838 research outputs found
Flowfield prediction of airfoil off-design conditions based on a modified variational autoencoder
Airfoil aerodynamic optimization based on single-point design may lead to
poor off-design behaviors. Multipoint optimization that considers the
off-design flow conditions is usually applied to improve the robustness and
expand the flight envelope. Many deep learning models have been utilized for
the rapid prediction or reconstruction of flowfields. However, the flowfield
reconstruction accuracy may be insufficient for cruise efficiency optimization,
and the model generalization ability is also questionable when facing airfoils
different from the airfoils with which the model has been trained. Because a
computational fluid dynamic evaluation of the cruise condition is usually
necessary and affordable in industrial design, a novel deep learning framework
is proposed to utilize the cruise flowfield as a prior reference for the
off-design condition prediction. A prior variational autoencoder is developed
to extract features from the cruise flowfield and to generate new flowfields
under other free stream conditions. Physical-based loss functions based on
aerodynamic force and conservation of mass are derived to minimize the
prediction error of the flowfield reconstruction. The results demonstrate that
the proposed model can reduce the prediction error on test airfoils by 30%
compared to traditional models. The physical-based loss function can further
reduce the prediction error by 4%. The proposed model illustrates a better
balance of the time cost and the fidelity requirements of evaluation for cruise
and off-design conditions, which makes the model more feasible for industrial
applications
RT-LM: Uncertainty-Aware Resource Management for Real-Time Inference of Language Models
Recent advancements in language models (LMs) have gained substantial
attentions on their capability to generate human-like responses. Though
exhibiting a promising future for various applications such as conversation AI,
these LMs face deployment challenges on various devices due to their extreme
computational cost and unpredictable inference latency. Such varied inference
latency, identified as a consequence of uncertainty intrinsic to the nature of
language, can lead to computational inefficiency and degrade the overall
performance of LMs, especially under high-traffic workloads. Unfortunately, the
bandwidth of these uncertainty sources is extensive, complicating the
prediction of latency and the effects emanating from such uncertainties. To
understand and mitigate the impact of uncertainty on real-time
response-demanding systems, we take the first step to comprehend, quantify and
optimize these uncertainty-induced latency performance variations in LMs.
Specifically, we present RT-LM, an uncertainty-aware resource management
ecosystem for real-time inference of LMs. RT-LM innovatively quantifies how
specific input uncertainties, adversely affect latency, often leading to an
increased output length. Exploiting these insights, we devise a lightweight yet
effective method to dynamically correlate input text uncertainties with output
length at runtime. Utilizing this quantification as a latency heuristic, we
integrate the uncertainty information into a system-level scheduler which
explores several uncertainty-induced optimization opportunities, including
uncertainty-aware prioritization, dynamic consolidation, and strategic CPU
offloading. Quantitative experiments across five state-of-the-art LMs on two
hardware platforms demonstrates that RT-LM can significantly reduce the average
response time and improve throughput while incurring a rather small runtime
overhead.Comment: Accepted by RTSS 202
Mode and vibration characteristics of a flexible manipulator with elastic restraint joint
To construct a precise model for investigating the dynamic characteristics and vibration control strategies of flexible manipulators, restraints of the joint should be fully considered and precisely described. Considering the effect of the elastic restraints of the joint, this paper investigated the mode and vibration characteristics of a flexible manipulator with elastic restraint joint (FMERJ). The elastic restraint model and boundary conditions of the FMERJ were established. With the boundary conditions, natural frequency equation and mode shapes of the FMERJ were derived. Subsequently, vibration responses of the FMERJ were obtained. Numerical results demonstrated that the mode and vibration characteristics of the FMERJ are obviously different from that of flexible manipulator with fixed restraint joint (FMFRJ) which was commonly idealized in present research, and the elastic restraints of the joint have a considerable effect on the dynamic characteristics and should be considered in precise dynamic analysis and further constructing vibration control strategies of the flexible manipulator
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