The Preservation of Historic Buildings in Urban New Zealand: Precedent,Practice and Policy1     

P. J. Perry  K. Galletly 《New Zealand geographer》1984,40(2):100-104

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Towards a Political Geography of Corruption     

Peter Perry 《New Zealand geographer》1985,41(1):2-7

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Syn-depositional alteration of coral reef framework through bioerosion,encrustation and cementation: Taphonomic signatures of reef accretion and reef depositional events     

C.T. Perry  L.J. Hepburn 《Earth》2008,86(1-4):106-144

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Iterative approach to groundwater flow modeling of the Martinsville Alternative Site,under consideration for low-level radioactive waste storage in Clark County,Illinois, U.S.A.     

Thomas C. Beard  Christopher J. Perry  Tad C. Fox  Thomas G. Naymik  Peter Shanahan 《Environmental Geology》1991,18(3):195-207

The regulatory requirements for characterization of the Martinsville Alternative Site (MAS) were fulfilled by applying an iterative approach to the groundwater flow modeling of the site and surrounding area. The approach consisted of field data collection and development of an initial conceptual model. The numerical model was then constructed to be consistent with the data and conceptual model. Next, the calibration results were evaluated statistically, and visually by a groundwater modeling review committee, to determine if the model accurately represented groundwater flow at the site. Initial results failed acceptance criteria because the values of numerical model input parameters had to be varied beyond observed data ranges to calibrate the results, and therefore the model was inconsistent with the initial conceptual model. This led to additional field data collection in areas where the numerical model deviated most from field-determined data. The new data provided sufficient information to revise the conceptual model and calibrate the numerical model successfully. Model calibration was followed by validation. Validation of the numerical model provided additional assurance that the model correctly simulated the observed system. No additional data were found to be necessary during validation of the MAS numerical model. The iterative approach proved to be successful for calibrating and validating this groundwater flow model and should be implemented from the onset of characterization planning in other applications.  相似文献   

A Field Evaluation of In-Situ Biodegradation of Chlorinated Ethenes: Part 2, Results of Biostimulation and Biotransformation Experiments   总被引：2，自引：0，他引：2  

Lewis Semprini  Paul V. Roberts  Gary D. Hopkins  Perry L. McCarty 《Ground water》1990,28(5):715-727

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The relation between dilatancy,effective stress and dispersive pressure in granular avalanches     

Perry Bartelt  Othmar Buser 《Acta Geotechnica》2016,11(3):549-557

Here we investigate three long-standing principles of granular mechanics and avalanche science: dilatancy, effective stress and dispersive pressure. We first show how the three principles are mechanically interrelated: Shearing of a particle ensemble creates a mechanical energy flux associated with random particle movements (scattering). Because the particle scattering is inhibited at the basal boundary, there is a spontaneous rise in the center of mass of the particle ensemble (dilatancy). This rise is connected to a change in potential energy. When the center of mass rises, there is a corresponding reaction at the base of the flow that is coupled to the vertical acceleration of the ensemble. This inertial stress is the dispersive pressure. Dilatancy is therefore not well connected to effective-stress-type relations, rather the energy fluxes describing the configurational changes of the particle ensemble. The strict application of energy principles has far-reaching implications for the modeling of avalanches and debris flows and other dangerous geophysical hazards.  相似文献   

Sub-regional snow cover distribution across the southern Appalachian Mountains     

Johnathan W. Sugg  Christopher M. Fuhrmann  L. Baker Perry  Dorothy K. Hall  Charles E. Konrad II 《自然地理学》2017,38(2):105-123

Abstract

Snowfall in the Southern Appalachian Mountain region of the eastern US is characterized by much spatiotemporal variability. Annual snowfall totals vary by up to 75 cm, and variations in snowfall intensity can lead to large differences in the local snowfall distribution. Research has shown that the synoptic pattern associated with the snowfall strongly influences the regional-scale distribution of snow cover. However, topographic variability results in locally complex snow cover patterns that are not well understood or documented. In this study, we characterize the snow covered area (SCA) and fractional snow cover associated with different synoptic patterns in 14 individual sub-regions. We analyze 63 snow events using Moderate-resolution Imaging Spectroradiometer standard snow cover products to ascertain both qualitative and quantitative differences in snow cover across sub-regions. Among sub-regions, there is significant variation in the snow cover pattern from individual synoptic classes. Furthermore, the percent SCA follows the regional snowfall climatology, and sub-regions with the highest elevations and northerly latitudes exhibit the greatest variability. Results of the sub-regional analysis provide valuable guidance to forecasters by contributing a deeper understanding of local snow cover patterns and their relationship to synoptic-scale circulation features.  相似文献   

The effects of diagenesis on the redistribution of strontium isotopes in shales     

Edward A. Perry  Karl K. Turekian 《Geochimica et cosmochimica acta》1974,38(6):929-935

The rubidium-strontium method has often been used in attempts to date shales, but has yielded mixed results. In order to explore the effects of diagenesis on this system, samples of a Miocene shale section collected from an oil well drilled in coastal Louisiana were separated into fractions and analyzed for Sr⁸⁷/Sr⁸⁶, Rb and Sr. The diagenetic changes involve the destruction of detrital mica and feldspar and the formation of an illite-rich clay from smectite. Strontium from interstitial waters, calcium carbonate and adsorbed on the clay minerals is released and then sequestered by the newly forming phases, together with the strontium mobilized from the silicate minerals. Attending these changes there is a trend towards the homogenization of the shale with respect to its strontium isotopes, but diagenesis and homogenization are not complete in the deepest part (5523 m) of the section studied. Therefore, the interpretation of rubidium-strontium shale dates remains uncertain, but the dates in many cases most probably represent the time equal to or younger than the time of the major construction of new phases and the attendant homogenization of the strontium isotopes.  相似文献   

Semiperiodic variations in CO₂ abundance on Venus     

Edwin S. Barker  Michael A. Perry 《Icarus》1975,25(2):282-295

Photoelectric spectral scans of the P branch of the 8689 Å CO₂ band on Venus were made using the 107-inch coude scanner during seven observing periods in the past 2 years. The relative CO₂ line strength was determined for each scan, then normalized to remove the spatial variations leaving only temporal variations.The 4-day periodicity in the relative CO₂ line strength noted by Young et al. (1973) is not unique; we do confirm their 4-day periodicity in August 1973. Four other observing periods rule out a 4-day periodicity.A definite North-South asymmetry in the relative CO₂ line strength is noted during 1973, in most cases with the same periodicity present in both hemispheres. When the slit positions are referred to the equator of Venus, particularly near inferior conjunction, the large asymmetrics between the slit positions can be explained by a greater CO₂ line strength over the polar regions and weaker over the equatorial latitudes. The amplitude of variation of each position on the crescent is much greater near inferior conjunction either because we are sampling a smaller area on the planet or because the upper atmospheric abundance is more sensitive to the mechanism causing the variation in the smaller regions sampled at inferior conjunction.Simultaneous H₂O measurementsduring several of the observing runs indicate a lack of correlation in the relative CO₂ line strengths and the H₂O abundance.  相似文献   

Refining P nuclear magnetic resonance spectroscopy for marine particulate samples: Storage conditions and extraction recovery     

Barbara J. Cade-Menun  Claudia R. Benitez-Nelson  Perry Pellechia  Adina Paytan 《Marine Chemistry》2005,97(3-4):293-306

Solution ³¹P nuclear magnetic resonance (NMR) spectroscopy has recently been used to characterize phosphorus species within marine particles. However, the effects of sample collection, storage and preparation have not been thoroughly examined. In this study, samples of settling particulates collected from a 1200-m sediment trap located in Monterey Bay, California, were subjected to various storage options (i.e., no storage, refrigeration, freezing, and oven-drying and grinding) prior to extraction for solution ³¹P-NMR spectroscopy. Freezing, refrigerating and drying samples for periods of up to 6 months prior to extraction with 0.25 M NaOH + 0.05 M Na₂EDTA increased the concentration of extracted P by an average of 16% relative to samples extracted without storage. Pre-extraction storage also introduced some minor changes in P speciation, by increasing the percentage of orthophosphate by up to 15% and decreasing the percentage of pyrophosphate by up to 5%, relative to the abundances of these P species in samples extracted without storage. Drying caused the biggest changes in speciation, specifically decreasing more extensively the relative percentage of pyrophosphate compared to other treatments. Nevertheless, observed changes in speciation due to sample storage within a specific sample were small relative to differences observed among samples collected sequentially in the same area, or reported differences among samples collected at different locations. Samples were also analyzed by solid-state ³¹P-NMR spectroscopy before and after extraction, to examine extraction-related changes in P speciation. Comparison of solution with solid-state ³¹P NMR indicates that extraction with NaOH–EDTA removes the majority of organic esters, but only a variable portion of phosphonates (39–67%). In addition, there was preferential extraction of Ca-associated phosphate over Mg-, Fe- and Al-associated phosphate. Solution ³¹P NMR enables much higher resolution of P species within samples, particularly when it is important to speciate orthophosphate monoesters and diesters, or if polyphosphates are present. However, combining solid-state ³¹P NMR with solution ³¹P NMR spectroscopy for marine particles should be conducted when examining inorganic P speciation and the abundance of phosphonates.  相似文献