Car-Park Management using Wireless Sensor Networks

A complete wireless sensor network solution for car-park management is presented in this paper. The system architecture and design are first detailed, followed by a description of the current working implementation, which is based on our DSYS25z sensing nodes. Results of a series of real experimental tests regarding connectivity, sensing and network performance are then discussed. The analysis of link characteristics in the car park scenario shows unexpected reliability patterns which have a strong influence on MAC and routing protocol design. Two unexpected link reliability patterns are identified and documented. First, the presence of the objects (cars) being sensed can cause significant interference and degradation in communication performance. Second, link quality has a high temporal correlation but a low spatial correlation. From these observations we conclude that a) the construction and maintenance of a fixed topology is not useful and b) spatial rather than temporal message replicates can improve transport reliability

Applications of ultrasound for the functional modification of proteins and submicron emulsion fabrication

This thesis aims to advance the understanding of ultrasonic processing for the alteration of food microstructures. It considers the impact of ultrasonic processing upon protein structure and for emulsification. It was shown that ultrasound treatment of proteins reduced the hydrodynamic volume of protein aggregates by ultrasonic cavitations. Insufficient acoustic energy was provided to achieve proteolysis. Emulsions prepared with ultrasound treated milk protein isolate, pea protein isolate and bovine gelatin yielded smaller, stable emulsion droplets in comparison to their untreated counterparts. This behaviour is ascribed to more rapid adsorption of protein at the oil-water interface and improved interfacial packing, due to reduction in protein aggregate size. The droplet size of emulsions with sufficient emulsifier (> 0.5 wt. %) emulsion droplet size can be predicted from a mathematical relation between emulsion droplet size (d3,2) and energy density (Ev), an inverse power law. Droplet size predictions were unattainable at low emulsifier concentrations (≤ 0.5 wt. %) due to re-coalescence behaviour attributed to insufficiency of emulsifier and droplet collisions within the acoustic field. Continuous processing yields more efficient utilisation of acoustic energy in comparison to batch configurations due to the intense transmission of acoustic energy within the smaller processing volumes

Influence of Atmospheric Turbulence on Optical Communications using Orbital Angular Momentum for Encoding

We describe an experimental implementation of a free-space 11-dimensional communication system using orbital angular momentum (OAM) modes. This system has a maximum measured OAM channel capacity of 2.12 bits/photon. The effects of Kolmogorov thin-phase turbulence on the OAM channel capacity are quantified. We find that increasing the turbulence leads to a degradation of the channel capacity. We are able to mitigate the effects of turbulence by increasing the spacing between detected OAM modes. This study has implications for high-dimensional quantum key distribution (QKD) systems. We describe the sort of QKD system that could be built using our current technology.Comment: 6 pages, 5 figure

Towards Planetary Urban Criminology

Urbanisation is the dominant global social process of the current century and criminology is an intrinsically urban discipline. However, criminology has become dominated by the analysis of subsets of areas within a subset of rather homogeneous cities of the Global North. As the discipline has evolved and refracted under the impetus of theoretical, methodological and data advance, it has lost much of its urban vitality, lacking critical self-awareness of its fundamental nature. We argue for a new, or renewed, approach to criminology that begins from the perspective of the city as an open system. We assess the consequences of a criminology that fails to take proper account of the city as a multi-scalar open system. This is without doubt a considerable challenge, but the time is propitious; in the era of Big Data, with a rapidly expanding range of methodologies at its disposal, there exists the possibility for a revivified criminology that remains faithful to its roots. Our proffered approach opens the way to investigating crime through an urban prism for any city in the world – to a planetary urban criminology

A Generic Algorithm for Mid-call Audio Codec Switching

We present and evaluate an algorithm that performs in-call selection of the most appropriate audio codec given prevailing conditions on the network path between the endpoints of a voice call. We have studied the behaviour of different codecs under varying network conditions, in doing so deriving the impairment factors for non-ITU-T codecs so that the E-model can be used to assess voice call quality for them. Moreover, we have studied the drawbacks of codec switching from the end user perception point of view; our switching algorithm seeks to minimise this impact. We have tested our algorithm on different packages that contain a selection of the most commonly used codecs: G.711, SILK, ILBC, GSM and SPEEX. Our results show that in many typical network scenarios, our switching codecs mid-call algorithm results in better Quality of Experience (QoE) than would have been achieved had the initial codec been used throughout the call