Cost-Effective Model Predictive Control Techniques for Modular Multilevel Converters

In this thesis, model predictive control (MPC) techniques are investigated with their applications to modular multilevel converters (MMCs). Since normally a large number of submodule (SM) capacitor voltages and gate signals need to be handled in an MMC, the MPC schemes studied in this thesis are employed for determining only the voltage levels of converter arms, while gate signals are subsequently generated by the conventional sorting method. Emphasis is given to inner-loop current control in terms of phase current and circulating current, aiming at performance enhancement and computation reduction. A variable rounding level control (VRLC) approach is developed in this thesis, which is based on a modification of the conventional nearest level control (NLC) scheme: instead of the conventional nearest integer function, a proper rounding function is selected for each arm of the MMC employing the MPC method. As a result, the simplicity of the NLC is maintained while the current regulating ability is improved. The VRLC technique can also be generalized from an MPC perspective. Different current controllers can be considered to generate the arm voltage references as input of the VRLC block, thus refining the control sets of the MPC. Based on the decoupled current models, the accumulated effect of SM capacitor voltage ripples is investigated, revealing that the VRLC strategy may not achieve a proper performance if the accumulated ripple is nontrivial compared to the voltage per level. Two indexes are also proposed for quantifying the current controllability of the VRLC. Benefiting from this analysis, A SM-grouping solution is put forward to apply such MPC techniques to an MMC with a large number of SMs, leading to an equivalent operation of an MMC with much reduced number of SMs, which significantly increases the current regulating capability with reduced complexity. As an example, the SM-grouping VRLC proposal is analyzed and its system design principles are described. This thesis also develops another MPC technique which directly optimizes the cost function using quadratic programming technique. Both a rigorous and a simplified procedure are provided to solve the optimization problem. Compared with the conventional finite control set (FCS)-MPC method which evaluates all voltage level combinations, the proposed scheme presents apparent advantage in terms of calculation cost while achieving similar performance

Splitting of surface defect partition functions and integrable systems

We study Bethe/gauge correspondence at the special locus of Coulomb moduli where the integrable system exhibits the splitting of degenerate levels. For this investigation, we consider the four-dimensional pure $\mathcal{N}=2$ supersymmetric $U(N)$ gauge theory, with a half-BPS surface defect constructed with the help of an orbifold or a degenerate gauge vertex. We show that the non-perturbative Dyson-Schwinger equations imply the Schr\"odinger-type and the Baxter-type differential equations satisfied by the respective surface defect partition functions. At the special locus of Coulomb moduli the surface defect partition function splits into parts. We recover the Bethe/gauge dictionary for each summand.Comment: 34 pages, 2 figures; v2. published versio

Dynamic Validation Logic Generation using Business Rules Management Systems

Input validation in web applications represents an important part of their functionality. With proper validation we ensure that provided input data is in accordance with technical constraints, defined by the developer and with business-related constraints. In web development frameworks, validation logic is coupled with program code. If one validation rule is changed, application needs to be recompiled and redeployed. In this thesis we developed a system for input validation based on business rules management system. Validation rules are stored in central repository, separated from implementation of web applications. Thus, we have achieved a simple and transparent way of declaring validation logic in the form of declarative business rules as well as simplifed applications maintenance in case of changes in validation logic

The risk of falling into poverty after developing heart disease: a survival analysis

Background: Those with a low income are known to have a higher risk of developing heart disease. However, the inverse relationship – falling into income poverty after developing heart disease has not been explored with longitudinal data. This paper aims to determine if those with heart disease have an elevated risk of falling into poverty.\ud \ud Methods: Survival analysis was conducted using the longitudinal Household Income and Labour Dynamics in Australia survey, between the years 2007 and 2012. The study focused on the Australian population aged 21 years and over in 2007 who were not already in poverty and did not already have heart disease, who were followed from 2007 to 2012. Cox regression models adjusting for age, sex and time-varying co-variates (marital status, home ownership and remoteness of area of residence) were constructed to assess the risk of falling into poverty.\ud \ud Results: For those aged 20 who developed heart disease, the hazard ratio for falling into income poverty was 9.24 (95 % CI: 8.97–9.51) and for falling into multidimensional poverty the hazard ratio was 14.21 (95 % CI: 13.76–14.68); for those aged 40 the hazard ratio for falling into income poverty was 3.45 (95 % CI: 3.39–3.51) and for multidimensional poverty, 5.20 (95 % CI: 5.11–5.29); and for those aged 60 the hazard ratio for falling into income poverty was 1.29 (95 % CI: 1.28–1.30) and for multidimensional poverty, 1.52 (95 % CI: 1.51–1.54), relative those who never developed heart disease. The risk for both income and multidimensional poverty decreases with age up to the age of 70, over which, those who developed heart disease had a reduced risk of poverty.\ud \ud Conclusion: For those under the age of 70, developing heart disease is associated with an increased risk of falling into both income poverty and multidimensional poverty.\u

Clutter-Contaminated Signal Recovery in Spectral Domain for Polarimetric Weather Radar

The use of spectral polarimetric filters in the range-Doppler domain shows great promise for clutter mitigation in weather radar applications. One limitation of these filters is that they cannot deal with situations in which ground clutter and precipitation overlap. In this letter, we propose a new signal recovery technique based on kriging in the spectral domain to recover the precipitation in clutter-contaminated areas. Using synthetic radar data, we test our new method and compare its performance to that of Gaussian model adaptive processing and bilinear interpolation. Our results indicate that kriging is the most accurate and robust technique out of the three.Atmospheric Remote Sensin

Spectral Polarimetric Filter Design for Wind Turbine Clutter Suppression

Nowadays, there is an intensive use of wind turbines worldwide to generate green and renewable energy. In addition, the sizes of wind turbines keep increasing for higher efficiency. However, echoes from wind turbines are severe clutter for weather radar, deteriorating its performance significantly. In this work, the spectral polarimetric filters (SPFs) are designed to mitigate wind turbine clutter (WTC). The SPFs consist of the moving double spectral linear depolarization ratio (MDsLDR) filter [1] and the object-orientated spectral polarimetric (OBSpol) filter [2], which have been previously proposed to mitigate the narrow-band clutter (both stationary and moving) for polarimetric radar with and without cross-polar measurements, respectively. Data collected by a polarimetric Doppler weather radar known as the IRCTR Drizzle Radar (IDRA) are used to validate the performance of the proposed algorithm. Mounted on the top of a 213m tower in Cabauw Experimental Site for Atmospheric Research, the Netherlands, the X-band operational research radar is still affected by wind turbines which are 120m in height and 3400m far away. Different case studies demonstrate the good performance of the SPFs in sidelobe WTC suppression. Moreover, these filters can be applied in real time due to its low computation complexity

Imagining a future: changing the landscape for third space professionals in Australian higher education institutions

In the last decade there has been a shift in the discourses around professional staff in higher education that has been influenced by neoliberal agenda that focused on driving education reforms. Earlier discussions centring around nomenclature variations have progressed to those about creating and developing borderless professionals operating in the third space – a notional space where professional staff and academic staff with diverse and valuable skills work as equal professional partners on complex and multifaceted projects. This article looks at the evolution of the debates around professional staff. It considers how the notions of professionalism and professionalisation are being reconceptualised in the third space. Discussion progresses towards capability building and developmental opportunities of aspiring third space professional staff in higher education settings. Possible pathways of engaging with and empowering professional staff in designing their future careers and professional identities are considered. Building a community of research practices under the auspices of the Association for Tertiary Education Management (ATEM) and engaging postgraduate students in the university third space project work are proposed as potential areas for further research in the field of professional staff capability building

The inherent vulnerability of the Australian Curriculum's cross-curriculum priorities

National curriculum development is a complex and contested process. By its very function, a national curriculum serves to organise diverse interests into a common framework, a task fraught with cultural and political tensions and compromises. In the emergent Australian Curriculum these tensions are manifest in and around the cross-curriculum priorities (CCPs): sustainability, Asia and Australia’s engagement with Asia, and Aboriginal and Torres Strait Islander histories and cultures. These priorities have been under fire since their introduction to the curriculum and the announcement of a review of the emerging curriculum prompted fears of a renewed attack. Studies from diverse fields of education research suggest that a lack of high-level institutional support for initiatives such as the CCPs places them in jeopardy. This paper focuses on two priorities: Asia and Australia's engagement with Asia, and Aboriginal and Torres Strait Islander histories and cultures. It employs interest convergence theory as a framework to understand connections between the intentions behind the inclusion of the CCPs and the outcomes of the Review of the Australian Curriculum. Furthermore, this paper draws on interview-based research that explores how the priorities are constructed by those who are expected to work with them, from pre-service through to experienced teachers. This theoretical framework provides an explanation for the perennially precarious nature of these kinds of curriculum initiatives