The accuracy of parameter estimation from noisy data, with application to resonance peak estimation in distributed Brillouin sensing

Distributed Brillouin sensing of strain and temperature works by making spatially resolved measurements of the position of the measurand-dependent extremum of the resonance curve associated with the scattering process in the weakly nonlinear regime. Typically, measurements of backscattered Stokes intensity (the dependent variable) are made at a number of predetermined fixed frequencies covering the design measurand range of the apparatus and combined to yield an estimate of the position of the extremum. The measurand can then be found because its relationship to the position of the extremum is assumed known. We present analytical expressions relating the relative error in the extremum position to experimental errors in the dependent variable. This is done for two cases: (i) a simple non-parametric estimate of the mean based on moments and (ii) the case in which a least squares technique is used to fit a Lorentzian to the data. The question of statistical bias in the estimates is discussed and in the second case we go further and present for the first time a general method by which the probability density function (PDF) of errors in the fitted parameters can be obtained in closed form in terms of the PDFs of the errors in the noisy data.

Comparative analysis of BER estimation methods in numerical simulation of 40-Gb/s RZ-DPSK transmission with in-line SOAs

Applying direct error counting, we compare the accuracy and evaluate the validity of different available numerical approaches to the estimation of the bit-error rate (BER) in 40-Gb/s return-to-zero differential phase-shift-keying transmission. As a particular example, we consider a system with in-line semiconductor optical amplifiers. We demonstrate that none of the existing models has an absolute superiority over the others. We also reveal the impact of the duty cycle on the accuracy of the BER estimates through the differently introduced Q-factors. © 2007 IEEE.

Changing treaty and changing economic context:the dynamic relationship of the legislature and the judiciary in the pursuit of capital liberalisation

Introduction For a significant period of time (the late 1950s--1980s), a lack of capital freedom was a major obstacle to the progress of the internal market project. The free movements of goods, persons and services were achieved, and developed, primarily through the case law of the Court of Justice of the European Union (CJEU). On the other hand, the Court played a (self-imposed) limited role in the development of the free movement of capital. It was through a progressive series of legislation that the freedom was finally achieved. John Usher has noted that the consequence of this is that ‘free movement of capital thus became the only Treaty “freedom” to be achieved in the manner envisaged in the Treaty’. For this reason, the relationship of the Court and legislature in this area is of particular importance in the broader context of the internal market. The rest of this chapter is split into four sections and will attempt to describe (and account for) the differing relationships between the legislature and the judiciary during the different stages of capital liberalisation. Section 2 will deal with the situation under the original Treaty of Rome. Section 3 will examine a single legislative intervention: Directive 88/361. It was this intervention that contained the obligation for Member States to fully liberalise capital movements. It is therefore the most important contribution to the completion of the internal market in the capital sphere. An examination will be made of whether the interpretation of the Directive demonstrates a changed (or changing attitude) of the Court towards the EU legislature. Section 4 will examine the changes brought about by the Treaty on European Union in 1993. It was at Maastricht that the Member States finally introduced into the Treaty framework an absolute obligation to liberalise capital movements. Finally, Section 5 will consider the Treaty of Lisbon and the possibility of future interventions by the legislature. By looking at the patterns that run through the different parts, this chapter will attempt to engage with the question of whether the approaches were products of their historical context, or whether they can be applied to other areas within the capital movement sphere.

Cramer-Rao bound analysis of location estimation in multi-hop wireless sensor networks

Location estimation is important for wireless sensor network (WSN) applications. In this paper we propose a Cramer-Rao Bound (CRB) based analytical approach for two centralized multi-hop localization algorithms to get insights into the error performance and its sensitivity to the distance measurement error, anchor node density and placement. The location estimation performance is compared with four distributed multi-hop localization algorithms by simulation to evaluate the efficiency of the proposed analytical approach. The numerical results demonstrate the complex tradeoff between the centralized and distributed localization algorithms on accuracy, complexity and communication overhead. Based on this analysis, an efficient and scalable performance evaluation tool can be designed for localization algorithms in large scale WSNs, where simulation-based evaluation approaches are impractical. © 2013 IEEE.

Illiquidity shocks and the comovement between stocks:new evidence using smooth transition

This paper extends the smooth transition conditional correlation model by studying for the first time the impact that illiquidity shocks have on stock market return comovement. We show that firms that experience shocks that increase illiquidity are less liquid than firms that experience shocks that decrease illiquidity. Shocks that increase illiquidity have no statistical impact on comovement. However, shocks that reduce illiquidity lead to a fall in comovement, a pattern that becomes stronger as the illiquidity of the firm increases. This discovery is consistent with increased transparency and an improvement in price efficiency. We find that a small number of firms experience a double illiquidity shock. For these firms, at the first shock, a rise in illiquidity reduces comovement while a fall in illiquidity raises comovement. The second shock partly reverses these changes as a rise in illiquidity is associated with a rise in comovement and a fall in illiquidity is associated with a fall in comovement. These results have important implications for portfolio construction and also for the measurement and evolution of market beta and the cost of capital as it suggests that investors can achieve higher returns for the same amount of market risk because of the greater diversification benefits that exist. We also find that illiquidity, friction, firm size and the pre-shock correlation are all associated with the magnitude of the correlation change. © 2013 Elsevier B.V.

Corporate governance disclosure in the Gulf countries

Corporate governance disclosure is important for countries aiming to attract international investors and reduce companies’ cost of capital. The relationship between corporate governance disclosure (CGD) and its determinants is the main objective of the current research. Accordingly, the research aimed to: (i) assess CGD level in the Gulf countries; (ii) investigate the impact of ownership structure (proportion of institutional, governmental, managerial and family ownership) on CGD; (iii) explore the effect of board characteristics (proportion of independent board members, proportion of family members on board, CEO/chairman duality and board size) on CGD; (iv) examine the relationship between diversity (proportion of foreign and female members on a board and in the senior management team) and CGD; and (v) test the association between firm characteristics (company size, age, liquidity, profitability, leverage, industry and auditor types) and CGD. Gulf countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates) were selected for the study since they share similar characteristics and represent a relatively homogeneous category in the Middle East and North African region. A CGD index of 232 items was developed and divided into six categories: ownership structure and investor rights; financial transparency and information disclosure; information on auditors; board and senior management structure and process; board committees; and finally corporate behaviour and responsibility. Annual reports available for listed non-financial companies of the Gulf countries were 270 for the year 2009. The maximum CGD level was 63%, whereas the minimum was 5%, with an average disclosure level of 32%. Several regression models were conducted to enhance the robustness of the results and conclusions of the study. The results indicated that five variables had a significant positive relationship with CGD: proportion of independent members on a board, proportion of foreign members on a board, proportion of foreign members in the senior management team, auditor type and profitability. The research contributes to the literature on corporate governance voluntary disclosure in developing countries. Practical contributions consist of several recommendations to policy makers, regulators, and professional institutions in the Gulf countries.

Cost and performance analysis of new wood-fuelled power plant concepts

The objective of the thesis was to analyse several process configurations for the production of electricity from biomass. Process simulation models using AspenPlus aimed at calculating the industrial performance of power plant concepts were built, tested, and used for analysis. The criteria used in analysis were performance and cost. All of the advanced systems appear to have higher efficiencies than the commercial reference, the Rankine cycle. However, advanced systems typically have a higher cost of electricity (COE) than the Rankine power plant. High efficiencies do not reduce fuel costs enough to compensate for the high capital costs of advanced concepts. The successful reduction of capital costs would appear to be the key to the introduction of the new systems. Capital costs account for a considerable, often dominant, part of the cost of electricity in these concepts. All of the systems have higher specific investment costs than the conventional industrial alternative, i.e. the Rankine power plant; Combined beat and power production (CUP) is currently the only industrial area of application in which bio-power costs can be considerably reduced to make them competitive. Based on the results of this work, AsperiPlus is an appropriate simulation platform. How-ever, the usefulness of the models could be improved if a number of unit operations were modelled in greater detail. The dryer, gasifier, fast pyrolysis, gas engine and gas turbine models could be improved.

An Exploration of parametric software cost estimating models for Jackson Systems Development

Most parametric software cost estimation models used today evolved in the late 70's and early 80's. At that time, the dominant software development techniques being used were the early 'structured methods'. Since then, several new systems development paradigms and methods have emerged, one being Jackson Systems Development (JSD). As current cost estimating methods do not take account of these developments, their non-universality means they cannot provide adequate estimates of effort and hence cost. In order to address these shortcomings two new estimation methods have been developed for JSD projects. One of these methods JSD-FPA, is a top-down estimating method, based on the existing MKII function point method. The other method, JSD-COCOMO, is a sizing technique which sizes a project, in terms of lines of code, from the process structure diagrams and thus provides an input to the traditional COCOMO method.The JSD-FPA method allows JSD projects in both the real-time and scientific application areas to be costed, as well as the commercial information systems applications to which FPA is usually applied. The method is based upon a three-dimensional view of a system specification as opposed to the largely data-oriented view traditionally used by FPA. The method uses counts of various attributes of a JSD specification to develop a metric which provides an indication of the size of the system to be developed. This size metric is then transformed into an estimate of effort by calculating past project productivity and utilising this figure to predict the effort and hence cost of a future project. The effort estimates produced were validated by comparing them against the effort figures for six actual projects.The JSD-COCOMO method uses counts of the levels in a process structure chart as the input to an empirically derived model which transforms them into an estimate of delivered source code instructions.