1,720,960 research outputs found
Design and Manufacture of a Multiband Rectangular Spiral-Shaped Microstrip Antenna Using EM-Driven and Machine Learning
No full textThis paper presents a multiband rectangular microstrip antenna using spiral-shaped configurations. The antenna has been designed by combining two configurations of microstrip and spiral with consideration of careful selection of the substrate material, the dimension of the rectangular microstrip, the distance between the turned spiral, and the number of turns of the spiral. The efficiency and accuracy have been improved using machine learning algorithms as well. Machine learning has been studied to model the proposed antenna based on the performance requirements, which requires a sufficient training data to improve the accuracy. Three different machine learning models are applied to improve the accuracy and generalization performance and compared to simulation and measurement results. Simulation, measurement, and machine learning results confirm that the proposed antenna is a new electrically small and operating over a wide range of high-frequency bands between 1 GHz-4 GHz. Machine learning models have the best prediction ability with a mean square error (MSE) of 0.03, and 0.05. The antenna structure and size are compatible and suitable for several multi-band wireless mobile systems operating in L-band and S-band. The results, such as directivity, Half-Power Beamwidth, Voltage Standing Wave Ratio (VSWR), and S-parameter curves, are analysed and compared with the numerical formulation for both spiral and microstrip antennas
Modeling and Simulation of a Frequency Reconfigurable Circular Microstrip Antenna Using PIN Diodes
No full textIn this study, a frequency reconfigurable circular microstrip antenna for wireless communications has been presented. PIN diodes are integrated to obtain multiple-band operation. The operating frequency can be tuned to other frequencies by switching ON/OFF states of the diodes. Many approaches have been explored, which provide multiple wideband operations when integrated with identical microstrips to be regularly controlled. The first one simulates the main circular part without any switching state, then steeply different switching states start. The operating frequencies are between 5 and 15 GHz. It operates exactly in the most tested and demanded dual five-generation (5G) and single industrial, scientific, and medical (ISM) 5.2 GHz bands. The obtained bands are considered for different wireless communication application uses. All results are performed with the method of finite integration technique (FIT)
Reconfigurable Microstrip Antenna Optimization Through Artificial Neural Networks
Get PDF2nd International Conference on Electrical, Communication and Computer Engineering, ICECCE 2020 -- 12 June 2020 through 13 June 2020 -- -- 162684Artificial neural networks are applied to reconfigurable microstrip antenna design and optimization in this paper. The change of resistor value leads to two different results, exploited as the less and the high-performance models and align them as a solution through artificial neural networks. Two phases of optimization are employed by (I) using multilayer perceptron, and (II) prior knowledge input methods. The optimization techniques are implemented through Matlab. In the proposed antenna example, the S-parameter is optimized in separate optimization processes. The proposed reconfigurable microstrip antenna resonates initially at dual-band between 1-5 GHz. The antenna is modified by adding a control circuit included separately two resistors and switches between both conductor parts. By increasing the value of resistors the decrease in the return loss at optimal operating frequencies is observed. © 2020 IEEE
Simülasyona ve bilgi tabanlı yapay sinir ağlarına dayalı hibrid yapı kullanarak yeniden yapılandırılabilir mikroşerit anteni yeni modelenmesi
Get PDFWOS:000582165900009Knowledge-based modeling has a critical role to embed existing knowledge to improve modeling performance. Since reconfigurable antenna can provide more operational frequencies than the classical antennas, a knowledge-based hybrid structure is used in this work to obtain efficient model and producing optimum new models for a reconfigurable microstrip antenna. The hybrid structure consists of two phases. The first phase generates initial knowledge which is used in knowledge-based modeling structure to obtain design parameters. Artificial neural network based multilayer perceptron can generate necessary knowledge for a knowledge-based model after the training process. Knowledge-based modeling improves the accuracy of the initial model to determine design parameters corresponding to the design target. Source difference, prior knowledge Input and prior knowledge input with difference can be applied to realize an efficient knowledge-based strategy. 3D-EM simulation generates the new model in terms of the design parameters of the proposed application. It has three switching states for operating, which are organized by two resistor circuits representing ON/OFF states. Switch positions and geometrical parameters can be used for satisfying design targets between 1 GHz and 6 GHz for the efficient antenna design.Bilgi tabanlı modelleme, modelleme performansını geliştirmek için
mevcut bilgiyi içine katmak için kritik bir role sahiptir. Yeniden
yapılandırılabilir anten, klasik antenlerden daha fazla operasyonel
frekans sağlayabildiğinden, bu çalışmada bilgi tabanlı bir hibrid yapı,
verimli bir model elde etmek ve aynı zamanda yeniden yapılandırılabilir
bir N-şekilli mikroşerit anten (RNSMA) için optimum yeni çözümler
üretmek için kullanılmıştır. Hibrid yapı iki aşamadan oluşmaktadır. İlk
aşama, tasarım parametrelerini elde etmek için bilgi tabanlı modelleme
yapısında kullanılan başlangıç bilgisini üretmektedir. Yapay sinir ağı
tabanlı çok katmanlı algılayıcı, eğitim sürecinden sonra bilgi tabanlı bir
model için gerekli bilgiyi üretebilir. Bilgi tabanlı modelleme, tasarım
hedefine karşılık gelen tasarım parametrelerini belirlemek için
başlangıç modelinin doğruluğunu geliştirir. Verimli bilgi temelli bir
stratejiyi gerçekleştirmek için Ön Bilgi Girişi (PKI), Kaynak Farkı (SD)
ve Ön Bilgi Girişi ile Fark (PKID) uygulanabilir. 3B-EM simülasyonu,
RNSMA'nın tasarım parametrelerine bağlı olarak yeni çözümü üretir.
Önerilen anten, AÇIK/KAPALI durumlarını kullanarak iki direnç devresi
tarafından kontrol edilen üç çalışma moduna sahiptir. Anahtar
konumları ve geometrik parametreler verimli bir anten tasarımı için 1
GHz ve 6 GHz arasında tasarım hedeflerini karşılamak için
kullanılabili
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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