A novel maximal-length sequence synchronisation network

Spread Spectrum has become a popular digital modulation scheme in recent years. The advantages the scheme offers, at the expense of bandwidth, make it attractive in a multitude of commercial applications. The most common method, and the one of interest in this thesis, of generating Spread Spectrum is multiplying the data waveform by a wideband, digitally generated waveform. This is referred to as Direct Sequence Spread Spectrum. The characteristics of Spread Spectrum systems are determined by the spreading waveform. A common group of spreading waveforms, and the ones dealt with in this text, are the maximal-length sequences. These are a class of pseudorandom waveforms. Their properties include a two valued autocorrelation function with its maximum value at no code-phase offset. This allows for multiple access to a single resource and the suppression of multi-path interference as adjacent codes have little effect on each other. This same property requires that the receiver must accurately align its replica of the spreading waveform to the transmitted waveform in order to despread the received waveform and demodulate the data. Common methods of synchronisation use a two pronged solution. Firstly the correct code phase is determined. This is referred to as code acquisition. Secondly the clocking frequency of the received waveform must be resolved in order to precisely align the two sequences. This is referred to as code tracking. Receivers therefore tend to be complex and expensive. This thesis involved the investigation of two pseudo-noise synchronisation networks proposed by J .G. van de Groenendaal. These networks offered both code acquisition and tracking in a single robust loop. The investigation, done in co-operation with J..G. van de Groenendaal, persued two avenues. Firstly the loops were simulated. This method allows for the easy alteration of system parameters. Valuable insight into the loop dynamics can thus be gained. Secondly the loops were built on the bench. This allows for the practical confirmation of the results of the simulation. Both synchronisation loops were based on variations of the maximal likelihood phase detector. This phase detector is formed by taking the product of the first derivative with respect to time of the receiver's replica of the transmitted waveform and the received waveform. The initial investigation involved calculating the phase information generated by this phase discriminator for a variety of code-phase and frequency offsets. It was found that there were two stable points in the baseband Spread Spectrum search grid, a grid where a cell consists of a certain code-phase and frequency offset. These stable points existed at no frequency offset, which means that the loops should track the input frequency, and a one or no code-phase offset, which means that the loops should acquire either code-phase. A simple model where the novel synchronisation loop's conditions are represented by a 'ball' resting on the baseband Spread Spectrum search grid as expressed in terms of the integrated phase output of the maximal likelihood phase discriminator was developed. In this model the 'ball' will roll around the surface until one of the two stable points is entered. This describes quite accurately the paths the novel synchronisation loop does in fact take through the baseband Spread Spectrum search grid. The first loop is based directly on the maximal likelihood phase detector. The differentiator is thus in the feedback path of the loop. This results in the loop being unstable and parameter sensitive. Moving the differentiator into the input path, as in the second loop, resulted in a more stable loop. This loop therefore offered a complete, simple synchronisation solution. The novel synchronisation loop with the differentiator in the input path was found to operate at signal-to- noise ratios of -2 dB. Improvement of this signal-to-noise ratio does not offer any advantages in a Spread Spectrum environment as the loop needs to work in a coherent system where the radio frequency carrier must be resolved before the receiver's pseudo-noise sequence can be synchronised. A radio frequency carrier cannot be easily resolved at signal-to-noise ratios lower than O dB. The loop was further adapted to operate in the data environment. Under conditions of data modulation the received waveform is randomly inverted by the data. This results in the loop being driven out of lock. The phase discriminator's slope, having locked on a certain polarity, cannot track an input of the opposite polarity. The loop was adapted by including detection circuitry that would monitor the state of the receiver with respect to the incoming data waveform and alter the polarity of the of the discriminator's slope where necessary. During the prototyping of the loop on the bench certain implementations were investigated. These included the signed edge detector, a wideband low noise implementation of a square wave differentiator, and the synchronous oscillator, a form of injection locked oscillator. The loop was shown to achieve synchronisation. The novel synchronisation loop with the differentiator in the input path is thus capable of synchronising two maximal-length sequences in both code-phase and frequency

Understanding and valuing the economic, social and environmental components of System Harmonisation

The aim of the Products and Markets component of the System Harmonisation project is to value the economic and environmental outcomes from an irrigation scheme that is operated by and in the interests of society. In this conceptual note the thinking underlying this component of the project are outlined. The aim of this note is to provide elements for debated. The nature and requirements of System Harmonisation demands that a 'systems approach' be taken throughout the project. What becomes important within this approach is how the different elements within a system are isolated and yet linked with one another. In many instances the extent and nature of irrigation systems are defined by the relevant Regional Irrigation Business Partnership (RIBP) under investigation. It is recognised that society has multiple uses for the water (agriculture, industry, households, recreation and the environment) as well as non-use (intrinsic) values for which it derives benefits from and incurs costs in distributing the water in any select manner. Further, it is assumed that the irrigation schemes are run for the benefit of society as a whole. Thus, there is a necessity to evaluate both the private and public costs and benefits associated with irrigation schemes. In order to identify what society values from an irrigation scheme, it is argued that a social matrix approach is needed. This analysis allows for a clustering of the issues people feel is important to them regarding the use of an irrigation scheme. Such an analysis will allow identification of the perceived most and least beneficial activities connected to water allocation, economic modelling of the most productive activities, evaluation of externalities and Cost Benefit Analysis. The net economic benefits that arise from irrigation need to be evaluated. The sectors where benefits are derived can be segregated into agriculture, households, the environment, recreation and industrial uses. The largest of these, by pure scale of the use of water, is agriculture. A gross margins approach is used to evaluate the returns for water in the agricultural sector. In the industrial and household sectors, a simple evaluation approach is used where the quantity of water demanded is multiplied by the price paid in each sector. Non-market valuation techniques are used to evaluate the recreational and environmental uses of water. The difficulty that arises in this analysis is how to evaluate the performance of irrigation schemes, where the outcomes are multifaceted. A 'meta' model approach is suggested in which the different elements from the project are brought together and assessed using a technique derived from the theory surrounding production possibility frontiers. This technique can be used to hypothesise a value for the ecosystem services derived from an irrigation scheme. The performance of an irrigation scheme is evaluated in terms of the suggestions raised to change it. Cost Effective Analysis is to be utilised to evaluate this performance. Then two issues need to be addressed. First, it is necessary to converse with those from other components, particularly those involved in the hydrological programs, to determine the nature of the schemes to be investigated. Second, it is necessary to implement the approach in each of the RIBPs. This work needs to commence with the evaluation of the social values in each region

Assessing social acceptability of management options for harmonising irrigation with environmental concerns: A pilot study from the Murrumbidgee Valley, Australia

The flows in regulated rivers are strongly dependent on water demand by downstream water users. In irrigated catchments the river flow regimes are deliberately distorted to cater for crop demand, with significant deleterious ecological impacts. A number of opportunities exist to manipulate irrigation demand and supply to provide more natural seasonality of flows and optimise the social, environmental and economic outcomes from water use in a catchment. Possible options to achieve this goal include improved cropping mix incentives, groundwater – surface water substitution, intra and inter-seasonal water trading and harmonisation of on- and off-farm storage, distribution, application and drainage infrastructure with environmental outcomes. Each of these options will impact in some way on irrigation and wider communities. In this paper ‘community’ involvement in setting irrigation research agendas and evaluating water management options in the Murrumbidgee Valley, Australia is explored. A brief assessment of social acceptability, combined with hydrological and economic models, was found to be an effective approach for scoping different irrigation demand management options to improve seasonality of flows. In this study the value of articulating assessment criteria when dealing with new and potentially disruptive options for the management of irrigation demand in a catchment context is demonstrated.Keywords: social acceptability, system harmonisation, conjunctive management of surface and groundwater, seasonality of flows, environmental managemen

'Dumping grounds' or a meaningful educational experience? : the involvement of Scotland's colleges in the education of disengaged young people

The research examines the discourses surrounding disengaged young people, particularly those under the age of 16, and the role of Scotland’s Colleges in making provision for them. Consideration is given to the voices of the young people themselves: how their college experiences compare to school and how they view themselves over this transition period. Consideration is also given to the policy in this area and how it has developed since the Beattie watershed of 1999. The debate surrounding the involvement of colleges in the provision of education for this group of young people touches on issues of social justice and the construction of children and young people, as well as throwing up questions about the roles and identity of Scotland’s schools and colleges. Among the questions it raises about colleges, it raises issues of pedagogy and of the professional status of its teaching staff and offers recommendations about the lessons each sector might learn from the other . Ultimately, it proposes that Scotland’s Colleges are uniquely placed to seek ascendancy in the post-school sector, welcoming and developing the role that they now play in the transition of young people to adulthood.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Editorial : The Challenges of Interdisciplinary Publishing

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The context, influences and challenges for undergraduate nurse clinical education: Continuing the dialogue

Introduction – Approaches to clinical education are highly diverse and becoming increasingly complex to sustain in complex milieu Objective – To identify the influences and challenges of providing nurse clinical education in the undergraduate setting and to illustrate emerging solutions. Method: A discursive exploration into the broad and varied body of evidence including peer reviewed and grey literature. Discussion - Internationally, enabling undergraduate clinical learning opportunities faces a range of challenges. These can be illustrated under two broad themes: (1) Legacies from the past and the inherent features of nurse education and (2) Challenges of the present, including, population changes, workforce changes, and the disconnection between the health and education sectors. Responses to these challenges are triggering the emergence of novel approaches, such as collaborative models. Conclusion(s) – Ongoing challenges in providing accessible, effective and quality clinical learning experiences are apparent

Interval analysis applied to dielectric spectroscopy: a guaranteed parameter estimation

Dielectric spectra of materials are often difficult to analyze since the common software algorithms and line shape functions do not always provide unambiguous data for the fitted parameters. In particular, this article deals with epoxy/ceramics nano-prepolymers studied by dielectric spectroscopy. In this situation, both system (the prepolymer with nanofillers) and method (the dielectric spectroscopy) are complex. Taking into account the experimental error of each data point in the measured dielectric spectrum, the sofware based on a global optimization algorithm which uses interval analysis, provides a confidence interval for every parameter of the dielectric function implemented in the software. Then, this software is able to deliver and guarantee the number of relaxation processes even if they are in part masked by other phenomena like conductivity or electrode polarization

The Sar1 Gtpase Coordinates Biosynthetic Cargo Selection with Endoplasmic Reticulum Export Site Assembly

Cargo selection and export from the endoplasmic reticulum is mediated by the COPII coat machinery that includes the small GTPase Sar1 and the Sec23/24 and Sec13/31 complexes. We have analyzed the sequential events regulated by purified Sar1 and COPII coat complexes during synchronized export of cargo from the ER in vitro. We find that activation of Sar1 alone, in the absence of other cytosolic components, leads to the formation of ER-derived tubular domains that resemble ER transitional elements that initiate cargo selection. These Sar1-generated tubular domains were shown to be transient, functional intermediates in ER to Golgi transport in vitro. By following cargo export in live cells, we show that ER export in vivo is also characterized by the formation of dynamic tubular structures. Our results demonstrate an unanticipated and novel role for Sar1 in linking cargo selection with ER morphogenesis through the generation of transitional tubular ER export sites