A generalized estimating equations approach for analysis of the impact of new technology on a trawl fishery

The article describes a generalized estimating equations approach that was used to investigate the impact of technology on vessel performance in a trawl fishery during 1988-96, while accounting for spatial and temporal correlations in the catch-effort data. Robust estimation of parameters in the presence of several levels of clustering depended more on the choice of cluster definition than on the choice of correlation structure within the cluster. Models with smaller cluster sizes produced stable results, while models with larger cluster sizes, that may have had complex within-cluster correlation structures and that had within-cluster covariates, produced estimates sensitive to the correlation structure. The preferred model arising from this dataset assumed that catches from a vessel were correlated in the same years and the same areas, but independent in different years and areas. The model that assumed catches from a vessel were correlated in all years and areas, equivalent to a random effects term for vessel, produced spurious results. This was an unexpected finding that highlighted the need to adopt a systematic strategy for modelling. The article proposes a modelling strategy of selecting the best cluster definition first, and the working correlation structure (within clusters) second. The article discusses the selection and interpretation of the model in the light of background knowledge of the data and utility of the model, and the potential for this modelling approach to apply in similar statistical situations.

Development of a novel experimental model to investigate the influence of mechanics on bone healing

This dissertation proposed a novel experimental model combining a defect configuration with an active instrumented fixation device to investigate the influence of mechanics on bone healing. The proposed defect configuration aimed to minimise physiological loading within an experimental fracture gap and the instrumented fixator was used for the application of controlled displacements and in vivo stiffness monitoring of the healing process. This thesis has provided a novel approach to advance current knowledge and understanding of mechanobiology, which has been limited in previous experimental models.

Depositional model for the early Miocene turbidite sequence, the Whakataki Formation, NZ

This research examined the influence of tectonic activity on submarine sedimentation processes, through a deposit-based analysis of turbidites in outcrop. A comprehensive field study of the Miocene Whakataki Formation yielded significant data that was analysed using methods of process-sedimentology, stratigraphy, and ichnology. Signatures of the tectonically active depositional environment were identifiable at very high resolution, from grain composition and texture to trace-fossil assemblages, as well as on a broader-scale in stratigraphic stacking patterns and structural deformation. From these results and environmental interpretations, an original facies characterisation and conceptual depositional model have been established.

An integrated model of an open-pit coal mine: Improving energy efficiency decisions

This article contributes an original integrated model of an open-pit coal mine for supporting energy-efficient decisions. Mixed integer linear programming is used to formulate a general integrated model of the operational energy consumption of four common open-pit coal mining subsystems: excavation and haulage, stockpiles, processing plants and belt conveyors. Mines are represented as connected instances of the four subsystems, in a flow sheet manner, which are then fitted to data provided by the mine operators. Solving the integrated model ensures the subsystems’ operations are synchronised and whole-of-mine energy efficiency is encouraged. An investigation on a case study of an open-pit coal mine is conducted to validate the proposed methodology. Opportunities are presented for using the model to aid energy-efficient decision-making at various levels of a mine, and future work to improve the approach is described.

Future learning landscapes for architectural education: Linking space, place, pedagogy, technology + context

Diversification and expansion of global higher education in the 21st century, has resulted in Learning Landscapes for architectural education that can no longer be sustained by the traditional model. Changes have resulted because of surging student numbers, extensions to traditional curricula, evolving competency standards and accreditation requirements, and modified geographical and pedagogical boundaries. The influx of available new technology has helped to democratise knowledge, transforming when, where and how learning takes place. Pressures on government funded higher education budgets highlight the need for a critical review of the current approach to the design and use of learning environments. Efficient design of physical space contributes significantly to savings in provision, management and use of facilities, while also potentially improving pedagogical quality. The purpose of this research is to identify emerging trends in the design of future Learning Landscapes for architectural education in Australasia; to understand where and how students of architecture are likely to learn, in the future context. It explores the important linkages between space, place, pedagogy, technology and context, using a multi methodological qualitative research approach. An Australasian context study will explore the Learning Landscapes of 23 Schools of Architecture across Australia, New Zealand and Papua New Guinea. The focus of this paper is on the methodology which is being employed to undertake dynamic data collection for the study. The research will be determined through mapping all forms of architectural learning environments, pedagogical approaches and contextual issues, to bridge the gap between academic theory, and architectural design practice. An initial understanding that pedagogy is an intrinsic component imbedded within the design of learning environments, will play an important role. Active learning environments which are exemplified by the architectural design studio, support dynamic project based and collaborative connected learning models. These have recently become a lot more common in disciplines outside of design and the arts. It is anticipated, therefore, that the implications for this research may well have a positive impact far beyond the confines of the architectural studio learning environment.

How to design educational settings to promote collaborative inquiry: Pedagogical infrastructures for technology-enhanced progressive inquiry

Strategies of scientific, question-driven inquiry are stated to be important cultural practices that should be educated in schools and universities. The present study focuses on investigating multiple efforts to implement a model of Progressive Inquiry and related Web-based tools in primary, secondary and university level education, to develop guidelines for educators in promoting students collaborative inquiry practices with technology. The research consists of four studies. In Study I, the aims were to investigate how a human tutor contributed to the university students collaborative inquiry process through virtual forums, and how the influence of the tutoring activities is demonstrated in the students inquiry discourse. Study II examined an effort to implement technology-enhanced progressive inquiry as a distance working project in a middle school context. Study III examined multiple teachers' methods of organizing progressive inquiry projects in primary and secondary classrooms through a generic analysis framework. In Study IV, a design-based research effort consisting of four consecutive university courses, applying progressive inquiry pedagogy, was retrospectively re-analyzed in order to develop the generic design framework. The results indicate that appropriate teacher support for students collaborative inquiry efforts appears to include interplay between spontaneity and structure. Careful consideration should be given to content mastery, critical working strategies or essential knowledge practices that the inquiry approach is intended to promote. In particular, those elements in students activities should be structured and directed, which are central to the aim of Progressive Inquiry, but which the students do not recognize or demonstrate spontaneously, and which are usually not taken into account in existing pedagogical methods or educational conventions. Such elements are, e.g., productive co-construction activities; sustained engagement in improving produced ideas and explanations; critical reflection of the adopted inquiry practices, and sophisticated use of modern technology for knowledge work. Concerning the scaling-up of inquiry pedagogy, it was concluded that one individual teacher can also apply the principles of Progressive Inquiry in his or her own teaching in many innovative ways, even under various institutional constraints. The developed Pedagogical Infrastructure Framework enabled recognizing and examining some central features and their interplay in the designs of examined inquiry units. The framework may help to recognize and critically evaluate the invisible learning-cultural conventions in various educational settings and can mediate discussions about how to overcome or change them.

Membrane fractionation technologies for high quality mill sugar and value-added by products - an integrated sugar production process concept model.

Membrane filtration technology has been proven to be a technically sound process to improve the quality of clarified cane juice and subsequently to increase the productivity of crystallisation and the quality of sugar production. However, commercial applications have been hindered because the benefits to crystallisation and sugar quality have not outweighed the increased processing costs associated with membrane applications. An 'Integrated Sugar Production Process (ISPP) Concept Model' is proposed to recover more value from the non-sucrose streams generated by membrane processing. Pilot scale membrane fractionation trials confirmed the technical feasibility of separating high-molecular weight, antioxidant and reducing sugar fractions from cane juice in forms suitable for value recovery. It was also found that up to 40% of potassium salts from the juice can be removed by membrane application while removing the similar amount of water with potential energy saving in subsequent evaporation. Application of ISPP would allow sugar industry to co-produce multiple products and high quality mill sugar while eliminating energy intensive refining processes.

A hidden Markov model approach for determining vessel activity from vessel monitoring system data.

Many fisheries worldwide have adopted vessel monitoring systems (VMS) for compliance purposes. An added benefit of these systems is that they collect a large amount of data on vessel locations at very fine spatial and temporal scales. This data can provide a wealth of information for stock assessment, research, and management. However, since most VMS implementations record vessel location at set time intervals with no regard to vessel activity, some methodology is required to determine which data records correspond to fishing activity. This paper describes a probabilistic approach, based on hidden Markov models (HMMs), to determine vessel activity. A HMM provides a natural framework for the problem and, by definition, models the intrinsic temporal correlation of the data. The paper describes the general approach that was developed and presents an example of this approach applied to the Queensland trawl fishery off the coast of eastern Australia. Finally, a simulation experiment is presented that compares the misallocation rates of the HMM approach with other approaches.

A Modified Heffron-Phillip's Model for The Design of Power System Stabilizers

In this paper a modified Heffron-Phillip's (K-constant) model is derived for the design of power system stabilizers. A knowledge of external system parameters, such as equivalent infinite bus voltage and external impedances or their equivalent estimated values is required for designing a conventional power system stabilizer. In the proposed method, information available at the secondary bus of the step-up transformer is used to set up a modified Heffron-Phillip's (ModHP) model. The PSS design based on this model utilizes signals available within the generating station. The efficacy of the proposed design technique and the performance of the stabilizer has been evaluated over a range of operating and system conditions. The simulation results have shown that the performance of the proposed stabilizer is comparable to that could be obtained by conventional design but without the need for the estimation and computation of external system parameters. The proposed design is thus well suited for practical applications to power system stabilization, including possibly the multi-machine applications where accurate system information is not readily available.

A dynamic programming model for optimising feeding and slaughter decisions regarding fattening pigs

Costs of purchasing new piglets and of feeding them until slaughter are the main variable expenditures in pig fattening. They both depend on slaughter intensity, the nature of feeding patterns and the technological constraints of pig fattening, such as genotype. Therefore, it is of interest to examine the effect of production technology and changes in input and output prices on feeding and slaughter decisions. This study examines the problem by using a dynamic programming model that links genetic characteristics of a pig to feeding decisions and the timing of slaughter and takes into account how these jointly affect the quality-adjusted value of a carcass. The model simulates the growth mechanism of a pig under optional feeding and slaughter patterns and then solves the optimal feeding and slaughter decisions recursively. The state of nature and the genotype of a pig are known in the analysis. The main contribution of this study is the dynamic approach that explicitly takes into account carcass quality while simultaneously optimising feeding and slaughter decisions. The method maximises the internal rate of return to the capacity unit. Hence, the results can have vital impact on competitiveness of pig production, which is known to be quite capital-intensive. The results suggest that producer can significantly benefit from improvements in the pig's genotype, because they improve efficiency of pig production. The annual benefits from obtaining pigs of improved genotype can be more than €20 per capacity unit. The annual net benefits of animal breeding to pig farms can also be considerable. Animals of improved genotype can reach optimal slaughter maturity quicker and produce leaner meat than animals of poor genotype. In order to fully utilise the benefits of animal breeding, the producer must adjust feeding and slaughter patterns on the basis of genotype. The results suggest that the producer can benefit from flexible feeding technology. The flexible feeding technology segregates pigs into groups according to their weight, carcass leanness, genotype and sex and thereafter optimises feeding and slaughter decisions separately for these groups. Typically, such a technology provides incentives to feed piglets with protein-rich feed such that the genetic potential to produce leaner meat is fully utilised. When the pig approaches slaughter maturity, the share of protein-rich feed in the diet gradually decreases and the amount of energy-rich feed increases. Generally, the optimal slaughter weight is within the weight range that pays the highest price per kilogram of pig meat. The optimal feeding pattern and the optimal timing of slaughter depend on price ratios. Particularly, an increase in the price of pig meat provides incentives to increase the growth rates up to the pig's biological maximum by increasing the amount of energy in the feed. Price changes and changes in slaughter premium can also have large income effects. Key words: barley, carcass composition, dynamic programming, feeding, genotypes, lean, pig fattening, precision agriculture, productivity, slaughter weight, soybeans

Issues of Digital Ecosystems Approach to Biological Ecosystem Simulation Model Fit Optimization

This study examines the application of digital ecosystems concepts to a biological ecosystem simulation problem. The problem involves the use of a digital ecosystem agent to optimize the accuracy of a second digital ecosystem agent, the biological ecosystem simulation. The study also incorporates social ecosystems, with a technological solution design subsystem communicating with a science subsystem and simulation software developer subsystem to determine key characteristics of the biological ecosystem simulation. The findings show similarities between the issues involved in digital ecosystem collaboration and those occurring when digital ecosystems interact with biological ecosystems. The results also suggest that even precise semantic descriptions and comprehensive ontologies may be insufficient to describe agents in enough detail for use within digital ecosystems, and a number of solutions to this problem are proposed.