Performance of some unbound roadbase materials from Queensland = Performance de certains matériaux granulaires de base du Queensland

This paper summarises recent investigations into characterisation and performance of unbound roadbase materials carried out by Main Roads, Queensland (QDMR), on road projects across the state. Performance based tests such as the Repeated Load Triaxial (RLT) and the Wheel Tracker (WT) are the primary tools which are increasingly used by QDMR to overcome the limitations of simple specification type tests. This paper shows the inadequacy of current specification tests to rank material performance. The performance based tests show that the properties of the coarse aggregate alone are inadequate for sound performance; enable the contribution to mechanical behaviour by plastic fines with high matric suction to be assessed,- further, and facilitates ranking of material behaviour. Simple shakedown analyses undertaken yield similar material rankings. Finally, some materials from the performance based characterisation are compared with Falling Weight Deflectometer (FWD) in-service pavement performance data.

Stoichiometric and kinetic characterisation of Nitrobacter in mixed culture by decoupling the growth and energy generation processes

The growth, maintenance and lysis processes of Nitrobacter were characterised. A Nitrobacter culture was enriched in a sequencing batch reactor (SBR). Fluorescent in situ hybridisation showed that Nitrobacter constituted 73% of the bacterial population. Batch tests were carried out to measure the oxygen uptake rate and/or nitrite consumption rate when both nitrite and CO2 were in excess, and in the absence of either of these two substrates. The results obtained, along with the SBR performance data, allowed the determination of the maintenance coefficient and in situ cell lysis rate of Nitrobacter. Nitrobacter spends a significant amount of energy for maintenance, which varies considerably with the specific growth rate. At maximum growth, Nitrobacter consume nitrite at a rate of 0.042 mgN/mgCOD(biomass)center dot h for maintenance purposes, which increases more than threefold to 0.143 mgN/mgCOD(biomass)center dot h in the absence of growth. In the SBR, where Nitrobacter grew at 40% of its maximum growth rate, a maintenance coefficient of 0.113 mgN/mgCOD center dot h was found, resulting in 42% of the total amount of nitrite being consumed for maintenance. The above three maintenance coefficient values obtained at different growth rates appear to support the maintenance model proposed in Pirt (1982). The in situ lysis rate of Nitrobacter was determined to be 0.07/day under aerobic conditions at 22 C and pH 7.3. Further, the maximum specific growth rate of Nitrobacter was estimated to be 0.02/h (0.48/day). The affinity constant of Nitrobacter with respect to nitrite was determined to be 1.50 mgNO(2)(-)-N/L, independent of the presence or absence of CO2. (c) 2006 Wiley Periodicals, Inc.

Design for sampling - preliminary exploration

A modern mineral processing plant represents a substantial investment. During the design process, there is often a period when costs (or revenues) must be compensated for by cuts in capital expenditure. In many cases, sampling and measurement equipment provides a soft target for such 'savings'. This process is almost analgous to reducing the capital investment in a corner store by not including a cash register. The consequences will be quite similar - a serious lack of sound performance data and plenty of opportunities for theft - deliberate or inadvertent. This paper makes the case that investment in sampling and measurement equipment is more cost-effective during the design phase. Further, a strong measurement culture will have many benefits including the ability to take advantage of small gains. In almost any business, there are many more opportunities to make small gains than to make large, step changes. In short, if a project cannot justify the cost of accurate and reliable measurement of its performance, it probably should not be a project at all.

Stoichiometric and kinetic characterisation of Nitrosomonas sp in mixed culture by decoupling the growth and energy generation processes

A novel method that relies on the decoupling of the energy production and biosynthesis processes was used to characterise the maintenance, cell lysis and growth processes of Nitrosomonas sp. A Nitrosolnonas culture was enriched in a sequencing batch reactor (SBR) with ammonium as the sole energy source. Fluorescent in situ hybridization (FISH) showed that Nitrosomonas bound to the NEU probe constituted 82% of the bacterial population, while no other known ammonium or nitrite oxidizing bacteria were detected. Batch tests were carried out under conditions that both ammonium and CO, were in excess, and in the absence of one of these two substrates. The oxygen uptake rate and nitrite production rate were measured during these batch tests. The results obtained from these batch tests, along with the SBR performance data, allowed the determination of the maintenance coefficient and the in situ cell lysis rate, as well as the maximum specific growth rate of the Nitrosomonas culture. It is shown that, during normal growth, the Nitrosomonas culture spends approximately 65% of the energy generated for maintenance. The maintenance coefficient was determined to be 0.14 - 0.16 mgN mgCOD(biomass)(-1) h(-1), and was shown to be independent of the specific growth rate. The in situ lysis rate and the maximum specific growth rate of the Nitrosomonas culture were determined to be 0.26 and 1.0 day(-1) (0.043 h(-1)), respectively, under aerobic conditions at 30 degrees C and pH7. (c) 2006 Elsevier B.V. All rights reserved.

Analytical electron microscopy of proton exchange membrane fuel cells

Microtome sections of proton exchange membrane cells produce a wide range of information ranging from macroscopic distribution of components through specimens in which the detailed distribution of catalyst particles can be observed. Using modern data management practices it is possible to combine information at different scales and correlate processing and performance data. Analytical electron microscopy reveals the compositional variations across used cells at the electrolyte/electrode interface. In particular analytical techniques indicate that sulphur concentrations are likely to diminish at the interface Nafion/anode interface. © 2006 Elsevier B.V. All rights reserved.

Skin cancer clinics in Australia: workload profile and performance indicators from an analysis of billing data

Objective: To describe the workload profile in a network of Australian skin cancer clinics. Design and setting: Analysis of billing data for the first 6 months of 2005 in a primary-care skin cancer clinic network, consisting of seven clinics and staffed by 20 doctors, located in the Northern Territory, Queensland and New South Wales. Main outcome measures: Consultation to biopsy ratio (CBR); biopsy to treatment ratio (BTR); number of benign naevi excised per melanoma (number needed to treat [NNT]). Results: Of 69780 billed activities, 34 622 (49.6%) were consultations, 19 358 (27.7%) biopsies, 8055 (11.5%) surgical excisions, 2804 (4.0%) additional surgical repairs, 1613 (2.3%) non-surgical treatments of cancers and 3328 (4.8%) treatments of premalignant or non-malignant lesions. A total of 6438 cancers were treated (116 melanomas by excision, 4709 non-melanoma skin cancers [NMSCs] by excision, and 1613 NMSCs non-surgically); 5251 (65.2%) surgical wounds were repaired by direct suture, 2651 (32.9%) by a flap (of which 44.8% were simple flaps), 42 (0.5%) by wedge excision and 111 (1.4%) by grafts. The CBR was 1.79, the BTR was 3.1 and the NNT was 28.6. Conclusions: In this network of Australian skin cancer clinics, one in three biopsies identified a skin cancer (BTR, 3.1), and about 29 benign lesions were excised per melanoma (NNT, 28.6). The estimated NNT was similar to that reported previously in general practice. More data are needed on health outcomes, including effectiveness of treatment and surgical repair.

Dissecting query performance in logical data models: Parsimony vs. greater ontological clarity

Even when data repositories exhibit near perfect data quality, users may formulate queries that do not correspond to the information requested. Users’ poor information retrieval performance may arise from either problems understanding of the data models that represent the real world systems, or their query skills. This research focuses on users’ understanding of the data structures, i.e., their ability to map the information request and the data model. The Bunge-Wand-Weber ontology was used to formulate three sets of hypotheses. Two laboratory experiments (one using a small data model and one using a larger data model) tested the effect of ontological clarity on users’ performance when undertaking component, record, and aggregate level tasks. The results indicate for the hypotheses associated with different representations but equivalent semantics that parsimonious data model participants performed better for component level tasks but that ontologically clearer data model participants performed better for record and aggregate level tasks.