Electrically assisted turbochargers(EAT)improve intake efficiency by motor-assisted compressor impeller rotation,enhancing the system's transient ***,the addition of motor rotor components has increased the number...
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Electrically assisted turbochargers(EAT)improve intake efficiency by motor-assisted compressor impeller rotation,enhancing the system's transient ***,the addition of motor rotor components has increased the number of unbalanced positions in the shaft system,leading to problems such as excessive compressor end vibration and complex changes in oil film *** evaluate the effects of unbalance in the motor rotor,along with the parameters of floating ring bearings(FRB),on the dynamic response of EAT,a finite element model of an EAT rotor supported by nonlinear FRB is developed,and the vibration response of the compressor end bearing is obtained by numerical *** results indicate:(1)In contrast to the effect of compressor and turbine unbalance,proper motor rotor unbalance is more effective in suppressing oil whirl instability in the high-speed operating ***,a new inner oil film whirl“instability interval”is also induced in the low-speed operating range,leading to an increase in the Y1 compressor-end amplitude at low and medium speeds,and this“instability interval”increases with the amount of unbalance.(2)When an oil whirl occurs in the oil film,the maximum eccentricity of the bearing surges and is greater than 0.3,which can be used as an effective threshold for determining whether the oil film is unstable in engineering applications.(3)A suitable outer oil-film clearance range should be 35–40μm,otherwise,a wide range of outer oil-film whirl instability *** the amount of unbalance and oil-film clearance to suppress the subsynchronous vibration of the EAT,provides a theoretical basis for the design of the dynamics of the nonlinear rotor bearing system and improves the stability of the turbocharger's operation.
Spatial modulation (SM) is a low-complexity multiple-input/multiple-output transmission technique that combines index modulation and quadrature amplitude modulation for wireless communications. In this work, we consid...
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Displacement is a critical indicator for mechanical systems and civil *** vision-based displacement recognition methods mainly focus on the sparse identification of limited measurement points,and the motion representa...
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Displacement is a critical indicator for mechanical systems and civil *** vision-based displacement recognition methods mainly focus on the sparse identification of limited measurement points,and the motion representation of an entire structure is very *** study proposes a novel Nodes2STRNet for structural dense displacement recognition using a handful of structural control nodes based on a deformable structural three-dimensional mesh model,which consists of control node estimation subnetwork(NodesEstimate)and pose parameter recognition subnetwork(Nodes2PoseNet).NodesEstimate calculates the dense optical flow field based on FlowNet 2.0 and generates structural control node ***2PoseNet uses structural control node coordinates as input and regresses structural pose parameters by a multilayer perceptron.A self-supervised learning strategy is designed with a mean square error loss and L2 regularization to train *** effectiveness and accuracy of dense displacement recognition and robustness to light condition variations are validated by seismic shaking table tests of a four-story-building *** studies with image-segmentation-based Structure-PoseNet show that the proposed Nodes2STRNet can achieve higher accuracy and better robustness against light condition *** addition,NodesEstimate does not require retraining when faced with new scenarios,and Nodes2PoseNet has high self-supervised training efficiency with only a few control nodes instead of fully supervised pixel-level segmentation.
Machine tool spindles, complex dynamic systems under thermal growth, are significantly influenced by the shaft assembly’s dimensions, including the spindle shaft and various press-fit auxiliary components. Despite th...
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Machine tool spindles, complex dynamic systems under thermal growth, are significantly influenced by the shaft assembly’s dimensions, including the spindle shaft and various press-fit auxiliary components. Despite the importance of these dimensions, their effects on the spindle’s dynamic and thermo-mechanical behavior have yet to be sufficiently explored. This study employed a detailed sensitivity analysis for numerous auxiliary components to identify dimensions that most effectively improve the frequency response function (FRF) and minimize thermal growth. The dynamic and thermal analyses were conducted using the receptance coupling substructure analysis (RCSA) and a reduced-order model of finite element model (ROM-FEM), respectively. The findings revealed that, for the considered design, the front stepped sleeve, spindle tail components, and the shaft’s central hole are the most sensitive elements that offer an opportunity to improve spindle performance after bearing optimization.
Large persistent memory is crucial for many applications in embedded systems and automotive computing like AI databases, ADAS, and cutting-edge infotainment systems. Such applications require reliable NAND flash memor...
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Abstract: We consider a system of two nonlinear second-order parabolic equations with *** of this type are applied in chemical kinetics to describe reaction-diffusion processes. Weprove the existence and uniqueness th...
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A high‐fidelity multibody‐system dynamic model of the looped tether transportation system(L‐TTS)is proposed in this study to study its large deformation as well as large overall *** absolute nodal coordinate formul...
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A high‐fidelity multibody‐system dynamic model of the looped tether transportation system(L‐TTS)is proposed in this study to study its large deformation as well as large overall *** absolute nodal coordinate formulation(ANCF)‐based gradient‐deficient beam element is employed to establish the accurate model of the two flexible tethers subject to large *** relative movement of climbers along tethers is described by using the sliding joint model based on *** reduce the collision risks between tethers and climbers,two libration suppression strategies,namely,the decelerated motion of climbers relative to tethers and multiple climbers per tether are investigated in this *** numerical simulations not only validate the effectiveness of the two strategies in reducing the collision risks between climbers and tethers,the overall librations of L‐TTS,and the magnitudes of the longitudinal elastic force of tethers,but also verify the good performance of the high‐fidelity model proposed in this study for dynamic simulation of the L‐TTS in microgravity conditions.
This paper proposes a modified iterative learning control(MILC)periodical feedback-feedforward algorithm to reduce the vibration of a rotor caused by coupled unbalance and parallel *** control of the vibration of the ...
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This paper proposes a modified iterative learning control(MILC)periodical feedback-feedforward algorithm to reduce the vibration of a rotor caused by coupled unbalance and parallel *** control of the vibration of the rotor is provided by an active magnetic actuator(AMA).The iterative gain of the MILC algorithm here presented has a self-adjustment based on the magnitude of the *** filters are adopted to extract the synchronous(1×Ω)and twice rotational frequency(2×Ω)components of the rotor *** the notch frequency of the filter and the size of feedforward storage used during the experiment have a real-time adaptation to the rotational *** method proposed in this work can provide effective suppression of the vibration of the rotor in case of sudden changes or fluctuations of the rotor *** and experiments using the MILC algorithm proposed here are carried out and give evidence to the feasibility and robustness of the technique proposed.
This paper describes the design and evaluation of an autoflight controller under maximized crosswind landing scenarios using Nonlinear Dynamic Inversion (NDI) and Incremental Nonlinear Dynamic Inversion (INDI) control...
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Traction parameters, that characterize the ground-wheel contact dynamics, are the central factor in the energy efficiency of vehicles. To optimize fuel consumption, reduce wear of tires, increase productivity etc., kn...
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