Soil acidity adaptive control problem     

Victor P. Yakushev  Vladimir V. Karelin  Vladimir M. Bure  Elena M. Parilina 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(6):1671-1677

Problem of soil acidity regularization is modeled as stochastic adaptive control problem with a linear difference equation of the dynamics of a field pH level. Stochastic component in the equation represents an individual time variability of soil acidity of an elementary section. We use Bayesian approach to determine a posteriori probability density function of the unknown parameters of the stochastic transition process. The Kullback–Leibler information divergence is used as a measure of difference between true distribution and its estimation. Algorithm for the construction of an adaptive stabilizing control in such a linear control system is proposed in the paper. Numerical realization of the algorithm is represented for a problem of a field soil acidity control.  相似文献   

Petrological and experimental evidence for differentiation of water-rich magmas beneath St. Kitts,Lesser Antilles     

Elena?MelekhovaEmail author  Jon?Blundy  Rita?Martin  Richard?Arculus  Michel?Pichavant 《Contributions to Mineralogy and Petrology》2017,172(11-12):98

St. Kitts lies in the northern Lesser Antilles, a subduction-related intraoceanic volcanic arc known for its magmatic diversity and unusually abundant cognate xenoliths. We combine the geochemistry of xenoliths, melt inclusions and lavas with high pressure–temperature experiments to explore magma differentiation processes beneath St. Kitts. Lavas range from basalt to rhyolite, with predominant andesites and basaltic andesites. Xenoliths, dominated by calcic plagioclase and amphibole, typically in reaction relationship with pyroxenes and olivine, can be divided into plutonic and cumulate varieties based on mineral textures and compositions. Cumulate varieties, formed primarily by the accumulation of liquidus phases, comprise ensembles that represent instantaneous solid compositions from one or more magma batches; plutonic varieties have mineralogy and textures consistent with protracted solidification of magmatic mush. Mineral chemistry in lavas and xenoliths is subtly different. For example, plagioclase with unusually high anorthite content (An_≤100) occurs in some plutonic xenoliths, whereas the most calcic plagioclase in cumulate xenoliths and lavas are An₉₇ and An₉₅, respectively. Fluid-saturated, equilibrium crystallisation experiments were performed on a St. Kitts basaltic andesite, with three different fluid compositions (XH₂O = 1.0, 0.66 and 0.33) at 2.4 kbar, 950–1025 °C, and fO₂ = NNO ? 0.6 to NNO + 1.2 log units. Experiments reproduce lava liquid lines of descent and many xenolith assemblages, but fail to match xenolith and lava phenocryst mineral compositions, notably the very An-rich plagioclase. The strong positive correlation between experimentally determined plagioclase-melt Kd_Ca–Na and dissolved H₂O in the melt, together with the occurrence of Al-rich mafic lavas, suggests that parental magmas were water-rich (> 9 wt% H₂O) basaltic andesites that crystallised over a wide pressure range (1.5–6 kbar). Comparison of experimental and natural (lava, xenolith) mafic mineral composition reveals that whereas olivine in lavas is predominantly primocrysts precipitated at low-pressure, pyroxenes and spinel are predominantly xenocrysts formed by disaggregation of plutonic mushes. Overall, St. Kitts xenoliths and lavas testify to mid-crustal differentiation of low-MgO basalt and basaltic andesite magmas within a trans-crustal, magmatic mush system. Lower crustal ultramafic cumulates that relate parental low-MgO basalts to primary, mantle -derived melts are absent on St. Kitts.  相似文献   

Batisite,Na2BaTi2(Si4O12)O2, from Inagli massif,Aldan, Russia: crystal-structure refinement and high-temperature X-ray diffraction study     

Zolotarev  Andrey A.  Zhitova  Elena S.  Gabdrakhmanova  Faina A.  Krzhizhanovskaya  Maria G.  Zolotarev  Anatoly A.  Krivovichev  Sergey V. 《Mineralogy and Petrology》2017,111(6):843-851

Mineralogy and Petrology - The crystal structure of batisite, Na2BaTi2 (Si4O12)O2, from the Inagli massif (Aldan, Yakutia, Russia) was refined to R 1 = 0.032 for 1449 unique...  相似文献   

The results of geochronological and isotope–geochemical study of zircons from tuff of the Sylvitsa Group (western slope of the Middle Urals): The origin of ash layers in Vendian rocks of the East European Platform     

Kuznetsov  N. B.  Belousova  E. A.  Krupenin  M. T.  Romanyuk  T. V.  Maslov  A. V. 《Doklady Earth Sciences》2017,473(1):359-362

Doklady Earth Sciences - New LA-ICP-MS data on the U–Pb isotope age, Hf isotope characteristics, and concentrations of trace elements in zircons from volcanic tuff of the Upper Vendian...  相似文献   

Dynamic of Sea Water Interface using Hydrochemical Facies Evolution Diagram     

Elena Giménez-Forcada 《Ground water》2010,48(2):212-216

This paper analyzes the results of a theoretical simulation of sea water intrusion and its dynamics. The assignment of hydrochemical facies identifies whether the aquifer is in the phase of sea water intrusion or freshening, indicating the status of the aquifer in terms of the advance or regression of the saline front. A new multi-rectangular diagram is proposed that aids interpretation of these important processes through the representation and evolution of hydrochemical facies (hydrochemical facies evolution diagram, HFE-D). As an example, the HEF-D is applied to an alluvial aquifer in the Vinaroz-Peñíscola Plain (Spain), where Ca-Cl facies characterize the sea water intrusion phase, while Na-MixHCO₃/MixSO₄ facies characterize a freshening stage.  相似文献   

Numerical reconstruction of trajectory of small-size surface drifter in the Mediterranean sea     

Elena Y. Shchekinova  Yogesh Kumkar  Giovanni Coppini 《Ocean Dynamics》2016,66(2):153-161

In this study, we addressed the effects of wind-induced drift on Lagrangian trajectories of surface sea objects using high-resolution ocean forecast and atmospheric data. Application of stochastic Leeway model for prediction of trajectories drift was considered for the numerical reconstruction of the Elba accident that occurred during the period 21.06.2009–22.06.2009: a person on an inflatable raft was lost in the vicinity of the Elba Island coast; from the initial position, the person on a raft drifted southwards in the open sea and later he was found on a partially deflated raft during rescue operation. For geophysical forcing, we used high-resolution currents from the Mediterranean Forecasting System and atmospheric wind from the European Centre for Medium-Range Weather Forecasts. To investigate the effect of wind on trajectory behavior, numerical simulations were performed using different categories of drifter-like particles similar to a person on an inflatable raft. An algorithm of spatial clustering was used to differentiate the most probable search areas with a high density of particles. Our results showed that the simulation scenarios using particles with characteristics of draft-limited sea drifters provided better prediction of an observed trajectory in terms of the probability density of particles.  相似文献   

Land Cover Change Characteristics of North-South Transect in Northeast Asia from 2001 to 2012     

WANG Juanle  SU Ping  Elena A. Grigorieva 《资源与生态学报(英文版)》2016,7(1):36-43

Northeast Asia is an area with relative concentrations of resources, a complex ecological environment pattern, and a marked human-land contrast relationship. This area has significance for analyzing land cover patterns and variations for regional sustainable development among the trans-boundary areas of China, Russia, and Mongolia. In this paper, the transect analysis research tool and transfer matrix method are used to capture the regional land cover change characteristics by using Moderate Resolution Imaging Spectroradiometer(MODIS) datasets recorded from 2001 to 2012.The spatial distribution results show that forests have increased dramatically, cropland increased marginally, and grassland and shrubs decreased totally. The inter-annual variation, results show a steady and slowly increasing trend for grassland and shrubs, dramatic fluctuation features with an increasing trend for forest land, and zigzag wave changing characteristic for cropland. The total land use dynamic degree (TLUDD)was steady, with an overall slightly increasing trend.  相似文献   

Late Pleistocene and Holocene vegetation and climate records from Lake Kotokel, central Baikal region     

Koji Shichi  Hikaru Takahara  Sergey K. Krivonogov  Elena V. Bezrukova  Kenji Kashiwaya  Akihide Takehara  Toshio Nakamura 《Quaternary International》2009,205(1-2):98

Climatically driven Late Pleistocene and Holocene vegetation changes were reconstructed based on pollen records from the sediments of Lake Kotokel and Cheremushka Bog, located on the eastern shore of Lake Baikal. The described paleoenvironmental record has higher resolution than records collected from Lake Baikal and unites individual events identified in prior studies of bottom and onshore cores. Remarkable shifts in landscapes and expansions of index plants are as follows. Forest tundra and/or forest steppe landscape with birch, spruce, Artemisia, and Poaceae prevailed at ca. 50–25 ¹⁴C kyr BP. Tundra and/or steppe vegetation dominated by Artemisia and Poaceae was typical for the Last Glacial Maximum. The expansion of shrub birch and willow occurred at ca. 15.5 ¹⁴C kyr BP. Two peaks of spruce expansion at ca. 47.5–42.4 ¹⁴C kyr BP (Karginian time) and at ca. 14.5–13 ka (Bølling-Allerød warm intervals) suggest that the condition were more humid than today. A slight increase in Artemisia at ca. 11–10.5 ¹⁴C kyr BP (13–12 ka) was indicative of the Younger Dryas event. An expansion of birch forests with fir at ca. 12–6.4 ka suggests higher humidity. The currently dominant Scots and Siberian pine forests with birch expanded since 6.4 ka.  相似文献   

Using ocean quahog (<Emphasis Type="Italic">Arctica islandica</Emphasis>) shells to reconstruct palaeoenvironment in Öresund,Kattegat and Skagerrak,Sweden     

Elena Dunca  Harry Mutvei  Peter Göransson  Carl-Magnus Mörth  Bernd R. Schöne  Martin J. Whitehouse  Mikael Elfman  Susanne P. Baden 《International Journal of Earth Sciences》2009,98(1):3-17

Shells of Arctica islandica collected between 1884 and 2004 from Öresund, Kattegat and Skagerrak (Swedish West Coast) were used to monitor local climate variations and the influence of human activities on the local environment. For this purpose, we analysed the growth, structure and chemical composition of these shells and compared them with shells collected from Kiel Bay, Norway and Iceland. The growth rate of the studied shells registers an NAO periodicity of ca 8 years. However, the observed signal is weak because of other environmental interferences that are either of natural or anthropogenic origin. For example, the oxygen isotope ratios show temperature fluctuation, but also the influx of low salinity water. Higher contents of S, N, Cu, Zn, As, Cd and P in shell portions formed during the last century are related to human activities such as mining and industrial development. Our study indicates that in order to use Arctica shells as archives of climate change it is necessary to study the full range of environmental data that is recorded in the shells by using a multi element and isotope approach in combination with different analytical techniques including investigation of growth rates and shell structure.  相似文献   

An OLS regression model for context-aware tile prefetching in a web map cache     

Ricardo García Martín  Juan Pablo de Castro Fernández  Elena Verdú Pérez  María Jesús Verdú Pérez  Luisa María Regueras Santos 《International journal of geographical information science》2013,27(3):614-632

The increasing popularity of web map services has motivated the development of more scalable services in the spatial data infrastructures. Tiled map services have emerged as a scalable alternative to traditional map services. Instead of rendering map images on the fly, a collection of pre-generated image tiles can be served very fast from a server-side cache. However, during the start-up of the service, the cache is initially empty and users experience a poor quality of service. Tile prefetching attempts to improve hit rates by proactively fetching map images without waiting for client requests.

While most popular prefetching policies in traditional web caching consider only the previous access history to make predictions, significant improvements could be achieved in web mapping by taking into account the background geographic information.

This work proposes a regressive model to predict which areas are likely to be requested in the future based on spatial cross-correlation between an unconstrained catalog of geographic features and a record of past cache requests. Tiles that are anticipated to be most frequently requested can be pre-generated and cached for faster retrieval. Trace-driven simulations with several million cache requests from two different nation-wide public web map services in Spain demonstrate that accurate predictions and performance gains can be obtained with the proposed model.  相似文献