1109 Study on Effects of Various Parameters on Flutter Speed (Prediction of Flutter Speed due to Theoretical Analysis)

Deep learning technology has been widely used in various field in recent years. This study intends to use deep learning algorithms to analyze the aeroelastic phenomenon and compare the differences between Deep Neural Network (DNN) and Long Short-term Memory (LSTM) applied on the flutter speed prediction. In this present work, DNN and LSTM are used to address complex aeroelastic systems by superimposing multi-layer Artificial Neural Network. Under such an architecture, the neurons in neural network can extract features from various flight data. Instead of time-consuming high-fidelity computational fluid dynamics (CFD) method, this study uses the K method to build the aeroelastic flutter speed big data for different flight conditions. The flutter speeds for various flight conditions are predicted by the deep learning methods and verified by the K method. The detailed physical meaning of aerodynamics and aeroelasticity of the prediction results are studied. The LSTM model has a cyclic architecture, which enables it to store information and update it with the latest information at the same time. Although the training of the model is more time-consuming than DNN, this method can increase the memory space. The results of this work show that the LSTM model established in this study can provide more accurate flutter speed prediction than the DNN algorithm.

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Full-Span Flying Wing Wind Tunnel Test: A Body Freedom Flutter Study

Fluids ◽

10.3390/fluids5010034 ◽

2020 ◽

Vol 5 (1) ◽

pp. 34

Author(s):

Pengtao Shi ◽

Jihai Liu ◽

Yingsong Gu ◽

Zhichun Yang ◽

Pier Marzocca

Keyword(s):

Wind Tunnel ◽

Theoretical Analysis ◽

Mass Balance ◽

Degrees Of Freedom ◽

Wind Tunnel Test ◽

Suspension System ◽

The Body ◽

Structural Dynamic ◽

Flutter Speed ◽

Theoretical Results

Aiming at the experimental test of the body freedom flutter for modern high aspect ratio flexible flying wing, this paper conducts a body freedom flutter wind tunnel test on a full-span flying wing flutter model. The research content is summarized as follows: (1) The full-span finite element model and aeroelastic model of an unmanned aerial vehicle for body freedom flutter wind tunnel test are established, and the structural dynamics and flutter characteristics of this vehicle are obtained through theoretical analysis. (2) Based on the preliminary theoretical analysis results, the design and manufacturing of this vehicle are completed, and the structural dynamic characteristics of the vehicle are identified through ground vibration test. Finally, the theoretical analysis model is updated and the corresponding flutter characteristics are obtained. (3) A novel quasi-free flying suspension system capable of releasing pitch, plunge and yaw degrees of freedom is designed and implemented in the wind tunnel flutter test. The influence of the nose mass balance on the flutter results is explored. The study shows that: (1) The test vehicle can exhibit body freedom flutter at low airspeeds, and the obtained flutter speed and damping characteristics are favorable for conducting the body freedom flutter wind tunnel test. (2) The designed suspension system can effectively release the degrees of freedom of pitch, plunge, and yaw. The flutter speed measured in the wind tunnel test is 9.72 m/s, and the flutter frequency is 2.18 Hz, which agree well with the theoretical results (with flutter speed of 9.49 m/s and flutter frequency of 2.03 Hz). (3) With the increasing of the mass balance at the nose, critical speed of body freedom flutter rises up and the flutter frequency gradually decreases, which also agree well with corresponding theoretical results.

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Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055680 ◽

1982 ◽

Vol 40 ◽

pp. 668-669

Author(s):

A. Gómez ◽

P. Schabes-Retchkiman ◽

M. José-Yacamán ◽

T. Ocaña

Keyword(s):

Experimental Data ◽

Electron Diffraction ◽

Theoretical Analysis ◽

Size Range ◽

Dynamical Theory ◽

Metallic Particles ◽

Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

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Theoretical analysis of a monopole antenna with conducting flat disk above the earth

Electronics and Communications in Japan (Part I Communications) ◽

10.1002/ecja.1021.abs ◽

2001 ◽

Vol 84 (7) ◽

pp. 27-36

Author(s):

Aki Yuasa ◽

Daisuke Itatsu ◽

Naoki Inagaki ◽

Nobuyoshi Kikuma

Keyword(s):

Theoretical Analysis ◽

Monopole Antenna ◽

The Earth ◽

Flat Disk

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Context Aversion, Pavlovian Conditioning, and the Psychological Side Effects of Chemotherapy

European Psychologist ◽

10.1027/1016-9040.2.118 ◽

1997 ◽

Vol 2 (2) ◽

pp. 118-124

Author(s):

Geoffrey Hall

Keyword(s):

Animal Model ◽

Side Effects ◽

Theoretical Analysis ◽

Conditioned Response ◽

Behavioral Strategies ◽

Contextual Cues ◽

Anticipatory Nausea ◽

Laboratory Rats ◽

Anticipatory Nausea And Vomiting ◽

Parallel Case

Patients who have undergone several sessions of chemotherapy for cancer will sometimes develop anticipatory nausea and vomiting (ANV), these unpleasant side effects occurring as the patients return to the clinic for a further session of treatment. Pavlov's analysis of learning allows that previously neutral cues, such as those that characterize a given place or context, can become associated with events that occur in that context. ANV could thus constitute an example of a conditioned response elicited by the contextual cues of the clinic. In order to investigate this proposal we have begun an experimental analysis of a parallel case in which laboratory rats are given a nausea-inducing treatment in a novel context. We have developed a robust procedure for assessing the acquisition of context aversion in rats given such training, a procedure that shows promise as a possible animal model of ANV. Theoretical analysis of the conditioning processes involved in the formation of context aversions in animals suggests possible behavioral strategies that might be used in the alleviation of ANV, and we report a preliminary experimental test of one of these.

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