Experimental and Numerical Impact Analysis of Automotive Bumper Brackets Made of 2D Triaxially Braided CFRP Composites.

The impact behavior of carbon fiber epoxy bumper brackets reinforced with 2D biaxial and 2D triaxial braids was experimentally and numerically analyzed. For this purpose, a phenomenological damage model was modified and implemented as a user material in ABAQUS. It was hypothesized that all input parameters could be determined from a suitable high-speed test program. Therefore, novel impact test device was designed, developed and integrated into a drop tower. Drop tower tests with different impactor masses and impact velocities at different bumper bracket configurations were conducted to compare the numerically predicted deformation and damage behavior with experimental evidence. Good correlations between simulations and tests were found, both for the global structural deformation, including fracture, and local damage entities in the impact zone. It was proven that the developed phenomenological damage models can be fully applied for present-day industrial problems.

Understanding urban water performance at the city-region scale using an urban water metabolism evaluation framework.

Water sensitive interventions are being promoted to reduce the adverse impacts of urban development on natural water cycles. However it is currently difficult to know the best strategy for their implementation because current and desired urban water performance is not well quantified. This is particularly at the city-region scale, which is important for strategic urban planning. This work aimed to fill this gap by quantifying the water performance of urban systems within city-regions using 'urban water metabolism' evaluation, to inform decisions about water sensitive interventions. To do this we adapted an existing evaluation framework with new methods. In particular, we used land use data for defining system boundaries, and for estimating natural hydrological flows. The criteria for gauging the water performance were water efficiency (in terms of water extracted externally) and hydrological performance (how much natural hydrological flows have changed relative to a nominated pre-urbanised state). We compared these performance criteria for urban systems within three Australian city-regions (South East Queensland, Melbourne and Perth metropolitan areas), under current conditions, and after implementation of example water sensitive interventions (demand management, rainwater/stormwater harvesting, wastewater recycling and increasing perviousness). The respective water efficiencies were found to be 79, 90 and 133 kL/capita/yr. In relation to hydrological performance, stormwater runoff relative to pre-urbanised flows was of most note, estimated to be 2-, 6- and 3- fold, respectively. The estimated performance benefits from water sensitive interventions suggested different priorities for each region, and that combined implementation of a range of interventions may be necessary to make substantive gains in performance. We concluded that the framework is suited to initial screening of the type and scale of water sensitive interventions needed to achieve desired water performance objectives.

Increased sediment loads cause non-linear decreases in seagrass suitable habitat extent.

Land-based activities, including deforestation, agriculture, and urbanisation, cause increased erosion, reduced inland and coastal water quality, and subsequent loss or degradation of downstream coastal marine ecosystems. Quantitative approaches to link sediment loads from catchments to metrics of downstream marine ecosystem state are required to calculate the cost effectiveness of taking conservation actions on land to benefits accrued in the ocean. Here we quantify the relationship between sediment loads derived from landscapes to habitat suitability of seagrass meadows in Moreton Bay, Queensland, Australia. We use the following approach: (1) a catchment hydrological model generates sediment loads; (2) a statistical model links sediment loads to water clarity at monthly time-steps; (3) a species distribution model (SDM) factors in water clarity, bathymetry, wave height, and substrate suitability to predict seagrass habitat suitability at monthly time-steps; and (4) a statistical model quantifies the effect of sediment loads on area of seagrass suitable habitat in a given year. The relationship between sediment loads and seagrass suitable habitat is non-linear: large increases in sediment have a disproportionately large negative impact on availability of seagrass suitable habitat. Varying the temporal scale of analysis (monthly vs. yearly), or varying the threshold value used to delineate predicted seagrass presence vs. absence, both affect the magnitude, but not the overall shape, of the relationship between sediment loads and seagrass suitable habitat area. Quantifying the link between sediment produced from catchments and extent of downstream marine ecosystems allows assessment of the relative costs and benefits of taking conservation actions on land or in the ocean, respectively, to marine ecosystems.

Protecting the green behind the gold: catchment-wide restoration efforts necessary to achieve nutrient and sediment load reduction targets in Gold Coast City, Australia.

The Gold Coast City is the tourist center of Australia and has undergone rapid and massive urban expansion over the past few decades. The Broadwater estuary, in the heart of the City, not only offers an array of ecosystems services for many important aquatic wildlife species, but also supports the livelihood and lifestyles of residents. Not surprisingly, there have been signs of imbalance between these two major services. This study combined a waterway hydraulic and pollutant transport model to simulate diffuse nutrient and sediment loads under past and future proposed land-use changes. A series of catchment restoration initiatives were modeled in an attempt to define optimal catchment scale restoration efforts necessary to protect and enhance the City's waterways. The modeling revealed that for future proposed development, a business as usual approach to catchment management will not reduce nutrient and sediment loading sufficiently to protect the community values. Considerable restoration of upper catchment tributaries is imperative, combined with treatment of stormwater flow from intensively developed sub-catchment areas. Collectively, initiatives undertaken by regulatory authorities to date have successfully reduced nutrient and sediment loading reaching adjoining waterways, although these programs have been ad hoc without strategic systematic planning and vision. Future conservation requires integration of multidisciplinary science and proactive management driven by the high ecological, economical, and community values placed on the City's waterways. Long-term catchment restoration and conservation planning requires an extensive budget (including political and societal support) to handle ongoing maintenance issues associated with scale of restoration determined here.

One vs. two piece customized implants to reconstruct mandibular continuity defects: a preliminary study in pig cadavers.

OBJECTIVES: The reconstruction of mandibular continuity defects by bridging plates often leads to complications. Customized mandibular implants might be an alternative option. In the present study, the stability at the bone-implant-interface of customized two-piece implants was compared to one-piece implants. METHODS: Thirty pig mandibles were randomly divided into three groups. One group (A) was left untreated and served as reference. In groups B and C, a continuity defect was created in the left mandibular side. The defects were reconstructed by customized pure titanium implants, manufactured using the LaserCUSING(®) technology. Group B received a one-piece implant; in group C a two-piece implant was inserted to reconstruct the continuity defect. The bonding strength was examined statically and dynamically under standardized conditions. Digital Image Correlation was used for distortion measurement. Different dynamic measurements were performed for orientation purposes. RESULTS: The highest bonding strength was measured for the reference group. The two-piece implant showed an increased bonding strength when compared to the one-piece design. In all pig mandibles treated with individual implants a fracture occurred on the non-operated side. This indicates a high primary stability of the bone-implant-interface. CONCLUSION: The two-piece individual mandibular implant manufactured by LaserCUSING(®) technology should be further analyzed in future studies.

Changes to chronic nitrogen loading from sewage discharges modify standing stocks of coastal phytoplankton.

Nutrient delivery in subtropical coastal systems is predominantly via acute episodic high flow events. However, continuous nutrient discharges from point sources alter these natural fluctuations in nutrient delivery, and are therefore likely to lead to different ecosystem responses. The aim of this study was to assess how a reduction in chronic sewage nutrient inputs affected chlorophyll a (chl a) concentrations in a subtropical bay, in the context of seasonal fluctuations in riverine nutrient inflows. Reduced nutrient inputs from a large sewage treatment plant (STP) resulted in lower mean dissolved inorganic nitrogen and phytoplankton chl a concentrations during both the austral summer wet and winter dry season. This was measurable within 10 y of nutrient reductions and despite the confounding effects of nutrient inflow events. Our study demonstrates that reductions in STP inputs can have significant effects on phytoplankton biomass despite confounding factors over relatively short time frames.