure control theory, a longitudinal motion controller is designed to accurately track the desired vehicle speed. Considering the coupling between the lateral and longitudinal controls, the lateral controller inputs the longitudinal speed and displacement of the vehicle, using the feedback mechanism to update the prediction model in real time, the longitudinal controller takes the front wheel angle as the input, the driving torque is redistributed through the differential drive control, and the lateral and longitudinal coordinated control is carried out to improve the trajectory tracking accuracy and driving stability. The typical working conditions are selected for co-simulation test verification. The results show that the lateral and longitudinal coordinated control strategy can effectively improve the vehicle trajectory tracking control accuracy and driving stability.
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Zhang, Sheng, and Xiangtao Zhuan. "Two-Dimensional Car-Following Control Strategy for Electric Vehicle Based on MPC and DQN." Symmetry 14, no. 8 (August 17, 2022): 1718. http://dx.doi.org/10.3390/sym14081718.
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For the coupling problem of longitudinal control and lateral control of vehicles, a two-dimensional (2-D) car-following control strategy for an electric vehicle is proposed in this paper. First, a 2-D car-following model for longitudinal following and lateral lane keeping is established. Then, a 2-D car-following control strategy is designed, and the longitudinal following control and lateral lane keeping control are integrated into one model predictive control (MPC) framework. The 2-D car-following strategy can realize the multi-objective coordinated optimization for longitudinal control and lateral control during the 2-D car-following process, and the multiple objectives are: safety, tracking, comfort, lane keeping, lateral stability and economy. In addition, the economy is important for electric vehicles. The weight matrix of the objective function in the MPC framework is symmetric, and the weight coefficients for the weight matrix have a great influence on the control. The contribution of this paper is: in order to adapt to different dynamic processes of lane keeping, the weight coefficients in the MPC framework are optimized in real-time based on the deep Q network (DQN) algorithm. Finally, to verify the 2-D car-following control strategy, a comparison strategy and two experimental scenarios are set, and simulation experiments are carried out. In scenario 1, compared with the comparison strategy, the lane keeping, lateral stability and economy of the proposed strategy are improved by 37.21%, 17.57% and 9.26%, respectively. In scenario 2, compared with the comparison strategy, the lane keeping, lateral stability and economy of the proposed strategy are improved by 36.45%, 16.66% and 18.52%, respectively. Therefore, compared with the comparison strategy, the 2-D car-following control strategy can have better lane keeping, lateral stability and economy on the premise of ensuring other performances during the 2-D car-following process.
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Wang, B., J. F. Guo, L. Yi, and W. H. Zhou. "Anti-impact tension control strategy for the space-tethered combination after target capture." Aeronautical Journal 122, no. 1257 (November 2018): 1775–87. http://dx.doi.org/10.1017/aer.2018.98.
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ABSTRACTAn electromechanical coupling model is established for the space-tethered combination (STC) under microgravity environment after target capture by the tethered robot system (TRS). A linearized dynamic model of the STC is put forward with its controllability and observability as a control system analyzed. A double closed-loop tension control strategy is proposed to mitigate the impact and suing longitudinal vibration caused by the velocity difference between the platform and target. Experiment setup is built on a ground-based flotation platform to investigate the impact of the STC. Results of simulation and experimental validation show that the proposed tension control strategy is responsive and rapid in tension tracking and effectively prevent impact.
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Ling, Hongwei, and Bin Huang. "Research on Torque Distribution of Four-Wheel Independent Drive Off-Road Vehicle Based on PRLS Road Slope Estimation." Mathematical Problems in Engineering 2021 (September 11, 2021): 1–11. http://dx.doi.org/10.1155/2021/5399588.
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In view of the high difficulty in coupling of various electric vehicle parameters, intractable parameter estimation, and unreasonable distribution of vehicle driving torque, the four-wheel hub motor is applied to drive electric vehicles, which can instantly obtain the torque and speed of the hub motor and achieve precise control of the torque of each wheel. According to the vehicle longitudinal dynamics model, a progressive RLS (PRLS) algorithm for real-time estimation of vehicle mass and road gradient is proposed. Meanwhile, by means of taking the longitudinal acceleration of the vehicle and the road gradient obtained from the estimation algorithm as the parameter of the torque distribution at the front and rear axles, a dynamic compensation and distribution control strategy of the front and rear axle torques is designed. Moreover, based on hardware-in-the-loop real-time simulation and real-vehicle tests, the effectiveness of the proposed estimation algorithm and the rationality of the real-time distribution control strategy of driving torque are verified.
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Wang, Jianfeng, Weihua Li, Jun Li, Yiqun Liu, Baoyu Song, and Haibo Gao. "Modeling a Driver’s Directional and Longitudinal Speed Control Based on Racing Track Features." Shock and Vibration 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/7487295.
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This study firstly analyses the driver’s manipulation behaviour and relates the different components of the driver model. Then, a model controlling the driver directions is built according to the prediction-follower theory with the aim of improving the point search algorithm. A model of the driving system of an electric vehicle is used to establish the longitudinal speed control model of the driver by using a feedforward-PID feedback control strategy. Our approach is to release the coupling between direction and speed control and build an integrated model that includes the direction and speed for an arbitrary path. Finally, the characteristics of an actual racing track are considered to establish the fastest driver control model. We simulated the typical operating conditions of our driver operation model. The simulation confirmed the effectiveness of the improved predictive point search algorithm and the integrated driver model to control the direction and speed for an arbitrary path.
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Olivieri, Carlo, Francesco de Paulis, Antonio Orlandi, Giorgio Giannuzzi, Roberto Salvati, Roberto Zaottini, Carlo Morandini, and Lorenzo Mocarelli. "Remote Monitoring of Joints Status on In-Service High-Voltage Overhead Lines." Energies 12, no. 6 (March 14, 2019): 1004. http://dx.doi.org/10.3390/en12061004.
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This work presents the feasibility study of an on-line monitoring technique aimed to discover unwanted variations of longitudinal impedance along the line (also named “impedance discontinuities”) and, possibly, incipient faults typically occurring on high voltage power transmission lines, like those generated by oxidated midspan joints or bolted joints usually present on such lines. In this paper, the focus is placed on the application and proper customization of a technique based on the time-domain reflectometry (TDR) technique when applied to an in-service high-voltage overhead line. An extensive set of numerical simulations are provided in order to highlight the critical points of this particular application scenario, especially those that concern the modeling of both the TDR signal injection strategy and the required high-voltage coupling devices, and to plan a measurement activity. The modeling and simulation approach followed for the study of either the overhead line or the on-line TDR system is fully detailed, discussing three main strategies. Furthermore, some measurement data that were used to characterize the specific coupling device selected for this application at high frequency—that is, a capacitive voltage transformer (CVT)—are presented and discussed too. This work sets the basic concepts underlying the implementation of an on-line remote monitoring system based on reflectometric principles for in-service lines, showing how much impact is introduced by the high-voltage coupling strategy on the amplitude of the detected reflected voltage waves (also named “voltage echoes”).
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Hong, Da, and Jihong Zhu. "Dynamic modeling and control method of a new concept wing-disk aircraft." MATEC Web of Conferences 189 (2018): 03015. http://dx.doi.org/10.1051/matecconf/201818903015.
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The research aimed at a new layout wing-disk solar aircraft concept with several wings around the disc fuselage, select coordinates and variables adaptively for the new dynamic subject, and establish dynamic model, using blade element momentum theory and CFD value for correction. Design the flight control strategy and controller constraint relations, put forward the method of control allocation and manipulation, and use nonlinear dynamic inversion control method aimed at the transverse and longitudinal coupling, serious nonlinear characteristics, and adds integral element as a robust dynamic inverse control to deal with the poor performance of previous method, and simulate to validate the control design.
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Yuan, Ye, Douglas Thomson, and Renliang Chen. "Propeller control strategy for coaxial compound helicopters." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 10 (October 26, 2018): 3775–89. http://dx.doi.org/10.1177/0954410018806796.
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The coaxial compound configuration has been proposed as a concept for future high-performance rotorcraft. The co-axial rotor system does not require an anti-torque device, and a propeller provides axial thrust. A well-designed control strategy for the propeller is necessary to improve the performance and the flight dynamics characteristics. A flight dynamics model of coaxial compound helicopter is developed to analyze these influences. The performance and the flight dynamics characteristics in different propeller strategies were first investigated. The results show that there is an improvement in the performance in high-speed flight when the propeller provides more propulsive forces. It also illustrates that a reasonable allocation of the rotor and the propeller in providing thrust can further reduce the power consumption in the mid speed range. In other words, the propeller control strategy can be an effective method to improve the cruise-efficiency. The flight dynamics analysis in this paper includes trim and handling qualities. The trim results prove that the propeller strategy can affect the collective pitch, longitudinal cyclic pitch, and the pitch attitude. If the control strategy is designed only to decrease the required power, it will result in a discontinuity in the trim characteristics. Handling qualities are investigated based on the ADS-33E-PRF requirement. The result demonstrates that the bandwidth and phase delay results and eigenvalue results in various speed at different propeller strategies are all satisfied. However, some propeller control strategies lead to severe inter-axis coupling in high-speed flight. Based on these results, this paper proposes the propeller control strategy for the coaxial compound helicopter. This strategy ensures good trim characteristics and handling qualities, which satisfy the related requirements, and improves the flight range or the performance in high-speed flight.
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Kasnakoğlu, Coşku. "Scheduled smooth MIMO robust control of aircraft verified through blade element SIL testing." Transactions of the Institute of Measurement and Control 40, no. 2 (August 25, 2016): 528–41. http://dx.doi.org/10.1177/0142331216661760.
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This paper demonstrates a multi-input multi-output (MIMO) robust control approach where multiple scheduled designs are merged to produce a smooth control law. The design is verified using software-in-the-loop (SIL) testing based on blade element theory (BET) for highly realistic flight simulations. An inner-loop attitude controller balances performance and robustness, achieving a fast response time, low overshoot, good noise rejection and minimal lateral–longitudinal coupling. The controllers are formed at several predetermined grid points so the design covers a wide flight envelope. Blade element SIL testing shows that the flight control system preserves stable flight and follows the references well, even under tough weather conditions. The proposed strategy is also compared with a classical autopilot design procedure and is seen to be superior.
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Zhang, Peisen, Jing Li, Weimin Zhang, Yang Hao, Gastone Ciuti, Tatsuo Arai, Paolo Dario, and Qiang Huang. "Endoluminal Motion Recognition of a Magnetically-Guided Capsule Endoscope Based on Capsule-Tissue Interaction Force." Sensors 21, no. 7 (March 30, 2021): 2395. http://dx.doi.org/10.3390/s21072395.
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A magnetically-guided capsule endoscope, embedding flexible force sensors, is designed to measure the capsule-tissue interaction force. The flexible force sensor is composed of eight force-sensitive elements surrounding the internal permanent magnet (IPM). The control of interaction force acting on the intestinal wall can reduce patient’s discomfort and maintain the magnetic coupling between the external permanent magnet (EPM) and the IPM during capsule navigation. A flexible force sensor can achieve this control. In particular, by analyzing the signals of the force sensitive elements, we propose a method to recognize the status of the motion of the magnetic capsule, and provide corresponding formulas to evaluate whether the magnetic capsule follows the motion of the external driving magnet. Accuracy of the motion recognition in Ex Vivo tests reached 94% when the EPM was translated along the longitudinal axis. In addition, a method is proposed to realign the EPM and the IPM before the loss of their magnetic coupling. Its translational error, rotational error, and runtime are 7.04 ± 0.71 mm, 3.13 ± 0.47∘, and 11.4 ± 0.39 s, respectively. Finally, a control strategy is proposed to prevent the magnetic capsule endoscope from losing control during the magnetically-guided capsule colonoscopy.
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Lin, Shirong, Zhongquan Nie, Weichao Yan, Yao Liang, Han Lin, Qing Zhao, and Baohua Jia. "All-optical vectorial control of multistate magnetization through anisotropy-mediated spin-orbit coupling." Nanophotonics 8, no. 12 (September 26, 2019): 2177–88. http://dx.doi.org/10.1515/nanoph-2019-0198.
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AbstractThe interplay between light and magnetism is considered as a promising solution to fully steer multidimensional magnetic oscillations/vectors, facilitating the development of all-optical multilevel recording/memory technologies. To date, impressive progress in multistate magnetization instead of a binary level has been witnessed by primarily resorting to double laser beam excitation. Yet, the control mechanisms are limited to specific magnetic medium or intricate optical configuration as well as overlooking the crystallographic architecture of the media and the polarization-phase linkage of the light fields. Here, we theoretically present a novel all-optical strategy for generating arbitrary multistate magnetization through the inverse Faraday effect. This is achieved by strongly focusing a single vortex-phase configured beam with circular polarization onto the anisotropic magnetic medium. By judiciously tuning the topological charge effect, the optical anisotropic effect, and the anisotropic optomagnetic effect, the light-induced magnetic vector can be flexibly redistributed between its transverse and longitudinal components, thus enabling orientation-unlimited multilevel magnetization control. In this optomagnetic process, we also reveal the role of anisotropy-mediated spin-orbit coupling, another physical mechanism that enables the effective translation of the angular momentum of light fields to the magnetic system. Furthermore, the conceptual paradigm of all-optical multistate magnetization is verified. Our findings show great prospect in multidimensional high-density optomagnetic recording and memory devices and also in high-speed information processing science and technology.
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Robert, D., R. N. Miles, and R. R. Hoy. "Tympanal hearing in the sarcophagid parasitoid fly Emblemasoma sp.: the biomechanics of directional hearing." Journal of Experimental Biology 202, no. 14 (July 15, 1999): 1865–76. http://dx.doi.org/10.1242/jeb.202.14.1865.
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In Diptera, tympanal hearing has evolved at least twice in flies that belong to two different families, the tachinids and the sarcophagids. Common to these flies is their parasitoid reproductive strategy, both relying on the acoustic detection and localization of their hosts, singing insects, by means of tympanal hearing organs. In the present study, the external anatomy of the unusual hearing organs of the sarcophagid fly Emblemasoma sp. is described. The sarcophagid ears bear numerous anatomical similarities with those of ormiine tachinids: they are located on the ventral prosternum and possess a pair of scolopidial mechanoreceptive sense organs. A striking difference, however, resides in the lack of a well-defined presternum in the sarcophagid tympanal system. Instead, a deep longitudinal fold, the tympanal fold, spans both hemilateral tympanal membranes across the midline of the animal. Measured using laser Doppler vibrometry, the tympanal mechanical response in the sound field reveals asymmetrical deflection shapes that differ from those of tachinids. Lacking a central fulcrum, the sarcophagid tympanal complex presents different vibrational modes that also result in interaural coupling. The evolutionarily convergent, yet distinct, solutions used by these two small auditory systems to extract directional cues from the sound field and the role of tympanal coupling in this process are discussed.
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Ma, Yalina, Qian Sheng, Guimin Zhang, and Zhen Cui. "A 3D Discrete-Continuum Coupling Approach for Investigating the Deformation and Failure Mechanism of Tunnels across an Active Fault: A Case Study of Xianglushan Tunnel." Applied Sciences 9, no. 11 (June 5, 2019): 2318. http://dx.doi.org/10.3390/app9112318.
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For water transmission tunnels constructed in high-risk seismic regions of western China, active faults pose threats of serious ruptures to the tunnels. To overcome this issue, a 3D discrete-continuum coupling approach is introduced into the study. By this approach, spherical discrete-element-method (DEM) particles are used to represent the surrounding rock mass, and the tunnel is considered to be the continuous finite-difference-method (FDM) zone. In this way, a 3D coupling model was established to study the longitudinal displacement profile and stress response of the tunnel lining under various fault dislocations. The failure pattern of the surrounding rock mass was investigated from a micro perspective. Meanwhile, the design strategy of flexible joint was investigated with the present numerical model. The results from a parametric study show that the smaller segment length, wider width and weaker strength of the flexible joints are beneficial to the anti-dislocation performance of the tunnel. Moreover, an orthogonal array test technique was utilized to investigate the influence level of the main design parameters of the flexible joint on the lining internal stress. With the obtained knowledge, the optimal combination for flexible joint design was presented. Findings may provide references for the anti-dislocation issue of tunnels across active faults.
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Zhou, Pan, Renliang Chen, and Zhiming Yu. "Analysis on controllability and stability of quad-tilt-rotor aircraft in helicopter mode." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 39, no. 3 (June 2021): 675–84. http://dx.doi.org/10.1051/jnwpu/20213930675.
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The controllability and stability of quad-tilt-rotor aircraft in helicopter mode are modeled and analyzed, which will provide a theoretical guidance for the subsequent control system design. First of all, the flight dynamics model is established considering rotor-wing interference and verified with relevant experiments. Then, a control strategy for helicopter mode is proposed with trim characteristic analysis. Finally, corresponding control efficiency and cross coupling are calculated and analyzed along with characteristics of the stability derivatives and eigenvalues. The results show that the value of heading control efficiency is much smaller than that of other channels. The longitudinal force and pitch moment caused by vertical control input increase with the increase of the velocity. Yawing moment caused by lateral control input shows similar variations. The velocity stability becomes worse with the increase of the velocity. The stability of all other modes is augmented as velocity increases except the spiral mode.
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Louf, J. F., G. Guéna, E. Badel, and Y. Forterre. "Universal poroelastic mechanism for hydraulic signals in biomimetic and natural branches." Proceedings of the National Academy of Sciences 114, no. 42 (October 2, 2017): 11034–39. http://dx.doi.org/10.1073/pnas.1707675114.
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Plants constantly undergo external mechanical loads such as wind or touch and respond to these stimuli by acclimating their growth processes. A fascinating feature of this mechanical-induced growth response is that it can occur rapidly and at long distance from the initial site of stimulation, suggesting the existence of a fast signal that propagates across the whole plant. The nature and origin of the signal is still not understood, but it has been recently suggested that it could be purely mechanical and originate from the coupling between the local deformation of the tissues (bending) and the water pressure in the plant vascular system. Here, we address the physical origin of this hydromechanical coupling using a biomimetic strategy. We designed soft artificial branches perforated with longitudinal liquid-filled channels that mimic the basic features of natural stems and branches. In response to bending, a strong overpressure is generated in the channels that varies quadratically with the bending curvature. A model based on a mechanism analogous to the ovalization of hollow tubes enables us to predict quantitatively this nonlinear poroelastic response and identify the key physical parameters that control the generation of the pressure pulse. Further experiments conducted on natural tree branches reveal the same phenomenology. Once rescaled by the model prediction, both the biomimetic and natural branches fall on the same master curve, enlightening the universality of our poroelastic mechanism for the generation of hydraulic signals in plants.
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Zhu, Jianxu, Shupei Zhang, Guolin Wang, Wei Zhang, and Sheng Zhang. "Research on vehicle stability region under critical driving situations with static bifurcation theory." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 8 (February 23, 2021): 2072–85. http://dx.doi.org/10.1177/0954407021993941.
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A strategy for solving the static bifurcation points of the 5DOF vehicle nonlinear system is proposed to research the stability region of the system. The bifurcation characteristics of the system is changed by the coupling of the steering and the engine braking torques under the high-speed emergency steering conditions, and the corresponding vehicle stability region must be redefined. The stability region of the vehicle which is influenced by the engine braking torque is determined with the static bifurcation theory, and the equilibrium points of the 5DOF vehicle system are solved with the phase space method and the random weight particle swarm optimization (RWPSO) algorithm. The vehicle stability is verified with different initial longitudinal speeds and different steering angles, and the simulation results validate the effectiveness of the stability region under the critical driving conditions. The study is conducive to the development of the active safety control systems and the application of nonlinear system dynamics in the automotive field. Furthermore, it provides the theoretical support for the application of the vehicle-handling stability.
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Houari, Aoued, Imine Bachir, Della Krachai Mohame, and Mohamed Kara Mohamed. "PID vs LQR controller for tilt rotor airplane." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 6 (December 1, 2020): 6309. http://dx.doi.org/10.11591/ijece.v10i6.pp6309-6318.
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The main thematic of this paper is controlling the main manoeuvers of a tilt rotor UAV airplane in several modes such as vertical takeoff and landing, longitudinal translation and the most important phase which deal with the transition from the helicopter mode to the airplane mode and visversa based on a new actuators combination technique for specially the yaw motion with not referring to rotor speed control strategy which is used in controlling the attitude of a huge number of vehicles nowadays. This new actuator combination is inspired from that the transient response of a trirotor using tilting motion dynamics provides a faster response than using rotor speed dynamics. In the literature, a lot of control technics are used for stabilizing and guarantee the necessary manoeuvers for executing such task, a multiple Attitude and Altitude PID controllers were chosen for a simple linear model of our tilt rotor airplane in order to fulfill the desired trajectory, for reasons of complexity of our model the multiple PID controller doesnt take into consideration all the coupling that exists between the degrees of freedom in our model, so an LQR controller is adopted for more feasible solution of complex manoeuvering, the both controllers need linearization of the model for an easy implementation.
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Wu, Bo, Xiaohai Xu, Shigang Luo, Dedao Yan, Kai Song, Xiang Zhang, and Fang He. "Study on the Mechanical Properties and Strengthening Mechanism of Interface-Modified Carbon Fiber Mesh Reinforced Cement-Based Composites with SCA&HMC." Molecules 24, no. 21 (November 5, 2019): 3989. http://dx.doi.org/10.3390/molecules24213989.
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Carbon fiber mesh reinforced cement-based composites (CMCCs) have received extensive attention in the field of engineering repair and structural reinforcement due to their outstanding properties such as two-way force, rust prevention, high specific strength, and low base surface requirements. However, the development of this material has been slowed down to some extent due to the poor interfacial bonding between the carbon fiber mesh and the cement matrix. In this paper, a novel fabrication strategy was proposed in which the carbon fiber mesh was modified with epoxy resin and silane coupling agent (SCA) to increase its surface chemical activity. Meanwhile, the hydroxymethyl cellulose (HMC) was also filled into the concrete matrix to improve the mechanical strength of the matrix as well as the load transfer behaviors between the mortar and carbon fiber (CF) mesh. The potential to employ SCA and HMC was evaluated for the making of CMCCs via the above methods. The results showed that the longitudinal shear strength of composites with SCA and SCA&HMC increased by 26.6% and 56.1% compared to those of CF with epoxy resin (EP) reinforced composites, respectively. The flexural strength of composite with SCA&HMC increases by 147.6% compared to I-(F) without CF. The novel II-HCM&CF/EP-SCA composites with excellent performance are promised to be applied in practical uses.
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Zhou, Qiaojun, Xudong Xia, Jian Wang, Yun Zhou, and Jianneng Chen. "Design and Experiment of the Automatic Laying System for Rice Seedling Tray." Agriculture 11, no. 7 (July 19, 2021): 679. http://dx.doi.org/10.3390/agriculture11070679.
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In the process of raising rice seedlings, it is necessary to manually place the seedling trays one by one in the seedling field, which is labor intensive and low in efficiency. In order to solve this problem, according to the actual conditions of the rice seedling field, this paper designs and develops an automatic rice tray laying system, which consists of a gantry truss moving unit, a tray laying trolley unit, a tray laying mechanism unit and a sensor control unit. Through the movement and timing coordination of the cams in the laying mechanism unit, four actions of holding, clamping, laying and restoring are designed to realize the orderly and automatic laying of the stacked seedling trays one by one. In order to meet the agronomic requirements of the horizontal and vertical spacing of seeding trays, especially the efficiency of rice tray laying, the control strategies of the key parts of the system were simulated, selected and optimized. For the longitudinal movement of the gantry truss, the cross-coupling control strategy is adopted to realize the detection and compensation correction of the synchronous position error of the two driving motors. As for the drive motor of the laying trolley and the laying mechanism, the optimized master-slave follow-up control method is adopted to improve the efficiency and accuracy. The results of simulation and field experiment show that when the tray trolley moves on the gantry truss at the speed of 7.5 cm/s, the gantry truss moves at the speed of 35 cm/s in the longitudinal direction, and when the height of the tray laying mechanism is 100 mm from the ground and the motor speed is 375 rpm, the horizontal spacing of the tray can be maintained at 25 ± 5 mm and the vertical spacing at 15 ± 5 mm. The efficiency of tray laying can be increased by 35.7%, up to 380 trays/h, meeting the technical requirements of mechanized field tray laying.
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Przewłocka-Kosmala, Monika, Ewelina Jasic-Szpak, Aleksandra Rojek, Maciej Kabaj, James E. Sharman, and Wojciech Kosmala. "Association of central blood pressure with left atrial structural and functional abnormalities in hypertensive patients: Implications for atrial fibrillation prevention." European Journal of Preventive Cardiology 26, no. 10 (March 26, 2019): 1018–27. http://dx.doi.org/10.1177/2047487319839162.
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AimsFunctional and structural abnormalities of the left atrium have been demonstrated to be clinically and prognostically significant in a range of cardiovascular disorders, increasing the risk of atrial fibrillation. Among the potential contributors to these aberrations, central arterial factors remain insufficiently defined. Accordingly, we sought to investigate the determinants of left atrium abnormalities in hypertension, with special focus on central haemodynamics.MethodsIn this retrospective, cross-sectional study, 263 patients (age 63.8 ± 8.0 years) with uncomplicated hypertension underwent echocardiography including left atrium strain (LAS) and volume analysis, and central haemodynamics assessment using radial tonometry.ResultsPatients were grouped depending on LAS and left atrium volume index (LAVI), using externally validated cutpoints (34.1% for LAS and 34 ml/m2for LAVI). The subset with lower LAS ( n = 124) demonstrated higher central (cPP) and brachial pulse pressure (bPP), ventricular- arterial coupling, left ventricular mass index (LVMI) and LAVI, and lower global left ventricular longitudinal strain and early diastolic tissue velocity (e′). Patients with higher LAVI ( n = 119) presented higher systolic blood pressure, cPP, bPP, central augmentation pressure, LVMI and E/e′ ratio and lower LAS. In multivariable analysis, cPP was independently associated with both LAS ( β = –0.22; p = 0.002) and LAVI ( β = 0.21; p = 0.003). No independent associations with left atrium parameters were shown for bPP.ConclusionHigher cPP is detrimentally associated with left atrium structural and functional characteristics, thus providing a possible pathophysiological link with the development of substrate for atrial fibrillation. Prophylaxis of atrial fibrillation might be another argument for consideration in the treatment strategy in hypertension targeted measures addressing central blood pressure.
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Zhang, Ting, and Hongguang Li. "Adaptive modal vibration control for smart flexible beam with two piezoelectric actuators by multivariable self-tuning control." Journal of Vibration and Control 26, no. 7-8 (January 6, 2020): 490–504. http://dx.doi.org/10.1177/1077546319889842.
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It has been popular for decades that the vibrations of space structures are suppressed with smart actuators. However, the higher mode vibrations are often motivated when a control strategy is applied to attenuate the vibration for the smart structures. Moreover, if the multi-mode vibration of a smart structure is suppressed with multi-actuators, a proper multivariable control law will be adopted to solve the coupling problem caused by the multi-actuators of the smart structure. Therefore, in the paper, a decoupling technique for two modal vibrations of a smart flexible beam with two piezoelectric patches is adopted by adaptive control. The proposed control law is designed with a multivariable minimum variance self-tuning control. Considering the first two orders of modal vibrations, two piezoelectric patches are configured on the flexible beam according to the strain of the first two orders of modal vibrations along the longitudinal direction of the beam. A dynamical model for the flexible beam with two piezoelectric actuators is constructed by the mode superposition method. With the dynamical model, simulations are implemented to suppress the free vibration of the flexible beam. Moreover, experiments are carried out to verify the effectiveness of the multivariable minimum variance self-tuning control for vibration suppression of the flexible structure. The control results clearly show that the free vibration amplitude of the cantilevered beam with two control voltages applied to the two piezoelectric patches is less than that with one control voltage applied to the first piezoelectric actuator. Thus, multivariable minimum variance self-tuning control is a more efficient approach for suppressing multimodal vibration for a smart flexible beam with two piezoelectric actuators compared with the conventional velocity feedback control.
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Carpenter, Chris. "Tubing Failure in HP/HT Wells Investigated and Mitigated." Journal of Petroleum Technology 73, no. 03 (March 1, 2021): 56–57. http://dx.doi.org/10.2118/0321-0056-jpt.
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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 20136, “Research and Application of Fracture Failure Control Technology for 13Cr Tubing in HP/HT Gas Wells,” by Lei Ma, Hongtao Liu, and Hailong Geng, PetroChina, et al., prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13-15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission. Super 13Cr-110 tubing used in high-pressure, high-temperature (HP/HT) gas wells in the Tarim oil field has experienced numerous failures. After a series of investigations for root-cause analysis, the conclusion was that fracture of the tubing mechanistically is categorized as stress corrosion cracking (SCC) and is closely related to the application of phosphate-based completion fluid. Further tests indicated that Super 13Cr (S13Cr) tubing specimens experienced SCC with phosphate-based completion fluids contaminated with mud and oxygen, whereas formate-based completion fluid is compatible with S13Cr tubing. At present, 55 HP/HT gas wells in the field have used formate-based completion fluid with no tubing string fracture. Introduction Compared with the Gulf of Mexico, the North Sea, the South China Sea, the Qiongqiong Basin, and various Chinese oil and gas fields, the oil pipelines in the Tarim field are among the most difficult with regard to service conditions, which are characterized by extreme operating conditions such as high pump pressure and large displacement reform. Construction and high-yield alternating loads on tubing string and joint and a harsh, corrosive environment [chloride content greater than 80 000 mg/L, carbon dioxide (CO2) partial pressure greater than 1 MPa, and the presence of fresh and residual acid] pose significant challenges to the safe service of the tubing string. In the early stages of production, S13Cr oil pipe was selected as the completion string of the HP/HT gas well in the Kuqa mountain front, but in recent years, the S13Cr-110 pipe of the HP/HT gas well in the Tarim field has been continuously fractured. Failure accidents have caused serious economic losses. In the complete paper, through lateral comparison analysis of the failed tubing and indoor simulation experiments, the cause of the tubing fracture is discovered, solution measures are initiated, and good application results are achieved. Comparative Analysis of Oil-Pipe Failures Comparative Analysis of Fracture Macroscopic Morphology. When comparing the macroscopic topographic maps of oil-pipe failures seen in six studied wells, fracture locations of three wells are located in the coupling, while fracture locations of the other three wells are located on the body. In five wells (Wells A through E), the tubing fracture is neat, indicating brittle fracture with no plastic deformation. Well F, however, has a visible longitudinal crack on the surface of the tubing, and many burrs are visible at the fracture. Comparison and Analysis of Working Conditions of Failed Tubing. Through comparative analysis, it was determined that five of the six wells have under-gone acidification. The service shaft temperature, pressure, CO2 content, and formation water salinity of the failed wells differ, but, in five of the six wells, the tubing was exposed to a phosphate-based completion fluid.
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Potier, Luc, Florent Duchaine, Bénédicte Cuenot, Didier Saucereau, and Julien Pichillou. "Prediction of Wall Heat Fluxes in a Rocket Engine with Conjugate Heat Transfer Based on Large-Eddy Simulation." Entropy 24, no. 2 (February 9, 2022): 256. http://dx.doi.org/10.3390/e24020256.
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Although a lot of research and development has been done to understand and master the major physics involved in cryogenic rocket engines (combustion, feeding systems, heat transfer, stability, efficiency, etc.), the injection system and wall heat transfer remain critical issues due to complex physics, leading to atomization in the subcritical regime and the interactions of hot gases with walls. In such regimes, the fuel is usually injected through a coaxial annulus and triggers the atomization of the central liquid oxidizer jet. This type of injector is often referred to as air-assisted, or coaxial shear, injector, and has been extensively studied experimentally. Including such injection in numerical simulations requires specific models as simulating the atomization process is still out of reach in practical industrial systems. The effect of the injection model on the flame stabilization process and thus on wall heat fluxes is of critical importance when it comes to the design of wall-cooling systems. Indeed, maximizing the heat flux extracted from the chamber can lead to serious gain for the cooling and feeding systems for expander-type feeding cycles where the thermal energy absorbed by the coolant is converted into kinetic energy to drive the turbo-pumps of the feeding system. The methodology proposed in this work to numerically predict the flame topology and associated heat fluxes is based on state-of-the-art methods for turbulent reactive flow field predictions for rocket engines, including liquid injection, combustion model, and wall treatment. For this purpose, high-fidelity Large Eddy Simulation Conjugate Heat Transfer, along with a reduced kinetic mechanism for the prediction of H2/O2 chemistry, liquid injection model LOx sprays, and the use of a specific wall modeling to correctly predict heat flux for large temperature ratio between the bulk flow and the chamber walls, is used. A smooth and a longitudinally ribbed combustor configuration from JAXA are simulated. The coupling strategy ensures a rapid convergence for a limited additional cost compared to a fluid-only simulation, and the wall heat fluxes display a healthy trend compared to the experimental measurements. An increase of heat transfer coherent with the literature is observed when walls are equipped with ribs, compared to smooth walls. The heat transfer enhancement of the ribbed configuration with respect to the smooth walls is coherent with results from the literature, with an increase of around +80% of wall heat flux extracted for the same chamber diameter.
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Zhang, Ziyu, Chunyan Wang, Wanzhong Zhao, and Jian Feng. "Longitudinal and lateral collision avoidance control strategy for intelligent vehicles." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, June 4, 2021, 095440702110240. http://dx.doi.org/10.1177/09544070211024048.
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In order to solve the problems of longitudinal and lateral control coupling, low accuracy and poor real-time of existing control strategy in the process of active collision avoidance, a longitudinal and lateral collision avoidance control strategy of intelligent vehicle based on model predictive control is proposed in this paper. Firstly, the vehicle nonlinear coupling dynamics model is established. Secondly, considering the accuracy and real-time requirements of intelligent vehicle motion control in pedestrian crossing scene, and combining the advantages of centralized control and decentralized control, an integrated unidirectional decoupling compensation motion control strategy is proposed. The proposed strategy uses two pairs of unidirectional decoupling compensation controllers to realize the mutual integration and decoupling in both longitudinal and lateral directions. Compared with centralized control, it simplifies the design of controller, retains the advantages of centralized control, and improves the real-time performance of control. Compared with the decentralized control, it considers the influence of longitudinal and lateral control, retains the advantages of decentralized control, and improves the control accuracy. Finally, the proposed control strategy is simulated and analyzed in six working conditions, and compared with the existing control strategy. The results show that the proposed control strategy is obviously better than the existing control strategy in terms of control accuracy and real-time performance, and can effectively improve vehicle safety and stability.
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Bosso, N., M. Magelli, L. Rossi Bartoli, and N. Zampieri. "The influence of resistant force equations and coupling system on long train dynamics simulations." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, March 16, 2021, 095440972110011. http://dx.doi.org/10.1177/09544097211001149.
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In the simulation of the longitudinal dynamics of long trains, the modeling of the resistant forces and of the coupling system are two essential aspects. The modeling of the resistant forces directly affects the speed reached by each vehicle as well as the in-train forces. A literature review witnesses different laws for the calculation of both ordinary and accidental resistances. One of the objectives of this paper is to evaluate from the numerical point of view the influence of the resistant forces modeling strategy on the simulation outputs, i.e., on the speeds and in-train forces, by comparing different laws for propulsion and curving resistances. For what concerns the connection between the vehicles of the train, it is well known that the connection system is of utmost importance for the safety and running stability of the train. In this paper, the two existing coupling systems, i.e., the European buffer-hook system and the coupler used outside the European continent are first described, both in terms of operation and modelling techniques, and then they are compared on the same simulation scenario. All the simulations are performed on the first scenario of the International benchmark of the longitudinal train dynamic simulators, using the LTDPoliTO code developed by the railway research team from Politecnico di Torino.
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Lu, Hangyu, Jianwei Lu, Heng Wei, Lei Shi, and Shenyong Ye. "On the non-linear dynamics of vehicle shimmy coupled with handling motions: modelling, bifurcation analysis, and validations." Journal of Vibration and Control, May 28, 2022, 107754632210962. http://dx.doi.org/10.1177/10775463221096258.
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A novel vehicle dynamic model considering the coupling mechanism between the front wheel shimmy and the vehicle lateral handling motions is established to investigate the interacting effect between the steering shimmy instability and the general motion instability, that focuses especially on the influence of the tyre force saturation induced by lateral-longitudinal coupling when different degrees and allocation strategy of braking force are applied. The typical 3-degree-of-freedom front wheel shimmy structure of dependent suspension is dynamically modelled by using the Lagrange method, alongside the equations for plane vehicle handling motions introduced. The stretched-string-based tyre kinematic equations, that describe the transient tyre-road contact status, are proposed by analytically deriving the coupling relations between the angular shimmy variables and vehicle motion status. A theoretically approximated linear tyre model, based on the coupling between vertical, longitudinal, and lateral directional forces, is analytically derived for stability analysis. Meanwhile, a complete PAC-2002 tyre model, with experimentally identified parameters, is employed for simulation verification. The stability chart of linear stability analysis shows the variation of the system bifurcation curves and stable parameter region under different parametric configurations, which gives that the degrees and allocations of braking force largely affect the stable parameter domain and the global stability. The variations of the system characteristic roots indicate that both Hopf and S-N bifurcation could happen due to shimmy oscillations and destabilization of motion, respectively, and their co-existence at certain parameter domains make the dynamic behaviour further unpredictable and complex. Numerical simulation verifies the dynamical characteristics of shimmy, and further analysis shows that three types of vehicle motion instability which coexisted with shimmy instability could be triggered by the coupling effect. In addition, the variation law of limit-cycle amplitude under varying vehicle driving inputs is summarized, and finally, a preliminary experiment is conducted for validations.
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Gilormini, Thomas, Pascal Chesse, Xavier Tauzia, and Hervé Colin. "Design and off-line tuning of a longitudinal driver model for EiL applications." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, August 30, 2021, 095440702110413. http://dx.doi.org/10.1177/09544070211041335.
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Tightnening emission regulations and increasing powertrain complexity lead car manufacturers to rely on novel testing methods in order to frontload development. Among these, Engine-in-the-Loop, that is, the coupling of a physical internal combustion engine (ICE) on a testbed with a virtual environment, shows great promise for emission- and consumption-related tasks. In particular, this study focuses on the driver model, a simple yet crucial component of the virtual environment. A longitudinal driver model is developed in Simulink based on the PI-regulation structure and augmented with anti-windup, cycle preview, and takeoff strategy. While the PI approach is generally chosen in the literature, this study details the implementation of the added functions, and proposes a method for the gains of the model to be tuned in simulation by considering engine dynamics, and using several performance indicators. The virtual driver is then tested in a complete EiL setup simulating an electric hybrid driveline and shows satisfactory cycle-following and overall behavior on a WLTC. Robustness of the tuning method is also studied by varying vehicle parameters on the EiL bench.
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Sacks, Dashiell D., Paul E. Schwenn, Larisa T. McLoughlin, Jim Lagopoulos, and Daniel F. Hermens. "Phase–Amplitude Coupling, Mental Health and Cognition: Implications for Adolescence." Frontiers in Human Neuroscience 15 (March 26, 2021). http://dx.doi.org/10.3389/fnhum.2021.622313.
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Identifying biomarkers of developing mental disorder is crucial to improving early identification and treatment—a key strategy for reducing the burden of mental disorders. Cross-frequency coupling between two different frequencies of neural oscillations is one such promising measure, believed to reflect synchronization between local and global networks in the brain. Specifically, in adults phase–amplitude coupling (PAC) has been shown to be involved in a range of cognitive processes, including working and long-term memory, attention, language, and fluid intelligence. Evidence suggests that increased PAC mediates both temporary and lasting improvements in working memory elicited by transcranial direct-current stimulation and reductions in depressive symptoms after transcranial magnetic stimulation. Moreover, research has shown that abnormal patterns of PAC are associated with depression and schizophrenia in adults. PAC is believed to be closely related to cortico-cortico white matter (WM) microstructure, which is well established in the literature as a structural mechanism underlying mental health. Some cognitive findings have been replicated in adolescents and abnormal patterns of PAC have also been linked to ADHD in young people. However, currently most research has focused on cross-sectional adult samples. Whereas initial hypotheses suggested that PAC was a state-based measure due to an early focus on cognitive, task-based research, current evidence suggests that PAC has both state-based and stable components. Future longitudinal research focusing on PAC throughout adolescent development could further our understanding of the relationship between mental health and cognition and facilitate the development of new methods for the identification and treatment of youth mental health.
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Gutiérrez, Eva, Irene Carrión, Carmen Olmos, Pilar Jiménez, Luis Nombela, Eduardo Pozo, Patricia Mahía, Sandra Gil, Alberto de Agustín, and Fabián Islas. "Cardiac Damage Staging in Patients Undergoing Transcatheter Aortic Valve Replacement: Incremental Value of Global Longitudinal Strain and Right Ventricular-Arterial Coupling." EMJ Cardiology, October 6, 2022, 27–28. http://dx.doi.org/10.33590/emjcardiol/10066961.
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Liu, Zhitao, Jianqing Li, Changsheng Gao, and Wuxing Jing. "Bifurcation analysis for a novel flight vehicle with pitch-control single moving mass." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, May 28, 2021, 095441002110232. http://dx.doi.org/10.1177/09544100211023259.
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Moving mass flight vehicle is a strongly nonlinear system under high speed flying conditions. The system attitude dynamics becomes even more complex due to the coupling between the internal moving mass with large mass ratio and the vehicle body. This article investigates the open-loop nonlinear dynamics of a novel flight vehicle with pitch-control single moving mass from the prospective of bifurcation theory and continuation methods. Of particular interest is the influence of moving mass parameters on the number of system equilibrium points, stability of equilibrium curves, bifurcation characteristics, and the longitudinal static stability. Numerical results reveal the bifurcation phenomena existing in the proposed flight vehicle; the generated bifurcation diagrams illustrate that the multiple sets of limit points and Hopf points divide the moving mass parameter space into different regions with different values and types of stability, thus indicating the significant role of the moving mass parameters in the system nonlinear dynamics. Finally, a design strategy for the moving mass parameters is concluded based on the bifurcation analysis results.
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Zhang, Wei, Hui Liu, Xun Zhang, Yunhao Wu, Pu Gao, Zhen Wang, and Wannian Zhang. "Torque ripple compensation control for hybrid UGVs in mode transition based on current harmonic control of a PMSM." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, December 6, 2020, 095440702097832. http://dx.doi.org/10.1177/0954407020978320.
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Load jumping and mode transitions both cause the unstable dynamic states for compound power-split hybrid Unmanned Ground Vehicles (UGVs), and these phenomena lead to vibrations of the transmission system and longitudinal buffeting of the vehicle. This study presents a feed-forward compensation control strategy for load jumping and mode transitions to reduce the corresponding torsional vibration in hybrid UGVs. The proposed method injects an appropriate harmonic current into a permanent magnet synchronous motor (PMSM) to generate a harmonic torque that is opposite to the load torque, which improves the dynamic response quality of the vehicle load. First, the multimode structure of a hybrid UGV and mode switching vibration and shock are investigated, as well as a feed-forward compensate control architecture is proposed. Second, two models are established the PMSM dynamic model based on the electromagnetic coupling principle and a 2-degree-of-freedom torsional vibration model of transmission system by simplifying the vehicle system. Third, the harmonic current injection method is proposed, and the harmonic current equation is derived. Based on the field-oriented control algorithm, a double closed-loop controller is designed for the torque and speed of the PMSM, and the internal model control method is applied to design the current controller. The simulation results show that the proposed strategy effectively suppresses jerk and that the harmonics current transfers the energy from the mechanical vibrations of the system into electric power fluctuations.
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Sang, Hutang, Jing Zeng, Feng Gan, Jian Mu, and Yayun Qi. "A study of wheel wear on a high-speed railway motor car." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, April 26, 2022, 095440972210964. http://dx.doi.org/10.1177/09544097221096467.
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Wheel/rail wear is one of the key issues in the safe operation of a high-speed railway motor car. This paper analyzes and predicts the wheel wear evolution of motor car during the long-term operation process. Firstly, the detailed motor car with gear transmission systems and trailer car of the high-speed train, which take into account various non-linear factors such as dampers, bump stops, wheel/rail contact relation, etc., are developed to obtain interaction force between wheel and rail. Secondly, according to the tread update strategy based on fixed travel distance, a novel wheel wear prediction model integrating the Archard wear model and previous dynamics system is established. In order to more accurately obtain the dynamic responses of the motor car, the comprehensive gear transmission system coupling with motor bogie is also built, which considers the time-varying mesh stiffness and gear shift coefficient. And the corresponding traction characteristic curve is also applied to the gear transmission system. Finally, the wheel wear evolution in one re-profiling cycle is simulated to verify the developed model, and the wheel wear mechanism is investigated in detail. Furthermore, the influence of traction velocity on wheel wear is also investigated. The simulation shows that the cumulative wear amount of both two cars increases gradually and the wear rate decreases gradually with traveling mileage, but the wear rate of the trailer car decreases faster than that of the motor car due to larger longitudinal creepage and longitudinal creep force induced by traction torque. Moreover, the max wheel wear depth and wear bandwidth for motor car gradually increase with traction velocity. While the discrepancies of the max wheel wear depth and wear bandwidth for trailer car are small under different speeds.
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Sang, Hutang, Jing Zeng, Feng Gan, Jian Mu, and Yayun Qi. "A study of wheel wear on a high-speed railway motor car." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, April 26, 2022, 095440972210964. http://dx.doi.org/10.1177/09544097221096467.
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Wheel/rail wear is one of the key issues in the safe operation of a high-speed railway motor car. This paper analyzes and predicts the wheel wear evolution of motor car during the long-term operation process. Firstly, the detailed motor car with gear transmission systems and trailer car of the high-speed train, which take into account various non-linear factors such as dampers, bump stops, wheel/rail contact relation, etc., are developed to obtain interaction force between wheel and rail. Secondly, according to the tread update strategy based on fixed travel distance, a novel wheel wear prediction model integrating the Archard wear model and previous dynamics system is established. In order to more accurately obtain the dynamic responses of the motor car, the comprehensive gear transmission system coupling with motor bogie is also built, which considers the time-varying mesh stiffness and gear shift coefficient. And the corresponding traction characteristic curve is also applied to the gear transmission system. Finally, the wheel wear evolution in one re-profiling cycle is simulated to verify the developed model, and the wheel wear mechanism is investigated in detail. Furthermore, the influence of traction velocity on wheel wear is also investigated. The simulation shows that the cumulative wear amount of both two cars increases gradually and the wear rate decreases gradually with traveling mileage, but the wear rate of the trailer car decreases faster than that of the motor car due to larger longitudinal creepage and longitudinal creep force induced by traction torque. Moreover, the max wheel wear depth and wear bandwidth for motor car gradually increase with traction velocity. While the discrepancies of the max wheel wear depth and wear bandwidth for trailer car are small under different speeds.
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Baheri, Ali, and Chris Vermillion. "Combined Plant and Controller Design Using Batch Bayesian Optimization: A Case Study in Airborne Wind Energy Systems." Journal of Dynamic Systems, Measurement, and Control 141, no. 9 (May 2, 2019). http://dx.doi.org/10.1115/1.4043224.
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This paper presents a novel data-driven nested optimization framework that addresses the problem of coupling between plant and controller optimization. This optimization strategy is tailored toward instances where a closed-form expression for the system dynamic response is unobtainable and simulations or experiments are necessary. Specifically, Bayesian optimization, which is a data-driven technique for finding the optimum of an unknown and expensive-to-evaluate objective function, is employed to solve a nested optimization problem. The underlying objective function is modeled by a Gaussian process (GP); then, Bayesian optimization utilizes the predictive uncertainty information from the GP to determine the best subsequent control or plant parameters. The proposed framework differs from the majority of codesign literature where there exists a closed-form model of the system dynamics. Furthermore, we utilize the idea of batch Bayesian optimization at the plant optimization level to generate a set of plant designs at each iteration of the overall optimization process, recognizing that there will exist economies of scale in running multiple experiments in each iteration of the plant design process. We validate the proposed framework for Altaeros' buoyant airborne turbine (BAT). We choose the horizontal stabilizer area, longitudinal center of mass relative to center of buoyancy (plant parameters), and the pitch angle set-point (controller parameter) as our decision variables. Our results demonstrate that these plant and control parameters converge to their respective optimal values within only a few iterations.