1,356,738 research outputs found
Parasitic effects of the metallic towers on the characteristics of the broadcast antennas
Full text linkIn this article, we use a tool NEC (Numerical Electromagnetic Code) to model antenna on top of a tower structure. Simulation results for the parasitic effect of the tower on characteristics of broadcast DVB‐T (Digital Video Broadcasting Terrestrial) antenna such as input impedance, return loss, gain, front‐to‐back ratio and radiation patterns are reported. In addition, the effect of a nearby tower on antenna characteristics is studied. A 3D tower and broadband antenna in the UHF (470‐862) MHz band are constructed. The antenna works for both digital and analog TV with return loss (RL) ≥ 10 dB, fractional bandwidth of 87% and gain of 12.3 dBi at center frequency. The effective radiated power is calculated by mounting the antenna at each face of the tower to give a satisfactory coverage to a region around the antenna
Manufacturing automation : metal cutting mechanics, machine tool vibrations, and CNC design / Yusuf Altintas.
No full textengineering bookfair2015Includes bibliographical references and index.xii, 366 pages :"Metal cutting is a widely used method of producing manufactured products. The technology of metal cutting has advanced considerably along with new materials, computers, and sensors. This new edition treats the scientific principles of metal cutting and their practical application to manufacturing problems. It begins with metal cutting mechanics, principles of vibration, and experimental modal analysis applied to solving shop floor problems. Notable is the in-depth coverage of chatter vibrations, a problem experienced daily by manufacturing engineers. The essential topics of programming, design, and automation of CNC (computer numerical control) machine tools, NC (numerical control) programming, and CAD/CAM technology are discussed. The text also covers the selection of drive actuators, feedback sensors, modeling and control of feed drives, the design of real time trajectory generation and interpolation algorithms, and CNC-oriented error analysis in detail. Each chapter includes examples drawn from industry, design projects, and homework problems. This book is ideal for advanced undergraduate and graduate students, as well as practicing engineers"--Provided by publisher
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
Relationships between natural environment and human ın altintas river watershed
No full textAraştırma alanını teşkil eden Altıntaş Çayı Havzası ve çevresinin büyük bölümü Ege Bölgesi’nin İç Batı Anadolu Bölümü’nde yer almaktadır. Ayrıca saha, idari bakımdan Afyonkarahisar, Kütahya, Uşak ve Eskişehir illeri sınırlarında bulunmaktadır.
İnceleme alanının kuzeyinde Kocadağ (1552 m) ve Kulaksız Dağı (1558 m) yer almaktadır. Saha, güneyden Kartal Tepe (1442 m), batıdan Tava Dağı ve doğudan Kalankaya Tepe (1361 m) ile çevrilidir. Altıntaş Çayı Havzası kendisini çevreleyen yükseltiler ile güneyden Banaz Çayı Havzası’ndan, kuzeyde Porsuk Çayı Havzası’ndan, doğuda Şeydiler Çayı Havzası’ndan ve güneydoğudan Akarçay Kapalı Havzası’ndan ayrılmaktadır.
Araştırma alanındaki Paleozoik yaşlı araziler güneyde, Afyon-İhsaniye dolaylarında, Mesozoik araziler aşınmanın uygun olduğu Kütahya batısında, Kütahya- Afyon karayolunun üzerinde yüzeylenmektedir. İnceleme alanında yaygın birimleri genellikle Pliyosen ve Miyosen gölsel ve volkanik kayaçlar oluşturur. Sahada hakim olan kayaç türleri kireçtaşı ve volkanik birimlerdir. Alüvyonlar, ova tabanlarını örtmektedir.
Araştırma alanında yer alan ve onu çevreleyen dağlık kütleler arasında önemli yükselti farkları bulunmamaktadır. Sahadaki en önemli yükseltiyi batıda yer alan Murat Dağı (2309 m.) oluşturur. Altıntaş Çayı’nın suladığı iki önemli ova Altıntaş ve Aslanapa ovaları olup, bu alanlar tarım açısından önemli sahaları oluşturmaktadır.
Altıntaş Çayı Havzası ve çevresinde Akdeniz İklimi’nden uzak İç Anadolu Bölgesi’nde görülen karasal iklime yakın bir iklim hakimdir. Bu nedenle yaz mevsiminde güneşli, yağışsız, sıcak günler etkili olmakta ve buna bağlı olarak ta kuraklık etkisini göstermektedir. Fakat Ekim ayından itibaren sıcaklıklar düşmekte, basınç değerleri yükselmektedir. Altıntaş’ta yıllık ortalama sıcaklık 10,6 °C, yıllık yağış miktarı 430 mm dir.
Sahada başlıca akarsu şebekesini Altıntaş Çay ve kolları oluşturmaktadır. Bu akarsular Altıntaş ve Aslanapa gibi ovaları sulamaktadır.
Sahanın bitki örtüsünü antropojen step ve kuru ormanlar oluşturur. Ova tabanlarında antropojen step, yüksek kesimlerde kuru ormanlar yer alır.
Araştırma alanı geçmişten günümüze kadar geçici ve daimi yerleşmelere ev sahipliği yapmış bir alana karşılık gelmektedir. Sahada, Antik Dönem’in en eski ve önemli medeniyetini Frigyalılar kurmuştur. Bu nedenle bu dönemde saha "Frigya" adıyla anılır. Bölgede sırayla Kimmer, Pers, İyon, Roma ve Bizans krallıkları yaşamıştır. Altıntaş İlçesi’nde bu dönemlerden kalma höyük, Tümülüs ve Nekropol denilen ahit ve anıt mezarlar bulunmuştur.
Kütahya 8 Ekim 1923’te vilayet olmuş, Altıntaş ise 1947 yılında ilçe statüsü kazanmıştır. İlçe, 5 mahalle, 2 belde ve 33 köyden oluşmaktadır. 2000 yılı genel nüfus sayımı sonuçlarına göre ilçenin nüfusu 25262 kişidir. Bunun 6418 i ilçe merkezi, 2287 si Çayırbaşı Beldesi, 2449 u Zafertepeçalköy Beldesi ve 14108 i köylerde yaşamaktadır.
Kurtuluş Savaşı’nın en önemli çarpışmalarından biri olan Başkomutan Meydan Muharebesi (30 Ağustos 1922), Dumlupınar’da yapılmıştır. Bugün araştırma sahasında bulunan anıt, abide ve şehitlikler bu zaferin izlerini taşımaktadır.
Genel olarak tarım faaliyetlerinin önem kazandığı sahada tarım ve hayvancılık dışındaki ekonomik faaliyetler pek gelişememiştir. Bu durum, sahanın fiziki coğrafya özelliklerinin yanında yetersiz yatırım koşullarından da kaynaklanmaktadır.Altintaş Creek Watershed and most of its environs that are study area are located at the Aegean Region’s inner west Anatolia's sub-region. Also this site is in the border of the Afyonkarahisar, Kutahya, Usak and Eskisehir provinces.
Kocadag Mount (1.552 m) and Kulaksiz Mount (1.588 m) located at the north of the study area. The study area is surrounded with Kartal Mount (1.442 m) from the southern part, Tava Mount from the western part and Kalankaya Mount (1.361 m). Altintas River Watershed separated from the Banaz Creek Watershed at the south, Porsuk Creek Watershed at the north, from Seydiler Creek Watershed at the east and Akarcay Creek Closed Watershed at the south-eastern.
In the study area; the Paleozoic era aged sites are at the south (Afyon-Ihsaniye environs), Mesozoic era aged sites at the western part of the Kutahya and on the Kutahya-Afyon highway environs are lying at the surface. Common geological units of the study area are consisted of Pliocene and Miocene aged latchstring and volcanic rocks. Common rock types are limestone and volcanic rock units. Alluvial material covers plains.
There is no important altitude difference between Mountain masses that is located and surrounded at the study area. The most important height is located at the Murat Mount (2309). Altıntaş and Aslanapa Plains are watered by Altintas River and these plains are very important agriculture sites.
The climate of the Altintas River Watershed and its environs are different from the Mediterranean climate and very close to continental climate. Hence, it is sunny, no precipitation and warm at the summer season. Therefore drought is in effect in this region. Even so, the temperature decreases and pressure increases from October. Mean annual temperature is 10.6 °C and mean annual precipitation is 430 mm.
The network of creeks is consisted of Altintas River and its branches. These creeks waters the Altintas and Aslanapa Plains.
The study area is a temporary or permanent site for the communities (settlements). In this area, the oldest and the most important civilization were established by Phrygians. For this reason, this region was called “Phrygia” in this period. The kingdoms of Kimmer, Persians, Ionians, Romans and Byzantine were lived here. Tumuli and walled tombs that remain from these ancient times were found in the Altintas town/province.
Kütahya has been a province centre since the 9th October 1923; Altıntaş has been a county since 1947. This county is consisted of 5 quarters, 2 communities and 33 villages. Altintaş's population is 25.262 inhabitants. 6.418 of them are living in the county centre (town), 2287 of them are living in the Çayırbaşı community, 2.449 of them are living in the Zafertepeçalköy community and 14.108 of them are living in the villages.
Head Commandant Major Battle that is one of the main battles of Turkish Liberation (Independence) War had occurred 30th August 1922 in Dumlupınar. There are memorials, monuments and martyr graveyards from this battle and victory.
The most important economic activities are agriculture and animal breeding, but the other activities are not developed in this area. The reasons of this are physical geographic conditions and also inadequate business circumstances
Development of a Novel MultiBody Mechatronic Model for Five-Axis CNC Machine Tool
No full textThe paper presents the development of a mechatronic hybrid model for Geiss five-axis CNC machine tool using MultiBody-System (MBS) approach. The motion control systems comprising electrical and mechanical elements are analyzed and modeled. The 3D assembly of the machine tool is built in SolidWorks and exported into SimMechanics which interfaces seamlessly with SimPowerSystems, SimDriveline, and Simulink packages. CNC machine tools are mechatronic systems incorporating non-linearities so the proposed multibody mechatronic model (which considers the coupling of elastic mechanical structures with the control systems) represents accurately the dynamic behaviour of the actual machine by using only one simulation environment
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
Integral-Equation Study of Ray Effects and Natural-Mode Resonances in a 2-D Dielectric Prism
No full textAltintas, Ayhan/0000-0002-3501-4010We analyze the interplay of two different types of electromagnetic behavior demonstrated by a 2-D dielectric prism: Geometrical Optics and resonance. As it is shown, the first is responsible, for instance, for enhanced reflection from an isosceles 90-degree prism of arbitrary epsilon and size, if illuminated from the base. The second is responsible for the peaks in the total scattering and absorption cross-sections (RCS) at the natural-mode frequencies. The numerical model is based on Nystrom discretization of Muller-type integral equations that provides guarantied convergence
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