Battery clamped three-level inverter for renewable energy systems

This paper presents a novel battery direct integration scheme for renewable energy systems. The idea is to replace ordinary capacitors of a three-level flying-capacitor inverter by three battery banks to alleviate power fluctuations in renewable generation. This approach eliminates the need for interfacing dc-dc converters and thus considerably improves the overall efficiency. However, the major problem with this approach is the uneven distribution of space vectors which is due to unavoidable unbalance in clamping voltages. A detailed analysis on the effects of this issue and a novel carrier based pulse width modulation method, which can generate undistorted currents even in the presence of unevenly distributed space vectors, are presented in this paper. A charge/discharge controller is also proposed for power sharing and state of charge balancing of battery banks. Simulation results are presented to verify the efficacy of the proposed system, modulation method and power sharing controller.

Doubly Fed Induction Generator for wind energy generation using nine-switch power converter

A Three-Phase Nine-Switch Converter (NSC) topology for Doubly Fed Induction Generator in wind energy generation is proposed in this paper. This converter topology was used in various applications such as Hybrid Electric Vehicles and Uninterruptable Power Supplies. In this paper, Nine-Switch Converter is introduced in Doubly Fed Induction Generator in renewable energy application for the first time. It replaces the conventional Back-to-Back Pulse Width Modulated voltage source converter (VSC) which composed of twelve switches in many DFIG applications. Reduction in number of switches is the most beneficial in terms of cost and power switching losses. The operation principle of Nine-Switch Converter using SPWM method is discussed. The resulting NSC performance of rotor side current control, active power and reactive control are compared with Back-to Back voltage source converter performance. DC link voltage regulation using front end converter is also presented. Finally the simulation results of DFIG performances using NSC and Back-to-Back VSC are analyzed and compared.

Virtual resistance based active damping solution for constant power instability in AC microgrids

With ever-increasing share of power electronic loads constant power instability is becoming a significant issue in microgrids, especially when they operate in the islanding mode. Transient conditions like resistive load-shedding or sudden increase of constant power loads (CPL) might destabilize the whole system. Modeling and stability analysis of AC microgrids with CPLs have already been discussed in literature. However, no effective solutions are provided to stabilize this kind of system. Therefore, this paper proposes a virtual resistance based active damping method to eliminate constant power instability in AC microgrids. Advantages and limitations of the proposed method are also discussed in detail. Simulation results are presented to validate the proposed active damping solution.

Facebook Versus Ghaddafi : social networking as a tool for democratic change in Libya

The emergence of the Internet is one of the most significant leaps in the history of humanity. Information, knowledge and culture are exchanged among masses of people through interconnected information platforms. These platforms enable our culture to be analysed and rewritten, and fundamentally opens our perceptions to a wide variety of concepts and beliefs. The connected networks of the Internet have shaped a virtual — but communicative — space where people can cross borders freely within a realm characterised by the ability to go anywhere, see anything, learn, compare and understand. This chapter focuses on the Libyan experience with social networking platforms in actualising democratic change in the uprising of 17 February 2011. After briefly outlining the political and economic situation under the regime of Colonel Mummar Ghaddafi, the chapter discusses the role that social networking platforms played during the struggle of the Libyan people for democratic change. Finally, it points out the positive changes that resulted from the uprising and the potential role that social media might play in the ongoing democratization and development of Libyan society.

Mandatory reporting laws

As part of the effort to protect children from significant abuse and neglect, each state and territory in Australia has enacted legislation commonly known as "mandatory reporting laws". There is much confusion about the nature and effects of these laws, both generally and within each jurisdiction. Accordingly, the main aim of this chapter is to review and explain the legislative principles across Australia. In doing so, the chapter will identify differences between the state and territory laws and will situate the laws as part of a system of responses to the whole spectrum of child abuse and neglect. We will also highlight the need for effective reporter training and public awareness, especially given the tension between the widely perceived need for a community response to child abuse and neglect and the simultaneous concern to avoid unnecessary reporting of innocuous events and situations.

Sexual abuse prevention education

Child sexual abuse is a serious problem that has received increased attention in recent years. From an ecological perspective, in which social problems are viewed in the context of characteristics of individuals, families, and broader societal systems (Prilleltensky, Peirson, & Nelson, 2001), preventing child sexual abuse involves strengthening capacity to intervene at individual, family/relationship, school, and community levels. School-based education programs have been developed in efforts to prevent child sexual abuse before it happens and to provide children who may already be experiencing it with help seeking information. Use of these programs must be based on evidence rather than ideology. Evaluations of these programs have demonstrated that sexual abuse prevention education can provide children with improved knowledge and skills for responding to and reporting potential sexual abuse. However, this learning does not seem to be maintained over time which means further attention should be given to repeated learning, opportunities for concept reinforcement and integration with other topics. School-based programs typically present information to children by presenting a series of core concepts and messages which are delivered using engaging pedagogical strategies such as multi-media technologies, animations, theatre and songs, puppets, picture books, and games. This chapter will outline the key characteristics of effective child sexual abuse prevention programs, and will provide directions for future research and practice.

Learning in and out of university : Aboriginal and Torres Strait Islander students’ conceptions and strategies used to learn

Research suggests that students’ approaches to learning and learning outcomes are closely related to their conceptions of learning. This paper describes a phenomenographically inspired investigation into conceptions of formal learning held by 22 Aboriginal and Torres Strait Islander students from three Australian universities in Queensland; experiences of informal learning, reasons for studying and strategies used to learn were also investigated. The attrition rate for these students in tertiary education is higher than that of any other group of students. It was hoped that information gained may delineate factors that contribute to high attrition rates and therefore inform courses of action that may lead to improved teaching and learning practices for these students. Additionally, success in tertiary education for Aboriginal and Torres Strait Islander students may increase their involvement in mainstream society. Results showed that they view and approach university learning in much the same way as other university students. It was also apparent that, generally, the strategies these students used did not match the conceptions of learning they held. An interesting result was the difference between the conceptions of formal learning and explanations of informal learning

Equally engaged : demystifying tertiary study in the creative arts to equity communities

The participation rate of students from low socio-economic (SES) backgrounds into Australian universities remains low. A nationwide initiative to raise participation rates aims to stimulate interest, highlight career possibilities and enhance understanding of university. The program also aims to improve retention and completion rates of those students. This paper provides a case study and preliminary evaluation of QUT’s Creative Industries Faculty’s (CIF) outreach programs to low SES school students, operating since 2012. Programs are conducted across the disciplines of Dance, Drama, Media, Digitalstorytelling, Music and Entertainment. Presenting the arts and creative industries as a viable study / career pathway is particularly challenging to low SES groups. However, the focus on the creative industries aims to broaden understanding of arts and creativity, emphasising the significance of digital technology in the transformation of the workforce, providing new career opportunities in the creative and non-creative sectors. CIF’s outreach programs have been delivered to hundreds of students and this paper presents a case study and evaluation of several programs.

New country market feasibility analyses

Opportunity screening is also known as feasibility testing, which is the process of assessing whether a particular business opportunity is within the capacity of either an entrepreneur or an intrapreneur, and also whether it can create sustainable revenues. As the funnel diagram shows, the number of opportunities diminishes as we move to the right through the diagram. This is because not every idea identified in the opportunity identification stage as potentially interesting, and then framed into a business opportunity in the opportunity development stage, will satisfy the formal and informal screening criteria. The informal screening process occurs in all stages of the development process. For example, not every idea that has been identified will be converted into a business opportunity; similarly, not every business opportunity progresses to a feasibility test. Subsequently, only the best business opportunities are screened, and only the very best of those screened then progress to the business plan step.

Managing growth and entry strategies across borders

Should the firm move successfully into a growth or expansion phase the owner manager will be required to increase the scale and scope of its operations. Part of this expansion will involve hiring additional employees, and increasing the overall complexity of the firm's activities. It is likely that the need for greater levels of professional management will be required to operate the firm, along with the need for enhanced planning and the introduction of systems to support the new levels of complexity. The transition from a small, owner-managed firm to a large systems-managed business will require the development of a team-based management approach with greater specialisation within the management team. Corporate governance is also likely to change as the growth cycle takes place. As it grows, the business will become more formalised in its accounting, management and other systems. The need for greater quantities of capital is likely to lead the business towards equity finance. As new equity partner are taken into the company the original owner managers may find their level of control diminished. The larger the firm becomes the more likely its management structure will become decentralised with greater separation between the owner and the firm in terms of operational and financial matters.

Global outsourcing, production and logistics

Supply chains are the core of most industrial networks in which your business operates. They provide the pipeline through which the products and services flow from supplier to customer across each element within the business activity system. Global supply chain relationships have become the basis for many industries with an international network of firms engaged in the supply of goods and services that must be produced to quality standards in one country and delivered just-in-time for assembly or integration into further production processes in another country, frequently many thousands of miles apart. This topic examines the nature of supply chain management and their role in strategic networking. The previous learning tasks have focused on having the correct internal mechanism to effectively manage the inputs and outputs of the organisation by implementing an effective and transparent management system. This learning task takes a look at how management intent strategy and innovation are used to measure the external factors that influence the overall performance of the organisation and develop new strategies by understanding the business cycle and the people within your market environment.

In for the long haul : family business succession at HaulageCo

This is a case about family business succession. Because many successions fail, the 'problem of succession' is a key issue in the family business field (see Aronoff 1998; Bird eta/. 2002; Dyer & Sanchez 1998; Sharma 2004; Zalu·a & Sharma 2004). Indeed, from the non-family business literature, we know one third of relay successions - like this case where there is an identified successor - will fail, with the prospective CEO leaving before succeeding the incumbent CEO (Cmmella & Shen 2001). Research on next generation family business members is limited. Successor ath·ibutes (Chrisman, Chua & Sharma 1998; Sharma & Rao 2000), as well as various characteristics such as socialisation (Garcia-Aivmez, L6pez-Sintas & Gonzalvo 2002) a11d gender (Haberman & Danes 2007; Vera & Dean 2005) have all been considered to play a role. So too have successor intentions (Stavrou & Swiercz 1998), motivation (Le Breton-Miller, Miller & Steier 2004), commitment (Sharma & Irving 2005) and transformation from follower to leadership (Cater & Justis 2009). In this case, by outlining the socialisation of the successors, explanations of their motivations for joining a11d their current employment we can begin to see some of the underlying mechanisms at work motivating the next generation to join and stay in the family business.

An experimental approach to air gap optimisation for a correction-less small field diode

Aim A recent Monte Carlo based study has shown that it is possible to design a diode that measures small field output factors equivalent to that in water. This is accomplished by placing an appropriate sized air gap above the silicon chip (1) with experimental results subsequently confirming that a particular Monte Carlo design was accurate (2). The aim of this work was to test if a new correction-less diode could be designed using an entirely experimental methodology. Method: All measurements were performed on a Varian iX at a depth of 5 cm, SSD of 95 cm and field sizes of 5, 6, 8, 10, 20 and 30 mm. Firstly, the experimental transfer of kq,clin,kq,msr from a commonly used diode detector (IBA, stereotactic field diode (SFD)) to another diode detector (Sun Nuclear, unshielded diode, (EDGEe)) was tested. These results were compared to Monte Carlo calculated values of the EDGEe. Secondly, the air gap above the EDGEe silicon chip was optimised empirically. Nine different air gap “tops” were placed above the EDGEe (air depth = 0.3, 0.6, 0.9 mm; air width = 3.06, 4.59, 6.13 mm). The sensitivity of the EDGEe was plotted as a function of air gap thickness for the field sizes measured. Results: The transfer of kq,clin,kq,msr from the SFD to the EDGEe was correct to within the simulation and measurement uncertainties. The EDGEe detector can be made “correction-less” for field sizes of 5 and 6 mm, but was ∼2% from being “correction-less” at field sizes of 8 and 10 mm. Conclusion Different materials will perturb small fields in different ways. A detector is only “correction-less” if all these perturbations happen to cancel out. Designing a “correction-less” diode is a complicated process, thus it is reasonable to expect that Monte Carlo simulations should play an important role.

The use of penumbrae to define and analyse non-standard fields

Aim A new method of penumbral analysis is implemented which allows an unambiguous determination of field size and penumbra size and quality for small fields and other non-standard fields. Both source occlusion and lateral electronic disequilibrium will affect the size and shape of cross-axis profile penumbrae; each is examined in detail. Method A new method of penumbral analysis is implemented where the square of the derivative of the cross-axis profile is plotted. The resultant graph displays two peaks in the place of the two penumbrae. This allows a strong visualisation of the quality of a field penumbra, as well as a mathematically consistent method of determining field size (distance between the two peak’s maxima), and penumbra (full-widthtenth-maximum of peak). Cross-axis profiles were simulated in a water phantom at a depth of 5 cm using Monte Carlo modelling, for field sizes between 5 and 30 mm. The field size and penumbra size of each field was calculated using the method above, as well as traditional definitions set out in IEC976. The effect of source occlusion and lateral electronic disequilibrium on the penumbrae was isolated by repeating the simulations removing electron transport and using an electron spot size of 0 mm, respectively. Results All field sizes calculated using the traditional and proposed methods agreed within 0.2 mm. The penumbra size measured using the proposed method was systematically 1.8 mm larger than the traditional method at all field sizes. The size of the source had a larger effect on the size of the penumbra than did lateral electronic disequilibrium, particularly at very small field sizes. Conclusion Traditional methods of calculating field size and penumbra are proved to be mathematically adequate for small fields. However, the field size definition proposed in this study would be more robust amongst other nonstandard fields, such as flattening filter free. Source occlusion plays a bigger role than lateral electronic disequilibrium in small field penumbra size.