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Unit Cell Calculations Under Fully Characterized Stress States
No full textThe available numerical methods for performing finite element unit cell calculations under stress states evolving in a predefined manner restrict the most general stress state to a single shear stress component superimposed on three normal stress components. The present study builds on and extends state of the art such that the behavior of a unit cell under the most complex stress states, comprising three shear and three normal stress components, can be explored. The proposed method is implemented in the commercial finite element software Abaqus. Three-dimensional cubic unit cells containing either a void or a particle at the center and subjected to various stress states showed that the developed method is accurate and computationally efficient. Furthermore, simulations using voided unit cells demonstrate that ductile failure is an anisotropic process, with anisotropy intensifying in the presence of shear loads. That is, void growth and strain localization leading to ductile fracture are influenced by the relative ratios of all shear stress components as well as the stress triaxiality and the Lode parameter
A Harmonic Radar Simulator for Modulated Waveforms
No full textIn this study a software simulator is developed to investigate the operation performance of a pulsed harmonic radar. The simulator is capable of modulating transmitted RF signal with polyphase P1, P2, P3 and P4 codes, LFM and FMCW codes. Transmitted power, gain of the transmit and receive antennas and detected harmonic number are all configurable in the simulator. Distance to the target and radar cross section(RCS) of the target can be modified and received signal level is calculated using nonlinear harmonic radar equation which is also implemented within the simulator. It is able to realize pulse integration, a method which is used to increase processing gain of the radar. Additionally, to observe the effect of clutter rejection property of the harmonic radar, clutter can be added to the received signal using different statistical clutter models. Target characteristic can be either imported from any circuit simulator or can be generated analytically by the simulator itself. Developed simulator can be used as a tool in designing harmonic radar systems before going into detailed implementation
Being Small for Gestational Age Affect Neurodevelopmental Outcomes in Very Preterm Infants
No full textIntroduction: There is insufficient data on neurodevelopmental outcomes of infants small for gestational age (SGA) with = 30 weeks of gestation. The aim of our study was to compare the neurodevelopmental outcomes of preterm infants who are = 30 weeks, in terms of being SGA or appropriate for gestational age (AGA). Materials and Methods: The data of infants who were born at = 30 GW, were evaluated retrospectively. Neurological examinations and developmental assessment using Bayley Scales of Infant Development 2nd edition was performed at the corrected age of 18-24 months. Results: The data of 228 infants of whom 65 were SGA and 163 were AGA was evaluated in terms of neurodevelopment at the corrected age of 18-24 months. The mean gestational age (GA) was 28.4 +/- 1.1 in both groups (p=0.82) and the mean BW was 810 +/- 135 g in the SGA group and 1175 +/- 183 g in the AGA group (p0.001). The SGA group had significantly lower Mental Development Index (p=0.01) and Psychomotor Development Index (p0.001). In multivariate regression analysis, SGA was identified as an independent risk factor for neurodevelopmental delay (RR: 2.27; p=0.02). Conclusion: Being SGA is a risk factor for neurodevelopmental impairment of preterm infants (= 30 GW)
Relationship Between C-Reactive Protein/Albumin Ratio and Dipper/Nondipper Pattern in Normotensive Individuals
No full textObjective Nondipper blood pressure pattern plays an important role in cardiovascular events even in normotensive individuals. The relationship between CRP (C-reactive protein)/albumin ratio (CAR), a valuable marker of inflammation and cardiovascular diseases, has been studied for a long time. We aimed to investigate the relationship between CAR and dipper/nondipper pattern in normotensive subjects. Methods A total of 78 dipper and 78 nondipper participants, based on ambulatory blood pressure monitoring (ABPM), were retrospectively included in our study. CAR and other parameters of all participants were collected from blood samples taken at the time of monitoring. Results CAR was significantly higher in the nondipper group than dipper group (P = 0.001). CAR was negatively and significantly correlated with nocturnal SBP fall ratio and nocturnal DBP fall ratio (P 0.001). CRP/albumin ratio was found significantly and independently associated with the nondipper pattern (P = 0.002). Conclusion We found that normotensive individuals with nondipping pattern tend to have increased CAR. Increased inflammatory response could contribute to increase in the atherosclerotic risk in nondippers compared with dippers even in a normotensive profile
Rf Güç Yükselticiler için Sayisal Kontrol Tabanli Gan Transistörlü Zarf İzleyici Güç Kaynagi Tasarimi
No full textWireless communication, which is used in mobile phones, modems, base stations and many other areas has gained importance with increasing demand and developing technology. RF power amplifiers are one of the most important blocks in wireless communication. Power amplifiers consume the most power in RF systems. Therefore, efficiency is one of the most important parameters in power amplifier design. Classical power amplifiers are not efficient. Envelope tracking is one of the voltage modulation techniques that is used to increase efficiency in power amplifiers. In this method, the power source feeding the power amplifier creates an output voltage according to the needs of the RF system by increasing and decreasing the output voltage. In this study, envelope tracking power supply design is explained. This supply is capable of operating with 9-12V input voltage, has 750 KHz switching frequency, follows reference signal up to 5kHz, supplies 1A output current and 5V output voltage. The power supply is a design with synchronous buck converter topology. Also this study includes digital control design providing flexible solutions, use of GaN (Gallium Nitride) transistors that work more efficiently at high speeds and various analyzes.Cep telefonlari, kablosuz modemler, baz istasyonlari ve daha birçok alanda kullanilan kablosuz haberlesme artan talep ve gelisen teknoloji ile birlikte oldukça önem kazanmistir. Kablosuz haberlesmenin önemli bir blogunu RF güç yükselticiler olusturur. RF sistemlerde en çok güç tüketen birimlerin basinda güç yükselteçleri gelir. Bu nedenle güç yükselteç tasariminda verim en önemli parametrelerden biridir. Klasik güç yükselteçleri verimli degildir. Güç yükselteçlerde verimliligi arttirmak için kullanilan gerilim modülasyon tekniklerinden biri de zarf izleme yöntemidir. Bu yöntemde güç yükseltecini besleyen güç kaynagi referans aldigi sinyale göre çikis gerilimini yükseltip alçaltarak RF sistemin ihtiyacina göre çikis gerilimi olusturur. Bu çalismada güç yükselteçlerde zarf izleyen anahtarlamali güç kaynagi tasarimi anlatilmistir. Bu güç kaynagi 9V-12V giris geriliminde çalisan, 750 KHz anahtarlama frekansina sahip, 5 KHz'e kadar zarf izleyebilen, 1A çikis akimi ve 5V çikis gerilimi saglayabilen bir tasarimdir. Bu güç kaynagi senkron alçaltan çevirici topolojiyle tasarlanmistir. Bu çalismada ayrica esnek çözümler sunan sayisal kontrolcü tasarimina, yüksek hizlarda daha verimli çalisan GaN (Gallium Nitride) transistör kullanimina ve çesitli analizlere yer verilmistir
Insansiz Hava Araçlari için Minimum Gecikme Kosulu Altinda Optimum Yol Atama Yöntemleri
No full textNowadays, access to information is a very important need. This need can also be met by the applications of wireless communication systems in various fields. Unmanned Aerial Vehicles (UAVs), which has an significant place in studies in academia and industry, not only makes people's lives easier in many areas, but also have various applications in the field of wireless communication. Within the scope of this thesis, accessing information with a UAV-assisted system in sensor networks for time-critical applications has been examined. Data collection with UAV is a new technology with many practical applications. The data collected by the UAV should be brought to the data center where it will be used as quickly as possible. In academic studies, the delay in bringing the data collected by the UAV to the data center is entered into problems with the Age of Information (AoI) parameter as a objective or constraint. In this study, AoI is used as a performance metric that affects both communication time and flight time. Instead of the idea that the UAV, which is very common in the literature, travels the sensors one by one and performs the data collection process, the sensors are discussed in groups in this study. In this study, dual sensor groups were studied to see the effect of grouping idea on performance. Starting from the data center, the UAV aims to hover at one point on the line segments formed between the sensors in the groups, collect data via multiple access channels and then return to the data center. With the formation of dual sensor groups, the UAV will not be able to visit each sensor separately, so it will be able to follow a shorter path in its trajectory and reach shorter communication times with multiple access channel communication. Two trajectory design algorithms are proposed to minimize the maximum AoI in the sensors. In both algorithms, the UAV communicates with the sensors via multiple access channel. In the first algorithm, the UAV hovers on the line segment at the optimal point of communication time and performs data collection. In the second algorithm, the UAV hovers on the path length optimal locations and collects data by hovering. Algorithms are compared with time-sharing communication and single user scenarios. The results reveal that the trajectory design with multiple access communication optimal locations is better when the sensors are not too far apart and the packet lengths are long. On the other hand, path length optimal trajectory is better when the packet lengths are short.Günümüzde bilgiye erişim oldukça önemli bir ihtiyaçtır. Kablosuz haberleşme sistemlerinin çeşitli uygulamaları bu ihtiyacı karşılayabilmektedir. Son zamanlarda akademideki ve sanayideki çalışmalarda önemli yeri olan İnsansız Hava Araçları (İHA), insanların hayatlarını birçok alanda kolaylaştırdığı gibi kablosuz haberleşme alanında da çeşitli uygulamalar ile bilgiye erişimi kolaylaştırmaktadır. Bu tez kapsamında, bilgiye erişimin zaman açısından kritik uygulamalar için sensör ağlarında İHA destekli bir sistem ile yapılması incelenmiştir. İHA ile veri toplama, birçok pratik uygulamaya sahip yeni bir teknolojidir. İHA'nın topladığı verinin olabildiğince hızlı bir şekilde kullanılacağı veri merkezine getirilmesi gerekmektedir. Yapılan akademik çalışmalarda İHA'nın topladığı veriyi veri merkezine getirmesindeki gecikme, problemlere bilgi yaşı (Age of Information, AoI) parametresi ile amaç veya kısıt olarak girmektedir. Bu çalışmada bilgi yaşı, hem haberleşme süresinin hem de uçuş süresinin etki ettiği bir performans metriği olarak kullanılmaktadır. Literatürde çok fazla bulunan İHA'nın sensörleri teker teker gezip veri toplama işlemini gerçekleştirmesi fikri yerine, bu çalışmada sensörler gruplar halinde ele alınmıştır. Gruplandırma fikrinin performansa etkisini görmek için bu çalışmada ikili sensör grupları üzerinde çalışılmıştır. Veri merkezinden yola çıkan İHA, gruplardaki sensörler arasında oluşan doğru parçaları üzerinde bir noktada havada durarak çoklu erişim kanalı ile veri toplayıp ardından veri merkezine geri dönmeyi amaçlamaktadır. İkili sensör gruplarının oluşması ile İHA, her sensörü ayrı ayrı ziyaret etmeyeceğinden gideceği yörüngede daha kısa yol izleyebilecek ve çoklu erişim kanalı haberleşmesiyle daha kısa haberleşme sürelerine ulaşabilecektir. Sensörlerde biriken en yüksek bilgi yaşı parametresini en aza indirmek için iki yörünge tasarım algoritması önerilmiştir. Her iki algoritmada da İHA, çoklu erişim kanalı aracılığıyla her gruptaki sensörlerle iletişim kurar. İlk algoritmada İHA, doğru parçası üzerinde haberleşme süresi optimal noktada havada durur ve veri toplama işlemini gerçekleştirir. İkinci algoritmada, yol uzunluğu optimal noktalarda havada durarak veri toplamaktadır. Algoritmalar, zaman paylaşımlı haberleşme senaryolarıyla ve tüm sensörlerin ayrı ayrı ziyaret edildiği durumla karşılaştırılmıştır. Sonuçlar, sensörler birbirinden çok uzak olmadığında ve paket uzunlukları uzun olduğunda çoklu erişim haberleşmesine göre yörünge tasarımının optimal olduğunu, paket uzunlukları kısa olduğunda yol uzunluğu optimal yörüngesinin daha iyi olduğunu ortaya koymaktadır
Understanding and Predicting Characteristics of Test Collections in Information Retrieval
No full text17th International Conference on Information for a Better World: Shaping the Global Future, iConference 2022 -- 28 February 2022 through 4 March 2022 -- -- 273989Research community evaluations in information retrieval, such as NIST’s Text REtrieval Conference (TREC), build reusable test collections by pooling document rankings submitted by many teams. Naturally, the quality of the resulting test collection thus greatly depends on the number of participating teams and the quality of their submitted runs. In this work, we investigate: i) how the number of participants, coupled with other factors, affects the quality of a test collection; and ii) whether the quality of a test collection can be inferred prior to collecting relevance judgments from human assessors. Experiments conducted on six TREC collections illustrate how the number of teams interacts with various other factors to influence the resulting quality of test collections. We also show that the reusability of a test collection can be predicted with high accuracy when the same document collection is used for successive years in an evaluation campaign, as is common in TREC. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.Acknowledgments. We thank the reviewers for their valuable feedback. This research was supported in part by Wipro, the Micron Foundation, and by Good Systems (http://goodsystems.utexas.edu/), a UT Austin Grand Challenge to develop responsible AI technologies. The statements made herein are solely the opinions of the authors and do not reflect the views of the sponsoring agencies.Micron Foundatio
Seramik Sanatçılarının ve Endüstriyel Seramik Tasarımcılarının Seramik Eğitimine Yönelik Görüşleri
No full textBu araştırma ile seramik eğitimcilerinin, sanatçılarının ve endüstriyel seramik tasarımcılarının lisans düzeyinde seramik eğitimine ve bu eğitimin sanatsal ve endüstriyel uygulamalara katkılarına yönelik görüşlerinin değerlendirmesi amaçlanmıştır. Bu araştırma, 2021-2022 eğitim ve öğretim yılında uygulanan seramik eğitim programları konusunda görüşülen güzel sanatlar fakülteleri seramik bölümü öğretim elemanları, seramik alanında tasarımlarını gerçekleştiren tasarımcılar ve seramik sanatçıları ile sınırlı olmuştur. Araştırmada yöntem olarak nitel araştırma desenlerinden durum çalışması kullanılmıştır. Araştırmadan elde edilen bulgulara göre seramik eğitim programına ilişkin olumlu ve olumsuz durumlar belirlenmiştir. Bu durumlar seramik eğitim programında yer alan dersler, bu derslerin sayıca ağırlıkta olduğu alanlar, fiziki yeterlilik ve programların imkânları ile ilgilidir. Ayrıca eğitimci kadrosunun niteliği, bütçe imkânlarının sınırlılığı, yetersiz ekipman ve donanım, mezun istihdamında yaşanan sorunlar ortaya konulmuştur. Araştırmanın katılımcılarının görüşlerine göre, eğitim programı açısından seramik eğitimine yönelik kimi öğretim elemanı olumlu görüş bildirirken kimi öğretim elemanı da seramik eğitiminin olumsuz taraflarını dile getirmiştir. Seramik eğitiminde sanat ve tasarım alan seçimine yönelik görüşler de farklılaşmıştır. Bu araştırma göstermiştir ki, çok yönlü olması beklenen seramik eğitim programlarına ilişkin gerekli yenilikler ve düzenlemelerin yapılması hem öğrencilerin mezuniyetlerine ve istihdamlarına hem de seramik sektörüne olumlu katkılar sağlayabilecektir.This research, it is aimed to evaluate the opinions of ceramic educators, artists, and industrial ceramic designers on ceramics education at the undergraduate level and the contributions of this education to artistic and industrial applications. This research was limited to the lecturers of the ceramics department of the faculties of fine arts, designers, and ceramic artists who realized their designs in the field of ceramics and were interviewed about the ceramic education programs implemented in the 2021-2022 academic year. In the study, case study qualitative research patterns were used as a method. According to the findings obtained from the research, positive and negative situations related to the ceramic education program were determined. These situations relate to the courses in the ceramics education program, the areas where these courses are numbered, physical competence, and the opportunities of the programs. In addition, the quality of the educators, the limitation of budget opportunities, insufficient equipment, and the problems experienced in the employment of graduates were revealed. According to the opinions of the participants of the study, some instructors expressed a positive opinion about ceramics education in terms of the education program, while some instructors expressed the negative sides of ceramics education. Opinions on the choice of art and design field in ceramics education have also differed. This research has shown that making the necessary innovations and arrangements for ceramic education programs, which are expected to be multifaceted, will make positive contributions to both the graduation and employment of students and the ceramic sector
Investigation of the Loss Performance of the Spoof Surface Plasmon Polariton Waveguides at 1 Thz Band
No full textConference on Terahertz Photonics II Part of SPIE Photonics Europe Conference -- APR 03-MAY 20, 2022 -- ELECTR NETWORKThe terahertz imaging systems bring the advantage of both optical and microwave frequency spectrums, thanks to the invasion capability of the terahertz waves thru different media providing high-resolution imaging at real terahertz frequencies such as 1 THz. Nevertheless, the state-of-the-art terahertz technologies employ bulky optical system design approach. In consequence, the state-of-the-art terahertz systems are not suitable for high mobility terahertz imaging applications. On the other hand, the state-of-the-art terahertz integrated circuits (TICs) suffer from high attenuation due to conventional terahertz waveguides, and hence, a novel high-performance terahertz waveguide is needed. In this paper, we present the investigation of loss performance of Spoof Surface Plasmon Polariton (SSPP) waveguides (WGs) that operate at 1 THz, which will enable the demonstration of compact and high-performance TICs. We present a relationship between the corrugation dimensions, radiation, and metallic losses and guided wavenumber for the first time. The proposed SSPP WGs are able to transmit the terahertz wave in expense of an insertion loss of -4.93 dB thru 250 mu m at 1 THz.We acknowledge TUBITAK 119E489 for their financial support.SPIE,IdEx Univ Strasbourg,CNRS,ICube,Univ StrasbourgTUBITAK [119E489