Processing of T6 heat-treated Al-12Si-0.6Mg alloy

BAYRAKTAR, Senol/0000-0001-8226-0188WOS: 000516671000001In this study, ternary Al-12Si-0.6Mg material was manufactured by gravity die casting method in induction melting furnace. Microstructure images of alloy were taken on optical microscope after T6 heat treatment. Hardness, yield and tensile strength and breaking elongation of as-cast and heat-treated materials were measured by universal methods. CNC lathe was used for cutting tests and dynamometer was used to measure cutting force. Cutting tests were performed by using different cutting speeds-CS (450-500-550 m/min), feed rates-FR (0.05-0.15-0.25 mm/rev) and constant depth of cut-DOC (1.5 mm). Uncoated (A), CVD-TiCN + TiN (B) and PVD-TiAlN+TiN (C) coated carbide inserts were selected as a cutting tool. in the microstructural observations, it was determined that the structure of the material made up of aluminum rich alpha, primary and eutectic silicon, delta (Al4FeSi2) and pi (Al8Mg3FeSi6) phases. the heat treatment refined the phases in the structure of the alloy. in addition, it has been determined that it improves mechanical properties (hardness, yield and tensile strength) by spheroidizing silicon particles. As a result of the cutting tests, it was detected that the cutting force (CF) reduced with T6 heat treatment at all CS and FR values. the CF, BUE (Built up edge) and BUL (Built up layer) heightened with increasing FR, while it reduced with increasing CS on all cutting tools. CF, BUE and BUL were formed at least in tools A, B and C, respectively. While continuous chip formation was detected in the as-cast part, brittle chip formation was observed in the heat-treated part due to the reduction in breaking elongation of the material.Recep Tayyip Erdogan University Scientific Research Projects Coordinatorship [FYL-2017-827]This work was supported by the Recep Tayyip Erdogan University Scientific Research Projects Coordinatorship [No. FYL-2017-827]

Efficacy and safety of endoscopic retrograde cholangiopancreatography in pregnancy: A high-volume study with long-term follow-up

Background/Aims: Pancreaticobiliary diseases are observed more frequently in pregnancy due to increased biliary stone formation. There are some concerns about the use of endoscopic retrograde cholangiopancreatography (ERCP) because of potential fetal exposure to radiation and serious adverse events, such as post-ERCP pancreatitis, which increases fetal or maternal morbidity and mortality. The aim of this study was to evaluate the efficacy and safety of ERCP during pregnancy and to present our experience. Materials and Methods: This study included 25 pregnant patients who underwent ERCP due to biliopancreatic pathologies between 2010 and 2017. Indications for ERCP were choledocholithiasis (n=12), biliary pancreatitis (n=9), and acute cholangitis (n=4). ERCP procedures were performed using fluoroscopy (n=18) and the non-radiation technique (n=7). The duration of fluoroscopy was recorded in all cases. Fetal and maternal complications were both assessed. Results: The mean age of patients was 29.4 (range, 21–40) years, and the mean duration of pregnancy was 19.9 weeks. All the 25 ERCP procedures were performed successfully. Biliary sphincterotomy was performed in all patients, and 18 patients with choledocholithiasis underwent stone extraction. The average procedure duration was 11 min, and the average duration of fluoroscopy was 6 s. There were no major complications in any patient. After the deliveries, the newborns were apparently healthy during the follow-up period of 1–7 years. Conclusion: Either conventional or non-radiation ERCP procedures can be performed successfully in pregnancy, with no increase in the number of feto-maternal complications when performed by experienced endoscopists

Intragastric balloon therapy for obesity: Is it safe and effective?

Aim: Bariatric surgery is a costly and invasive method with permanent effects and medications for treatment of obesity is less costly but may cause systemic side effects. Intragastric balloon (IGB) therapy is a minimal invasive and temporary option between medical therapy and bariatric surgery. The aim of this study is to evaluate the safety and efficiency of intragastric balloon application and present our results. Methods: 39 patients who underwent IGB therapy between 2015 and 2017 were included in the study. IGB was advanced into the stomach, and then the balloon was filled with saline and methylene blue solution. The patients were assessed by a nutritionist during the follow-up period and after balloon removal they were evaluated for results.Results: Of 39 patients, 33 were female and the median body mass index (BMI) was 33.2 kg/m2 before the procedure. Three patients (7.6%) could not tolerate the balloon; therefore balloon extraction was performed on the day 1, 5 and 25. Median duration of therapy was 8 months (1 day-17 months). While excessive weight loss (EWL) ratio was 22.8% in patients whose balloon was removed in 6 months, EWL ratio was 41.6% in patients whose balloon remained more than 6 months. The median BMI after balloon removal was 28.3 kg/m2. The only complication was spontaneous IGB deflation and excretion transanally. Conclusion: Intragastric balloon therapy may be recommended as a safe and effective option for the patients who have had failed attempts of diet and exercise and will not undergo bariatric surgery

Comparative study of machine learning techniques to predict fuel consumption of a marine diesel engine

The motivation of this study is to compare four different machine learning algorithms which are support vector regression, multiple linear regression, J48 pruned tree, and M5 Rules, to predict the fuel consumption (FC) of a large marine diesel engine utilized as the main engine on a tanker vessel. This study aims to fill a literature gap by comparing two algorithms, which have not been used for this problem in the rule and tree-based literature, with the other two frequently used algorithms. The data gathered from noon reports and the logbook of an oceangoing tanker vessel involves the operational and environmental parameters. The model performances, prediction accuracy, and error deviations on the test set are demonstrated. The importance of each feature on fuel consumption is discussed regarding the rules created by the algorithms. The M5 Rules algorithm has the highest performance with the truest predictions with a correlation score of 0.9666, mean absolute error of 2.3536, and root mean squared error of 3.3947. Slip, speed, distance, and wind direction are the operational and environmental dependent variables that have more influence on the FC. M5 Rules algorithm has provided a clear sorting for each feature's importance regarding conditions

HİDROLİK KEYNESYEN YAKLAŞIMIN BİR ELEŞTİRİSİ: DENGESİZLİK KEYNESCİLİĞİ

DergiPark: 401124klujfeasAmaç:Buçalışmada Hidrolik Keynesyen Yaklaşım’ın Keynesyen İktisadi Düşünce’yi Klasikİktisadi Düşünce ile birleştirme çalışmalarına yöneltilen eleştirilerDengesizlik Keynesçiliği Yaklaşımı temelinde ele alınacaktır. Bu bağlamdaçalışmada Hidrolik Keynesyen Yaklaşım’ın piyasa denge analizine karşı çıkarakKeynes’in genel teorisinin bir dengesizlik modeli olduğunu öne süren veöncülüğünü Robert Wayne Clower ve Axel Leijonhufvud’un yaptığı DengesizlikKeynesçiliği Yaklaşımı incelenecektir. Yöntem: Alan yazın tarama vederleme yöntemi kullanılmıştır.Bulgular: Dengesizlik KeynesçiliğiYaklaşımı, Keynes’in teorisinin Walrasyan denge analiziylebirleştirilemeyeceğini savunur. Bu bağlamda öncülüğünü Clower ve LeijonhufvudKeynes Teorisi’ni, Walrasyan olmayan genel denge durumu etrafında; eksik bilgi,yanlış fiyatlar gibi kavramlarla yorumlayarak Keynes’in teorisinin birdengesizlik modeli olduğunu savunur

EXAMINATION OF ACCIDENTS AND CRITICAL LOCATIONS, INVOLVING CITYLINE FERRIES IN THE STRAIT OF ISTANBUL

Istanbul, which is the largest city in Turkey and acting as a bridge between two continents, plays a vital role in internal and external trade. Istanbul is also a cultural and educational centre of the country. The ferry transportation between continents has a great importance in the city transportation. Approximately 20 million people live in this region and suffer from traffic jam. In Istanbul, people use alternative ways to save their time. The best alternative is marine transportation. As a transportation method, marine transportation is naturally risky. Accidents, that have caused many pecuniary losses and intangible damages have occurred during the history of transportation with ferries. This study aims to find out critical points which show dangerous areas according to data of accidents, in ferry transportation in Istanbul. Specialists may criticize these points and suggest solutions to avoid effects of ferry-line accidents in future. Specialists create certain maps to help public corporations so that they can benefit from these resulted maps when they decide to create new lines. Istanbul has lots of ferry lines and many of people use these lines; so accidents are unavoidable. This paper will be a guidebook for new lines and it also helps reduce any of losses related to ferry transportation. a This study deals with issues related to ferry accidents and selection of right line in Istanbul. Creating the right line is always a difficult task for the public corporations. This study is hoped to provide different perspective for corporations so that they can select the most likely effective ways easily

An evaluation of methanol engine utilization regarding economic and upcoming regulatory requirements for a container ship

Examining the effects of converting marine diesel engines to methanol engines in terms of economics, the environment, and forthcoming regulatory requirements is the aim of this study. The article stands out by using an assessment that looks at how the retrofit application affects meeting Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII) criteria as well as an economic and environmental analysis of retrofitting a ship with a methanol engine based on present circumstances and projections for the future. An oceangoing container ship's noon reports for a forty-day cruise have been obtained to perform the analysis. Two different methanol engine retrofit scenarios having smaller (ME1) and larger (ME2) power outputs have been evaluated. Results demonstrated that both ME1 and ME2 engines have considerably reduced operational carbon dioxide (CO2) emissions and their CII values are 9.893 and 9.674 respectively. The ME1 with a 12.259 value has great performance in terms of EEXI which is quite significant since the EEXI of the reference container is 21.272. The usage of renewable (RN) methanol is found highly critical in terms of lifetime (LT) emissions. Despite falling behind in the electricity production cost (EPC) metric, ME1 generally outperformed ME2 in economic comparison, and the payback period (PBP) is calculated at 9.63 years with 2023 prices. The economic model forecast that PBP can be reduced to 4.44 years for the same scenario with the possible developments in methanol production and distribution technologies by 2050

Comparison of two minimal invasive techniques of splenectomy: Standard laparoscopy versus transumbilical multiport single-site laparoscopy with conventional instruments

Background: Laparoendoscopic single-site (LESS) splenectomy which is performed on small number of patients, has been introduced with better cosmetic outcome, less postoperative pain, greater patient satisfaction and faster recovery compared to standard laparoscopy. Materials and Methods : Thirty six patients were included in the study comparing standard laparoscopic splenectomy (LS, 17 patients) transumbilical multiport splenectomy performed with conventional laparoscopic instruments (TUMP-LS, 19 patients). Two groups of patients were compared retrospectively by means of operation time, intra- and postoperative blood loss, perioperative complications, packed red cell and platelet requirements, lenght of hospitalization, pain scores and patient satisfaction. Results: There was no mortality in any of the groups, and no significant differences determined in operative time (P = 0,069), intraoperative blood loss (P = 0,641), patient satisfaction (P = 0,506), pain scores (P = 0,173) and the average length of hospital stay (P = 0,257). Umbilical incisions healed uneventfully and no hernia formation or wound infection was observed during follow-up period (2-34 months). There were no conversions to open surgery. Conclusions: Transumbilical multiport splenectomy performed with the conventional laparoscopic instruments is feasible and could be a logical alternative to classical laparoscopic splenectomy by combining the advantages of single access techniques and standard laparoscopy

A SWOT-AHP analysis on biodiesel as an alternative future marine fuel

Alternative fuels especially those produced in a green way are essential for meeting supplying the world's growing energy needs. Biodiesel is becoming more prominent to meet international maritime organization regulations, minimize reliance on fossil fuels, and lessen the rising harmful emissions in the maritime sector. Four different generations have been investigated in the production stage in which a wide range of fuel types have existed including biodiesel, bioethanol, and renewable diesel. To investigate all facets of biodiesel usage as a marine fuel, the SWOT-AHP method is utilized in this paper in which 16 maritime experts with an average of 10.5 years of experience participated. SWOT factors and sub-factors have been developed in light of the literature review focused on biomass and alternative fuels. The AHP method is utilized for data acquisition from specified factors and sub-factors according to their superiority to each other. The analysis demonstrates the main factors ‘PW and sub-factors’ IPW values, and CR values to calculate the local and global rank of factors. Results highlighted that “Opportunity” has the highest prominence among the main factors; however, “Threats” remain at the lowest level. Moreover, “Tax privilege on green and alternative fuels supported by the authorities” (O4) is the one with the highest weight compared to the other sub-factors. Noteworthy energy consumption will be fulfilled in the maritime industry in addition to the development of new-generation biodiesel and other alternative fuels. This paper will be a quite valuable resource for experts, academics, and industry stakeholders to lessen the ambiguity around biodiesel. Graphical abstract: [Figure not available: see fulltext.]