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排序方式: 共有124条查询结果,搜索用时 46 毫秒
71.
R. G. Dzhamalov N. L. Frolova A. V. Stanovova G. N. Krichevets Chung-Ho Wang Kuo-Chin Hsu Feng-Sheng Chiu Cheng-Haw Lee Ming-Chee Wu 《Water Resources》2012,39(5):610-621
The dynamics of climate and runoff characteristics are studied in the territories of Kamchatka Peninsula and Taiwan Island, which are situated in the influence zone of monsoon circulation. Long-term variations in the temperature, precipitation, and runoff are examined in Kamchatka and Taiwan for the weather and gauging stations with the longest observation series to analyze new climate conditions of water resources generation. 相似文献
72.
73.
S.G. Cheung C.Y.S. Chan B.H.K. Po A.L. Li J.Y.S. Leung J.W. Qiu P.O. Ang V. Thiyagarajan P.K.S. Shin J.M.Y. Chiu 《Marine pollution bulletin》2014
Biofilms on submerged surfaces are important in determining larval settlement of most marine benthic invertebrates. We investigated if exposure of biofilms to hypoxia would alter the larval settlement pattern and result in a shift in benthic invertebrate community structure in the field. Biofilms were first exposed to hypoxia or normoxia in laboratory microcosms for 7 days, and then deployed in the field for another 7 days to allow for larval settlement and recruitment to occur. Using terminal-restriction fragment length polymorphism of the 16S rRNA gene, this study showed that hypoxia altered the biofilm bacterial community composition, and the difference between the hypoxic and normoxic treatments increased with the time of exposure period. This study also demonstrated significantly different benthic invertebrate community structures as a result of biofilm exposure to hypoxia and that the hypoxic and normoxic treatments were dominated by Hydroides sp. and Folliculina sp., respectively. 相似文献
74.
Scott M. Croom Gordon T. Richards Tom Shanks Brian J. Boyle Robert G. Sharp Joss Bland-Hawthorn Terry Bridges Robert J. Brunner Russell Cannon Daniel Carson Kuenley Chiu Matthew Colless Warrick Couch Roberto De Propris Michael J. Drinkwater Alastair Edge Stephen Fine Jon Loveday Lance Miller Adam D. Myers Robert C. Nichol Phil Outram Kevin Pimbblet Isaac Roseboom Nicholas Ross Donald P. Schneider Allyn Smith Chris Stoughton Michael A. Strauss David Wake 《Monthly notices of the Royal Astronomical Society》2009,392(1):19-44
We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG (luminous red galaxy) and QSO (2SLAQ) survey. This is a deep, 18 < g < 21.85 (extinction corrected), sample aimed at probing in detail the faint end of the broad line active galactic nuclei luminosity distribution at z ≲ 2.6 . The candidate QSOs were selected from SDSS photometry and observed spectroscopically with the 2dF spectrograph on the Anglo-Australian Telescope. This sample covers an area of 191.9 deg2 and contains new spectra of 16 326 objects, of which 8764 are QSOs and 7623 are newly discovered [the remainder were previously identified by the 2dF QSO Redshift Survey (2QZ) and SDSS]. The full QSO sample (including objects previously observed in the SDSS and 2QZ surveys) contains 12 702 QSOs. The new 2SLAQ spectroscopic data set also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow emission-line galaxies with a median redshift of z = 0.22 .
We present detailed completeness estimates for the survey, based on modelling of QSO colours, including host-galaxy contributions. This calculation shows that at g ≃ 21.85 QSO colours are significantly affected by the presence of a host galaxy up to redshift z ∼ 1 in the SDSS ugriz bands. In particular, we see a significant reddening of the objects in g − i towards the fainter g -band magnitudes. This reddening is consistent with the QSO host galaxies being dominated by a stellar population of age at least 2–3 Gyr.
The full catalogue, including completeness estimates, is available on-line at http://www.2slaq.info/ . 相似文献
We present detailed completeness estimates for the survey, based on modelling of QSO colours, including host-galaxy contributions. This calculation shows that at g ≃ 21.85 QSO colours are significantly affected by the presence of a host galaxy up to redshift z ∼ 1 in the SDSS ugriz bands. In particular, we see a significant reddening of the objects in g − i towards the fainter g -band magnitudes. This reddening is consistent with the QSO host galaxies being dominated by a stellar population of age at least 2–3 Gyr.
The full catalogue, including completeness estimates, is available on-line at http://www.2slaq.info/ . 相似文献
75.
The mechanical behaviour of three cement-treated dredged materials (DM) was studied in the laboratory by isotropic compression and undrained triaxial tests. The intrinsic properties of the untreated and reconstituted soil were used as a reference framework to interpret the effect of cementation on the mechanical behaviour of the cement-treated DM. The isotropic compression line of the reconstituted soil is termed the intrinsic normal compression line (INCL). It is found that the isotropic compression lines of the cement-treated DM lie above the INCL, i.e. the void ratio of the cement-treated soil is higher than that of the reconstituted soil for a given confining pressure. The yield stress measured from the isotropic compression tests increases with increasing cement content and curing time. The pre-yield and post-yield shear responses of the cement-treated DM are different. Pre-yield soil specimens show a tendency to dilate, but post-yield soil specimens show a tendency to contract. Failure envelopes of the cement treated DM lie above that of the reconstituted DM. Linear Mohr–Coulomb failure envelopes were observed for the range of applied stress used in the study. The cohesion intercept increases with increasing cement content and curing time. The strength enhancement of the cement-treated DM is the result of the structures developed during cementation process. Based on a recently proposed soil water transfer model, the change in normalised bound water content, (Δmbw)N, is used to evaluate the combined effects of cement content and curing period on the mechanical behaviour of the cement-treated DM. It is found that there exists a threshold value of (Δmbw)N, beyond which the yield stress and cohesion intercept increases nonlinearly with increasing (Δmbw)N. The threshold value is equal to 0.37 for the three DM used in the study. 相似文献
76.
Total Hg (∑Hg), organic-Hg (O-Hg) and Se bioaccumulations in small cetaceans distributed in Taiwanese waters of the Taiwan Strait and the southwestern Pacific have been investigated for the first time. The results could represent the baseline metal concentrations of marine mammals in the southwestern Pacific, where volcanic activities are possibly the major source of mercury to the environments. Muscle samples of four species of small cetaceans were collected from animals accidentally caught by tuna-longline fisheries from 1994 through 1995. In total, 53 pantropical spotted dolphins, Stenella attenuata, nine spinner dolphins, S. longirostris, five bottlenose dolphins, Turiops truncatus and four Risso's dolphins, Grampus giseus were analyzed. In addition, two stranded pantropical spotted dolphins were investigated. Cold vapour AAS and ICP-MS were used in the analysis of Hg and Se, respectively. Significant species difference was found in the four species of small cetaceans. Among them, the pantropical spotted dolphin showed the highest mean concentration (mg/kg wet wt.) of both ∑Hg (3.64±2.19) and O-Hg (2.79±1.23), whereas the Risso's dolphin had the highest mean concentrations of Se (1.77±1.29). There was no significant sex difference with respect to metal bioaccumulation in the samples of S. attenuata. Significant correlations between body length (BL) and ∑Hg, as well as O-Hg concentrations were observed in pantropical spotted (Sa) and spinner dolphins (Sl). The linear relationships were Sa: ∑Hg=−8.290+0.066BL, r=0.421; Sl: ∑Hg=−2.735+0.025BL, r=0.875; Sa: O-Hg=−3.723+0.036BL, r=0.408; and Sl: O-Hg=−3.017+0.025BL, r=0.870. However, a demethylation phenomenon that decreasing the percentage of O-Hg coupled with increasing levels of Se was observed when the ∑Hg concentrations in the muscle tissues of dolphins reached 4 mg/kg wet wt. 相似文献
77.
—?Four days after the December 13, 1990 Hualien, Taiwan earthquake (M L = 6.9), a temporary array of fifteen triaxial digital accelerographs was deployed in the epicenter area to monitor aftershocks. Approximately 600 earthquakes triggered this array during the three-month deployment period. The Yan-Liau station (S63) alone recorded 162 events. Most of the accelerograms at S63 exhibit resonance. We have estimated site responses at the Yan-Liau station using both the single-station spectral ratio (or H/V ratio) method and the traditional spectral ratio method that compares ratios at a soil site with those at a reference hard rock site. Based on site response analyses of S waves and coda waves of ground motion recordings, both types of waves show that the H/V ratio provide a good estimate at the resonant frequency although the site amplification factor is overestimated. In addition, the study of microtremor is also a good alternate for estimating the site predominant frequency. While the ground acceleration (or PGA) gradually increases, the resonant frequency shifts to lower frequencies. 相似文献
78.
The free-field accelerograms along Feitsui Canyon are analysed and modelled by a numerical scheme to study the effect of canyon topography. Six strong-motion accelerometers (SC1–SC6) were deployed along the Feitsui Canyon in 1991. The observations suggest that the amplitude of ground motion at the trough of the canyon is smaller than that on its slopes. The integral equation method is applied to a two-dimensional model of Feitsui Canyon to study the effects of the canyon topography. We choose the ground motion of SC3 station at the trough of the canyon as the input motion to the model, which is then used to predict the ground motion at the other five stations. The simulated and observed seismograms agree well in displacement and velocity, although the simulated acceleration at high frequency is underestimated. The simple model can reproduce the observed accelerations at all frequencies below 4 Hz. 相似文献
79.
D. K. Y. Chiu A. K. C. Wong 《Stochastic Environmental Research and Risk Assessment (SERRA)》1987,1(1):67-80
This paper presents a pattern analysis technique that has been successfully applied to a set of hydrometric network data collected in British Columbia, Canada. This technique can extract information from a set of observed heterogeneous multivariate data. The data are represented as n-tuples of mixed discrete and continuous values. The technique is capable of screening out statistically irrelevant information. It is also able to detect inherent subgroups in the data through adopting an event-covering approach. The subgroup characteristics represent important empirical understanding even though there may be considerable probabilistic variation within each individual subgroup. 相似文献
80.
A GIS-based decision support system, which incorporates local topographic and rainfall effects on debris flow vulnerability
is developed. Rainfall at a scale compatible with the digital elevation model resolution is obtained using a neural network
with a wind-induced topographic effect and rainfall derived from satellite rain estimates and an adaptive inverse distance
weight method (WTNN). The technique is tested using data collected during the passage of typhoon Tori-Ji on July 2001 over
central Taiwan. Numerous debris flows triggered by the typhoon were used as control for the study. Our results show that the
WTNN technique outperforms other interpolation techniques including adaptive inversed distance weight (AIDW), simple kriging
(SK), co-kriging, and multiple linear regression using gauge, and topographic parameters. Multiple remotely-sensed, fuzzy-based
debris-flow susceptibility parameters are used to describe the characteristics of watersheds. Non-linear, multi-variant regressions
using the WTNN derived rainfall and topography factors are derived using self-organizing maps (SOM) for the debris flow vulnerability
assessment. An index of vulnerability representing the degrees of hazard is implemented in a GIS-based decision support system
by which a decision maker can assess debris flow vulnerability. 相似文献