An extrusion energy absorber suitable for the protection of structures during an earthquake     

W. H. Robinson  L. R. Greenbank 《地震工程与结构动力学》1976,4(3):251-259

A structure moving under the influence of an earthquake is normally required to absorb its own energy of motion. However, in many cases it is possible to attach to the structure energy absorbing devices which absorb most of its energy of motion. One such device is an energy absorber which works by extruding lead back and forth through an orifice. On being extruded the deformed lead recrystallizes immediately, thereby recovering its original mechanical properties before the next extrusion or stroke. Accordingly, the amount of energy absorbed is not limited by work hardening or fatigue of the lead, but rather by the heat capacity of the device, the melting point of lead being the upper limit to the operating temperature. Furthermore, the device is able to absorb energy during a large number of earthquakes. A number of 20 kN × 2 cm stroke to 200 kN × 26 cm stroke extrusion energy absorbers have been tested at rates of 10^?6 to 3.6 × 10^?6 cm/min. They behaved as ‘plastic solids’ or ‘coulomb dampers’ with nearly rectangular hysteresis loops and little rate dependence.  相似文献   

Magma fractionation systems beneath the mid-Atlantic ridge at 36–37 ° N     

M. F. J. Flower  P. T. Robinson  H. -U. Schmincke  W. Ohnmacht 《Contributions to Mineralogy and Petrology》1977,64(2):167-195

Variation of major and trace elements in drilled basalts from the Mid-Atlantic Ridge (DSDP Leg 37) reflects distinct cycles of low pressure fractionation operating independently within a complex network of magma storage reservoirs beneath the crustal spreading axis. Low pressure phase relations are determined by parental magma composition, which varies from An-rich (An/Di > ca. 1.4) to Di-rich (An/Di < ca. 1.4). High An/Di magmas probably formed under slightly hydrous conditions in the mantle. They have low LIL element contents, low P/Y and high Mg/(Mg + Fe) ratios. Zr, P and Y abundance and inter-element ratios are highly diagnostic of primary magma type, and are used to quantify fractional crystallization models.Low pressure fractionation hypotheses were tested by least-squares modelling of whole-rock and phenocryst chemistry, which indicated removal or addition of phenocryst assemblages: ol; pl; ol + pl; ol + pl + cpx; pl + cpx, (± sp). Accumulation of plagioclase or olivine is an important mechanism for generating highly porphyritic rocks. A rare 3-phase (ol + pl + cpx) cumulate resulted from cotectic fractionation of a low An/Di magma type. Olivine and plagioclase cumulates appear to be related to high An/Di magmas. Olivine accumulation has been monitored by comparison of olivine/bulk rock partitioning of Fe and Mg to experimental measurements of the equilibrium K_D value. A single extensive sub-axial magma chamber could not account for the observed chemical variation and would probably be dynamically unstable.  相似文献   

Assessment of δ13C and C/N ratios in bulk organic matter as palaeosalinity indicators in Holocene and Lateglacial isolation basin sediments,northwest Scotland     

Elizabeth A. V. Mackie  Jeremy M. Lloyd  Melanie J. Leng  Michael J. Bentley  Carol Arrowsmith 《第四纪科学杂志》2007,22(6):579-591

Carbon isotopes (δ¹³C) and C/N ratios from bulk organic matter have recently been used as alternative proxies for relative sea‐level (RSL) reconstruction where there are problems associated with conventional biological indictors. A previous study on a single isolation basin (Upper Loch nan Eala) in northwest Scotland has shown a clear relationship between δ¹³C, C/N ratios and palaeosalinity from Younger Dryas and Holocene aged sediments. In this paper we present results of δ¹³C and C/N ratio analyses from other isolation basins in northwest Scotland over the Holocene and the Lateglacial period in order to validate this technique. The results from the Holocene sequences support the earlier findings that this technique can be used to identify RSL change from isolation basins over the Holocene in this region. The relationship between δ¹³C, C/N ratios and RSL change is not apparent in sediments of Lateglacial age. Other environmental variables such as atmospheric CO₂ concentration, poor vegetation development and temperature influence δ¹³C values during this period. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Heavy metal release by peat erosion in the Peak District,southern Pennines,UK     

J. J. Rothwell  S. G. Robinson  M. G. Evans  J. Yang  T. E. H. Allott 《水文研究》2005,19(15):2973-2989

Upper North Grain (UNG) is a heavily eroding blanket peat catchment in the Peak District, southern Pennines, UK. Concentrations of lead in the near‐surface peat layer at UNG are in excess of 1000 mg kg⁻¹. For peatland environments, these lead concentrations are some of the highest globally. High concentrations of industrially derived, atmospherically transported magnetic spherules are also stored in the near‐surface peat layer. Samples of suspended sediment taken during a storm event that occurred on 1 November 2002 at UNG, and of the potential catchment sources for suspended sediments, were analysed for lead content and the environmental magnetic properties of anhysteretic remanent magnetization (ARM) and saturation isothermal remanent magnetization (SIRM). At the beginning of the storm event, there is a peak in both suspended sediment and associated lead concentration. SIRM/ARM values for suspended sediment samples throughout the storm reveal that the initial ‘lead flush’ is associated with a specific sediment source, namely that of organic sediment eroded from the upper peat layer. Using the magnetic ‘fingerprinting’ approach to discrimination of sediment sources, this study reveals that erosion of the upper peat layer at UNG is releasing high concentrations of industrially derived lead (and, by inference, other toxic heavy metals associated with industrial particulates) into the fluvial systems of the southern Pennines. Climate‐change scenarios for the UK, involving higher summer temperatures and stormier winters, may result in an increased flux both of sediment‐associated and dissolved heavy metals from eroding peatland catchments in the southern Pennines, adversely affecting the quality of sediment and water entering reservoirs of the region. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Coupled HM analysis using zero‐thickness interface elements with double nodes—Part II: Verification and application     

J. M. Segura  I. Carol 《国际地质力学数值与分析法杂志》2008,32(18):2103-2123

In a companion Part I of this paper (Int. J. Numer. Anal. Meth. Geomech. 2008; DOI: 10.1002/nag.735 ), a coupled hydro‐mechanical (HM) formulation for geomaterials with discontinuities based on the finite element method (FEM) with double‐node, zero‐thickness interface elements was developed and presented. This Part II paper includes the numerical solution of basic practical problems using both the staggered and the fully coupled approaches. A first group of simulations, based on the classical consolidation problem with an added vertical discontinuity, is used to compare both the approaches in terms of accuracy and convergence. The monolithic or fully coupled scheme is also used in an application example studying the influence of a horizontal joint in the performance of a reservoir subject to fluid extraction. Results include a comparison with other numerical solutions from the literature and a sensitivity analysis of the mechanical parameters of the discontinuity. Some simulations are also run using both a full non‐symmetric and a simplified symmetric Jacobian matrix. On top of verifying the model developed and its capability to reflect the conductivity changes of the interface with aperture changes, the results presented also lead to interesting observations of the numerical performance of the methods implemented. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

On the effects of coherent structures on higher order moments in models of solar and stellar surface convection     

F. Kupka  F. J. Robinson 《Monthly notices of the Royal Astronomical Society》2007,374(1):305-322

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National defense applications of autonomous underwater vehicles     

Robinson  R. 《Oceanic Engineering, IEEE Journal of》1986,11(4):462-467

During the 1982 invasion of southern Lebanon, the Israeli Air Force faced the problem of neutralizing the massive Syrian air defense network in the Bekka Valley as a step in gaining air control in the area. They accomplished this, in a matter of days, without the loss of a single aircraft, while inflicting a loss of over 80 aircraft on the Syrian Air Force. The key to this smashing tactical success was the tactic used to suppress the extensive air defense network. The Israelis used remotely piloted vehicles (RPV's) for the high-risk elements of their tactical plan. RPV's conducted in-depth reconnaissance to spot and fingerprint the search and fire control radars in the valley and on adjacent mountainsides and to locate surface-to-air missile (SAM) launch sites. When the attack started, the first waves were RPV's configured to appear as attack aircraft and draw first fire. As the engagement started, manned attack fighter-bombers used antiradiation missiles (ARM's) and other smart ordnance to destroy enemy radars and launch sites as they were engaging the RPV's. While there was some loss of the low-cost RPV's, there were no losses to the Israeli aircraft. A "hornet's nest" of weapons and radars had been effectively neutralized without loss and in a period of a few hours. Recent statements of current U.S. Naval doctrine [1] emphasize a forward area strategy of naval action in or near enemy waters. The Soviet Navy in turn has been attributed as having a "bastion" strategy [2] to operate their SLBM force in Arctic waters and heavily defend the sea approaches to these waters. In other words, we postulate that they will create a "hornet's nest" and the U.S. Navy would intend to attack it, a Naval "Bekka Valley." This article examines the potential need for unmanned systems in the execution of the forward-area strategy. Emphasis is upon medium- and long-range submersibles capable of autonomous operation.  相似文献   

The relation between flare-related metric continuum bursts and coronal mass ejections     

R. D. Robinson 《Solar physics》1986,103(1):33-39

We describe a simple irradiance monitor intended for use in assessing the suitability of candidate sites for a worldwide network of small solar telescopes. The network will observe the Sun as continuously as possible in order to provide high quality solar oscillation data with low diurnal sidelobe contamination and high temporal frequency resolution.Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation.  相似文献   

Informed selection of future climates     

Channing Arndt  Charles Fant  Sherman Robinson  Kenneth Strzepek 《Climatic change》2015,131(1):21-33

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Detecting infiltration and impacts of introduced water using strontium isotopes   总被引：3，自引：0，他引：3  

Brinck EL  Frost CD 《Ground water》2007,45(5):554-568

Water introduced to surface drainages, such as agricultural and roadway runoff, mine drainage, or coalbed natural gas (CBNG)-produced water, potentially can be of environmental concern. In order to mitigate potential environmental effects, it may be important to be able to trace water discharged to the surface as it infiltrates and interacts with near-surface aquifers. We have chosen to study water withdrawn during CBNG production for isotope tracing in the hyporheic zone because it poses a variety of economic, environmental, and policy issues in the Rocky Mountain states. Ground water quality must be protected as CBNG water is added to semiarid ecosystems. Strontium (Sr) isotopes are effective fingerprints of the aquifer from which water originates. In this study, CBNG water was found to have a higher (87)Sr/(86)Sr ratio than the local alluvial aquifer water. This measurable difference allows the strontium isotope ratio and concentration to be used as tracers of CBNG water following its discharge to the surface. The dissolution and mobilization of salts from soil are an important contributor to ground water quality degradation. In the Powder River basin of Wyoming, the soils are calcium carbonate-buffered systems. The chemical similarity of strontium to calcium allows it to substitute into calcium minerals and enabled us to use strontium isotopes to identify calcium salts mobilized from the soil. Strontium isotopes are an effective monitor of the source of ions and the volume and direction of introduced water flow in the hyporheic zone.  相似文献