Metal Kesme Analizleri İçin En Uygun Visko Plastik Modelin Belirlenmesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada, metal kesme simülasyonları için en uygun viskoplastik malzeme modelinin belirlenmesi amaçlanmaktadır. Farklı malzeme modelleri ile gerçekleştirilen sonlu eleman analizleri neticesinde kesme sırasında oluşan tepki kuvvetleri belirlenmiştir. Belirlenen kuvvetler deneysel çalışmalar ile karşılaştırılarak malzeme modelinin yüksek gerinim hızlarındaki doğruluğu tespit edilecektir. Bu sayede metal kesme simülasyonları ile kesici takim üzerindeki stresin doğru modellenmesi ve kesme kuvvetine bağlı olarak gelişen olan takim aşınmalarının gözlemlenebilmesi hedeflenmektedir.Aim of this study  to determine the most suitable viscoplastic material model for metal cutting simulations. As a result of the finite element analysis made with differnent material models, reaction forces  have determined during cutting process. Reliability of material models at high strain rates will determined, by the comparision of these forces with experimantial results. This means,By using metal cutting simulations, stress over cutting tools will be model correctly and the tool wear can be observed which caused by cutting forces

An investigation on deformation behaviors of energy absorbers for passenger coaches

Thin-walled structures is used commonly as energy absorbers at the front and back of the coaches. These parts should be designed to minimize the damage to the vehicle and prevent the passengers from fatality and/or injury by absorbing the collision energy in railway transportation. In this paper, deformation behaviors of tube like structures with truncated cone under the axial impact load were investigated by means of finite element analysis (FEA). The energy absorbers having tube like structures were modelled at the same weight and have three different wall thickness and taper angle. As a result of FEA, the performances of straight and truncated cone type energy absorbers were compared in terms of energy absorption capacities and an optimization study was done to determine the effects of thickness and taper angle on energy absorbing performances of the members. The analysis of variance in 95% confidence level was applied in order to determine the effects of design parameters on total efficiency (TE). Besides, optimum design parameters for TE were determined by using Taguchi optimization methodology. Thickness was found as the most significant parameter on total efficiency with 60.52% percentage contribution ratio according to ANOVA results

The role of the geographıc conditions in the development of the city Bolvadin

Kentlerin kurulması ve gelisiminde, fiziki ve beseri faktörler önemli rol oynar. Fiziki faktörler, ortaya çıkardıkları dogal ortam ile kentin gelisimini saglarken, beseri faktörler de bu sahayı isleyerek ve biçimlendirerek etkide bulunur. Cografya ile kentler arasında, çok yakın fakat karmasık iliskiler vardır. Tüm yerlesim birimleri için geçerli olan bu durum, Bolvadin kenti için de söz konusudur. Bolvadin, alüvyal tabanlı bir ova üzerine kurulmus, Selçuklu Dönemi’nden günümüze kadar, kaza statüsünü sürdürmüs bir kent yerlesmesidir. Kentin kurulus sahası ve çevresinde genel olarak, karasal iklimin özellikleri görülmektedir. Yerlesmenin en önemli su kaynaklarını, Akarçay ve Eber gölü olusturmaktadır. Genel hizmetler bakımından, Afyon kentinden sonra ikinci sırada gelmektedir. Hizmet ve sanayi fonksiyonları ön plana çıkmasına ragmen, tarımın kent üzerindeki etkisi açıktır. lçe merkezinde tahıl tarımı yaygın olarak yapılmakta olup, hayvancılık gelismistir. Kentte bulunan Alkaloit fabrikası, ülkemizin tek, grubunda Dünya’nın en büyük fabrikası konumunda olup, stratejik bakımdan önemlidir. Konya, Eskisehir, stanbul yol güzergâhında yer alması ve yolların kavsak noktasında bulunması Bolvadin’in gelisimine olumlu etki yapmaktadır. Ulasım avantajı nedeniyle, canlı bir ticari hayat vardır. Bizanslılardan bu yana tanınan Heybeli Termal Tesisleri, yapılan son çevresel düzenlemelerle, kente önemli turizm geliri saglamaktadır.The factors of physical and human being have a great role in the constitution and development of the cities. While the physical factors providing the development of the town with the help of natural situation, the factors of human influence with processing and shaping these areas. This situation, which is valid for all settlements, is valid for the town of Bolvadin. The town is settled down on a plain with an alluvial bottom, it has been town since the period of Seljukids. In general, in and vicinity of the settlement of the city, continental climate is seen. The most important water springs of the settlement are Akarçay and Lake Eber. As for the general services, it is in the second grade after the city of Afyon. Service and industrial functions are important but agriculture is more important than the others. Grain agriculture and stock-breeding are very important in particularly. Alkaloid factory which is strategically very important for the town is the largest one in Turkey and in the World. Bolvadin is at the junction of some roads of Konya, Eskisehir and stanbul and this location affects the development of the town positively. There is a very active trade-life in Bolvadin owing to available conditions in transportation. Heybeli spa known since the period of Byzantions supplies a great tourism profit to the town of Bolvadin with the help of recent environmental reorganization

Investigation of strontium master alloy addition effect to Galfan (%95 zn, %5 al) microstructure

Bu çalışmada, stronsiyum elementinin galfan alaşımı (%95 Zn, %5 Al) üzerindeki mikro yapısal etkileri incelenmiştir. Stronsiyum elementi doğada saf olarak çok nadir bulunduğundan, mastar alaşım şeklinde tedarik edilmiştir. Bu alaşım, eriyik galfan alaşım içerisine belirli sıcaklık, ortam ve karıştırma parametreleri dikkate alınarak eklenmiş ve galfan mikro yapısı üzerindeki değişimler incelenmiştir. Deneysel çalışmalar, laboratuvar ortamında gerçekleştirilmiştir. Laboratuvar çalışmasında, galfan külçeleri kül fırınında ergitilerek bahsedilen parametreler ışığında üzerine mastar alaşım eklenerek külçe halinde döküm alınmış, daha sonra dökümü alınan numunelerin mikro yapısal değişimleri incelenmiştir. Mikro yapısal incelemeler için, firma bünyesinde bulunan metalografi laboratuvarında metalografik işlemler yapılmış olup, diğer incelemeler için Çukurova Üniversitesi Merkezi Araştırma Laboratuvarı’ndan hizmet alımı yapılarak SEM analiz tekniği kullanılmıştır.In this study, microstructural impacts of strontium element in galfan alloy (%95 Zn, %5 Al) microstructure were investigated. The strontium element was supplied as master alloy due to the fact that strontium is quite rare element on the earth. Master alloy was added into molten galfan alloy by considering certain conditions such as temperature, atmosphere and mixing etc. After that, changes in galfan microstructure was investigated. The experimental studies were done in laboratory. During study, galfan ingots were melted in furnace next it was mixed in the light of parameters that mentioned above with master alloy and then new alloy was cast as ingot. Afterwards, alteration of casted specimens microstructures were researched. Metallographic operations were carried out in metallography laboratory in plant, and Scanning Electron Microscopy analysis technique was used for other investigations from Cukurova University Central Research Laboratory by outsourcing

Bacterial Translocation Relationship with Enteral L-Glutamine and L-Alanine in Experimental Rat Burn Model

Objective:The aim of this experimental study is to research the effects of L-alanine and L-glutamine, which are being widely used on intensive care patients, on the liver, structural changes in the small intestine, wound healing, and bacterial translocation.Method:Twenty male Sprague Dawley rats which weighe 190-230 gr were used in this study. Rats were separated into two randomized groups. In accordance with experimental rat burn model, skin burn was created in every rat and both groups were fed equally for 21 days. The experimental group was administered L-glutamine + L-alanine containing product (Dipeptiven®, Fresenius Kabi BadHamborg, Germany) for 5 mL/kg/day orally. At the end of the 21st day, all rats were sacrificed. Biopsy materials were obtained from the liver, small intestine, and burn wound, and blood culture was taken under sterile conditions. In pathologic examination, structural changes in tissues and wound healing were evaluated. In microbiologic examination, the effects of L-glutamine and L-alanine on bacterial translocation were evaluated by comparing small intestine and blood cultures.Results:No structural difference was seen among small intestine biopsies between two groups. No liver damage was seen in the experimental group while live biopsies showed grade 1 damage in the control group. Epithelization and granulation were detected as better in the pathologic examination of skin biopsies obtained from burn wound in the experimental group. Microbiologic examination showed bacterial replication in a total of 4 rats from the control group, two rats showed replication of S. aures in the small intestine and blood culture and two rats showed replication of S. epidermidis in the small intestine and blood culture. No replication was determined in any rats from the experimental group.Conclusion:In the light of findings acquired from this study done with experimental rat burn model, we think that the use of L-glutamine + L-alanine will have positive effects on wound healing and help preventing the bacterial translocation in burn patients as a supporting product

A Comprehensive Coronal and Axial Bone Dimension and Cartilage Thickness Evaluation of the Distal Humerus: Age and Sex Differences

Objective: There are limited data on bone dimension and cartilage thickness of the distal humeral articular surface. This study aimed to evaluate sex- and age-related bone dimension and cartilage thickness differences and assess the effect of cartilage thickness on distal humeral shape. Design: Elbow magnetic resonance images of 180 healthy participants were evaluated. Cartilage thicknesses of the trochlea and capitellum were measured at 19 points using coronal and axial images. In addition, bone diameters were measured from the flexion-extension axis to the 19 points on the coronal and axial magnetic resonance images. Sex differences were evaluated, and the correlation between age and measurement parameters was assessed. Results: Significant sex differences regarding the diameters of the axial trochlear bone, coronal lateral trochlear bone, and medial capitellar bone, cartilage thickness at the apex of the lateral trochlear ridge in the axial and coronal plane and at the most lateral point of the capitellar articular surface in the axial plane were observed. A negative correlation was observed between age and axial plane trochlear bone dimensions and between age and coronal plane lateral trochlear and medial capitellar bone dimensions. No significant correlation was found between cartilage thickness and bone dimensions. Conclusions: Bone dimension and cartilage thickness at the distal humerus vary according to sex and age. The data could be used in the donor site selection and graft preparation while osteochondral autograft transfer and allograft transplantation, and in the development of gender-compatible hemiarthroplasty implants. © The Author(s) 2020

A novel marker of systemic inflammation in psoriasis and related comorbidities: Chitotriosidase

Background/aim: Chitotriosidase (ChT) is an enzyme secreted by activated macrophages and neutrophils in response to proinflammatory signals. There is growing evidence indicating that ChT activity reflects the systemic inflammatory status. This study aimed to investigate whether serum ChT activity increased in patients with psoriasis and related comorbidities. Materials and methods: This cross-sectional study included 53 (28 with associated comorbidities and 25 without comorbidities) patients with psoriasis and 52 healthy volunteers. All participants underwent laboratory investigations for serum ChT levels, complete blood count, erythrocyte sedimentation rate, C-reactive protein, and serum lipid levels. Results: The patients with psoriasis showed significantly higher levels of ChT activity as compared to the healthy controls (23.5 ± 11.4 vs. 17.5 ± 10.4 μmol/mL/hour; p = 0.015). Additionally, the ChT activity was significantly higher in patients with comorbidities than in those without (p = 0.042). Conclusion: Our data support the pathogenetic role of inflammatory processes induced by macrophage activation in patients with psoriasis and related comorbidities. We believe that high ChT activity in patients with psoriasis may serve as an early prediction of the possible related comorbidities. © TÜBİTAK

The Effect of Tympanic Membrane Perforation Site, Size and Middle Ear Volume on Hearing Loss

Objective:The aim of this study was to analyze the location and the size of perforation in cases with tympanic membrane perforation, its relation to the manubrium mallei and middle ear volume, and to investigate how these are correlated with the severity and frequencies of conductive hearing loss.Methods: This prospectively designed study included the patients who presented to the the Department of Otorhinolaryngology at the Dokuz Eylül University with hearing loss or tinnitus complaints in the period from June 2014 through June 2017 and were identified to have tympanic membrane perforation in their otoscopic examination. Patients who underwent myringoplasty and type 1 tympanoplasty and whose air-bone gap was found lower than 10 dB in the postoperative audiological examination were included in the study. Effects of the perforation size, the perforation site, and the relationship of the perforation with the manubrium, as well as the effects of the middle ear volume on the severity and frequency of conductive hearing loss were compared.Results: The study included 44 ears of 38 patients (13 male and 25 female) of whom six had tympanic membrane perforation in both ears. Air conduction threshold and air-bone gap were significantly found higher if the perforation area was wide (p<0.05), the perforation involved both the anterior and the posterior quadrants (p<0.05), had contact with the manubrium mallei (p<0.05), and the middle ear volume reduced (p<0.05).Conclusion: Solely tympanic membrane perforation affects hearing function; nevertheless, hearing function are better in cases, which have perforations small in size, no contact with manubrium mallei and well pneumatized middle ears

Reliability of Frozen Section Pathology in Transoral Laser Laryngectomy

Objective:To evaluate the reliability of frozen section analysis in transoral laser laryngectomy (TOLL).Methods:A retrospective analysis was conducted for patients who underwent TOLL in a university hospital between January 2012 and February 2014. The grade of the tumor and the histopathological diagnosis were noted. The results of frozen section pathologies and routine histological examinations were compared.Results:A total number of 84 sections from 21 patients with a mean age of 57.3 years were included in the study. All the patients were operated with superpulse continuous mode carbon dioxide laser with a power of 5–8 watts. Squamous cell carcinoma was histologically diagnosed in all patients. The tumor was grade 1 in 80.95% of the patients, grade 2 in 9.52%, and grade 3 in 9.52%. A routine histopathological examination confirmed the frozen section in 94.04% of the patients.Conclusion:Laser surgery is a commonly preferred treatment modality in early-stage laryngeal carcinomas, in particular. However, a safe surgical margin is a debate in transoral laser surgery. In light of our results, we can conclude that frozen section pathology is a reliable method to achieve safe surgical margins in TOLL