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901.
Multiobjective optimization deals with mathematical optimization problems where two or more objective functions (cost functions) are to be optimized (maximized or minimized) simultaneously. In most cases of interest, the objective functions are in conflict, i.e., there does not exist a decision (design) vector (vector of optimization variables) at which every objective function takes on its optimal value. The solution of a multiobjective problem is commonly defined as a Pareto front, and any decision vector which maps to a point on the Pareto front is said to be Pareto optimal. We present an original derivation of an analytical expression for the steepest descent direction for multiobjective optimization for the case of two objectives. This leads to an algorithm which can be applied to obtain Pareto optimal points or, equivalently, points on the Pareto front when the problem is the minimization of two conflicting objectives. The method is in effect a generalization of the steepest descent algorithm for minimizing a single objective function. The steepest-descent multiobjective optimization algorithm is applied to obtain optimal well controls for two example problems where the two conflicting objectives are the maximization of the life-cycle (long-term) net-present-value (NPV) and the maximization of the short-term NPV. The results strongly suggest the multiobjective steepest-descent (MOSD) algorithm is more efficient than competing multiobjective optimization algorithms. 相似文献
902.
Because the land requisition and demolishing became difficult more and more, the mining scheme of Luohe iron mine was changed from caving method to filling method. In order to ensure the safety of the residence and the underground tunnel cavern within the mobile belt of the underground mining, the Luohe iron mine did the blasting test on the vertical crater retreat mining method and blasting vibration monitoring. The blasting experiments use common emulsified oil explosives and non-electric initiation system. The way of caved ore adopts the cutting groove and bench side. The NUBOX-6016 intelligent vibration monitor was chosen in the blasting vibration monitoring. Twice experiments on the blasting vibration monitoring were done on the surface or in the underground refuge cavern. The first test select the three monitoring points on the ground and the second select two monitoring points on the ground and a monitoring point in the underground refuge cavern. The blasting vibration monitoring data were conducted by the regression analysis in the Sodev’s empirical formula. The vibration attenuation formula about the underground blasting vibration transmitting in three directions is derived. The blasting test on the vertical crater retreat mining method and the blasting vibration were analyzed. It is estimated if the vibration damage possibly the surface buildings and related facilities of mine. 相似文献
903.
Dong Liu Dan Zhao Qiang Fu Qiuchen Wu Yongjia Zhang Tianxiao Li Khan M Imran Faiz M Abrar 《Arabian Journal of Geosciences》2016,9(20):746
In this paper, the self-adaptive artificial fish swarm algorithm (SAAFSA) is used to optimize the coarse graining of segment numbers, which are used in the Lempel-Ziv complexity algorithm. This approach improves the Lempel-Ziv complexity (LZC) algorithm of equal probability coarse graining. As a case study, the complexities of monthly series of groundwater depth were analyzed at seven farms in the Hongxinglong Administration. GIS technology was used to create spatial distributions of monthly groundwater depths. A projection pursuit model based on the SAAFSA was established and used for complexity attribution analysis at selected farms with different degrees of complexity. The three selected farms, Hongqiling, 852, and Youyi, each represent a certain degree of complexity. Further analysis shows that precipitation, evaporation, temperature, and human activities are the primary factors that cause complexity variations in local groundwater depth. The results reveal the evolution of the complexity characteristics of local groundwater depth and provide scientific evidence for the need to effectively allocate regional water resources. Additionally, the proposed method can be applied in complexity analyses of other hydrologic features, as well as in research regarding nonlinear time series in economic, engineering, medical, and signal analyses. 相似文献
904.
Near-surface layer variations can degrade the desired response of seismic arrays which are typically used to attenuate horizontally traveling coherent noise and enhance vertically traveling signal. We investigate the effect of variations in the near-surface layer thickness on the performance of arrays by studying their impulse and wavelet responses. The models considered include the topographic variations and a channel in the base of weathering layer. The topographic variations include a dipping surface layer as well as a surface layer that follows a sine wave. The geological channel is assumed to be present under the entire receiver array as well as partially under a few receivers. We use Ricker wavelet and model plane wavefronts with incidence angles (90, 70, 45, 20, and 5 °) on a 12-element equally weighted array for the weathering layer models. We found that the array responses are more degraded for near-vertically traveling waves in all cases. The array responses are also found to be more degraded when channel variations are present underneath a few receivers as compared to the entire array length. We recommend designing a spatial filter or using single-sensor records after correcting for intra-array statics to preserve the reflection amplitudes in the presence of weathering layer variations. 相似文献
905.
Koushik Sen Ruchika Sharma B. R. Arora Vikram Gupta 《Journal of the Geological Society of India》2010,76(4):322-330
Anisotropy of Magnetic Susceptibility (AMS) and seismic wave velocity studies of some paramagnetic Himalayan granitoids show good correlation between magnetic fabric anisotropy and P wave velocity (Vp). Vp shows strong positive correlation with magnetic lineation (L) and degree of magnetic anisotropy (P′) having correlation coefficient (r) values of 0.93 and 0.89 respectively. Both Vp and Vs show positive correlation with the SiO2 content of Proterozoic and Paleozoic granitoids. Velocity of S wave (Vs) shows negative correlation with mean magnetic susceptibility (Km) having ‘r’ value of 0.86. The correlation between Vs-Km, Vp-P′, Vp-L also shows >95% probability in Spearman’s rank correlation. Based on the results from the present sample size it is suggested that, in paramagnetic granites, Vp is proportional to intensity of deformation and preferred orientation of minerals as well as the mineralogy. On the other hand, Vs is more dependent on the mineralogy alone. 相似文献
906.
Precambrian crystalline basement in southern Mongolia as revealed by SHRIMP zircon dating 总被引:5,自引:0,他引:5
Antoine Demoux Alfred Kröner Dunyi Liu Gombosuren Badarch 《International Journal of Earth Sciences》2009,98(6):1365-1380
Single zircon ages determined by ion microprobe (SHRIMP II) for granitoid gneisses from the southern slope of the Baga Bogd
massif (Gobi-Altai, southern Mongolia) reveal several episodes of zircon growth, ranging from late Palaeoproterozoic to late
Cambrian. The oldest events are documented by a zircon crystallization age for a gneiss protolith at 1519 ± 11 Ma and by a
xenocrystic zircon from a dark grey augen-gneiss yielding an age of c. 1701 Ma. Discrete igneous events are recorded in granite-gneisses
with protolith emplacement ages of 983 ± 6, 956 ± 3 and 954 ± 8 Ma. These ages provide the first record of early Neoproterozoic
magmatic activity in this region. A much younger and discrete magmatic event is recorded by several dioritic to granitic orthogneisses
which are tectonically interlayered with the older gneisses and have protolith emplacement ages between 502 and 498 Ma. These
late Cambrian granitoids of calc-alkaline affinity are likely to have been emplaced along an active continental margin and
suggest that the Baga Bogd Precambrian crustal fragment was either docked against the southward (present-day coordinates)
growing margin of the CAOB or was a large enough crustal entity to develop an arc along its margin. We speculate that the
Precambrian gneisses of this massif may be part of a crustal fragment rifted off the Tarim Craton. 相似文献
907.
Geodynamic evolution of Central Asia in the Paleozoic and Mesozoic 总被引:18,自引:0,他引:18
Wenjiao Xiao Alfred Kröner Brian Windley 《International Journal of Earth Sciences》2009,98(6):1185-1188
908.
Martin Reich Carlos Palacios Macarena Alvear Eion M. Cameron Matthew I. Leybourne Artur Deditius 《Mineralium Deposita》2009,44(6):719-722
Recent studies have suggested the involvement of highly saline deep formation waters that modified preexisting Cu assemblages
to form atacamite during supergene oxidation of Cu deposits in the Atacama region. In this report, we document the occurrence
of (Ag–I) inclusions hosted by supergene chalcocite from Mantos de la Luna, an argentiferous Upper Jurassic stratabound Cu
deposit in the Coastal Range of northern Chile. The presence of this unusual mineral assemblage indicates that iodargyrite
precipitated from reducing iodine-rich waters, suggesting that the fluids involved in supergene enrichment of Cu deposits
in the Coastal Range were more complex than previously thought. This suggests the prevalence of hyperarid conditions during
the latest stages of supergene enrichment of the Mantos de la Luna Cu deposit in the Atacama region, supporting the notion
that supergene enrichment processes in hyperarid areas are dynamic in nature and do not exclusively require the presence of
meteoric water. 相似文献
909.
Slavica Matijević Natalia Bojanić Grozdan Kušpilić Živana Ninčević Gladan 《Environmental Earth Sciences》2009,59(4):853-866
Phosphorus (P) species concentrations in 0–2 cm surface sediment layer were investigated monthly from November 2001 to December
2002 at the bay, channel and open sea stations in the middle Adriatic. Modified SEDEX method was used for inorganic phosphorus
species determination [P in biogenic (P-FD), authigenic (P-AUT), detrital apatite (P-DET) and P adsorbed on to iron oxides
and hydroxides (P–Fe)], and organic phosphorus (P-ORG). P-FD, P-AUT and P-DET concentration ranges (1.5–5.4, 0–2.7 and 0.4–3.4 μmol g−1, respectively) were similar at all stations, and showed no obvious common trend of seasonal changes. P–Fe ranged from 1.9
to 11.9 μmol g−1 with the highest values at bay station and higher seasonal oscillations than other inorganic P forms. P-ORG ranged from 0.3
to 18.7 μmol g−1 with higher concentrations at stations of fine-sized sediments and showed increased concentrations in warm part of the year
at all stations. Correlation between concentrations of P–Fe in the surface sediment layer and orthophosphate sediment-water
interface concentration gradients at bay and channel stations indicated to P–Fe importance in the orthophosphate benthic flux.
For the bay station, linkage between sediment P-ORG and chlorophyll a concentrations, primary production and microzooplankton abundance was established, indicating a 1 month delay of sediment
response to production fluctuations in the water column. 相似文献
910.
Rock displacement and thermal expansion study at historic heritage sites in Slovakia 总被引:1,自引:0,他引:1
Jan Vlcko Vladimir Greif Vladimir Grof Michal Jezny Lubomir Petro Martin Brcek 《Environmental Geology》2009,58(8):1727-1740
The paper discusses the results of the research devoted to the preservation of cultural heritage carried out within last two
decades in Slovakia. The aim of the study depended on monitoring of selected castle rocks showing instability problems due
to extremely slow displacements of creep character. Apart from traditional methods of investigation at one test site (Spis
Castle), authors implemented in their work the study of thermal expansion of the rocks as a result of seasonal periodic temperature
changes having potential influence on displacements and numerical modeling in order to understand better the landslide failure
mechanism. The results obtained from all study sites confirmed that even slow movements have to be implemented into preservation
and stabilization works in order to safeguard the sites of great historic value. 相似文献