Unit commitment in power systems with plug-in hybrid electric vehicles

With the continued development of renewable energy generation technologies and increasing pressure to combat the global effects of greenhouse warming, plug-in hybrid electric vehicles (PHEVs) have received worldwide attention, finding applications in North America and Europe. When a large number of PHEVs are introduced into a power system, there will be extensive impacts on power system planning and operation, as well as on electricity market development. It is therefore necessary to properly control PHEV charging and discharging behaviors. Given this background, a new unit commitment model and its solution method that takes into account the optimal PHEV charging and discharging controls is presented in this paper. A 10-unit and 24-hour unit commitment (UC) problem is employed to demonstrate the feasibility and efficiency of the developed method, and the impacts of the wide applications of PHEVs on the operating costs and the emission of the power system are studied. Case studies are also carried out to investigate the impacts of different PHEV penetration levels and different PHEV charging modes on the results of the UC problem. A 100-unit system is employed for further analysis on the impacts of PHEVs on the UC problem in a larger system application. Simulation results demonstrate that the employment of optimized PHEV charging and discharging modes is very helpful for smoothing the load curve profile and enhancing the ability of the power system to accommodate more PHEVs. Furthermore, an optimal Vehicle to Grid (V2G) discharging control provides economic and efficient backups and spinning reserves for the secure and economic operation of the power system

Decision support for the safe design and operation of unmanned aircraft systems

Unmanned Aircraft Systems (UAS) describe a diverse range of aircraft that are operated without a human pilot on-board. Unmanned aircraft range from small rotorcraft, which can fit in the palm of your hand, through to fixed wing aircraft comparable in size to that of a commercial passenger jet. The absence of a pilot on-board allows these aircraft to be developed with unique performance capabilities facilitating a wide range of applications in surveillance, environmental management, agriculture, defence, and search and rescue. However, regulations relating to the safe design and operation of UAS first need to be developed before the many potential benefits from these applications can be realised. According to the International Civil Aviation Organization (ICAO), a Risk Management Process (RMP) should support all civil aviation policy and rulemaking activities (ICAO 2009). The RMP is described in International standard, ISO 31000:2009 (ISO, 2009a). This standard is intentionally generic and high-level, providing limited guidance on how it can be effectively applied to complex socio-technical decision problems such as the development of regulations for UAS. Through the application of principles and tools drawn from systems philosophy and systems engineering, this thesis explores how the RMP can be effectively applied to support the development of safety regulations for UAS. A sound systems-theoretic foundation for the RMP is presented in this thesis. Using the case-study scenario of a UAS operation over an inhabited area and through the novel application of principles drawn from general systems modelling philosophy, a consolidated framework of the definitions of the concepts of: safe, risk and hazard is made. The framework is novel in that it facilitates the representation of broader subjective factors in an assessment of the safety of a system; describes the issues associated with the specification of a system-boundary; makes explicit the hierarchical nature of the relationship between the concepts and the subsequent constraints that exist between them; and can be evaluated using a range of analytic or deliberative modelling techniques. Following the general sequence of the RMP, the thesis explores the issues associated with the quantified specification of safety criteria for UAS. A novel risk analysis tool is presented. In contrast to existing risk tools, the analysis tool presented in this thesis quantifiably characterises both the societal and individual risk of UAS operations as a function of the flight path of the aircraft. A novel structuring of the risk evaluation and risk treatment decision processes is then proposed. The structuring is achieved through the application of the Decision Support Problem Technique; a modelling approach that has been previously used to effectively model complex engineering design processes and to support decision-making in relation to airspace design. The final contribution made by this thesis is in the development of an airworthiness regulatory framework for civil UAS. A novel "airworthiness certification matrix" is proposed as a basis for the definition of UAS "Part 21" regulations. The outcome airworthiness certification matrix provides a flexible, systematic and justifiable method for promulgating airworthiness regulations for UAS. In addition, an approach for deriving "Part 1309" regulations for UAS is presented. In contrast to existing approaches, the approach presented in this thesis facilitates a traceable and objective tailoring of system-level reliability requirements across the diverse range of UAS operations. The significance of the research contained in this thesis is clearly demonstrated by its practical real world outcomes. Industry regulatory development groups and the Civil Aviation Safety Authority have endorsed the proposed airworthiness certification matrix. The risk models have also been used to support research undertaken by the Australian Department of Defence. Ultimately, it is hoped that the outcomes from this research will play a significant part in the shaping of regulations for civil UAS, here in Australia and around the world.

Prediction of pull-out force of multi-walled carbon nanotube (MWCNT) in sword-in-sheath mode

The pull-out force of some outer walls against other inner walls in multi-walled carbon nanotubes (MWCNTs) was systematically studied by molecular mechanics simulations. The obtained results reveal that the pull-out force is proportional to the square of the diameter of the immediate outer wall on the sliding interface, which highlights the primary contribution of the capped section of MWCNT to the pull-out force. A simple empirical formula was proposed based on the numerical results to predict the pull-out force for an arbitrary pull-out in a given MWCNT directly from the diameter of the immediate outer wall on the sliding interface. Moreover, tensile tests for MWCNTs with and without acid-treatment were performed with a nanomanipulator inside a vacuum chamber of a scanning electron microscope (SEM) to validate the present empirical formula. It was found that the theoretical pull-out forces agree with the present and some previous experimental results very well.

Differential effects of ERP systems on user outcomes : a longitudinal investigation

Adopting a model of job enrichment we report on a longitudinal case investigating the perceived impact of an Enterprise Resource Planning (ERP) system on user job design characteristics. Our results indicated that in the context of an ERP geared towards centralisation and standardisation the extent to which users perceived an increase or decrease in job enrichment was associated with aspects such as formal authority and the nature of their work role. Experienced operational employees proficient in the original legacy system perceived ERP system protocols to constrain their actions, limit training and increase dependence on others in the workflow. Conversely, managerial users reported a number of benefits relating to report availability, improved organisational transparency and increased overall job enrichment. These results supported our argument concerning the relationship between ERPs with a standardisation intent and positive job enrichment outcomes for managerial users and negative job-related outcomes for operational users.

Coupling of energy from quantum emitters to the plasmonic mode of V groove waveguides: A numerical study

This work is a theoretical investigation into the coupling of a single excited quantum emitter to the plasmon mode of a V groove waveguide. The V groove waveguide consists of a triangular channel milled in gold and the emitter is modeled as a dipole emitter, and could represent a quantum dot, nitrogen vacancy in diamond, or similar. In this work the dependence of coupling efficiency of emitter to plasmon mode is determined for various geometrical parameters of the emitter-waveguide system. Using the finite element method, the effect on coupling efficiency of the emitter position and orientation, groove angle, groove depth, and tip radius, is studied in detail. We demonstrate that all parameters, with the exception of groove depth, have a significant impact on the attainable coupling efficiency. Understanding the effect of various geometrical parameters on the coupling between emitters and the plasmonic mode of the waveguide is essential for the design and optimization of quantum dot–V groove devices.

Parenting satisfaction and self-efficacy : a longitudinal study of mothers of children with Down Syndrome

Continuities and changes in parenting sense of competence were examined for mothers of children with Down syndrome from early childhood to adolescence. The sample comprised 25 mothers whose child with Down syndrome was aged 4-6 years in the first phase of the study, and 11-15 years at the second time point. Maternal satisfaction with parenting increased over time, but there were no changes in parenting self-efficacy. Scores on these measures were no different from those reported in a normative sample of mothers of typically developing children, suggesting that the challenges of parenting a child with Down syndrome do not impact significantly on parenting sense of competence during the early childhood and adolescent periods. There were some significant relationships of maternal sense of competence with child characteristics and self-reported parenting style, mostly in the expected direction.

Design and fabrication of tubular scaffolds via direct writing in a melt electrospinning mode

Flexible tubular structures fabricated from solution electrospun fibers are finding increasing use in tissue engineering applications. However it is difficult to control the deposition of fibers due to the chaotic nature of the solution electrospinning jet. By using non-conductive polymer melts instead of polymer solutions the path and collection of the fiber becomes predictable. In this work we demonstrate the melt electrospinning of polycaprolactone in a direct writing mode onto a rotating cylinder. This allows the design and fabrication of tubes using 20 μm diameter fibers with controllable micropatterns and mechanical properties. A key design parameter is the fiber winding angle, where it allows control over scaffold pore morphology (e.g. size, shape, number and porosity). Furthermore, the establishment of a finite element model as a predictive design tool is validated against mechanical testing results of melt electrospun tubes to show that a lesser winding angle provides improved mechanical response to uniaxial tension and compression. In addition, we show that melt electrospun tubes support the growth of three different cell types in vitro and are therefore promising scaffolds for tissue engineering applications.

Four years on – are the Gazelles still running? A longitudinal study of firm performance after a period of rapid growth

Gazelles, or very rapidly growing firms, are important because they contribute disproportionately to economic growth. There is a concern that some of these firms pursue growth too aggressively resulting in lower subsequent performance. We investigate the relationship between growth and subsequent profitability for gazelle firms, and how this is moderated by firm strategy. Previous empirical research regarding the growth-profitability relationship for firms in general is rather inconclusive, with only one study specifically investigating gazelle firms. Likewise, there are theoretical arguments both for and against growth leading to profitability that equally apply to gazelle firms. Further, while contingency theory might suggest the relationship depends on the firm’s strategy, earlier studies have not investigated this relationship. We address these questions using longitudinal data (seven years) for a sample of 964 Danish Gazelle firms. Our study finds a clear positive relationship between growth and subsequent profitability among gazelle firms. Moreover, this relationship is stronger for firms pursuing a broad market strategy rather than a focus or niche strategy. An important managerial implication is that the growth strategy should be clearly integrated with the general strategic orientation of the firm.

A controlled, longitudinal study of home visits compared to telephone contacts to prevent early childhood caries

Background Home visits (HV) provide excellent opportunities for health promotion. Aim This longitudinal study compared the effects of HV and telephone contacts (TC) in preventing early childhood caries (ECC) and colonisation of mutans streptococci (MS) and lactobacilli (LB) from 0 to 24 months. Design A total of 325 children were recruited from community health centres at mean age of 42 days, and randomly assigned to receive either HV or TC. A total of 188 children completed three, 6 monthly HV, and another 58 had three, 6 monthly TC. An additional 40 age-matched children from childcare facilities served as reference controls (RC). At 24 months, all groups were examined at a community dental clinic. Results At 24 months, three HV children of 188 (1.5%) had caries, compared to four TC of 58 (6.8%) and nine RC of 40 (22.5%) (P < 0.001 for HV versus RC; P = 0.05 for HV versus TC and P = 0.03 for TC versus RC). There were also more children with MS in the TC (47%) and RC (35%) compared to HV (28%) group (P = 0.01 and P = 0.02). Conclusions Home visits and telephone contacts conducted 6 monthly from birth are effective in reducing ECC prevalence by 24 months.

The moderating role of learning on competitive advantage : longitudinal evidence from young firms

The question of how young firms reconcile the absence of well-established learning routines arising from the “liabilities of newness” with the “learning advantages of newness” has received scant attention in entrepreneurship. While older firms follow established learning routines and sometimes face problems in overcoming inertia, young firms with lower levels of inertia are better poised to explore, search and test unique avenues for their products and services. The process of learning and capability development as well as establishing uniqueness in their product offerings is an important part not only in the early stages of firm growth, but also in firm survival. Given their inexperience, for young firms, these learning processes are iterative and include contrasting learning loops that sometimes progress and at other times digress from initially perceived unique ideas. Such processes are embedded within capabilities that the firm develops and nurtures. Based on this premise and adopting a capabilities-based view, we examine how strategic networks and environmental knowledge affects uniqueness- mediated performance in young firms. We identify firms with digressive learning strategies based on their self-assessment of learning and compare them with other firms to demonstrate a differential effect on performance.

Could BFFB mode breath aerosol play a role in H5N1 transmission?

Recent findings concerning exhaled aerosol size distributions and the regions in the respiratory tract in which they are generated could have significant implications for human to human spread of lower respiratory tract-specific infections. Even in healthy people, measurable quantities of aerosol are routinely generated from the Lower Respiratory Tract (LRT) during breathing(1-3). We have found that there at least three modes in the exhaled aerosol size distribution of healthy adults(4) (see Figure 1). These modes each have a characteristic size and arise from different parts of the respiratory tract. The respiratory bronchioles produce aerosol during breathing, the larynx during speech and the oral cavity also during speech. The model of the resulting droplet size distribution is therefore called the Bronchial Laryngeal Oral (B.L.O.) tri-modal model of expired aerosol.

Pregnancy losses in young Australian women : findings from the Australian Longitudinal Study on Women's Health

INTRODUCTION: Little research has examined recognized pregnancy losses in a general population. Data from an Australian cohort study provide an opportunity to quantify this aspect of fecundity at a population level. METHOD: Participants in the Australian Longitudinal Study on Women's Health who were aged 28-33 years in 2006 (n = 9,145) completed up to 4 mailed surveys over 10 years. Participants were categorized according to the recognized outcome of their pregnancies, including live birth, miscarriage/stillbirth, termination/ectopic, or no pregnancy. RESULTS: At age 18-23, more women reported terminations (7%) than miscarriages (4%). By 28-33 years, the cumulative frequency of miscarriage (15%) was as common as termination (16%). For women aged 28-33 years who had ever been pregnant (n = 5,343), pregnancy outcomes were as follows: birth only (50%); loss only (18%); and birth and loss (32%), of which half (16%) were birth and miscarriage. A comparison between first miscarriage and first birth (no miscarriage) showed that most first miscarriages occurred in women aged 18-23 years who also reported a first birth at the same survey (15%). Half (51%) of all first births and first miscarriages in women aged 18-19 ended in miscarriage. Early childbearers (<28 years) often had miscarriages around the same time period as their first live birth, suggesting proactive family formation. Delayed childbearers (32-33 years) had more first births than first miscarriages. CONCLUSION: Recognized pregnancy losses are an important measure of fecundity in the general population because they indicate successful conception and maintenance of pregnancy to varying reproductive endpoints.