A transformation of the two-body problem     

Victor R. Bond 《Celestial Mechanics and Dynamical Astronomy》1985,35(1):1-7

A transformation of the differential equations of motion of the two-body problem in the spherical coordinates to oscillator form is derived. It is shown that the independent variable transformation dt/ds=r² is a transformation which makes the oscillator form possible.  相似文献   

Real-time difference imaging analysis of MOA Galactic bulge observations during 2000     

I.A. Bond  F. Abe  R.J. Dodd  J.B. Hearnshaw  M. Honda  J. Jugaku  P.M. Kilmartin  A. Marles  K. Masuda  Y. Matsubara  Y. Muraki  T. Nakamura  G. Nankivell  S. Noda  C. Noguchi  K. Ohnishi  N.J. Rattenbury  M. Reid  To. Saito  H. Sato  M. Sekiguchi  J. Skuljan  D.J. Sullivan  T. Sumi  M. Takeuti  Y. Watase  S. Wilkinson  R. Yamada  T. Yanagisawa  P.C.M. Yock 《Monthly notices of the Royal Astronomical Society》2001,327(3):868-880

We describe observations carried out by the MOA group of the Galactic bulge during 2000 that were designed to detect efficiently gravitational microlensing of faint stars in which the magnification is high and/or of short duration. These events are particularly useful for studies of extrasolar planets and faint stars. Approximately 17 deg² were monitored at a sampling rate of up to six times per night. The images were analysed in real time using a difference imaging technique. 20 microlensing candidates were detected, of which eight were alerted to the microlensing community whilst in progress. Approximately half of the candidates had high magnifications (≳10), at least one had very high magnification (≳50), and one exhibited a clear parallax effect. The details of these events are reported here, together with details of the on-line difference imaging technique. Some nova-like events were also observed and these are described, together with one asteroid.  相似文献   

Kinetic studies of lead(II) uptake by the seagrass Zostera muelleri in water by radiotracing,atomic absorption spectrometry and electrochemical techniques     

Alan M Bond  Julie R Bradbury  Henry A Hudson  John S Garnham  Peter J Hanna  Stanley Strother 《Marine Chemistry》1985,16(1):1-9

Evidence was found that uptake of lead from seawater in both model and natural systems by the leaves of the seagrass Zostera muelleri does occur for live, dead and scraped leaves at all the lead concentrations tested. Positive uptake of lead was measured using the three analytical techniques of radio-tracer, differential pulse anodic stripping voltammetry and atomic absorption spectrometry; similar uptake profiles were obtained for each technique. Profiles always showed an initial rapid uptake phase followed by a gradual transition to a plateau phase at which an approximate equilibrium between lead attached to seagrass and free ionic lead in seawater was reached. The presence of active lead uptake processes was indicated in experiments which attempted to remove lead from leaves by a chelating agent.  相似文献   

Effect of element size on the static finite element analysis of steep slopes     

Scott A. Ashford  Nicholas Sitar 《国际地质力学数值与分析法杂志》2001,25(14):1361-1376

The accuracy of the computed stress distribution near the free surface of vertical slopes was evaluated in this study as a function of the element size, including aspect ratio. To accomplish this objective, a parametric study was carried out comparing stresses computed using the finite element method (FEM) to those obtained from a physical model composed of photoelastic material. The results of the study indicate a reasonable agreement between a gelatin model and the FEM model for shear stresses, and an overall good agreement between the two models for the principal stresses. For stresses along the top of the slope, the height of the element tends to be more important than width or aspect ratio, at least for aspect ratios up to 4. In all cases, the greatest difference between the two models occurs in the vicinity of the slope. Specifically, if H is defined as the slope height, an element height of H/10 appears to be adequate for the study of stresses deep within the slope, such as for typical embankment analyses. However, for cases where tensile stresses in the vicinity of the slope face which are critical, such as for the stability analysis of steep slopes, element heights as small as H/32, or higher‐order elements, are necessary. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

The Effect of Atmospheric Drag on Satellite Orbits During the Bastille Day Event     

Knowles  S.H.  Picone  J.M.  Thonnard  S.E.  Nicholas  A.C. 《Solar physics》2001,204(1-2):387-397

Geomagnetic storms driven by solar eruptions are known to have significant effects on the total density of the upper atmosphere in the altitude range 250–1000 km. This in turn causes a measurable effect on the orbits of resident space objects in this altitude range. We analyzed a sample of these orbits, both from sensor data and from orbital element sets, during the period surrounding the 14 July 2000 solar activity. We present information concerning the effects of this event on the orbits of resident space objects and how well accepted atmospheric models were able to represent it. As part of this analysis, we describe a technique for extracting atmospheric density information from orbital element sets. On daily time scales, the effect of geomagnetic activity appears to be more important than that of prompt radiation. However, the limitations in time and amplitude quantization of the accepted solar indices are evident. A limited comparison is also made with previous solar storm events.  相似文献   

Northern settlement family-style: labor planning and population policy in Noril'sk     

Bond AR 《Soviet geography》1985,26(1):26-47

This paper reviews labor planning and population policies in Noril'sk, a mining and metallurgical settlement in northern Siberia. When the settlement was established in 1935, planners were lacking in ideas about how to recruit workers to staff the mines and smelters and how to retain the labor force once it was in place. From 1935-79, planners followed a forced labor policy dependent upon the labor of prisoners. However, this solution was not adequate for meeting the manpower needs of an economy undergoing rapid technological sophistication. Northern wage increments were introduced after 1945 to recruit skilled workers from other regions. These increments built up over a 4-year period to a maximum of 80% of base pay. A special cost of living bonus was also awarded. Although these inducements facilitated labor recruitment, labor retention remained a major problem. Surveys indicated that workers would prefer improvements in housing and social services to further wage increases. Thus, policy was directed at the housing shortages, poor medical care, and inadequate child care facilities in Noril'sk. Such improvements facilitated labor retention but also contributed to overpopulation. The population doubled between 1956-80, exceeding 180,000 in the latter year. In the early 1980s, selective measures toward population control were implemented to ensure maintenance of living standards (e.g., encouragement of older workers to leave the area upon retirement, more careful screening of recruits). The goal is to stabilize city size at around 250,000. The Noril'sk case illustrates that quality of life investments can alleviate labor retention problems even in the harshest physical environments. Recent policies have advocated productivity-enriching technologies that do not require increments in the labor force.  相似文献   

HIGH SCHOOL GEOGRAPHY PROJECT PROGRESS REPORT     

Nicholas Helburn 《The Professional geographer》1966,18(3):169-169

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On the radiated noise of the autosub autonomous underwater vehicle   总被引：1，自引：2，他引：1  

Griffiths  Gwyn; Enoch  Peter; Millard  Nicholas W. 《ICES Journal of Marine Science》2001,58(6):1195-1200

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The contribution of atmospheric acid deposition to ocean acidification in the subtropical North Atlantic Ocean     

Nicholas R. Bates  Andrew J. Peters   《Marine Chemistry》2007,107(4):547-558

The absorption of anthropogenic CO₂ and atmospheric deposition of acidity can both contribute to the acidification of the global ocean. Rainfall pH measurements and chemical compositions monitored on the island of Bermuda since 1980, and a long-term seawater CO₂ time-series (1983–2005) in the subtropical North Atlantic Ocean near Bermuda were used to evaluate the influence of acidic deposition on the acidification of oligotrophic waters of the North Atlantic Ocean and coastal waters of the coral reef ecosystem of Bermuda. Since the early 1980's, the average annual wet deposition of acidity at Bermuda was 15 ± 14 mmol m^− 2 year^− 1, while surface seawater pH decreased by 0.0017 ± 0.0001 pH units each year. The gradual acidification of subtropical gyre waters was primarily due to uptake of anthropogenic CO₂. We estimate that direct atmospheric acid deposition contributed 2% to the acidification of surface waters in the subtropical North Atlantic Ocean, although this value likely represents an upper limit. Acidifying deposition had negligible influence on seawater CO₂ chemistry of the Bermuda coral reef, with no evident impact on hard coral calcification.  相似文献   

The pre-glacial pleistocene of the Norfolk and Suffolk coasts: R.G. West. Cambridge University Press, London/New York, 1980, 203 pp., 36 plates, 54 figures, 49 tables, £40.00     

Nicholas Stephens 《Marine Geology》1981,40(3-4):271-273

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