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It was aimed to reveal the continuing perfusion defect rates in patients with a diagnosis of pulmonary embolism (PE) due to COVID-19 who have completed the third month of anticoagulant therapy but whose symptoms or laboratory elevations continue.Patients with COVID-19 who were diagnosed with PE by Q-SPECT-CT between 1 September 2020 and 1 November 2021, who underwent control Q-SPECT/CT were included in the study. Demographic characteristics, laboratory findings, and first and second Q-SPECT/CT evaluation results of the patients were recorded.It was observed that the pulmonary defect continued in Q-SPECT/CT in the third month of anticoagulant treatment in 58.3% of the patients diagnosed with PE due to COVID-19, and new defects developed in 6.3%. The persistence rate of segment defects was higher than that of subsegment defects. It was observed that the defects persisted more frequently in patients with a history of hospitalization due to COVID-19.Perfusion defects may still be present in patients diagnosed with PE due to COVID-19 in the presence of persistent dyspnea/chest pain/D-dimer elevation after 3 months of treatment. Perfusion defect persistence rates are higher in defects more proximal to the subsegment level and in people with severe COVID-19, and extended treatment should be considered in these patients.

Bu çalışmada, Otonom Mobil Robotların (OMR) dönüşleri esnasında hareket doğrultusunda meydana gelen sapmalara avare tekerlerin etkisi incelenmiştir. Avare tekerlerin sürüş etkilerinin incelenmesi için CoppeliaSim programında bir OMR’nin analizi yapılmıştır. CAD programında tasarımı yapılan avare tekerleklerin Unified Robot Description Format (URDF) dosyası CoppeliaSim programına aktarılmıştır. OMR’nin ağırlığının dönüşlere etkisini incelemek için toplamda 75 ve 150 kg olmak üzere iki farklı ağırlıkta OMR kullanılmıştır. Analizlerde tekli, çiftli ve çift eksenli olmak üzere 3 farklı avare teker çeşidi kullanılmıştır. Avare tekerler arasında kıyaslama yapabilmek için diğer parametreler olan avare tekerin çapı, dönme ekseni ve toplam yüksekliği her bir durum için sabit tutulmuştur. Elde edilen sonuçlara göre, tekli avare tekerler dönüşlerde en fazla sapmaya neden olmaktadır. Çiftli avare tekerlerdeki sapmalar, tekli avare tekere göre daha düşük değerlerdedir. Bunula beraber, en düşük sapma miktarı çift eksenli avare tekerlerde olmaktadır. Ayrıca, çift avare teker ve çift eksenli avare teker bulunan OMR’lerde meydana gelen sapmalar tekli avare tekere oranla OMR’nin ağırlığından çok fazla etkilenmemektedir.

Bu çalışmada operatör ve sürücüye ihtiyaç duymadan otonom bir şekilde fabrika ve endüstriyel tesislerde yükün bir yerden alınarak başka bir yere taşınması işlevini gerçekleştiren Otonom Mobil Robot (OMR)’nin tasarım ve analizi yapılmıştır. OMR’lerin özellikle operatör ve sürücüye ihtiyaç duymaması gibi özellikleri onlara geniş bir kullanım alanı sağlamıştır. Bu çalışma için özgün bir OMR tasarımı gerçekleştirilmiştir. Tasarımı yapılan OMR’nin 1000, 1500 ve 2000 kg yük altında meydana gelen deformasyon ve gerilme analizi yapılmıştır. Tasarım gerçekleştirilirken OMR’nin taşıyıcı şasesinde meydana gelen deformasyon ve gerilmenin yükten bağımsız olması özelliği düşünülmüştür. Elde edilen analiz sonuçları ile tasarımın bu özelliği sağladığı simülasyon yardımıyla ispatlanmıştır. Her üç yük için de analiz sonuçlarında şasenin dayanımı yaklaşık aynı çıkmıştır. Böylece, taşıyıcı şasenin boyutları ve yapısından bağımsız olan ve yalnızca taşıyıcı tekerlerin toplam kapasitesi kadar yük taşıyabilen bir OMR elde edilmiştir.

In this study, the storage of solar energy as thermal energy is experimentally examined. A special heat storage unit is designed to store solar energy in liquid, stones and phase change material. Water, basalt stones, paraffin and air were used as the liquid, stones, phase change material and heat transfer fluid, respectively. Unlike classical designs, a glass cover is used for the heat storage unit, which receives direct solar radiation from the southern facade. Thus, the effect of the direct contact of the solar radiation with the stones on the performance of the heat storage unit is investigated. In the heat storage unit, if the sun does not directly reach the stones, the maximum temperature of the stones that can be reached is 46.6 & nbsp;? whereas when the sun hits the stones directly, a maximum temperature of 56.8 & nbsp;? can be achieved. It is suggested that an average of 50.3% of the energy requirement for heating from sunset to sunrise, depending on the weather conditions of the days of the exper-iments can be obtained using the solar energy heat storage unit designed in this study.

The movement of a single air bubble on an inclined hydrophobic surface submerged in water, including both the upward- and downward-facing sides of the surface, was investigated. A planar Teflon sheet with an apparent contact angle of a sessile water droplet of 106 degrees was used as a hydrophobic surface. The volume of a bubble and the inclination angle of a Teflon sheet varied in the ranges 5-40 mu L and 0-45 degrees, respectively. The effects of the bubble volume on the adhesion and dynamics of the bubble were studied experimentally on the facing-up and facing-down surfaces of the submerged hydrophobic Teflon sheet, respectively, and compared. The result shows that the sliding angle has an inverse relationship with the bubble volume for both the upward- and downward-facing surfaces. However, at the same given volume, the bubble on the downward-facing surface spreads over a larger area of the hydrophobic surface than the upward-facing surface due to the greater hydrostatic pressure acting on the bubble on the downward-facing surface. This makes the lateral adhesion force of the bubble greater and requires a larger inclination angle to result in sliding.

Bu çalışmada, panel radyatörlerarkasına konulan ışınım yayma katsayıları farklı değerlerde olan malzemelerinısıl verime etkisi deneysel olarak incelenmiştir. Deneylerde 3 cm cam yünüüzerine yapıştırılmış ışınım yayma katsayısı düşük değerde (0,9) olan siyahboya ile boyanmış alüminyum folyo yüzeyler kullanılmıştır. Radyatör sıcaklığı45 ve 55°C olarak alınmış ve yüzey ile radyatör arasında 6 cm aralık olacakşekilde deneyler gerçekleştirilmiştir. Deneylerde ısıl çiftler kullanılarakradyatör ve yansıtıcı/yutucu yüzey üzerinde farklı yükseklik ve mesafelerdekisıcaklıklar ölçülmüştür. Yapılan deneyler sonucunda, yutucu yüzeykullanıldığında yutucu (mat siyah) yüzey sıcaklığının yansıtıcı (parlak)yüzeyden yaklaşık %15 oranında daha fazla olduğu tespit edilmiştir. Bununyanında yansıtıcı yüzey kullanılması durumunda ise radyatör yüzeyine yakınbölgenin sıcaklığının yutucu yüzey kullanılarak elde edilen sıcaklığa göreyaklaşık %7 oranında daha yüksek olduğu tespit edilmiştir., In this study, an experimental investigation has been performed to examinethe effect of the emissivity of the wall, placed behind the radiator. Analuminium and a sprayed aluminium folios with black paint walls were used inthe experiments. The folios with a low emissivity (0.9) were placed on the glass wools with 3 cmthick. The experiments were performed for the radiator temperatures of 45 and55 °C, respectively. The interval between the radiator and wall was 6 cm. Thetemperatures at the different points on the radiator and reflector/absorberwalls were measured. The results suggested that the temperature of the absorbersurface is about %15 higher than the reflector surface. Besides the temperatureof the region close to the radiator surface is about %7 higher in the case ofexperiment using the reflector wall, than that case of using absorber wall.

In this study, the behaviour of an inclined water jet, which is impinged onto hydrophobic and superhydrophobic surfaces, has been investigated experimentally. Water jet was impinged with different inclination angles (15°–45°) onto five different hydrophobic surfaces made of rough polymer, which were held vertically. The water contact angles on these surfaces were measured as 102°, 112°, 123°, 145° and 167° showing that the last surface was superhydrophobic. Two different nozzles with 1.75 and 4 mm in diameters were used to create the water jet. Water jet velocity was within the range of 0.5–5 m/s, thus the Weber number varied from 5 to 650 and Reynolds number from 500 to 8,000 during the experiments. Hydrophobic surfaces reflected the liquid jet depending on the surface contact angle, jet inclination angle and the Weber number. The variation of the reflection angle with the Weber number showed a maximum value for a constant jet angle. The maximum value of the reflection angle was nearly equal to half of the jet angle. It was determined that the viscous drag decreases as the contact angle of the hydrophobic surface increases. The drag force on the wall is reduced dramatically with superhydrophobic surfaces. The amount of reduction of the average shear stress on the wall was about 40%, when the contact angle of the surface was increased from 145° to 167°. The area of the spreading water layer decreased as the contact angle of the surface increased and as the jet inclination angle, Weber number and Reynolds number decreased.

In this study, the flow characteristics of an impinging circular liquid jet on a superhydrophobic surface are examined both experimentally and numerically. A computational fluid dynamics (CFD) program was used for comparison in terms of experimental results, and data from the literature was used to reveal phenomena related to the spreading and reflection of a liquid jet from a superhydrophobic surface. A piece of Brassica oleracea leaf with an apparent contact angle of 160° was used as a superhydrophobic surface. A circular glass tube of 1.75 mm inner diameter was used to produce a liquid jet. The Weber number, Reynolds number and the inclination angles of the liquid jet were varied in the ranges of 20–105, 1,700–3,800 and 20°–40°, respectively. The results indicate that the numerical predictions obtained using the CFD program seem to show good agreement with the experimental data in terms of explaining the phenomena of the flow (spreading, reflection, etc.) in all cases, and in providing more detailed information about the spreading and reflection of a liquid jet on a superhydrophobic surface.

Experiments and numerical simulations were carried out to examine the vertical impingement a round liquid jet on the edges of horizontal convex surfaces that were either superhydrophobic or hydrophobic. The experiments examine the effects on the flow behaviour of curvature, wettability, inertia of the jet, and the impingement rate. Three copper pipes with outer diameters of 15, 22, and 35 mm were investigated. The pipes were wrapped with a piece of a Brassica oleracea leaf or a smooth Teflon sheet, which have apparent contact angles of 160° and 113°. The Reynolds number ranged from 1000 to 4500, and the impingement rates of the liquid jets were varied. Numerical results show good agreement with the experimental results for explaining flow and provide detailed information about the impingement on the surfaces. The liquid jet reflected off the superhydrophobic surfaces for all conditions. However, the jet reflected or deflected off the hydrophobic surface, depending on the inertia of the jet, the curvature of the surface, and the impingement rate. The results suggest that pressure is not the main reason for the bending of the jet around the curved hydrophobic surface.

This study presents the theory of impinging an oblique liquid jet onto a vertical superhydrophobic surface based on both experimental and numerical results. A Brassica oleracea leaf with a 160° apparent contact angle was used for the superhydrophobic surface. Distilled water was sent onto the vertical superhydrophobic surface in the range of 1750–3050 Reynolds number, with an inclination angle of 20°−40°, using a circular glass tube with a 1.75 mm inner diameter. The impinging liquid jet spread onto the surface governed by the inertia of the liquid and then reflected off the superhydrophobic surface due to the surface energy of the spreading liquid. Two different energy approaches, which have time-scale and per-unit length, were performed to determine transformation of the energy. The kinetic energy of the impinging liquid jet was transformed into the surface energy with an increasing interfacial surface area between the liquid and air during spreading. Afterwards, this surface energy of the spreading liquid was transformed into the reflection kinetic energy.