Modeling and Simulation of Big Pendulum Hammer with Natural Coordinates

2013 ◽  
Vol 753-755 ◽  
pp. 1016-1019
Author(s):  
Ke Wei Zhang ◽  
Zhi Gang Hu ◽  
Peng Wei Guo
Keyword(s):  
Selection Method ◽  
Natural Coordinates ◽  
Step Method ◽  
Natural Coordinate System ◽  
Self Adaptation ◽  
Natural Coordinate ◽  
Step Selection ◽  
Adaptation Method ◽  
Rigid Element ◽  
Selection Of

The dynamic of a type of play equipment, Big Pendulum Hammer, was modeled and simulated in computer and the approach of natural coordinates was adopted to build its equation of motion. In order to obtain appropriate natural coordinates, a two-step selection method was chosen, which based on concept of natural coordinate system (NCS). The two-step method treats selecting natural coordinates for a rigid element as building an actual NCS which should be adapted from a standard NCS. In order to automate the process of adaptation for 18 rigid elements in the model of Big Pendulum Hammer, a four-step self-adaptation method was also adopted, which can help automate the selection of natural coordinates for multi-rigidbody systems.

Self-Adaptation of Natural-Coordinate System

2013 ◽  
Vol 367 ◽  
pp. 286-291
Author(s):  
Ke Wei Zhang ◽  
Yun Qing Zhang
Keyword(s):  
Coordinate System ◽  
Equal Weight ◽  
Natural Coordinates ◽  
Model Quality ◽  
Step Method ◽  
Natural Coordinate System ◽  
Self Adaptation ◽  
Natural Coordinate ◽  
Analysis Platform ◽  
Adaptation Method

A self-adaptation method for natural-coordinate systems is proposed, in order to automate the selection of natural coordinates for each rigid element of a multibody system. The four-step method includes: First, find out all empty positions, which come from the feature points or vectors of the joints attached to the element, and give equal weight to them; second, delete redundant empty positions and add their weight to the unique one; third, select at most four empty positions which have a maximum total weight and can be occupied by a natural-coordinate system at the same time; fourth, the standard natural-coordinate system on the element can adapt itself to the selected empty positions, leading to an actual natural-coordinate system, which contains twelve rational natural coordinates for the element. The implementation of the method has been achieved on a multibody dynamics and motion analysis platform, InteDyna, with the result that modeling efficiency is enhanced and model quality improved.

scholarly journals Special Finite Elements with Adaptive Strain Field on the Example of One-Dimensional Elements

2021 ◽  
Vol 11 (2) ◽  
pp. 609
Author(s):  
Tadeusz Chyży ◽  
Monika Mackiewicz
Keyword(s):  
Finite Elements ◽  
Strain Field ◽  
Main Idea ◽  
Deformation Field ◽  
Geometrical Parameters ◽  
Single Element ◽  
One Dimensional ◽  
New Type ◽  
Self Adaptation ◽  
Adaptation Method

The conception of special finite elements called multi-area elements for the analysis of structures with different stiffness areas has been presented in the paper. A new type of finite element has been determined in order to perform analyses and calculations of heterogeneous, multi-coherent, and layered structures using fewer finite elements and it provides proper accuracy of the results. The main advantage of the presented special multi-area elements is the possibility that areas of the structure with different stiffness and geometrical parameters can be described by single element integrated in subdivisions (sub-areas). The formulation of such elements has been presented with the example of one-dimensional elements. The main idea of developed elements is the assumption that the deformation field inside the element is dependent on its geometry and stiffness distribution. The deformation field can be changed and adjusted during the calculation process that is why such elements can be treated as self-adaptive. The application of the self-adaptation method on strain field should simplify the analysis of complex non-linear problems and increase their accuracy. In order to confirm the correctness of the established assumptions, comparative analyses have been carried out and potential areas of application have been indicated.

The academic English collocation list

2018 ◽  
Vol 23 (2) ◽  
pp. 216-243 ◽  
Author(s):  
Lei Lei ◽  
Dilin Liu
Keyword(s):  
Selection Method ◽  
Academic English ◽  
Efl Learners ◽  
Innovative Research ◽  
Step Selection ◽  
Large Corpus

Abstract The use of collocations plays an important role for the proficiency of ESL/EFL learners. Hence, educators and researchers have long tried to identify collocations typical of either academic or general English and the challenges involved in learning them. This paper proposes a comprehensive and type-balanced academic English collocation list (AECL). AECL is based on a large corpus of academic English and was created to cover the types of collocations that will be most useful to ESL/EFL learners. AECL is the result of an innovative research-based procedure that involves a five-step selection method. A comparison of the collocations on AECL with those found in well-known collocation dictionaries of general English and on three existing academic English collocation lists indicates that AECL indeed contains mainly academic rather than general English collocations. In addition, AECL is more comprehensive with regard to the types of collocations that are relevant to learners.

A Skywave OTHR Adaptive Frequency Selection Method Based on Preliminary Criterion and Weighted Criterion

2014 ◽  
Vol 1061-1062 ◽  
pp. 974-977
Author(s):  
Shi Hua Liu ◽  
Xian Gang Liu ◽  
Zhi Jian Sun
Keyword(s):  
Selection Criterion ◽  
Selection Method ◽  
Frequency Selection ◽  
Selection Of

A skywave radar adaptive frequency selection method based on the preliminary criterion and the weighted criterion is presented. In this method, according to the various operational tasks, the frequency selection criterion is divided into the preliminary criterion and the weighted criterion based on the characteristic of the targets. The adaptive frequency selection of the skywave radar is achieved by the weighted computed of the frequency selection criterion. The feasibility and availability is demonstrated by an example.

scholarly journals Why, sometimes, primaries? Intraparty democratization as a default selection mechanism in German and Spanish mainstream parties

2018 ◽  
Vol 26 (5) ◽  
pp. 594-604 ◽  
Author(s):  
Javier Astudillo ◽  
Klaus Detterbeck
Keyword(s):  
Political Parties ◽  
Selection Method ◽  
Regional Level ◽  
Selection Mechanism ◽  
Leadership Selection ◽  
Limited Knowledge ◽  
Western Democracies ◽  
Selection Of

In many Western democracies, political parties have started to open to members the selection of their leaders. While most studies focus on the introduction of this new selection method, its subsequent practice is still understudied. The article contributes to our still limited knowledge of this process by looking at two multilevel countries, Germany and Spain, where the mainstream parties have sometimes organized membership ballots, especially at the regional level, for leadership selection. Thanks to two original databases on party conferences and membership ballots, the article analyzes the background of this process and reviews the most common explanations offered by the literature. It shows that they are not held when parties want to regain power, or party chairs seek their nomination, as commonly believed, but when there are intraparty leadership disputes.

LED for hyperspectral imaging – a new selection method

2018 ◽  
Vol 63 (5) ◽  
pp. 529-535 ◽  
Author(s):  
Tobias Heimpold ◽  
Frank Reifegerste ◽  
Stefan Drechsel ◽  
Jens Lienig
Keyword(s):  
Hyperspectral Imaging ◽  
Power Distribution ◽  
Spectral Power ◽  
Selection Process ◽  
Selection Method ◽  
Light Emitting ◽  
Spectral Power Distribution ◽  
Forward Current ◽  
Efficient Selection ◽  
Selection Of

AbstractHyperspectral imaging (HSI) has become a sophisticated technique in modern applications such as food analyses, recycling technology, medicine, pharmacy and forensic science. It allows one to analyse both spatial and spectral information from an object. But hyperspectral cameras are still expensive due to their extended wavelength range. The development of new light-emitting diodes (LED) in the recent past enables another approach to HSI using a monochrome camera in combination with a LED-based illumination. However, such a system has a lower spectral resolution. Additionally, the growing supply of LED on the market complicates the selection of LED. In this paper, we propose a new time efficient selection method for the design process of an illumination. It chooses an optimised LED combination from an existing database to match a predefined spectral power distribution. Therefore, an algorithm is used to evaluate various LED combinations. Furthermore, the method considers the spectral behaviour of each LED in dependence of forward current and temperature of the solder point. Our method has already shown promise during the selection process for even spectral distributions which is demonstrated in the study. Additionally, we will show its potential for HSI illuminations.

scholarly journals Arabic Query Expansion Using WordNet and Association Rules

2016 ◽  
Vol 12 (3) ◽  
pp. 51-64 ◽  
Author(s):  
Ahmed Abbache ◽  
Farid Meziane ◽  
Ghalem Belalem ◽  
Fatma Zohra Belkredim
Keyword(s):  
Performance Improvement ◽  
Association Rules ◽  
Query Expansion ◽  
Arabic Language ◽  
Selection Method ◽  
Retrieval Performance ◽  
Retrieval Systems ◽  
Information Retrieval Systems ◽  
Significant Performance ◽  
Selection Of

Query expansion is the process of adding additional relevant terms to the original queries to improve the performance of information retrieval systems. However, previous studies showed that automatic query expansion using WordNet do not lead to an improvement in the performance. One of the main challenges of query expansion is the selection of appropriate terms. In this paper, the authors review this problem using Arabic WordNet and Association Rules within the context of Arabic Language. The results obtained confirmed that with an appropriate selection method, the authors are able to exploit Arabic WordNet to improve the retrieval performance. Their empirical results on a sub-corpus from the Xinhua collection showed that their automatic selection method has achieved a significant performance improvement in terms of MAP and recall and a better precision with the first top retrieved documents.

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