The Relationship of Burr Height and Blanking Force with Clearance in the Blanking Process of AA5754 Aluminium Alloy

The effect of clearance and sheet thickness in the AA5754 sheet material blanking process on the burr formation and blanking force was examined experimentally. Measurements of the burr height and blanking force were performed in a modular die with six different clearance values (8 %, 10 %, 12 %, 14 %, 16 % and 18 %) by applying the blanking process to the AA5754 sheet metal of 1 mm and 2 mm in thickness. The influence rate of parameters affecting the burr height, the blanking force, and the mathematical relationship between them were identified by using the analysis of variance (ANOVA) and the regression analysis. Thus, it was determined that the burr formation increased with increased clearance and that the blanking force was not affected in the same proportion. In addition, it was found that the sheet thickness and clearance affected the burr formation at rates of 23.24 % and 76.15 %, respectively; on the other hand, the sheet thickness and clearance affected the blanking force at rates of 99.72 % and 0.24 %, respectively

Statistical Evaluation of the Influence of Temperature and Surface Roughness on Aluminium Sheet Metal Forming

The influences of temperature and surface roughness on the forming of the AA3003-H111 aluminium alloy sheet material have been investigated by using the finite element method. For this purpose, material cards have been firstly created based on the sheet material behaviour at different deformation temperatures. As a result of the forming analyses performed at different temperature values and surface roughness values, it has been determined that the increase in the surface roughness reduces the amount of thinning while it increases the amount of forming force and the springback. It has also been determined that there is a slight increase in the amount of thinning, while the temperature rise reduces the amount of forming force and the springback. In addition, the influence levels of temperature and surface roughness have been determined by statistical analyses

Evaluation of Diffusion Tensor Imaging Findings in Clinically Isolated Syndrome and Relapsing-Remitting Multiple Sclerosis Patients

Objective: To compare diffusion tensor imaging (DTI) findings of the normal-appearing white matter (NAWM) and corpus callosum (CC) in patients with clinically isolated syndrome (CIS) and relapsing-remitting multiple sclerosis (RRMS) and a healthy control (HC) group. Materials and Methods: The CIS (n = 10), RRMS (n = 29), and HC (n = 13) groups were evaluated by DTI in this retrospective study. Mean diffusion (MD) and fractional anisotropy (FA) maps as well as MD and FA measurements were made from the corpus callosum genu (CCG), corpus callosum splenium (CCS), and NAWM areas from the frontal, parietal, occipital and temporal lobes. Results: The mean FA values of the NAWM in the temporal lobes were bilaterally lower in both the CIS and RRMS groups than in the HC group. However, no difference was found between the CIS and RRMS groups. In addition, the CIS group had lower FA values in the CCG, whereas the RRMS group had lower FA values in the CCS compared with the HC group. The MD values were significantly different in the CCG between the RRMS and HC groups. Conclusion: DTI contributes to detecting early changes in the NAWM and CC in patients diagnosed with CIS and RRMS. Additionally, DTI can aid in the follow-up care and management of these patients

Mechanıcal Modellıng Of Temperature And Deformatıon Speed Dependent Formabılıty Behavıour And Mıcrostructure Of Dp1000 Dual Phase Steel Sheet

Bu tez çalışması kapsamında otomotiv endüstrisindeki kullanımı büyük önem kazanmış olan geliştirilmiş yüksek mukavemetli DP1000 çeliğinin deformasyon davranışı detaylı olarak incelenmiştir. Tez çalışmasının ilk bölümünde, 25 °C, 100 °C, 200 °C, 300 °C sıcaklıklarında ve 0,0083 s-1, 0,16 s-1 deformasyon oranlarında tek eksenli çekme deneyleri gerçekleştirilerek malzemenin mekanik özellikleri belirlenmiştir. Çekme testlerinden elde edilen veriler kullanarak Hill-48 ve Barlat-89 akma kriterine göre akma yüzeyleri oluşturulmuş, sıcaklık ve hıza bağlı akma davranışı incelenmiştir. Marciniak-Kuczynski modeli ile şekillendirme sınır eğrileri elde edilerek malzemenin şekillendirilme kabiliyeti tespit edilmiştir. Tez çalışmasının ikinci bölümünde ise çeliğin mikroyapısındaki değişimleri gözlemlemek amacıyla iki ve üç boyutlu olarak mikroyapısı modellenmiş ve sonlu elemanlar yöntemi kullanılarak deformasyon analizleri gerçekleştirilmiştir. Şekillendirme işleminin düşük sıcaklıklarda ve yavaş deformasyon hızlarında yapılmasının uygun olacağı sonucuna ulaşılmıştır.In this thesis, the deformation behaviors of DP1000 steel, an improved high strength steel type, which has gained great importance in the automotive industry, have been examined in detail. In the first part of the thesis study, the mechanical properties of the material were determined by performing uniaxial tensile tests at temperatures of 25 °C, 100 °C, 200 °C, 300 °C and 0,0083 s-1, 0,16 s-1. By using the data obtained from the tensile tests, yield loci were formed according to the Hill-48 and Barlat-89 yield criterion and the flow behavior was investigated due to temperature and deformation speed. Formability behaviour of the material was determined by obtaining forming limit curves by using MarciniakKuczynski model. In the second part of the thesis study, two and three dimensional microstructure modeling were used to observe the changes in the microstructure of the material and deformation analyzes were performed using the finite element method. It has been achieved that it is appropriate to perform the forming process at low temperatures and slow deformation rates

Experimental and theoritical investigation of the effects of press speed and material on formability of sheet metal parts

Yapılan çalışmada DP600 ve DP780 sac malzemenin şekillendirilmesinde deformasyon hızı ve malzemenin şekillendirme işlemine etkileri incelenmiştir. Öncelikle, DP600 ve DP780 sac malzemeye, farklı deformasyon hızlarında 0˚, 45˚, 90˚ hadde yönlerinde çekme testleri yapılarak malzeme davranışını belirlenmesi sağlanmıştır. Ayrıca, matematiksel bir model oluşturularak, Autoform sac malzeme şekillendirme simülasyon programı yardımıyla farklı deformasyon hızlarında sac malzemenin şekillendirilebilirlik analizleri yapılmıştır. Analizler sonucunda, farklı deformasyon hızlarının DP600 ve DP780 sac malzemelerin şekillendirmesine etkileri incelenerek, kullanılan sac malzemeler için en uygun şekillendirme hızı değerleri tespit edilmiştir.In this study, the effects of deformation speed and material to formability of DP600 and DP780 sheets were be investigated. At first, to be determine the behavior of material, tensile tests were performed to DP600 and DP780 sheets in different deformation speed and 0 ˚, 45 ˚, 90 ˚ rolling directions. Furthermore, by creating a mathematical model, sheet material formability analyzes were carried out on different deformation speeds with the help of Autoform. As results of analysis, by the effects of deformation speed on sheet metal formability of DP600 and DP780 materials investigating and for sheet materials used the most suitable deformation speed was determined

Covert Channel Detection Using Machine Learning

A covert channel is a communication method that misuses legitimate resources to bypass intrusion detection systems. They can be used to do illegal work like leaking classified (or sensitive) data or sending commands to malware bots. Network timing channels are a type of these channels that use inter-arrival times between network packets to encode the data to be sent. In this study, we worked with two types of network covert channels: Fixed Interval and Jitterbug. We were able to distinguish these channels from legitimate ones by using decision trees that use four statistical features (mean, variance, skewness, and kurtosis)

Automated question generation and question answering from Turkish texts

All rights reserved.While exam-style questions are a fundamental educational tool serving a variety of purposes, manual construction of questions is a complex process that requires training, experience and resources. Automatic question generation (QG) techniques can be utilized to satisfy the need for a continuous supply of new questions by streamlining their generation. However, compared to automatic question answering (QA), QG is a more challenging task. In this work, we fine-tune a multilingual T5 (mT5) transformer in a multitask setting for QA, QG and answer extraction tasks using Turkish QA datasets. To the best of our knowledge, this is the first academic work that performs automated text-to-text question generation from Turkish texts. Experimental evaluations show that the proposed multitask setting achieves state-of-the-art Turkish question answering and question generation performance on TQuADv1, TQuADv2 datasets and XQuAD Turkish split. The source code and the pretrained models are available at https://github.com/obss/turkish-question-generation