The relationship of elasticity and crystal structure in andalusite and sillimanite     

Michael T. Vaughan  Donald J. Weidner 《Physics and Chemistry of Minerals》1978,3(2):133-144

The nine elastic constants of andalusite and sillimanite have been determined, using the technique of Brillouin scattering. They are, in megabars, for andalusite: c ₁₁=2.334, c ₂₂=2.890, c ₃₃=3.801, c ₄₄=0.995, c ₅₅=0.878, c ₆₆=1.123, c ₂₃=0.977, c ₁₃=1.162, c ₁₂=0.814; for sillimanite: c ₁₁=2.873, c ₂₂=2.319, c ₃₃=3.884, c ₄₄=1.224, c ₅₅=0.807, c ₆₆=0.893, c ₂₃=1.586, c ₁₃=0.834, c ₁₂=0.947. Both structures are characterized by chains of edge-linked coordination octahedra extending parallel to the crystallographic c direction, cross-linked by polyhedra of lower coordination. In each structure the stiffness measured parallel to c is greater than that measured normal to c. The shear moduli can be directly correlated with the relative rigidity of the cross-linking structures.  相似文献   

Thermodynamic properties of almandine-grossular garnet solid solutions   总被引：1，自引：0，他引：1  

G. Cressey  R. Schmid  B. J. Wood 《Contributions to Mineralogy and Petrology》1978,67(4):397-404

The mixing properties of Fe₃Al₂Si₃O₁₂-Ca₃Al₂Si₃O₁₂ garnet solid solutions have been studied in the temperature range 850–1100° C. The experimental method involves measuring the composition of garnet in equilibrium with an assemblage in which the activity of the Ca₃Al₂Si₃O₁₂ component is fixed. Experiments on the assemblage garnet solid solution, anorthite, Al₂SiO₅ polymorph and quartz at known pressure and temperature fix the activity of the Ca₃Al₂Si₃O₁₂ component through the equilibrium: 1 $$\begin{gathered} {\text{3CaAl}}_{\text{2}} {\text{Si}}_{\text{2}} {\text{O}}_{\text{8}} \rightleftarrows {\text{Ca}}_{\text{3}} {\text{Al}}_{\text{2}} {\text{Si}}_{\text{3}} {\text{O}}_{{\text{12}}} \hfill \\ {\text{Anorthite garnet}} \hfill \\ {\text{ + 2Al}}_{\text{2}} {\text{SiO}}_{\text{5}} {\text{ + SiO}}_{\text{2}} \hfill \\ {\text{ sillimanite/kyanite quartz}}{\text{.}} \hfill \\ \end{gathered}$$ This equilibrium, with either sillimanite or kyanite as the aluminosilicate mineral, was used to control \({\text{a}}_{{\text{Ca}}_{\text{3}} {\text{Al}}_{\text{2}} {\text{Si}}_{\text{3}} {\text{O}}_{{\text{12}}} }^{{\text{gt}}} \) . The compositions of the garnet solutions produced were determined by measurement of their unit cell edges. At 1 bar Fe₃Al₂Si₃O₁₂-Ca₃Al₂Si₃O₁₂ garnets exhibit negative deviations from ideality at the Fe-rich end of the series and positive deviations at the calcium end. With increasing pressure the activity coefficients for the Ca₃Al₂Si₃O₁₂ component increase because the partial molar volume of this component is greater than the molar volume of pure grossular. Previous studies indicate that the activity coefficients for the Ca₃Al₂Si₃O₁₂ component also increase with increasing (Mg/Mg+Fe) ratio of the garnet. The region of negative deviation from ideality implies a tendency towards formation of a stable Fe-Ca garnet component. Evidence in support of this conclusion has been found in a natural Fe-rich garnet which was found to contain two different garnet phases of distinctly different compositions.  相似文献   

Capital investment and regional planning in Britain     

P.A. Wood 《Geoforum》1974,5(3):19-27

British regional problems increasingly emphasize the need to understand the exploitation and movement of all factors of production between different parts of the country. This paper reviews evidence, from work sponsored by the National Institute of Economic and Social Research, on the significance for the standard regions of capital investment, interregional capital flows and regional investment multipliers. A high level of economic interdependence allows the effects of investment to become widely spread throughout the British space economy. This limits the power of capital expenditure to lead growth in the region where it takes place. Studies of the spatial implications of capital investment should therefore form part of more general appraisals of factor supply and demand changes and their effects on the decisions of different investing agencies (including government). Two distinctive themes for the geographical study of capital investment are suggested: the examination of relationships between investment projects by different agencies at appropriate sub-regional scales; and the ways in which established patterns of physical capital stock may influence the expenditure of new, mobile funds.  相似文献   

New views of the Moon,edited by Bradley L. Jolliff,Mark A. Wieczorek,Charles K. Shearer,and Clive R. Neal     

Charles A. Wood 《Meteoritics & planetary science》2007,42(2):303-304

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GLAST large area telescope multiwavelength planning     

O. Reimer  P. F. Michelson  R. A. Cameron  S. W. Digel  D. J. Thompson  K. S. Wood 《Astrophysics and Space Science》2007,309(1-4):523-526

Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.   相似文献   

Salinograph trends as indicators of the recession characteristics of stream components     

A. D. Werner  M. Wood  C. T. Simmons  D. A. Lockington 《水文研究》2008,22(16):3020-3028

Compared to hydrograph recession analysis, which is widely applied in engineering hydrology, the quantitative assessment of stream salinity with time (i.e. the salinograph) has received significantly less attention. In particular, while in many previous hydrological studies an inverse relationship between hydrograph and salinograph responses is apparent, the concept of salinity accession (the inversely related salinity counterpart to hydrograph recession) has not been introduced nor quantitatively evaluated in previous literature. In this study, we conduct a mathematical analysis of salinograph accession, and determine new quantitative relationships between salinity accession and hydrograph recession parameters. An equation is formulated that reproduces the general trend in salinity accession. A salinity accession parameter k_c is then introduced and is shown to be the ratio of direct runoff to total stream flow recession parameters: k_r/k. The groundwater recession parameter k_g was estimated using a simple and rapid method that uses both salinograph and hydrograph data. Salinity accession type‐curves illustrate that under certain conditions, the relative steepness of individual salinographs is dependent upon the ratio of groundwater salinity to direct runoff salinity: C_g/C_r. The salinity accession algorithms are applied to two contrasting field settings: Scott Creek, South Australia and Sandy Creek, northern Queensland, Australia. It was found that k_g > k during periods of obvious stream flow recession, for the events analysed. Salinograph accession behaviour was fairly similar for both sites, despite contrasting environments. Using assumed end‐member salinities for groundwater and direct runoff based upon field observations, the behaviour of k_c from the Scott Creek site was approximately reproduced by varying the initial groundwater to runoff flow ratio: Q_g0/Q_r0, within reasonable parameter ranges. The use of salinograph information when used in addition to standard hydrograph analyses provided useful information on recession characteristics of stream components. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Hydroecology and ecohydrology: a potential route forward?     

David M. Hannah  Jonathan P. Sadler  Paul J. Wood 《水文研究》2007,21(24):3385-3390

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The amazing world of James Hector – Edited by Simon Nathan and Mary Varnham     

Vaughan Wood 《New Zealand geographer》2009,65(3):236-237

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Abundances in intermediate-mass AGB stars undergoing third dredge-up and hot-bottom burning     

J. A. McSaveney  P. R.Wood  M. Scholz  J. C. Lattanzio  K. H. Hinkle 《Monthly notices of the Royal Astronomical Society》2007,378(3):1089-1100

High-dispersion near-infrared spectra have been taken of seven highly evolved, variable, intermediate-mass (4–6 M_⊙) asymptotic giant branch (AGB) stars in the Large Magellanic Cloud and Small Magellanic Cloud in order to look for C, N and O variations that are expected to arise from third dredge-up and hot-bottom burning. The pulsation of the objects has been modelled, yielding stellar masses, and spectral synthesis calculations have been performed in order to derive abundances from the observed spectra. For two stars, abundances of C, N, O, Na, Al, Ti, Sc and Fe were derived and compared with the abundances predicted by detailed AGB models. Both stars show very large N enhancements and C deficiencies. These results provide the first observational confirmation of the long-predicted production of primary nitrogen by the combination of third dredge-up and hot-bottom burning in intermediate-mass AGB stars. It was not possible to derive abundances for the remaining five stars: three were too cool to model, while another two had strong shocks in their atmospheres which caused strong emission to fill the line cores and made abundance determination impossible. The latter occurrence allows us to predict the pulsation phase interval during which observations should be made if successful abundance analysis is to be possible.  相似文献   

The energy balance over land and oceans: an assessment based on direct observations and CMIP5 climate models   总被引：2，自引：0，他引：2  

Martin Wild  Doris Folini  Maria Z. Hakuba  Christoph Schär  Sonia I. Seneviratne  Seiji Kato  David Rutan  Christof Ammann  Eric F. Wood  Gert König-Langlo 《Climate Dynamics》2015,44(11-12):3393-3429

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