Murat Korkmaz

• Hacettepe University

In this study, these machine learning methods (MLMs) were used for the first time in the literature to compare the temperature performance of two counterflow Ranque–Hilsch vortex tubes (RHVT) connected in parallel. As input parameters, two different pressurized fluids, three distinct materials, and six types of nozzles were selected, while the temp...

Vorteks tüp (VT) basit bir borudan oluşmaktadır. Vorteks tüp aynı anda hem ısıtma hem de soğutma işlemini basınçlı akışkan kullanarak yapabilen ve çevre dostu olarak bilinen bir cihazdır. Bu çalışmada deney cihazını kurmak için iki tane ters akışlı vorteks tüp birbirine paralel bağlanmıştır. Deney cihazında alüminyum ve pirinç malzemelerden yapılan...

Vorteks tüpleri kullandıkları basınçlı akışkanlardan dolayı çevre dostu olarak bilinmektedir. Aynı zamanda basınçlı akışkan kullanarak ısıtma ve soğutma işlemini aynı anda yapabilmektedir. Vorteks tüpün kontrol vanası dışında hareketli parçasının bulunmaması bakım kolaylığı sağlamaktadır. Bu çalışmada iki tane karşıt akışlı vorteks tüpü (VT) birbir...

Today, when heating or cooling processes are carried out, environmentally harmful refrigerants are used. The Counterflow Ranque-Hilsch Vortex Tube (CFRHVT) consists of a simple tube. In RHVT, the heating and cooling process is done with the help of a pressurized fluid, causing little harm to the environment. In this study, 2, 3, 4, 5 and 6 orifice...

The vortex tube, which consists of a simple tube, is a device that can simultaneously heat and cool thanks to environmentally friendly pressurized fluids (air, oxygen, nitrogen, etc.). Many studies have been included in the literature to evaluate the Ranque-Hilsch Vortex tube's performance and to reveal influential factors. Variance analysis, linea...

This study planned to model a counter-flow Ranque-Hilsch Vortex Tube (RHVT) using compressed air and oxygen gas by machine learning to separate the thermal temperature. From within machine learning models, Linear Regression (LR), Support Vector Machines (SVM), Gaussian Process Regression (GPR), Regression Trees (RT), and Ensemble of Trees (ET) were...

Bu çalışmada, basınçlı oksijen gazı kullanarak aynı anda hem soğutma hem de ısıtma yapabilen ve kontrol vanası dışında hareketli parçası bulunmayan basit borudan meydana gelen Karşıt Akışlı Ranque-Hilsch Vorteks Tüp (KARHVT) kullanılmıştır. KARHVT’nün tasarımında boru 7 mm iç çapında ve 100 mm gövde uzunluğunda imal edilmiştir. KARHVT’ünde, nozul o...

In the counterflow Ranque-Hilsch vortex tube (RHVT), the output control valve on the hot fluid side is left entirely open. The data were obtained using polyamide and brass materials and nozzles at 50 kPa intervals from 150 kPa to 700 kPa inlet pressure. In counterflow RHVT, the difference (ΔT) between the temperature of the cold outflow and the tem...

The need for energy continues to increase rapidly all over the world day by day. The demand for energy is rising in developing economies and industrial production areas in these economies. Energy is one of the essential inputs for business areas. Today, most energy is used in buildings for the purpose of heating, cooling, and air conditioning. The...

16 17 This paper used an Artificial neural network-based ternary diagram to predict temperature separation in a counter 18 flow Ranque Hilsch Vortex Tube. Working fluid and nozzle materials were selected as effect parameters, and the 19 temperature difference between hot and cold outlets was a performance indicator. In multiple regression and neura...

Ranque-Hilsch Vortex Tube (RHVT) is a system that consists of a simple pipe with no moving parts except for the control valve, working with pressurized fluid and performing both heating and cooling processes at the same time. In the study, air with an inlet pressure of 150 to 700 kPa at 50 kPa intervals was used in RHVT with an internal diameter of...

Ranque-Hilsch Vortex Tube (RHVT) is a system that consists of a simple pipe with no moving parts other than the control valve, which can create the heating and cooling process using pressurized fluid. Although air is generally used as the pressurized fluid in these systems, oxygen was used as the pressurized fluid in this study. In the experimental...

Ranque-Hilsch Vortex Tube (RHVT) is a system that consists of a simple pipe, has no moving parts except the control valve, works with pressurized fluid, and making both cooling and heating processes at the same time. Air is generally used as the pressurized fluid in RHVT, and oxygen gas was used as fluid in the experimental study. In this study, a...

It is known that energy needs are increasing all over the world due to the rapid increase in the human population and industrialization. This situation has caused many countries to turn to alternative and renewable energy sources. Today, the most widely used energy source is fossil fuels (oil, natural gas, coal). Considering that fossil fuels are r...

Dünyada 1970‘den sonra yaşanan teknolojik gelişmeler ile birlikte teknoloji kullanımı yaygınlaşmıştır. Yaşanan teknolojik gelişmeler, nüfus artışı, eğitimli işgücü ihtiyacındaki artış, eğitim kalitesinin yükseltilmesi, mevcut eğitim sistemlerinin mali kısıtlamalar ve eğitim maliyetinin düşürülmesi, yaşam boyu öğrenme gibi nedenler tüm ülkelerde eği...

Abstract Nuclear hazards can be defined as fragmentation of the atom or the unfolding of energy generated by the combination of two atoms and influencing the environment. Nuclear hazards can arise asaccidents that may occur in facilities where radioactive materials are kept. In these facilities, thereare natural disasters such as earthquakes, floo...

Nükleer tehlikeler, atomun parçalanması ya da iki atomun birleşmesi ile açığa çıkan enerjinin kontrolsüz olarak yayılması ve çevreyi etkilemesi olarak tanımlanabilir. Radyoaktif materyallerin tutulduğu tesislerde oluşabilecek kazalar sonucunda radyasyon salınımı ortaya çıkabilmektedir. Bu tesislerde meydana gelen kazaların sebepleri arasında öngörü...

Özet: Eğitim öğretimde son yıllarda yaşanan teknolojik gelişmelerden biri de uzaktan eğitim yönteminin üniversitelerde uygulamaya konulmasıdır. Bu yöntem bazı üniversitelerde eğitim öğretim programındaki tüm dersleri kapsayabildiği gibi bazı üniversitelerde ise seçilen birkaç ders için uygulanmaktadır. Hacettepe Üniversitesi'nde Türk Dili derslerin...

ÖZET Radyoaktivitenin keşfedilmesinden bu yana radyasyon ve radyoaktif maddeler yaşamımızın birçok farklı alanında kullanılmaya başlamıştır. Günümüzde radyoaktif kaynaklar başta enerji üretimi olmak üzere endüstri, tıp, güvenlik ve araştırma gibi birçok alanda yaygın olarak kullanılmaktadır. Ancak radyoaktivite, canlıların özellikle insanların hay...

ÖZET Ülkemizde okutulan ortak zorunlu derslerde (Türk Dili, İngilizce, Atatürk İlkeleri ve İnkılâp Tarihi) öğrencilerin bu derslere ilgileri, derslere devamları ve elde ettikleri başarı oranları uzun süredir tartışılan bir konudur. Ortak zorunlu dersler özellikle tarih bilincinin oluşmasında, lisanın etkin olarak kullanılmasında ve yabancı dilin öğ...

Bu çalışmada, Hacettepe Üniversitesi Polatlı Teknik Bilimler Meslek Yüksekokulunda bulunan, İnşaat Teknolojisi Programı, Harita ve Kadastro Programı, Bilgisayar Programcılığı Programı ve Gaz ve Tesisatı Teknolojisi Programı öğrencilerinin ortak zorunlu derslerdeki (Türk Dili, İngilizce, Atatürk İlkeleri ve İnkılâp Tarihi) başarı durumlarının karşıl...

We present a rare case of progressive familial intrahepatic cholestasis within a family. A 34-yearold female became a living-related liver transplant donor for her son, who had the disease. Nine years after the transplant, the mother developed severe intrahepatic cholestasis, for which she was evaluated after using an oral contraceptive drug. She p...

Objectives: We investigated the effect of hepatitis B virus in kidney transplant patients in terms of patient care and survival. Materials and methods: We retrospectively analyzed kidney transplant patients from 1993 to 2013. A control group with negative serology was selected. The hepatitis B virus-positive group was divided into 2 subgroups ba...

Objectives: We aimed to investigate the colonoscopy findings in patients after kidney transplant. Materials and methods: We retrospectively analyzed kidney transplant patients who had colonoscopy examinations for various indications between 2011 and 2015. Results: Eighty-one patients (25 women and 56 men) with a mean age of 39 years (range, 18...

Objectives: Spontaneous bacterial peritonitis, unless originating from surgery or an intra-abdominal source, is an infection diagnosed by neutrophil counts greater than 250/mm³ in ascites. Spontaneous bacterial peritonitis is the most common infection among patients hospitalized with cirrhosis, with a prevalence of 9% and a risk of development amo...

Vasoconstrictor therapy with terlipressin and concomitant albumin can improve renal function in patients with hepatorenal syndrome (HRS) type 1, but the efficacy of therapy in patients with active infection is controversial. The aim of this study was to investigate the efficacy, adverse effects, and predictors of terlipressin therapy and to find ou...

Background: Head trauma is associated with a significant risk of cerebrospinal fluid (CSF) fistula. Methods: In this study, it was aimed to report twenty-two cases subjected to operative intervention for otorrhea, rhinorrhea and oculorrhea with associated traumatic lesions. Majority of the cases had moderate to severe head trauma with a Glascow...

Aim: In this study we examined the patients with traumatic acute subdural hematoma (ASDH) in an attempt to determine the factors affecting the GCS, amount of blood loss and mortality. Material and methods: This study was retrospectively performed on 99 patients who were operated for traumatic ASDH.Age, sex, mechanism of trauma, the time in hours...

Hepatitis B and D virus coinfection or superinfection lead to chronic liver disease and have poor treatment results and poor prognosis. After transplant, these patients have difficult problems. We aimed to report long-term data of liver transplant recipients who had hepatitis B and D virus-related chronic liver disease. This retrospective, longitud...

There is no correlation between alanine aminotransferase levels, viral load, and histologic findings at dialysis in patients with chronic hepatitis C virus infection. Identification of the severity of hepatitis C-related liver disease before transplant could provide valuable data about the risk for liverrelated mortality after transplant. In this s...

Studies have demonstrated worse graft and patient survival among hepatitis C virus-positive patients following kidney transplant. Eradication of hepatitis C virus infection before renal transplant with interferon should be considered in hepatitis C virus-infected patients undergoing dialysis who are on the waiting list for transplant. We investigat...

Chronic hepatitis C virus infection compromises hemodialysis patients and increases liver-related mortality. Interferon treatment is associated with improved sustained virological response rates and increased risk of graft loss after kidney transplant. This may be related to the development of antihuman leukocyte antigen antibodies, which may be a...

Objective: In this study, we aimed to evaluate the epidemiological, demographic and clinical characteristics of tularemia patients observed in Eskisehir province of Turkey. Methods: Probable Tularemia Case Report Forms submitted to Eskisehir Public Health Agency Department of Infectious Diseases between January 2011 and July 2013 were evaluated ret...

Aim: Ethanol causes oxidative degradation of the mitochondrial genome in the brain. This effect could contribute to the development of brain injury in some alcoholic patients. We investigated the protective effect of caffeic acid phenyl esther (CAPE) and intralipid (IL) on oxidative stress and neurotoxicity induced by ethanol intake. Material and...

Background/aims: The efficacy of immune response against hepatitis C virus (HCV) is determined by human leukocyte antigen (HLA) molecules of the host which present HCV antigens to CD4 + and CD8 + T lymphocytes. In this study, we aimed to investigate the possible relationship between the frequencies of certain HLA class I-II alleles and the natural...

Chronic hepatitis C virus infection is the most common cause of chronic liver disease and indication for liver transplant in Western countries. Viral infection may recur after transplant in most patients. The diagnosis of histologic recurrence of hepatitis C virus infection after liver transplant may be difficult and may be confused with acute cell...

Aim: Surgical approaches to the pituitary have undergone numerous refinements over the last 100 years. The fully endoscopic transsphenoidal approach has gained widespread use all around the world. We report the results of a consecutive series of patients who underwent pituitary surgery using a pure endoscopic endonasal approach and the results of...

Aim: Spongostan™ is a sterile, water-insoluble, porcine gelatin absorbable sponge, which is widely used as a hemostatic material. The aim of this study is to test the anti-fibrotic capacity of Spongostan™, using a craniotomy model in an experimental rabbit model. Material and Methods: Eighteen rabbits were divided into two groups: Each group consis...

Background/aims: The precise mechanism of functional dyspepsia is yet to be elucidated. Helicobacter pylori infection and psychiatric disorders are implicated in the etiology. We aimed to determine the prevalence of psychiatric co-morbid disorders in patients with Helicobacter pylori-positive functional dyspepsia and the impact of existing psychia...

Background: Cerebrospinal fluid (CSF) leaks are a potential complication resulting from a dural violation during spinal surgery. Persistent CSF leakage leads to either pseudomeningocele formation or a CSF fistula, which can result in poor wound healing, infection, and meningitis. Diagnosis of a CSF leak during surgery necessitates direct surgical r...

Chylous ascites is the accumulation of lipid-rich lymph in the peritoneal cavity. The usual cause in adults is lymphatic obstruction or leakage caused by malignancy. Non-malignant causes include postoperative trauma, cirrhosis, tuberculosis, pancreatitis and filariasis. A variety of treatment options have been proposed for the management of chylous...

Carbohydrate antigen 19-9 is most valuable as a serum marker for pancreatic and biliary cancer, but increased concentrations occur in several other gastrointestinal malignancies. A carbohydrate antigen 19-9 value of >1,000 U/ml usually indicates a digestive cancer and has been reported to have a specificity greater than 99% for pancreatic cancer; n...

Drugs are related to the etiology of acute pancreatitis in approximately 1.4-2.0% of cases. Although antibiotics constitute a small number of the drugs suspected, tetracycline is the most encountered antibiotic among those drugs. A 33-year-old woman was admitted to the emergency room complaining of nausea and abdominal pain after the use of doxycyc...

In this study, the effect of the nozzle number and the inlet pressures, which vary from 150 to 700 kPa with 50 kPa increments, on the heating and cooling performance of the counter flow type vortex tube has been modeled with an artificial neural network (ANN) and multi-linear regression (MLR) models by using the experimentally obtained data. In the...

During the course of acute viral hepatitis, some functional and structural changes to the gallbladder can occur. Acute acalculous cholecystitis is an extremely rare complication of acute viral hepatitis. Acalculous cholecystitis associated with acute viral hepatitis can present as different conditions. Some of these are self-limiting and heal spont...

Bezoars are the most common foreign bodies of the gastrointestinal tract. Clinical manifestations vary depending on the location of the bezoar, from no symptoms to acute abdominal syndrome. The ingestion of cling film, which is used for preserving food, may lead to a mechanical obstruction of the gut, especially at the second portion of the duodena...

The correlation of the risk of malignancy with the sum of the diameters of small colonic polyps is unknown, and data regarding this topic are lacking. In this study, the relationship between the sum of the diameters of the total number of colonic polyps and poor histopathologic characteristics was examined. A total of 920 neoplastic colon polyps we...

In this study, we investigated possible independent predictive factors for survival, other than MELD score, in patients with cirrhosis. We reviewed the serum sodium, cholesterol, albumin, and platelet levels of 99 patients with cirrhosis and investigated the possible correlation of these parameters with survival period. We found that 77% and 81% of...

The aim of this study was to determine the risk of polyps <6 and between 6 and 10 mm in terms of progression to malignancy and to evaluate the influence of age, gender, and colonic localization on malignancy development. Thirteen hundred sixty-nine polyps <10 mm identified in 680 patients were retrospectively evaluated. Sixty-seven and two-tenths p...

The goal of this study was to assess whether mucosal sensitivity is related to different combinations of symptoms and lesions in laryngopharyngeal reflux (LPR) and erosive esophagitis and to determine whether reflux pattern is important in the development of the symptoms and lesions of gastroesophageal reflux disease (GERD) or LPR. We conducted a p...

The aim of this study was to identify the effects of objective laryngopharyngeal reflux (LPR) on the acoustic parameters of patients by comparing their voice samples with that of control subjects. Prospective study in two tertiary reference hospitals. 48 consecutive patients with symptoms related to LPR and 64 control subjects were included in the...

Infection is a serious complication of nutritional support, causing a high rate of mortality and morbidity. Critically ill patients having nutritional support are prone to infectious complications. Questions regarding the effects of the route of nutrition in infectious complications have been asked. We aimed to determine the relationship between th...

The objective of this study was to investigate the effects of types of dialysis treatments on hepatitis C virus infection and the epidemiologic properties of hepatitis C virus (HCV) infection at three Baskent University hospitals, in Ankara, Adana, and Izmir, Turkey, in 655, 326, and 118 patients with end-stage renal disease, respectively. One hund...

To evaluate susceptibility of Helicobacter pylori to amoxicillin and clarithromycin in end-stage renal disease (ESRD) patients and non-uremic controls. The subjects with dyspeptic complaints were 33 ESRD patients and 46 age- and sex-matched non-uremic controls who exhibited H pylori on antral biopsy specimens. The two groups were age and sex matche...

Duodenal varices that develop in patients with portal hypertension rarely cause hemorrhage, but varix rupture is a serious and often fatal event. We report the case of a 38-year-old man with hepatic vein occlusion who was referred to our hospital for gastrointestinal hemorrhage of unknown origin. Upper gastrointestinal endoscopy revealed varices in...