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Citation Count: 6
The 1st workshop on model-based verification & validation: Directed acyclic graph modeling of security policies for firewall testing
(2009) Tuglular, T.; Kaya, Ö.; Müftüoǧlu, C.A.; Belli, F.; Tuğlular, Tuğkan; Bilgisayar Mühendisliği Bölümü
Currently network security of institutions highly depend on firewalls, which are used to separate untrusted network from trusted one by enforcing security policies. Security policies used in firewalls are ordered set of rules where each rule is represented as a predicate and an action. This paper proposes modeling of firewall rules via directed acyclic graphs (DAG), from which test cases can be automatically generated for firewall testing. The approach proposed follows test case generation algorithm developed for event sequence graphs. Under a local area network setup with the aid of a specifically developed software for this purpose, generated test cases are converted to network test packets, test packets are sent to the firewall under test (FUT), and sent packets are compared with passed packets to determine test result. © 2009 IEEE.
Citation Count: 9
Achieving query performance in the cloud via a cost-effective data replication strategy
(Springer, 2021) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, Tolga; Ayav, Tolga; Bilgisayar Mühendisliği Bölümü
Meeting performance expectations of tenants without sacrificing economic benefit is a tough challenge for cloud providers. We propose a data replication strategy to simultaneously satisfy both the performance and provider profit. Response time of database queries is estimated with the consideration of parallel execution. If the estimated response time is not acceptable, bottlenecks are identified in the query plan. Data replication is realized to resolve the bottlenecks. Data placement is heuristically performed in a way to satisfy query response times at a minimal cost for the provider. We demonstrate the validity of our strategy in a performance evaluation study.
Citation Count: 15
Advanced Sensor and Detection Materials
(Wiley Blackwell, 2014) Tiwari A.; Demir, M.M.
Presents a comprehensive and interdisciplinary review of the major cutting-edge technology research areas-especially those on new materials and methods as well as advanced structures and properties-for various sensor and detection devices. The development of sensors and detectors at macroscopic or nanometric scale is the driving force stimulating research in sensing materials and technology for accurate detection in solid, liquid, or gas phases; contact or non-contact configurations; or multiple sensing. The emphasis on reduced-scale detection techniques requires the use of new materials and methods. These techniques offer appealing perspectives given by spin crossover organic, inorganic, and composite materials that could be unique for sensor fabrication. The influence of the length, composition, and conformation structure of materials on their properties, and the possibility of adjusting sensing properties by doping or adding the side-groups, are indicative of the starting point of multifarious sensing. The role of intermolecular interactions, polymer and ordered phase formation, as well as behavior under pressure and magnetic and electric fields are also important facts for processing ultra-sensing materials. The 15 chapters written by senior researchers in Advanced Sensor and Detection Materials cover all these subjects and key features under three foci: 1) principals and perspectives, 2) new materials and methods, and 3) advanced structures and properties for various sensor devices. © 2014 Scrivener Publishing LLC. All rights reserved.
Citation Count: 24
Advances in Electrospun Fiber-Based Flexible Nanogenerators for Wearable Applications
(Wiley-v C H verlag Gmbh, 2021) Arica, Tugce A.; Isik, Tugba; Guner, Tugrul; Horzum, Nesrin; Demir, Mustafa M.; Demir, Mustafa
In today's digital age, the need and interest in personal and portable electronics shows a dramatic growth trend in daily life parallel to the developments in sensors technologies and the internet. Wearable electronics that can be attached to clothing, accessories, and the human body are one of the most promising subfields. The energy requirement for the devices considering the reduction in device sizes and the necessity of being flexible and light, the existing batteries are insufficient and nanogenerators have been recognized a suitable energy source in the last decade. The mechanical energy created by the daily activities of the human body is an accessible and natural energy source for nanogenerators. Fiber-structured functional materials contribute to the increase in energy efficiency due to their effective surface to volume ratio while providing the necessary compatibility and comfort for the movements in daily life with its flexibility and lightness. Among the potential solutions, electrospinning stands out as a promising technique that can meet these requirements, allowing for simple, versatile, and continuous fabrication. Herein, wearable electronics and their future potential, electrospinning, and its place in energy applications are overviewed. Moreover, piezoelectric, triboelectric, and hybrid nanogenerators fabricated or associated with electrospun fibrous materials are presented.
Citation Count: 11
The amphibian and reptile species of Bozdaǧ (Ödemiş)
(2004) Kumlutaş,Y.; Özdemir,A.; Ilgaz,Ç.; Tosunoǧlu,M.
The herpetofauna of Bozdaǧ in western Anatolia was investigated. In the study area, 152 samples belonging to 22 species from 14 amphibian and reptile families were described. One of these species is an urodelan, 5 are anurans, 1 is a tortoise, 10 are lizards and 5 are snakes. A specimen of Eumeces schneideri was found at Bozdaǧ for the first time. © TÜBİTAK.
Citation Count: 1
Automation Architecture for Bayesian Network Based Test Case Prioritization and Execution
(Ieee, 2016) Ufuktepe, Ekincan; Tuglular, Tugkan; Tuğlular, Tuğkan; Bilgisayar Mühendisliği Bölümü
An automation architecture for Bayesian Network based test case prioritization is designed for software written in Java programming language following the approach proposed by Mirarab and Tahvildari [2]. The architecture is implemented as an integration of a series of tools and called Bayesian Network based test case prioritization and execution platform. The platform is triggered by a change in the source code, then it collects necessary information to be supplied to Bayesian Network and uses Bayesian Network evaluation results to run high priority unit tests.
Citation Count: 1
Behavior-Driven Development of Software Product Lines
(Institute of Electrical and Electronics Engineers Inc., 2021) Tuglular, T.; Coskun, D.E.; Tuğlular, Tuğkan; Bilgisayar Mühendisliği Bölümü
Software product lines (SPLs) develop families of similar software products, which share a standard set of features, and they build in variety via optional features. That means customers can select features according to their needs and come up with a product configuration. Then the SPL is expected automatically to generate and test the software product for the chosen configuration. There are various SPL solutions for the automatic generation of software products, but those SPLs lack automatic testing of the generated product. To overcome this shortcoming, the SPL should automatically compose a test suite according to the selected features, automatically execute the test suite on the product, and automatically generate a test report delivered to the customer with the product. This paper proposes such an approach through behavior driven development. The proposed method is evaluated with a smart home SPL. © 2021 IEEE.
Citation Count: 8
BODIPY-based organic color conversion layers for WLEDs
(Elsevier Sci Ltd, 2020) Yuce, Hurriyet; Guner, Tugrul; Dartar, Suay; Kaya, Beraat U.; Emrullahoglu, Mustafa; Demir, Mustafa M.; Demir, Mustafa
The usage of organic dyes in phosphor conversion layer of WLED is an attractive approach since they have high molar extinction coefficient and photostability. Various types of organic pigments have been employed for this purpose such as BODIPY, perylene diimide, Rhodamine B, pyrene, Nile red, etc. Among those, BODIPY-based organic dyes appear to be promising candidate for white light generation. In this work, for the first time, red and green emitting BODIPY-based organic molecules have been used as colour conversion layer. These molecules were associated with PMMA in DMF solution and the resulting solution was subjected to electrospinning. Colorful electrospun mats were embedded into PDMS matrix and their free-standing PDMS composite films were used as color conversion layers over blue LED to produce white light such that CRI of 95 and CCT of 4200 K was achieved. These values show that BODIPY-based organic molecules containing fiber composites are promising candidates to be used as color conversion layers for white light applications.
Citation Count: 3
Boolean Differentiation for Formalizing Myers' Cause-Effect Graph Testing Technique
(Ieee, 2015) Ayav, Tolga; Belli, Fevzi; Ayav, Tolga; Bilgisayar Mühendisliği Bölümü
Cause-Effect Graph Testing is a popular technique used for almost four decades. Based on Boolean algebra, this technique assists deriving test cases from a given specification informally written in a natural language. The present paper suggests Boolean differentiation for formalizing this technique. The new approach is applied to an example, borrowed from G. Myers, for demonstrating and analyzing its features. Evaluations show that the new approach outperforms Myers' approach in terms of the detected faults per test cases.
Citation Count: 11
Brucellosis in pregnancy: results of multicenter ID-IRI study
(Springer Verlag, 2019) Inan,A.; Erdem,H.; Elaldi,N.; Gulsun,S.; Karahocagil,M.K.; Pekok,A.U.; Beeching,N.J.
Brucellosis in pregnant women is reported to be associated with obstetric complications (OCs), and adequate data for human brucellosis during pregnancy are largely lacking. We performed this multicenter retrospective cross-sectional study to evaluate the epidemiology, clinical course, treatment responses, and outcomes of brucellosis among pregnant women. The study period comprised a 14-year period from January 2002 to December 2015. All consecutive pregnant women diagnosed with brucellosis in 23 participating hospitals were included. Epidemiological, clinical, laboratory, therapeutic, and outcome data along with the assessment data of the neonate were collected using a standardized questionnaire. Data of 242 patients were analyzed. The OC rate was 14.0% (34/242) in the cohort. Of the 242 women, 219 (90.5%) delivered at term, 3 (1.2%) had preterm delivery, 15 (6.2%) aborted, and 5 (2.1%) had intrauterine fetal demise. Seventeen (7.0%) of the newborns were considered as low birth weight. Spontaneous abortion (6.1%) was the commonest complication. There were no maternal or neonatal deaths and pertinent sequelae or complications were not detected in the newborns. Splenomegaly (p = 0.019), nausea and/or vomiting (p < 0.001), vaginal bleeding (p < 0.001), anemia (blood hemoglobin < 11 g/dL; p < 0.001), high level of serum aspartate aminotransferase (> 41 IU/L; p = 0.025), oligohydramnios on ultrasonography (p = 0.0002), history of taking medication other than Brucella treatment during pregnancy (p = 0.027), and Brucella bacteremia (p = 0.029) were the significant factors associated with OCs. We recommend that pregnant women with OC or with fever should be investigated for brucellosis if they live in or have traveled to an endemic area. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Citation Count: 255
Cell proliferation and cytotoxicity assays
(Bentham Science Publishers B.V., 2016) Baran, Yusuf; Kiraz,Y.; Baran,Y.
Cell viability is defined as the number of healthy cells in a sample and proliferation of cells is a vital indicator for understanding the mechanisms in action of certain genes, proteins and pathways involved cell survival or death after exposing to toxic agents. Generally, methods used to determine viability are also common for the detection of cell proliferation. Cell cytotoxicity and proliferation assays are generally used for drug screening to detect whether the test molecules have effects on cell proliferation or display direct cytotoxic effects. Regardless of the type of cell-based assay being used, it is important to know how many viable cells are remaining at the end of the experiment. There are a variety of assay methods based on various cell functions such as enzyme activity, cell membrane permeability, cell adherence, ATP production, co-enzyme production, and nucleotide uptake activity. These methods could be basically classified into different categories: (I) dye exclusion methods such as trypan blue dye exclusion assay, (II) methods based on metabolic activity, (III) ATP assay, (IV) sulforhodamine B assay, (V) protease viability marker assay, (VI) clonogenic cell survival assay, (VII) DNA synthesis cell proliferation assays and (V) raman micro-spectroscopy. In order to choose the optimal viability assay, the cell type, applied culture conditions, and the specific questions being asked should be considered in detail. This particular review aims to provide an overview of common cell proliferation and cytotoxicity assays together with their own advantages and disadvantages, their methodologies, comparisons and intended purposes. © 2016 Bentham Science Publishers.
Citation Count: 38
Clinical and laboratory features, complications and treatment outcome of brucellosis in childhood and review of the literature
(2011) Uluǧ,M.; Yaman,Y.; Yapici,F.; Can-Uluǧ,N.
Brucellosis, whether in an endemic region or not, remains a diagnostic puzzle due to occasional misleading unusual presentations and non-specific symptoms. The aim of this study was to evaluate the clinical and laboratory findings, complications and treatment outcome of brucellosis in children in southeastern Anatolia, Turkey. This study focuses on the frequency of clinical and laboratory findings and complications in cases with brucellosis. Of 22 patients, 8 (36.3%) were female and 14 (63.7%) were male. Fever, malaise, lack of appetite, arthralgia, and night sweating were the main presenting symptoms overall. Hematologic complications (n=13, 59.1%) were most common, followed by skeletal (n=7, 31.8%) and cutaneous system (n=1, 4.5%). Brucellosis may affect any organ system and imitate a variety of clinical entities. Diagnosis of brucellosis should be considered whenever there is a febrile illness associated with rheumatological complaints. Consequently, early recognition of the infection, prolonged antibiotic treatment and careful long-term follow-up should improve the patient outcome.
Citation Count: 4
Code change sniffer: Predicting future code changes with Markov chain
(Institute of Electrical and Electronics Engineers Inc., 2021) Ufuktepe, E.; Tuglular, T.; Tuğlular, Tuğkan; Bilgisayar Mühendisliği Bölümü
Code changes are one of the essential processes of software evolution. These changes are performed to fix bugs, improve quality of software, and provide a better user experience. However, such changes made in code could lead to ripple effects that can cause unwanted behavior. To prevent such issues occurring after code changes, code change prediction, change impact analysis techniques are used. The proposed approach uses static call information, forward slicing, and method change information to build a Markov chain, which provides a prediction for code changes in the near future commits. For static call information, we utilized and compared call graph and effect graph. We performed an evaluation on five open-source projects from GitHub that varies between 5K-26K lines of code. To measure the effectiveness of our proposed approach, recall, precision, and f-measure metrics have been used on five open-source projects. The results show that the Markov chain that is based on call graph can have higher precision compared to effect graph. On the other hand, for small number of cases higher recall values are obtained with effect graph compared to call graph. With a Markov chain model based on call graph and effect graph, we can achieve recall values between 98%-100%. © 2021 IEEE.
Citation Count: 7
Comparison of the body size and age structure of Lebanon lizard, Phoenicolacerta laevis (Gray, 1838) at different altitudes in Turkey
(Senckenbergische Naturforschende Gesellschaft, 2018) Üzüm,N.; Ilgaz,Ç.; Avci,A.; Candan,K.; Güler,H.; Kumlutaş,Y.
In this study, comparison of a life history traits (e.g. body size, age at maturity, longevity) of two populations of Phoenicolacerta laevis from different altitudes is being carried out (Anamur, 22 m a.s.l.; Andirin, 1.083 m a.s.l.) for the first time. We applied phalangeal skeletochronology to obtain the age of juveniles and adults. Age was determined by counting the lines of arrested growth (LAGs) in cross-sections. Males in both populations were the larger of the two sexes and a male biased sexual dimorphism was determined for both populations. Body size (SVL) was similar in both sexes and populations. Age of maturity was calculated to be 3 years of age for males and females in both populations. The average age of males and females was calculated as 6.62 ± 0.37 (Mean±SE) and 6.11 ± 0.26 years in Anamur, and 6.15 ± 0.51 and 5.26 ± 0.24 years in Andirin. There was statistically significant variation between sexes, but no significant difference in populations was found in relation to age. For both populations, a significant positive correlation was found between age and SVL in males and females. © Senckenberg Gesellschaft für Naturforschung, 2018.
Citation Count: 1
A Comprehensive Study on Burst Pressure Performance of Aluminum Liner for Hydrogen Storage Vessels
(Asme, 2021) Kangal, Serkan; Say, A. Harun; Ayakda, Ozan; Kartav, Osman; Aydin, Levent; Artem, H. Secil; Beylergil, Bertan
This paper presents a comparative study on the burst pressure performance of aluminum (Al) liner for type-III composite overwrapped pressure vessels (COPVs). In the analysis, the vessels were loaded with increasing internal pressure up to the burst pressure level. In the analytical part of the study, the burst pressure of the cylindrical part was predicted based on the modified von Mises, Tresca, and average shear stress criterion (ASSC). In the numerical analysis, a finite element (FE) model was established in order to predict the behavior of the vessel as a function of increasing internal pressure and determine the final burst. The Al pressure vessels made of Al-6061-T6 alloy with a capacity of 5 L were designed. The manufacturing of the metallic vessels was purchased from a metal forming company. The experimental study was conducted by pressurizing the Al vessels until the burst failure occurred. The radial and axial strain behaviors were monitored at various locations on the vessels during loading. The results obtained through analytical, numerical, and experimental work were compared. The average experimental burst pressure of the vessels was found to be 279 bar. The experimental strain data were compared with the results of the FE analysis. The results indicated that the FE analysis and ASSC-based elastoplastic analytical approaches yielded the best predictions which are within 2.2% of the experimental burst failure values. It was also found that the elastic analysis underestimated the burst failure results; however, it was effective for determining the critical regions over the vessel structure. The strain behavior of the vessels obtained through experimental investigations was well correlated with those predicted through FE analysis.
Citation Count: 15
Controlling spontaneous emission of CdSe nanoparticles dispersed in electrospun fibers of polycarbonate urethane
(2009) Demir M.M.; Soyal D.; Ünlü C.; Kuş M.; Özçelik, S.
Luminescent fibrous composite films consisting of submicrometer diameter fibers were prepared by electrospinning of segmented polycarbonate urethane (PCU) in dimethyl formamide and tri-n-octylphosphine oxide (TOPO)-capped CdSe nanocrystals (5 nm in diameter) in toluene. Using a pair of conductive electrodes separated with an air gap, we successfully produced randomly deposited and uniaxially aligned electrospun fibers. The surface structure of the electrospun fibers was studied using atomic force microscopy (AFM) and was compared to the corresponding film prepared by casting. In cast film, tapping mode AFM imaging suggests that hard urethane segments organize into rodlike morphology dispersed in soft polycarbonate. When PCU/CdSe dispersions were subjected to electrospinning, copolymer domains were forced to arrange into lamella along the fiber axis due to elongational flow and high stretching. Molecular orientation in the domains of the composite fibers was confirmed by polarized infrared spectroscopy. We demonstrated that formation of the oriented domains by electrospinning develops a hierarchical structure, which consequently modifies spectral properties because new multiple sharp lines appeared in the photoluminescence (PL) spectra of the fibers. In contrast to randomly deposited fibers, the PL intensity of uniaxially aligned fibers was found to be angle dependent. We propose that the elongated internal structure within the fibers controls the spontaneous emission of CdSe nanoparticles dispersed throughout the electrospun mat. A discussion on the nature of the controlled spontaneous emission is provided. © 2009 American Chemical Society.
Citation Count: 11
Cryopreservation of a cell-based biosensor chip modified with elastic polymer fibers enabling ready-to-use on-site applications
(Elsevier Advanced Technology, 2021) Ozsoylu, Dua; Isik, Tugba; Demir, Mustafa M.; Schoning, Michael J.; Wagner, Torsten; Demir, Mustafa
An efficient preservation of a cell-based biosensor chip to achieve a ready-to-use on-site system is still very challenging as the chip contains a living component such as adherent mammalian cells. Herein, we propose a strategy called on-sensor cryopreservation (OSC), which enables the adherent cells to be preserved by freezing (-80 degrees C) on a biosensor surface, such as the light-addressable potentiometric sensor (LAPS). Adherent cells on rigid surfaces are prone to cryo-injury; thus, the surface was modified to enhance the cell recovery for OSC. It relies on i) the integration of elastic electrospun fibers composed of polyethylene vinyl acetate (PEVA), which has a high thermal expansion coefficient and low glass-transition temperature, and ii) the treatment with O-2 plasma. The modified sensor is integrated into a microfluidic chip system not only to decrease the thermal mass, which is critical for fast thawing, but also to provide a precisely controlled micro-environment. This novel cryo-chip system is effective for keeping cells viable during OSC. As a proof-of-concept for the applicability of a ready-to-use format, the extracellular acidification of cancer cells (CHO-K1) was evaluated by differential LAPS measurements after thawing. Results show, for the first time, that the OSC strategy using the cryo-chip allows label-free and quantitative measurements directly after thawing, which eliminates additional post-thaw culturing steps. The freezing of the chips containing cells at the manufacturing stage and sending them via a cold-chain transport could open up a new possibility for a ready-to-use on-site system.
Citation Count: 11
Design of Polymeric Antiscalants Based on Functional Vinyl Monomers for (Fe, Mg) Silicates
(Amer Chemical Soc, 2017) Topcu, Gokhan; Celik, Asli; Baba, Alper; Demir, Mustafa M.; Demir, Mustafa
Silica/silicate scaling is one of a few detrimental problems that cause high economical loss in the geothermal and petroleum fields. The prevention of silica/silicate has been attempted using antiscalants with functional groups, particularly -NH2; however, metal silicates are commonly found in the fields, and the antiscalants developed thus far are not effective against these compounds. In this work, polymeric antiscalants have been developed by merging two or-snore functional-comonomers consisting of various chelating groups for metal cations. Homo- and copolymers of acrylamide (AM), the sodium salt of vinyl sulfonic acid (VSA), and vinyl phosphonic acid (VPA) were synthesized to examine their antiscaling performance against metal silicate scaling. Lab-scale metal silicates were obtained in a pressured autoclave reactor. The, antiscalants were tested at various dosages (25, 50, and 100 ppm), and their effects were investigated from the leftover decaritates after isolation of the solid precipitates. The polymeric antiscalants were found to be particularly effective against metal silicates and ineffective against simple silica precipitates. Acidic groups may be coordinating the metal cations, which prevents the-formation of precipitates. Among these acidic comonomers; VSA-containing polymers, in particular, increased the solubility-of metal silicates.
Citation Count: 0
Determination of activation energy for carbon/epoxy prepregs containing carbon nanotubes by differential scanning calorimetry
(Sage Publications Ltd, 2023) Uz, Yusuf Can; Tanoglu, Metin; Tanoğlu, Metin
The aim of the present study is the thermal characterization of laboratory-scale carbon fiber/epoxy-based prepregs by incorporating single-wall carbon nanotubes (SWCNTs). Investigation of the cure behavior of a prepreg system is crucial for the characterization and optimization of the fiber reinforced polymeric (FRP) composite. To affect dispersion characteristics, SWCNTs were functionalized by oxidizing their surface with carboxyl (-COOH) group using an acid treatment. The modified resin system contained 0.05, 0.1, and 0.2 wt. % functionalized SWCNTs (F-SWCNTs). Carbon fiber (CF) reinforced prepregs containing various amount of F-SWCNTs were prepared using drum-type winding technique. FTIR was performed to identify new bonding groups formed after the functionalization of SWCNTs. Cure kinetics of prepregs prepared with/without F-SWCNTs were investigated using isoconversional methods.
Citation Count: 8
Development and analysis of composite overwrapped pressure vessels for hydrogen storage
(Sage Publications Ltd, 2021) Kartav, Osman; Kangal, Serkan; Yuceturk, Kutay; Tanoglu, Metin; Aktas, Engin; Artem, H. Secil; Tanoğlu, Metin
In this study, composite overwrapped pressure vessels (COPVs) for high-pressure hydrogen storage were designed, modeled by finite element (FE) method, manufactured by filament winding technique and tested for burst pressure. Aluminum 6061-T6 was selected as a metallic liner material. Epoxy impregnated carbon filaments were overwrapped over the liner with a winding angle of +/- 14 degrees to obtain fully overwrapped composite reinforced vessels with non-identical front and back dome layers. The COPVs were loaded with increasing internal pressure up to the burst pressure level. During loading, deformation of the vessels was measured locally with strain gauges. The mechanical performances of COPVs designed with various number of helical, hoop and doily layers were investigated by both experimental and numerical methods. In numerical method, FE analysis containing a simple progressive damage model available in ANSYS software package for the composite section was performed. The results revealed that the FE model provides a good correlation as compared to experimental strain results for the developed COPVs. The burst pressure test results showed that integration of doily layers to the filament winding process resulted with an improvement of the COPVs performance.

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