Loss reduction in substrate integrated waveguide structures

A method for decreasing the loss in substrate integrated waveguide (SIW) structures is introduced. In this method, the dielectric substrate is partially removed. Accordingly, dielectric loss reduction has been explicated analytically. Its equivalence to the rectangular waveguide of solid walls which is partially filled with dielectric has been identified. A novel topology for demonstrating the idea is established and a low loss three port substrate integrated waveguide power divider is presented. This SIW power divider shows lower loss than conventional SIW power dividers. Proper TRL standards are realized for removing the effect of transition and/or matching sections in measurement process. For a low-loss three-port PSIW power divider, the return loss below 10 dB and transmission coefficients between -3 dB to -3.5 dB from 8.75 GHz to 10 GHz have been achieved. The measured amplitude imbalance is less than ±0.2 dB, and the measured phase difference between <S21 and <S31 is about 40 in the same frequency band

Space scanning FMCW-based two-dimensional frequency diverse array radar

The frequency-modulated continuous wave (FMCW)-based frequency diverse array (FDA) radar concept is extended to two dimensions (2D). The radar operates as a linear pulsed FMCW/FDA in the transmission (TX) mode while it operates as a pulsed FMCW/phased array (PA) in the receiving mode. It is shown that the FDA has the capability of scanning a 2D angular sector in a single pulse TX. It is shown that local instantaneous frequency bandwidth is much smaller than the radiofrequency (RF) frequency deviation of linear frequency modulation. Positive and negative slope TX/RF locations offer frequency diversity. The low signal-to-noise ratio of FDA is well compensated due to target temporal decorrelation diversity in the observation time and by the cumulative detection scheme used. Time domain and frequency domain signal processings are described. A Kuband direct digital synthesis-based FDA radar design is compared by a corresponding equivalent PA radar

Prospects of FMCW-based frequency diverse array radar

The linear frequency modulated (LFM) frequency modulated continuous wave (FMCW)-based frequency diverse array (FDA) radar concept is investigated in detail. The radar operates as a linear pulsed FMCW/FDA in the transmission (TX) mode while it operates as a pulsed FMCW/phased array (PA) in the receiving mode. The issues such as low signal-to-noise ratio (SNR) of FDA, the time-angle scanning and time-range ambiguities are studied. It is shown that the local instantaneous frequency bandwidth is much smaller than the radio frequency (RF) deviation of LFM. Positive and negative slope TX/RF locations offer frequency diversity. Time domain and frequency domain signal processings are described. A Ku band direct digital synthesis-based FMCW/FDA radar example based on the cumulative detection scheme is given and compared with an equivalent FMCW/PA radar

Towards prioritizing vulnerability testing

Vulnerability assessment is the process of identifying and prioritizing the vulnerabilities in a system. Vulnerability scanners can, for example, scan a website for known vulnerabilities by running a repository of security tests, each of which is designed to reveal a known vulnerability. As the security tests need to be executed on each and every web page encountered, it may take quite a while for these scanners to report vulnerabilities. In this work, we present an approach for revealing the vulnerabilities faster by prioritizing the executions of the security tests on a per web page basis. The approach is based on a simple conjecture that 'similar' web pages may possess 'similar' vulnerabilities and that identifying these similarities can help prioritize the security tests. The results of the experiments we carried out by using 2927 distinct web pages (collected from 80 web sites), support our basic hypothesis; the percentages of the times the actual vulnerabilities appear in the top 8 and 15 predicted vulnerabilities were 86.9% and 98.4%, respectively

Mikoriza uygulaması ve farklı sulama seviyelerinin geç dönemde yetiştirilen hıyarın verim ve verim bileşenleri üzerine etkisi

Mikoriza kök mantarı olarak adlandırılmakta ve kök korteksi içinde kolonize olarak çok sayıda lif üretmektedir. Üretilen bu lifler ile kök yüzey alanı genişlemekte ve bitkinin normalde alamayacağı uzaklıktaki su ve besin elementlerini alarak bitkiye ulaştırmaktadır. Bu çalışmanın amacı, mikoriza uygulamasının farklı sulama seviyelerinde hıyar bitkisinin verim ve verim bileşenleri üzerine etkisinin belirlenmesidir. Şanlıurfa ilinde 2017 yılı geç dönemde (ağustosekim) yürütülen bu araştırma, tesadüf blokları bölünmüş parseller deneme desenine göre 3 tekerrürlü olacak şekilde kurulmuştur. Ana parsel mikoriza uygulaması, alt parseller ise sulama suyu seviyelerinden (Kcp1:0.66, Kcp2:1.00 ve Kcp3:1.33) olmuştur. Sulama suyu miktarı A sınıfı buharlaşma kabına göre hesaplanmış ve damla sulama yöntemi ile parsellere uygulanmıştır. Araştırmadan elde edilen sonuçlara göre, hıyar bitkisine güz dönemde uygulanan sulama suyu miktarı 334-673 mm, bitki su tüketim değerleri ise 379-685 mm arasında değişmiştir. Hıyar bitkisinin verimi 20.54 t ha-1 ile 33.66 t ha-1 arasında gerçekleşmiştir. En yüksek verim mikoriza uygulamasının yapıldığı ve sulama suyu ihtiyacının %133’ünün karşılandığı konudan elde edilmiştir. Meyve çapı, meyve boyu ve meyve ağırlığı değerleri; sırasıyla 29-36 mm, 134-161 mm ve 103-135 g arasında ölçülmüştür. Çalışma sonucunda, mikoriza ve sulama uygulamasının hıyar bitkisinin verim ve verim parametreleri üzerinde önemli bir etkiye sahip olduğu tespit edilmiştir

Diagnosis, treatment and prevention of infective endocarditis: Turkish consensus report-2019 [İnfektif endokarditin tanısı, tedavisi ve önlenmesi: Ulusal uzlaşı raporu-2019]

Infective endocarditis (IE) is a rare but still important as an infectious disease due to high rate of morbidity and substantial mortality. Although IE is not a notifiable disease in Turkey, and an incidence study has not been performed, the incidence may be higher than that in the developed countries due to frequent predisposing cardiac conditions and higher rates of nosocomial bacteremia, which may lead to IE in risk groups. IE generally affects the elderly in developed countries but it is frequently encountered among young individuals in Turkey. In order to reduce mortality and morbidity, it is critical to diagnose IE, to determine the causative agent, and to start treatment rapidly. Most patients cannot be diagnosed at the first visit, about half can be diagnosed after 3 months, and the disease often goes unnoticed. In patients diagnosed with IE, the rate of the identification of a causative organism is significantly lower in Turkey than that in developed countries. Some important microbiological diagnostic tests are not performed in most centers and several antimicrobials that are recommended as the first option for the treatment particularly antistaphylococcal penicillins, are unavailable in Turkey. These problems necessitate reviewing the epidemiological, laboratory, and clinical characteristics of IE in our country, as well as the current information about its diagnosis, treatment, and prevention together with local data. The diagnosis and treatment processes of IE should be standardized at every stage so that the management can be conducted in a setting in which physicians of various specialties are involved and is consistent with the current recommendations. The Study Group for Infective Endocarditis and Other Cardiovascular Infections of the Turkish Society of Clinical Microbiology and Infectious Diseases called for the collaboration of the relevant specialist organizations to establish a consensus report on the diagnosis, treatment, and prevention of IE in the context of current information and local data in Turkey. © 2020 Turkish Society of Cardiology

Evaluation of Using Prenatalcare Services in Outpatients Applying to Gynecology and Obstetric Polyclinic

Purpose: Antenatal care, one of the strategies aimed at protecting maternal and child health, is to monitor the mother by trained health personnel at regular intervals throughout pregnancy. This study aimed to evaluate the prenatal care service use of pregnant women who attend Kartal Dr. Lütfi Kırdar City Hospital Gynecology and Obstetrics Polyclinics. Materials and Methods: The sample universe of this cross-sectional study was pregnant women attending Kartal Dr. Lütfi Kırdar City Hospital Gynecology and Obstetrics Polyclinic between 01.08.2020-01.09.2020. The questionnaire developed by the researchers was applied to the participants by face-to-face interview technique. Results: All the participants (n=403) received at least one prenatal care service from a health institution. 73.4% (n=296) of the pregnant women received prenatal care, which is required according to their weeks of gestation quantitatively. The highest rate of physical examination in antenatal care follow-ups was fetal heart rate, while the lowest rate was the cardiac auscultation and edema examination rates of the pregnant woman. Conclusion: It was seen that all of the pregnant women received antenatal care at least once, but the number of prenatal care follow-ups required in accordance with their gestational weeks was still not at the desired level. For this reason, there is a need for a study to determine the factors that prevent compliance with the follow-ups and to carry out the ideal four follow-ups of all pregnant women

Apandisit ile komplike gebeliklerin cerrahi tedavisi ve gebelik sonuçları: obstetrisyen görüşü

Objective: To evaluate the pregnancy outcomes of patients who underwent appendectomy during pregnancy. Materials and Methods: Patients who underwent appendectomy between years 2010 and 2014 were retrospectively evaluated. All patients’ pregnancy outcomes were followed-up by using university registry system and telephone interview. Patients were evaluated regarding age, gestational age, clinical and laboratory examinations, imaging studies, mean time interval between emergency department and operation, mean operative time, pregnancy outcome and pathologic results of the appendix. Results: Thirty-nine patients were included in the study. Sixteen of 39 patients were in the first, 15 of them in the second and 8 of them were in the third trimester of the pregnancy. Three patients underwent laparoscopic appendectomy and the rest underwent laparotomy. In pathologic evaluation of the appendix, seven patients (17%) had normal appendix, 4 patients had perforated appendix, one patient had neuro-endocrine tumor and rest of the patients had appendicitis. Two missed abortion occurred after operation, rest of the patients had live birth. Six of them were preterm and 31 had term birth. Twelve patients delivered through vaginal birth and the rest via caesarean section. Twenty patients were in the first half of the pregnancy (group 1) and 19 patients were in the second half of the pregnancy (group 2). There were no significant differences between the groups in operation time and mean time interval between emergency administration and operation. Conclusion: Delayed operation and negative appendectomy can cause adverse pregnancy outcomes. Expectant management in suspected cases may decrease negative appendectomy rates but can also lead to perforation. Computed tomography and MRI ought to be considered if ultrasonography is inconclusive. Tocolytic regimens can be administered to prevent threatened preterm labor. Obstetric indications were valid for delivery mode.Amaç: Gebeliğinde apendektomi yapılan hastaların gebelik sonuçlarının değerlendirilmesi. Gereç ve Yöntemler: 2010-2014 yılları arasında apendektomi yapılan hastalar retrospektif olarak incelendi. Tüm hastaların gebelik sonuçları üniversite kayıt sistemi ve telefon görüşmeleri ile takip edildi. Hastalar yaş, gebelik yaşı, klinik ve laboratuvar muayeneleri, görüntüleme çalışmaları, acil servis ve operasyon arasındaki ortalama zaman, ortalama operasyon süresi, gebelik sonucu ve apandiksin patoloji sonucuna göre değerlendirildi. Bulgular: Otuz dokuz hasta çalışmaya dahil edildi. Otuz dokuz hastanın 16’sı ilk, 15’i ikinci ve 8’i gebeliğin üçüncü trimesterindeydi. Üç hastaya laparoskopik apendektomi kalanlarına laparatomi yapıldı. Apendiksin patolojik değerlendirilmesinde, yedi hasta (17%) normal apendiks, dört hasta perfore apendiks, bir hasta nöro-endokrin tümor ve kalanları apandisit saptandı. Operasyon sonrası iki missed abortus meydana gelirken kalanları canlı doğum yaptı. Bunlardan altısı preterm ve otuz biri term doğum yaptı. On iki hasta vajinal yolla ve kalanları sezaryen yoluyla doğurtuldu. Yirmi hasta gebeliğin birinci yarısında (grup 1) ve 19 hasta gebeliğin ikinci yarısındaydı (grup 2). Gruplar arasında operasyon zamanı ve acile kabul ile operasyon arasındaki ortalama zaman aralığı açısıdan anlamlı farklılık yoktu. Sonuç: Gecikmiş operasyon ve negatif apendektomi olumsuz gebelik sonuçlarına neden olabilir. Şüpheli olgulardaki izlem tedavisi negatif apendektomi oranlarını düşürebilir; ancak aynı zamanda perforasyona neden olabilir. Bilgisayarlı tomografi ve manyetik rezonans görüntüleme, ultrasonografinin net olmadığı zaman düşünülmelidir. Erken doğum tehditini önlemek için tokolitik rejimler uygulanabilir. Doğum şekli için obstetrik endikasyonlar geçerlidir

Bilgi toplumu teknolojileri için anten sistemleri ve algılayıcılar

TÜBİTAK EEEAG01.10.2010Bu proje kapsamında, özellikle milimetre-dalga frekanslarında çalışan yeniden şekillendirilebilir anten, elektronik taramalı dizi anten ve yansıtıcı dizi anten tasarımı, üretimi ve ölçümleri yapılmıştır. Yeniden şekillendirilebilirlik özelliği için farklı teknolojiler kullanılmıştır. Huzmesi yönlendirilebilen sur biçimli mikroşerit yürüyen dalga anten dizisi X-bant uygulamalarında kullanılmak üzere tasarlamış, üretilmiş ve ölçülmüştür. Antenin ana huzmesinin istenilen yöne elektronik olarak döndürülebilmesini sağlayabilmek için mikroşerit hat üzerinde gerekli faz değişimini sağlayacak varaktör diyotlar kullanılmıştır. Yapılan EM benzetim ve ölçümler sonucu sur biçimli anten dizisinde, ana huzmenin diyot kontrolü ile tasarlandığı gibi 10 lik bir açı taraması yapabildiği gösterilmiştir. Bu kavram kanıtlaması şeklinde bir çalışmadır; huzmenin daha büyük açı aralığında tarama yapması için tasarımda yapılması gereken değişiklikler belirtilmiştir. MM-Dalga sabit genişlikli ve doğrusal sönümlenen yarık antenler tasarlanıp, üretilmiş ve antenin şeklinin, optik uyarımla bu iki yapı arasında değiştirilmesinin sağlanması durumunda ışıma örüntüsünün değiştirilebileceği gösterilmiştir. Proje kapsamında gerçekleştirilen bir diğer çalışmada da K ve Ka bantlarında bağımsız çalışabilen, RF MEMS anahtarlarla huzmesi elektronik olarak döndürülebilen dairesel polarizasyonlu yansıtıcı dizi anten tasarlanmış, üretilmiş ve ölçülmüştür. Çift frekanslı (24.4 GHz ve 35.5 GHz) dizi iç içe geçmiş farklı boyutlarda iki ayrık-halka dizisi şeklinde tasarlanmıştır. Huzme döndürme amacıyla her bir ayrık halkanın açısal konumunu RF MEMS anahtarlarla ayarlayarak, dairesel polarizasyonlu dalgaların fazları kontrol edilmektedir. Anten ODTÜ MEMS merkezinde geliştirilen yüzey mikro-işleme süreciyle üretilmiştir. Işıma örüntüleri ölçülmüş ve benzetim sonuçlarıyla karşılaştırılmıştır. Ölçümlerle, ana huzmenin, tasarlandığı gibi, Ka bandında 35°‟ye, K bandında 24°‟ye döndürülebildiği gösterilmiştir. Proje çalışmalarından sur biçimli mikroşerit anten dizisiyle ilgili hazırlanan makale Microwave and Optical Technology Letters adlı dergide yayınlanmak üzere kabul edilmiştir. Yansıtıcı dizi antenle ilgili makale de hazırlık sürecindedir. Saygın konferanslarda yedi bildiri sunulmuştur. Ayrıca, proje kapsamında üç yüksek lisans tez çalışması tamamlanmıştır.In this project, reconfigurable antenna, beam steering array and reflectarray have been designed, produced and measured, especially in mm-wave frequencies. To provide reconfigurability, different technologies have been considered. X-band electronically scanning meanderline microstrip traveling wave antenna array has been designed, produced and measured. To rotate the antenna beam to the desired direction, microstrip meander line has been loaded by varactor diodes that provide required phase shift values. EM simulations and rdiation pattern measurements of the meanderline antenna have demonstrated that the antenna has the capability to scan 10 with the control of varactors as designed. This is a proof-of-concept type study; alternative configurations to increase the scan range have also been discussed. MM-wave tapered slot antennas with a constant width and linear taper have been designed, produced and measured. It has been demonstrated that if the shape of the tapered slot antenna can be changed between constant width and linear taper structures by means of optical excitation, radiation pattern reconfigurability can be obtained. In another study accomplished in this project, electronically scanning circularly polarized reflectarray working independently in K and Ka bands has been designed, produced and measured. Dual band (24.4 GHz and 35.5 GHz) reflectarray has been designed as an interlaced array of split rings of two different sizes. In order to steer the beam, the phase of the incident circularly polarized wave is controlled by RF MEMS switches that modify the angular orientation of split-rings individually. The antenna has fabricated by using surface micromachining process developed in METU MEMS Center. Radiation patterns of the antenna are measured and compared with the simulations. It has been shown that the reflectarray is capable of beam switching to 35° in Ka band, 24° in K band as required. One journal paper on meanderline antenna has been accepted to be published in Microwave and Optical Technology Letters. Preparation of manuscript on reflectarray is under progress. Seven conference papers have been presented in well known Conferences. Furthermore, three Master Thesis studies have been accomplished during the project