The effect of peak shifts on the performance of a Kalman filter multicomponent analysis algorithm hasbeen investigated.A series of Gaussian test systems were employed to characterize the concentrationestimation errors and the morphology of the on-line residuals(the innovations sequence).Both forwardand reverse filters were used in the generation of the innovations sequences.It was found that thedifference between the forward and reverse innovations sequences gave an accurate indication of thedirection and magnitude of the peak shift.A series of overlapped two-component systems were alsoinvestigated.Again,a correlation between the difference innovations and the degree of the responseshift was observed.The behavior of the Katman filter in fitting the shifted fluorescence emissionspectrum of benzo[a]pyrene was also examined.The response for henzo[a]pyrene in cyclohexanesolution was compared to that obtained on the surface of a reversed phase thin layer chromatographyplate.A red shift of 4 nm was detected for the surface spectrum by observing the difference innovationssequence.This approach holds promise for correction of response shifts in multicomponent systems. 相似文献
Fabry-Perot interferometric observations on the green coronal line (λ 5303 å) carried out during the total solar eclipse of 1980 February 16 have yielded relative Doppler shift velocities with an accuracy of ± 7 km s-1. The values show a peak in the 30–50 km s-1 range indicating largescale macroscopic mass motion in the solar maximum corona. 相似文献
Compaction induced by pore‐pressure decrease inside a reservoir can be monitored by measuring traveltime shifts of reflection events on time‐lapse seismic data. Recently we introduced a perturbation‐based formalism to describe traveltime shifts caused by the 3D stress‐induced velocity field around a compacting reservoir. Application of this method to homogeneous background models showed that the offset variation of traveltime shifts is controlled primarily by the anisotropic velocity perturbations and can provide valuable information about the shear and deviatoric stresses. Here, we model and analyse traveltime shifts for compacting reservoirs whose elastic properties are different from those of the surrounding medium. For such models, the excess stress is influenced primarily by the contrast in the rigidity modulus μ across the reservoir boundaries. Synthetic examples demonstrate that a significant (25% or more) contrast in μ enhances the isotropic velocity perturbations outside the reservoir. Nevertheless, the influence of background heterogeneity is mostly confined to the reservoir and its immediate vicinity and the anisotropic velocity changes are still largely responsible for the offset dependence of traveltime shifts. If the reservoir is stiffer than the host rock, the background heterogeneity reduces anisotropic velocity perturbations inside the reservoir but increases them in the overburden. As a result, in this case, the magnitude of the offset variation of traveltime shifts is generally higher for reflections from interfaces above the reservoir. We also study compaction‐induced stress/strain and traveltime shifts for a stiff reservoir embedded in a softer layered model based on velocity profiles from the Valhall Field in the North Sea. Despite producing discontinuities in strain across medium interfaces, horizontal layering does not substantially alter the overall behaviour of traveltime shifts. The most pronounced offset variation of traveltime shifts is observed for overburden events recorded at common midpoints close to the reservoir edges. On the whole, prestack analysis of traveltime shifts should help better constrain compaction‐induced velocity perturbations in the presence of realistic background heterogeneity. 相似文献
Abstract. The behavioural ecology of certain northern Adriatic fishes was observed from January to April at a water temperature of 7–11 oC. The fishes studied here do not migrate to deeper waters. Most of the benthic fishes show a similar distribution over the substrate in winter and in summer; in winter, however, they are very inactive and hide in the substrate. Suprabenthic fishes aggregate in littoral caves where they form dense, inactive, mixed aggregations. Certain hemipelagic and pelagic fishes join to form very dense aggregations at specific sites in the open waters of bays. Littoral predators display high feeding activity at a time when their prey is inactive. I present a hypothesis concerning possible implications of seasonally cyclic environmental temperatures for a sympatric community of non-migrating fishes. 相似文献
In order to examine the responses of primary productivity in the southern coastal sea of Japan to the Pacific Decadal Oscillation
(PDO) in the 20th century, sedimentary records of diatom productivity (diatom valve fluxes) were reconstructed using core
samples from the Bungo Channel (BC) in southwest Japan. The record of the Thalassionema spp. flux—the best index of fall primary productivity in the BC—indicated a multidecadal-scale duration with a low flux (1943–1982)
and those with a high flux (1913–1943 and 1982–2001); apparent shifts were recognized in 1943 and 1982. The shift in 1982
was also recognized in the flux records of other early summer to fall predominant genera in the BC and, previously, in the
biogenic silica records from a broad region of the southeast BC. This indicates that in our records, this shift reflects a
general trend in the primary production in the southeast BC. A comparison among the Thalassionema spp. flux records, meteorological data from an observatory adjacent to the core site, and the PDO index showed that the flux
records were more similar to the PDO index than the other meteorological records, which suggests that the multidecadal-scale
variability of the BC primary productivity may be associated with some marine-derived forcing. The bottom intrusions of nutrient-rich
water that upwelled from the shelf slope into the BC, the axis movement or the transport of the Kuroshio Current off the BC,
and a basin-scale wind stress in the North Pacific might play an important role in this forcing and mediate between the BC
primary productivity and the PDO. 相似文献
Life history, habitat utilisation, and biomass of benthic and pelagic opossum shrimp (Mysis relicta) were studied in the oligotrophic Lake Jonsvatn, central Norway. Sampling in the pelagic zone was done by means of a closing zooplankton net; in the benthic zone by means of a benthic beam trawl.
M. relicta had a mixed one or two year life cycle. In the autumn, the proportion of mature females and males were larger in the pelagic than in the benthic habitat. Copulation took place in late autumn, and the first females with eggs occurred in November. In February, the first juvenile M. relicta were released in the benthic habitat. In May and July, however, juveniles were found in large numbers in all parts of the lake. The length distribution of M. relicta indicates that juveniles partly segregate between benthic and pelagic habitats.
Both juvenile and adult M. relicta performed vertical diel migrations in the pelagic habitat. In the benthic habitat, diel vertical migrations along the bottom were not as pronounced as vertical migrations in the pelagic habitat. In the benthic habitat, major migrations were performed only by adults in the autumn. Our results indicate that the light intensity in the green part of the spectrum gives the proximate cue for regulation of vertical distribution of M. relicta.
The mean total biomass varied between 288 and 1576 kg dry weight, corresponding to 23.2–127.1 mg dry weight m−2 surface area. M. relicta had smallest biomass during late spring/early summer and largest biomass during autumn and early winter. Estimated pelagic biomasses were largest in February, August, October and November, while benthic biomasses were largest in May and July. Estimated biomass of pelagic M. relicta during autumn was approximately 1/10 of the estimated biomass of zooplankton in this lake. 相似文献
We provide a position paper, using a brief literature review and some new modelling results for a subset of succulent plant species, which explores why Namaqualand plant diversity might be particularly vulnerable to anthropogenic climate change despite presumed species resilience under arid conditions, and therefore a globally important test-bed for adaptive conservation strategies. The Pleistocene climate-related evolutionary history of this region in particular may predispose Namaqualand (and Succulent Karoo) plant endemics to projected climate change impacts. Key Succulent Karoo plant lineages originated during cool Pleistocene times, and projected air temperatures under anthropogenic climate change are likely to exceed these significantly. Projected rainfall patterns are less certain, and projections of the future prevalence of coastal fog are lacking, but if either of these water inputs is reduced in concert with rising temperatures, this seems certain to threaten the persistence of, at least, narrow-endemic plant species. Simple modelling approaches show strong reduction in spatial extent of bioclimates typical of Namaqualand within the next five decades and that both generalist species with large geographic ranges, and narrow-range endemics may be susceptible to climate change induced loss of potential range. Persistence of endemics in micro-habitats that are buffered from extreme climate conditions cannot be discounted, though no attempts have been made to address this shortcoming of broader scale bioclimatic modelling. The few experimental data available on elevated temperature and drought tolerance suggest susceptibility of leaf succulent species, but high drought tolerance of non-succulent shrubs. Both species-level monitoring and further experimental work is essential to test and refine projections of climate change impacts on species persistence, and the implications for conservation. 相似文献