177 research outputs found
Static and dynamic properties of CN/Cu(001) surfaces and oxidation, dissociation and bimolecular debarboxylation of isocyanate species adsorbed on Cu(001)
No full textThis dissertation presents an outlines my investigations of static and dynamic properties of adsorbed cyanide (CN) and isocyanate (-NCO) species as well as some of their chemistries. Surface bound CN-containing species have not previously been studied extensively, partially due to the inapplicability of fundamental e-beam based surface analysis techniques for investigations. I had the opportunity in my studies to employ multiple surface probing techniques, i.e. HAS, XPS, NEXAFS, TPD and RAIRS, to compile and cross-examine information from CN, –NCO, and derived species, adsorbed on the Cu(001) surface. While angle resolved He atom scattering (HAS) was employed to identify and investigate the ordered superstructure of CN/Cu(001) surfaces, TOF-HAS was employed to investigate its dynamic properties. The CN/Cu(001) surface induced unprecedented simultaneous coherent He diffraction with a large “classical” multiphonon backscattered He intensity. A superstructure is implied that contains both rigidly bound CN species, which maintain the long range c(10x6) translational symmetry, together with bound highly-dynamic CN species that exhibit large thermally induced displacements. The NEXAFS measurements suggest multiple spatial binding configurations for the adsorbed CN moieties. In addition, TPD spectra of C2N2 desorption from CN/Cu(001) surface were analyzed, using my newly developed method, to determine the activation energies for desorption as a function of CN coverage. There are two reactions of NCO species examined in my studies. The first is the newly discovered mutual reaction between NCO species. This type of interaction had not been seen before, as it is essentially difficult to prepare pure NCO/metallic surfaces. Copper was chosen as a substrate as HNCO exposures of Cu(001) at RT, followed by spontaneous H2 desorption, do produce NCO only surfaces. A thermal treatment of the surface, at 573K, leads to a bimolecular decarboxylation of NCO, leaving a carbodimide species (NCN) on the surface. The sp-hybridized linear NCN moieties, which are bound nearly parallel to the substrate, show high thermal stability. The second reaction of NCO, which I have studied, is its oxidation. In particular, the effect of CN coadsorbates on the oxidation of NCO was studied. It was found that the presence of CN catalyzes a dissociation reaction of NCO species on Cu(001).Ph. D.Includes bibliographical referencesby Erkan Ziya Ciftlikl
Effect of size and slenderness on the axial-compressive behavior of basalt FRP-confined predamaged concrete
No full textTo investigate the size and slenderness effect on the axial-compressive behavior of basalt fiber-reinforced polymer (BFRP)-confined predamaged concrete, five groups of concrete cylinders with different sizes and slenderness ratios were designed and tested. The cylinders were axially preloaded to three predamage levels, then repaired using BFRP, and reloaded. The results showed that the concrete predamage had an adverse effect on the ultimate strength and initial elastic modulus of BFRP-confined concrete. Except for the smallest specimens affected by the wall effect, the initial analysis found that the ultimate strength of BFRP-confined concrete decreased with an increase in size and slenderness ratio, and the size and slenderness effect decreased with an increase in BFRP confining pressure, while these increased with the severity of concrete predamage. However, there was no obvious size or slenderness effect on the ultimate strain of BFRP-confined concrete. Through multifactorial analysis, it was confirmed that the ultimate strength of BFRP-confined undamaged and predamaged concrete was influenced by the slenderness. Considering the effect of size, slenderness, and predamage, monotonic and cyclic models were developed for BFRP-confined concrete. Finally, a uniaxial material object was added into OpenSees to provide an effective numerical material model for theoretical analyses and engineering applications. © 2021 American Society of Civil Engineers.The present research was supported by the National Natural Science Foundation of China (Grant No. 51878268) and the Natural Science Foundation of Hunan Province, China (Grant No. 2020JJ4195).
Part of this research was completed by the first author in collaboration with the third and fourth authors during his one-year visit to Ohio State University. The first author acknowledges the State Scholarship Fund of China Scholarship Council (Grant No. 201606135057) for supporting this work and his research visit to the United States
A Comparison of the Ballistic Performances of Various Microstructures in Mil-A Armor Steel
No full textKonca, Erkan/0000-0001-8943-091XDue to their advantageous properties, there is a growing interest in developing armor steels containing fully or partially bainitic microstructures. In this study, bainitic and martensitic microstructures were obtained in rolled homogeneous armor (RHA) steel samples and their ballistic protection performances were investigated. RHA (MIL-A-12560) steel samples were subjected to isothermal heat treatments at three different temperatures, where one temperature (360 degrees C) was above the martensite formation start (Ms) temperature of 336 degrees C while the other two (320 degrees C and 270 degrees C) were below. For the assessment of the ballistic protection performance, the kinetic energy losses of the 12.7 mm bullets fired at the test samples were determined. The promising nature of the bainite microstructure was confirmed as the sample isothermally treated at 360 degrees C provided approximately 10% higher ballistic protection as compared to the regular RHA sample of tempered martensite microstructure. However, the ballistic performances of the isothermally treated samples decreased as the treatment temperature went below the Ms temperature. Following the ballistic tests, hardness measurements, impact tests at -40 degrees C, and macro- and microstructural examinations of the samples were performed. No correlation was found between the hardness and impact energies of the samples and their ballistic performances.ROKETSAN Missile Industries Inc. (Ankara, Turkey)This research was funded by ROKETSAN Missile Industries Inc. (Ankara, Turkey). The APC was paid for by the author
A statistical design optimization study of a multi-chamber reactive type silencer using simplex centroid mixture design
No full textArslan, Hakan/0000-0002-2019-1882This study aims to optimize the acoustic performance of a silencer with baffles having extension tubes. It considers the position, the number and the extension geometry of the baffles as design variables and sound transmission loss as the response variable to be optimized. The finite element analysis software ABAQUS is used to compute the response values for different combinations of design variables. The statistical design of the experiments provides a mathematical framework for such computer design optimization studies with multiple design variables. Yet, it has not been used for design optimization of silencers in the literature. In this study, simplex centroid mixture designs, a type of response surface method, are used in the statistical design of experiments. They can provide faster convergence on the optimization problem. The design involves one, two and three baffles with different positions and extension tube lengths. The outcome of this study indicates that obtaining ABAQUS software solutions at design points for each baffle number allows constructing nonlinear regression equations expressing the response variable as a function of the design variables. The equations obtained are then used to compute optimal values. Further evaluation of these equations indicates that better sound transmission loss values are obtained when the baffle number is increased, and the lengths of the extension tubes are set at high values. Moreover, it is possible to use the statistical experimental design approach implemented in this study for other types of silencers with different baffle geometries and design variables
Vocabulary in poet-author Nuri Pakdil in the works of the essasy type
No full textSosyal Bilimler Enstitüsü, Türk Dili ve Edebiyatı Ana Bilim Dalı, Yeni Türk Dili Bilim DalıDilimizdeki sözcüklere cümle içinde kullanım şekline göre çok çeşitli anlamlar yüklenebilmektedir. Bu nedenle bir dildeki sözcüklerin sayısının tespiti kadar kelimelerin çok anlamlılığının tespiti de o dilin zenginliğini ortaya koymada gereklidir. Kelimeleri işleyen, onlara yeni anlatım olanakları sağlayanlar ise şair ve yazarlardır. Nuri Pakdil, kendine has üslubu ve sözcük tercihleriyle oldukça dikkate değer bir yazardır. Hakkında yazılı ve görsel alanda pek çok çalışma yapılmakla birlikte eserleri üzerine söz varlığı açısından bir çalışma yapılmamıştır. Çalışmada Nuri Pakdil'in deneme türündeki eserlerinde yer alan söz varlığının ortaya koyulması amaçlanmıştır. Eserlerin bir bölümü deneme/günlük tarzında olduğundan yazarın yaşamına ait bilgiler de içermektedir. Benzer şekilde eserlerin düşünce yazısı olması sebebiyle yazarın dünya görüşü ile edebî ve fikri eleştirileri de bu eserlerde görülmektedir. Yazarın hayatı, edebi şahsiyeti ve eserleri hakkında bilgi verildikten sonra sözcük ve söz varlığı kavramlarına değinilerek, incelenen eserlerde kullanılan dil, temel söz varlığı bağlamında değerlendirilmeye çalışılmıştır. Çalışmada, eserlerdeki kelimelerin kullanım sıklıklarının tasnifi yapılmıştır. Ayrıca incelenen eserlerin dizinleri de toplu olarak çalışmada yer almaktadır.ABSTRACT The words in our language can be loaded with a variety of meanings according to the usage in the sentence. For this reason, the determination of the number of words in a language as well as the determination of the meaning of words is necessary to reveal the richness of the language. Poet sand writers are the ones who process the word sand provide them with new narrative opportunities. Nuri Pakdil is a remarkable writer with her uniquestyle and vocabulary choices. Although there are many written and visual studies about it, there has not been any study in his vocabulary. Nuri Pakdil, who is a very important man of ideas besides the writer-poet-translatoridentity, is very interesting. In our study, it was a imed to reveal the vocabulary of Nuri Pakdil in his essay types. Since some of the worksare in a trial / daystyle, they also contain information about the life of the author. Similarly, the author's world view and his literary and intellectual criticism can be seen due to the fact that the worksare thought texts. After informing the author about the word and vocabulary in the general framework, the language used in the works examined has been tried to be evaluated in the context of the basic vocabulary. The frequency of use of the words in the Works were classified. In addition, the directories of the studied works are also included in our study
Theoretical and experimental investigation of acoustic performance of multi-chamber reactive silencers
No full textArslan, Hakan/0000-0002-2019-1882; Ranjbar, Mostafa/0000-0002-9670-7371The acoustic attenuation and performance analysis for blast flow field inside a silencer is investigated. In this regard, a silencer system is designed to reduce the exhaust noise. The effect of position and the number of the baffles for each design on sound transmission loss have been investigated using theoretical, numerical and experimental studies. Three prototypes are manufactured for the experimental studies. Using the measured results, insertion loss graphics have been obtained. The silencer performances are dependent on the baffle geometry, number and the positions. The experimental results are in a good agreement with the simulation results. It is observed that by considering the same number of baffle numbers but located at various locations, the model which shows the best sound transmission loss performance has also the best insertion loss performance and has the least value of peak sound pressure level. (C) 2019 Elsevier Ltd. All rights reserved.Mechanical and Chemical Industry Corporation of Turkey; Turkish Ministry of Science, Industry and TechnologyMinistry of Science, Industry & Technology - TurkeyThe authors want to express their appreciation to Mechanical and Chemical Industry Corporation of Turkey and the Turkish Ministry of Science, Industry and Technology for their support in this work
An author report: Elfreda Annmary Chatman
No full textThe main aim of this report is to become familiar with Elfreda A. Chatman and her major works and theories. She has contributed information science by producing several theories such as “the theory of information poverty,” “the normative behavior theory” and “the theory of life in the round” and implemented many studies about information seeking behavior of ordinary people. Although her major is library and information science, she focused on women in prison, the feminist movement, poor workers and janitors at large universities by using an ethnographic perception. She emphasized their information seeking behaviors in small communities and tried to describe their approach about information poverty. Also, she studied public libraries and the role of mentorship of the library leaders. The findings she found in her studies are useful not only for information science but also other disciplines such as sociology and psychology
European option pricing under the rough Heston model using the COS method
No full textThis thesis is about pricing European options using a Fourier-based numerical method called the COS method under the rough Heston model. Besides examining the efficiency and accuracy of the COS method for pricing options under the rough Heston model, it is also investigated if the rough Heston model produces the advantages of the so-called rough volatility models. To do so, the characteristic function of the rough Heston model is derived, and the COS method for the rough Heston model and also a Monte Carlo simulation scheme is introduced. Throughout the thesis, the theoretical background of the rough Heston model, the numerical techniques and some numerical experiments on European option prices and implied volatility behaviors are presented. Also, a calibration of the rough Heston model is performed using Artificial Neural Networks. As a result of this thesis, pricing of European options using COS method is succeeded. Moreover, it is shown that the rough Heston model produces the rough volatility behaviors as expected.Applied Mathematic
Technical and thematic analysis of Najib El Kilani's Heroes of the North
No full textNecîb el-Kîlânî, Mısır edebiyatının önemli temsilcilerinden biridir. Eserlerinde, İslami konuları merkeze alan yazar, sadece Arap Yarımadasındaki Müslümanların sorunlarını işlememiş, aynı zamanda dünyanın çeşitli bölgelerindeki Müslümanların da mücadelesini ele almıştır. Kuzey Kahramanları da Nijerya'da yaşayan Müslümanların mücadelesini ele almıştır. Çalışmamızda eserin teknik ve tematik açıdan incelenmesine yer verilmiştir. Eser, kahramanlık, aşk, savaş ve işkence gibi temaları tarihi bağlamda ele almıştır. Yazarın kullandığı dil ve üslup özellikleri, anlatım teknikleri ve karakter tasvirleri ayrıntılı bir şekilde incelenmiştir. Yazar, eserinde etkileyici anlatım tarzı ve kullandığı sade dil sayesinde okuyucunun olay örgüsü içine girmesini sağlamıştır.Najib al-Kilani is one of the important representatives of Egyptian literature. In his works, the author, who centred on Islamic issues, not only dealt with the problems of Muslims in the Arabian Peninsula, but also the struggle of Muslims in various parts of the world. Heroes of the North also deals with the struggle of Muslims living in Nigeria. In our study, the work is analysed in technical and thematic terms. The work deals with themes such as freedom, heroism and love in a historical context. The language and stylistic features, narrative techniques and character descriptions used by the author were analysed in detail. The author has enabled the reader to enter into the plot thanks to his impressive narrative style and simple language
Endocan levels and subclinical atherosclerosis in patients with systemic lupus erythematosus
No full textCure, Medine Cumhur/0000-0001-9253-6459; Mikhailidis, Dimitri/0000-0002-9566-2263; cure, erkan/0000-0001-7807-135X; Balta, Sevket/0000-0002-6657-7334Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of unknown etiology. A major cause of morbidity and mortality in SLE is accelerated atherosclerosis. Endothelial-specific molecule 1 (endocan) is a potential predictor of vascular events and is expressed in response to inflammatory cytokines in endothelial cells. We investigated the relationship between endocan and carotid intima-media thickness (cIMT) as a marker of early atherosclerosis. We included 44 women with SLE and 44 healthy women as controls. Disease severity of SLE was evaluated using the SLE Disease Activity Index. Endocan, C-reactive protein, erythrocyte sedimentation rate (ESR), and lipid panel were measured. the cIMT was 0.70 (range: 0.45-1.20) mm in patients with SLE and 0.40 (0.25-0.60) mm in controls (P < .001). Endocan value was 1.6 +/- 0.9 ng/mL in controls and 2.2 +/- 1.0 ng/mL in patients with SLE (P = .014). Endocan levels were positively correlated with cIMT (r = .469, P < .001), body mass index (r = .373, P = .013), and ESR (r = .393, P = .008). Endocan level may be associated with subclinical atherosclerosis in SLE. Consequently, endocan levels may be a promising clinical tool for patients with SLE as a guide for preventive strategy.MSD; AstraZenecaAstraZeneca; LibytecThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: DPM has given talks and attended conferences sponsored by MSD, AstraZeneca and Libytec
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