scholarly journals Modal Density in Structuring Segments Containing Organizational Metadiscourse Versus Content Sequences

ESP Today ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 2-21
Author(s):  
Edgar Bernad-Mechó
Keyword(s):  
2011 ◽  
Vol 189-193 ◽  
pp. 1914-1917
Author(s):  
Lin Ji

A key assumption of conventional Statistical Energy Analysis (SEA) theory is that, for two coupled subsystems, the transmitted power from one to another is proportional to the energy differences between the mode pairs of the two subsystems. Previous research has shown that such an assumption remains valid if each individual subsystem is of high modal density. This thus limits the successful applications of SEA theory mostly to the regime of high frequency vibration modeling. This paper argues that, under certain coupling conditions, conventional SEA can be extended to solve the mid-frequency vibration problems where systems may consist of both mode-dense and mode-spare subsystems, e.g. ribbed-plates.


2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Hua Zheng ◽  
Junhao Liu ◽  
Shiqiang Duan

Flutter tests are conducted primarily for the purpose of modal parameter estimation and flutter boundary prediction, the accuracy of which is severely affected by the acquired data quality, structural modal density, and nonstationary conditions. An improved Hilbert-Huang Transform (HHT) algorithm is presented in this paper which mitigates the typical mode mixing effect via modulation. The algorithm is validated by theory, by numerical simulation, and per actual flight flutter test data. The results show that the proposed method could extract the flutter model parameters and predict the flutter speed more accurately, which is feasible for the current flutter test data processing.


1971 ◽  
Vol 93 (3) ◽  
pp. 783-792 ◽  
Author(s):  
Denys J. Mead

The vibration response of periodic, beam-like structures has conventionally been studied either by transfer matrix or normal mode methods. The latter method becomes unwieldy if the damping and modal density are high, whereas the former method does not lend itself readily to giving physical understanding. It is shown in this paper that a special class of flexural wave groups can exist in periodic structures; an understanding of them permits a ready formulation of the response-calculation problem. The formulation can be applied to both infinite and finite structures, and the amount of damping present may have any value. The method is specially well adapted to studying response due to convected pressure fields and loadings and gives great physical insight. Illustrations are given relating to beams resting at regular intervals on flexible supports and to aeronautical rib-skin structures. Some calculated values of vibration response are presented and discussed and optimum structural configurations are considered.


2020 ◽  
Vol 5 (2) ◽  
pp. 76-110
Author(s):  
Ajay Rastogi ◽  
Monica Mehrotra ◽  
Syed Shafat Ali

AbstractPurposeThis paper aims to analyze the effectiveness of two major types of features—metadata-based (behavioral) and content-based (textual)—in opinion spam detection.Design/methodology/approachBased on spam-detection perspectives, our approach works in three settings: review-centric (spam detection), reviewer-centric (spammer detection) and product-centric (spam-targeted product detection). Besides this, to negate any kind of classifier-bias, we employ four classifiers to get a better and unbiased reflection of the obtained results. In addition, we have proposed a new set of features which are compared against some well-known related works. The experiments performed on two real-world datasets show the effectiveness of different features in opinion spam detection.FindingsOur findings indicate that behavioral features are more efficient as well as effective than the textual to detect opinion spam across all three settings. In addition, models trained on hybrid features produce results quite similar to those trained on behavioral features than on the textual, further establishing the superiority of behavioral features as dominating indicators of opinion spam. The features used in this work provide improvement over existing features utilized in other related works. Furthermore, the computation time analysis for feature extraction phase shows the better cost efficiency of behavioral features over the textual.Research limitationsThe analyses conducted in this paper are solely limited to two well-known datasets, viz., YelpZip and YelpNYC of Yelp.com.Practical implicationsThe results obtained in this paper can be used to improve the detection of opinion spam, wherein the researchers may work on improving and developing feature engineering and selection techniques focused more on metadata information.Originality/valueTo the best of our knowledge, this study is the first of its kind which considers three perspectives (review, reviewer and product-centric) and four classifiers to analyze the effectiveness of opinion spam detection using two major types of features. This study also introduces some novel features, which help to improve the performance of opinion spam detection methods.


2000 ◽  
Vol 6 (3) ◽  
pp. 207-221 ◽  
Author(s):  
Michael D. Robinson ◽  
Joel T. Johnson ◽  
David A. Robertson

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