IDEAL CELL-DECOMPOSITIONS FOR A HYPERBOLIC SURFACE AND EULER CHARACTERISTIC

Sozen, Yasar Korean Mathematical Society 2008 대한수학회지 Vol.45 No.4

In this article, we constructively prove that on a surface S with genus g$\geq$2, there exit maximal geodesic laminations with 7g-7,...,9g-9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g-7,...,9g-9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F-E+V, where F, E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal cell decompositions.

A sensor for confident identification of structural damage in reinforced concrete buildings

Sozen, Mete A.,Pujol, Santiago Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.3

A specific type of structural damage that would benefit from remote sensing is discussed and a solution is suggested.

Determination of displacement distributions in welded steel tension elements using digital image techniques

Sahin Sozen 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.5

It is known that material properties, connection quality and manufacturing methods are among the important factors directly affecting the behavior of steel connections and hence steel structures. The possible performance differences between a fabricated connection and its computer model may cause critical design problems for steel structures. Achieving a reliable design depends, however, on how accurately the material properties and relevant constitutive models are considered to characterize the behavior of structures. Conventionally, the stress and strain fields in structural steel connections are calculated using the finite elements method with assumed material properties and constitutive models. Because the conventional strain gages allow the measurement of deformation only at one point and direction for specific time duration, it is not possible to determine the general characteristics of stress-strain distributions in connections after the laboratory performance tests. In this study, a new method is introduced to measure displacement distribution of simple steel welded connections under tension tests. The method is based on analyzing digital images of connection specimens taken periodically during the laboratory tension test. By using this method, displacement distribution of steel connections can be calculated with an acceptable precision for the tested connections. Calculated displacements based on the digital image correlation method are compared with those calculated using the finite elements method.

Ideal cell-decompositions for a hyperbolic surface and Euler characteristic

Yasar Sozen 대한수학회 2008 대한수학회지 Vol.45 No.4

In this article, we constructively prove that on a surface S with genus g ≥ 2, there exit maximal geodesic laminations with 7g - 7,..., 9g - 9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g - 7,..., 9g - 9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F - E+V, where F,E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal celldecompositions. In this article, we constructively prove that on a surface S with genus g ≥ 2, there exit maximal geodesic laminations with 7g - 7,..., 9g - 9 leaves. Thus, S can have ideal cell-decompositions (i.e., S can be (ideally) triangulated by maximal geodesic laminations) with 7g - 7,..., 9g - 9 (ideal) 1-cells. Once there is a triangulation for a compact surface, the Euler characteristic for the surface can be calculated as the alternating sum F - E+V, where F,E, and V denote the number of faces, edges, and vertices, respectively. We also prove that the same formula holds for the ideal celldecompositions.

ON A GENERALIZATION OF ⊕-CO-COATOMICALLY SUPPLEMENTED MODULES

ESRA OZTURK SOZEN,FIGEN ERYILMAZ 호남수학회 2023 호남수학학술지 Vol.45 No.1

In this paper, we define ⊕δ-co-coatomically supplemented and co-coatomically δ-semiperfect modules as a strongly notion of ⊕- co-coatomically supplemented and co-coatomically semiperfect modules with the help of Zhou’s radical. We say that a module A is ⊕δ-cocoatomically supplemented if each co-coatomic submodule of A has a δ−supplement in A which is a direct summand of A. And a module A is co-coatomically δ-semiperfect if each coatomic factor module of A has a projective δ-cover. Also we define co-coatomically amply δ-supplemented modules and we examined the basic properties of these modules. Furthermore, we give a ring characterization for our modules. In particular, a ring R is δ-semiperfect if and only if each free R-module is co-coatomically δ-semiperfect.

REIDEMEISTER TORSION AND ORIENTABLE PUNCTURED SURFACES

Dirican, Esma,Sozen, Yasar Korean Mathematical Society 2018 대한수학회지 Vol.55 No.4

Let ${\Sigma}_{g,n,b}$ denote the orientable surface obtained from the closed orientable surface ${\Sigma}_g$ of genus $g{\geq}2$ by deleting the interior of $n{\geq}1$ distinct topological disks and $b{\geq}1$ points. Using the notion of symplectic chain complex, the present paper establishes a formula for computing Reidemeister torsion of the surface ${\Sigma}_{g,n,b}$ in terms of Reidemeister torsion of the closed surface ${\Sigma}_g$, Reidemeister torsion of disk, and Reidemeister torsion of punctured disk.

A Hierarchical Solution Approach for Occupational Health and Safety Inspectors' Task Assignment Problem

Arikan, Feyzan,Sozen, Songul K. Occupational Safety and Health Research Institute 2021 Safety and health at work Vol.12 No.2

Background: Occupational health and safety (OHS) is a significant interest of all governments to prevent workplace hazards. Although appropriate legislation and regulations are essentials for the protection of workers, they are solely not enough. Application of them in practice should be secured by an efficient inspection system. Fundamental components of an inspection system are inspectors and their audit tasks. Maintaining the fair balanced task assignment among inspectors strictly enhances the efficiency of the overall system. Methods: This study proposes a two-phased goal programming approach for OHS inspectors' task assignments and presents a case study. Results: The solution approach gives the balanced assignment of inspectors to the workplaces in different cities of the country in the planning period. The obtained schedule takes into account the distances covered by the work places and the number of the workplaces' employees to be audited and pays attention to the human factors by considering the preferences of the inspectors. The comparisons between the obtained optimal schedule and the implemented one that is produced manually show that the approach not only maintains the technical requirements of the problem, but also provides social and physical balance to the task assignment. Conclusion: Both the approach and the application study are expected to offer fruitful inspirations in the area of safety management and policy and they provide a good guide for social policy and organizational aspects in the field of OHS inspectors' task assignment.

Reidemeister torsion and orientable punctured surfaces

Esma Dirican,Yasar Sozen 대한수학회 2018 대한수학회지 Vol.55 No.4

Let $\Sigma_{g,n,b}$ denote the orientable surface obtained from the closed orientable surface $\Sigma_g$ of genus $g\geq2$ by deleting the interior of $n\geq 1$ distinct topological disks and $b\geq 1$ points. Using the notion of symplectic chain complex, the present paper establishes a formula for computing Reidemeister torsion of the surface $\Sigma_{g,n,b}$ in terms of Reidemeister torsion of the closed surface $\Sigma_{g},$ Reidemeister torsion of disk, and Reidemeister torsion of punctured disk.

Mean Platelet Volume Could be a Possible Biomarker for Papillary Thyroid Carcinomas

Baldane, Suleyman,Ipekci, Suleyman H,Sozen, Mehmet,Kebapcilar, Levent Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.7

Thyroid cancer is the most prevalent endocrine cancer and is evident in nearly 5% of thyroid nodules. The correlation between mean platelet volume (MPV) and many other cancer types has been investigated previously. However, the correlation between papillary thyroid carcinoma (PTC) and MPV has not yet been studied in detail. The aim of this study was to examine whether MPV would be a useful inflammatory marker to differentiate PTC patients from cases of benign goiter and healthy controls. Preoperative MPV levels in patients with PTC were found to be significantly higher when compared with benign goiter patients and healthy controls ((respectively, 8.05 femtoliter (fl), 7.57 fl, 7.36 fl, p=0.001). After surgical treatment of PTC patients, a significant decrease in MPV levels was seen (8.05 fl versus 7.60 fl, p=0.005). ROC analysis suggested 7.81 as the cut-off value for MPV (AUC=0.729, sensitivity 60%, specificity 80%). In conclusion, maybe changes in MPV levels can be used as an easily available biomarker for monitoring the risk of PTC in patients with thyroid nodules, enabling early diagnosis of PTC.

Prognostic Value of Preoperative Inflammation-Based Prognostic Scores on Hospital Mortality after Gastric Cancer Surgery

Dinc, Tolga,Yildiz, Baris Dogu,Kayilioglu, Ilgaz,Sozen, Isa,Tez, Mesut,Coskun, Faruk Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.18

Gastric cancer is the fourth most common malignancy worldwide. Poor prognosis in gastric cancer is linked with hypoalbuminemia. Previous studies demonstrated relationships between gastric cancer and chronic inflammation. The aim of this study was to assess the prognostic value of preoperative inflammation-based prognostic scores regarding hospital mortality after gastrectomy. Unlike other recent articles on the same topic; we could only verify prognostic value of prognostic nutritional index for in hospital mortality after surgery.