956 resultados para flat starts
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This thesis studied the source of instability in optical phase modulators used in high accuracy laser measurement systems. The nonlinear origin of the amplitude noise helped further reducing this instability in applications that rely on phase modulators to function. This outcome will have positive impacts on the development of new methods in the amplitude noise suppression.
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This paper presents the outcome of a study that investigated the relationships between technology prior experience, self-efficacy, technology anxiety, complexity of interface (nested versus flat) and intuitive use in older people. The findings show that, as expected, older people took less time to complete the task on the interface that used a flat structure when compared to the interface that used a complex nested structure. All age groups also used the flat interface more intuitively. However, contrary to what was hypothesised, older age groups did better under anxious conditions. Interestingly, older participants did not make significantly more errors compared with younger age groups on either interface structures.
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At the time of its official opening on 15 July 2011, The University of Queensland 1.22 MW array was the largest flat-panel PhotoVoltaic (PV) array in Australia. This PV array consists of over 5000 Trina Solar 240 Wp polycrystalline silicon PV modules installed across four rooftops at the St Lucia campus. Grid connection was achieved with 85 12.5 kW three phase and four 5 kW single phase grid connect inverters manufactured by Power-One. The site also includes one 8.4 kWp SolFocus concentrating solar 2 axis tracking PV array. Site wide monitoring and data logging of all DC, AC and environmental quantities will allow this array to be a rich source of research data. The site will also include a 200 kW 400 kWh zinc bromine energy storage system by Redflow, and associated power quality metering and monitoring. This paper presents highlights of the project feasibility study which included a site survey, shading analysis, and technology and triple bottom line assessment. A detailed description of the final technical implementation including discussion of alterative options considered is given. Finally, example initial data showing yield, trends and early example experimental results are presented.
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Multilevel converters can achieve an overall effective switch frequency multiplication and consequent ripple reduction through the cancellation of the lowest order switch frequency terms. This paper investigates the harmonic content and the frequency response of these multimodulator converters. It is shown that the transfer function of uniformly sampled modulators is a bessel function associated with the inherent sampling process. Naturally sampled modulators have a flat transfer function, but multiple switchings per switch cycle will occur unless the input is slew-rate limited. Lower sideband harmonics of the effective carrier frequency and, in uniform converters, harmonics of the input signal also limit the useful bandwidth. Observations about the effect of the number of converters, their type (naturally or uniformly sampled), and the ratio of modulating frequency and switch frequency are made
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Railway is one of the most important, reliable and widely used means of transportation, carrying freight, passengers, minerals, grains, etc. Thus, research on railway tracks is extremely important for the development of railway engineering and technologies. The safe operation of a railway track is based on the railway track structure that includes rails, fasteners, pads, sleepers, ballast, subballast and formation. Sleepers are very important components of the entire structure and may be made of timber, concrete, steel or synthetic materials. Concrete sleepers were first installed around the middle of last century and currently are installed in great numbers around the world. Consequently, the design of concrete sleepers has a direct impact on the safe operation of railways. The "permissible stress" method is currently most commonly used to design sleepers. However, the permissible stress principle does not consider the ultimate strength of materials, probabilities of actual loads, and the risks associated with failure, all of which could lead to the conclusion of cost-ineffectiveness and over design of current prestressed concrete sleepers. Recently the limit states design method, which appeared in the last century and has been already applied in the design of buildings, bridges, etc, is proposed as a better method for the design of prestressed concrete sleepers. The limit states design has significant advantages compared to the permissible stress design, such as the utilisation of the full strength of the member, and a rational analysis of the probabilities related to sleeper strength and applied loads. This research aims to apply the ultimate limit states design to the prestressed concrete sleeper, namely to obtain the load factors of both static and dynamic loads for the ultimate limit states design equations. However, the sleepers in rail tracks require different safety levels for different types of tracks, which mean the different types of tracks have different load factors of limit states design equations. Therefore, the core tasks of this research are to find the load factors of the static component and dynamic component of loads on track and the strength reduction factor of the sleeper bending strength for the ultimate limit states design equations for four main types of tracks, i.e., heavy haul, freight, medium speed passenger and high speed passenger tracks. To find those factors, the multiple samples of static loads, dynamic loads and their distributions are needed. In the four types of tracks, the heavy haul track has the measured data from Braeside Line (A heavy haul line in Central Queensland), and the distributions of both static and dynamic loads can be found from these data. The other three types of tracks have no measured data from sites and the experimental data are hardly available. In order to generate the data samples and obtain their distributions, the computer based simulations were employed and assumed the wheel-track impacts as induced by different sizes of wheel flats. A valid simulation package named DTrack was firstly employed to generate the dynamic loads for the freight and medium speed passenger tracks. However, DTrack is only valid for the tracks which carry low or medium speed vehicles. Therefore, a 3-D finite element (FE) model was then established for the wheel-track impact analysis of the high speed track. This FE model has been validated by comparing its simulation results with the DTrack simulation results, and with the results from traditional theoretical calculations based on the case of heavy haul track. Furthermore, the dynamic load data of the high speed track were obtained from the FE model and the distributions of both static and dynamic loads were extracted accordingly. All derived distributions of loads were fitted by appropriate functions. Through extrapolating those distributions, the important parameters of distributions for the static load induced sleeper bending moment and the extreme wheel-rail impact force induced sleeper dynamic bending moments and finally, the load factors, were obtained. Eventually, the load factors were obtained by the limit states design calibration based on reliability analyses with the derived distributions. After that, a sensitivity analysis was performed and the reliability of the achieved limit states design equations was confirmed. It has been found that the limit states design can be effectively applied to railway concrete sleepers. This research significantly contributes to railway engineering and the track safety area. It helps to decrease the failure and risks of track structure and accidents; better determines the load range for existing sleepers in track; better rates the strength of concrete sleepers to support bigger impact and loads on railway track; increases the reliability of the concrete sleepers and hugely saves investments on railway industries. Based on this research, many other bodies of research can be promoted in the future. Firstly, it has been found that the 3-D FE model is suitable for the study of track loadings and track structure vibrations. Secondly, the equations for serviceability and damageability limit states can be developed based on the concepts of limit states design equations of concrete sleepers obtained in this research, which are for the ultimate limit states.
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Our results demonstrate that photorefractive residual amplitude modulation (RAM) noise in electro-optic modulators (EOMs) can be reduced by modifying the incident beam intensity distribution. Here we report an order of magnitude reduction in RAM when beams with uniform intensity (flat-top) profiles, generated with an LCOS-SLM, are used instead of the usual fundamental Gaussian mode (TEM00). RAM arises from the photorefractive amplified scatter noise off the defects and impurities within the crystal. A reduction in RAM is observed with increasing intensity uniformity (flatness), which is attributed to a reduction in space charge field on the beam axis. The level of RAM reduction that can be achieved is physically limited by clipping at EOM apertures, with the observed results agreeing well with a simple model. These results are particularly important in applications where the reduction of residual amplitude modulation to 10^-6 is essential.
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In this paper we explore the relationship between monthly random breath testing (RBT) rates (per 1000 licensed drivers) and alcohol-related traffic crash (ARTC) rates over time, across two Australian states: Queensland and Western Australia. We analyse the RBT, ARTC and licensed driver rates across 12 years; however, due to administrative restrictions, we model ARTC rates against RBT rates for the period July 2004 to June 2009. The Queensland data reveals that the monthly ARTC rate is almost flat over the five year period. Based on the results of the analysis, an average of 5.5 ARTCs per 100,000 licensed drivers are observed across the study period. For the same period, the monthly rate of RBTs per 1000 licensed drivers is observed to be decreasing across the study with the results of the analysis revealing no significant variations in the data. The comparison between Western Australia and Queensland shows that Queensland's ARTC monthly percent change (MPC) is 0.014 compared to the MPC of 0.47 for Western Australia. While Queensland maintains a relatively flat ARTC rate, the ARTC rate in Western Australia is increasing. Our analysis reveals an inverse relationship between ARTC RBT rates, that for every 10% increase in the percentage of RBTs to licensed driver there is a 0.15 decrease in the rate of ARTCs per 100,000 licenced drivers. Moreover, in Western Australia, if the 2011 ratio of 1:2 (RBTs to annual number of licensed drivers) were to double to a ratio of 1:1, we estimate the number of monthly ARTCs would reduce by approximately 15. Based on these findings we believe that as the number of RBTs conducted increases the number of drivers willing to risk being detected for drinking driving decreases, because the perceived risk of being detected is considered greater. This is turn results in the number of ARTCs diminishing. The results of this study provide an important evidence base for policy decisions for RBT operations.
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Indium tin-oxide (ITO) and polycrystalline boron-doped diamond (BDD) have been examined in detail using the scanning electrochemical microscopy technique in feedback mode. For the interrogation of electrodes made from these materials, the choice of mediator has been varied. Using Ru(CN) 4− 6 (aq), ferrocene methanol (FcMeOH), Fe(CN) 3− 6 (aq) and Ru(NH 3) 3+ 6 (aq), approach curve experiments have been performed, and for purposes of comparison, calculations of the apparent heterogeneous electron transfer rates (k app) have been made using these data. In general, it would appear that values of k app are affected mainly by the position of the mediator reversible potential relative to the relevant semiconductor band edge (associated with majority carriers). For both the ITO (n type) and BDD (p type) electrodes, charge transfer is impeded and values are very low when using FcMeOH and Fe(CN) 3− 6 (aq) as mediators, and the use of Ru(NH 3) 3+ 6(aq) results in the largest value of k app. With ITO, the surface is chemically homogeneous and no variation is observed for any given mediator. Data is also presented where the potential of the ITO electrode is fixed using a ratio of the mediators Fe(CN) 3− 6(aq) and Fe(CN) 4− 6(aq). In stark contrast, the BDD electrode is quite the opposite and a range of k app values are observed for all mediators depending on the position on the surface. Both electrode surfaces are very flat and very smooth, and hence, for BDD, variations in feedback current imply a variation in the electrochemical activity. A comparison of the feedback current where the substrate is biased and unbiased shows a surprising degree of proportionality.
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Liquid metal marbles that are droplets of liquid metal encapsulated by micro- or nanoparticles are introduced. Droplets of galinstan liquid metal are coated with insulators (including Teflon and silica) and semiconductors (including WO3, TiO2, MoO3, In2O3 and carbon nanotubes) by rolling over a powder bed and also by submerging in colloidal suspensions. It is shown that these marbles can be split and merged, can be suspended on water, and are even stable when moving under the force of gravity and impacting a flat solid surface. Furthermore, the marble coating can operate as an active electronic junction and the nanomaterial coated liquid metal marble can act as a highly sensitive electrochemical based heavy metal ion sensor. This new element thus represents a significant platform for the advancement of research into soft electronics.
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The complex [1,2-bis(di-tert-butylphosphanyl)ethane-[kappa]2P,P']diiodidonickel(II), [NiI2(C18H40P2] or (dtbpe-[kappa]2P)NiI2, [dtbpe is 1,2-bis(di-tert-butylphosphanyl)ethane], is bright blue-green in the solid state and in solution, but, contrary to the structure predicted for a blue or green nickel(II) bis(phosphine) complex, it is found to be close to square planar in the solid state. The solution structure is deduced to be similar, because the optical spectra measured in solution and in the solid state contain similar absorptions. In solution at room temperature, no 31P{1H} NMR resonance is observed, but the very small solid-state magnetic moment at temperatures down to 4 K indicates that the weak paramagnetism of this nickel(II) complex can be ascribed to temperature independent paramagnetism, and that the complex has no unpaired electrons. The red [1,2-bis(di-tert-butylphosphanyl)ethane-[kappa]2P,P']dichloridonickel(II), [NiCl2(C18H40P2] or (dtbpe-[kappa]2P)NiCl2, is very close to square planar and very weakly paramagnetic in the solid state and in solution, while the maroon [1,2-bis(di-tert-butylphosphanyl)ethane-[kappa]2P,P']dibromidonickel(II), [NiBr2(C18H40P2] or (dtbpe-[kappa]2P)NiBr2, is isostructural with the diiodide in the solid state, and displays paramagnetism intermediate between that of the dichloride and the diiodide in the solid state and in solution. Density functional calculations demonstrate that distortion from an ideal square plane for these complexes occurs on a flat potential energy surface. The calculations reproduce the observed structures and colours, and explain the trends observed for these and similar complexes. Although theoretical investigation identified magnetic-dipole-allowed excitations that are characteristic for temperature-independent paramagnetism (TIP), theory predicts the molecules to be diamagnetic.
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The international climate regime is in the process of negotiating a legally binding instrument concerning Reducing Emissions from Deforestation and Degradation (REDD+). The paper starts by exploring the complex web of decisions and advices that currently regulate REDD+ initiatives within the international climate regime. This is followed by an analysis of justice issues raised by non-state actors in the REDD+ international negotiations. The paper concludes by building on this analysis to identify some relevant considerations when seeking to design a just and legally binding REDD+ instrument. These considerations include: the impact of market- versus fund-based investment channels, the importance of defining a clear objective; the inclusion and role of international principles such as sovereignty, preventative action, common but differentiated responsibility, sustainable development, and Free, Prior, and Informed Consent; the appropriate design of REDD+ safeguards and the inclusion of grievance mechanisms within the instrument which provide guidance on resolving disputes associated with REDD+ investment.
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Orchids: My Intersex Adventure is a multi-award winning autobiographical documentary film. The film follows documentary filmmaker, Phoebe Hart, as she comes clean on her journey of self-discovery to embrace her future and reconcile the past shame and family secrecy surrounding her intersex condition. Despite her mother’s outright refusal to be in the film, Phoebe decides she must push on with her quest to resolve her life story and connect with other intersex people on camera. With the help of her sister Bonnie and support from her partner James, she hits the open road and reflects on her youth. Phoebe’s happy and carefree childhood came to an abrupt end at puberty when she was told she would never menstruate nor have children. But the reasons why were never discussed and the topic was taboo. At the age of 17, Phoebe’s mother felt she was old enough to understand the true nature of her body and the family secret was finally revealed. Phoebe then faced an orchidectomy, invasive surgery to remove her undescended testes, the emotional scars of which are still raw today. Phoebe’s road trip around Australia exposes her to the stories of other intersex people and holds a mirror to her own experience. She learns valuable lessons in resilience and healing but also sees the pervasive impact her condition has on all her relationships. At home, Phoebe and James want to start a family but dealing with infertility and the stress of the adoption process puts pressure on their marriage. Phoebe also starts to understand the difficult decisions her parents faced and is excited but apprehensive when they eventually agree to be interviewed. Will talking openly with her mother give Phoebe the answers she has been looking for? The film was produced and directed by Phoebe Hart and commissioned by the Australian Broadcasting Commission. The film premiered at the Brisbane International Film Festival in 2010 where it was voted the number one film of the festival by audiences. Orchids was broadcast on ABC1 in Australia in 2012, appeared in more than 50 film festivals internationally and has since been broadcast nationally in Switzerland, Sweden, Israel, Spain, France, Russia, Poland, Germany and the USA.
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A recent success story of the Australian videogames industry is Brisbane based Halfbrick Studios, developer of the hit game for mobile devices, Fruit Ninja. Halfbrick not only survived the global financial crisis and an associated downturn in the Australian industry, but grew strongly, moving rapidly from developing licensed properties for platforms such as Game Boy Advance, Nintendo DS, and Playstation Portable (PSP) to becoming an independent developer and publisher of in-house titles, generating revenue both through App downloads and merchandise sales. Amongst the reasons for Halfbrick’s success is their ability to adaptively transform by addressing different technical platforms, user dynamics, business models and market conditions. Our ongoing case-study research from 2010 into Halfbrick’s innovation processes, culminating with some 10 semi-structured interviews with senior managers and developers, has identified a strong focus on workplace organisational culture, with staff reflecting that the company is a flat, team-based organisation devolving as much control as possible to the development teams directly, and encouraging a work-life balance in which creativity can thrive. The success of this strategy is evidenced through Halfbrick’s low staff turnover; amongst our interviewees most of the developers had been with the company for a number of years, with all speaking positively of the workplace culture and sense of creative autonomy they enjoyed. Interviews with the CEO, Shainiel Deo, and team leaders highlighted the autonomy afforded to each team and the organisation and management of the projects on which they work. Deo and team leaders emphasised the collaboration and communication skills they require in the developers that they employ, and that these characteristics were considered just as significant in hiring decisions as technical skills. Halfbrick’s developers celebrate their workplace culture and insist it has contributed to their capacity for innovation and to their commercial success with titles such as Fruit Ninja. This model of organisational management is reflected in both Stark’s (2009) idea of heterarchy, and Neff’s (2012) concept of venture labour, and provides a different perspective on the industry than the traditional political economy critique of precarious labour exploited by gaming conglomerates. Nevertheless, throughout many of the interviews and in our informal discussions with Halfbrick developers there is also a sense that this rewarding culture is quite tenuous and precarious in the context of a rapidly changing and uncertain global videogames industry. Whether such a workplace culture represents the future of the games industry, or is merely a ‘Prague Spring’ before companies such as Halfbrick are swallowed by traditional players’ remains to be seen. However, as the process of rapid and uncertain transformation plays out across the videogames industry, it is important to pay attention to emerging modes of organisation and workplace culture, even whilst they remain at the margins of the industry. In this paper we investigate Halfbrick’s workplace culture and ask how sustainable is this kind of rewarding and creative workplace?
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BACKGROUND: Variations in 'slope' (how steep or flat the ground is) may be good for health. As walking up hills is a physiologically vigorous physical activity and can contribute to weight control, greater neighbourhood slopes may provide a protective barrier to weight gain, and help prevent Type 2 diabetes onset. We explored whether living in 'hilly' neighbourhoods was associated with diabetes prevalence among the Australian adult population. METHODS: Participants ([greater than or equal to]25years; n=11,406) who completed the Western Australian Health and Wellbeing Surveillance System Survey (2003-2009) were asked whether or not they had medically-diagnosed diabetes. Geographic Information Systems (GIS) software was used to calculate a neighbourhood mean slope score, and other built environment measures at 1600m around each participant's home. Logistic regression models were used to predict the odds of self-reported diabetes after progressive adjustment for individual measures (i.e., age, sex), socioeconomic status (i.e., education, income), built environment, destinations, nutrition, and amount of walking. RESULTS: After full adjustment, the odds of self-reported diabetes was 0.72 (95% CI 0.55-0.95) and 0.52 (95% CI 0.39-0.69) for adults living in neighbourhoods with moderate and higher levels of slope, respectively, compared with adults living in neighbourhoods with the lowest levels of slope. The odds of having diabetes was 13% lower (odds ratio 0.87; 95% CI 0.80-0.94) for each increase of one percent in mean slope. CONCLUSIONS: Living in a hilly neighbourhood may be protective of diabetes onset or this finding is spurious. Nevertheless, the results are promising and have implications for future research and the practice of flattening land in new housing developments.
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The Lady Elliot Island eco-resort, on the Great Barrier Reef, operates with a strong sustainability ethic, and has broken away from its reliance on diesel generators, an initiative which has ongoing and substantial economic benefit. The first step was an energy audit that led to a 35% reduction in energy usage, to an average of 575 kWh per day. The eco-resort then commissioned a hybrid solar power station, in 2008, with energy storage in battery banks. Solar power is currently (2013) providing about 160 kWh of energy per day, and the eco-resort’s diesel fuel usage has decreased from 550 to 100 litres per day, enabling the power station to pay for itself in 3 years. The eco-resort plans to complete its transition to renewable energy by 2015, by installing additional solar panels, and a 10-15 kW wind turbine. This paper starts by discussing why the eco-resort chose a hybrid solar power station to transition to renewable energy, and the barriers to change. It then describes the power station, upgrades through to 2013, the power control system, the problems that were solved to realise the potential of a facility operating in a harsh and remote environment, and its performance. The paper concludes by outlining other eco-resort sustainability practices, including education and knowledge-sharing initiatives, and monitoring the island’s environmental and ecological condition.