CCD Image System Design And Exploitation: Experiences And Lessons Learned

The use of digital imagery, acquired through charge-coupled devices (CCDs) either by the scanning of hard copy film or direct capture through the use of a CCD camera, has fundamentally changed the photogrammetric environment. In order to fully exploit these digital image data, the photogrammetrist must employ system design, implementation philosophies and processing methodologies different from those of traditional film based photogrammetry. It is now possible for these new photogrammetric systems to be operated from low cost, high performance PC and Macintosh class commercial hardware, using vendor supplied software for user developed applications. This paper explores lessons learned and experiences gained from low cost, digital photogrammetric system development and CCD image exploitation. Examples and discussion presented in this paper include: (1) integration of user developed applications with commercial hardware and software; (2) user interface design; (3) validation of processing algorithms within the digital image domain; (4) system calibration; (5) digital image data handling, management and storage; and (6) image data compression. The film based photogrammetric system provides the point of departure to digital photogrammetry. Technical knowledge, system design and implementation and CCD image exploitation provide the experience.     

Testing tidal-torque theory – I. Spin amplitude and direction

We evaluate the success of linear tidal-torque theory (TTT) in predicting galactic-halo spin using a cosmological N -body simulation with thousands of well-resolved haloes. The protohaloes are identified by tracing today's haloes back to the initial conditions. The TTT predictions for the protohaloes match, on average, the spin amplitudes of the virialized haloes of today, if linear growth is assumed until ∼ t ₀/3, or  55–70  per cent of the halo effective turn-around time. This makes it a useful qualitative tool for understanding certain average properties of galaxies, such as total spin and angular momentum distribution within haloes, but with a random scatter of the order of the signal itself. Non-linear changes in spin direction cause a mean error of ∼50° in the TTT prediction at t ₀, such that the linear spatial correlations of spins on scales ≥1  h ⁻¹ Mpc are significantly weakened by non-linear effects. This questions the usefulness of TTT for predicting intrinsic alignments in the context of gravitational lensing. We find that the standard approximations made in TTT, including a second-order expansion of the Zel'dovich potential and a smoothing of the tidal field, provide close-to-optimal results.     

New developments in water efficiency

1Water LossInitiativesUnaccounted-for water(or unbilled water)has beenreceiving newscrutiny at both the state and nationallevels.For years,water conservationeffortsin Europehave emphasized reduction in water loss to a muchgreater extent thaninthe United S…     

Preferential leaching and the age of radiation damage from alpha decay in minerals

Preferential release into solution of radionuclides that result from alpha decay is a contributor to natural isotopic disequilibrium. Such release is critical to geochemical understanding of alpha-decay products and would be an undesirable characteristic of solidified nuclear waste in deep geological formations. Spontaneous annealing of the radiation damage that is responsible for the preferential release is shown to diminish the effect in thorianite and uraninite which we have found to be 550 to 1000 M.y. old, respectively. Leaching experiments and measurements of the thorium and uranium isotopes show that there is strongly enhanced release of short-lived ²²⁸Th relative to ²³²Th, but only slight enhancement of long-lived ²³⁴U and ²³⁰Th relative to ²³⁸U and ²³²Th. These results are interpreted in terms of natural annealing of damage occurring on a time scale between the ~10 and 10⁵ years of the alpha-decay products. With a simple assumption actual times for the survival of the enhanced leaching in these minerals are ~ 15,000 years.     

The lunar atmosphere

In contrast to earth, the atmosphere of the moon is exceedingly tenuous and appears to consist mainly of noble gases. The solar wind impinges on the lunar surface, supplying detectable amounts of helium, neon and ³⁶Ar. Influxes of solar wind protons and carbon and nitrogen ions are significant, but atmospheric gases containing these elements have not been positively identified. Radiogenic ⁴⁰Ar and ²²²Rn produced within the moon have been detected. The present rate of effusion of argon from the moon accounts for about 0.4% of the total production of ⁴⁰Ar due to decay of ⁴⁰K if the average abundance of potassium in the moon is 1000 ppm. Lack of weathering processes in the regolith suggests that most of the atmospheric ⁴⁰Ar originates deep in the lunar interior, perhaps in a partially molten core. If so, other gases may be vented along with the argon.     

A lithogeochemical approach to Stratigraphical problems at the Millstream potash deposit, New Brunswick, Canada

A lithogeochemical study was undertaken of the Millstream potash deposit, New Brunswick, Canada, a marine evaporite deposit with a complex depositional and tectonic history. The objective of the study was to determine if potash intersections in boreholes represent different geological horizons, or the same stratum repeated by folding or faulting. The deposit is found at a depth of 800–1000 m.Water-soluble and -insoluble fractions of drill core from five ore zones in four holes were analyzed using multielement ICP instrumentation following sequential hot water and aqua regia leaches. Meaningful variations in the data for the different ore zones were evident for eight elements in the water-soluble portion, and for seventeen elements in the water-insoluble residue. These results characterize a lowermost sylvinite unit which is relatively depleted in most elements, with the exception of Mg and Al in the residue. Regression analysis indicates a weak correlation between Fe and the common base metals, in contrast to the immediately overlying sylvinite unit which is relatively enriched in most elements, including Fe, but where Fe apparently exerts no control over the base metals. Cluster analysis confirms these two units are easily distinguished from each other. The upper two ore horizons are distinguishable from the lower units on the basis of different abundances of some elements, such as water-soluble B, and on the strong scavenging abilities of Fe on the common base metals.No single element is able to uniquely fingerprint a particular sylvinite horizon, but suites of elements are able to classify each horizon as geochemically distinctive. The results appear to confirm the validity of the geological correlations.     

Kinematics of throughgoing fractures in jointed rocks

Throughgoing fractures play a major role in subsurface fluid flow yet the kinematics of their formation, which directly impact rock flow properties, are often difficult to establish. We investigate throughgoing fractures in the Monterey Formation of California that developed by the coalescence of pre-existing joints. At Lompoc Landing, throughgoing fractures fall into three main groups: linked, linked with aperture, and breccia zones. The segmented nature of their walls provides numerous piercing points to firmly establish the sense of displacement. Analysis of displacement vectors derived from piercing points demonstrates that the NW–SE trending throughgoing fractures, often interpreted as strike–slip faults, are in fact extensional structures in origin. We suggest that this method may be applied to throughgoing fractures that form by the same mechanism in other geologic settings. Establishing kinematics of throughgoing fractures will lead to a better understanding of their contribution to subsurface fluid flow.