Omnidirectional bearing-only see-and-avoid for small aerial robots

Motivated by the growing interest in unmanned aerial system’s applications in indoor and outdoor settings and the standardisation of visual sensors as vehicle payload. This work presents a collision avoidance approach based on omnidirectional cameras that does not require the estimation of range between two platforms to resolve a collision encounter. It will achieve a minimum separation between the two vehicles involved by maximising the view-angle given by the omnidirectional sensor. Only visual information is used to achieve avoidance under a bearing-only visual servoing approach. We provide theoretical problem formulation, as well as results from real flight using small quadrotors.

Regimes and rebels

The end of the recent Communist occupation of the many countries bordering Russia marked an end to the tyranny of illegal and forced annexation. Amid these countries are my parents’ homelands, the small Baltic nations of Latvia and Estonia. Their occupation contravenes many of the numerous Articles listed by The Office of the High Commissioner for Human Rights in The Universal Declaration of Human Rights (2008), constituting many acts of violation. As a filmmaker, I was unusually incognizant of these events, despite my relationship to them. My parents never discussed the war, while during the ensuing Communist era, information was conspicuously absent. However, this lack of knowledge provided the incentive that compelled a journey of discovery that resulted in the making of Regimes and Rebels. This Masters project is presented is two parts. The film equates to 70% of the project (52 minutes in length), whilst the exegesis represents the remaining 30%. The film is a ‘human rights’, ‘video diary’ styled documentary film about the Communist occupation of my parents’ homelands, Latvia and Estonia, and the resonating effect of the occupation on our family living in Australia and family still living in the homelands. The production of the video diary is contextualised by this exegesis, which concurrently discusses the burgeoning video diary format as the basis for making a ‘human rights’ documentary film. A discussion about the latter genre of documentary film ensues, encompassing modes of representation, followed by various issues related to production including: issues of aesthetics, styles, digital media, lack of evidence and subjectivity analogous with both filmmaker and audience. Next, work by other filmmakers in the ‘human rights’ genre, linked to the proliferation of Communism in Europe, is discussed and analysed in terms of production and modes of representation. The exegesis ends with my experience as filmmaker and an analysis of factors that arose in making Regimes and Rebels.

Effects of varied ionic calcium and phosphate on the proliferation, osteogenic differentiation and mineralization of human periodontal ligament cells in vitro

Background and Objective: A number of bone filling materials containing calcium (Ca++) and phosphate (P) ions have been used in the repair of periodontal bone defects; however, the effect that local release of Ca++ and P ions have on biological reactions is not fully understood. In this study, we investigated the effects of various levels of Ca++ and P ions on the proliferation, osteogenic differentiation, and mineralization of human periodontal ligament cells (hPDLCs). Materials and Methods: hPDLCs were obtained using an explant culture method. Defined concentrations and ratios of ionic Ca++ to inorganic P were added to standard culture and osteogenic induction media. The ability of hPDLCs to proliferate in these growth media was assayed using the Cell Counting Kit-8 (CCK-8). Cell apoptosis was evaluated by FITC-Annexin V/PI double staining method. Osteogenic differentiation and mineralization were investigated by morphological observations, alkaline phosphatase (ALP) activity, and Alizarin red S/von Kossa staining. The mRNA expression of osteogenic related markers was analyzed using a reverse transcriptase polymerase chain reaction (RT-PCR). Results: Within the ranges of Ca++ and P ions concentrations tested, we observed that increased concentrations of Ca++ and P ions enhanced cell proliferation and formation of mineralized matrix nodules; whereas ALP activity was reduced. The RT-PCR results showed that elevated concentrations of Ca++ and P ions led to a general increase of Runx2 mRNA expression and decreased ALP mRNA expression, but gave no clear trend on OCN mRNA levels. Conclusion: The concentrations and ratios of Ca++ and P ions could significantly influence proliferation, differentiation, and mineralization of hPDLCs. Within the range of concentrations tested, we found that the combination of 9.0 mM Ca++ ions and 4.5 mM P ions were the optimum concentrations for proliferation, differentiation, and mineralization in hPDLCs.

A model of organizational innovation implementation effectiveness in small to medium firms

The present study aims to validate the current best-practice model of implementation effectiveness in small and mid-size businesses. Data from 135 organizations largely confirm the original model across various types of innovation. In addition, we extended this work by highlighting the importance of human resources in implementation effectiveness and the consequences of innovation effectiveness on future adoption attitudes. We found that the availability of skilled employees was positively related to implementation effectiveness. Furthermore, organizations that perceived a high level of benefits from implemented innovations were likely to have a positive attitude towards future innovation adoption. The implications of our improvements to the original model of implementation effectiveness are discussed.

Turbulence characteristics of a small subtropical estuary during and after some moderate rainfall

In natural estuaries, scalar diffusion and dispersion are driven by turbulence. In the present study, detailed turbulence measurements were conducted in a small subtropical estuary with semi-diurnal tides under neap tide conditions. Three acoustic Doppler velocimeters were installed mid-estuary at fixed locations close together. The units were sampled simultaneously and continuously at relatively high frequency for 50 h. The results illustrated the influence of tidal forcing in the small estuary, although low frequency longitudinal velocity oscillations were observed and believed to be induced by external resonance. The boundary shear stress data implied that the turbulent shear in the lower flow region was one order of magnitude larger than the boundary shear itself. The observation differed from turbulence data in a laboratory channel, but a key feature of natural estuary flow was the significant three dimensional effects associated with strong secondary currents including transverse shear events. The velocity covariances and triple correlations, as well as the backscatter intensity and covariances, were calculated for the entire field study. The covariances of the longitudinal velocity component showed some tidal trend, while the covariances of the transverse horizontal velocity component exhibited trends that reflected changes in secondary current patterns between ebb and flood tides. The triple correlation data tended to show some differences between ebb and flood tides. The acoustic backscatter intensity data were characterised by large fluctuations during the entire study, with dimensionless fluctuation intensity I0b =Ib between 0.46 and 0.54. An unusual feature of the field study was some moderate rainfall prior to and during the first part of the sampling period. Visual observations showed some surface scars and marked channels, while some mini transient fronts were observed.

Turbulent measurements in a small subtropical estuary with semidiurnal tides

Since predictions of scalar dispersion in small estuaries can rarely be predicted accurately, new field measurements were conducted continuously at relatively high frequency for up to 50 h (per investigation) in a small subtropical estuary with semidiurnal tides. The bulk flow parameters varied in time with periods comparable to tidal cycles and other large-scale processes. The turbulence properties depended upon the instantaneous local flow properties. They were little affected by the flow history, but their structure and temporal variability were influenced by a variety of parameters including the tidal conditions and bathymetry. A striking feature of the data sets was the large fluctuations in all turbulence characteristics during the tidal cycle, and basic differences between neap and spring tide turbulence.

Physical characteristics of small ions and their interaction with ultrafine particles in the urban environment

In recent years, the effect of ions and ultrafine particles on ambient air quality and human health has been well documented, however, knowledge about their sources, concentrations and interactions within different types of urban environments remains limited. This thesis presents the results of numerous field studies aimed at quantifying variations in ion concentration with distance from the source, as well as identifying the dynamics of the particle ionisation processes which lead to the formation of charged particles in the air. In order to select the most appropriate measurement instruments and locations for the studies, a literature review was also conducted on studies that reported ion and ultrafine particle emissions from different sources in a typical urban environment. The initial study involved laboratory experiments on the attachment of ions to aerosols, so as to gain a better understanding of the interaction between ions and particles. This study determined the efficiency of corona ions at charging and removing particles from the air, as a function of different particle number and ion concentrations. The results showed that particle number loss was directly proportional to particle charge concentration, and that higher small ion concentrations led to higher particle deposition rates in all size ranges investigated. Nanoparticles were also observed to decrease with increasing particle charge concentration, due to their higher Brownian mobility and subsequent attachment to charged particles. Given that corona discharge from high voltage powerlines is considered one of the major ion sources in urban areas, a detailed study was then conducted under three parallel overhead powerlines, with a steady wind blowing in a perpendicular direction to the lines. The results showed that large sections of the lines did not produce any corona at all, while strong positive emissions were observed from discrete components such as a particular set of spacers on one of the lines. Measurements were also conducted at eight upwind and downwind points perpendicular to the powerlines, spanning a total distance of about 160m. The maximum positive small and large ion concentrations, and DC electric field were observed at a point 20 m downwind from the lines, with median values of 4.4×103 cm-3, 1.3×103 cm-3 and 530 V m-1, respectively. It was estimated that, at this point, less than 7% of the total number of particles was charged. The electrical parameters decreased steadily with increasing downwind distance from the lines but remained significantly higher than background levels at the limit of the measurements. Moreover, vehicles are one of the most prevalent ion and particle emitting sources in urban environments, and therefore, experiments were also conducted behind a motor vehicle exhaust pipe and near busy motorways, with the aim of quantifying small ion and particle charge concentration, as well as their distribution as a function of distance from the source. The study found that approximately equal numbers of positive and negative ions were observed in the vehicle exhaust plume, as well as near motorways, of which heavy duty vehicles were believed to be the main contributor. In addition, cluster ion concentration was observed to decrease rapidly within the first 10-15 m from the road and ion-ion recombination and ion-aerosol attachment were the most likely cause of ion depletion, rather than dilution and turbulence related processes. In addition to the above-mentioned dominant ion sources, other sources also exist within urban environments where intensive human activities take place. In this part of the study, airborne concentrations of small ions, particles and net particle charge were measured at 32 different outdoor sites in and around Brisbane, Australia, which were classified into seven different groups as follows: park, woodland, city centre, residential, freeway, powerlines and power substation. Whilst the study confirmed that powerlines, power substations and freeways were the main ion sources in an urban environment, it also suggested that not all powerlines emitted ions, only those with discrete corona discharge points. In addition to the main ion sources, higher ion concentrations were also observed environments affected by vehicle traffic and human activities, such as the city centre and residential areas. A considerable number of ions were also observed in a woodland area and it is still unclear if they were emitted directly from the trees, or if they originated from some other local source. Overall, it was found that different types of environments had different types of ion sources, which could be classified as unipolar or bipolar particle sources, as well as ion sources that co-exist with particle sources. In general, fewer small ions were observed at sites with co-existing sources, however particle charge was often higher due to the effect of ion-particle attachment. In summary, this study quantified ion concentrations in typical urban environments, identified major charge sources in urban areas, and determined the spatial dispersion of ions as a function of distance from the source, as well as their controlling factors. The study also presented ion-aerosol attachment efficiencies under high ion concentration conditions, both in the laboratory and in real outdoor environments. The outcomes of these studies addressed the aims of this work and advanced understanding of the charge status of aerosols in the urban environment.

Identifying parent perspectives to guide active travel intervention with small populations : case study in Denver, Colorado

This paper investigates a strategy for guiding school-based active travel intervention. School-based active travel programs address the travel behaviors and perceptions of small target populations (i.e., at individual schools) so they can encourage people to walk or bike. Thus, planners need to know as much as possible about the behaviors and perceptions of their target populations. However, existing strategies for modeling travel behavior and segmenting audiences typically work with larger populations and may not capture the attitudinal diversity of smaller groups. This case study used Q technique to identify salient travel-related attitude types among parents at an elementary school in Denver, Colorado; 161 parents presented their perspectives about school travel by rank-ordering 36 statements from strongly disagree to strongly agree in a normalized distribution, single centered around no opinion. Thirty-nine respondents' cases were selected for case-wise cluster analysis in SPSS according to criteria that made them most likely to walk: proximity to school, grade, and bus service. Analysis revealed five core perspectives that were then correlated with the larger respondent pool: optimistic walkers, fair-weather walkers, drivers of necessity, determined drivers, and fence sitters. Core perspectives are presented—characterized by parents' opinions, personal characteristics, and reported travel behaviors—and recommendations are made for possible intervention approaches. The study concludes that Q technique provides a fine-grained assessment of travel behavior for small populations, which would benefit small-scale behavioral interventions

Unintended consequences of regulatory reporting requirements for small and medium size construction entities : Australian evidence

The Queensland Building Services Authority (QBSA) regulates the construction industry in Queensland, Australia, with licensing requirements creating differential financial reporting obligations, depending on firm size. Economic theories of regulation and behaviour provide a framework for investigating effects of the financial constraints and financial reporting requirements imposed by QBSA licensing. Data are analysed for all small and medium construction entities operating in Queensland between 2001 and 2006. Findings suggesting that construction licensees are categorizing themselves as smaller to avoid the more onerous and costly financial reporting of higher licensee categories are consistent with US findings from the 2002 Sarbanes-Oxley (SOX) regulation which created incentives for small firms to stay small to avoid the costs of compliance with more onerous financial reporting requirements. Such behaviour can have the undesirable economic consequences of adversely affecting employment, investment, wealth creation and financial stability. Insights and implications from the analysed QBSA processes are important for future policy reform and design, and useful to be considered where similar regulatory approaches are planned.

Models of collective cell motion for cell populations with different aspect ratio : diffusion, proliferation and travelling waves

Continuum, partial differential equation models are often used to describe the collective motion of cell populations, with various types of motility represented by the choice of diffusion coefficient, and cell proliferation captured by the source terms. Previously, the choice of diffusion coefficient has been largely arbitrary, with the decision to choose a particular linear or nonlinear form generally based on calibration arguments rather than making any physical connection with the underlying individual-level properties of the cell motility mechanism. In this work we provide a new link between individual-level models, which account for important cell properties such as varying cell shape and volume exclusion, and population-level partial differential equation models. We work in an exclusion process framework, considering aligned, elongated cells that may occupy more than one lattice site, in order to represent populations of agents with different sizes. Three different idealizations of the individual-level mechanism are proposed, and these are connected to three different partial differential equations, each with a different diffusion coefficient; one linear, one nonlinear and degenerate and one nonlinear and nondegenerate. We test the ability of these three models to predict the population level response of a cell spreading problem for both proliferative and nonproliferative cases. We also explore the potential of our models to predict long time travelling wave invasion rates and extend our results to two dimensional spreading and invasion. Our results show that each model can accurately predict density data for nonproliferative systems, but that only one does so for proliferative systems. Hence great care must be taken to predict density data for with varying cell shape.

Power relations and small and medium-sized enterprise strategies for capturing value in global production networks: visual effects (VFX) service firm in the Hollywood film industry

Power relations and small and medium-sized enterprise strategies for capturing value in global production networks: visual effects (VFX) service firms in the Hollywood film industry, Regional Studies. This paper provides insights into the way in which non-lead firms manoeuvre in global value chains in the pursuit of a larger share of revenue and how power relations affect these manoeuvres. It examines the nature of value capture and power relations in the global supply of visual effects (VFX) services and the range of strategies VFX firms adopt to capture higher value in the global value chain. The analysis is based on a total of thirty-six interviews with informants in the industry in Australia, the United Kingdom and Canada, and a database of VFX credits for 3323 visual products for 640 VFX firms.

Project-based organization as adaptation to risk and opportunity in small firms

Recent years have seen a rapid increase in SMEs working collaboratively in inter-organizational projects. But what drives the emergence of such projects, and what types of industries breed them the most? To address these questions, this paper extends the long running literature on the firm and industry antecedents of new venturing and alliance formation to the domain of project-based organization by SMEs. Based on survey data collected among 1,725 small and medium sized organizations and longitudinal industry data, we find an overall pattern that indicates that IOPV participation is primarily determined by a focal SME’s scope of innovative activities, and the munificence, dynamism and complexity of its environment. Unexpectedly, these variables have different effects on whether SMEs are likely to engage in IOPVs, compared to with how many there are in their portfolio at a time. Implications for theory development are discussed.

Separation of acoustic emission signals from small size multi-cylinder diesel engine

This paper presents techniques which can lead to diagnosis of faults in a small size multi-cylinder diesel engine. Preliminary analysis of the acoustic emission (AE) signals is outline, including time-frequency analysis and selection of optimum frequency band.The results of applying mean field independent component analysis (MFICA) to separate the AE root mean square (RMS) signals and the effects of changing parameter values are also outlined. The results on separation of RMS signals show thsi technique has the potential of increasing the probability to successfully identify the AE events associated with the various mechanical events within the combustion process of multi-cylinder diesel engines.

Trust, reputation and the small firm : building online brand reputation for SMEs

Social media provides numerous opportunities for small businesses to promote their products and services, build brand communities and reach diverse market niches. An important factor in seizing these opportunities is developing trust and creating reputation among consumers. This qualitative study examines how a group of Australian small business managers utilize social media websites to connect to, communicate with and maintain their customer base. For the purpose of this paper we are using case studies of four companies physically based in Victoria, Australia. These businesses have a high presence in online consumer groups, being both active members of communities and representatives of their businesses. The duality of their role as participant and company representative imposes difficulties in creating reputation among community members. We have used in-depth interviews as a primary research method, additionally monitoring their activities on social media sites such as forums, social networking services, blogs and micro-blogs. We have identified practices helpful for developing trust, building reputation and create a brand image in online communities.