Wireless Heterogeneous Networks and Next Generation Internet

The recent advances in wireless access technologies as well as the increasing number of mobile applications have made Wireless Internet a reality. A wide variety of bandwidth demanding services including high speed data delivery and multimedia communication have been materialized through the convergence of the next generation Internet and heterogeneous wireless networks. However, providing even higher bandwidth and richer applications necessitates a fundamental understanding of wireless Internet architecture and the interactions between heterogeneous users. Consequently, fundamental advances in many concepts of the wireless Internet are required for the ultimate goal of communication anytime anywhere. This special issue of the ACM Mobile Networks and Applications Journal is dedicated to the recent advances in the area of Wireless Internet. We accepted 10 papers out of 59 submissions from all over the world with a 17% acceptance rate. Papers describing management schemes, protocols, models, evaluation methods, and experimental studies of Wireless Internet are included in this special issue to provide a broad view of recent advances in this field

ANTENNA FOR WIRELESS UNDERGROUND COMMUNICATION

Systems and methods are disclosed for an underground antenna structure for radiating through a dissipative medium, the antenna structure. The antenna structure includes a dielectric substrate, a feeding structure disposed on the substrate, and one or more electrical conductors. The one or more electrical conductors are disposed on the substrate, oriented, and buried within the dissipative medium. The electrical conductors are also adapted to radiate signals at a frequency in half-space adjacent to the dissipative medium. The adaptation includes a beamwidth state for one or more of the electrical conductors based at least in part on the relative permittivity of the dissipative medium

'Behind Enemy Lines' Menzies, Evatt and Passports for Peking

This article focuses primarily on Australian government responses to the 1952 Peace Conference for Asia and the Pacific Regions. Because the conference was to be held in Peking, it was the subject of immense controversy: Chinese communists were fighting Australian soldiers in Korea and Australian peace activists, most communist or 'fellow travellers', sought to travel behind the 'bamboo curtain'. In this context, the Menzies government's policies on passports were sharply silhouetted. Although this conference has been overlooked in the literature, we can infer from the trajectory of relevant Cold War historiography that Prime Minister Menzies would adopt restrictive, even draconian, policies. This article argues otherwise. It suggests that it was that consistent champion of civil liberties, former deputy prime minister, attorney-general and secretary of the General Assembly of the United Nations and now, in 1952, Leader of the Opposition, Dr Evatt, who favoured more repressive action towards prospective delegates. In contrast, Menzies and his Cabinet were more lenient and shifted towards a harsher policy belatedly and reluctantly. This episode, therefore, challenges some comfortable assumptions about how the early Cold War was fought in Australia

Applications of Cognitive Radio Networks

The term cognitive radio (CR), originally coined in the late 1990s, envisaged a radio that is aware of its operational environment so that it can dynamically and autonomously adjust its radio-operating parameters to accordingly adapt to the different situations. Cognition is achieved through the so-called cognitive cycle, consisting of the observation of the environment, the orientation and planning that leads to making appropriate decisions in accordance with specific operation goals, and finally, the execution of these decisions (e.g., access to the appropriate channel). Decisions can be reinforced by learning procedures based on the past observations and the corresponding results of prior actuations

Determination of some phenolic compounds in olive oil with liquid chromatography by enrichment with reversed phase liquid-liquid microextraction

16.04.2016 tarihine kadar kullanımı yazar tarafından kısıtlanmıştır.Bu çalışmada, zeytinyağında bulunan sekoiridoit yapıdaki oleuropein, benzoik asit yapıdaki gallik asit, sinnamik asit yapıdaki kafeik asit, ferulik asit, p-kumarik asit ve fenolik alkollerden hidroksitirozol ve tirozol biyofenolik bileşiklerinin yüksek performanslı sıvı kromatografisi (HPLC) ile belirlenmesi öncesinde, zenginleştirilmesi için ters faz dağılımlı sıvı-sıvı mikroekstraksiyon (RP-DLLME) metodu geliştirilmiştir. Bu metot, sıvı-sıvı ekstraksiyon yönteminin minyatürize edilmiş hali olan ve üçlü bileşen çözücü sistemine (sulu ortam/ekstraksiyon çözgeni/dağıtıcı çözgen) dayanan dağılımlı sıvı-sıvı mikroekstraksiyon (DLLME) metodunun çözgen polaritesinin değiştirilmiş (çevrilmiş) halidir. RP-DLLME metodu, fenolik bileşiklerin yağ fazından tüpün dibinde oluşan mikrolitre hacim seviyelerindeki berrak sulu faza geçerek kromatografik kolona doğrudan enjekte edilip zenginleştirilmelerine olanak sağlamaktadır. Ekstraksiyon verimine etki edebilen parametrelerden olan pH, seyreltici cinsi, zeytinyağı-seyreltici hacim oranı, zeytinyağı hacmi, dağıtıcı çözgenin cinsi, dağıtıcı çözgenin hacmi, ekstraksiyon çözgeni olan suyun hacmi, tuz etkisi, santrifüj zamanı ve santrifüj hızı ile ilgili uygun çalışma koşulları belirlenmiştir. Bu koşullar; sırasıyla ortamın pH'sı 7, yağı seyreltmek amacıyla ilave edilen seyreltici cinsi hekzan, 1:1 hacim oranına sahip zeytinyağı-seyreltici oranı, zeytinyağı örnek hacmi 1 mL, ekstraksiyon çözgeni olan suyun hacmi 50 µL, dağıtıcı çözgen olan etil asetatın hacmi 100 µL olarak bulunmuştur. Bu koşullarda, fenolik bileşikler için geri kazanımlar %72,3-118,5, zenginleştirme faktörleri 14,4-17,1 aralığında değişiklik göstermiştir. Önerilen zenginleştirme metodu sızma ve riviera zeytinyağı örneklerine de uygulanmış ve biyofenolik bileşikler ppb seviyelerinde yeterli kromatografik çözünürlükle tayin edilmiştir.In this study, a reversed phase dispersive liquid-liquid microextraction method (RP-DLLME) for the enrichment of natural biophenolic compounds of oleuropein, gallic acid, caffeic acid, ferulic acid, p-coumaric acid, hydroxytyrosol and tyrosol compunds in olive oil has been developed prior to their liquid chromatographic determinations. Ordinary (normal phase) DLLME is a miniaturized Liquid-liquid extraction and is based on a ternary component solvent system in which the extraction solvent and disperser solvent are rapidly injected into the aqueous sample by syringe. The RP-DLLME method overturns the solvent polarity in the ordinary DLLME and replaces the chlorinated toxic solvents with water. In this application of the RP-DLLME method to oil samples, the phenolic compounds are directly extracted into an aqueous micro-drop, which can be injected into a chromatograpy column without any further pretreatment. The parameters affecting extraction efficiency of the RP-DLLME method such as pH of water, type of diluter solvent, volume ratio between the olive oil sample and the diluter, volume of sample, type and volume of disperser solvent, volume of extraction solvent (water), salt effect, centrifugation time and centrifugation speed were investigated. Under the optimum extraction conditions (1.0 mL of sample volume, 1.0 mL of hexane as diluter solvent, 50 µL of water as extraction solvent, 100 µL of ethyl acetate as disperser solvent at pH:7) gave enrichment factor in the range of 14.4-17.1. Recoveries for the studied phenolic compounds were 72.3-118.5%. Proposed enrichment method was also applied to virgin olive oil and pure olive oil samples. Biophenolic compounds were detected at ppb levels with adequate chromatographic resolution

Correlation-based Cross-layer Communication in Wireless Sensor Networks

Wireless sensor networks (WSN) are event based systems that rely on the collective effort of densely deployed sensor nodes continuously observing a physical phenomenon. The spatio-temporal correlation between the sensor observations and the cross-layer design advantages are significant and unique to the design of WSN. Due to the high density in the network topology, sensor observations are highly correlated in the space domain. Furthermore, the nature of the energy-radiating physical phenomenon constitutes the temporal correlation between each consecutive observation of a sensor node. This unique characteristic of WSN can be exploited through a cross-layer design of communication functionalities to improve energy efficiency of the network. In this thesis, several key elements are investigated to capture and exploit the correlation in the WSN for the realization of advanced efficient communication protocols. A theoretical framework is developed to capture the spatial and temporal correlations in WSN and to enable the development of efficient communication protocols. Based on this framework, spatial Correlation-based Collaborative Medium Access Control (CC-MAC) protocol is described, which exploits the spatial correlation in the WSN in order to achieve efficient medium access. Furthermore, the cross-layer module (XLM), which melts common protocol layer functionalities into a cross-layer module for resource-constrained sensor nodes, is developed. The cross-layer analysis of error control in WSN is then presented to enable a comprehensive comparison of error control schemes for WSN. Finally, the cross-layer packet size optimization framework is described.Ph.D.Committee Chair: Ian F. Akyildiz; Committee Member: Douglas M. Blough; Committee Member: Mostafa Ammar; Committee Member: Raghupathy Sivakumar; Committee Member: Ye (Geoffrey) L

Comparison of the Profitability Performance of BIST Corporate Governance Index Companies in Turkey

Corporate governance is the system of rules, practices and processes by which a company is directed and controlled. Through appropriate implementation of the principles of corporate governance a company can enhance its financial performance, improve its competitiveness, appreciate its credibility and reputation and increase relations with key stakeholders. Borsa Istanbul (BIST) Corporate Governance Index (XKURY) is composed of listed companies who accomplished a certain level of Corporate Governance Principles. This study investigates the links between profitability performance and good corporate governance practices. It aims to test empirically that if there is a significant difference between the profitability performance of two group of non-financial companies listed in Borsa Istanbul 100 index. Level of performance is assessed by determining the net profit margin, gross profit  margin, return on asset, return on equity, return on sales and return on invested capital for the sample of companies. Data are taken from annual reports of the companies in the 2015 and based on a sample of 25 XKURY companies 47 non-XKURY companies listed in Borsa Istanbul 100 index. As a result, the companies who comply better with the corporate governance principles are found to have better profitability performance against the others. It is observed that good corporate governance practices positively influence the efficiency and financial results of business operations. Keywords: Corporate Governance Index, Borsa Istanbul, Corporate Profitability, Corporate Governance Practices

A Multicriterion Decision Support Methodology For Audit Opinions: The Case Of Audit Reports Of Distressed Firms In Turkey

The audit report represents the most important part of the audit process and it is the sole communication medium between the auditor and the users of the financial statements. After accounting scandals, auditors’ responsibility for assessing the appropriateness of audit opinions has become the subject of much debate in the auditing profession and considerable research by academics. This increased attention is due to the fact that auditors appear to be reluctant to disclose audit opinions other than unqualified. Indeed, many companies in the year prior to bankruptcy receive an audit report in which going concern uncertainty is not disclosed. The research of this paper is designed to examine the relationship between the type of audit reports and firm failure. Logistic regression analysis is applied to test the model of audit opinion decision with a sample of financially distressed firms operating in manufacturing sector in Istanbul Stock Exchange (ISE) between the period of 1998-2006. The results reveal that the audit opinions of distressed firms indicate the auditors fail to issue appropriate audit opinions one year prior to failure