CFD to Quantify Idealized Intra-Aneurysmal Blood Flow in Response to Regular and Flow Diverter Stent Treatment

Cerebral aneurysms are pathological dilatations of the vessels supplying the brain. They carry a certain risk of rupture, which in turn, results in a high risk of mortality and morbidity. Flow diverters (FDs) are high-density meshed stents which are implanted in the vessel segment harboring an intracranial aneurysm to cover the entrance of the aneurysm, thus reducing the blood flow into the aneurysm, promoting thrombosis formation and stable occlusion, which prevents rupture or growth of the aneurysm. In the present study, the blood flow in an idealized aneurysm, treated with an FD stent and a regular stent (RS), were modeled and analyzed considering their design, surface area porosity, and flow reduction to investigate the quantitative and qualitative effect of the stent on intra-aneurysmal hemodynamics. CFD simulations were conducted before and after treatment. Significant reductions were observed for most hemodynamic variables with the use of stents, during both the peak systolic and late diastolic cardiac cycles. FD reduces the intra-aneurysmal wall shear stress (WSS), inflow, and aneurysmal flow velocity, and increases the turnover time when compared to the RS;therefore, the possibility of aneurysm thrombotic occlusion is likely to increase, reducing the risk of rupture in cerebral aneurysms

Accounting education in Turkey: The case of the Turkey Accounting Education SymposiumTürkiye’de muhasebe eğitimi: Türkiye Muhasebe Eğitimi Sempozyumu örneği

The Turkey Accounting Education Symposium is held with a specific theme almost every year since 1979. Between the years 2005-2015, the symposiums are held with themes like: current changes in accounting environment, international accounting standards, globalization, entrepreneurs expectations, and accounting in digital age etc. Literatur review, investigation and research papers have been presented at the symposiums which is organized rooted universities in Turkey. Paper writers made research on faculty and students from several universities by surveys. Additionally, papers about current changes in accounting, usage of information systems in accounting education, and innovations in accounting have been presented. When papers examined, it is possible to reach to conclusion that accounting education must be configured in accordance with the requirements of the age, technological developments, international standards and developments. The Turkey Accounting Education Symposium in which accounting education trends and problems were discussed is one of the symposium that academics in education institutions offering accounting education and other interested parties are attended in Turkey. The aim of this study is to introduce changes in the accounting education in Turkey by examining the presented papers at the symposium. In this study, a biography have been revealed on papers presented at The Turkey Accounting Education Symposium between the years 2005-2015. Presented papers at the symposium for every year are examined and findings are evaluated in the study. Özet1979 yılından günümüze hemen her yıl Türkiye Muhasebe Eğitimi Sempozyumu belirli bir tema ile düzenlenmektedir. 2005-2015 yılları arasındaki sempozyumlar muhasebe ortamındaki güncel gelişmeler, uluslararası muhasebe standartları, küreselleşme, işletme beklentileri ve dijital çağda muhasebe gibi temalarla düzenlenmiştir. Türkiye’deki köklü üniversitelerin ev sahipliğini yaptığı sempozyumlarda literatür taraması, inceleme ve araştırma niteliğinde bildiriler sunulmuştur. Bildiri yazarları çeşitli üniversitelerdeki öğretim üyeleri ve öğrencilere uyguladıkları anketler aracılığıyla muhasebe eğitimine ilişkin araştırmalar yapmışlardır. Ayrıca muhasebe alanındaki gelişmeler, bilgi sistemlerinin muhasebe eğitiminde kullanılması ve muhasebe eğitiminde yenilikler üzerine bildiriler sunulmuştur. Bildiriler incelendiğinde, muhasebe eğitiminin çağın gereklerine, teknolojik gelişmelere, uluslararası düzeydeki standart ve gelişmelere göre yapılandırılması gerektiği sonucuna ulaşmak mümkündür. Türkiye Muhasebe Eğitimi Sempozyumu, muhasebe eğitimi veren öğretim kurumlarındaki akademisyenlerin ve diğer ilgi duyanların katıldığı, muhasebe eğitimindeki trendlerin ve karşılaşılan sorunların tartışıldığı önemli faaliyetlerden birisidir. Bu çalışmanın amacı Türkiye Muhasebe Eğitimi Sempozyumu’nda sunulan bildirilerin içerik analizi ile yıllar içinde Türkiye’de muhasebe eğitimi konusundaki değişimin ortaya konulmasıdır. Bu çalışmada, Türkiye Muhasebe Eğitimi Sempozyumu’nda 2005-2015 yılları arasında sunulan bildirilerin bir biyografisi çıkarılmıştır. Yıllar itibariyle sempozyumda sunulan bildiriler incelenmiş ve bulgular değerlendirilmiştir

Multi-objective integer programming: An improved recursive algorithm

This paper introduces an improved recursive algorithm to generate the set of all nondominated objective vectors for the Multi-Objective Integer Programming (MOIP) problem. We significantly improve the earlier recursive algorithm of \"Ozlen and Azizo\u{g}lu by using the set of already solved subproblems and their solutions to avoid solving a large number of IPs. A numerical example is presented to explain the workings of the algorithm, and we conduct a series of computational experiments to show the savings that can be obtained. As our experiments show, the improvement becomes more significant as the problems grow larger in terms of the number of objectives.Comment: 11 pages, 6 tables; v2: added more details and a computational stud

Accounting education and quality dimensions: A field research in TurkeyMuhasebe eğitimi ve kalite boyutları: Türkiye alan araştırması

Rules, regulations and operating characteristics regarding the accounting information system which they use during the life work are transferred to the individuals with the conception of lifelong learning in the accounting education. In this way, individuals acquires sufficient accounting information in their professional careers and professional exams. No doubt, the success is directly related to personal competencies of individuals and the quality of education received. The quality of accounting education is concerned with the level of realization of the expectations from the individuals who take or took accounting education. This study focuses on education quality dimensions referring to accounting education. The aim of this study is to contribute to the literature on the quality of accounting education by examining periodicals on the scope and quality of accounting education made in Turkey. In studies conducted in Turkey, it is investigated that the expectations of students and businesses from accounting education and the quality dimensions held by the universities such as the number of lecturers, course duration, and physical facilities. ÖzetHayat boyu öğrenme anlayışı ile muhasebe eğitiminde, bireylere çalışma hayatı süresince kullanacakları, muhasebe bilgi sistemine ilişkin kural, yasal düzenleme ve işleyiş özellikleri aktarılmaktadır. Bu sayede bireyler profesyonel kariyerlerinde ve mesleki sınavlarda yeterli muhasebe bilgisi edinmektedir. Şüphesiz ki muhasebe eğitimi alan bireylerin profesyonel kariyerlerinde ve mesleki sınavlardaki başarısı kişisel yetkinlikler ve alınan eğitimin kalitesiyle doğrudan ilgilidir. Muhasebe eğitiminde kalite; muhasebe eğitimiyle hem eğitim alanların hem de muhasebe eğitimi almış kişilerden beklentilerin karşılanma düzeyiyle ilgilidir. Bu çalışmada muhasebe eğitimine değinilerek eğitimde kalite boyutları üzerinde durulmaktadır. Bu çalışmanın amacı, Türkiye’de yapılmış muhasebe eğitimi ve kalite kapsamında süreli yayınlar incelenerek muhasebe eğitim kalitesi üzerine literatüre katkı sağlanmasıdır. Türkiye’de yapılmış çalışmalarda öğrencilerin ve işletmelerin muhasebe eğitiminden beklentileri, üniversitelerin sahip olduğu öğretim üyesi, ders süreleri, ve fiziki imkanlar gibi kalite boyutlarının araştırıldığı görülmektedir

Optimising a nonlinear utility function in multi-objective integer programming

In this paper we develop an algorithm to optimise a nonlinear utility function of multiple objectives over the integer efficient set. Our approach is based on identifying and updating bounds on the individual objectives as well as the optimal utility value. This is done using already known solutions, linear programming relaxations, utility function inversion, and integer programming. We develop a general optimisation algorithm for use with k objectives, and we illustrate our approach using a tri-objective integer programming problem.Comment: 11 pages, 2 tables; v3: minor revisions, to appear in Journal of Global Optimizatio

Inverse multiple criteria sorting problem

International audienc

Portfolio decision analysis with a generalized balance approach

International audienceWe consider a resource allocation problem in which the decision maker is responsible for selecting a group of projects to generate a portfolio, with the aim of maximizing the total benefit, and distributing the budget in a balanced way across different categories. We assume that the decision maker defines an interval for the desired share of each category. We propose augmented -constraint method to generate the nondominated solutions considering two objective functions: total benefit and balance among categories. The solution time increases with the problem size, and augmented -constraint method fails to find all nondominated solutions. We therefore develop a variable neighborhood search algorithm for the purpose of generating the nondominated frontier. Our computational experiments show that the nondominated frontier can be accurately estimated with respect to different performance measures

An interactive algorithm for multiple criteria constrained sorting problem

International audienc

Esnek imalat sistemlerinde paylaştırma ve makine ucu kararları.

In this thesis, we consider a capacity allocation problem in flexible manufacturing systems. We assume limited time and tool magazine capacities on the Computer Numerically Controlled (CNC) machines. We have a set of operations that have to be assigned to the machines and each operation requires a set of tools to be processed. Our problem is to allocate the available capacity of the CNC machines to operations and their required tools. We consider two problems in this study: maximizing the total weight of operations where there are a limited number of tools of each type available and maximizing total weight minus total tooling cost where the tools can be used or purchased at a cost. We model the problems as Integer Linear Programs and show that they are NP-hard in the strong sense. For the total weight problem, we propose upper bounds, branch and bound algorithm for exact solutions and several heuristics for approximate solutions. For the bicriteria problem, we use Lagrangean relaxation technique to obtain lower and upper bounds. Our computational results have revealed that all solution approaches give satisfactory results in reasonable times.Ph.D. - Doctoral Progra