Robust network design under polyhedral traffic uncertainty

Ankara : The Department of Industrial Engineering and The Institute of Engineering and Science of Bilkent Univ., 2007.Thesis (Ph.D.) -- Bilkent University, 2007.Includes bibliographical references leaves 160-166.In this thesis, we study the design of networks robust to changes in demand estimates. We consider the case where the set of feasible demands is defined by an arbitrary polyhedron. Our motivation is to determine link capacity or routing configurations, which remain feasible for any realization in the corresponding demand polyhedron. We consider three well-known problems under polyhedral demand uncertainty all of which are posed as semi-infinite mixed integer programming problems. We develop explicit, compact formulations for all three problems as well as alternative formulations and exact solution methods. The first problem arises in the Virtual Private Network (VPN) design field. We present compact linear mixed-integer programming formulations for the problem with the classical hose traffic model and for a new, less conservative, robust variant relying on accessible traffic statistics. Although we can solve these formulations for medium-to-large instances in reasonable times using off-the-shelf MIP solvers, we develop a combined branch-and-price and cutting plane algorithm to handle larger instances. We also provide an extensive discussion of our numerical results. Next, we study the Open Shortest Path First (OSPF) routing enhanced with traffic engineering tools under general demand uncertainty with the motivation to discuss if OSPF could be made comparable to the general unconstrained routing (MPLS) when it is provided with a less restrictive operating environment. To the best of our knowledge, these two routing mechanisms are compared for the first time under such a general setting. We provide compact formulations for both routing types and show that MPLS routing for polyhedral demands can be computed in polynomial time. Moreover, we present a specialized branchand-price algorithm strengthened with the inclusion of cuts as an exact solution tool. Subsequently, we compare the new and more flexible OSPF routing with MPLS as well as the traditional OSPF on several network instances. We observe that the management tools we use in OSPF make it significantly better than the generic OSPF. Moreover, we show that OSPF performance can get closer to that of MPLS in some cases. Finally, we consider the Network Loading Problem (NLP) under a polyhedral uncertainty description of traffic demands. After giving a compact multicommodity formulation of the problem, we prove an unexpected decomposition property obtained from projecting out the flow variables, considerably simplifying the resulting polyhedral analysis and computations by doing away with metric inequalities, an attendant feature of most successful algorithms on NLP. Under the hose model of feasible demands, we study the polyhedral aspects of NLP, used as the basis of an efficient branch-and-cut algorithm supported by a simple heuristic for generating upper bounds. We provide the results of extensive computational experiments on well-known network design instances.Altın, AyşegülPh.D

Yüksek Dereceli Kasa İnvaze Olmayan Mesane Tümörlerinde Histolojik Derecelendirme Oranının Progresyona Etkisi

Aim: Histopathological classification is one of the main prognostic factors for non-muscle invasive bladder tumors (NMIBT). Weevaluated the relationship between tumor progression and the ratio of high-grade differentiation plus other routine pathologicalparameters in NMIBT.Materials and Methods: Ninety-two patients diagnosed with high grade NIMBT were analyzed between 2010-2018. Demographicinformation, tumor size, localization, multicentricity, and recurrence/progression situation were evaluated retrospectively. The high/lowgrade percentage ratio of tumor cells, tumor stage, differentiation, necrosis, lamina-propria invasion, lymphovascular invasion, andcarcinoma in-situ presence were also examined by two uro-pathologist. The effect on tumor progression was evaluated with pathologicalfindings.Results: Seventy-four (80.4%) of the patients were reported as T1 and 18 (19.6%) as Ta. The mean ratio of high-grade findings was11.9±8.5% and 69.5±28.1% for Ta and T1 patients, respectively(p25%, >50% and >75% was found to be 67(72.8%),54(58.7%) and 43(46.7%), respectively. The high-grade ratio for >25% was in only 1 Ta patient while it was in 66 of the T1patients(p75%(p50%(p=0.025).Conclusion: When evaluating the nuclear grade, defining tumors solely as high-grade leads to stratifying a highly heterogeneouspopulation in a single group. Higher rate of progression is observed in NIMBT patients with high-grade ratio >50%.KİOMT’de yüksek dereceli hücresel farklılaşma oranı ve diğer rutin patolojik parametrelerin progresyona etkisi değerlendirildi. Materyal ve Metot: Çalışmaya 2010-2018 yılları arasında transüretral mesane rezeksiyonu sonrası yüksek dereceli KİOMT tanısı alan 92 hasta dahil edildi. Hastaların demografik bilgileri, tümör çapı, lokalizasyonu, multisantrisitesi ve nüks/progresyon varlığı-süresi retrospektif olarak değerlendirildi. Ayrıca tümör hücrelerinin yüksek derece/düşük derece yüzdesi, tümör evresi, diferansiyasyon, nekroz, lamina propria invazyonu, lenfovasküler invazyon ve karsinoma in-situ varlığı iki üro-patolog tarafından incelendi. Elde edilen bulguların tümör progresyonu üzerine etkisi araştırıldı. Bulgular: Hastaların 74’ü(%80,4) T1, 18’i(%19,6) Ta olarak rapor edildi. Ta tanılı hastalarda yüksek derece oranı %11,9±8,5 iken, T1’lerde %69,5±28,1 olarak tespit edildi (p%25,>%50 ve>%75 olan hasta sayısının sırasıyla 67(%72,8), 54(%58,7) ve 43(%46,7) olduğu görüldü. Ta olan hastaların sadece 1’inde yüksek derece oranı>%25 olarak gözlenirken, T1 hastalarının 66’sında yüksek derece oranının>%25 olduğu belirlendi (p%75 olduğu görüldü. T1 yüksek derece oranları>%50 olan hastalarda progresyon, patolojik evresi T1 yüksek derece oranları %50 olan hastalarda progresyon anlamlı derecede artmaktadır

A copy-at-neighbouring-node retransmission strategy for improved wireless sensor network lifetime and reliability

A Wireless Sensor Network (WSN) is composed of tiny autonomous sensors with limited battery power. WSNs are employed to observe specific fields of interest. In this paper, we study the energy efficient and reliable network design problem using a mathematical programming framework. Energy efficiency is vital since battery replenishment is not always viable and the network lifetime is measured as the time until the first sensor exhausts its energy. Moreover, reliability is important since sensors are mostly deployed unattended and transmission of data fully and correctly is obviously critical. We develop a retransmission strategy originated from the Pareto principle and the scale-free property of complex networks. In our modified hop-by-hop reliability definition, sensors forwarding data directly to the central node must perform retransmission. Central node is the sensor with the highest data transmission load and our motivation is to secure the transmission of data passing through the central node against malicious attacks or technical failures. To this end, we present a mixed 0–1 integer programming model and an efficient heuristic. Our test results show an improvement of 80.5% in network lifetime and of 86.3% in redundant data overhead when compared with the classical conservative data redundancy approaches. We provide extensive test results, which reveal the contribution of our strategy in several other strategic design dimensions

A Literature Review on Maturity Assessment Tools Used in System Development Projects

The system development projects in the defense industry differ from the ones in other sectors with their big budgets, complexity, and provision of important capability. The organizations taking part in the acquisition process of such projects are in search of developing various kinds of mechanisms, processes, and methodologies to implement projects with better performance but with less cost and less lost time while minimizing their cost, time, and performance risk in the rapidly changing competitive environment. One of the solutions developed in this direction is maturity assessment tools. In this study, how the technology/system maturity assessment tools are used, what their benefits and limitations are, and how the system risk is calculated have been analyzed. It has been determined that the current maturity assessment tools are inadequate for calculating the system risk and that there is a need to develop a new tool/methodology that can compute the system risk. In addition, an assessment on the status of the usage of maturity assessment tools in Turkey has been made.Savunma alanındaki sistem geliştirme projeleri büyük bütçeleri, önemli yetenek kazandırmaları ve karmaşıklığı ile diğer projelerden farklılık gösterirler. Bu projelerin tedarik sürecinde yer alan organizasyonlar, hızla değişen rekabet ortamında, maliyet, zaman ve performans risklerini en aza indirgeyerek daha az kayıp süre ve daha düşük maliyetle daha yüksek performansa sahip projeleri hayata geçirebilecek mekanizmaların, süreçlerin veya metodolojilerin arayışı içindedirler. Bu doğrultuda geliştirilmiş çözümlerden bir tanesi de olgunluk değerlendirme araçlarıdır. Bu çalışmada, literatürde kullanılan teknoloji/sistem olgunluk değerlendirme araçlarının neler olduğu, metodolojileri, nasıl kullanıldıkları, faydaları ve sınırlılıkları ile sistem riskini hesaplama yönü incelenmiştir. Özellikle sistem geliştirme projelerinde kullanılan olgunluk değerlendirme araçlarının sistem riskini nasıl hesapladığına, hesaplamanın güçlü ve zayıf yönlerine cevap aranmıştır. Olgunluk değerlendirme araçlarının sistem riskini hesaplamada yetersiz oldukları tespit edilmiş ve sistem riskinin hesaplanmasına yönelik yeni bir araç ve/veya metodoloji geliştirilmesi ihtiyacı ortaya konmuştur. Ayrıca, Türkiye’de olgunluk değerlendirme araçlarının kullanım durumuyla ilgili bir değerlendirme yapılmıştır

The Effect of Sport on Tolerance Level of Secondary School Students against Themselves

The study was made with the aim of determining the effect of sport on tolerance level of secondary school students against themselves. A total of 400 students from the schools in city centre of Konya, of whom 200 do sports (100 boys and 100 girls) and 200 who don’t (100 boys and 100 girls) voluntarily participated in the study. Tolerant scale that was developed by Ersanlı in 2004, consisted of 30 items, was used to determine the participants’ tolerance level. In the evaluation of the obtained data SPSS for Windows 16 was used. After evaluating normal dispersion of the data and the homogeneous of the variances independent samples t test and One Way Anova were used to determine the significant differences and also in the differences between groups Tukey test was used. While no difference was observed in tolerance level against themselves of male secondary school students who do sport or not, significant difference was observed in the tolerance level of female students who do sport compared to female students who do not (p<0.05). When all groups were considered there was a significant difference in the tolerance level against themselves of students who do sport compared to students who do not (p<0.05). There were no significant differences according to mother and father education status, age, level of income, number of sisters/brothers, there was a significant difference according to education class (p<0.05). According to study findings it can be said that students who do sports actively are more tolerant to theirselves and to their environments than the students who don’t do sports and the girl students who do sports are more tolerant to themselves and to their environments than the girl or boy students who don’t do sport

Optimal number of routing paths in multi-path routing to minimize energy consumption in wireless sensor networks

In wireless sensor networks, multi-path routing is proposed for energy balancing which prolongs the network lifetime as compared to single-path routing where utilization of a single route between a source node and the base station results in imbalanced energy dissipation. While it is evident that increasing the number of routing paths mitigates the problem of energy over-utilization in a subset of nodes acting as relays, the net effect of the proliferation of multiple routing paths on energy balancing remains unclear. It is imperative to keep the number of routing paths as low as possible without significantly deteriorating the network lifetime; therefore, determination of the optimal number of routing paths in multi-path routing by considering the tradeoff in routing complexity and network lifetime extension is an interesting research problem. In this study, to investigate the impact of the number of routing paths in multi-path routing on network-wide energy balancing under optimal operating conditions, we build a novel mixed integer programming framework. We explore the parameter space consisting of a number of paths, number of nodes, maximum transmission range, network area, and network topology. The results of the analysis show that by utilizing the optimization scheme proposed, it is possible to achieve near-optimal energy consumption (within 1.0% neighborhood of the case where no restrictions are imposed on the number of routing paths in multi-path routing) using at most two paths for each node.Publisher's Versio

Are soluble IL-2 receptor and IL-12p40 levels useful markers for diagnosis of tuberculous pleurisy?

WOS: 000350052900006PubMed ID: 25549699Background: The differential diagnostic utilities of the levels of soluble interleukin (IL)-12p40 and the IL-2 receptor in sera and pleural effusions were evaluated in patients with exudative pleural effusions. Methods: We enrolled a total of 120 patients with exudative pleural effusions. The clinical, radiological, and histopathological diagnoses were tuberculous pleurisy in 52, malignant pleurisy in 39, and parapneumonic effusions in 29 patients. Results: We measured serum IL-12p40 and adenosine deaminase (ADA) levels in patients with tuberculous pleurisy and in a control group treated for pleural effusion to determine if such levels were useful in the diagnosis of pleural effusion (p < 0.005). Definite microbiological or histopathological diagnoses of tuberculous pleurisy or pleural effusion were recorded, and we found that ADA and serum soluble IL-2 receptor levels aided in diagnosis (p < 0.001). The levels of ADA and soluble IL-2 in pleural effusions afforded sensitivities and specificities of 84.62% and 82.69% and of 70.59% and 80.88%, respectively. The soluble IL-2 receptor level afforded a sensitivity and specificity of 82.69% and 52.9%. IL-12p40 levels in pleural effusions and sera afforded sensitivities and specifi cities of 80.77% and 80.77% and of 60.29% and 39.71%, respectively. Conclusion: Soluble IL-2 receptor levels in patients with tuberculous pleurisy serve as markers of disease in non-endemic countries, similarly to ADA levels

COVID-19 pandemic and the global perspective of Turkish Thoracic Society

It has been more than 3 months now since the first case of COVID-19 was reported in Turkey. Globally, the number of confirmed cases and deaths reached 9,653,048 and 491,128 respectively, as reported by 216 countries by June 27, 2020. Turkey had 1,396 new cases, 194,511 total cases, and 5,065 deaths by the same date. From the first case until today, the Turkish Thoracic Society (TTS) has been very proactive in educating doctors, increasing public awareness, undertaking academic studies, and assisting with public health policies. In the present report, social, academic, and management perspectives of the pandemic are presented under appropriate subtitles. During this critical public health crisis, TTS has once again demonstrated its readiness and constructive stance by supporting public health, healthcare workers, and the environment. This review summarizes the perspective of TTS on each aspect of the COVID-19 pandemic and casts light on its contributions