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Adding relay stations (RS) between the base station (BS) and the mobile stations (MS) in a cellular system can extend network coverage, overcome multi-path fading and increase the capacity of the system. This thesis considers the radio resource allocation scheme in relay based cellular networks to ensure high-speed and reliable communication. The goal of this research is to investigate user fairness, system throughput and power consumption in wireless relay networks through considering how best to manage the radio resource. This thesis proposes a two-hop proportional fairness (THPF) scheduling scheme fair allocation, which is considered both in the first time subslot between direct link users and relay stations, and the second time subslot among relay link users. A load based relay selection algorithm is also proposed for a fair resource allocation. The transmission mode (direct transmission mode or relay transmission mode) of each user will be adjusted based on the load of the transmission node. Power allocation is very important for resource efficiency and system performance improvement and this thesis proposes a two-hop power allocation algorithm for energy efficiency, which adjusts the transmission power of the BS and RSs to make the data rate on the two hop links of one RS match each other. The power allocation problem of multiple cells with inter-cell interference is studied. A new multi-cell power allocation scheme is proposed from non-cooperative game theory; this coordinates the inter-cell interference and operates in a distributed manner. The utility function can be designed for throughput improvement and user fairness respectively. Finally, the proposed algorithms in this thesis are combined, and the system performance is evaluated. The joint radio resource allocation algorithm can achieve a very good tradeoff between throughput and user fairness, and also can significantly improve energy efficiency.

Abstract: Lateral–torsional buckling is a stability-related failure mode of unbraced or insufficiently braced flexural members. In recent years, several concerns have been raised regarding the adequacy of the Canadian steel design standard, CSA S16-14, in characterising the lateral–torsional buckling resistance of members made up of three plates welded together into an I-shaped section, as is commonly done for deep girders. The large heat input from welding results in residual stress distributions that may cause these welded sections to be more susceptible to lateral–torsional buckling than their rolled counterparts, particularly in the inelastic region. However, the paucity of up-to-date physical test data for modern welded girders considerably limits the potential for an adequate evaluation of the current design provisions. To improve the understanding of lateral–torsional buckling behaviour, an experimental programme was developed, consisting of 11 welded girders with unbraced spans of 9.75 m (32 ft). Test specimens were selected and designed by considering various parameters that may influence lateral–torsional buckling resistance. Preliminary finite element simulations were conducted to anticipate displacements and rotations of the test specimens, which were used to inform the design of an experimental test set-up capable of accommodating the full range of expected movement. The observed moment resistances and stability response from seven tests were analysed, and the effects of initial geometric imperfections, residual stresses, and geometric parameters were considered. Test results were compared against predictions from CSA S16-14, with adjustments applied to account for load height effects from the gravity load mechanism, and the adequacy of the Canadian provisions for lateral–torsional buckling resistance was evaluated.

Online group buying, as a new form of e-commerce, is one of the most innovative e-commerce business models. This model offers great opportunities for e-marketers, but also brings new challenges. In the last four years, more than 5000 online group buying vendors in China have gone out of business. Existing literature suggests that online group buying is distinctive from online shopping, and consumers are motivated to use online group buying to enjoy different benefits. As little research has been conducted on understanding consumers in this context, group buying websites have few guidelines to follow to improve competitiveness. This thesis addresses this challenge by exploring the hierarchical motivations underlying consumers’ online group buying behaviour and the development of consumer typologies from a new perspective. Specifically, utilising a Uses and Gratifications (U&G) approach and Means-End Chain (MEC) theory perspective, this study aims not only to explore the content of online group buyers’ motivations, but also uncover the inter-relationships among these motivations. Moreover, it aims to introduce a new method to segment consumer, based on benefit-level motivations, which can provide more accurate consumer typologies. To reach these objectives the laddering interview technique was used to collect data from 58 online group buyers in China. A context-specific hierarchical motive model was developed, based on the 35 motivations identified, which not only indicated consumer value/goal fulfilment paths, but also illustrated the relative importance of different paths. Moreover, three typologies of group buyers with distinct value/goal fulfilment paths were identified, fundamentally different from existing shopper typologies in the e-commerce context. As a timely topic using a novel approach to explore consumer online group buying motivations, this study adds to the online group buying literature, introduces a new segmentation approach that overcomes the limitations of the traditional rating-scale based segmentation, and demonstrates theories and techniques derived from other disciplines that can be effectively applied to information systems and e-commerce research. This study will also help practitioners involved in online group buying businesses to better plan and design strategies to attract and retain current and potential consumers.

Due to the increased adoption of the Internet over the last decade, business-to-consumer (B2C) e-commerce has become a popular medium for consumers to purchase products or services. However, despite a growth in e-commerce, it is difficult to succeed in online businesses because customers can easily switch between competitors and it is difficult to gain consumers' trust online. Trust is a complex and multifaceted issue that must be addressed from multiple angles. Previous research on trust has attempted to understand consumers' attitudes, intentions, and behaviours that are related to trust in online shopping. However, few studies have provided a comprehensive understanding of the multi-dimensional nature of the trust construct such as the impacts of different trust dimensions on e-loyalty, inter-relationships among trust dimensions, and antecedents of different trust dimensions. The objective of this research is to fill the gaps by investigating the factors that affect different types of trust, the relationships among different types of trust and the importance of the trust issues in forming e-loyalty in the online environment. Led by the literature, a research model was proposed and hypotheses were developed to explore the answers to the research questions. Data was collected through a web-based survey in Chinese markets and Structural Equation Modelling (SEM) with Partial Least Squares (PLS) was used to analyse the data. Empirical results showed that all three dimensions of trust had impacts on e-loyalty. Dispositional trust had an impact on institutional trust, and institutional trust had an impact on interpersonal trust. Among the factors that influence interpersonal trust, store reputation and information quality not only had significantly impacts on interpersonal trust, but also mediated the relationships between other antecedents and interpersonal trust. This research contributes to the body of knowledge on trust by exploring the nature of trust with a multi-dimensional scale. Another theoretical contribution is the provision of a comprehensive understanding of the trust antecedents in e-commerce. Furthermore, this research benefits the companies doing e-businesses by allowing them to better understand how to improve consumers' trust in the online environment and thus to retain and attract more loyal customers and succeed in online businesses.