Wireless Heterogeneous Networks and Next Generation Internet

The recent advances in wireless access technologies as well as the increasing number of mobile applications have made Wireless Internet a reality. A wide variety of bandwidth demanding services including high speed data delivery and multimedia communication have been materialized through the convergence of the next generation Internet and heterogeneous wireless networks. However, providing even higher bandwidth and richer applications necessitates a fundamental understanding of wireless Internet architecture and the interactions between heterogeneous users. Consequently, fundamental advances in many concepts of the wireless Internet are required for the ultimate goal of communication anytime anywhere. This special issue of the ACM Mobile Networks and Applications Journal is dedicated to the recent advances in the area of Wireless Internet. We accepted 10 papers out of 59 submissions from all over the world with a 17% acceptance rate. Papers describing management schemes, protocols, models, evaluation methods, and experimental studies of Wireless Internet are included in this special issue to provide a broad view of recent advances in this field

A practical approach for optical characterization of a film coated on the optical fiber

Phase Diffraction (PD) Phase Diffraction. which is a result of the interaction of light waves with a transparent object, is exploited to characterize precisely optical properties of dielectric films coated on the optical fiber without harming any feature of the sample. Typical fiber sensor applications require films coated on the side surface of the optical fiber and optical properties of that curved films are crucial for design purposes. In this study, three Polyvinyl Alcohol (PVA) films are prepared, their thicknesses are estimated based on the phase diffraction method by fitting experimental results with a mathematical model within 2.3% error. The outcomes of this practical method show good agreement with findings of the destructive Scanning Electron Microscopy (SEM) measurements. The method has the potential to allow real time monitoring abrupt changes of surrounding medium's properties and to examine coating quality (i.e. thickness uniformity) of the film.Scientific and Technological Research Council of Turkey (TUBITAK 114E006

Wireless Heterogeneous Networks and Next Generation Internet

The recent advances in wireless access technologies as well as the increasing number of mobile applications have made Wireless Internet a reality. A wide variety of bandwidth demanding services including high speed data delivery and multimedia communication have been materialized through the convergence of the next generation Internet and heterogeneous wireless networks. However, providing even higher bandwidth and richer applications necessitates a fundamental understanding of wireless Internet architecture and the interactions between heterogeneous users. Consequently, fundamental advances in many concepts of the wireless Internet are required for the ultimate goal of communication anytime anywhere. This special issue of the ACM Mobile Networks and Applications Journal is dedicated to the recent advances in the area of Wireless Internet. We accepted 10 papers out of 59 submissions from all over the world with a 17% acceptance rate. Papers describing management schemes, protocols, models, evaluation methods, and experimental studies of Wireless Internet are included in this special issue to provide a broad view of recent advances in this field

Gaussian solitary waves to Boussinesq equation with dual dispersion and logarithmic nonlinearity

This paper discusses shallow water waves that is modeled with Boussinesq equation that comes with dual dispersion and logarithmic nonlinearity. The extended trial function scheme retrieves exact Gaussian solitary wave solutions to the model

IF çeliklerin MIG-BRAZING yöntemi ile birleştirilmesi ve mekanik özelliklerinin incelenmesi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Otomotiv endüstrisinde iç ve dış panellerin üretiminde kullanılan arayer atomsuz (Interstitial–Free Steel) çelikler, çok az miktarlarda karbon ve azot içermeleri nedeniyle pres altında şekillendirmeye uygun çeliklerdir. Arayer atomsuz çeliklerde, şekillendirilebilme özelliğini olumsuz yönde etkileyen arayer atomlarının (C ve N), çelik üretim prosesi esnasında bileşimden kontrollü bir biçimde uzaklaştırılması Titanyum (Ti) ve/veya Niobyum (Nb) atomlarının C ve N atomları ile reaksiyona girerek çökelti fazları oluşturması ile olmaktadır. Araba montajlarında gaz metal ark kaynağı gibi geleneksel yöntemler kullanıldığında ana metal ve kaynaklanan bölge, çinkonun buharlaşmasıyla oksidasyona uğramaktadır. Çinkonun buharlaşma riskini azaltmak için, düşük ısı girdisi destekli yeni kaynak proseslerinde mesafe kat edilmeye başlandı. Bu çalışmaların sonuçlarının bir tanesi de, MIG kaynağının avantajları (yüksek damla geçişi, yüksek kaynak hızı ve otomasyona uygunluk) ile lehimlemenin (kaynaklanan malzemeyi ergitmeksizin ve mekanik özelliklerinde bir değişme olmaksızın) düşük ısı girdisini birleştiren, MIG lehimlemedir. Bu çalışmada 0,9 mm kalınlığa sahip IF çelik saclar MIG-lehimleme yöntemi kullanılarak bakır esaslı bir tel olan CuAl8 teli ile birleştirilmiştir. Numuneler iki farklı bağlantı biçimi olan bindirme ve alın bağlantılar olarak hazırlanmıştır. Lehimleme tatbikleri üç farklı parametrede, akım şiddeti, lehim ilerleme hızı ve gaz basıncı olarak incelenmiştir. MIG-lehimlenmiş malzemelerin mukavemet özellikleri, çekme mukavemeti ve bağlantı bölgesi arasındaki mikrosertlik dağılımları incelenmiştir. Makro ve mikroyapı tetkiklerinde optik mikroskop, taramalı elektron mikroskobu (SEM) ve noktasal element analiz cihazı EDS kullanıldı. Bu çalışmada akım şiddeti, lehim ilerleme hızı ve gaz basıncının lehimlenen bağlantı bölgesi ve IF çeliği arasındaki geçiş bölgesinin mikroyapısı ve mikrosertliği üzerindeki dağılımları araştırılmıştır.Interstitial free steels (if steels) are very suitable material for automotive industry and they are used for inner and outer body panel applications due to their high formability properties. They have extremely high formability characteristics under forming presses. Interstitials damages formability characteristics of steel. Elimination of interstitials (C and N) is achieved through careful control of the steelmaking process by the addition of titanium and/or niobium to react with carbon and nitrogen to form precipitates. In car assembly, where conventional welding processes like gas metal arc welding (GMAW) are used,the zinc coating is subject to severe evaporation and oxidation, leaving the weld bead and part of the base metal unprotected against subsequent oxidation. To reduce the risk of zinc evaporation, new welding processes with a low heat supply have begun to gain ground, for example MIG-brazing, which combines the advantages of the MIG process (high deposition rate, high welding speed and adaptable to automation) and brazing (without any intense fusion of the welded parts and without any appreciable alteration of the mechanical properties of the base metal and the coating applied). In this study, IF steel plates having 0,9 mm thickness were joined by copper-based CuAl8 wire in gas metal arc brazing technique. Specimens were prepared in two different joining forms as butt joint and overlap joint. Brazing operations were done with three different parameters, current intensities, travel speeds and shielding gas. Tensile strength, microstructure of brazed materials, and their micro hardness distribution throughout joining were determined. In macro and microstructure examinations, stereo optical microscope, scanning electron microscope (SEM), SEM/energy dispersive spectroscopy was used. This study investigated effects of current intensities, travel speeds and shielding gas on microstructure and microhardness distribution of transition zone between IF steel and brazed metal of joined material

İnsanlardan ve hayvanlardan i̇zole edilen blandm-5 üreten karbapenem dirençli escherichia coli kökenlerinin plazmidlerı üstünde bulunan direnç gen tanımlayıcılarının i̇n silico analizi

Due to their ability to resist endpoint antimicrobials such as carbapenem, it is very important to detect and monitor multi-drug resistant Gram negative strains with plasmids containing genes such as blaNDM-5 by new molecular methods. This study aimed to perform in silico analysis of resistance gene identifiers on human and animal-derived blaNDM-5 plasmids found in open databases, which were analyzed by new whole genome sequencing techniques and to compare these resistance genes. The plasmid genomic sequences of 4 human and 2 animal E. coli strains containing blaNDM-5 genes included in our study were analyzed in Silico using the Resistance Gene Identifier (RGI) option of the comprehensive antibiotic resistance gene database using default values. Human and animal strains included in our study were found to have different antimicrobial resistance genes in addition to blaNDM-5. All plasmids were found to have at least 8 perfect antimicrobial resistance gene sequences matches. When the resistance gene identifiers in all plasmids were examined, 35 resistance gene identifiers were found. Besides blaNDM-5, mphA, qacEdelta1 and sul1 were found in all plasmids. As a conclusion, it was determined by our study results that, regardless of the source, there may be different antimicrobial resistance gene identifiers besides the blaNDM-5 resistance gene in plasmids. We are of the opinion that routine molecular surveillance studies should be carried out considering the one health approach of Gram-negative pathogens such as E. coli, which can contain plasmids that cause multi-drug resistance and can be isolated from all sources.Karbapenem gibi son nokta antimikrobiyallere direnç yetenekleri dolayısıyla, blaNDM-5 gibi genler ihtiva eden plazmidlere sahip çoklu ilaç direnci gösteren Gram negatif kökenlerin yeni moleküler yöntemlerle tespiti önemlidir. Biz de çalışmamızda bu yeni tekniklerle tüm genom sekans analizi yapılan ve açık veritabanlarında bulunan insan ve hayvan kaynaklı blaNDM-5 plazmidleri üstünde bulunan direnç gen tanımlayıcılarının in silico analizini yapmayı ve bu direnç genlerini karşılaştırmayı amaçladık. Çalışmamıza dahil edilen 4 insan ve 2 hayvan kaynaklı, blaNDM-5 geni içeren E.coli kökenlerine ait plazmid genomik dizileri, varsayılan değerler kullanılarak kapsamlı antibiyotik direnç gen veritabanının, direnç geni tanımlayıcı (RGI) seçeneği kullanılarak bilgisayar ortamında analiz edildi. Çalışmamıza dahil edilen insan ve hayvan kaynaklı kökenlerde blaNDM-5 yanında farklı antimikrobiyal direnç genlerinin de olduğu tespit edildi. Tüm plazmidlerin en az 8 mükemmel antimikrobiyal direnç gen dizisi eşleşmesi gösterdiği saptandı. Tüm plazmidlerde bulunan direnç gen tanımlayıcıları incelendiğinde 35 direnç gen tanımlayıcısı saptandı. blaNDM-5 yanında, mphA, qacEdelta1 ve sul1’in bütün plazmidlerde olduğu tespit edildi. Sonuç olarak, kaynak fark etmeksizin, plazmidlerde, blaNDM-5 direnç geni yanında farklı antimikrobiyallere direnç gen tanımlayıcılarının da olabildiği çalışma sonucunda tespit edilmiştir. Çoklu ilaç direncine neden olan plazmidleri ihtiva edebilen ve tüm kaynaklardan izole edilebilen E. coli gibi Gram negatif patojenler üzerinde tek sağlık yaklaşımı düşünülerek rutin moleküler surveyans çalışmalarının yapılması gerektiği kanaatindeyiz

Cooperative Spectrum Sensing in Cognitive Radio Networks Using Multidimensional Correlations

In this paper, a multidimensional-correlation-based sensing scheduling algorithm, (CORN)2, is developed for cognitive radio networks to minimize energy consumption. A sensing quality metric is defined as a measure of the correctness of spectral availability information based on the fact that spectrum sensing information at a given space and time can represent spectrum information at a different point in space and time. The scheduling algorithm is shown to achieve a cost of sensing (e.g., energy consumption, sensing duration) arbitrarily close to the possible minimum, while meeting the sensing quality requirements. To this end, (CORN)2 utilizes a novel sensing deficiency virtual queue concept and exploits the correlation between spectrum measurements of a particular secondary user and its collaborating neighbors. The proposed algorithm is proved to achieve a distributed and arbitrarily close to optimal solution under certain, easily satisfied assumptions. Furthermore, a distributed Selective-(CORN)2 (S-(CORN)2) is introduced by extending the distributed algorithm to allow secondary users to select collaboration neighbors in densely populated cognitive radio networks. In addition to the theoretically proved performance guarantees, the algorithms are evaluated through simulations

(CORN)\u3csup\u3e2\u3c/sup\u3e: Correlation-Based Cooperative Spectrum Sensing in Cognitive Radio Networks

In this paper, (CORN)2, a correlation-based, optimal sensing scheduling algorithm is developed for cognitive radio networks to minimize energy consumption. A sensing quality metric is defined as a measure of the correctness of spectral availability information. The optimal scheduling algorithm is shown to minimize the cost of sensing (e.g., energy consumption, sensing duration) while meeting the sensing quality requirements. To this end, (CORN)2 utilizes a novel sensing deficiency virtual queue concept and exploits the correlation between spectrum measurements of a particular secondary user and its collaborating neighbors. The proposed algorithm is further proved to achieve a distributed and optimal solution under certain, easily satisfied assumptions. In addition to the theoretically proved performance guarantees, the proposed algorithm is also evaluated through simulations

A fully discrete ε-uniform method for convection-diffusion problem on equidistant meshes

For a singularly-perturbed two-point boundary value problem, we propose an ε-uniform finite difference method on an equidistant mesh which requires no exact solution of a differential equation. We start with a full-fitted operator method reflecting the singular perturbation nature of the problem through a local boundary value problem. However, to solve the local boundary value problem, we employ an upwind method on a Shishkin mesh in local domain, instead of solving it exactly. We further study the convergence properties of the numerical method proposed and prove it nodally converges to the true solution for any ε

Cooperative Spectrum Sensing in Cognitive Radio Networks Using Multidimensional Correlations

In this paper, a multidimensional-correlation-based sensing scheduling algorithm, (CORN)2, is developed for cognitive radio networks to minimize energy consumption. A sensing quality metric is defined as a measure of the correctness of spectral availability information based on the fact that spectrum sensing information at a given space and time can represent spectrum information at a different point in space and time. The scheduling algorithm is shown to achieve a cost of sensing (e.g., energy consumption, sensing duration) arbitrarily close to the possible minimum, while meeting the sensing quality requirements. To this end, (CORN)2 utilizes a novel sensing deficiency virtual queue concept and exploits the correlation between spectrum measurements of a particular secondary user and its collaborating neighbors. The proposed algorithm is proved to achieve a distributed and arbitrarily close to optimal solution under certain, easily satisfied assumptions. Furthermore, a distributed Selective-(CORN)2 (S-(CORN)2) is introduced by extending the distributed algorithm to allow secondary users to select collaboration neighbors in densely populated cognitive radio networks. In addition to the theoretically proved performance guarantees, the algorithms are evaluated through simulations