108 research outputs found
Quality assessment of 3D building data
No full textThis project has been funded by Ordnance Survey Research, the research and development department of the Ordnance Survey of Great Britain, which is gratefully acknowledged. The first author, Devrim Akca, was formerly with the Institute of Geodesy and Photogrammetry of ETH Zurich, Switzerland.Three-dimensional building models are often now produced from lidar and photogrammetric data. The quality control of these models is a relevant issue both from the scientific and practical points of view. This work presents a method for the quality control of such models. The input model (3D building data) is co-registered to the verification data using a 3D surface matching method. The 3D surface matching evaluates the Euclidean distances between the verification and input data-sets. The Euclidean distances give appropriate metrics for the 3D model quality. This metric is independent of the method of data capture. The proposed method can favourably address the reference system accuracy, positional accuracy and completeness. Three practical examples of the method are provided for demonstration.This project has been funded by Ordnance Survey Research, the research and development department of the Ordnance Survey of Great Britain, which is gratefully acknowledged. The first author, Devrim Akca, was formerly with the Institute of Geodesy and Photogrammetry of ETH Zurich, Switzerlanddepartment of the Ordnance Survey of Great BritainPublisher's Versio
Enhancement of Pem Fuel Cell Performance at Higher Temperatures and Lower Humidities by High Performance Membrane Electrode Assembly Based on Nafion/Zeolite Membrane
No full textDEVRIM, YILSER/0000-0001-8430-0702This work reports the preparation of Nafion/zeolite composite membranes with different zeolite loading. The structure of the Nafion/zeolite composite membranes are investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and by thermogravimetric analysis (TGA). The introduction of zeolite particles into the Nafion matrix helps to improve the water uptake, proton conductivity and thermal stability of the nanocomposite membranes compared to the virgin Nafion membrane. The SEM analyses have proved the uniform and homogeneous distribution of zeolite in composite membranes. The composite membranes are tested in a single PEMFC with a 5 cm(2) active area operating at the temperature range of 75-120 degrees C and in humidified under 50% relative humidity (RH) and fully humidified conditions. Single PEMFC tests show that Nafion/zeolite composite membrane is more stable and also performed better than virgin Nafion membrane at low humidity condition. The results indicate the Nafion/zeolite composite membranes could be utilized as the proton exchange membranes for PEMFC. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Atilim University Research project [ATU-LAP-SD-1314-02]This study is supported by Atilim University Research project ATU-LAP-SD-1314-02. The author gratefully acknowledge to TEKSIS (METU Technopolis, TURKEY) for their support during MEA preparation
Computing Reliability Indices of a Wind Power System Via Markov Chain Modelling of Wind Speed
No full textDEVRIM, YILSER/0000-0001-8430-0702; Eryilmaz, Serkan/0000-0002-2108-1781Statistical modelling of wind speed is of great importance in the evaluation of wind farm performance and power production. Various models have been proposed in the literature depending on the corresponding time scale. For hourly observed wind speed data, the dependence among successive wind speed values is inevitable. Such a dependence has been well modelled by Markov chains. In this paper, the use of Markov chains for modelling wind speed data is discussed in the context of the previously proposed likelihood ratio test. The main steps for Markov chain based modelling methodology of wind speed are presented and the limiting distribution of the Markov chain is utilized to compute wind speed probabilities. The computational formulas for reliability indices of a wind farm consisting of a specified number of wind turbines are presented through the limiting distribution of a Markov chain. A case study that is based on real data set is also presented.Scientific and Technological Research Council of Turkey (TUBITAK) [TUBITAK 1001-119F182]The author(s) disclosed receipt of the following finan-cial support for the research, authorship, and/or publi-cation of this article: This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under project TUBITAK 1001-119F182
Outcome of metastatic colorectal cancer patients receiving palliative chemotherapy in Marmara University Hospital
No full textGraphene Based Catalyst Supports for High Temperature Pem Fuel Cell Application
No full textDEVRIM, YILSER/0000-0001-8430-0702In this study, the effect of graphene nanoplatelet (GNP) and graphene oxide (GO) based carbon supports on polybenzimidazole (PBI) based high temperature proton exchange membrane fuel cells (HT-PEMFCs) performances were investigated. Pt/GNP and Pt/GO catalysts were synthesized by microwave assisted chemical reduction support. X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Brauner, Emmet and Teller (BET) analysis and high resolution transmission electron microscopy (HRTEM) were used to investigate the microstructure and morphology of the as-prepared catalysts. The electrochemical surface area (ESA) was studied by cyclic voltammetry (CV). The results showed deposition of smaller Pt nanoparticles with uniform distribution and higher ECSA for Pt/GNP compared to Pt/GO. The Pt/GNP and Pt/GO catalysts were tested in 25 cm(2) active area single HT-PEMFC with H-2/air at 160 degrees C without humidification. Performance evaluation in HT-PEMFC shows current densities of 0.28, 0.17 and 0.22 A/cm(2) for the Pt/GNP, Pt/C and Pt/GO catalysts based MEAs at 160 degrees C, respectively. The maximum power density was obtained for MEA prepared by Pt/GNP catalyst with H-2/Air dry reactant gases as 0.34, 0.40 and 0.46 W/cm(2) at 160 degrees C, 175 degrees C and 190 degrees C, respectively. Graphene based catalyst supports exhibits an enhanced HT-PEMFC performance in both low and high current density regions. The results indicate the graphene catalyst support could be utilized as the catalyst support for HT-PEMFC application. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.TEKSIS (METU Technopolis, TURKEY)The author gratefully acknowledges TEKSIS (METU Technopolis, TURKEY) for their support during MEA preparation. The authors would like to thank at METU Central Laboratory for TGA, XRD, BET and HRTEM analysis
Outcome of adjuvant treatment in turkish breast cancer (BC) patients (PTS): Single institution experience
No full textClinical Outcome of Turkish Metastatic Breast Cancer Patients with Currently Available Treatment Modalities - Single Center Experience
No full textBackground: Breast cancer is the most common malignancy and the second leading cause of cancer-related death among women in the developed countries. Despite advances in screening, improved local therapies and adjuvant systemic treatments, median survival of metastatic breast cancer patients (MBC) is in the range of 2-3 years at most. We aimed to investigate whether the prognostic factors and therapeutic responses of our Turkish patients are similar to those in the literature. Materials and Methods: We reviewed the medical records of MBC patients who had been treated in our institution between 1999-2009 and analyzed their clinicopathological features and survival outcomes retrospectively Results: A hundred and sixty patients were included. Median age was 47 (23-82), median follow up was 24 (2-186) months. At the time of diagnosis 59% of patients were under the age of 50 and 46% were postmenopausal. The majority (37%) had multiple sites of metastases. Forty percent received endocrine therapy and 40% chemotherapy as first line metastatic treatment. Thirty (20%) patients were treated with molecular targeting agents like trastuzumab, lapatinib and sunitinib, frequently combined with a chemotherapy agent. Five-year overall survival (OS) was 32% and median OS was 38 months for the whole group. Five year progression free survival (PFS) was 10% and median PFS was 10 months. Menopausal status, hormone receptor expression and disease free status had a significant impact on overall survival in the multivariate analysis (p 0.018, p 0.018 and p:0.003, respectively). Conclusions: All our patients were treated with the modern oncologic therapies recommended by the international guidelines. From our data, MBC patients live up to 3-4 years, indicating that further improvement beyond that requires development of new treatment modalities. The survival outcomes of our patients were consistent with the data reported in the literature
Docetaxel, cisplatin, and 5-fluorouracil-based induction chemotherapy followed by concurrent chemoradiotherapy with cisplatin in locally advanced stage III and IV nasopharyngeal cancer.
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