172 research outputs found
Performance improvements for unplanned high density wireless LANs
No full textChaotic unplanned IEEE 802.11 WLAN deployments are becoming the norm and such residential deployments have many nearby access points (APs) and stations on the same channel, either due to lack of coordination or insufficient available channels. Thus, inter-cell interference in these high-density settings is common but not well-understood. Our evaluations for such interfering deployments reveal that up-to two-thirds of the WLAN system capacity may be lost in a typical large-apartment building with 50 interfering WLANs In this thesis, we first report on our analysis of high-density unplanned WLANs' performance under realistic scenarios. We find that with a typical TCP-dominant workload, cumulative system throughput is characterized by the number of actively interfering APs rather than the number of clients. We verify that due to TCP flow control, the number of backlogged stations in such a network equals twice the number of active APs. Thus, a single AP network proves very robust even with over one hundred clients, while multiple interfering APs lead to a significant increase in collisions that reduces throughput and affects multimedia traffic. Based on our analysis, we suggest a practical contention window adaptation technique, WiPhi, using information on the number of nearby APs rather than clients. We also point out the need for collision-resilient rate adaptation in such a setting. Together these techniques can largely recover the loss in cumulative throughput in a setting with strongly interfering APs. We then propose an alternative ISP-level solution, HeedNet, recovering lost performance by scheduling the IP packets of the bulk traffic at the ISP edge-router towards interfering APs. It requires no changes to the MAC protocol and the APs of the network, making it a viable solution for ISPs. We evaluate HeedNet via simulations and an actual deployment to show that a significant portion of the lost system capacity can be regained (more than 2.2X improvement compared to legacy). HeedNet also increases the fairness, reducing starvation among WLANs. Additionally, we show that HeedNet improves the performance of the non-scheduled (i.e., non-bulk) traffic considerably, such as VoIP, due to the reduced-collision rate environment it creates.Ph.D.Includes bibliographical referencesIncludes vitaby Mesut Ali Ergi
Measuring the service quality of student affairs at higher education and an examplary application of it
No full textKumru, Mesut (Dogus Author) -- Yıldız Kumru, Pınar (Dogus Author)Due to its main characteristics of intangibility, inseparability, heterogeneity andperishability, it is quite difficult to describe and measure the service quality in general. A number of methods have been developed to measure service quality in the application areas. As one of these methods, SERVQUAL is to be used in this study to measure the service quality of student affairs at higher education and the gaps between expected service and perceived performance for the service beneficiaries are derived.Hacettepe Üniversitesi, Valör Kongre Organizasyonlar
Kurumsal performans değerlendirmenin önemi, gelişimi ve uygulama örnekleri
No full textKumru, Mesut (Dogus Author) -- Conference full title: Yöneylem Araştırması ve Endüstri Mühendisliği 32. Ulusal Kongresi - YAEM 2012, 20-22 Haziran, İstanbul: Doğuş Üniversitesi.Kurumsal performans yönetimi, firmaların daha başarılı ve rakiplerinin önünde olabilmek için uyguladıkları bir yönetim şeklidir. Bu yönetim şekli, stratejilerin tanımlanarak uygulanmasına ve sürekli performans iyileştirmeleri ve rekabet avantajı elde edilmesine yardımcı bütünleşik bir yaklaşımdır. Kurumsal performans yönetim sisteminin en önemli ayağı kurumsal planlama, kontrol ve değerlendirme alt sistemidir. Bu alt sistemin ana bileşeni kurumsal performans değerlendirme modeli olup, bu modelin yapısı planlama sisteminin veri tabanına dayandırılmakta; simülasyon modelleri, bütçeleme araçları ve ürün bilgi sistemleriyle uyumlu olmaktadır. Kurumsal performans değerlendirme modelleri firmaların özelliklerine göre farklılıklar göstermektedir. Bu modeller günümüze kadar çok değişik şekillerde tasarlanmış ve uygulanmıştır. Bu çalışmada, kurumsal performans yönetimi, kurumsal performans değerlendirme, kurumsal performans değerlendirmenin gelişimi, modeller (finansal bazlı modeller, dengeli modeller, mükemmeliyet modelleri, vb.), yurt içi ve yurt dışından kurumsal performans değerlendirme uygulama örnekleri yer almaktadır.Arçelik, Bosch, Pegasus, LG, Ekol, Borçelik, Ford Otosan, Casino Uzman
Research on A1 irregularity status in different spectral acceleration coefficients on reinforced concrete structures
No full textMurat YakarMost of the building damages in our country are caused by earthquakes. As known, the properties of the building are determinant in the magnitude of the earthquake forces that cause these damages. Thus, selection of the structural system is crucial in the design process. In case of any irregularity in the building, load transfer will not be provided safely. In the Turkish Earthquake Code, related irregularities are analysed under two groups. Group A indicates the irregularities in the plan, and Group B represents vertical irregularities. Irregularities in the plan include A1 Torsional Irregularities; A2 Floor Discontinuities; and A3 Bulges in the Plan. In this study, A1 irregularity status in the reinforced concrete structure was analysed for different spectral acceleration coefficients. The purpose of the study is to understand the change of torsional irregularity coefficient in different spectral acceleration coefficients. As a result, in a typical building with the same geometric and stiffness properties, the torsional irregularity coefficient is not changed for different earthquake zones. Also, the importance of the location of the shear wall elements in the plan was once again emphasized. © Author(s) 2021
Neural networks and search for minimum defectiveness in molding operation in ceramic industry
No full textKumru, Mesut (Dogus Author) -- Conference full title: 2011 International Symposium on Innovations in Intelligent Systems and Applications (INISTA 2011) Istanbul, Turkey, 15 - 18 June 2011This study is to be conducted in a ceramics production plant where the highest product defectiveness occurs in the molding shop of the plant. There are a number of factors that affect the amount of product defectiveness. The purpose is to search for a set of factor treatment conditions which provide the minimum defectiveness performance in the shop. Artificial Neural Network (ANN) method was used to realize the purpose. Based on the statistical analysis, the ANN approach is found to be reliable in predicting the amount of defectiveness that depends on various factors.TUBITAK, IEEE
Two-stage reconstruction of a massive gun-shot wound of the midface with a free radial forearm flap and a parietal osteofasciocutaneous flap
No full textTreatment of midface gunshot injuries and their reconstruction remains one of the difficult problems of reconstructive surgery. Several flaps have been described for the reconstruction of total lip and nasal defects. We present a case of a gunshot wound to the midface in which a two-stage procedure was performed. In the first stage, a free radial forearm flap was successfully transferred for the reconstruction of the total nose. In the second stage, total upper lip reconstruction was achieved using a parietal osteofasciocutaneous flap pedicled to the parietotemporal fascia based on the superficialis temporal artery. At a mean follow-up period of 18 months, near-normal functional and cosmetic results were obtained. © Springer-Verlag 2004
Analysis of employee satisfaction in an automotive spare parts manufacturing company
No full textKumru, Mesut (Dogus Author) -- Conference full title: 37. Yöneylem araştırması ve Endüstri Mühendisliği Ulusal Kongresi; Yıldız Teknik Üniversitesi, İstanbul, 5-7 Temmuz 2017Otomotiv yan sanayiinin lider firmalarından birisinde çalışan memnuniyeti incelenmiştir. Bu maksatla bir anket düzenlenmiş, bu anketle çalışanların işyerindeki fiziksel çalışma ortamından, yaptıkları işlerden, iş arkadaşlarından, çalıştıkları şirketten, amirlerinden, genel şirket yönetimi ve eğitim programlarından memnun olup olmadıkları konusunda bilgi edinilmeye çalışılmıştır. Sözü edilen organizasyonel faktörlere ilaveten kişisel faktörler olarak yaş, cinsiyet, hizmet süresi, statü ve eğitim durumu incelenmiştir. Söz konusu değişkenlerin çalışan memnuniyeti düzeyine etkileri araştırılmıştır. Çalışanların sözü edilen faktörlerden memnuniyet düzeyleri ile demografik özelliklerinin ilişkisi parametrik olmayan ki-kare testiyle incelenmiştir. Bu çerçevede oluşturulan dokuz hipotez test edilmiştir. Ayrıca, yapılan iş ve çalışılan şirketle ilgili bazı hususlar yedi ana faktörle ilişkilendirilmeye çalışılmış, örnek regresyon bağıntıları ortaya konulmuştur
Respiratory findings in gun factory workers exposed to solvents
No full textAbstractObjective: Gun factory workers are exposed to many solvents (toluene, acetone, butanol, xylene, benzene, trichloroethylene). We investigated whether chronic exposure to solvents had adverse effect on respiratory system.Material and methods: The workers were questionnaired by modified Medical Research Council's respiratory questionnaire before morning start shift. Then physical examination and measurement of pulmonary functions by portable dry rolling spirometer were performed. The study group consisted of 1091 gun factory workers. The workers were grouped according to their smoking habits (smokers, [exposed n: 353 vs. unexposed n: 339] and non-smokers [exposed n: 58 vs. unexposed n: 341]). Asthma-related symptoms were defined as either definite asthma, probable asthma, and possible asthma.Results: In non-smokers, the report of asthma-related symptoms was more prevalent in exposed workers than unexposed (39.7% vs. 21.7% OR 2.4[1.3–4.3], respectively P=0.003). In smokers, the report of asthma-related symptoms was more common in exposed group than unexposed (50.7% vs. 42.5% OR 1.4[1.0–1.9], respectively P=0.03). Logistic regression analysis showed that smoking (OR 2.8 [2.0–3.8] P=0.00001) and exposure to solvents (OR 1.4[1.1–1.9] P=0.01) were independent risk factors for asthma-related symptoms, after adjusting for age. Logistic regression analysis identified that smoking (OR 3.3[2.3–4.6] P=0.00001) was independent risk factors for chronic bronchitis. Multiple linear regression analysis of lung-function parameters (% forced expiratory volume (FEV1), FEV1/forced vital capacity, FEF25–75) indicated significant effects of smoking.Conclusion: Present study indicated significant effects of smoking and exposure to solvents, with the smoking effect being the most important on asthma-related symptoms of gun factory workers
The Opinions of the Instructors about the Listening Skills of Syrian Students Learning Turkish
No full textAbstract In this study, the opinions of the instructors giving Turkish courses based on listening skills for th
Multi-Stream Word-Based Compression Algorithm for Compressed Text Search
No full textOzturk, Emir (Trakya author)
Mesut, Altan (Trakya author)In this article, we present a novel word-based lossless compression algorithm for text files using a semi-static model. We named this method the Multi-stream word-based compression algorithm (MWCA)' because it stores the compressed forms of the words in three individual streams depending on their frequencies in the text and stores two dictionaries and a bit vector as side information. In our experiments, MWCA produces a compression ratio of 3.23 bpc on average and 2.88 bpc for files greater than 50 MB; if a variable length encoder such as Huffman coding is used after MWCA, the given ratios are reduced to 2.65 and 2.44 bpc, respectively. MWCA supports exact word matching without decompression, and its multi-stream approach reduces the search time with respect to single-stream algorithms. Additionally, the MWCA multi-stream structure supplies the reduction in network load by requesting only the necessary streams from the database. With the advantage of its fast compressed search feature and multi-stream structure, we believe that MWCA is a good solution, especially for storing and searching big text data
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