5342 results
Search Results
Now showing 1 - 10 of 5342
Article Citation - WoS: 29Citation - Scopus: 38An Experimental Study of Cutting Performances of Worn Picks(Springer Wien, 2016) Dogruoz, Cihan; Bolukbasi, Naci; Rostami, Jamal; Acar, CemilThe best means to assess rock cuttability and efficiency of cutting process for using mechanical excavation is specific energy (SE), measured in full-scale rock cutting test. This is especially true for the application of roadheaders, often fitted with drag-type cutting tools. Radial picks or drag bits are changed during the operation as they reach a certain amount of wear and become blunt. In this study, full-scale cutting tests in different sedimentary rock types with bits having various degree of wear were used to evaluate the influence of bit wear on cutting forces and specific energy. The relationship between the amount of wear as represented by the size of the wear flats at the tip of the bit, and cutting forces as well as specific energy was examined. The influence of various rock properties such as mineral content, uniaxial compressive strength, tensile strength, indentation index, shore hardness, Schmidt hammer hardness, and density with required SE of cutting using different levels of tool wear was also studied. The preliminary analysis of the data shows that the mean cutting forces increase 2-3 times and SE by 4-5 times when cutting with 4 mm wear flat as compared to cutting with new or sharp wedge shape bits. The grain size distribution of the muck for cutting different rock types and different level of bit wear was analyzed and discussed. The best fit prediction models for SE based on statistical analysis of laboratory test results are introduced. The model can be used for estimating the performance of mechanical excavators using radial tools, especially roadheaders, continuous miners and longwall drum shearers.Article Citation - WoS: 24Citation - Scopus: 30Dynamic Assessment of Multi-State Systems Using Phase-Type Modeling(Elsevier Sci Ltd, 2015) Eryilmaz, SerkanMulti-state systems have attracted great attention due to their wide applications in engineering. They have been effectively used in modeling various systems such as power supply systems and transportation systems. In this paper, phase type modeling is proposed for dynamic assessment of nonrepairable multi-state systems when the system degrades According to a Markov process. The utility of phase type modeling is demonstrated in the computation of mean lifetimes, mean residual lifetimes, and derivation of survival functions of series and parallel systems. A stochastic comparison result between two systems is also obtained using phase representations of survival functions. Extensive numerical results are presented to illustrate the applicability of the approach. (C) 2015 Elsevier Ltd. All rights reserved.Article Demokrasi ve İnsan Doğası(Bilim ve Teknoloji, 2014) Selçuk, Fatma ÜlküTarihin farklı dönemlerinde oy verme ve yönetme konusunda yetki sınırlaması olmuştur. Bu sınırlama, sınıfsal farklılıklardan kaynaklanabileceği gibi, cinsiyet farklılığından veya etnik farklılıklardan da kaynaklanabilmiştir. Ayrıca, akıl sahibi olma, siyasetle uğraşacak yeterli boş zamanı olma, temel eğitim almış olma gibi ölçütlerin de gündeme getirildiği görülmüştür. Günümüzde ayrıntılarda farklılıklar görülse de (örneğin hükümlülüğe, askerliğe dair düzenlemeler kısıtlamalar getirebilmektedir) pek çok ülkede reşit, kendi kararını verebilecek ehliyete sahip yurttaşlar, seçme hakkına sahiptir. Bu yazıda, seçme, oy verme, seçilme ve yönetme haklarına dair ehliyet konusu, kişilik bozuklukları çerçevesinde tartışılacaktır. Zira günümüzde, kişilik bozuklukları, akıl hastalığı statüsünde sayılmayıp bu bozukluklardan muzdarip olanlar genelde cezai ehliyeti haiz bireyler olarak değerlendirilir. Halbuki, yönetim konumlarında bulunan insanlar, başkalarının kaderini etkileyecek kararlar vermektedir. Bu kararlar, yaşamsal öneme de sahip olabilmektedir.Article Citation - WoS: 20Citation - Scopus: 20Properties of the Pc(4312) pentaquark and its bottom partner(Iop Publishing Ltd, 2021) Azizi, K.; Sarac, Y.; Sundu, H.We present an analysis of the newly observed pentaquark P-c(4312)(+) to shed light on its quantum numbers. To do that, the QCD sum rules approach is used. The measured mass of this particle is close to the Sigma D-++(c)- threshold and has a small width, which supports the possibility of its being a molecular state. We consider an interpolating current in a molecular form and analyze both the positive and negative parity states with spin-. We also consider the bottom counterpart of the state with similar molecular form. Our mass result for the charm pentaquark state supports that the quantum numbers of the observed state are consistent with J(P) = 1/2(-).Article Citation - WoS: 4Citation - Scopus: 4An Integrated Economy-Demography Model Reframed in a System Dynamics Setting(Wiley, 2019) Dural-Selcuk, Gozdem; Tunc, Huseyin; Tarim, S. ArmaganIn recent history, there has been an increasing concern about population aging and the associated increased economic burden in terms of high health-care expenses and pension payments. The need for decision support tools that can explore population dynamics has become a prominent issue. This study presents a comprehensive framework where one can scrutinize the key demographic drives of fertility (Total Fertility Rate/Age-Specific Fertility Rate) over macroeconomic indicators (technology, education, human capital) under exogenous mortality. The integrated model in this article is developed based on a reformulation of the unified growth theory. In the reformulated model, namely the "economy-demography model," the population age/sex structure is preserved, age-specific mortality is included, and fertility is measured in conventional demographic terms. The model is then presented in system dynamics framework, and its practical use is showcased with data obtained from the Turkish Statistical Institute. Copyright (c) 2020 System Dynamics SocietyArticle Citation - WoS: 11Citation - Scopus: 16Overcoming Environmental Challenges by Antagonizing Environmental Protesters: the Turkish Government Discourse Against Anti-Hydroelectric Power Plants Movements(Routledge Journals, Taylor & Francis Ltd, 2014) Ozen, HayriyeDue to the growing public importance of environmental concerns in the contemporary world, governments that prioritize economic interests over environmental concerns may try to counter environmental challenges not by openly declaring that they do not want to consider environmental demands, but by attempting to antagonize the protesters who voice such demands. This essay explores such a governmental response by analyzing the discourse articulated by the Turkish Government against movements that oppose the construction of hydroelectric power plants (HEPPs) on environmental grounds. In particular, the analysis focuses on how HEPPs, environmental claims and demands of movements, and environmental protesters are represented within the pro-HEPP discourse, and in what ways these representations appeal to popular perceptions. It is demonstrated that the discourse of the government attempts to counter the challenges of protesters by establishing an antagonist relation between the protesters and society by representing HEPPs as crucial for the economic development and, therefore, as compatible with the interests of society as a whole. Moreover, it also attempts to achieve this through portraying the protesters as criminals and terrorists who block the economic development of the country and pose significant threats to the commonwealth, not for legitimate environmental concerns but for some dubious motives and incentives. It is concluded that, with this approach, the government has managed to gain popular consent not only for the construction of HEPPs, but also for the repression of such movements.Article Citation - WoS: 32Citation - Scopus: 32Capacitance, Conductance, and Dielectric Characteristics of Al/Tio2< Diode(Springer, 2021) Gullu, H. H.; Yildiz, D. E.In this study, electrical properties of the Al/TiO2/p-Si diode structure with an atomic layer deposited TiO2 interface layer are investigated by current-voltage (I-V), capacitance-voltage (C - V), and conductance-voltage (G - V) measurements. It shows a rectifying behavior with about four order of rectification factor, and barrier height and ideality factor are calculated from the rectification curve. Dielectric parameters are determined from frequency-dependent C - V and G - V relations. The experimental results show that both of these curves are in a strong response to the frequency and bias voltage. They are found in decreasing behavior with increasing frequency, and both of them increase with increase in bias voltage although there are different increasing trends. At reversed bias voltage region, barrier potential, Fermi level energy, and interface charge carrier contribution are evaluated by using 1/C-2 - V plot. Series resistance values are also calculated under the variation of frequency and voltage. Thus, the capacitive characteristics of the diode are corrected by eliminating series resistance contribution together with the possible effect on interface charge carriers. Detailed information is obtained by determining electronic parameters affected by interface states over a wide frequency range (1 kHz to 1 MHz). At this point, strong response to the frequency is observed for the dielectric constant. Under the effect of interfacial polarization at low-frequency region, interface charge contribution to the capacitive response of the diode is obtained. Further analysis is performed on electrical modulus and impedance values derived from experimental dielectric data. Existence of interfacial layer capacitance is detailed by extracting distribution of interface charges from capacitance and conductance profiles of the diode under the effect of frequency.Article Citation - WoS: 1Citation - Scopus: 1An Empirical Analysis of the Average Plant Start-Up Size in Turkish Manufacturing Industries(Springer, 2012) Cilasun, Seyit Mumin; Gunalp, BurakMany studies have found start-up size of a firm to be an important determinant of its subsequent performance and probability of survival. The aim of this study is to investigate the determinants of average plant start-up size in 51 four-digit Turkish manufacturing industries for the period 1993-1999. The results of the study suggest that while industry characteristics such as industry growth rate and capital intensity have a positive impact on the average plant start-up size, industrial concentration, import penetration, and the change in research and development expenditures are negatively associated with the same variable. In addition, the macroeconomic environment is also an important determinant of the choice of plant start-up size. Finally, we find evidence that may indicate 'following' (herd) behavior in Turkish manufacturing industries.Article İHRACATÇI KOBİ’LER İÇİN BİR MODEL ÖNERİSİ: “BARTER”(Herkese Bilim Teknoloji, 2017) Saygılıoğlu, NevzatBarter; firmaların, bir ağ sistemi içerisinde, satın aldıkları mal ve hizmet karşılığında, para yerine, kendi ürettiği veya sattığı mal ve hizmetleri vermesidir. Yani nakit imkanlarının olmadığı durumlarda; firmaların, ürettiği mal ve hizmeti bir sisteme dahil etmesi ve sistemden de ihtiyacı olduğu mal ve hizmetleri satın almasıdır. Karşılıklı iki firma arasında değil, çok sayıda firma arasında yapılan bir reel ticaret biçimidir. Barter, kapalı devre bir sistem olarak sisteme dahil firmaların arasındaki alış veriştir. Ödeme şekli, yerli veya yabancı para yerine, satın aldığı mal veya hizmetlerin karşılığını kendi ürettiği veya alım satım konusu yaptığı mallarla karşılamaktır. Dolayısıyla iki firma arasında mallarının değiş tokuşunu ifade eden takas işleminden farklıdır.Article Citation - WoS: 6Citation - Scopus: 4Latent Dynamics of Movement Formation: the Kurdish Case in Turkey (1940s-1960s)(Sage Publications Ltd, 2015) Ozen, HayriyeThe attention of social movement studies has so far tended to focus on visible phases of movements, neglecting latent ones. This study argues that invisible mobilizations may be critical in preparing the groundwork of public mobilizations, particularly in authoritarian contexts. Using a process-oriented constructivist account of mobilization which incorporates insights from resistance studies, this article analyzes the Kurdish case in Turkey in the authoritarian 1940s and semi-authoritarian 1950s. Based on in-depth interviews, memoirs, newspaper reports, and official documents, it is demonstrated that a latent Kurdish dissent emerged in this period through the constitution of a sense of shared grievance and common identity both in hidden ways within the submerged networks of Kurdish students and professionals, and in public and visible, yet disguised, ways. Incubating the movement out of the gaze of the authorities within the authoritarian context, this latent dissent formed the groundwork of public acts of defiance and mobilization which emerged towards the end of the 1950s as the political changes encouraged Kurdish dissenters to publicly declare their opposition, and expanded in the more liberal context of the 1960s. Resume Les etudes des mouvements sociaux ont eu tendance jusqu'a present a privilegier les phases visibles de ces mouvements, negligeant les stades latents. Cette etude soutient que les mobilisations invisibles peuvent etre essentielles pour preparer le terrain des mobilisations publiques, en particulier dans un contexte autoritaire. En s'appuyant sur une interpretation constructiviste, axee sur le processus de mobilisation et reunissant des idees tirees des etudes des mouvements de resistance, cet article analyse le cas kurde dans la Turquie autoritaire des annees quarante et semi-autoritaire des annees cinquante. Fonde sur des entretiens approfondis, des biographies, des articles de journaux et des documents officiels, ce travail met en evidence l'apparition au cours de cette periode d'une dissidence kurde latente grace a la constitution d'un sentiment partage de mecontentement et d'identite commune au sein des reseaux secrets des etudiants et professionnels kurdes, de facon a la fois invisible et publique, mais dissimulee. Couvant a l'abri des regards des gouvernements autoritaires, cette dissidence latente a pose les bases des manifestations publiques de defiance et de mobilisation qui sont apparues a la fin des annees cinquante a l'occasion des changements politiques ayant encourage les dissidents kurdes a declarer publiquement leur opposition et favorise les mouvements sociaux dans le contexte plus liberal des annees soixante. Resumen La atencion de los estudios sobre movimientos sociales hasta ahora ha tendido a centrarse en las fases visibles de los movimientos, dejando de lado los latentes. Este estudio sostiene que las movilizaciones invisibles pueden ser centrales para la preparacion de las bases de movilizaciones publicas, en particular en contextos autoritarios. A partir de un relato constructivista orientado a los procesos de movilizacion que incorpora perspectivas de estudios de resistencia, este trabajo analiza el caso kurdo en Turquia en la decada autoritaria de 1940 y semi-autoritaria de 1950. Sobre la base de entrevistas en profundidad, memorias, informes de prensa y documentos oficiales, se demuestra que una disidencia kurda latente surgio en este periodo a traves de la constitucion de un sentimiento de agravio compartida y de identidad comun tanto en formas ocultas dentro de las redes sumergidas de estudiantes y profesionales kurdos, asi como de maneras publicos y visibles, aunque disfrazadas. Incubando el movimiento fuera de la mirada de las autoridades en el contexto autoritario, esta disidencia latente formo las bases del acto publico de rebeldia y movilizacion que surgio a finales de la decada de 1950 como los cambios politicos alentados disidentes kurdos para declarar publicamente su oposicion, y ampliado en el contexto mas liberal de la decada de 1960.
