974 resultados para Problems increased


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Eigen-based techniques and other monolithic approaches to face recognition have long been a cornerstone in the face recognition community due to the high dimensionality of face images. Eigen-face techniques provide minimal reconstruction error and limit high-frequency content while linear discriminant-based techniques (fisher-faces) allow the construction of subspaces which preserve discriminatory information. This paper presents a frequency decomposition approach for improved face recognition performance utilising three well-known techniques: Wavelets; Gabor / Log-Gabor; and the Discrete Cosine Transform. Experimentation illustrates that frequency domain partitioning prior to dimensionality reduction increases the information available for classification and greatly increases face recognition performance for both eigen-face and fisher-face approaches.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Research in structural dynamics has received considerable attention due to problems associated with emerging slender structures, increased vulnerability of structures to random loads and aging infrastructure. This paper briefly describes some such research carried out on i) dynamics of composite floor structure, ii) dynamics of cable supported footbridge, iii) seismic mitigation of frame-shear wall structure using passive dampers and iv) development of a damage assessment model for use in structural health modelling.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Complex surveillance problems are common in biosecurity, such as prioritizing detection among multiple invasive species, specifying risk over a heterogeneous landscape, combining multiple sources of surveillance data, designing for specified power to detect, resource management, and collateral effects on the environment. Moreover, when designing for multiple target species, inherent biological differences among species result in different ecological models underpinning the individual surveillance systems for each. Species are likely to have different habitat requirements, different introduction mechanisms and locations, require different methods of detection, have different levels of detectability, and vary in rates of movement and spread. Often there is a further challenge of a lack of knowledge, literature, or data, for any number of the above problems. Even so, governments and industry need to proceed with surveillance programs which aim to detect incursions in order to meet environmental, social and political requirements. We present an approach taken to meet these challenges in one comprehensive and statistically powerful surveillance design for non-indigenous terrestrial vertebrates on Barrow Island, a high conservation nature reserve off the Western Australian coast. Here, the possibility of incursions is increased due to construction and expanding industry on the island. The design, which includes mammals, amphibians and reptiles, provides a complete surveillance program for most potential terrestrial vertebrate invaders. Individual surveillance systems were developed for various potential invaders, and then integrated into an overall surveillance system which meets the above challenges using a statistical model and expert elicitation. We discuss the ecological basis for the design, the flexibility of the surveillance scheme, how it meets the above challenges, design limitations, and how it can be updated as data are collected as a basis for adaptive management.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Intelligible and accurate risk-based decision-making requires a complex balance of information from different sources, appropriate statistical analysis of this information and consequent intelligent inference and decisions made on the basis of these analyses. Importantly, this requires an explicit acknowledgement of uncertainty in the inputs and outputs of the statistical model. The aim of this paper is to progress a discussion of these issues in the context of several motivating problems related to the wider scope of agricultural production. These problems include biosecurity surveillance design, pest incursion, environmental monitoring and import risk assessment. The information to be integrated includes observational and experimental data, remotely sensed data and expert information. We describe our efforts in addressing these problems using Bayesian models and Bayesian networks. These approaches provide a coherent and transparent framework for modelling complex systems, combining the different information sources, and allowing for uncertainty in inputs and outputs. While the theory underlying Bayesian modelling has a long and well established history, its application is only now becoming more possible for complex problems, due to increased availability of methodological and computational tools. Of course, there are still hurdles and constraints, which we also address through sharing our endeavours and experiences.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background: Pregnant women exposed to traffic pollution have an increased risk of negative birth outcomes. We aimed to investigate the size of this risk using a prospective cohort of 970 mothers and newborns in Logan, Queensland. ----- ----- Methods: We examined two measures of traffic: distance to nearest road and number of roads around the home. To examine the effect of distance we used the number of roads around the home in radii from 50 to 500 metres. We examined three road types: freeways, highways and main roads.----- ----- Results: There were no associations with distance to road. A greater number of freeways and main roads around the home were associated with a shorter gestation time. There were no negative impacts on birth weight, birth length or head circumference after adjusting for gestation. The negative effects on gestation were largely due to main roads within 400 metres of the home. For every 10 extra main roads within 400 metres of the home, gestation time was reduced by 1.1% (95% CI: -1.7, -0.5; p-value = 0.001).----- ----- Conclusions: Our results add weight to the association between exposure to traffic and reduced gestation time. This effect may be due to the chemical toxins in traffic pollutants, or because of disturbed sleep due to traffic noise.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

It could be said that road congestion is one of the most significant problems within any modern metropolitan area. For several decades now, around the globe, congestion in metropolitan areas has been worsening for two main reasons. Firstly, road congestion has significantly increased due to a higher demand for road space because of growth in populations, economic activity and incomes (Hensher & Puckett, 2007). This factor, in conjunction with a significant lack of investment in new road and public transport infrastructure, has seen the road network capacities of cities exceeded by traffic volumes and thus, resulted in increased traffic congestion. This relentless increase in road traffic congestion has resulted in a dramatic increase in costs for both the road users and ultimately the metropolitan areas concerned (Bureau of Transport and Regional Economics, 2007). In response to this issue, several major cities around the world, including London, Stockholm and Singapore, have implemented congestion-charging schemes in order to combat the effects of road congestion. A congestion-charging scheme provides a mechanism for regulating traffic flows into the congested areas of a city, whilst simultaneously generating public revenue that can be used to improve both the public transport and road networks of the region. The aim of this paper was to assess the concept of congestion-charging, whilst reflecting on the experiences of various cities that have already implemented such systems. The findings from this paper have been used to inform the design of a congestion-charging scheme for the city of Brisbane in Australia in a supplementary study (Whitehead, Bunker, & Chung, 2011). The first section of this paper examines the background to road congestion; the theory behind different congestion-charging schemes; and the various technologies involved with the concept. The second section of this paper details the experiences, in relation to implementing a congestion-charging scheme, from the city of Stockholm in Sweden. This research has been crucial in forming a list of recommendations and lessons learnt for the design of a congestion-charging scheme in Australia. It is these recommendations that directly inform the proposed design of the Brisbane Cordon Scheme detailed in Whitehead et al. (2011).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND. Physical symptoms are common in pregnancy and are predominantly associated with normal physiological changes. These symptoms have a social and economic cost, leading to absenteeism from work and additional medical interventions. There is currently no simple method for identifying common pregnancy related problems in the antenatal period. A validated tool, for use by pregnancy care providers would be useful. AIM: The aim of the project was to develop and validate a Pregnancy Symptoms Inventory for use by healthcare professionals (HCPs). METHODS: A list of symptoms was generated via expert consultation with midwives and obstetrician gynaecologists. Focus groups were conducted with pregnant women in their first, second or third trimester. The inventory was then tested for face validity and piloted for readability and comprehension. For test-re-test reliability, it was administered to the same women 2 to 3 days apart. Finally, outpatient midwives trialled the inventory for 1 month and rated its usefulness on a 10cm visual analogue scale (VAS). The number of referrals to other health care professionals was recorded during this month. RESULTS: Expert consultation and focus group discussions led to the generation of a 41-item inventory. Following face validity and readability testing, several items were modified. Individual item test re-test reliability was between .51 to 1 with the majority (34 items) scoring .0.70. During the testing phase, 211 surveys were collected in the 1 month trial. Tiredness (45.5%), poor sleep (27.5%) back pain (19.5%) and nausea (12.6%) were experienced often. Among the women surveyed, 16.2% claimed to sometimes or often be incontinent. Referrals to the incontinence nurse increased > 8 fold during the study period. The median rating by midwives of the ‘usefulness’ of the inventory was 8.4 (range 0.9 to 10). CONCLUSIONS: The Pregnancy Symptoms Inventory (PSI) was well accepted by women in the 1 month trial and may be a useful tool for pregnancy care providers and aids clinicians in early detection and subsequent treatment of symptoms. It shows promise for use in the research community for assessing the impact of lifestyle intervention in pregnancy.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

One of our most pressing needs in creating a more sustainable world is the explicit development of holistic policy. This is becoming increasingly apparent as we are faced with more and more ‘wicked problems', the most difficult class of problems that we can conceptualize. Such problems consist of ‘clusters’ of problems, and include socio-political and moral-spiritual issues. This paper articulates a methodology that can be applied to the analysis and design of underlying organizational structures and processes that will consistently and effectively address wicked problems while being consistent with the advocated 'learning by doing' approach to change management and policy making. This transdisciplinary methodology—known as the institutionalist policymaking framework—has been developed from the perspective of institutional economics synthesized with perspectives from ecological economics and system dynamics. In particular it draws on the work first presented in Hayden’s 1993 paper ‘Institutionalist Policymaking’—and further developed in his 2006 book, at the heart of which lies the SFM—and the applicability of this approach in tackling complex and wicked problems.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Scholars of local government have repeatedly lamented the lack of literature on the subject (e.g., Mowbray 1997; Pini, Previte, Haslam & McKenzie 2007). As Dollery, Marshall and Worthington (2003: 1) have commented, local government has often been the ‘poor cousin of its more exalted relatives in terms of the attention it attracts from the research community.’ The exalted relatives Dollery et al. (2003) refer to are national political environments, where women’s participation has elicited significant attention. However, the dearth of research on the specific subject of women’s representation in local government is rarely acknowledged (Neyland & Tucker 1996; Whip & Fletcher 1999). This edited book attempts to redress this situation. Each chapter applies an explicit gender analysis to their specific topic of focus, making ‘gender visible in social phenomenon; [and] asking if, how, and why social processes, standards, and opportunities differ systematically for women and men’ (Howard, Risman & Sprague 2003: 1). These analyses in the local government context are critical for understanding the extent and nature of balanced representation at all levels of government. Furthermore, some women start their elective careers serving on school boards, city or town councils or as mayors, before progressing to state and national legislative offices. Hence, the experiences of women in local government illustrate broader notions of democracy and may for some individual women, shape their opportunities further along the political pipeline.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We treat two related moving boundary problems. The first is the ill-posed Stefan problem for melting a superheated solid in one Cartesian coordinate. Mathematically, this is the same problem as that for freezing a supercooled liquid, with applications to crystal growth. By applying a front-fixing technique with finite differences, we reproduce existing numerical results in the literature, concentrating on solutions that break down in finite time. This sort of finite-time blow-up is characterised by the speed of the moving boundary becoming unbounded in the blow-up limit. The second problem, which is an extension of the first, is proposed to simulate aspects of a particular two-phase Stefan problem with surface tension. We study this novel moving boundary problem numerically, and provide results that support the hypothesis that it exhibits a similar type of finite-time blow-up as the more complicated two-phase problem. The results are unusual in the sense that it appears the addition of surface tension transforms a well-posed problem into an ill-posed one.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

PSA-RP2 is a variant transcript expressed from the PSA gene that is conserved in gorillas, chimpanzees and humans suggesting a particular relevance for this transcript in these primates. We demonstrated by qRT-PCR that PSA-RP2 is upregulated in prostate cancer compared with benign prostatic hyperplasia tissues. The PSA-RP2 protein was not detected in seminal fluid and was cytoplasmically localised but not secreted from LNCaP or transfected PC3 prostate cells, despite secretion from transfected Cos-7 and HEK293 kidney cell lines. PSA-RP2-transfected PC3 cells showed slightly decreased proliferation and increased migration towards PC3-conditioned medium that could suggest a functional role in prostate cancer.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The number of children with special health care needs surviving infancy and attending school has been increasing. Due to their health status, these children may be at risk of low social-emotional and learning competencies (e.g., Lightfoot, Mukherjee, & Sloper, 2000; Zehnder, Landolt, Prchal, & Vollrath, 2006). Early social problems have been linked to low levels of academic achievement (Ladd, 2005), inappropriate behaviours at school (Shiu, 2001) and strained teacher-child relationships (Blumberg, Carle, O‘Connor, Moore, & Lippmann, 2008). Early learning difficulties have been associated with mental health problems (Maughan, Rowe, Loeber, & Stouthamer-Loeber, 2003), increased behaviour issues (Arnold, 1997), delinquency (Loeber & Dishion, 1983) and later academic failure (Epstein, 2008). Considering the importance of these areas, the limited research on special health care needs in social-emotional and learning domains is a factor driving this research. The purpose of the current research is to investigate social-emotional and learning competence in the early years for Australian children who have special health care needs. The data which informed this thesis was from Growing up in Australia: The Longitudinal Study of Australian Children. This is a national, longitudinal study being conducted by the Commonwealth Department of Families, Housing, Community Services and Indigenous Affairs. The study has a national representative sample, with data collection occurring biennially, in 2004 (Wave 1), 2006 (Wave 2) and 2008 (Wave 3). Growing up in Australia uses a cross-sequential research design involving two cohorts, an Infant Cohort (0-1 at recruitment) and a Kindergarten Cohort (4-5 at recruitment). This study uses the Kindergarten Cohort, for which there were 4,983 children at recruitment. Three studies were conducted to address the objectives of this thesis. Study 1 used Wave 1 data to identify and describe Australian children with special health care needs. Children who identified as having special health care needs through the special health care needs screener were selected. From this, descriptive analyses were run. The results indicate that boys, children with low birth weight and children from families with low levels of maternal education are likely to be in the population of children with special health care needs. Further, these children are likely to be using prescription medications, have poor general health and are likely to have specific condition diagnoses. Study 2 used Wave 1 data to examine differences between children with special health care needs and their peers in social-emotional competence and learning competence prior to school. Children identified by the special health care needs screener were chosen for the case group (n = 650). A matched case control group of peers (n = 650), matched on sex, cultural and linguistic diversity, family socioeconomic position and age, were the comparison group. Social-emotional competence was measured through Social/Emotional Domain scores taken from the Growing up in Australia Outcome Index, with learning competence measured through Learning Domain scores. Results suggest statistically significant differences in scores between the two groups. Children with special health care needs have lower levels of social-emotional and learning competence prior to school compared to their peers. Study 3 used Wave 1 and Wave 2 data to examine the relationship between special health care needs at Wave 1 and social-emotional competence and learning competence at Wave 2, as children started school. The sample for this study consisted of children in the Kindergarten Cohort who had teacher data at Wave 2. Results from multiple regression models indicate that special health care needs prior to school (Wave 1) significantly predicts social-emotional competence and learning competence in the early years of school (Wave 2). These results indicate that having special health care needs prior to school is a risk factor for the social-emotional and learning domains in the early years of school. The results from these studies give valuable insight into Australian children with special health care needs and their social-emotional and learning competence in the early years. The Australia population of children with special health care needs were primarily male children, from families with low maternal education, were likely to be of poor health and taking prescription medications. It was found that children with special health care needs were likely to have lower social-emotional competence and learning competence prior to school compared to their peers. Results indicate that special health care needs prior to school were predictive of lower social-emotional and learning competencies in the early years of school. More research is required into this unique population and their competencies over time. However, the current research provides valuable insight into an under researched 'at risk' population.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

With the rapid increase in electrical energy demand, power generation in the form of distributed generation is becoming more important. However, the connections of distributed generators (DGs) to a distribution network or a microgrid can create several protection issues. The protection of these networks using protective devices based only on current is a challenging task due to the change in fault current levels and fault current direction. The isolation of a faulted segment from such networks will be difficult if converter interfaced DGs are connected as these DGs limit their output currents during the fault. Furthermore, if DG sources are intermittent, the current sensing protective relays are difficult to set since fault current changes with time depending on the availability of DG sources. The system restoration after a fault occurs is also a challenging protection issue in a converter interfaced DG connected distribution network or a microgrid. Usually, all the DGs will be disconnected immediately after a fault in the network. The safety of personnel and equipment of the distribution network, reclosing with DGs and arc extinction are the major reasons for these DG disconnections. In this thesis, an inverse time admittance (ITA) relay is proposed to protect a distribution network or a microgrid which has several converter interfaced DG connections. The ITA relay is capable of detecting faults and isolating a faulted segment from the network, allowing unfaulted segments to operate either in grid connected or islanded mode operations. The relay does not make the tripping decision based on only the fault current. It also uses the voltage at the relay location. Therefore, the ITA relay can be used effectively in a DG connected network in which fault current level is low or fault current level changes with time. Different case studies are considered to evaluate the performance of the ITA relays in comparison to some of the existing protection schemes. The relay performance is evaluated in different types of distribution networks: radial, the IEEE 34 node test feeder and a mesh network. The results are validated through PSCAD simulations and MATLAB calculations. Several experimental tests are carried out to validate the numerical results in a laboratory test feeder by implementing the ITA relay in LabVIEW. Furthermore, a novel control strategy based on fold back current control is proposed for a converter interfaced DG to overcome the problems associated with the system restoration. The control strategy enables the self extinction of arc if the fault is a temporary arc fault. This also helps in self system restoration if DG capacity is sufficient to supply the load. The coordination with reclosers without disconnecting the DGs from the network is discussed. This results in increased reliability in the network by reduction of customer outages.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Machine learning has become a valuable tool for detecting and preventing malicious activity. However, as more applications employ machine learning techniques in adversarial decision-making situations, increasingly powerful attacks become possible against machine learning systems. In this paper, we present three broad research directions towards the end of developing truly secure learning. First, we suggest that finding bounds on adversarial influence is important to understand the limits of what an attacker can and cannot do to a learning system. Second, we investigate the value of adversarial capabilities-the success of an attack depends largely on what types of information and influence the attacker has. Finally, we propose directions in technologies for secure learning and suggest lines of investigation into secure techniques for learning in adversarial environments. We intend this paper to foster discussion about the security of machine learning, and we believe that the research directions we propose represent the most important directions to pursue in the quest for secure learning.