Özkaya, Mert

Other | 2018 | Havacılık ve Uzay Teknolojileri Dergisi11 ( 2 ) , pp.119 - 133

In this paper, the existing 31 different UML-based software modelling languages have been analysed for anumber of requirements that are believed to be highly important for practitioners. These requirements areformal semantics, multiple viewpoints modelling, model analysis, code-generation, and modelling toolset.According to the analysis results, only the UWE, TTool, Pi-ADL languages support all those requirements. While21% of the languages offer general-purpose notation set, the rest offer domain-specific notation set and the topdomains of interest are the multi-agent, embedded, and real-time systems. 38% of the languages use UML’sp . . .rofiling mechanism for extending UML, 18% of the languages extend UML’s class diagram, and 13% of thelanguages extend UML’s state and sequence diagrams. 41% of the languages support the logical viewpoint and36% support the behaviour viewpoint – the rest of the viewpoints are rarely used. 58% of the languages aredefined formally and many of them are based on formal verification languages. 44% of the languages ignoremodel analysis. Among the rest, 25% of the languages support the exhaustive model checking and 14% supportthe analysis for well-formedness. Generating software code from software models and the modelling toolsupport are the least supported requirements by the UML-based languages. Bu makalede, mevcut 31 farklı UML-tabanlı yazılım modelleme dili yazılımcılar için önemli olan bir takımgereksinimler bakımından analiz edilmiştir. Bu gereksinimler, biçimsel semantik, çoklu bakış-açısı ilemodelleme, modellerin analizi, modellerden kod üretme, ve modelleme araçları desteği olarak belirlenmiştir.Analiz sonuçlarına göre, 31 farklı UML-tabanlı modelleme dili arasından sadece UWE, TTool, ve Pi-ADLdillerinin tüm belirtilen gereksinimleri karşılayabildiği gözlemlenmiştir. UML-tabanlı dillerin 21%’i genelamaçlı diller olarak belirlenmişken, geri kalanı ise alana özgü dillerdir ve en yaygın olan alanlar ise gömülüsistemler, çok etmenli sistemler, ve gerçek zamanlı sistemlerdir. UML-tabanlı dillerin 38%’i UML’in profilmekanizmasını kullanarak UML’i genişletirken, 18%’i UML’in sınıf diyagramını ve 13%’ü UML’in durum vesıra diyagramlarını genişletmektedirler. UML-tabanlı dillerin 41%’i mantıksal bakış açısını desteklerken,36%’sı da davranış bakış açısını desteklemektedir. Diğer bakış açıları (aynı anda kullanım, fiziksel, dağıtım, veoperasyonel gibi) pek destek görememektedir. UML-tabanlı dillerin 58%’inin semantiği biçimsel metotlarkullanılarak tanımlandığı belirlenmiştir. Dillerin 44%’ü modellerin analizini desteklememektedir. Geri kalanının25%’i ise kapsamlı model sınaması ile modellerin analizini desteklerken, 14%’ü ise dillerin biçim kurallarınagöre analizini desteklemektedirler. Yazılım modellerinin koda dönüştürülmesi hemen hemen hiçbir UML-tabanlıdil tarafından destek görmemektedir. Yine aynı şekilde, dillerin hemen hemen hiçbiri modelleme araçları iledesteklenmemektedir Daha fazlası Daha az

Utku, Feride Şermin | Özdemir, Ozan Enver | Bakay, Melahat Sevgül

Article | 2018 | Electrica18 ( 1 ) , pp.39 - 44

A molecularly imprinted polymer (MIP)-based impedimetric biosensor was developed for the electrochemical analysis of low-weight biological molecules. Synthetic polymeric matrices with specific and selective recognition sites, which are complementary to the shapes and sizes of the functional groups of analytes, can be prepared using the molecular imprinting method. In this study, a small molecule, tris(hydroxymethyl)aminomethane (TRIS), was used to coat a graphite pencil tip with a TRIS-containing polyacrylamide gel to fabricate a working electrode. The electrode modification and performance were evaluated using cyclic voltammetry an . . .d electrochemical impedance spectroscopy. The electrochemical properties of the modified electrodes were observed using an electrochemical cell comprising a Ag/AgCl reference electrode, a Pt wire as the counter electrode, and a pencil graphite tip as the working electrode using a redox-phosphate buffer solution with different concentrations of TRIS and Ethylenediaminetetraacetic acid (EDTA). The I–V and impedance performance of the chemically modified graphite pencil-tip electrodes exhibited decreased conductance and increased impedance correlating with the increase in TRIS concentration. Thus, MIP-based small-molecule biosensor prototypes can be promising economical replacements over other expensive sensors Daha fazlası Daha az

Şafak, Koray Kadir

Article | 2014 | Turkish Journal of Electrical Engineering and Computer Sciences22 ( 6 ) , pp.1611 - 1624

In this paper, methods to achieve actively powered walking on level ground using a simple 2-dimensional walking model (compass-gait walker) are explored. The walker consists of 2 massless legs connected at the hip joint, a point mass at the hip, and an infinitesimal point mass at the feet. The walker is actuated either by applying equal joint torques at the hip and ankle, by an impulse applied at the toe off, immediately before the heel strike, or by the combination of both. It is shown that actuating the walker by equal joint torques at the hip and ankle on level ground is equivalent to the dynamics of the passive walker on a downh . . .ill slope. The gait cycle for the simplified walker model is determined analytically for a given initial stance angle. Stability of the gait cycle by an analytical approximation to the Jacobian of the walking map is calculated. The results indicate that the short-period cycle always has an unstable eigenvalue, whereas stability of the long-period cycle depends on selection of the initial stance angle. The effect of the torso mass by adding a third link attached at the hip joint is investigated. The torso link is kept in the vertical position by controlling the torque applied to it. The proportional-derivative control law is utilized to regulate the angular position error of the torso link. Using linearized dynamics for this walker, active control is applied to the ankle, which reduces the dynamics of the walker to the passive walker without the torso. The proposed walker is capable of producing stable walking while keeping the torso in an upright positio Daha fazlası Daha az

Erdal, Cevat | Toker, Ali | Acar, Cevdet

Article | 2001 | Istanbul University Journal of Electrical and Electronics Engineering1 ( 2 ) , pp.267 - 273

Süreç kontrol endüstrisinde, orantı-türev-integral (PID) tip kontrolörler en önemli kontrol elemanlarından biridir. Uygulamada, analog kontrolörlerde genellikle işlemsel kuvvetlendiriciler kullanılmaktadır. Öte yandan ikinci nesil akım tasıyıcı ve akım geri beslemeli işlemsel kuvvetlendiriciler gibi akım çıkıslı olarak çalısan devreler, islemsel kuvvetlendiricilerle karşılaştırıldıklarında daha geniş bir frekans bandına, daha düşük güç tüketimi ile çalışma, ve daha iyi doğrusallık ve kararlılık özelliklerine sahip olduklarından, son zamanlarda oldukça çok dikkat çekmektedirler. Bu çalışmanın amacı akım tasıyıcılar (CCII) kullanarak . . .bir analog kontrolör gerçeklemek için gerekli tasarım yöntemini vermektir. Tasarımı yapılan PID devresi için optimum parametre toleransları hesaplanmıştır. Bu toleranslar önerilen PID kontrol edicinin duyarlık davranışlarının iyileştirilmesi ve kontrol edilmesinde kullanılabilirler. In process control industry, the proportional-integral-derivative (PID) controllers are one of the most important control elements. In practice, operational amplifiers are generally used in analog controllers. On the other hand, current-mode (CM) circuits such as second-generation current conveyors (CCII) and current feedback operational amplifiers (CFOA) have considerable attention due to their wider frequency band, lower power consumption, better linearity and stability properties compared to their voltage-mode counterparts, operational amplifiers. The purpose of this study is to present a synthesis procedure for the realization of analog PID controller by the use of CCIIs. For the designed PID circuit, the optimum parameter tolerances are determined. These tolerances can be used to improve and to control the sensitivity performance of the proposed PID controller Daha fazlası Daha az

Acar, Ebru Türköz | Onar, Atiye Nur

Article | 2016 | Turkish Journal of Chemistry40 ( 1 ) , pp.106 - 116

The electrochemical behavior of valproic acid (VAL) was investigated using square wave voltammetry, cyclicvoltammetry, and sampled direct current polarography and a new square wave voltammetric method was developed fordetermination of VAL in pharmaceutical preparations. VAL showed two reduction peaks at about {0.2 V and {0.8 V vs.Ag/AgCl 3 M KCl with a hanging mercury drop electrode in 0.05 M pH 3.3 Britton{Robinson (BR) buffer. These peakswere named peak I and peak II, respectively. The types of limiting current of both peaks were determined as diffusioncontrolled based on cyclic voltammetry studies. A linear calibration graph was . . .obtained in the range 1.46104{1.0103M. The limit of detection (LOD) and limit of quanti cation (LOQ) were 1.09104M (21.05g/mL) and1.10104M (144.20g/mL), respectively. Recovery studies for the accuracy of the method were performed byadding known amounts of VAL and it was found to be 109.674.85%. The proposed method was successfully appliedto pharmaceutical products on the market Daha fazlası Daha az

Atay, İrem | Kırmızıbekmez, Hasan | Yeşilada, Erdem | Gören, Ahmet Ceyhan

Other | 2015 | Turkish Journal of Chemistry39 ( 1 ) , pp.34 - 41

Abstract: A new nonglycosidic iridoid, sambulin B (1), was isolated from the methanol extract of Sambucus ebulus L. leaves along with a recently reported new nonglycosidic iridoid, 10-O-acetylpatrinoside aglycone (sambulin A) (2); 2 flavonoids, isorhamnetin-3-O-eta-D-glucopyranoside (3) and isorhamnetin-3-O-rutinoside (4); and a mixture of 2 flavonoids (5), quercetin-3-O-eta-D-glucopyranoside and quercetin-3-O-eta-D-galactopyranoside. Their structures were elucidated by 1-D and 2-D nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) experiments.

Kalay, Saban | Blanchet, Clement | Culha, Mustafa

Article | 2014 | Turkish Journal of Chemistry38 ( 5 ) , pp.686 - 700

The charge and size of molecules chemically attached to nanoparticles (NPs) play an important role in their interaction behavior in suspensions. Gold nanoparticles (AuNPs) were modified systematically with peptides and the modification was verified with surface-enhanced Raman scattering (SERS). The behavior of the modified AuNPs in suspension and at the liquidsolid interface was monitored using small angle X-ray scattering (SAXS), UV/Vis spectroscopy and dynamic light scattering (DLS) in suspension, and atomic force microscopy (AFM) at the solid liquid interface. It was found that while negatively charged peptide modified AuNPs beha . . .ve very similar to citrate reduced AuNPs due to their negatively charged surface, positively charged peptide modified AuNPs showed significantly different assembly/aggregation properties in suspension. The formation of linear assemblies of positively charged peptide (CKRHSKRHRSKRHSKRHSKRHSKR) modified AuNPs was clearly observed from the AFM analysis of the droplet areas of its colloidal suspension. The combined analyses of data obtained from the employed techniques suggest that the positively charged large peptide modified AuNPs can form linear and 3D-like networks in the suspension. This study reveals important information regarding the surface property dependent behavior of NPs that may help in efforts to build higher structures using NPs as building blocks Daha fazlası Daha az

Göker, İmran | Özkan, Mehmet

Article | 2004 | Istanbul University Journal of Electrical and Electronics Engineering4 ( 2 ) , pp.1171 - 1176

In this study,an electronic intra-oral artificial larynx system is designed. The objective of this study is to provide an alternative speech rehabilitation method to the totally-laryngectomized patients that will generate vibrations of fundamental frequency of human vocal cords. A prototype based on that design that is mounted into a dental prosthesis is established. The design of that system is presented in this paper.

Sak, Haşim | Güngör, Tunga | Safkan, Yaşar

Article | 2006 | Turkish Journal of Electrical Engineering and Computer Sciences14 ( 2 ) , pp.209 - 223

Speech synthesis is the process of converting written text into machine-generated synthetic speech. Concatenative speech synthesis systems form utterances by concatenating pre-recorded speech units. Corpus-based methods use a large inventory to select the units to be concatenated. In this paper, we design and develop an intelligible and natural sounding corpus-based concatenative speech synthesis system for the Turkish language. The implemented system contains a front-end comprised of text analysis, ,phonetic analysis, and optional use of transplanted prosody. The unit selection algorithm is based on commonly used Viterbi decoding a . . .lgorithm of the best-path in the network of the speech units using spectral discontinuity and prosodic mismatch objective cost measures. The back-end is the speech waveform generation based on the harmonic coding of speech and overlap-and-add mechanism. Harmonic coding enabled us to compress the unit inventory size by a factor of three. In this study, a Turkish phoneme set has been designed and a pronunciation lexicon for root words has been constructed. The importance of prosody in unit selection has been investigated by using transplanted prosody. A Turkish Diagnostic Rhyme Test (DRT) word list that can be used to evaluate the intelligibility of Turkish Text-to-Speech (TTS) systems has been compiled. Several experiments have been performed to evaluate the quality of the synthesized speech and we obtained 4-2 Mean Opinion Score (MOS) in the listening tests for our system, which is the first unit selection based system published for Turkish Daha fazlası Daha az

Keskin, Ali Ümit | Göker, İmran

Article | 2006 | Istanbul University Journal of Electrical and Electronics Engineering6 ( 1 ) , pp.113 - 115

One must first make sure that a given matrix subject to factorization is symmetric, and then use it in Cholesky algorithm, in MATLAB. This may cost machine time to check for symmetry, however, saves much more of it by preventing errors due to inherent structure of the built-in algorithm.

Yeğin, Korkut

Article | 2014 | Turkish Journal of Electrical Engineering and Computer Sciences22 ( 2 ) , pp.371 - 379

Wire antennas can be made wideband if the antenna is loaded with passive elements and connected to a lossless matching network. However, realization of the load component values and matching network can easily become impractical. In this study, using only a surface mount and standard component values, antenna loads and a matching network are optimized using genetic algorithms. The optimized design achieves a 25:1 bandwidth ratio, from 20 MHz to 500 MHz, with a maximum voltage standing wave ratio (VSWR) of 3.5 and minimum system gain of --5 dBi. The antenna system gain at azimuth is taken as the objective function and an exact penalt . . .y function is formulated to take into account the VSWR over the design frequency band. A loaded antenna is built and measured to corroborate the simulations results. The realized antenna is only 0.14 lambda long at 20 MHz Daha fazlası Daha az

Yeğin, Korkut

Article | 2009 | Turkish Journal of Electrical Engineering and Computer Sciences17 ( 3 ) , pp.231 - 239

The simplest way to solve for penetration through small apertures in conducting surfaces is to treat the body as a scatterer and determine the interior field as the sum of the incident field and the scattered field contributed by the current induced on the surface of the body. However, it is well known that, if the aperture is very small or if the penetrated field is very weak this method yields very inaccurate results, which, in turn, prohibits proper design of electronic systems, especially for electromagnetic compatibility and interference. Previously, alternative integral equations formulations were proposed to remedy this probl . . .em and applied to two-dimensional conducting cylinders with slots [1–2]. Application of these alternative techniques to threedimensional conducting bodies of revolution (BOR) is studied in this work. In addition, the reciprocity principle is used to recast a weak penetration problem into a weak radiation problem, and it is shown that the alternative formulations useful for weak penetration are also useful for weak radiation. The important features and relative accuracies of each formulation together with numerical results are detailed for mock missile-shape structures Daha fazlası Daha az