Sakarya University of Applied Sciences AXSIS
Not a member yet
2251 research outputs found
Sort by
Synthesis, Structural and Radiation-shielding Properties of Li2O-Al2O3-SiO2 Glass–ceramic System
No full textThe Li2O-Al2O3-SiO2 (LAS) glass system has high commercial values due to its very low thermal expansion coefficients and its very high chemical resistance among other properties. In this study, the preparation of LAS-based glass–ceramics (G-Cs) is reported, and the influence of P2O5 as a nucleating agent for crystallizing the amorphous glass structure at different rates into this glass composition, on the physical, structural, and mechanical properties is presented. The influece of different crytalization temperature on the crystal size and micreostructure as well as the radiation absorption abilities of the G-Cs were also investigated. The G-Cs were prepared using the melt and quench method and subjected to different temperature regimes to crystallise. The crystallinity of the prepared samples was examined with the aid of X-ray Diffraction analysis, while their chemical composition was probed using energy dispersive spectroscopy (EDS). The mass attenuation coefficients (MACs) of the samples were estimated for 15 keV–15 MeV photons using the well-known WinXCom software. Lithium silicate with the main phase formulation Li0.75Al0.75Si2.25O6 was identified as the main crystalline phase within the residual glass phase. The increase in P2O5 content slightly diminishes the photon absorption abilities of the G-Cs. However, the G-Cs showed better photon absorption prowess compared to some notable shielding materials. The G-Cs are thus important shielding materials useful for radiation control purposes. © The Author(s), under exclusive licence to Springer Nature B.V. 2024
Esnek bütçe kısıtı sorunsalı: Türkiye yerel yönetimleri örneği
No full textEsnek bütçe kısıtı olduğu durumda devletin destek verdiği kurum ve kuruluşlar harcamalarını artırma eğiliminde olabilirler. Merkezi yönetim, yerel yönetimlerdeki açığın tamamını veya bir kısmını karşılamaya hazır olduğunda, esnek bütçe kısıtlaması ortaya çıkmaktadır. Yerel yönetimler mali sıkıntılarının giderilmesini fırsat olarak görebilirler. Mali kurtarma beklentisi davranışı süreklilik kazanabilir. Bu beklenti onların karşılayabileceğinden daha fazlasını harcamalarına neden olur. Yapılması gereken yerel yönetimlerin öz gelir elde etme çabalarının artmasını sağlama yolunda adımlar atılmasını sağlamaktır. Merkezi yönetim, herhangi bir olumsuz mali durum yaşanması halinde yardım etmeyeceğini belirtmesi gerekir. Böylece yerel yönetimler kazanç elde etme yollarına yöneleceklerdir. Bu nedenle bütçe kısıtını esneten değil, bütçe kısıtını katılaştıran uygulamalar harcama yapmalarının önüne geçebilir. Türkiye'deki çalışmaların yerel yönetimleri daha çok mali özerklileri açısından değerlendirdikleri görülmüştür. Bu çalışmada bütçe kısıtlamasını esneten ve yerel yönetimlerin beklenti ve davranışlarına yön veren faktörler ve araçlar bağlamında yerel yönetimler değerlendirilmiştir. Bu anlamda akademik literatüre katkı sağlayacağı düşünülmektedir. Bu çalışmanın amacı merkezi yönetimin hangi durumlarda yerel yönetimlerin yükümlülüklerine kefil olacağını, yerel yönetimlerin niçin öz gelir yaratma konusunda isteksiz olduklarını ve mali ve siyasi kurtarma beklentisi içine girdikleri durumları tespit etmektir. Yöntem olarak yabancı ve yerli literatür araştırılmıştır. Çalışmanın bulgularına göre Türkiye’de merkezi yönetimin yerel yönetimlere yapılan transferleri kısabilmesi için yasal bir değişiklik yapılması gerekir. Yerel yönetimlerin vergi, resim, harç ve benzeri zora dayanan yerel gelir kalemleri üzerinde tasarruf yetkileri sınırlı olduğu için bu kaynaklardan etkin bir şekilde yararlanamamaktadırlar
Gamma attenuation, dose rate and exposure/absorption buildup factors of apatite–wollastonite (AW) ceramic system
No full textApatite-wollastonite (AW) is an important biomaterial useful in clinical practice for tissue engineering and other applications. In this research paper, AW and B2O3-doped AW glass ceramics (GCs) were reported and investigated deeply by means of their ability to attenuate gamma-photons. The studied samples denoted by AW, AW-10B, and AW-20B as the B2O3 content from 0 to 20 mol% with the step of 10. Using FLUKA and other theoretical approaches, photon interaction parameters for narrow and broad beam transmission through the AW GCs were estimated for the 15 keV–15 MeV energy range. Also, the density of the GCs increased as the B2O3 content increased. The mass attenuation coefficients were found to be within the ranges 0.0231–13.5659 cm2/g, 0.0225–12.3561 cm2/g, and 0.0220–11.1079 cm2/g for AW, AW-10B, and AW-20B, respectively. The effective atomic number of the GCs fell within the range 11.04–17.26, 10.88–17.01, and 10.21–16.72, respectively. As the doping concentration of B2O3 increased, the gamma energy that the AW GCs were able to absorb decreased. The addition of B2O3 compromised the photon shielding competence of AW in both narrow beam and broad beam scenarios. The GCs had better photon-absorbing competence than some existing gamma-photon shields. The GCs may thus be used as photon absorbers in clinical practice or in other nuclear applications. © 202
A comparative study: incremental sheet forming of AA1050 by roller-ball tool and standard tool with its optimization
No full textIn this work, a single point incremental forming method was applied using both a roller-ball tool and a standard forming tool with oil application. Aluminium AA1050 sheet with 0.8-mm thickness was used as the experiment material. The experiments were applied according to Taguchi L18 experimental design. Surface roughness measurements and thickness distributions were evaluated in terms of tool type, amount of the stepdown and the wall angles. ANOVA and regression analysis were also performed to show the influence of the process parameters on the surface roughness measurements. According to results, roller-ball tool with a wall angle of 40 degrees and stepdown amount of 0.25-mm yielded the lowest surface roughness as 1.389-mu m for Ra and 7.433-mu m for Rz. Compared to the standard forming tool, the roller-ball tool performed better both surface roughness and thickness distribution results. However, the most effective parameter was found to be the wall angles in relation to the surface roughness. FEM analysis was made for thickness distributions with the same process conditions for each tool type. The actual measurements for thickness distribution were similar to the results obtained from FEM analysis
Thermal and Mechanical Vibration Response of Auxetic Core Sandwich Smart Nanoplate
No full textThis study explores a new nanoplate design's thermal and mechanical properties, including an auxetic core with a negative Poisson ratio. The core is between face plates made of barium–cobalt, which possess magnetoelectroelastic properties. The analysis centers on the parameters θ, β1, and β2 to clarify their influence on the nanoplate's performance. The evaluations of the nanoplate's thermal, electrical, and magnetic properties showcase its remarkable versatility and sensitivity. Incorporating magnetoelectroelastic face plates improves the multifunctionality of the nanoplate, making it a highly promising option for use in smart technologies. The findings offer valuable insights into the distinctive features of auxetic core structures, significantly enhancing the comprehension of these materials. This research emphasizes the potential for creating groundbreaking applications in fields like aerospace engineering and advanced electronics, where versatile and adaptable materials play a vital role. This study contributes to the broader knowledge of auxetic materials and their practical implementation in cutting-edge technological solutions by exploring the interplay between thermal, mechanical, and magnetoelectroelastic properties. © 2024 The Author(s). Advanced Engineering Materials published by Wiley-VCH GmbH
Cost effective detection of uneven mounting fault in rotary wing drone motors with a CNN based method
No full textRotary wing drones stand out among Unmanned Aerial Vehicles with their vertical landing and take-off feature and are used in many industrial applications and different sectors. Ensuring the stability of motion in these vehicles is crucial. Errors in the motor assembly can disrupt the stability of the motion in rotary wing drones. Therefore, it is essential to detect these errors during the assembly phase. In this study, we propose a cost-effective method based on deep learning to detect assembly failure of brushless direct current motors, which are widely used in rotary wing drones. A test setup representing the motor assembly defects is created and vibration data for three different speeds of the motor are obtained through a low-cost vibration sensor. The combined one- and two-dimensional deep convolutional neural network (WDD-CNN), used to classify these data was trained with the Case Western Reserve University (CWRU) dataset and the data collected in this study. The hyper-parameter settings of the network were determined using the CWRU data set and the data obtained from the experimental setup described in the paper. The network parameters of the WDD-CNN network were transferred to the Raspberry Pi micro-controller with specialized software, and the classification process was performed there. The fact that the proposed method runs on a micro-controller reduces its cost. Because there is already a micro-controller card in drones. In addition, the selected sensor is cost-effective. Thanks to these features, the proposed method is cost effective. In this classification process performed on Raspberry Pi 5, assembly errors were detected with 97–100% accuracy. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024
Determining the Difficulties of Parents with Children in Home Care Who Were Discharged from Intensive Care; [Çocuğu Yoğun Bakımdan Taburcu Edilen Ebeveynlerin Evde Bakımda Yaşadıkları Güçlüklerin Belirlenmesi]
No full textIntroduction: This study was performed to determine the difficulties experienced by parents with children in home care who were discharged from intensive care. Methods: A phenomenological qualitative method was used to determine the difficulties experienced by the parents. The sample of the study consisted of parents (n=22) whose children met the inclusion criteria and needed home care. The data were analyzed in the MAXQDA qualitative data analysis program in accordance with Colaizzi’s seven-stage method. Results: The average age of the children in the study group was 85.63±58.40 months. 56.7% of them were male. 40% of the children were followed up with a diagnosis of neurological disease. All children discharged from the intensive care unit had tracheostomy. 95.4% of them used home-type mechanical ventilators, and 95.3% were fed enterally. In line with the data obtained from the interviews of the parents, it was determined that there were difficulties in terms of feelings about discharge, physical conditions for home care, family relationship, social relationship, difficulty in physical care, inadequacy in support systems and financial status. Conclusion: The home care of children, who are dependent on medical technology and discharged from intensive care, is mostly performed by their families. Children dependent on medical technology should be supported by home care personnel to avoid potential risks. © 2024 by Society of Pediatric Emergency and Intensive Care Medicine
Para Politikasının Evrimi: Klasik Görüşten Yeni Uzlaşı Temelli Makro İhtiyati Para Politikası Araçlarına
No full textPara politikası; parasal büyüklüklerin ayarlanma ve etkilerinin piyasalara yansıma hızı, ekonomik koşullara hızlı adaptasyonu, merkez bankalarının bağımsızlığı, iletişim yoluyla karar birimlerinin beklentilerini şekillendirme gücü gibi nedenlerle tercih edilen ve parasal büyüklüklerin kontrolü yoluyla makroekonomik istikrara katkı sağlayan uygulamalar bütünüdür. Araç olarak kullanılan parasal büyüklüklerin ekonomik değişkenleri hangi yönde, ne ölçüde ve hangi kanallarla etkilediği makroekonominin en önemli tartışma konularından biridir. Kısa ve uzun dönem ayrımı bir tarafa bırakılırsa para politikasının etkilerine yönelik yaklaşımlar, paranın reel değişkenleri etkilediğini savunanlar ile paranın sadece fiyatlar genel düzeyini etkilediğini savunanlar olmak üzere iki ana grupta toplanabilir. Para politikası açısından tek sorun paranın nötr olup olmaması değil, aynı zamanda hangi parasal büyüklüklerin kontrol altında tutulması gerektiği ve söz konusu değişkenlerin diğer ekonomik değişkenlerle nasıl bir etkileşim hâlinde olduğudur. 1980’li yıllardan itibaren uluslararası para rejiminin değişmesi, sermaye hareketlerinin serbestleşmesi, finansal araç çeşitliliğinin ve erişilebilirliğin artmasıyla birlikte para politikasına fiyat istikrarı yanında finansal istikrarı sağlama görevi de yüklendi. Para politikası üzerine tartışmalar günümüzde de güncelliğini korumakta ve finansal sistemdeki gelişmelerle birlikte derinleşmektedir. Çalışmada başlıca makroekonomik görüşlerin para politikasına ilişkin teorik tartışmaları, bu tartışmaların politika uygulamalarına yansımaları ve küresel finansal krizle birlikte para politikasının amaç ve araçlarında meydana gelen değişimler tarihsel ve analitik bir yaklaşımla ele alınmaktadır
A variable-order fractional memristor neural network: Secure image encryption and synchronization via a smooth and robust control approach
No full textIn this research, we introduce and investigate a variable-order fractional memristor neural network, focusing on its engineering applications in synchronization and image encryption. This study stands out as a pioneering effort in proposing such an architecture for image encryption purposes. Distinct from conventional fractional-order systems, our model incorporates a time-varying fractional derivative, leading to more complex behaviors. Through numerical simulations, we vividly demonstrate the chaotic dynamics of the system. Our results further reveal the system's outstanding performance in image encryption applications. To augment the system's efficiency, we introduce a robust control strategy that guarantees smooth stabilization and synchronization of the variable-order fractional system. Considering the unique variable-order fractional nature of the system, we provide theoretical validations and empirical evidence supporting its stability and convergence properties. Additionally, we present synchronization outcomes between pairs of such neural networks employing our robust control approach. Our numerical analyses firmly substantiate the superiority of our control strategy, particularly highlighting its precision, robustness, and ability to maintain chattering-free performance under external disturbances. © 2024 Elsevier Lt
Ankara University İbni Sina Hospital Newborn Hearing Screening Reference Center and Early Intervention Results; [Ankara Üniversitesi İbni Sina Hastanesi Yenidoğan İşitme Taraması Referans Merkez ve Erken Müdahale Sonuçları]
No full textObjective: To determine the relationship between hearing screening results and risk factors, and to present the results of audiological evaluation and intervention in infants who failed newborn hearing screening or who were screened but referred to our reference center due to hearing loss risk factors. Material and Methods: The audiological evaluation and intervention results of 708 newborns referred to our reference center between January 2018 and August 2022 were examined retrospectively. Results: Of the 708 infants who participated in our study, 248 failed and 460 passed newborn hearing screening. The rate of having at least one risk factor was 65.14% in those who passed and 64.59% in those who failed the screening test. The first most common risk factor was the presence of hyperbilirubinemia. However, according to the binary logistic regression analysis performed to determine the effect of variables on newborn hearing screening, sibling hearing loss, chronic disease, consanguineous marriage and craniofacial anomaly variables were found to be the factors influencing the result of the test (p<0.05). Six hundred twenty four infants had normal hearing levels, 16 infants lost follow-up, 27 infants were diagnosed with conductive, 2 with mixed, 37 with bilateral sensorineural and 2 with unilateral sensorineural hearing loss due to neuropathy. Thirty-seven infants with bilateral sensorineural hearing loss were referred to hearing aid use and special education. The mean age at audiologic evaluation was 5.81±2.96 months, the mean age at diagnosis of hearing loss was 6.43±3.25 months, and the mean age at initiation of hearing aid use was 7.45±3.25 months. Conclusion: These results once again demonstrated the importance of newborn hearing screening and the role of risk factors in the early diagnosis and intervention of hearing loss