1,720,958 research outputs found
Microstrip patch antenna design for 5G communication technology
No full textFen Bilimleri Enstitüsü, Elektrik-Elektronik Mühendisliği Ana Bilim DalıBu tezde 5G teknolojisi için 28 GHz ve 38 GHz frekanslarında birçok Dikdörtgen Mikroşerit Anten (DMŞA) tasarım ve benzetimi yapılmıştır. Bütün tasarımlar 3 boyutlu bir elektromanyetik benzetim programı olan ANSYS HFSS (High-Frequency Structure Simulator) yazılımı kullanılarak oluşturulmuş ve benzetim gerçekleştirilmiştir. İçeriden temassız ve yakınlık kuplajlı besleme yöntemi kullanılarak 28 GHz tek DMŞA, 28/38 GHz çift bantlı DMŞA ve dizi DMŞA tasarımları yapılmıştır. İlaveten, bu tasarımların toprak yüzeyine Halka, Çubuk, Halka/Çubuk şeklinde yarıklar açılarak ya da parazit yama elemanı anten yapısına eklenerek DMŞA tasarımlarının bant genişliği arttırılmıştır. Simülasyon sonuçları literatürdeki benzer çalışmalarla karşılaştırılmış olup, 28 GHz tek DMŞA, 28/38 GHz DMŞA ve dizi DMŞA tasarımlarında bant genişliği, kazanç, geri dönüş kaybı gibi anten parametrelerinin iyileştirildiği gözlemlenmiştir. 28/38 GHz çift bantlı tek DMŞA tasarımları literatürde bulunan ve referans alınan bazı çalışmalara göre daha düşük bant genişliğine sahip olsa da çift frekans için yüksek kazançlara sahiptir. İçeriden temassız besleme yöntemi kullanılarak çeşitli BTY(Bozulmuş toprak yüzeyi) yapılarına sahip birçok 1×2 dizi DMŞA tasarımı yapılmıştır. Bu tasarımlar arasından Halka/Çubuk şeklinde BTY'e sahip yığın 1×2 dizi DMŞA tasarımı 28 GHz için geniş bantta ve yüksek kazanca sahiptir. Tezdeki son tasarım olarak bozulmuş toprak yüzeyli içeriden temassız beslenen 1×4 dizi DMŞA yapısı oluşturulmuştur. Toprak yüzeyine halka şekillerinde kusurlar oluşturularak 28 GHz için 1×4 DMŞA dizisinin bant genişliği arttırılmıştır.In this study, several Rectangular Microstrip Antennas (RMA) are designed and simulated for 5G technology at frequencies 28 and 38 GHz. All presented designs are constructed and simulated by using Ansys HFSS 3D electromagnetic (EM) simulation software. By using non-contacting insert feeding or proximity coupling technique, at 28 GHz single, 28/38 GHz dual-band single element and array type RMA designs are constructed. Moreover, the bandwidth of RMAs has been increased by slotting Rings, Rods, Rings/Rods on the ground surface, or adding a parasitic element to the antenna structure. Simulation results are compared with similar studies in the literature and from these comparisons, it has been seen that output antenna parameters such as bandwidth, gain, or return loss are improved very well for at 28 GHz single element and at 28/38 GHz array type RMA designs. Although the bandwidth for a single element at 28/38 GHz Dual Band RMA designs is not as high as some reference studies given in comparisons, RMA designs given in those studies have very low gain or high return loss which are not desired for a high-efficiency antenna. The several 1×2 array RMA designs with various DGS (Defected ground structure) structures have been designed using the a non-contacting feeding method. Among these designs, the stacked 1×2 array RMA design with Ring/Rod-shaped DGS was compared with reference antennas, and it was concluded that it had broadband and high gain for 28 GHz. As the last design in the thesis, non-contacting insert feeding array 1×4 RMA Structure with DGS was created. The bandwidth of the 1×4 RMA array for 28 GHz has been increased by creating ring-shaped defects on the ground surface
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
The Effect of Substrate Dielectric Constant and Thickness on Millimeter Wave Band Patch Antenna Performance
No full textIn last decade, the fifth generation of telecom network (5G) has been a new era as a result of fast-growing mobile industry. Unlike its predecessors, 5G will not only provide faster, better mobile broadband experience, but also broaden communication network with new services such as device-to-device communications or connecting IoT devices and users. For this purpose, 5G aims to achieve massive network capacity, ultra-low latency, higher data speed and greater network reliability. According to the report of ITU World Radiocommunication Conference 2019 (WRC-19), several new frequency bands between 20-70 GHz, were announced for allocation of 5G. Frequencies in the Ka-band (27-40 GHz) are particularly attractive due to their low atmospheric attenuation. At the specified frequency range i.e., millimeter wave band, antenna design for 5G applications is very crucial to provide high gain and efficiency as well as broadband communication which is indispensable for high-speed data traffic. At this point, Microstrip patch antennas, stand out amongst others because of their numerous attractive features. In this work, the effect of substrate dielectric constant and thickness to the Rectangular Microstrip Antenna (RMA) performance is examined for high frequency 5G applications. The RMA is designed to operate at 38 GHz and antenna performance has been analyzed according to various dielectric substrates, such as RT5880, RO3003, FR4, RT6006 and RT6010, considering different dielectric constants, thicknesses, and tangential losses. All designs and analyses have been accomplished by using ANSYS HFSS (High-Frequency Structure Simulator) and comparative results of the work are presented
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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