Tertiary systems     

Alan G. Hernried  Jerome L. Sackman 《地震工程与结构动力学》1985,13(4):467-479

Through perturbation theory, results are obtained for the dynamic response of the very light equipment component(s) of tertiary equipment-structure systems. Both the three-degree-of-freedom and multi-degree-of-freedom models are examined. The case of all natural frequencies of the subsystems distinct (detuning) as well as a natural frequency of each subsystem close or equal to one another (tuning) are examined. The results should serve as a reliable and economical alternative to expensive numerical time-integration schemes which may mask significant response due to ill-conditioning of the combined system property matrices.  相似文献   

Distribution and isotopic composition of sulfur in lake sediments of northern Ontario   总被引：1，自引：0，他引：1  

Jerome O. Nriagu  Yoong K. Soon 《Geochimica et cosmochimica acta》1985,49(3):823-834

Sediments from unpolluted and highly polluted lakes in northern Ontario have been fractionated into acid volatile sulfide, HCl-soluble sulfur, elemental sulfur, pyrite sulfur, ester sulfate and carbon-bonded sulfur and the isotopic composition of each fraction determined. In general, reduced inorganic S constitutes 25–50% of the total S in the polluted surficial sediments, but is <20% in the unpolluted samples, with pyrite formation being a minor process of S diagenesis in lake sediment ecosystems. Organic S in the form of ester sulfate and carbon-bonded S predominates and both the C/S ratios and the isotopic data suggest that, in unpolluted lakes, plant detritus can be a major contributor of organic-S to the sediments. The depth profiles observed suggest that the more labile ester sulfate is diagenetically converted to the carbon-bonded form. For the polluted sediments from the Sudbury basin, the isotopic data suggest that (a) the elemental S is derived from the oxidation of acid volatile sulfide in the aerobic surficial sediments, and (b) the isotopically light reduced S species are incorporated into the organic material. S diagenesis in lake sediments generally results in the release of ³⁴S to the overlying water. The suggestion is made that sulfate concentrations over 5 mg/1 accompanied by an enrichment of surficial sediments with isotopically different S may signal significant inputs of pollutant S into the lake and its basin.  相似文献   

Some methods for the analysis of equipment-structure interaction     

Tim J. Ingham  Jerome L. Sackman 《地震工程与结构动力学》1984,12(5):583-601

We present some numerical methods which simplify the analysis of equipment-structure systems composed of an equipment component which is light with respect to the structure component. We consider completely general forms of equipment-structure interaction. In particular, we consider that an arbitrary number of natural frequencies of the equipment and the structure are nearly equal (or equal) to each other. We show that this coincidence of natural frequencies implies that the equipment-structure system will itself have several closely spaced natural frequencies. The essence of equipment-structure interaction is the formation of beats, with slowly varying amplitude in each degree of freedom, between these natural frequencies-at least in response to a δ-function ground motion. We derive some differential equations, the solutions of which are a slowly varying envelope function (a vector) which yields the above slowly varying amplitudes. It is obtained by numerical integration using some conventional, but modified, methods and using a step size appropriate to capture its slowly varying nature. This envelope function defines the response to a δ-function ground motion. We show how it may be combined with the properties of an arbitrary ground motion (acceleration record or response spectrum) to yield the response to such a ground motion.  相似文献   

Ionospheric reflection coefficients at vlf from sferics measurements     

A. Glenn Jean Jr.  L. Jerome Lange  James R. Wait 《Pure and Applied Geophysics》1957,38(1):147-153

Summary A method for calculating the complex ionospheric reflection coefficients at vlf using sferic waveforms is presented. The mathematical analysis was carried out for a number of different waveforms to illustrate the method. Reflection coefficients determined from sferics observations were compared with those calculated using an ionospheric model. In most cases, the agreement with theory is fairly good although in some cases, reflection coefficients exceeding unity were obtained. The discrepancies are believed to result from horizontally polarized flashes rather than limitations in the ionospheric model.  相似文献   

Coronal hole evolution by sudden large scale changes     

Jerome T. Nolte  Michel Gerassimenko  Allen S. Krieger  Craig V. Solodyna 《Solar physics》1978,56(1):153-159

We have compared sudden shifts in coronal hole boundaries observed by the S-054 X-ray telescope on Skylab between May and November, 1973, within 1 day of CMP of the holes, at latitudes 40 °, with the long-term evolution of coronal hole area. We find that large-scale shifts in boundary locations can account for most if not all of the evolution of coronal holes. The temporal and spatial scales of these large-scale changes imply that they are the results of a physical process occurring in the corona. We conclude that coronal holes evolve by magnetic field lines opening when the holes are growing, and by fields closing as the holes shrink.Skylab Solar Workshop post-doctoral appointee 1975–1976. The Skylab Solar Workshops are sponsored by NASA and NSF and managed by the High Altitude Observatory, National Center for Atmospheric Research.  相似文献   

The First Quantitative Slip-Rate Estimated Along the Ashikule Fault at the Western Segment of the Altyn Tagh Fault System     

PAN Jiawei  LI Haibing  VAN DER WOERD Jerome  SUN Zhiming  SI Jialiang  PEI Junling  WU Fuyao  CHEVALIER Marie-Luce 《《地质学报》英文版》2015,89(6):2088-2089

<正>As one of the longest strike-slip fault in Asia,the Altyn Tagh Fault(ATF)defines the northern boundary of the Tibetan Plateau and plays a significant role inaccommodating the deformation resulting from the IndiaAsia convergence.Slip-rate and seismic behavior of the fault are critical to understand the present-day kinematics  相似文献   

Initiation and Propagation of Compaction Bands in Dry and Wet Bentheim Sandstone     

Sergei Stanchits  Jerome Fortin  Yves Gueguen  Georg Dresen 《Pure and Applied Geophysics》2009,166(5-7):843-868

We investigated initiation and propagation of compaction bands (CB) in six wet and four dry Bentheim sandstone samples deformed in axial compression tests with strain rates ranging from 3.2 × 10^?8 s^?1 to 3.2 × 10^?4 s^?1. Circumferential notches with 0.8-mm width and 5-mm depth served to initiate CB at mid-sample length. Wet samples were saturated with distilled water and deformed at 195 MPa confining pressure and 10 MPa pore pressure. Dry samples were deformed at 185 MPa confining pressure. Twelve P-wave sensors, eight S-wave sensors and two pairs of orthogonally oriented strain-gages were glued to the sample surface to monitor acoustic emission (AE), velocities and local strain during the loading process. Nucleation of compaction bands is indicated by AE clusters close to the notch tips. With progressive loading, AE activity increased and AE hypocenters indicated propagation of a single CB normal to the sample axis. CB propagation from the sample periphery towards the centre was monitored. Microstructural analysis of deformed samples shows excellent agreement between location of AE clusters and CBs. In both dry and wet samples the lateral propagation of CBs was about 100 times faster than axial shortening rates. At the slowest displacement rate, AE activity during band propagation was reduced and CB nucleation in wet samples occurred at 20% lower stresses. This may indicate an increasing contribution of stress corrosion processes to the formation of the compaction bands. In dry and wet samples inelastic compaction energy per area ranged between 16 and 80 kJ m^?2. This is in good agreement with previous estimates from laboratory and field studies.  相似文献   

Chemical weathering and CO2 consumption rate in a multilayered‐aquifer dominated watershed under intensive farming: The Orgeval Critical Zone Observatory,France     

Paul Floury  Jrme Gaillardet  Gaëlle Tallec  Patrick Ansart  Julien Bouchez  Pascale Louvat  Caroline Gorge 《水文研究》2019,33(2):195-213

The impact of intensive farming on chemical weathering in the Critical Zone is still an open question. Extensively instrumented and monitored over the last 50 years, the Orgeval Critical Zone Observatory (CZO) in France is an observation site impacted by intensive farming since the 1960s. The Orgeval observatory represents an ideal place to study the response and resilience capability of the Critical Zone under agricultural stress. This paper investigates the chemical composition of different water bodies in two nested catchments of the Orgeval CZO, including rainfall, springs, rivers, and rocks, over one and half hydrological year. We show that elemental and strontium isotopic ratios are powerful to constrain the origin of the elements. The results show that the river chemistry at the outlet of the two nested catchments is dominated by rain inputs (particularly atmospheric dust dissolution) and the chemical weathering of limestone and gypsum. Fertilizer input is clearly visible, although the distinction between gypsum dissolution and fertilizer inputs needs more investigation. The mixtures of water masses inferred from our data are in good agreement with the hydrological context of the watershed, that is, a multilayered aquifer structure. At the main outlet of the CZO, we estimate that the input of ocean‐derived solutes through rainfall represents 7 t km^?2 year^?1, on the same order of magnitude as the net fertilizer input (10 t km^?2 year^?1), and that rock weathering releases 50 t km^?2 year^?1. Including previously published physical erosion rates, we estimate that the total denudation rate (physical and chemical) of the Orgeval CZO is 20 mm (1,000 year)^?1, which, along with the entire Seine watershed, is among the lowest chemical denudation rates for carbonate terrains under temperate climate. Chemical denudation is about 10 times higher than physical erosion in the Orgeval CZO. The consumption of CO₂ by rock weathering is estimated to be between 265.10³ and 360.10³ molC km² year^?1, similar for the two nested catchments. Compared with the rivers, the springs show a higher CO₂ consumption rate that suggests, as pointed out earlier, a enhancement of carbonate dissolution linked to nitrification and thus fertilizer application. The hyporheic zone appears to be a hot spot in the carbon cycle at the Orgeval CZO. This study sheds light on the complex, anthropocenic, interplay between geology, climate, and human activities that characterize and that take place in intensive agriculture regions.  相似文献   

Zn isotopes in the suspended load of the Seine River, France: Isotopic variations and source determination   总被引：1，自引：0，他引：1  

JiuBin Chen  Jérôme Gaillardet  Sylvain Huon 《Geochimica et cosmochimica acta》2009,73(14):4060-783

We report Zn isotopic ratios (δ⁶⁶Zn) of river suspended particulate matter (SPM) and floodplain deposits (FD) from the Seine basin, France, with a precision ?0.05‰. A decrease in δ⁶⁶Zn from 0.30‰ to 0.08‰ is observed in SPM from the upstream to downstream parts of the fluvial system, associated with an increase in Zn concentration from 100 ppm to 400 ppm. The Zn/Al of SPM at the river mouth is up to five times greater than the Zn/Al of the natural background, and by normalizing to the later value we define a Zn enrichment factor. Suspended sediments from a temporal series of samples collected in Paris display a similar variation in δ⁶⁶Zn of between 0.08‰ and 0.26‰, while showing an inverse relationship between the Zn enrichment factor and δ⁶⁶Zn. The amount of Zn transported as suspended load varies from 10% to 90%, as a function of increasing discharge. The δ⁶⁶Zn of SPM and the dissolved load are correlated, suggesting that adsorption processes are probably not the dominant process by which the Zn enrichment of SPM takes place. Instead, we interpret our data as reflecting the mixture of two main populations of suspended particles with distinct δ⁶⁶Zn. The first is characteristic of natural silicate particles transported by erosion processes to the river, while the second likely represents anthropogenic particles derived from wastewater treatment plants or combined sewer overflows. Based on isotopic ratios, we calculate that 70% of Zn in SPM of the Seine River in Paris is of anthropogenic origin.  相似文献   

The effect of silica and natural organic matter on the Fe(II)-catalysed transformation and reactivity of Fe(III) minerals   总被引：3，自引：0，他引：3  

Adele M. Jones  Jerome Rose 《Geochimica et cosmochimica acta》2009,73(15):4409-4422

The Fe(II)-catalysed transformation of synthetic schwertmannite, ferrihydrite, jarosite and lepidocrocite to more stable, crystalline Fe(III) oxyhydroxides is prevented by high, natural concentrations of Si and natural organic matter (NOM). Adsorption isotherms demonstrate that Si adsorbs to the iron minerals investigated and that increasing amounts of adsorbed Si results in a decrease in isotope exchange between aqueous Fe(II) and the Fe(III) mineral. This suggests that the adsorption of Si inhibits the direct adsorption of Fe(II) onto the mineral surface, providing an explanation for the inhibitory effect of Si on the Fe(II)-catalysed transformation of Fe(III) minerals. During the synthesis of lepidocrocite and ferrihydrite, the presence of equimolar concentrations of Si and Fe resulted in the formation of 2-line ferrihydrite containing co-precipitated Si in both cases. Isotope exchange experiments conducted with this freeze-dried Si co-precipitated ferrihydrite species (Si-ferrihydrite) demonstrated that the rate and extent of isotope exchange between aqueous Fe(II) and solid ⁵⁵Fe(III) was very similar to that of 2-line ferrihydrite formed in the absence of Si and which had not been allowed to dry. In contrast to un-dried ferrihydrite formed in the absence of Si, Si-ferrihydrite did not transform into a more crystalline Fe(III) mineral phase over the 7-day period of investigation. Reductive dissolution studies using ascorbic acid demonstrated that both dried Si-ferrihydrite and un-dried 2-line ferrihydrite were very reactive, suggesting these species may be major contributors to the rapid release of dissolved iron following flooding and the onset of conditions conducive to reductive dissolution in acid sulphate soil environments.  相似文献