Quick algorithms for computing either displacement,velocity or acceleration of an oscillator     

J. L. Beck  M. J. Dowling 《地震工程与结构动力学》1988,16(2):245-253

Accurate and efficient algorithms are derived for computing any desired response quantity of a single-degree-of-freedom linear oscillator subjected to an arbitrary forcing function. These algorithms are based on linear interpolation of the excitation between discrete points sampled uniformly in time. In the special case of the undamped oscillator, the displacement algorithm is equivalent to a previously published algorithm for this situation which was derived using a finite element approach. However, contrary to the claim made by the authors of this latter algorithm, it does not give an exact solution of the equation of undamped motion for an arbitrary forcing function.  相似文献   

Discussion on a paper by J. L. Beck and M. J. Dowling     

V. W. Lee  J. L. Beck  M. J. Dowling 《地震工程与结构动力学》1988,16(8):1227-1231

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Energy market failure in road transport: Is there scope for ‘no regrets’ greenhouse gas reduction?     

Barry Naughten  Bruce Bowen  Tony Beck 《Climatic change》1993,25(3-4):271-288

The Australian Government policy on reduction of greenhouse gas emissions announced in 1990 includes exploring the scope for immediate, low cost reductions. Such measures can be taken as including ‘no regrets’ policies: those that, in addition to mitigating potential climate change, confer economic gains (including other environmental benefits) which exceed their costs. Some possible ‘no regrets’ opportunities and policies are identified relevant to energy use by the road transport sector over the period to 2020. The MARKALMENSA multi-period linear programming model of the Australian energy sector is used to investigate the cost-effectiveness of these policies.  相似文献   

Preface     

A.E. Beck 《Tectonophysics》1985,121(1):VII-IX

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Eliminierung und Rückgewinnung von Metallionen aus Abwässern — eine Übersicht     

R. Kümmel  F. Winkler  R. Beck 《洁净——土壤、空气、水》1984,12(3):227-237

The present state and the trends of the recovery of heavy metals from wastewaters are presented. The classical precipitation techniques are insatisfactory due to increases of solubility in the presence of impurity ions and/or complexing agents. At present, ion-exchange processes constitute the most frequently used method of metal recycling with an effective enrichment of metal ions. For the effective separation of metals from solutions of a low concentration the electrolytic reduction demands large electrode surface areas. In cells with fixed-bed or fluidized cathodes one can obtain specific electrode surface areas of some 10³ m²/m^m3. For the future, processes of extraction and especially membrane separation will gain in importance. In the past few years, a large number of highly selective metal extracting agents as well as the liquid membrane permeation with suitable carriers were developed. Combinations of membrane separation processes with chemical reactions may attain the same importance, as e.g. ultrafiltration in connection with the fixation of metal ions to watersoluble polymers. In the long run, especially techniques will prevail which will not only result in metal enrichment but also in the recovery of the raw material water.  相似文献   

The Late Maunder Minimum (1675–1715) – A Key Period forStudying Decadal Scale Climatic Change in Europe     

J. Luterbacher  R. Rickli  E. Xoplaki  C. Tinguely  C. Beck  C. Pfister  H. Wanner 《Climatic change》2001,49(4):441-462

The Late Maunder Minimum (LMM, 1675–1715) denotes the climax of the `Little Ice Age' in Europe with marked climate variability. Investigations into interannual and interdecadal differences of atmospheric circulation between the LMM and the period 1961–1990 have been performedand undertaken based upon sea level pressure (SLP) difference maps, empiricalorthogonal function (EOF) analysis, and objective classification techniques. Since the SLP during the LMM winterwas significantly higher in northeastern Europe but below normal over the central and western Mediterranean, more frequent blocking situations were connected with cold air outbreaks towards central and eastern Europe. Springs were cold and characterized by a southward shift of the mid-latitude storm tracks. Summers in western, central Europe and northern Europe were wetter and slightly cooler than they are today due to a weakerAzores high and a more southerly position of the mean polar front axes. Autumns showed a significantly higher pressure over northern Europe and a lower pressure over continental Europe and the Mediterranean, an indication of an advanced change from summer to winter circulation. It is suggested that the pressure patterns during parts of the LMM might be attributed to the combination of external forcing factors (solar irradiance and volcanic activity) and internal oscillations and couplings in the North Atlantic.  相似文献   

LNAPL Retention in Sandy Soil     

David W. Ostendorf  Robin J. Richards  Frank P. Beck 《Ground water》1993,31(2):285-292

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The detection of HCN on Jupiter     

A.T. Tokunaga  S.C. Beck  T.R. Geballe  J.H. Lacy  E. Serabyn 《Icarus》1981,48(2):283-289

We report the detection of HCN on Jupiter. Three R-branch lines of the ν₂ fundamental of HCN near 13.5 μm were observed in absorption, from which the HCN column density is inferred to be 5 × 10^?3 cm-am with an uncertainty of a factor of 2. If emission from the stratosphere exists, then the derived column density is only a lowe limit. We suggest that the Jovian HCN most likely originates from the photolysis of CH₄ and NH₃ in the lower stratosphere and upper troposphere. In addition, an upper limit of 2.5 × 10^?2 cm-am was established for the column density of HCN on Saturn.  相似文献   

Application of matrix analysis in delineating sinkhole risk areas along highway (I-70 near Frederick,Maryland)     

Wanfang?ZhouEmail author  Barry?F.?Beck  Angela?L.?Adams 《Environmental Geology》2003,44(7):834-842

Sinkhole collapse in the area of Maryland Interstate 70 (I-70) and nearby roadways south of Frederick, Maryland, has been posing a threat to the safety of the highway operation as well as other structures. The occurrence of sinkholes is associated with intensive land development. However, the geological conditions that have been developing over the past 200 million years in the Frederick Valley control the locations of the sinkholes. Within an area of approximately 8 km², 138 sinkholes are recorded and their spatial distribution is irregular, but clustered. The clustering indicates the existence of an interaction between the sinkholes. The point pattern of sinkholes is considered to be a sample of a Gibbsian point process from which the hard-core Strauss Model is developed. The radius of influence is calculated for the recorded sinkholes which are most likely to occur within 30 m of an existing sinkhole. The stochastic analysis of the existing sinkholes is biased toward the areas with intensive land use. This bias is adjusted by considering (1) topography, (2) proximity to topographic depressions, (3) interpreted rock formation, (4) soil type, (5) geophysical anomalies, (6) proximity to geologic structures, and (7) thickness of overburden. Based on the properties of each factor, a scoring system is developed and the average relative risk score for individual 30-m segments of the study area is calculated. The areas designated by higher risk levels would have greater risk of a sinkhole collapse than the areas designated by lower risk levels. This risk assessment approach can be updated as more information becomes available.  相似文献   

Reliability of dipole-dipole electrical resistivity tomography for defining depth to bedrock in covered karst terranes     

W. Zhou  B. F. Beck  J. B. Stephenson 《Environmental Geology》2000,39(7):760-766

 Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Because of the irregular distribution of pinnacles and cutters on the bedrock surface, uncertainties arise when "hit-or-miss" borehole drilling is used to locate potential collapse sites. A high-resolution geophysical technique capable of depicting the details of the bedrock surface is essential for guiding the drilling program. Dipole-dipole electrical resistivity tomography (ERT) was used to map the bedrock surface at a site in southern Indiana where limestone is covered by about 9 m of clayey soils. Forty-nine transects were conducted over an area of approximately 42,037 m². The electrode spacing was 3 m. The length of the transects varied from 81 to 249 m. The tomographs were interpreted with the aid of soil borings. The repeatability of ERT was evaluated by comparing the rock surface elevations interpreted from pairs of transects where they crossed each other. The average difference was 2.4 m, with a maximum of 10 m. The discrepancy between interpreted bedrock-surface elevations for a transect intersection may be caused by variations in the subsurface geology normal to the transect. Averaging the elevation data interpreted from different transects improved the ERT results. A bedrock surface map was generated using only the averaged elevation data at the transect junctions. The accuracy of the map was further evaluated using data from four exploratory boreholes. The average difference between interpreted and actual bedrock surface-elevations was less than 0.4 m. The map shows two large troughs in the limestone surface: one coinciding with an existing sinkhole basin, while the other is in alignment with a small topographic valley. Because sinkholes were observed at the same elevation interval in similar valleys in the vicinity, the delineated trough may have implications for future land use at the site. Received: 4 January 1999 · Accepted: 8 March 1999  相似文献