排序方式： 共有26条查询结果，搜索用时 15 毫秒
1.
Concentration–discharge relationships in the coal mined region of the New River basin and Indian Fork sub‐basin,Tennessee, USA 
下载免费PDF全文
下载免费PDF全文 For many basins, identifying changes to water quality over time and understanding current hydrologic processes are hindered by fragmented and discontinuous water‐quality and hydrology data. In the coal mined region of the New River basin and Indian Fork sub‐basin, muted and pronounced changes, respectively, to concentration–discharge (C–Q) relationships were identified using linear regression on log‐transformed historical (1970s–1980s) and recent (2000s) water‐quality and streamflow data. Changes to C–Q relationships were related to coal mining histories and shifts in land use. Hysteresis plots of individual storms from 2007 (New River) and the fall of 2009 (Indian Fork) were used to understand current hydrologic processes in the basins. In the New River, storm magnitude was found to be closely related to the reversal of loop rotation in hysteresis plots; a peak‐flow threshold of 25 cubic meters per second (m3/s) segregates hysteresis patterns into clockwise and counterclockwise rotational groups. Small storms with peak flow less than 25 m3/s often resulted in dilution of constituent concentrations in headwater tributaries like Indian Fork and concentration of constituents downstream in the mainstem of the New River. Conceptual two or three component mixing models for the basins were used to infer the influence of water derived from spoil material on water quality. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
Following success in remotely operated vehicle (ROV) designs such as MMIM, IZE, SOLO, ORVIL, CIRRUS, PIC, and OBSERVER, Slingsby Engineering Limited (SEL) has now developed its technology to build and prove a new ROV, TROJAN. TROJAN is a dedicated subsea support vehicle, which results from extensive market research being applied to a base of 15 years in the underwater technology market. SEL has been at the forefront of the evolution of this market from early manned submersible days, followed by atmospheric diving systems to ROV's. The TROJAN ROV is conceived as a subsea workhorse offering a new dimension to subsea support operations. TROJAN benefits by incorporation of proven technology developed by SEL in recent years on SOLO, PIC, and CIRRUS projects. Using standard components, TROJAN's high reliability and efficient performance offer a versatile and cost-effective work system. 相似文献
3.
Andrew R. Liddle Pedro T. P. Viana A. Kathy Romer Robert G. Mann 《Monthly notices of the Royal Astronomical Society》2001,325(2):875-880
The redshift evolution of the galaxy cluster temperature function is a powerful probe of cosmology. However, its determination requires the measurement of redshifts for all clusters in a catalogue, which is likely to prove challenging for large catalogues expected from XMM-Newton , which may contain of the order of 2000 clusters with measurable temperatures, distributed around the sky. In this paper we study the apparent cluster temperature, which can be obtained without cluster redshifts. We show that the apparent temperature function itself is of limited use in constraining cosmology, and so concentrate our focus on studying how apparent temperatures can be combined with other X-ray information to constrain the cluster redshift. We also briefly study the circumstances under which the non-thermal spectral features can provide redshift information. 相似文献
4.
5.
6.
Andrew R. Liddle 《Astrophysics and Space Science》1998,261(1-4):281-290
I give a status report and outlook concerning the use of the cosmic microwave background anisotropies to constrain the inflationary
cosmology, and stress its crucial role as an underlying paradigm for the estimation of cosmological parameters.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Scott T. Kay Leila C. Powell rew R. Liddle Peter A. Thomas 《Monthly notices of the Royal Astronomical Society》2008,386(4):2110-2114
The relativistic Sunyaev–Zel'dovich (SZ) effect offers a method, independent of X-ray, for measuring the temperature of the intracluster medium (ICM) in the hottest systems. Here, using N -body/hydrodynamic simulations of three galaxy clusters, we compare the two quantities for a non-radiative ICM, and for one that is subject both to radiative cooling and to strong energy feedback from galaxies. Our study has yielded two interesting results. First, in all cases, the SZ temperature is hotter than the X-ray temperature and is within 10 per cent of the virial temperature of the cluster. Secondly, the mean SZ temperature is less affected by cooling and feedback than the X-ray temperature. Both these results can be explained by the SZ temperature being less sensitive to the distribution of cool gas associated with cluster substructure. A comparison of the SZ and X-ray temperatures (measured for a sample of hot clusters) would therefore yield interesting constraints on the thermodynamic structure of the intracluster gas. 相似文献
8.
Edmund J. Copeland Ian J. Grivell & Andrew R. Liddle 《Monthly notices of the Royal Astronomical Society》1998,298(4):1233-1238
Accurate estimation of cosmological parameters from microwave background anisotropies requires high-accuracy understanding of the cosmological model. Normally, a power-law spectrum of density perturbations is assumed, in which case the spectral index n can be measured to around ± 0.004 using microwave anisotropy satellites such as MAP Planck . However, inflationary models generically predict that the spectral index n of the density perturbation spectrum will be scale-dependent. We carry out a detailed investigation of the measurability of this scale dependence by Planck , including the influence of polarization on the parameter estimation. We also estimate the increase in the uncertainty in all other parameters if the scale dependence has to be included. This increase applies even if the scale dependence is too small to be measured, unless it is assumed absent. We study the implications for inflation models, beginning with a brief examination of the generic slow-roll inflation situation, and then move to a detailed examination of a recently devised hybrid inflation model for which the scale dependence of n may be observable. 相似文献
9.
Julien Lesgourgues rew R. Liddle 《Monthly notices of the Royal Astronomical Society》2001,327(4):1307-1312
We use a wide range of observations to constrain cosmological models possessing a significant asymmetry in the lepton sector, which offer perhaps the best chance of reconciling a critical-density Universe with current observations. The simplest case, with massless neutrinos, fails to fit many experimental data and does not lead to an acceptable model. If the neutrinos have mass of order 1 eV (which is favoured by some neutrino observations), then models can be implemented which prove a good fit to the microwave anisotropies and large-scale structure data. However, taking into account the latest microwave anisotropy results, especially those from BOOMERANG, we show that the model can no longer accommodate the observed baryon fraction in clusters. Together with the observed acceleration of the present Universe, this puts considerable pressure on such critical-density models. 相似文献
10.
Antonio C. da Silva Domingos Barbosa rew R. Liddle Peter A. Thomas 《Monthly notices of the Royal Astronomical Society》2001,326(1):155-163
We use hydrodynamical N -body simulations to study the kinetic Sunyaev–Zel'dovich effect. We construct sets of maps, one square degree in size, in three different cosmological models. We confirm earlier calculations that on the scales studied the kinetic effect is much smaller than the thermal (except close to the thermal null point), with an rms dispersion smaller by about a factor of 5 in the Rayleigh–Jeans region. We study the redshift dependence of the rms distortion and the pixel distribution at the present epoch. We compute the angular power spectra of the maps, including their redshift dependence, and compare them with the thermal Sunyaev–Zel'dovich effect and with the expected cosmic microwave background anisotropy spectrum as well as with determinations by other authors. We correlate the kinetic effect with the thermal effect both pixel-by-pixel and for identified thermal sources in the maps to assess the extent to which the kinetic effect is enhanced in locations of strong thermal signal. 相似文献