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Prediction of cutting temperatures in turning process by machine learning
No full textFen Bilimleri Enstitüsü, Makine Mühendisliği Ana Bilim Dalı, Makine Mühendisliği Bilim Dalıİşlenmesi zor malzemelerden parça üretilmesinde karşılaşılan olumsuzluklar, talaşlı imalat gibi geleneksel işleme yöntemlerinde yeni arayışlara gidilmesine sebep olmuştur. İşlenmesi zor malzemeleri işleyebilmek ve üretimde verimliliği artırmak için yeni teknolojilerle üretilmiş ileri kesici takımlarla çalışılması, minimum miktarda yağlama ve kriyojenik soğutma gibi yeni tekniklerin kullanıldığı soğutma-yağlama sistemlerinin ve ön ısıtmalı işleme gibi yöntemlerin kullanımı her geçen gün daha fazla tercih sebebi olmaktadır. Özellikle otonom sistemlerin, karanlık fabrikaların yer aldığı dijital imalat uygulamalarının giderek yaygınlaştığı görülmektedir. Önümüzdeki dönemlerde bu otomatik sistemlere entegre olarak çalışacak uygun işleme sıcaklığını tespit edecek, gerekirse ısıtma gerekirse soğutma-yağlama yapacak sistemler için veri alt yapısına ihtiyaç duyulacaktır. Bu çalışmada, malzemelerin talaşlı imalat yöntemleriyle işlenmesini kolaylaştırmak için kesme kuvvetini minimum yapan kesme bölgesindeki sıcaklıklar makine öğrenmesi ile tahmin edilmiştir. Makine öğrenmesi için gerekli veri seti 16MnCr5 çeliği kullanılarak yapılan kuru tornalama deneyleri esnasında, en düşük kesme kuvveti değerlerinin ölçüldüğü deney parametreleri ile sıcaklık değerlerinden oluşmaktadır. Çalışmanın sonucunda, veri seti baz alınarak istenilen değerlerde kesme hızı, ilerleme hızı, kesme derinliği, malzeme ve kesici takım parametreleri modele girilerek, kesme bölgesindeki sıcaklık tahmin edilmiştir. Tahmin edilen sıcaklık ile işleme öncesinde uygun ortam koşulları sağlanarak deneye başlanacağı için takım ve iş parçası aşınmasının, kesme kuvvetinin, yüzey pürüzlülüğünün, kesme sıvısı tüketiminin azaltılması sağlanarak enerjiden, maliyetten ve zamandan tasarruf edilmiş olacaktır.The negativities encountered in the production of parts from difficult-to-machine materials have led to new researches in traditional machining methods such as machining. In order to process difficult-to-machine materials and increase efficiency in production, working with advanced cutting tools produced with new technologies, the use of cooling-lubrication systems using new techniques such as minimum amount of lubrication and cryogenic cooling, and methods such as preheated processing are increasingly preferred. In particular, it is seen that digital manufacturing applications involving autonomous systems and dark factories are becoming more and more common. In the coming periods, a data infrastructure will be needed for systems that will work in integration with these automatic systems, determine the appropriate processing temperature, heat if necessary, cooling-lubrication if necessary. In this study, the temperatures in the cutting zone, which minimizes the cutting force, were estimated by machine learning in order to facilitate the machining of materials with machining methods. The data set required for machine learning consists of the experiment parameters and temperature values in which the lowest shear force values are measured during dry turning experiments using 16MnCr5 steel. As a result of the study, the temperature in the cutting zone was estimated by entering the cutting speed, feed rate, cutting depth, material and cutting tool parameters into the model at the desired values based on the data set. Since the experiment will be started by providing suitable ambient conditions before machining with the estimated temperature, energy, cost and time will be saved by reducing tool and workpiece wear, cutting force, surface roughness, and coolant consumption
Evaluation of putamen area and cerebral peduncle with surrounding cistern in patients with Parkinson's disease: is there a difference from controls in cranial MRI?
No full textObjectives Nigrostriatal dopaminergic neuron loss is essential in pathogenesis of Parkinson's disease (PD). The purpose of this study was to evaluate nigrostriatal structures including the putamen, cerebral peduncle, widths of interpeduncular cistern, and ambient cistern around the midbrain with conventional cranial magnetic resonance images (MRI) in patients with PD.Methods The MRI of 56 subjects was included, which was selected from the radiological data system for this retrospective study. The 29 patients with idiopathic PD were included and their disease duration, Hoehn&Yahr stage, and Levodopa equivalent dose (LED) were recorded. The 27 controls had a normal neurologic examination and cranial MRI. All subjects in the patient and control groups had right-hand dominance. Putamen and cerebral peduncle areas and widths of interpeduncular and ambient cisterns were measured in T2 sequences of MRI. Further statistical analysis was applied to exclude gender and age effect on areas.Results The areas of putamen and cerebral peduncles were significantly reduced in patients with PD compared to the control bilaterally (p < 0.001). Enlargement of interpeduncular and ambient cisterns in patients was higher than in controls, and it was significant (p < 0.001). A correlation was not observed between measurement results and clinical characteristics of patients with PD. Only the cerebral peduncle area/ambient cistern width ratio was significantly correlated with disease duration positively (right r = 0.46 p = 0.012, left r = 0.389 p = 0.037).Conclusion Clinicians should be careful with conventional MRIs of patients with idiopathic PD in practice. It may be different from controls without any neurological disorder, particularly putamen, cerebral peduncles, interpeduncular, and ambient cisterns
Assessing the Early Post-Operative Analgesic Effects of Intra-Operative Lidocaine-Bupivacaine Use at the Incision Line and/or Around the Ovary in Ovariohysterectomy Operations of Dogs on Pain Mediators
No full textThe present study investigated the effectiveness of intra-operative bupivacaine-lidocaine (BLK) combination administration concurrently with meloxicam, a non-steroidal anti-inflammatory drug (NSAID), on the Glasgow Composite Pain Scale Short Form (GCPS-SF) scores and pain mediators in the early post-operative ovariohysterectomy (OHE) period in 30 female dogs of different breeds and ages divided into three equal groups. OHE is reportedly associated with moderate pain. BLK was administered inside the ovarian bursa 10 min before ovary removal in Groups (G) 1 and G2 and linear to the incision line 10 min before entering the abdomen in G1. G3 was the control group. The intergroup comparison of pain mediators and GCPS-SF scores showed no significant difference between the GCPSSF scores at postop0, postop2, postop4, postop8 and postop24 h and the cortisol, TNF-alpha, IL1-beta and NO levels determined at the same timepoints. TNF-alpha at postop24 h showed a significant positive correlation with the postop0 h GCPS-SF score. NO at postop8 h showed a significant negative correlation with the postop4 h GCPS-SF score. However, since these results were not simultaneous, they were disregarded. Although there was no statistically significant difference in post-operative pain and stress among the three groups, surgical stress was higher in G3, as indicated by high postoperative cortisol levels, which suggested the other two protocols involving BLK to be remarkable. Hence, using G1 and G2 protocols appeared feasible considering the post-operative cortisol stress hormone values. Nevertheless, further studies with larger samples are warranted to confirm these inferences
Sociological investigation of the migration phenomena in Keskin through Pierre Bourdieu's concepts
No full textSosyal Bilimler Enstitüsü, Göç ve Ortadoğu Çalışmaları Ana Bilim DalıGöç, Dünya tarihini etkileyen, güncelliğini koruyan ve insanlık tarihi boyunca sürekli yaşanmış bir olgu olarak her zaman karşımıza çıkmaktadır. İnsanlar yaşadıkları yerden bir başka yere kalıcı ya da geçici olarak yer değiştirdiklerinde hem gittikleri yerleri hem de geldikleri yerleri etkilerler. Bu nedenle göçün sosyal, siyasal, ekonomik ve kültürel sonuçları sebebiyle, göç sürecinin yaşandığı yerlerde toplumsal değişimler meydana gelir. Toplumsal yapıda meydana gelen bu değişmeyi incelemek ve içinde yaşadığımız sosyal yapıyı anlamak adına göç olgusu önemli bilgiler yansıtmaktadır. Nitel araştırma yönteminin esas alındığı bu çalışma, Kırıkkale'ye bağlı olan Keskin ilçesindeki göç sürecini incelemeyi, göç süreci sonucu toplumsal yapıda meydana gelen değişimi ve yerli halkın göç sürecinden nasıl etkilendiğini konu edinmektedir. Çalışmanın amacı, Pierre Bourdieu kavramları ve kuramları üzerinden analiz yapılarak, Kırıkkale iline bağlı Keskin ilçesindeki göç olgusunun neden olduğu toplumsal değişimi incelemektir. Göç süreci sonucu toplumsal yapıda meydana gelen bu değişmeyi incelemek adına bu araştırmada elde edilecek veriler önem arz etmektedir. Anahtar Kelimeler: Göç Olgusu, habitus, alan, sermaye, Pierre BourdieuMigration has always appeared as a phenomenon that affects world history, maintains its current status and has been experienced continuously throughout human history. When people move from one place to another, either permanently or temporarily, they affect both the places they go and the places they come from. Therefore, due to the social, political, economic and cultural consequences of migration, social changes occur in places where the migration process takes place. The phenomenon of migration reflects essential information in order to examine this change in the social structure and understand the social structure we live in. This study, based on the qualitative research method, focuses on examining the migration process in the Keskin district of Kırıkkale, the change in social structure as a result of the migration process, and how the local people are affected. In this context, our study aims to examine the social change caused by the phenomenon of migration in the Keskin district of Kırıkkale province, by analyzing Pierre Bourdieu's concepts and theories. The data obtained in this research are important to examine this change in the social structure due to the migration process. Keywords: Migration phenomenon, habitus, field, capital, Pierre Bourdie
Experimental and numerical investigation of hysteretic earthquake behavior of masonry infilled RC frames with opening strengthened by adding rebar-reinforced stucco
No full textAdding a reinforced stucco layer to the masonry infill walls is a preferred method for strengthening RC frame system structures with an easy-to-apply method that does not require a long time, is economical, and does not require detailed and extensive workmanship. However, no research has been discovered as a result of the extensive literature review that investigates the effects of masonry-infilled RC frames strengthened with a reinforced stucco layer on the seismic performance of openings that must be due to architectural requirements such as doors, windows, installations, and similar ventilation systems. As a result, an experimental study was planned to investigate the effects of the dimensions and location of the opening in the masonry infill walls on the performance of the strengthening method with the reinforced stucco layer. The applied strengthening method increased the ultimate load capacity, initial stiffness, and energy dissipation capacity values of reinforced concrete frames with masonry infill walls by 83%, 226%, and 62%, respectively, but resulted in a 38% decrease in displacement-ductility ratios. The study found that the openings in the masonry infill walls harm the performance of the strengthening technique by adding a rebar-reinforced stucco layer and decreasing the success level. When the opening size increased, and the opening was located at the corner of the masonry wall, the performance of the applied strengthening technique was negatively affected and decreased. Furthermore, nonlinear numerical analyses of the experiments conducted as part of the study were performed using ABAQUS finite element software. The numerical analysis results were compared to the experimental results. It has been determined whether numerical analysis models are compatible with experimental results.Gazi UniversityNo Statement Availabl
Push and Pull Factors of Why Medical Students Want to Leave Türkiye: A Countrywide Multicenter Study
No full textPhenomenon: Physician immigration from other countries is increasing as developed countries continue to be desirable destinations for physicians; however, the determinants of Turkish physicians’ migration decisions are still unclear. Despite its wide coverage in the media and among physicians in Türkiye, and being the subject of much debate, there is insufficient data to justify this attention. With this study, we aimed to investigate the tendency of senior medical students in Türkiye to pursue their professional careers abroad and its related factors. Approach: This cross-sectional study involved 9881 senior medical students from 39 different medical schools in Türkiye in 2022. Besides participants’ migration decision, we evaluated the push and pull factors related to working, social environment and lifestyle in Türkiye and abroad, medical school education inadequacy, and personal insufficiencies, as well as the socioeconomic variables that may affect the decision to migrate abroad. The analyses were carried out with a participation rate of at least 50%. Findings: Of the medical students, 70.7% had emigration intentions. Approximately 60% of those want to stay abroad permanently, and 61.5% of them took initiatives such as learning a foreign language abroad (54.5%) and taking relevant exams (18.9%). Those who wanted to work in the field of Research & Development were 1.37 (95% CI: 1.22–1.54) times more likely to emigrate. The push factor that was related to emigration intention was the “working conditions in the country” (OR: 1.89, 95% CI: 1.56–2.28) whereas the “social environment/lifestyle abroad” was the mere pull factor for the tendency of emigration (OR: 1.73, 95% CI: 1.45–2.06). In addition, the quality problem in medical schools also had a significant impact on students’ decisions (OR: 2.20, 95% CI: 1.83–2.65). Insights: Although the percentage of those who want to emigrate “definitely” was at the same level as in the other developing countries, the tendency to migrate “permanently” was higher in Türkiye. Improving working conditions in the country and increasing the quality of medical faculties seem vital in preventing the migration of physicians. © 2023 Taylor & Francis Group, LLC
Estimation of the stress-strength parameter under two-sample balanced progressive censoring scheme
No full textIn this paper, we obtain the stress-strength reliability estimation under balanced joint Type-II progressive censoring scheme for independent samples from two different populations. We simultaneously place two independent samples where the experimental units follow Weibull distributions with common shape parameter beta and different scale parameters alpha, lambda, respectively. The maximum likelihood estimators of the unknown parameters are derived. Further, the Bayesian inference is considered using Lindley's approximation and Gibbs sampling method. Extensive simulations are performed to see the effectiveness of the proposed estimation methods. Further, we derive the optimal censoring scheme in the Bayesian framework by using the variable neighbourhood search method proposed by [Bhattacharya et al. On optimum life-testing plans under type-ii progressive censoring scheme using variable neighbourhood search algorithm. Test. 2016;25(2):309-330]. Further, some simulation schemes are provided to compare the performances of the estimations under the jointly censored samples versus two separate censored samples
On translation hpyersurfaces
No full textFen Bilimleri Enstitüsü, Matematik Ana Bilim DalıBu tez dört bölümden oluşmuştur. Birinci bölümde öteleme hiperyüzeyleri hakkında daha önce yapılan çalışmalardan bahsedilmiştir. İkinci bölüm temel kavramlara ayrılmıştır. Üçüncü bölümde, Rn+1 Öklid uzayında skalar eğriliği sıfır olan öteleme hiperyüzeylerinin denklemleri verilmiştir.Dördüncü bölümde; Rn+1q yarı Öklid uzayında skalar eğriliği sıfır olan öteleme hiperyüzeylerinin denklemleri bulunmuş ve sabit skalar eğrilikli her öteleme hiperyüzeyinin skalar eğriliğinin sıfır olduğu gösterilmiştir.The thesis consists of four chapters. In the first chapter, previous studies on translation hypersurfaces are mentioned. In the second chapter divided into preliminaries. In the third chapter, the equations of translation hypersurfaces with zero scalar curvature in the Euclidean space Rn+1 were given. In the fourth chapter, in the semi-Euclidean space Rn+1q the equations of translation hypersurfaces with zero scalar curvature were found, and it was shown that the scalar curvature of every translation hypersurface with constant scalar curvature is zero
PRESIDENTIAL GOVERNMENT SYSTEM REFLECTIONS ON CENTRAL MANAGEMENT
No full text16 Nisan 2017 tarihinde Türkiye’de yapılan referandum sonrasında hükümet sisteminde değişme yaşan-mış ve 24 Haziran 2018 Cumhurbaşkanlığı seçimleriyle de yeni hükümet sistemi modeli olan Cumhurbaşkanlığı hükümet sistemine geçilmiştir. Cumhurbaşkanlığı hükümet sistemi modeli özellikle, parlamenter hükümet sisteminin yarattığı aksaklıkların giderilmesi, siyasal kriz aşımı ve yönetimde istikrar sağlanması açılarından düşünülmüştür. Yeni sistemle birlikte yürütme organı, bu organın işleyişi ve içerisindeki idari teşkilat yapısında büyük de-ğişikler meydana gelmiştir. Yürütme organı ve yürütme organı içerisinde yer alan idari teşkilat üzerinde yeni sistemle birlikte etkin bir değişimin meydana geldiğini söylememiz mümkündür. Özellikle 2017 yılında yapılan Anayasa değişikliği kapsamında yeni modelin çerçevesi, anayasal görünümü ve Cumhurbaşkanının görev ve yetkileri kapsamında merkezi yönetimde ortaya çıkan son durum ve meydana gelen son değişiklikler ile oluşan yansımalar çalışmamızın ana temasını oluşturmaktadır.After the referendum held in Turkey on April 16, 2017, there was a change in the government system, and with the Presidential elections of June 24, 2018, the new government system model, the Presidential government system, was introduced. The Presidential government system model was especially considered in terms of eliminating the problems caused by the parliamentary government system, overcoming the political crisis and ensuring stability in the administration. With the new system, major changes have occurred in the executive body, the functioning of this body and the administrative organization structure within it. It is possible to say that there has been an effective change in the executive body and the administrative organization within the executive body with the new system. Especially within the scope of the Constitutional amendment made in 2017, the framework of the new model, its constitutional view and the latest situation in the central government within the scope of the duties and powers of the President and the reflections caused by the latest changes constitute the main theme of our study
Genetic analysis of PALB2 gene WD40 domain in canine mammary tumour patients
No full textBackground: DNA repair mechanisms are essential for tumorigenesis and disruption of HR mechanism is an important predisposing factor of human breast cancers (BC). PALB2 is an important part of the HR. There are similarities between canine mammary tumours (CMT) and BCs. As its human counterpart, PALB2 mutations could be a predisposing factor of CMT. Objectives: In this study, we aimed to investigate the impacts of PALB2 variants on tumorigenesis and canine mammary tumor (CMT) malignancy. Methods: We performed Sanger sequencing to detect germline mutations in the WD40 domain of the canine PALB2 gene in CMT patients. We conducted in silico analysis to investigate the variants, and compared the germline PALB2 mutations in humans that cause breast cancer (BC) with the variants detected in dogs with CMT. Results: We identified an intronic (c.3096+8C>G) variant, two exonic (p.A1050V and p.R1354R) variants, and a 3 ' UTR variant (c.4071T>C). Of these, p.R1354R and c.4071T>C novel variants were identified for the first time in this study. We found that the p.A1050V mutation had a significant effect. However, we could not determine sufficient similarity due to the differences in nucleotide/amino acid sequences between two species. Nonetheless, possible variants of human sequences in the exact location as their dog counterparts are associated with several cancer types, implying that the variants could be crucial for tumorigenesis in dogs. Our results did not show any effect of the variants on tumor malignancy. Conclusions: The current project is the first study investigating the relationship between the PALB2 gene WD40 domain and CMTs. Our findings will contribute to a better understanding of the pathogenic mechanism of the PALB2 gene in CMTs. In humans, variant positions in canines have been linked to cancer-related phenotypes such as familial BC, endometrial tumor, and hereditary cancer predisposition syndrome. The results of bioinformatics analyses should be investigated through functional tests or case-control studies.Trkiye Bilimsel ve Teknolojik Arascedil;timath;rma Kurumu [19L0239005]; Ankara University; Scientific and Technological Research Council of Turkey; Scholarship Program in the Priority Fields in Science and Technology fundsThis study was supported by a Ph.D. dissertation project grant from Ankara University, The Scientific Research Projects Coordinator (Project number: 19L0239005). The Scientific and Technological Research Council of Turkey supported the corresponding author in her dissertation phase by 2211-C National Ph.D. Scholarship Program in the Priority Fields in Science and Technology funds