Subsonic Flutter of Cantilever Rectangular PC Plate Structure

Flutter characteristics of cantilever rectangular flexible plate structure under incompressible flow regime are investigated by comparing the results of commercial flutter analysis program ZAERO© with wind tunnel tests conducted in Ankara Wind Tunnel (ART). A rectangular polycarbonate (PC) plate, 5 × 125 × 1000 mm in dimension, is used for both numerical and experimental investigations. Analysis and test results are very compatible with each other. A comparison between two different solution methods (g-method and k-method) of ZAERO© is also done. It is seen that the k-method gives a closer result than the other one. However, g-method results are on a conservative side and it is better to use conservative results, namely, g-method results. Even if the modal analysis results are used for the flutter analysis for this simple structure, a modal test should be conducted in order to validate the modal analysis results to have accurate flutter analysis results for more complicated structures

The impact of the iron and steel industry to Karabuk and Sheffield : a historical background

In this study, the two cities, Sheffield in the UK and Karabük in Turkey, which are famous for iron and steel producing, were analyzed through their historical background to focus on the differences and similarities from an urban perspective. Both the rise in the production of iron and steel in the 18th century through Industrial Revolution and the innovations made Sheffield popular throughout the world. Karabük is called “The Republic City” in Turkey because the first iron and steel works were built in Karabük in 1937 shortly after the proclamation of Republic of Turkey. The museums were visited and the local studies and academic papers were sorted out to see the effects of sudden changes which the heavy industry caused in the cities and it’s concluded that the industrial, urban and social experiences of Sheffield may be a guide for Karabük.peer-reviewe

Serum ghrelin levels in inflammatory bowel disease with relation to disease activity and nutritional status

Ghrelin possesses various biological activities-it stimulates growth hormone (GH) release, plays a major role in energy metabolism, and is one of the hormones that affects body composition. It also plays a role in modulating immune response and inflammatory processes. In this study we aimed to determine whether serum ghrelin levels had correlation with markers associated with disease activation. We also investigated any probable relationship between serum ghrelin level and nutritional status. Serum levels of ghrelin and its relationship with disease activity and nutritional status were evaluated in 34 patients with ulcerative colitis (UC), 25 patients with Crohn's disease (CD), and 30 healthy controls. Serum ghrelin levels, serum IGF-1 and GH levels, and markers of disease activity (sedimentation, C-reactive protein, and fibrinogen) were measured in all subjects. Body composition and nutritional status was assessed by both direct (by anthropometry) and indirect (by bioimpedance) methods. Serum ghrelin levels were significantly higher in patients with active UC and CD than in those in remission (108 +/- 11 pg/ml vs. 71 +/- 13 pg/ml for UC patients, P < 0.001; 110 +/- 10 pg/ml vs. 75 +/- 15 pg/ml for CD patients, P < 0.001). Circulating ghrelin levels in UC and CD patients were positively correlated with sedimentation fibrinogen and CRP and was negatively correlated with IGF-1, BMI, TSFT, MAC, fat mass (%), and fat free mass (%). This study demonstrates that patients with active IBD have higher serum ghrelin levels than patients in remission and high levels of circulating ghrelin correlate with the severity of disease and the activity markers. Ghrelin levels in inflammatory bowel disease (IBD) patients show an appositive correlation with IGF-1 and bioelectrical impedance analysis, body composition, and anthropometric assessments. Finally, we arrived at the conclusion that ghrelin level may be important in determination of the activity in IBD patients and evaluation of nutritional status

Comparative analysis of Istanbul And Hamburg metropolitan management models

Dünyada metropoliten yönetim alanı uygulamaları nüfusun ve sanayileşmenin artmasıyla birlikte önem kazanmıştır. Bu nedenle iyi bir yönetişimin sisteminin gerçekleştirilebilmesi amacıyla gerek dünyada gerekse Türkiye'de iyi uygulamaların belirlenmesi gerekmektedir. Bu bağlamda iyi metropoliten uygulamalarının yaygınlaşması için karşılaştırmalı araştırmaların yapılması önem arz etmektedir. Bu çalışmada, İstanbul ve Hamburg metropoliten alanları ekonomik ve demografik kriterler yanında başkan seçim yöntemi ve görev süresi, ilçe sayıları, metropoliten yönetim modeli vb. gibi değişkenler açısından karşılaştırılmıştır. Sonuçta; nüfusu ve bulunduğu bölge açısından her iki kentte de ortak ve faklı noktalar bulunduğu, belediye başkanı Hamburg’da belediye meclis üyelerince, İstanbul’da ise doğrudan halk tarafından seçildiği, İstanbul’un 1984, Hamburg’un ise 2012 yılında metropoliten alan olduğu, İstanbul merkezi bütçeden %6 pay alırken Hamburg’un %15,5 pay aldığı tespit edilmiştir. Her iki şehirdeki metropoliten alanın yönetim biçiminin iki kademeli sistemi olması aralarındaki benzer özelliklerden biridir.In the world, the metropolitan administration applications have gained importance due to increasing population and industrialization. Therefore; both in the world and Turkey, successful applications are required to be specified in order to realise a successful administration system. In this context, it is important to make comparative researches to spread the successful metropolitan applications. In this study, Istanbul and Hamburg metropolitan areas have been compared in terms of not only economical and demographic criterias but also the criterias such as mayor’s selection method and its term of office, district numbers, metropolitan management model, etc. As a result, in terms of their populations and the regions that they are located into, these have been founded that both cities have common and different features. The mayor is selected by municipality assembly members in Hamburg while s/he is selected directly by the community in Istanbul. Istanbul became metropolitan area in 1984 andn Hamburg in 2012. Istanbul takes %6 share from the budget while Hamburg takes %15,5 share. One of the common features between them is that the metropolitan area administration system in both cities is a two-stage syste

Die Auswahl Der Richtigen E-Commerce-Software Für Das Eigene Unternehmen - Anwendung Des AHP-Modells(Şirketiniz İçin Doğru E-Ticaret Yazılım Seçimi – AHP-Model Uygulaması)

Die Auswahl der richtigen eBusiness-Software-Lösung hat für das eBusiness-Geschäft von Unternehmen eine große Bedeutung. Das bedeutet, dass die Unternehmen eines kompetentes, effizientes, flexibles und starkes Softwarepakets bedürfen. Dafür müssen sie eine ausführliche Analyse des passenden Softwarepaketes aus dem wirtschaftlichen Aspekt ausführen. Denn eine solche Softwarelösung soll einem Unternehmen ermöglichen, ihre Produkte und Dienstleistungen problemlos online anbieten zu können. Es wird festgestellt, dass sie Auswahl solcher Softwarepakete sorgfältig durchgeführt werden müssen, da diese unterschiedliche Stärken bzw. Eigenschaften aufweisen. Zum Beispiel hat eine Lösung sehr gute Marketing-Tools, die andere jedoch Sicherheits- oder Flexibilität-Tools. Im ersten Teil der Arbeit wird auf die Bedeutung der Auswahl einer eBusiness-Lösung eingegangen und es werden dabei die relevanten Eigenschaften von Softwarelösungen sowie ihre Relevanz für den Unternehmensgeschäftserfolg geschildert. Im zweiten Teil wird der Analytic Hierarchy Process dargestellt, bei dem das Entscheidungsproblem in kleinere Teilaufgaben aufgelöst werden, die dann zu lösen sind. Schließlich werden im dritten Teil in einer abschließenden Zusammenfassung die Ergebnisse und die Schlussfolgerungen geschildert

EXPERIMENTAL AND THEORETICAL INVESTIGATION OF MACHINING WITH CONDUCTIVE POWDER REINFORCED POLYMER MATRIX COMPOSITE ELECTRODE IN ELECTRIC DISCHARGE MACHINING

Bu çalışmanın amacı, elektroerozyon ile işlemede (EEİ) elektrot üretilebilirliğini kolaylaştırmak ve maliyetini düşürmek için, alternatif bir elektrot üretim yöntemi geliştirmektir. Bu amaç için, elde hazır halde bulunan modelden alçı, silikon, reçine v.b. bir kalıp yapılarak, daha önce hazırlanmış tutucu ve iletken dolgu malzemesinden oluşan karışımın bu kalıp içine dökülmesi ve katılaşması sağlanmıştır. Çalışmada, tutucu malzeme olarak polyester reçine ve iletkenliği sağlaması için dolgu malzemesi olarak dendritik şekilli saf bakır tozu, grafit tozu ve bunların karışımı kullanılmıştır. Karışımın, döküldüğü kalıpta kısa sürede sertleşerek rijit hale gelmesi için, hızlandırıcı ve dondurucu olmak üzere iki farklı kimyasal madde kullanılmıştır. İş parçası işleme (İİH) ve elektrot aşınma hızlarını (EAH) karşılaştırarak en uygun elektrot tipini belirlemek amacıyla, serbest bakır-polyester (NB/ P), sıkıştırılmış bakır-polyester (S-B/P), pişirilmiş bakır-polyester (PB/ P), pişirilmiş bakır-grafit-polyester (P-B/G/P) ve sıkıştırılmış bakırgrafit- polyester (S-B/G/P) olmak üzere beş farklı tip kompozit elektrot üretilmiştir. İşleme sonrası İİH, EAH ve bağıl aşınma (BA) değişimleri her tip elektrot için grafik halinde gösterilmiştir. v Elektrotların (N-B/P, S-B/P ve P-B/P tipleri için) elektriksel karakteristiklerini çıkarmak için, işlemede kullanılmış elektrotlardan disk şeklinde numuneler hazırlanarak elektriksel dirençleri ölçülmüş; bu veriler kullanılarak elektrotların elektriksel iletkenlikleri hesaplanmıştır. Elektrotların eşik (perkolasyon) konsantrasyonları, eşik iletkenlikleri, doyma sınırları ve şekil faktörleri karakteristik iletkenlik-konsantrasyon denklemleri ile gösterilmiştir. Çalışmada, pratik uygulamaya en uygun olan P-B/P kompozit elektrotların performansının dolgu malzemesi tane boyutu ile olan ilişkisi incelenmiştir. Ayrıca, kompozit elektrotların İİH ve EAH karakteristiklerinin, dolgu malzemesi konsantrasyonu ve tane boyutu ile olan ilişkileri matematiksel denklemler olarak türetilmiştir. Bu çalışma, tutucu malzeme olarak ortoflatik polyester ve dolgu malzemesi olarak bakır tozundan üretilen kompozit elektrotun EEİ'ye uygulaması olarak bir ilktir.The aim of this study is to develop an alternative electrode production method in order to make the electrode producibility easier and decrease the cost in electric discharge machining (EDM). For this purpose, after constructing a mould made of plaster, silicon or resin using the available model, it is attempted to spill the mixture composed of the matrix and conductive filler into this mould and to solidify it. In this study, polyester resin is chosen as the matrix and the dendriticshaped pure copper powder, graphite powder, and their mixture are used as the filler in order to provide the conductivity. In order for the mixture to take a hardened rigid form in its mould in a short duration, two different chemical substances, namely, an accelerator and a freezer, are used. In order to decide on the most convenient electrode type by comparing the material removal rate (MRR) and tool wear rate (TWR), five diferent types of electrodes, namely, free copper-polyester (N-B/P), compressed copper-polyester (S-B/P), sintered copper-polyester (P-B/P), compressed copper-graphite-polyester (S-B/G/P), and sintered coppergraphite- polyester (P-B/G/P) are produced. After the machining vii process, İİH, EAH, and relative wear (RW) values are graphically demonstrated for each type of electrode. To find out the electrical characteristics of the N-B/P, S-B/P, and P-B/P type electrodes, their electrical resistances are measured by preparing disc shape samples from the ones used in machining and their electrical conductivity values are determined using these data. Afterwards, the percolation concentration, percolation conductivity, saturation limits, and form factor values of the electrodes are obtained by means of the characteristic conductivity-concentration equations. In the study, the relationship of the performance of P-B/P composite electrodes which are the most convenient ones for pratical application with the grain size is examined. Furthermore, the relationships of the MRR and TWR characteristics of the composite electrodes with the concentration and grain size of the filler are derived as mathematical equations. This is the unique study as applying of composite electrode produced by the ortoflatic polyester as matrix and dendritic shape pure copper powder as filler to EDM