Ab-initio Study of the Structural, Electronic, Elastic and Vibrational Properties of the Intermetallic Pd3V and Pt3V Alloys in the L12 Phase

N. Arlkan,A.Iyigör,A. Candan,M. Özduran,A. Karakoç,S . U ur4,G. Ugur4,A. Bouhemadou,S. Bin-Omran,N. Guechi 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4

Pseudopotential plane-wave method based on density functional theory within the generalized gradientapproximation for the exchange-correlation potential has been applied to study the structural, electronic, elasticand vibrational properties of the binary intermetallic Pd3V and Pt3V in the L12 phase. The optimized latticeconstant, bulk modulus and its pressure derivative, independent single-crystal elastic constants and elasticwave velocities in three different directions are evaluated and compared with the available experimental andtheoretical data. The polycrystalline elastic parameters, hardness coefficient, elastic anisotropy, Debye temperatureare estimated. The electronic band structure, electronic total and partial densities of states, and totalmagnetic moment of the Pd3V and Pt3V alloys are computed and analyzed in comparison with the existingtheoretical and experimental findings. Phonon-dispersion curves and their corresponding total and projecteddensities of states were obtained for the first time using a linear-response in the framework of the densityfunctional perturbation theory.

Design optimization of a fixed wing aircraft

Yayli, Ugur C.,Kimet, Cihan,Duru, Anday,Cetir, Ozgur,Torun, Ugur,Aydogan, Ahmet C.,Padmanaban, Sanjeevikumar,Ertas, Ahmet H. Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.1

Small aircrafts, Unmanned Aerial Vehicles (UAVs), are used especially for military purposes. Because landing fields are limited in rural and hilly places, take-off or landing distances are very important. In order to achieve a short landing or take-off distance many parameters have to be considered, for instance the design of aircrafts. Hence this paper represents a better design to enlarge the use of fixed wing aircrafts. The document is based on a live and simulated experiments. The various components of designed aircraft are enhanced to create short take-off distance, greater lift and airflow without the need for proper runway area. Therefore, created aerodynamics of the remotely piloted aircraft made it possible to use fixed wing aircrafts in rural areas.

A note on -Fubini polynomials

UGUR DURAN,SERKAN ARACI,MEHMET ACIKGOZ 장전수학회 2019 Advanced Studies in Contemporary Mathematics Vol.29 No.2

Motivated by the construction of the generating functions of q-Bernoulli polynomials and q-Euler polynomials satisfying with their important results, we de…ne a new q-class of the Fubini polynomials. We give some new properties including correlations with the number S2;q (n; k) given in the paper. We also de…ne two types q-Fubini polynomials with three parameters and then provide several correlations and identities.

Drilling performance of functionally graded composite: Comparison with glass and carbon/epoxy composites

Ugur Köklü,Okan Demir,Ahmet Avcı,Ayhan Etyemez 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10

Functionally graded composite (FGC) materials are categorized as advanced materials that display different thermal and mechanical responses compared with well-known composites, such as carbon fiber or glass fiber-reinforced composites. This paper presents the experimental results for the drilling of three materials, namely glass/epoxy, carbon/epoxy, and FGC material. FGC was compared with carbon and glass/epoxy composites in terms of thrust force, delamination factor, diameter of hole, and roundness during drilling. This study illustrated that the drilling performance of FGC is considerably more complicated than that of more common composite materials, such as glass/epoxy and carbon/epoxy. Delamination factor at the exit of hole during drilling of FGC was mainly affected by the material placed at the exit of the hole. The proposed cutting parameters and drill geometries to minimize the occurrence of delamination during drilling of carbon/epoxy and glass/epoxy apparently does not meet the expectation in drilling FGC.

A Rare Complication of Lumbar Spinal Surgery: Pneumocephalus

Uğur Özdemir 대한신경손상학회 2017 Korean Journal of Neurotrauma Vol.14 No.2

A 25-year-old male patient with severe thigh and right side pain was presented. In the lumbar magnetic resonance images,there was a contrasting spinal cord tumor image with 1 cm in diameter at the level of the L3 vertebra. The patient was operated and the tumor was totally removed. All the pain of the patient recovered. The patient’s postoperative two days werevery comfortable and the patient was early mobilized. On the third postoperative day, the patient complained of severeheadache, nausea and vomiting. Immediate cranial computed tomography (CT) images was performed. Cerebral pneumocephalus was present in CT. The patient was treated with defnite bed rest and plenty of fluid replacement. After threedays, the patient’s complaints were completely improved. This improvement was confrmed by performing a cerebral CTscan. In the formation of pneumocephalus, air is compressed into the intradural space during operation and this passes tothe cerebral space. Defnite bed rest, abundant fluid replacement and, in addition, highly inspired oxygen therapy are suffcient to correct the condition.

On spacelike rotational surfaces with pointwise 1-type Gauss map

Ugur Dursun 대한수학회 2015 대한수학회보 Vol.52 No.1

In this paper, we study a class of spacelike rotational surfaces in the Minkowski 4-space $\mathbb E^4_1$ with meridian curves lying in 2-dimensional spacelike planes and having pointwise 1-type Gauss map. We obtain all such surfaces with pointwise 1-type Gauss map of the first kind. Then we prove that the spacelike rotational surface with flat normal bundle and pointwise 1-type Gauss map of the second kind is an open part of a spacelike 2-plane in $\mathbb E^4_1$.

The Effects of Process Parameters for Joining of AISI 1010-Cu Alloys by Friction Welded

Ugur Caligulu,Mustafa Acik,Zulkuf Balalan,Nida Kati 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4

In this study, the effects of process parameters for joining of AISI 1010 low carbon steel and copper alloys by friction welded were investigated. Low carbon steel and commercial copper each of 12 mm diameter was used to fabricate the joints. The friction welding tests were carried out using a direct-drive type friction welding machine which was designed and manufactured for this purpose by us. After friction welding, in order to determine the microstructural changes that occurred, the interface regions of the welded specimens were examined by means of OM, SEM, EDS and X-Ray analysis. Microhardness and tensile tests were conducted to determine the mechanical properties of the welded specimens. The experimental results indicated that AISI 1010 low carbon steel could be joined to copper using the friction welding technique and for achieving a welding with a sufficient strength, the friction time has to be held as short as possible, while the rotational speed, friction and forging pressure has to be as high as possible. Tensile strength values also confirmed this result and at the interface did not occurred intermetallic phases. The maximum tensile strength of 294,67 MPa could be obtained for the joints welded under the welding conditions of rotation speed of 2300 rpm, friction pressure of 40 MPa, forging pressure of 80 MPa, friction time of 6 s and forging time of 3 s.

A Rare Complication of Lumbar Spinal Surgery: Pneumocephalus

Uğur Özdemir 대한신경손상학회 2017 Korean Journal of Neurotrauma Vol.13 No.2

A 25-year-old male patient with severe thigh and right side pain was presented. In the lumbar magnetic resonance images,there was a contrasting spinal cord tumor image with 1 cm in diameter at the level of the L3 vertebra. The patient was operated and the tumor was totally removed. All the pain of the patient recovered. The patient’s postoperative two days werevery comfortable and the patient was early mobilized. On the third postoperative day, the patient complained of severeheadache, nausea and vomiting. Immediate cranial computed tomography (CT) images was performed. Cerebral pneumocephalus was present in CT. The patient was treated with defnite bed rest and plenty of fluid replacement. After threedays, the patient’s complaints were completely improved. This improvement was confrmed by performing a cerebral CTscan. In the formation of pneumocephalus, air is compressed into the intradural space during operation and this passes tothe cerebral space. Defnite bed rest, abundant fluid replacement and, in addition, highly inspired oxygen therapy are suffcient to correct the condition.

Physical and Mechanical Properties of Al–Si–Ni Eutectic Alloy

Ugur Böyük 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.6

Al–11.1wt%Si–4.2wt%Ni alloy was directionally solidified upward under different conditions, with different growth rates (V=4.60–243.33 μm/s) at a constant temperature gradient (G=5.82 K/mm) and with different temperature gradients (G=2.11–5.82 K/mm) at a constant growth rate (V=11.63 μm/s) by using a Bridgman type directional solidification furnace. The microstructure of directionally solidified Al–11.1wt%Si–4.2wt%Ni alloy was observed to be irregular plates of Al3Ni and Si within an α–Al matrix from quenched samples. The microhardness, tensile strength and electrical resistivity of the alloy were measured from directionally solidified samples. The dependency of the microhardness, tensile strength and electrical resistivity for directionally solidified Al–Si–Ni eutectic alloy on the solidification parameters were investigated and the relationships between them were experimentally obtained by using regression analysis. Additionally, the variation of electrical resistivity with temperature in the range of 300-825 K for the Al–Si–Ni eutectic cast alloy was also measured using a standard d.c. four-point probe technique. The enthalpy of fusion and specific heat for the same alloy were determined by a differential scanning calorimeter from the heating curve during the transformation from eutectic solid to eutectic liquid. The results obtained in the present work were compared with previous similar experimental results.

The comparison of single incision laparoscopic cholecystectomy and three port laparoscopic cholecystectomy

Ugur Deveci,Umut Barbaros,Mahmut Sertan Kapakli,Manuk Norayk Manukyan,Selcuk ?im?ek,Abut Kebudi,Selcuk Mercan 대한외과학회 2013 Annals of Surgical Treatment and Research(ASRT) Vol.85 No.6

Purpose: Laparoscopic techniques have allowed surgeons to perform complicated intra-abdominal surgery with minimal trauma. Single incision laparoscopic surgery (SILS) was developed with the aim of reducing the invasiveness of conventional laparoscopy. In this study we aimed to compare results of SILS cholecystectomy and three port conventional laparoscopic (TPCL) cholecystectomy prospectively. Methods: In this prospective study, 100 patients who underwent laparoscopic cholecystectomy for gallbladder disease were randomly allocated to SILS cholecystectomy (group 1) or TPCL cholecystectomy (group 2). Demographics, pathologic diagnosis, operating time, blood loss, length of hospital stay, complications, pain score, conversion rate, and satisfaction of cosmetic outcome were recorded. Results: Forty-four SILS cholesystectomies (88%) and 42 TPCL cholecystectomies (84%) were completed successfully. Conversion to open surgery was required for 4 cases in group 1 and 6 cases in group 2. Operating time was significantly longer in group 1 compared with group 2 (73 minutes vs. 48 minutes; P < 0.05). Higher pain scores were observed in group 1 versus group 2 in postoperative day 1 (P < 0.05). There was higher cosmetic satisfaction in group 1 (P < 0.05). Conclusion: SILS cholecystectomy performed by experienced surgeons is at least as successful, feasible, effective and safe as a TPCL cholecystectomy. Surgeons performing SILS should have a firm foundation of advanced minimal access surgical skills and a cautious, gradated approach to attempt the various procedures. Prospective randomized studies comparing single access versus conventional multiport laparoscopic cholecystectomy, with large volumes and long-term followup, are needed to confirm our initial experience. (ClinicalTrials.gov Identifier:NCT01772745.)