Optimization of machining parameters in face milling using multi-objective Taguchi technique

In this research, the effect of machining parameters on the various surface roughness characteristics (arithmetic average roughness (Ra), root mean square average roughness (Rq) and average maximum height of the profile (Rz)) in the milling of AISI 4140 steel were experimentally investigated. Depth of cut, feed rate, cutting speed and the number of insert were considered as control factors; Ra, Rz and Rq were considered as response factors. Experiments were designed considering Taguchi L9 orthogonal array. Multi signal-to-noise ratio was calculated for the response variables simultaneously. Analysis of variance was conducted to detect the significance of control factors on responses. Moreover, the percent contributions of the control factors on the surface roughness were obtained to be the number of insert (71.89 %), feed (19.74 %), cutting speed (5.08%) and depth of cut (3.29 %). Minimum surface roughness values for Ra, Rz and Rq were obtained at 325 m/min cutting speed, 0.08 mm/rev feed rate, 1 number of insert and 1 mm depth of cut by using multi-objective Taguchi technique

Modeling and optimization of face milling process parameters for AISI 4140 steel

In this study, the effect of cutting parameters such as the depth of cut, feed rate, cutting speed and the number of inserts on surface roughness were investigated in the milling of the AISI 4140 steel. The optimal control factors for surface quality were detected by using the Taguchi technique. Experimental trials were designed according to the Taguchi L18 (2¹x3³) orthogonal array. The statistical effects of control factors on surface roughness have been established by using the analysis of variance (ANOVA). Optimal cutting parameters were obtained by using the S/N ratio values. The ANOVA results showed that the effective factors were the number of inserts and the feed rate on surface roughness. However, the depth of cut and the cutting speed showed an insignificant effect. Additionally, the First-order and Second-order regression analysis were conducted to estimate the performance characteristics of the experiment. The acquired regression equation results matched with the surface roughness measurement results. The optimal performance characteristics were obtained as a 0.5 mm depth of cut, 0.08 mm/rev feed rate, 325 m/min cutting speed and 1 number of inserts by using the Taguchi method. Additionally, the confirmation test results indicated that the Taguchi method was very prosperous in the optimization of the machining parameters to obtain the minimum surface roughness in the milling of the AISI 4140 steel

15-yıllık periyotta İstanbul Türkiye’de dermatofitoz şüpheli köpek ve kedilerden izole edilen dermatofitler: Güncellenmiş rapor

The present research was aimed to determine the prevalence of dermatophytes isolated from symptomatic dogs and cats, within a 15-year-period, in the city of Istanbul, Turkey. Dermatological specimens were collected from 1504 dogs and 846 cats, which were presented clinical signs of ringworm. Direct microscopy and mycological cultures were performed. The fungal growth rate was detected at 8.2% and 22.8% from dogs and cats, respectively. Microsporum canis was the most frequently isolated species followed by Trichophyton spp., M. gypseum, T. mentagrophytes, M. nanum, other Microsporum spp. moreover T. tonsurans. The cats less than two-year age and more than ten-year age showed a statistically significant higher isolation rate of infection (p < 0.05). There were no statistically significant differences between the age of the dogs and the dermatophyte isolation rate and between the gender of the dogs and cats and the dermatophyte isolation rate. As a conclusion, the data suggest an updated report on local epidemiology and define potential etiologic agentsBu araştırma, İstanbul ilinde 15 yıllık bir süre içinde semptomatik köpek ve kedilerden izole edilen dermatofitlerin yaygınlığını belirlemeyi amaçlamıştır. Dermatolojik örnekler ringworm klinik belirtileri gösteren 1504 köpek ve 846 kediden toplandı. Direkt mikroskopi ve mikolojik kültürler yapıldı. Mantar üreme oranları, köpeklerde % 8.2 kedilerde % 22.8 olarak saptandı. En sık izole edilen tür Microsporum canis idi. Bunu Trichophyton spp., M. gypseum, T. mentagrophytes, M. nanum, diğer Microsporum spp. ve T. tonsurans takip etti. İki yaşından küçük ve on yaşından büyük kediler, istatistiksel olarak anlamlı derecede yüksek bir etken izolasyon oranı gösterdi (p <0.05). Köpeklerin yaşı ve dermatofit izolasyon oranları ile kedi ve köpeklerin cinsiyeti ve dermatofit izolasyon oranları arasında istatistiksel olarak anlamlı bir fark bulunmadı. Sonuç olarak, veriler yerel epidemiyoloji üzerine güncel bir rapor sunmakta ve olası etiyolojik ajanları tanımlamaktadır

Efficacy of subsequent treatments in patients with hormone-positive advanced breast cancer who had disease progression under CDK 4/6 inhibitor therapy

Background: There is no standard treatment recommended at category 1 level in international guidelines for subsequent therapy after cyclin-dependent kinase 4/6 inhibitor (CDK4/6) based therapy. We aimed to evaluate which subsequent treatment oncologists prefer in patients with disease progression under CDKi. In addition, we aimed to show the effectiveness of systemic treatments after CDKi and whether there is a survival difference between hormonal treatments (monotherapy vs. mTOR-based). Methods: A total of 609 patients from 53 centers were included in the study. Progression-free-survivals (PFS) of subsequent treatments (chemotherapy (CT, n:434) or endocrine therapy (ET, n:175)) after CDKi were calculated. Patients were evaluated in three groups as those who received CDKi in first-line (group A, n:202), second-line (group B, n: 153) and ≥ 3rd-line (group C, n: 254). PFS was compared according to the use of ET and CT. In addition, ET was compared as monotherapy versus everolimus-based combination therapy. Results: The median duration of CDKi in the ET arms of Group A, B, and C was 17.0, 11.0, and 8.5 months in respectively; it was 9.0, 7.0, and 5.0 months in the CT arm. Median PFS after CDKi was 9.5 (5.0–14.0) months in the ET arm of group A, and 5.3 (3.9–6.8) months in the CT arm (p = 0.073). It was 6.7 (5.8–7.7) months in the ET arm of group B, and 5.7 (4.6–6.7) months in the CT arm (p = 0.311). It was 5.3 (2.5–8.0) months in the ET arm of group C and 4.0 (3.5–4.6) months in the CT arm (p = 0.434). Patients who received ET after CDKi were compared as those who received everolimus-based combination therapy versus those who received monotherapy ET: the median PFS in group A, B, and C was 11.0 vs. 5.9 (p = 0.047), 6.7 vs. 5.0 (p = 0.164), 6.7 vs. 3.9 (p = 0.763) months. Conclusion: Physicians preferred CT rather than ET in patients with early progression under CDKi. It has been shown that subsequent ET after CDKi can be as effective as CT. It was also observed that better PFS could be achieved with the subsequent everolimus-based treatments after first-line CDKi compared to monotherapy ET.Breast Cancer Consortiu

İmalat sektöründe kalite güvencesi ve proses kontrol sistemlerinin belirlenmesi

TEZ1519Tez (Doktora) -- Çukurova Üniversitesi, Adana, 1994.Kaynakça (s. 282-286) var.xii, 286 s. ; 30 cm.

Process capability analysis a machining company

Üretim proseslerinde ürünlerin spesifikasyon limitleri içerisinde üretilmesi istenmektedir. Bu hedef proses yeterliliği ile basarılabilir. Proses yeterliliğini belirlemede Cp ve Cpk indeksleri kullanılmaktadır. Bu çalısmada, silindir gömleği üreten orta ölçekli bir isletmenin talaslı üretim hattında proses yeterlilik analizi yapılmıs ve yeterlilik indeksleri (Cp ve Cpk) hesaplanmıstır. Yapılan analiz sonucunda isletmenin proses yeterliliğinin “yeterli olmadığı” görülmüstür. ?sletmenin proses yeterliliğini sağlayabilmesi için proses değiskenliğini azaltıcı önlemler alması gerekmektedir.In manufacturing process, the products are wanted to be produced within specification limits. This goal can be achieved by process capability. Cp and Cpk indices are used for determining the process capability. In this study, process capability analysis have been done in machining line of a medium sized company which produces cylinder liner, and process capability indices (Cp and Cpk ) have been calculated. As a result of analysis, it has been seen that the process is not adequate. In order to satisfy the process capability, company must take actions to reduce the process variability

Comparison of the assembly line balancing algorithms

Montaj hattı dengeleme algoritmalarının karşılaştırılması konusu araştırılırken, geçmişte yapılan bazı çalışmalara ve günümüzde kullanılan yöntemlere deyinilerek, duş kabinleri üreten bir fabrikada bu konu ile ilgili araştırmalar yapılmıştır. Buradaki amaç optimum seviyede seri üretimi sağlamak için etkin bir yerleşim planı ile dengelenmiş bir montaj hattının kurulmasıdır. Bunlar için en önemli faktörler, iş elemanları arasındaki öncelik ilişkileri ve çevrim süresidir.Yapılan araştırmalarda montaj hattındaki iş elemanlarının tarif ve tanımları Metot Etüdü teknikleri kullanılarak yapılmıştır. Aynı zamanda İş Ölçümü teknikleri kullanılarak montaj hattındaki her bir iş elemanının gerekli standart zamanları ölçülmüştür. Fabrikada, üretilen çeşitli modeller için montaj hattının ön şemaları çizilip, çeşitli çevrim sürelerindeki denge kayıpları bulunarak hattın verimliliği ölçülmüştür,Gelecekte en önemli faktörün zaman ve insan olabileceğinden dolayı geliştirilen stratejilerin bu doğrultuda olması gerekmektedir. Ayrıca yapılan çalışmaların teoriden ziyade fiili olarak uygulanabilirliği düşünülerek yapılması, uygulanılabilirlik açısından önem arz etmektedir,We realized that some works which we done in past and methods which we used nowadays, while the subject of comparison of the assembly line balancing algorithms were searching. The researches are made about this subject in factory which produces shower cabins. To settle a balanced assembly line with an active settlement plan for supplying the series production in optimum level is the aim of this subject for these the precedence relations and cycle lime between the work element are the most important factors.The description and definition of work element on the assembly line are made by using the method study technics. Each work element in assembly line is measured by using the work-measure technics. The front schemes ofassmbly line has been drawn for each model which were produced in factory. The productivity of assembly line has been measured by finding the losses of balance in each cycle time. In the future time and person could be come the most important factors. Because of this research improving strategies should be in this direction. The works about this subject should be done in real practice

A research related to the applications of process control techniques for correlated processes

Çoğu istatistiksel proses kontrol teknikleri gözlemlerin birbirinden bağımsız ve normal dağıldığı varsayımına dayanır. Bununla beraber, istatistiksel proses kontrolünün uygulamalarında bu kabul, verilerin birbirlerine bağımlı olmasından dolayı gerçeklerden bir hayli uzaktır.Bu çalışma, kontrol dışı sinyallerin oto korelasyondan olup olmadığını tespit etmek için, istatistiksel proses kontrol teknikleri korelasyonla olduğunu ispatladığımız verilere uygulanmıştır Verilerin oto korelasyonla olduğu ispatlandıktan sonra oto korelasyonu yok etmek için uygun bir zaman serisi modeli, ARIMA (2,1,0), tespit edilmiştir. Tespit edilen model MINITAB-13 istatistik programı kullanılarak, orijinal verilerdeki oto korelasyon filtre edilmiştir. Shewart, CUSUM, ve EWMA kontrol şemaları rezidülere ve orijinal verilere uygulanmıştır.Most of the statistical process control (SPC) techniques are developed for the assumption that considers the measured data to be normaly and independently distributed. In real world applications of SPC, however, this assumption is very far from the truth due to the dependence of data on itself. In this study, the Statistical Process Control (SPC) techniques were applied to the auto correlated data. After proving that the data was auto correlated, a suitable time series model, ARIMA(2,1,0), for the particular set of data was adapted to remove the correlation from the observations. The predicted time series model was applied to filler out the auto correlation from the original data by using the MINITAB-13 statistical software tool

The practical research on the subject of the statistical quality control and statistical process control

Bir süreçteki süreç parametresinde yer değiştirmenin yakalanmasında kontrol şemalarından yararlanılmaktadır. Örnek büyüklüğü, bu yer değiştirmelerin yakalanmasında kontrol şemaları üzerinde farklı etkilere sahiptir. Süreç ortalamasındaki orta ve büyük yer değiştirmelerin belirlenmesinde X kontrol şemasının etkili olduğu bilinmektedir. Örnek büyüklüğünün arttırılması ile X kontrol şemaları küçük yer değiştirmeleri yakalamada etkili hale gelmektedirler. Çalışmada, gerçek veriler kullanılarak X kontrol şemasının örnek büyüklüğünün arttırılması ile süreçteki küçük değişimleri yakalama yetenekleri ortaya konulmuştur. Ayrıca, aynı veriler için CUSUM şemaları da oluşturularak, X kontrol şemasının bu etkisi test edilmiştir.Control Charts are most commonly used to detect process shifts in a process parameter. Sample size has different effects on control charts which detects pocess shifts. It is known that if the X control chart is being used primarly to detect moderate-to-large process shifts, then relatively small sample size are effective. On the other hand, X control charts which have large sample size, are more effective to detect small shifts.In this study, the ability of X control charts on detecting small shifts in a process-was presented by increasing sample size by using original data. In addition, CUSUM charts were prapared to test the performance of X control charts. Then, results were presented. Control, charts were plotted by Statistica and MINITAB-13 statistical software