Thesis (M.S.), Human Environmental Sciences--University of Central Oklahoma, 2010. / Includes bibliographical references (leaves 31-34).

Thesis (Ph. D.)--University of Maryland, College Park, 2005. / Includes bibliographical references (leaves 101-105).

Thesis (doctoral) - Johann Wolfgang Goethe-Universität, Frankfurt am Main, 2006. / Includes bibliographical references (p. 225-234).

Please note: creative writing theses are permanently embargoed in OpenBU. No public access is forecasted for these. To request private access, please click on the locked Download file link and fill out the appropriate web form. / No abstract required. / 2031-01-01

In this thesis, spectrum sensing techniques are investigated for cognitive radio (CR) networks in order to improve the sensing and transmission performance of secondary networks. Specifically, the detailed exploration comprises of three areas, including single-node spectrum sensing based on eigenvalue-based detection, cooperative spectrum sensing under random secondary networks and full-duplex (FD) spectrum sensing and sharing techniques. In the first technical chapter of this thesis, eigenvalue-based spectrum sensing techniques, including maximum eigenvalue detection (MED), maximum minimum eigenvalue (MME) detection, energy with minimum eigenvalue (EME) detection and the generalized likelihood ratio test (GLRT) eigenvalue detector, are investigated in terms of total error rates and achievable throughput. Firstly, in order to consider the benefits of primary users (PUs) and secondary users (SUs) simultaneously, the optimal decision thresholds are investigated to minimize the total error rate, i.e. the summation of missed detection and false alarm rate. Secondly, the sensing-throughput trade-off is studied based on the GLRT detector and the optimal sensing time is obtained for maximizing the achievable throughput of secondary communications when the target probability of detection is achieved. In the second technical chapter, the centralized GLRT-based cooperative sensing technique is evaluated by utilizing a homogeneous Poisson point process (PPP). Firstly, since collaborating all the available SUs does not always achieve the best sensing performance under a random secondary network, the optimal number of cooperating SUs is investigated to minimize the total error rate of the final decision. Secondly, the achievable ergodic capacity and throughput of SUs are studied and the technique of determining an appropriate number of cooperating SUs is proposed to optimize the secondary transmission performance based on a target total error rate requirement. In the last technical chapter, FD spectrum sensing (FDSS) and sensing-based spectrum sharing (FD-SBSS) are investigated. There exists a threshold pair, not a single threshold, due to the self-interference caused by the simultaneous sensing and transmission. Firstly, by utilizing the derived expressions of false alarm and detection rates, the optimal decision threshold pair is obtained to minimize total error rate for the FDSS scheme. Secondly, in order to further improve the secondary transmission performance, the FD-SBSS scheme is proposed and the collision and spectrum waste probabilities are studied. Furthermore, different antenna partitioning methods are proposed to maximize the achievable throughput of SUs under both FDSS and FD-SBSS schemes.

abstract: Traditional wireless communication systems operate in duplexed modes i.e. using time division duplexing or frequency division duplexing. These methods can respectively emulate full duplex mode operation or realize full duplex mode operation with decreased spectral efficiency. This thesis presents a novel method of achieving full duplex operation by actively cancelling out the transmitted signal in pseudo-real time. With appropriate hardware, the algorithms and techniques used in this work can be implemented in real time without any knowledge of the channel or any training sequence. Convergence times of down to 1 ms can be achieved which is adequate for the coherence bandwidths associated with an indoor environment. By utilizing adaptive cancellation, additional overhead for re-calibrating the system in other open-loop methods is not needed. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016

abstract: The demand for the higher data rate in the wireless telecommunication is increasing rapidly. Providing higher data rate in cellular telecommunication systems is limited because of the limited physical resources such as telecommunication frequency channels. Besides, interference with the other users and self-interference signal in the receiver are the other challenges in increasing the bandwidth of the wireless telecommunication system. Full duplex wireless communication transmits and receives at the same time and the same frequency which was assumed impossible in the conventional wireless communication systems. Full duplex wireless communication, compared to the conventional wireless communication, doubles the channel efficiency and bandwidth. In addition, full duplex wireless communication system simplifies the reusing of the radio resources in small cells to eliminate the backhaul problem and simplifies the management of the spectrum. Finally, the full duplex telecommunication system reduces the costs of future wireless communication systems. The main challenge in the full duplex wireless is the self-interference signal at the receiver which is very large compared to the receiver noise floor and it degrades the receiver performance significantly. In this dissertation, different techniques for the antenna interface and self-interference cancellation are proposed for the wireless full duplex transceiver. These techniques are designed and implemented on CMOS technology. The measurement results show that the full duplex wireless is possible for the short range and cellular wireless communication systems. / Dissertation/Thesis / Doctoral Dissertation Engineering 2017

The Full IFRS caters to the needs of shareholding corporations and their investors, which also led to incurring high cost especially for SMEs due to the requirements of financial reporting constructed for public companies as it is very complex and requires a high amount of disclosure (Fearnley and Hines, 2007, Haller and Eirle, 2008, Eierle and Haller, 2009). Hence, for the purpose of reducing essentially the reporting burdens facing SMEs, IASB in 2009 issued IFRS for SMEs. This study aims to investigate the relevance and suitability of IFRS for SMEs in Jordan. It will also analyse the current problems faced by Jordanian SMEs in the light of applying the current IFRSs, furthermore, the expected benefits from applying IFRS for SMEs, will be addressed. A total of 10 interviews with external auditors were conducted to test the ground and determine the relevant topics within IFRS for SMEs in Jordanian SMEs context. In addition to that, a total of 605 questionnaires were distributed to external auditors and financial managers of SMEs who prepare financial statements based on full IFRS. The overall outcomes reveal that managers; banks and creditors; public authorities; and analysts were the most frequent and important SMEs’ financial information users while both employees and shareholders were found as rare users of financial statements presented by SMEs. Furthermore, the current applied standards are substantially characterised to embrace many problems such as; the complexity of measurements and recognitions; high disclosures requirements; making inappropriate decisions and other issues pertaining to preparing financial reports. On the other hand, although the respondents especially the auditors group were evidently worried about several potential obstacles that may impede the effective application of IFRS for SMEs, both groups of users were obviously optimistic about the capability of IFRS for SMEs to mitigate the aforementioned problems and to enhance the accounting practice in terms of preparing and using the financial information. With respect to topics from full IFRS that have been omitted in IFRS for SMEs, all respondents agreed to exclude these topics from the IFRS for SMEs’ content due to the irrelevance of these topics to SMEs’ context. Likewise, the overall participants approved on the most proposals under IFRS for SMEs compared to those based on full IFRS except the suggestion associated with measuring some kind of assets, for instance; investment property; intangible; property; plant and equipment, which were rejected only by the group of managers while several proposals regarding expensing some kind of costs instead of capitalise them as well as lease matters were neither agreed nor disagreed by respondents. Finally the majority of responses show that both groups were willing to adopt IFRS for SMEs. The key contribution provided evidences as to whether the adoption of IFRS for SMEs would be a necessary undertaking. Thus, a recommendation were mainly made to the standard-setters on the basis of preparers’ perceptions of the importance of applying such financial standards.

To achieve better scalability, a fully replicated, distributed, main-memory database is divided into subparts, called segments. Segments may have individual degrees of redundancy and other properties that can be used for replication control. Segmentation is examined for the opportunity of decreasing replication effort, lower memory requirements and decrease node recovery times. Typical usage scenarios are distributed databases with many nodes where only a small number of the nodes share information. We present a framework for virtual full replication that implements segments with scheduled replication of updates between sharing nodes. Selective replication control needs information about the application semantics that is specified using segment properties, which includes consistency classes and other properties. We define a syntax for specifying the application semantics and segment properties for the segmented database. In particular, properties of segments that are subject to hard real-time constraints must be specified. We also analyze the potential improvements for such an architecture.

Non-destructive testing (NDT) is the process of non-invasive material examination. Within this field, ultrasonic inspection is one method of examination used to detect flaws in structural and functional industrial components, to assess their structural integrity and fitness for service. Conventional NDT ultrasonic array techniques transmit on multiple elements in parallel, according to a focal law, which facilitates beam steering, focussing and scanning within the test component. Received signals are then 'stacked' to generate images of the test component. With the advent of affordable high speed computing, novel data acquisition techniques based on sequential transmission are now able to be developed, which allow images to be generated using advanced signal processing and image reconstruction algorithms. One such data acquisition technique known as Full Matrix Capture (FMC), has received considerable research attention in recent years, largely because it allows fully focused images of test components to be generated. This project provides an improved understanding of the FMC technique and associated signal processing algorithms. It achieves this through the development of novel inspection techniques and signal processing algorithms. Collectively algorithms developed within this work were termed Sequential Phased Array (SPA). Initially comparisons were made between conventional ultrasonic techniques and the SPA algorithms in terms of image quality and speed of inspection. A novel approach was then suggested to facilitate inspection through dual-layered media, separated by a refractive interface using the SPA algorithms. The use of sparse arrays to enhance the speed of inspection using the SPA algorithms was also investigated, and the trade-off between speed of inspection against image degradation was addressed. Finally a novel approach to calibration of a FMC based system was developed, in order to provide uniform image sensitivity during inspection.