Specialized Testing of Asphalt Cements from Various ADOT&PF Paving Projects

The Alaska Department of Transportation and Public Facilities (ADOT&PF) sampled five different asphalt cements for specialized testing at Queen’s University in Kingston, Ontario. This report documents and discusses the findings. The tested asphalts were: PG 58-34, PG 52-40D, PG 52-40N, PG 58-28, and PG 64-28. Testing results showed that grade losses according to Ontario’s LS-308 Extended Bending Beam Rheometer (EBBR) ranged from 3.4°C to 6.3°C. Losses according to Ontario’s LS-228 Modified Pressure Aging Vessel (PAV) ranged from 0°C to 7.3°C. Grade losses of 3°C and higher are significant in terms of their ability to reduce pavement life cycles. Double-edge-notched tension (DENT) tests according to Ontario’s LS-299 DENT protocol were done on PAV residues. The critical crack tip opening displacement (CTOD) was determined and, at 15°C, it varied from a low of 19 mm for the PG 58-28 to a high of 175 mm for the PG 58-34. The PG 58- 40D showed a CTOD of 139 mm, contrasting with the low polymer PG 52-40N at only 36 mm, a nearly four-fold difference. All the results obtained from this specialized testing effort suggest that these materials will provide significant differences in performance. This report provides recommendations on how to obtain better value for money by implementing a few simple changes to the ADOT&PF asphalt cement specifications

A Phase Lag between Disk and Corona in GRMHD Simulations of Precessing Tilted Accretion Disks

In the course of its evolution, a black hole (BH) accretes gas from a wide range of directions. Given a random accretion event, the typical angular momentum of an accretion disc would be tilted by $\sim$60$^\circ$ relative to the BH spin. Misalignment causes the disc to precess at a rate that increases with BH spin and tilt angle. We present the first general-relativistic magnetohydrodynamic (GRMHD) simulations spanning a full precession period of highly tilted (60$^\circ$), moderately thin ($h/r=0.1$) accretion discs around a rapidly spinning ($a\simeq0.9$) BH. While the disc and jets precess in phase, we find that the corona, sandwiched between the two, lags behind by $\gtrsim 10^{\circ}$. For spectral models of BH accretion, the implication is that hard non-thermal (corona) emission lags behind the softer (disc) emission, thus potentially explaining some properties of the hard energy lags seen in Type-C low frequency quasi-periodic oscillations in X-Ray binaries. While strong jets are unaffected by this disc-corona lag, weak jets stall when encountering the lagging corona at distances $r \sim 100$ black hole radii. This interaction may quench large-scale jet formation.Comment: 5 pages, 4 figures, submitted to MNRAS, see YouTube playlist for 3D renderings: https://www.youtube.com/playlist?list=PLDO1oeU33GwmwOV_Hp9s7572JdU8JPSS

A resource survey of the coastal lands from Vlaming Head to Tantabiddi Well, West Cape Range region

The report comprise four parts; a brief review of the area\u27s climate, discussion of the geomorphology of the major landform units, an assessment of the potential erosion hazards of the surveyed landforms, and recommendations for development

A land resource survey of the Fall Point coastline, Broome, W.A.

The purpose of this study was to find a suitable location for a bird observatory and provide adequate coastal land resource data for the area. The main selection criteria and conditions were: the location was closely adjacent to major wader roosting and feeding sites; all-seasons access was required; the location provided a site of around 2 1/2 hectares to provide space for one or more buildings, camp ground and associated facilities ; anticipated access tracks, site developments and levels of use

Differential changes in production measures for an estuarine-resident sparid in deep and shallow waters following increases in hypoxia

This study determined how productivity measures for a fish species in different water depths of an estuary changed in response to the increase in hypoxia in deep waters, which had previously been shown to occur between 1993–95 and 2007–11. Annual data on length and age compositions, body mass, growth, abundance, biomass, production and production to biomass ratio (P/B) were thus determined for the estuarine-resident Acanthopagrus butcheri in nearshore shallow (<2 m) and offshore deep waters (2–6 m) of the upper Swan River Estuary in those two periods. Length and age compositions imply that the increase in hypoxia was accompanied by the distribution of the majority of the older and larger A. butcheri changing from deep to shallow waters, where the small fish typically reside. Annual densities, biomass and production in shallow waters of <0.02 fish m−2, 2–4 g m−2 and ∼2 g m−2 y−1 in the earlier period were far lower than the 0.1–0.2 fish m−2, 8–15 g m−2 and 5–10 g m−2 y−1 in the later period, whereas the reverse trend occurred in deep waters, with values of 6–9 fish net−1, 2000–3900 g net−1, 900–1700 g net−1 y−1 in the earlier period vs < 1.5 fish net−1, ∼110 g net−1 and 27–45 g net−1 y−1 in the later period. Within the later period, and in contrast to the trends with annual abundance and biomass, the production in shallow waters was least during 2008/09, rather than greatest, reflecting the slow growth in that particularly cool year. The presence of substantial aggregations of both small and large fish in shallow waters accounts for the abundance, biomass and production in those waters increasing between those periods and thus, through a density-dependent effect, provide a basis for the overall reduction in growth. In marked contrast to the trends with the other three production measures, annual production to biomass ratios (P/B) in shallow waters in the two years in the earlier period, and in three of the four years of the later period, fell within the same range, i.e. 0.6–0.9 y−1, but was only 0.2 y−1 in 2008/09, reflecting the poor growth in that year. This emphasises the need to obtain data on P/B for a number of years when considering the implications of the typical P/B for a species in an estuary, in which environmental conditions and the growth of a species can fluctuate markedly between years