Frequency Domain Characterization Of Sliding Mode Control Of An Inverter Used In DSTATCOM Application

In this paper, the commonly used switching schemes for sliding mode control of power converters is analyzed and designed in the frequency domain. Particular application of a distribution static compensator (DSTATCOM) in voltage control mode is investigated in a power distribution system. Tsypkin's method and describing function is used to obtain the switching conditions for the two-level and three-level voltage source inverters. Magnitude conditions of carrier signals are developed for robust switching of the inverter under carrier-based modulation scheme of sliding mode control. The existence of border collision bifurcation is identified to avoid the complex switching states of the inverter. The load bus voltage of an unbalanced three-phase nonstiff radial distribution system is controlled using the proposed carrier-based design. The results are validated using PSCAD/EMTDC simulation studies and through a scaled laboratory model of DSTATCOM that is developed for experimental verification

The short-term effect of air pollution on cardiovascular mortality in Tianjin, China : comparison of time series and case–crossover analyses

Background: Many studies have illustrated that ambient air pollution negatively impacts on health. However, little evidence is available for the effects of air pollution on cardiovascular mortality (CVM) in Tianjin, China. Also, no study has examined which strata length for the time-stratified case–crossover analysis gives estimates that most closely match the estimates from time series analysis. Objectives: The purpose of this study was to estimate the effects of air pollutants on CVM in Tianjin, China, and compare time-stratified case–crossover and time series analyses. Method: A time-stratified case–crossover and generalized additive model (time series) were applied to examine the impact of air pollution on CVM from 2005 to 2007. Four time-stratified case–crossover analyses were used by varying the stratum length (Calendar month, 28, 21 or 14 days). Jackknifing was used to compare the methods. Residual analysis was used to check whether the models fitted well. Results: Both case–crossover and time series analyses show that air pollutants (PM10, SO2 and NO2) were positively associated with CVM. The estimates from the time-stratified case–crossover varied greatly with changing strata length. The estimates from the time series analyses varied slightly with changing degrees of freedom per year for time. The residuals from the time series analyses had less autocorrelation than those from the case–crossover analyses indicating a better fit. Conclusion: Air pollution was associated with an increased risk of CVM in Tianjin, China. Time series analyses performed better than the time-stratified case–crossover analyses in terms of residual checking.

What is the impact of land tenure on the sustainability of retirement village communities in Australia?

In 2005, 17.3% of Australians were aged 60 years and older according to the Australian Bureau of statistics (ABS). According to aBS this situation mirrors the poulation profile of other developed countries such as Canada, New Zealand, the United States of America and to some extent the United Kingdom (ABS). Self contained independent living units in retirement Villages are now contributing to the dwellings available for those aged 55 years and over in Australia and the retirement village sector has become a significant sector within the residential property market. However, the method of operaton of many retirement villages, and the lack of freehold tenure, impacts on the desireability of retirement village life to potential residents. This paper focuses on sustainability from the perspective of the ongoing viability of retirement village operations in light of the impact of land tenure and operational issues on the perceptions of potential residents.

The global division of labour and the division in global labour

Since the 1980s the locus of manufacturing and some services have moved to countries of the Global South. Liberalization of trade and investment has added two billion people to world labour supply and brought workers everywhere into intense competition with each other. Under orthodox neoliberal and neoclassical approaches free trade and open investment should benefit all countries and lead to convergence. However considerable differences in wages and working hours exist between workers of the Global North and those of the Global South. The organising question for the thesis is why workers in different countries but the same industries get different wages. Empirical evidence reviewed in the thesis shows that productivity does not explain these wage differences and that workers in some parts of the South are more productive than workers in the North. Part of the thesis examines the usefulness of explanations drawn from Marxist, institutionalist and global commodity chain approaches. There is a long established argument in Marxist and neo-Marxist writings that differences between North and South result from imperialism and the exercise of power. This is the starting point to review ways of understanding divisions between workers as the outcome of a global class structure. In turn, a fault line is postulated between productive and unproductive labour that largely replicates the division between the Global North and the Global South. Workers and their organizations need shared actions if they are to resist global competition and wage disparities. Solidarity has been the clarion of progressive movements from the Internationals of the early C19th through to the current Global Unions and International Confederation of Trade Unions (ICTU). The thesis examines how nationalism and particular interests have undermined solidarity and reviews the major implications for current efforts to establish and advance a global labour position.

Re-thinking how we plan to address technically complex problems : drawing on planning theory to guide practice in revision of land use plans in coastal high hazard zones

Queensland's new State Planning Policy for Coastal Protection, released in March and approved in April 2011 as part of the Queensland Coastal Plan, stipulates that local governments prepare and implement adaptation strategies for built up areas projected to be subject to coastal hazards between present day and 2100. Urban localities within the delineated coastal high hazard zone (as determined by models incorporating a 0.8 meter rise in sea level and a 10% increase in the maximum cyclone activity) will be required to re-evaluate their plans to accommodate growth, revising land use plans to minimise impacts of anticipated erosion and flooding on developed areas and infrastructure. While implementation of such strategies would aid in avoidance or minimisation of risk exposure, communities are likely to face significant challenges in such implementation, especially as development in Queensland is so intensely focussed upon its coasts with these new policies directing development away from highly desirable waterfront land. This paper examines models of planning theory to understand how we plan when faced with technically complex problems towards formulation of a framework for evaluating and improving practice.

Raising awareness of traffic pollution: the potential benefits and problems of using a warning smell

Exposure to traffic pollution is increasing worldwide as people move to cities, and as more vehicles join the roads, creating longer journeys and more traffic jams. Most traffic pollutants are odourless and invisible, which hides exposure from the public. If traffic pollution had a distinctive smell it would enable people to avoid exposure, and increase the political will for difficult policy changes. A smell may also instigate longer-term changes, such as switching to active transport for school pick-ups. A smell could be added using a fuel additive or a temporary device attached to vehicle exhausts.

A framework for analysing system intelligence of the building control system: a study of the integrated building management system

The lack of satisfactory consensus for characterizing the system intelligence and structured analytical decision models has inhibited the developers and practitioners to understand and configure optimum intelligent building systems in a fully informed manner. So far, little research has been conducted in this aspect. This research is designed to identify the key intelligent indicators, and develop analytical models for computing the system intelligence score of smart building system in the intelligent building. The integrated building management system (IBMS) was used as an illustrative example to present a framework. The models presented in this study applied the system intelligence theory, and the conceptual analytical framework. A total of 16 key intelligent indicators were first identified from a general survey. Then, two multi-criteria decision making (MCDM) approaches, the analytic hierarchy process (AHP) and analytic network process (ANP), were employed to develop the system intelligence analytical models. Top intelligence indicators of IBMS include: self-diagnostic of operation deviations; adaptive limiting control algorithm; and, year-round time schedule performance. The developed conceptual framework was then transformed to the practical model. The effectiveness of the practical model was evaluated by means of expert validation. The main contribution of this research is to promote understanding of the intelligent indicators, and to set the foundation for a systemic framework that provide developers and building stakeholders a consolidated inclusive tool for the system intelligence evaluation of the proposed components design configurations.

Unlocking risk allocation and equitable conversion : reform of the passing of risk in the sale of land

The principles relating to the passing of risk under a contract for the sale of real property would seem to have been long settled. The rule under the general law is that the risk of loss of the subject matter under a contract for the sale of real property passes to the buyer upon the creation of a valid and binding contract. This article considers the origin of that rule, how it developed with the growth of equity, and advances the view that it is anomalous in a modern context of property dealings. In doing so, the article adverts to the variety of statutory mechanisms used to subvert the rule, few of which are of practical value. It concludes that the rule is outmoded in many respects and suggests a number of reforms which might be implemented nationally to bring consistency and simplicity to the issue of damage or destruction of improvements which are the subject of a land contract.

Inadequacy of land use and impervious area fraction for determining urban stormwater quality

Urban stormwater quality is multifaceted and the use of a limited number of factors to represent catchment characteristics may not be adequate to explain the complexity of water quality response to a rainfall event or site-to-site differences in stormwater quality modelling. This paper presents the outcomes of a research study which investigated the adequacy of using land use and impervious area fraction only, to represent catchment characteristics in urban stormwater quality modelling. The research outcomes confirmed the inadequacy of the use of these two parameters alone to represent urban catchment characteristics in stormwater quality prediction. Urban form also needs to be taken into consideration as it was found have an important impact on stormwater quality by influencing pollutant generation, build-up and wash-off. Urban form refers to characteristics related to an urban development such as road layout, spatial distribution of urban areas and urban design features.

Regulation of land access for resource development: A coal seam gas case study from Queensland

A number of regulatory statutes provide for agreements with landowners which are given extended effect, that is, are binding upon the landowner’s successors (‘statutory agreements’). Several Queensland statutes require a project proponent to enter into a statutory agreement with a landowner before a resource development activity can be carried out on private land or by accessing private land. Provisions of Queensland’s Petroleum and Gas (Production and Safety) Act 2004 make certain types of statutory agreements binding upon successors and assigns of the landowner, but do not clearly prescribe the nature and contents of an agreement, nor require that the agreement be recorded on the land title or petroleum register. If statutory agreements are to be used for such purposes, their purpose and content should be more clearly defined by statute and they should be recorded on a searchable register.