FEM calibrated ARMAX model updating method for time domain damage identification

Due to environmental loads, mechanical damages, structural aging and human factors, civil infrastructure inevitably deteriorate during their service lives. Since their damage may claim human lives and cause significant economic losses, how to identify damages and assess structural conditions timely and accurately has drawn increasingly more attentions from structural engineering community worldwide. In this study, a fast and sensitive time domain damage identification method will be developed. To do this, a finite element model of a steel pipe laid on the soil is built and the structural responses are simulated under different damage scenarios. Based on the simulated data, an Auto Regressive Moving Average Exogenous (ARMAX) model is then built and calibrated. The calibrated ARMAX model is used to identify different damage scenarios through model updating process using clonal selection algorithm (CSA). The results demonstrate the application potential of the proposed method in identifying the pipeline conditions. To further verify its performance, laboratory tests of a steel pipe laid on the soil with and without soil support (free span damage) are carried out. The identification results of pipe-soil system show that the proposed method is capable of identifying damagein a complex structural system. Therefore, it can be applied to identifying pipeline conditions.

Evaluation of salmon farming effects on marine systems in the inner seas of southern Chile : a large-scale mensurative experiment

The impact of salmon farming on the environment has been widely studied; there is, however, no consensus on the magnitude and quality of these effects and little information on their extent over large salmon farming areas. Forty-three salmon farm sites of which 29 are in full operation and grouped in nine locations in southern Chile were evaluated. Using statistical methods (two-way anova), no effects were found on water column variables such as nitrate, ammonia, orthophosphate and chlorophyll, whereas they were significant on sediment variables such as nitrogen (N), phosphorus (P) and organic carbon (OC), among others. Natural variability evaluation of some parameters revealed that P in sediments had the lowest coefficient of variation (23.2%) when compared with N (65.2%), particulate organic matter (POM) (139%) and OC (39%), and showed more marked salmon farming effects with no locality effects. Four of the nine locations showed stronger effects on sediments, with average P values ranging from 150 to 230 mmol that were six to nine times higher than in control sites (25 mmol). Nitrogen and carbon in sediments, while showing significant effects on salmon farming, also showed locality effects that revealed other biogenic processes influencing sediment composition. Thus, P in sediments was proposed as a promising indicator of impact on salmon farming, although the relationship with fauna in sediments was not linear and somewhat variable; more research is therefore needed to understand such connections. Considering entire geographical locations, no relationship was found between sediment conditions under salmon cages and the condition of the water column at a farm. This may indicate the possibility of high dilution rates and recycling processes, which so far preclude the detection of more global impacts beyond the cages shadow.

Six million in Melbourne or a network of sustainable midi-cities? A thought experiment

By 2050, it is projected that Melbourne will have a population of between 5.6 and 6.4 million (DPCD, 2012), an increase of nearly 50% above its current level. Despite Melbourne's status as the world's most liveable city, a recent survey found that Australians in general found smaller cities are better places to live and bring up families (Perkins, 2013). The Grattan Institute's report entitled "The Cities We Need" was "an invitation to a conversation" about our future cities (Kelly, 2010:5). One idea not canvassed in the report was that of decentralization to accommodate Melbourne's projected growth. In its discussion paper, "Let's Talk about the Future", the Victorian State Government proposes that Melbourne become a 'polycentric city' linked to its regional cities (DPCD, 2012). While growth in the present regional cities is acknowledged, the possibility that these and other new regional cities could absorb the future population projected for Melbourne is not considered, nor that these regional cities could be transformed into 'sustainable cities'. This paper explores the idea that a network of smaller 'midi-cities, based on the sustainable city concept of Sweden, might provide a better alternative to concentrated growth in one city. Fifteen new cities of 150,000 would be required to absorb the projected extra 2.3 million Victorian residents. The paper analyses the energy, food, water and land requirements of a typical sustainable city. The new cities would require approximately 12% of the State's land area for food and energy supply, as well as the built environment.

Does coloniality improve foraging efficiency and nestling provisioning? A field experiment in the wild Zebra Finch

The foraging benefits of coloniality, whereby colony members exchange information about food location, have been suggested as a primary factor influencing the evolution of coloniality. However, despite its longstanding popularity, this hypothesis has rarely been tested experimentally. Here, we conducted a field experiment in the wild Zebra Finch Taeniopygia guttata to test whether colonial birds are better at finding food than solitary individuals. We manipulated food patch location and directly measured foraging activity of many colonial and solitary parents at those patches using an electronic monitoring system. We provided nesting sites in excess to alleviate nest site competition and manipulated brood size to eliminate the possible correlation between brood size, nesting density, and individual quality (including foraging activity). We found that solitary birds found experimental food patches first, closely followed by colonial birds. Moreover, solitary parents adjusted the amount of food per nestling to experimental brood size, whereas colonial parents did not, although overall, nestlings were fed more per capita in colonial than in solitary nests. In addition, brood size and, to a lesser extent, nesting density negatively affected nestling growth. Therefore, with the effect of provisioning rate, sibling competition, and cost of coloniality combined, nestling mass was not affected by the brood manipulation in solitary nests, whereas nestlings were lighter in enlarged than in reduced broods in colonies. Our results therefore suggest that individuals settling in solitary nests were intrinsically better foragers and more optimal parents. While they do not invalidate the possibility of information transfer at colonies, our findings highlight the importance of considering settlement bias in future studies and add to the existing evidence that the effects of nesting density on fitness are both complex and multiple.

Estimating wetland values: A comparison of benefit transfer and choice experiment values

The main purpose of thesis is to estimate the value of the ecosystem services of the Bung Khong Long through two techniques. The per hectare value estimated by economic valuation method is US$ 976 per annum. MRA-benefit transfer approach produces values of between US$ 396 and US$ 1,369 per annum.

A protocol for a discrete choice experiment: understanding preferences of patients with cancer towards their cancer care across metropolitan and rural regions in Australia.

Medical decision-making in oncology is a complicated process and to date there are few studies examining how patients with cancer make choices with respect to different features of their care. It is also unknown whether patient choices vary by geographical location and how location could account for observed rural and metropolitan cancer differences. This paper describes an ongoing study that aims to (1) examine patient and healthcare-related factors that influence choices of patients with cancer; (2) measure and quantify preferences of patients with cancer towards cancer care using a discrete choice experiment (DCE) and (3) explore preference heterogeneity between metropolitan and rural locations.

Mortgage-Backed Securities (MBS): Is It a Curse or a Blessing for the Australian Home Loan Market? A Natural Experiment

The Australian home loan market has seen a significant and persistent boom over more than two decades. Theextant literature exploring the underlying factors explaining this boom has predominantly looked at thedemand side rather than the supply side. In this paper, we look at a major supply-side issue, the introductionof mortgage-backed securities and its likely impact on the home loan market. In doing so, we have developeda mathematical model that theorises this likely relationship. Our mathematical model predicts possibleexistence of an unstable equilibrium in the home loan market in the presence of mortgage-backed securities.We have subsequently backed up our theoretical exercise with sound empirical evidence acquired andanalysed as a natural experiment in the Australian scenario using quarterly market data on home loans andmortgage-backed securities data for a 36-year period from 1976 to 2012. Using unknown structural breaktests, we have identified significant breaks around late 1992 to mid-1995, clearly indicating that there weresignificant changes in the housing market due to the introduction of mortgage-backed securities in early1993. We have also performed a stability test confirming that under certain conditions this market canbecome unstable.

Femoroacetabular impingement osteoplasty is any resected amount safe? A laboratory based experiment with sawbones

There is an increased risk of fracture following osteoplasty of the femoral neck for cam-type femoroacetabular impingement (FAI). Resection of up to 30% of the anterolateral head–neck junction has previously been considered to be safe, however, iatrogenic fractures have been reported with resections within these limits. We re-evaluated the amount of safe resection at the anterolateral femoral head–neck junction using a biomechanically consistent model.In total, 28 composite bones were studied in four groups: control, 10% resection, 20% resection and 30% resection. An axial load was applied to the adducted and flexed femur. Peak load, deflection at time of fracture and energy to fracture were assessed using comparison groups.There was a marked difference in the mean peak load to fracture between the control group and the 10% resection group (p < 0.001). The control group also tolerated significantly more deflection before failure (p < 0.04). The mean peak load (p = 0.172), deflection (p = 0.547), and energy to fracture (p = 0.306) did not differ significantly between the 10%, 20%, and 30% resection groups.Any resection of the anterolateral quadrant of the femoral head–neck junction for FAI significantly reduces the load-bearing capacity of the proximal femur. After initial resection of cortical bone, there is no further relevant loss of stability regardless of the amount of trabecular bone resected.Based on our findings we recommend any patients who undergo anterolateral femoral head–neck junction osteoplasty should be advised to modify their post-operative routine until cortical remodelling occurs to minimise the subsequent fracture risk.

Congestion pricing and active transport - evidence from five opportunities for natural experiment

Congestion pricing schemes have been implemented in cities worldwide as a means of addressing externalities associated with inefficient price signals in transport systems. Limited evidence exists however on the secondary impacts of these schemes, which may include both environmental and health benefits associated with a resultant reduction in motor vehicle usage. There is increasing recognition that transport behaviours may play a role as opportunistic population level targets to reduce physical inactivity. Yet limited evidence currently exists on the effectiveness of transport interventions, such as congestion pricing schemes, for improving physical activity levels.This study aims to examine the physical activity effects of congestion pricing, with the health benefits of physical activity well established. Congestion pricing schemes implemented internationally were considered as 'natural experiments' and evidence of modal shift from vehicle to active forms of transport or physical activity effect was reviewed. Twelve studies were included from a search of peer-reviewed and 'grey' literature, with overall evidence for a physical activity or modal shift effect considered weak. The quality of the available evidence was also considered to be low.This is not to say that congestion pricing schemes may not have important secondary physical activity related health benefits. Instead, this review highlights the paucity of evidence that has been collected from real-world implementation of congestion pricing schemes. Given the growing recognition of the importance of distal mediators and determinants of health and the need for an 'all-of-government' approach more and better quality evidence of effectiveness of transport interventions for a broad range of outcomes, including health, is required. Significant barriers to the collection of such evidence exist, with strategies for overcoming some of these barriers identified. Only with a better understanding of the full range of potential health impacts can transport policy be fully utilised as a tool for population health.