Secure Full-Duplex Small-Cell Networks in a Spectrum Sharing Environment

In this paper, we propose three relay selection schemes for full-duplex heterogeneous networks in the presence of multiple cognitive radio eavesdroppers. In this setup, the cognitive small-cell nodes (secondary network) can share the spectrum licensed to the macro-cell system (primary network) on the condition that the quality-of-service of the primary network is always satisfied subjected to its outage probability constraint. The messages are delivered from one small-cell base station to the destination with the help of full-duplex small-cell base stations, which act as relay nodes. Based on the availability of the network’s channel state information at the secondary information source, three different selection criteria for full-duplex relays, namely: 1) partial relay selection; 2) optimal relay selection; and 3) minimal self-interference relay selection, are proposed. We derive the exact closed-form and asymptotic expressions of the secrecy outage probability for the three criteria under the attack of non-colluding/colluding eavesdroppers. We demonstrate that the optimal relay selection scheme outperforms the partial relay selection and minimal self-interference relay selection schemes at the expense of acquiring full channel state information knowledge. In addition, increasing the number of the full-duplex small-cell base stations can improve the security performance. At the illegitimate side, deploying colluding eavesdroppers and increasing the number of eavesdroppers put the confidential information at a greater risk. Besides, the transmit power and the desire outage probability of the primary network have great influences on the secrecy outage probability of the secondary network. 

Integrated Optimal Power Flow for Distribution Networks in Local and Urban Scales

This paper develops an integrated optimal power flow (OPF) tool for distribution networks in two spatial scales. In the local scale, the distribution network, the natural gas network, and the heat system are coordinated as a microgrid. In the urban scale, the impact of natural gas network is considered as constraints for the distribution network operation. The proposed approach incorporates unbalance three-phase electrical systems, natural gas systems, and combined cooling, heating, and power systems. The interactions among the above three energy systems are described by energy hub model combined with components capacity constraints. In order to efficiently accommodate the nonlinear constraint optimization problem, particle swarm optimization algorithm is employed to set the control variables in the OPF problem. Numerical studies indicate that by using the OPF method, the distribution network can be economically operated. Also, the tie-line power can be effectively managed.

The use of binary polymeric networks in stabilising polyethylene oxide solid dispersions

The objective of this study was to determine if a high Tg polymer (Eudragit® S100) could be used to stabilize amorphous domains of polyethylene oxide (PEO) and hence improve the stability of binary polymer systems containing celecoxib (CX). We propose a novel method of stabilizing the amorphous PEO solid dispersion through inclusion of a miscible, high Tg polymer, namely, that can form strong inter-polymer interactions. The effects of inter-polymer interactions and miscibility between PEO and Eudragit S100 are considered. Polymer blends were first manufactured via hot-melt extrusion at different PEO/S100 ratios (70/30, 50/50, and 30/70 wt/wt). Differential scanning calorimetry and dynamic mechanical thermal analysis data suggested a good miscibility between PEO and S100 polymer blends, particularly at the 50/50 ratio. To further evaluate the system, CX/PEO/S100 ternary mixtures were extruded. Immediately after hot-melt extrusion, a single Tg that increased with increasing S100 content (anti-plasticization) was observed in all ternary systems. The absence of powder X-ray diffractometry crystalline Bragg’s peaks also suggested amorphization of CX. Upon storage (40°C/75% relative humidity), the formulation containing PEO/S100 at a ratio of 50:50 was shown to be most stable. Fourier transform infrared studies confirmed the presence of hydrogen bonding between Eudragit S100 and PEO suggesting this was the principle reason for stabilization of the amorphous CX/PEO solid dispersion system.

Clustering-based Query Routing in Cooperative Semi-structured Peer to Peer Networks

We consider the problem of resource selection in clustered Peer-to-Peer Information Retrieval (P2P IR) networks with cooperative peers. The clustered P2P IR framework presents a significant departure from general P2P IR architectures by employing clustering to ensure content coherence between resources at the resource selection layer, without disturbing document allocation. We propose that such a property could be leveraged in resource selection by adapting well-studied and popular inverted lists for centralized document retrieval. Accordingly, we propose the Inverted PeerCluster Index (IPI), an approach that adapts the inverted lists, in a straightforward manner, for resource selection in clustered P2P IR. IPI also encompasses a strikingly simple peer-specific scoring mechanism that exploits the said index for resource selection. Through an extensive empirical analysis on P2P IR testbeds, we establish that IPI competes well with the sophisticated state-of-the-art methods in virtually every parameter of interest for the resource selection task, in the context of clustered P2P IR.

The role of the National Audit Office in Private Finance Initiative endurance

The Private Finance Initiative (PFI) has become one of the UK’s most contentious public policies. Despite New Labour’s advocacy of PFI as a means of achieving better value for money, criticisms of PFI have centred on key issues such as a lack of cost effectiveness, exaggerated pricing of risk transfers, excessive private sector profits, inflexibility and cumbersome administrative arrangements. Nevertheless, PFI has persisted as a key
infrastructure procurement method in the UK and has been supported as such by successive governments, as well as influencing policy in the Republic of Ireland and other European Nations. This paper explores this paradoxical outcome in relation to the role played in the UK by the National Audit Office (NAO). Under pressure to justify its support for PFI, the Blair government sought support for its policies by encouraging the NAO to investigate issues relating to PFI as well as specific PFI projects. It would have been expected that in fulfilling its role as independent auditor, the NAO would have examined whether PFI projects could have been delivered more efficiently, effectively or economically through other means. Yet, in line with earlier research, we find evidence that the NAO failed to comprehensively assess
key issues such as the value for money of PFI projects, and in so doing effectively acted as a legitimator of PFI policy. Using concepts relating to legitimacy theory and the idea of framing, our paper looks into 67 NAO private finance reports published between 1997 and 2011, with the goal of identifying the preferences, values and ideology underpinning the
NAO’s view on PFI during this period. Our analysis suggests that the NAO sought to legitimise existing PFI practices via a selective framing of problems and questions. Utilising a longitudinal approach, our analysis further suggests that this patterns of selective framing persisted over an extended time period during which fundamental parameters of the policy (such as contract length, to name one of the most important issues) were rarely addressed.
Overall the NAO’ supportive stance toward PFI seems to have relied on 1) a focused on positive aspects of PFI, such as on time delivery or lessons learned, and 2) positive comments on aspects of PFI that were criticised elsewhere, such as the lack of flexibility of underlying contractual arrangements. Our paper highlights the possibility that, rather than providing for a critical assessment of existing policies, national auditing bodies can
contribute to the creation of legitimatory environments. In terms of accounting research we would suggests that the objectivity and independence of accounting watchdogs should not be taken for granted, and that instead a critical investigation of the biases which can characterise these bodies can contribute to a deeper understanding of the nature of lobbying networks in the modern state.