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103.
Zoltán Hajnal Ernő Takács Irvine R. Annesley Bhaskar Pandit 《Geophysical Prospecting》2020,68(1):129-144
In participation with numerous industrial partners, the Seismic Laboratory of the University of Saskatchewan has conducted a variety of active seismic reflection experiments; both on the west and east sides of the Athabasca Basin. Results of the investigations at Shea Creek, McArthur River and Keefe Lake illustrate that the seismic investigations deliver effective, highly relevant primary structural images of the subsurface, with resolution that no other geophysical technique can match. Correlation of similar seismic signatures, on several distant but inter-related seismic sections, allowed spatial extension of promising exploration target zones previously unrecognized. Within the three-dimensional seismic volume, comparable reflectivity patterns defined the complex areal distribution of mineralization-related fault systems. Beyond these novel contributions, extended analysis of seismic signal attributes (amplitude and frequency), optical televiewer, and full-wave sonic data offer detailed lithological characterization, including alteration zones, clay content, as well as porosity and fracture density information. Although these structural and geologically relevant anomalies are primary indicators of mineralization, presenting novel exploration advantages, the seismic method is still not a standard component of the Athabasca Basin exploration approach, due to the negative perception that ‘it is very expensive’. Comparing the costs of all geophysical techniques to the cost of a single logged drill hole illustrates that the results of a properly designed seismic data acquisition program not only leads to more effective planning of a drilling program, but also would lead to a much quicker recognition of the major mineralized zone(s), and a reduction in the number of required exploration boreholes. This integrated approach to exploration would then translate into a significant reduction of the total exploration expenditures. Unquestionably, the drilling of boreholes provides the most explicit, reliable information to a certain depth, but only within a very small area. Directly connecting the borehole information to seismic results extends the local reliable data; permitting reduction of the number of boreholes to create accurate two-dimensional or three-dimensional subsurface images and reduction of the expenditures of the total exploration program. 相似文献
104.
Turbulent Structures in a Pine Forest with a Deep and Sparse Trunk Space: Stand and Edge Regions 总被引:1,自引:0,他引:1
Sylvain Dupont Mark R. Irvine Jean-Marc Bonnefond Eric Lamaud Yves Brunet 《Boundary-Layer Meteorology》2012,143(2):309-336
Forested landscapes often exhibit large spatial variability in vertical and horizontal foliage distributions. This variability
may affect canopy-atmosphere exchanges through its action on the development of turbulent structures. Here we investigate
in neutral stratification the turbulent structures encountered in a maritime pine forest characterized by a high, dense foliated
layer associated with a deep and sparse trunk space. Both stand and edge regions are considered. In situ measurements and
the results of large-eddy simulations are used and analyzed together. In stand conditions, far from the edge, canopy-top structures
appear strongly damped by the dense crown layer. Turbulent wind fluctuations within the trunk space, where the momentum flux
vanishes, are closely related to these canopy-top structures through pressure diffusion. Consequently, autocorrelation and
spectral analyses are not quite appropriate to characterize the vertical scale of coherent structures in this type of canopy,
as pressure diffusion enhances the actual scale of structures. At frequencies higher than those associated with canopy-top
structures, wind fluctuations related to wake structures developing behind tree stems are observed within the trunk space.
They manifest themselves in wind velocity spectra as secondary peaks in the inertial subrange region, confirming the hypothesis
of spectral short-cuts in vegetation canopies. In the edge region specific turbulent structures develop just below the crown
layer, in addition to canopy-top structures. They are generated by the wind shear induced by the sub-canopy wind jet that
forms at the edge. These structures provide a momentum exchange mechanism similar to that observed at the canopy top but in
the opposite direction and with a lower magnitude. They may develop as in plane mixing-layer flows, with some perturbations
induced by canopy-top structures. Wake structures are also observed within the trunk space in the edge region. 相似文献
105.
Single-component (e.g., single-element) partition coefficients for silicate melts and the minerals that crystallize from them typically show large variations with temperature and melt composition. It is shown that, in particular cases, these variations can be calculated from two-component distribution coefficients that are practically constants, given the structural formula of the mineral and the melt composition. 相似文献
106.
Broten NW MacLeod JM Avery LW Irvine WM Hoglund B Friberg P Hjalmarson A 《The Astrophysical journal》1984,(1):L25-L29
A new interstellar molecule, methylcyanoacetylene (CH3C3N), has been detected in the molecular cloud TMC-1. The J = 8 --> 7, J = 7 --> 6, J = 6 --> 5, and J = 5 --> 4 transitions have been observed. For the first three of these, both the K = 0 and K = 1 components are present, while for J = 5 --> 4, only the K = 0 line has been detected. The observed frequencies were calculated by assuming a value of radial velocity VLSR = 5.8 km s-1 for TMC-1, typical of other molecules in the cloud. All observed frequencies are within 10 kHz of the calculated frequencies, which are based on the 1982 laboratory constants of Moises et al., so the identification is secure. The lines are broadened by hyperfine splitting, and the J = 5 --> 4, K = 0 transition shows incipient resolution into three hyperfine components. The rotational temperature determined for these observations is quite low, with 2.7 K < or = Trot < or = 4 K. the total column density is approximately 5 x 10(12) cm-2. 相似文献
107.
We report observations of the 2(12)-1(01) rotational transition of the 13C isotopic species of cyclopropenylidene (C3H2) toward TMC-1, Sgr B2, and IRC +10216 using the laboratory rest frequencies which have recently become available. Our detections allow estimates to be made of the fractional abundance of the unsubstituted similar species in these sources. The fractional abundance relative to H2, f(C3H2), is 1-2 x 10(-8) in TMC-1, and this is similar to the abundance of HCN, one of the more abundant organic molecules in the interstellar medium. In IRC +10216 f(C3H2) is one order of magnitude greater than in TMC-1. The 12C species in Sgr B2 shows a self-absorbed profile and the relative abundance of C3H2 estimated to be about an order of magnitude less than in TMC-1. 相似文献
108.
Irvine WM Brown RD Cragg DM Friberg P Godfrey PD Kaifu N Matthews HE Ohishi M Suzuki H Takeo H 《The Astrophysical journal》1988,335(2):L89-L93
We report the detection of the acetylene derivative propynal (HC triple bond CCHO) in the cold cloud TMC-1, with an abundance that is very close to that for the related species tricarbon monoxide (C3O). Propadienone, an isomer of propynal with the formula H2C=C=C=O, was not detected and is hence less abundant than either C3O or HC2CHO. 相似文献
109.
Dickens JE Irvine WM Ohishi M Ikeda M Ishikawa S Nummelin A Hjalmarson A 《The Astrophysical journal》1997,489(2):753-757
We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature T(rot) = 18 K and a molecular column density N(c-C2H4O) = 3.3 x 10(14) cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10(-11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW. 相似文献
110.
H. M. Irvine 《地震工程与结构动力学》1980,8(3):267-273
A simple formula, equation (15), is derived for the peak additional cable tension that can be expected in a suspension bridge undergoing earthquake excitation. The method involves application of the response spectrum technique and rests on several plausible assumptions. The formula gives a reasonable upper bound, suitable for preliminary design estimates, irrespective of whether the ground motions at each end are in-phase or, as is probable with a long span bridge, whether they are out-of-phase. 相似文献