B-spline neural network based digital baseband predistorter solution using the inverse of De Boor algorithm

In this paper a new nonlinear digital baseband predistorter design is introduced based on direct learning, together with a new Wiener system modeling approach for the high power amplifiers (HPA) based on the B-spline neural network. The contribution is twofold. Firstly, by assuming that the nonlinearity in the HPA is mainly dependent on the input signal amplitude the complex valued nonlinear static function is represented by two real valued B-spline neural networks, one for the amplitude distortion and another for the phase shift. The Gauss-Newton algorithm is applied for the parameter estimation, in which the De Boor recursion is employed to calculate both the B-spline curve and the first order derivatives. Secondly, we derive the predistorter algorithm calculating the inverse of the complex valued nonlinear static function according to B-spline neural network based Wiener models. The inverse of the amplitude and phase shift distortion are then computed and compensated using the identified phase shift model. Numerical examples have been employed to demonstrate the efficacy of the proposed approaches.

Small business legislation in Australia: does it provide a solution to part of the UK lease reform debate?

This paper addresses the commercial leases policy issue of how to deal with small business tenants. The UK has adopted a voluntary solution to commercial lease reform by using Codes of Practice which is in contrast to the legislative approach adopted by Australia to attempt to solve its perceived problems with small business retail tenancies. The major aim of the research was to examine the perceptions of the effectiveness of the legislation in Australia and discuss any implications for the UK policy debate but the results of the research also raise questions for the Australian regime. The research used a combination of literature and legislation review and a semi structured interview survey to investigate the policy aims and objectives of Australian Federal and State Governments, identify the nature and scope of the Australian legislation and examine perceptions of effectiveness of the legislation in informing small business tenants. The situation is complicated in Australia due to leases being a State rather than Federal responsibility therefore the main fieldwork was carried out in one case study State, Victoria. The paper concludes that some aspects of the Australian system can inform the UK policy debate including mandatory information provision at the commencement of negotiations and the use of lease registrars/commissioners. However, there are a number of issues that the Australian legislation does not appear to have successfully addressed including the difficulties of legislating across partial segments of the commercial property market and the collection of data for enforcement purposes.

Model-based groupware solution for distributed real-time collaborative 4D planning via teamwork

Construction planning plays a fundamental role in construction project management that requires team working among planners from a diverse range of disciplines and in geographically dispersed working situations. Model-based four-dimensional (4D) computer-aided design (CAD) groupware, though considered a possible approach to supporting collaborative planning, is still short of effective collaborative mechanisms for teamwork due to methodological, technological and social challenges. Targeting this problem, this paper proposes a model-based groupware solution to enable a group of multidisciplinary planners to perform real-time collaborative 4D planning across the Internet. In the light of the interactive definition method, and its computer-supported collaborative work (CSCW) design analysis, the paper discusses the realization of interactive collaborative mechanisms from software architecture, application mode, and data exchange protocol. These mechanisms have been integrated into a groupware solution, which was validated by a planning team in a truly geographically dispersed condition. Analysis of the validation results revealed that the proposed solution is feasible for real-time collaborative 4D planning to gain a robust construction plan through collaborative teamwork. The realization of this solution triggers further considerations about its enhancement for wider groupware applications.

A titration model: an analysis and solution

The Newton‐Raphson method is proposed for the solution of the nonlinear equation arising from a theoretical model of an acid/base titration. It is shown that it is necessary to modify the form of the equation in order that the iteration is guaranteed to converge. A particular example is considered to illustrate the analysis and method, and a BASIC program is included that can be used to predict the pH of any weak acid/weak base titration.