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Impact of soil saturated state with water on speciazation of poisonous metals
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《Global Geology》 1998年第1期28-29,共2页
关键词 SOIL Impact of soil saturated state with water on speciazation of poisonous metals
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Maximum Correntropy Kalman Filtering for Non-Gaussian Systems With State Saturations and Stochastic Nonlinearities 被引量:1
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作者 Bo Shen Xuelin Wang Lei Zou 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2023年第5期1223-1233,共11页
This paper tackles the maximum correntropy Kalman filtering problem for discrete time-varying non-Gaussian systems subject to state saturations and stochastic nonlinearities. The stochastic nonlinearities, which take ... This paper tackles the maximum correntropy Kalman filtering problem for discrete time-varying non-Gaussian systems subject to state saturations and stochastic nonlinearities. The stochastic nonlinearities, which take the form of statemultiplicative noises, are introduced in systems to describe the phenomenon of nonlinear disturbances. To resist non-Gaussian noises, we consider a new performance index called maximum correntropy criterion(MCC) which describes the similarity between two stochastic variables. To enhance the “robustness” of the kernel parameter selection on the resultant filtering performance, the Cauchy kernel function is adopted to calculate the corresponding correntropy. The goal of this paper is to design a Kalman-type filter for the underlying systems via maximizing the correntropy between the system state and its estimate. By taking advantage of an upper bound on the one-step prediction error covariance, a modified MCC-based performance index is constructed. Subsequently, with the assistance of a fixed-point theorem, the filter gain is obtained by maximizing the proposed cost function. In addition, a sufficient condition is deduced to ensure the uniqueness of the fixed point. Finally, the validity of the filtering method is tested by simulating a numerical example. 展开更多
关键词 Fixed-point theorem maximum correntropy criterion non-Gaussian noises state saturations stochastic nonlinearities
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A patchy-saturated rock physics model for tight sandstone based on microscopic pore structures 被引量:1
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作者 Wu Chun-Fang Ba Jing +2 位作者 Carcione José M. Müller Tobias M. Zhang Lin 《Applied Geophysics》 SCIE CSCD 2022年第2期147-160,306,共15页
The wave-induced local fluid flow mechanism is relevant to the complex heterogeneity of pore structures in rocks.The analysis of the local fluid flow mechanism is useful for accurately describing the wave propagation ... The wave-induced local fluid flow mechanism is relevant to the complex heterogeneity of pore structures in rocks.The analysis of the local fluid flow mechanism is useful for accurately describing the wave propagation characteristics in reservoir rocks.In the exploration and production of hydrocarbon reservoirs,the real stratum may be partially saturated with a multi-phase fluid mixture in general.Therefore,it is of great significance to investigate the wave velocity dispersion and attenuation features in relation to pore structures and fluids.In this work,the characteristics of fabric microstructures are obtained on the basis of pressure dependency of dry rock moduli using the effective medium theory.A novel anelasticity theoretical model for the wave propagation in a partially-saturated medium is presented by combining the extended Gurevich squirt-flow model and White patchysaturation theory.Numerical simulations are used to analyze wave propagation characteristics that depend on water saturation,external patchy diameter,and viscosity.We consider a tight sandstone from the Qingyang area of the Ordos Basin in west China and perform ultrasonic measurements under partial saturation states and different confining pressures,where the basic properties of the rock are obtained at the full gas saturation.The comparison of experimental data and theoretical modeling results shows a fairly good agreement,indicating that the new theory is effective. 展开更多
关键词 Pore structure patchy saturation state squirt-flow effect wave velocity dispersion and attenuation
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Carbon Solubility and Mass Action Concentrations of Fe-Cr-C Melts
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作者 Jtan Zhang(Metallurgy School, University of Science and Technology Beijing, Beijing 100083, China) 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2000年第2期86-91,共6页
An empirical equation of carbon solubility in Fe-Cr-C melts is regressed based on the experimental data from references. Acalculating model of mass action concentrations for these melts is formulated on the basis of t... An empirical equation of carbon solubility in Fe-Cr-C melts is regressed based on the experimental data from references. Acalculating model of mass action concentrations for these melts is formulated on the basis of the coexistence theory of metaIlic melts in-volving compound formation, the phase diagram of Cr-C system as well as thermodynamic data of Fe-Cr-C melts. According to the mod-el, the standard Gibbs free energies of formation of CrC and Cr3C2 are obtained. Satisfactory agreement between the calculated and me-asured values shows that the model can reflect the structural characteristics of Fe-Cr-C melts. 展开更多
关键词 activity coexistence theory mass action concentration saturated state
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Simulation of global ocean acidification and chemical habitats of shallow-and cold-water coral reefs 被引量:1
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作者 ZHENG Mei-Di CAO Long 《Advances in Climate Change Research》 SCIE 2014年第4期189-196,共8页
Using the UVic Earth System Model, this study simulated the change of seawater chemistry and analyzed the chemical habitat surrounding shallow- and cold-water coral reefs from the year 1800 to 2300 employing RCP2.6, R... Using the UVic Earth System Model, this study simulated the change of seawater chemistry and analyzed the chemical habitat surrounding shallow- and cold-water coral reefs from the year 1800 to 2300 employing RCP2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios. The model results showed that the global ocean will continue to absorb atmospheric CO2. Global mean surface ocean temperature will rise 1.1-2.8 K at the end of the 21st century across RCP scenarios. Meanwhile, the global mean surface ocean pH will drop 0.14--0.42 and the ocean surface mean con- centration of carbonate will decrease 20%--51% across the RCP scenarios. The saturated state of sea water with respect to calcite carbonate minerals (t2) will decrease rapidly. During the pre-industrial period, 99% of the shallow-water coral reefs were surrounded by seawater with t2 〉 3.5 and 87% of the deep-sea coral reefs were surrounded by seawater with aragonite supersaturation. Within the 21st century, except for the high mitigation scenario of RCP2.6, almost none shallow-water coral reefs will be surrounded by seawater with g2 〉 3.5. Under the intensive emission scenario of RCP8.5, by the year 2100, the aragonite saturation horizon will rise to 308 m under the sea surface from 1138 m at the pre- industrial period, thus 73% of the cold-water coral reefs will be surrounded by seawater with aragonite undersaturation. By the year 2300, only 5% of the cold-water coral reefs will be surrounded by seawater with aragonite supersaturation. 展开更多
关键词 Simulation research Aragonite saturation state Ocean acidification Shallow-water coral reefs Cold-water coral reefs
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Processes Controlling the Carbonate Chemistry of Surface Seawater Along the 150°E Transect in the Northwest Pacific Ocean
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作者 MOU Liang ZHANG Honghai +1 位作者 CHEN Zhaohui HU Yubin 《Journal of Ocean University of China》 SCIE CAS CSCD 2022年第6期1529-1537,共9页
The problem of ocean acidification caused by the increase of atmospheric carbon dioxide concentration is becoming increasingly prominent.Field observation in the northwest Pacific Ocean was carried out along the 150&#... The problem of ocean acidification caused by the increase of atmospheric carbon dioxide concentration is becoming increasingly prominent.Field observation in the northwest Pacific Ocean was carried out along the 150°E transect in November 2019.The distribution characteristics and influencing factors of the surface seawater carbonate chemistry,including dissolved inorganic carbon(DIC),total alkalinity(TA),pH,partial pressure of carbon dioxide(pCO_(2))and aragonite saturation state(Ω_(arag))were investigated.DIC and TA ranged from 1915 to 2014μmol kg^(−1)and 2243 to 2291μmol kg^(−1),respectively;DIC in general decreased with decreasing latitude,but TA had no clear latitudinal gradient.pCO_(2)values increased with the decrease of latitude and were all below the atmospheric pCO_(2)level,ranging from 332 to 387μatm.pH on the total hydrogen ion concentration scale(pH_(T))decreased with the decrease of latitude in the range of 8.044–8.110,whileΩ_(arag) increased with the decrease of latitude in the range of 2.61–3.88,suggesting that the spatial distributions of pH_(T) andΩ_(arag) were out of phase.Compared with the present,the predicted values of pH_(T) and Ω_(arag) by the end of this century would decrease remarkedly;larger declines were found in the higher pH_(T) and Ω_(arag) regions,resulting in the differences along the meridional gradient becoming smaller for bothpH_(T) and Ω_(arag). 展开更多
关键词 ocean acidification carbonate system aragonite saturation state seawater pH Pacific Ocean
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Spatial variability of summertime aragonite saturation states and its influencing factor in the Bering Sea 被引量:2
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作者 SUN Heng GAO Zhong-Yong +2 位作者 ZHAO De-Rong SUN Xiu-Wu CHEN Li-Qi 《Advances in Climate Change Research》 SCIE CSCD 2021年第4期508-516,共9页
The Bering sea is susceptible to ocean acidification driven by both human activities(anthropogenic CO_(2))and distinctive natural processes.To assess the situation of ocean acidification,we investigated the spatial va... The Bering sea is susceptible to ocean acidification driven by both human activities(anthropogenic CO_(2))and distinctive natural processes.To assess the situation of ocean acidification,we investigated the spatial variability of aragonite saturation states(ΩAr)in July 2010 during the 4th Chinese National Arctic Research Expedition(CHINARE).The surface waters were all oversaturated with respect to aragonite(ΩAr>1)due to high biological removal,andΩAr ranged from 1.43 to 3.17.The relatively lowΩAr values were found in the western Bering Strait and eastern nearshore region of the Bering Sea Shelf,which were associated with the upwelling and riverine input,respectively.In the subsurface,theΩAr decreased to generally low saturation states and were observed to be strongly undersaturated(ΩAr<1)in the bottom waters with a lowest value of 0.45,which might be caused by remineralization.However,unlike prior studies,the lowΩAr values in the shallow nearshore region were still above the saturation horizon throughout the water column,which were probably counteracted by high local primary production.In the context of climate change and increasing anthropogenic CO_(2)absorption,the suppression and undersaturation ofΩAr in the Bering Sea are not only attributed to the natural processes but also the accumulation of anthropogenic CO_(2). 展开更多
关键词 Bering sea Ocean acidification Aragonite saturation states Spatial variability CONTROLS
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Stability analysis for discrete linear systems with state saturation by a saturation-dependent Lyapunov functional 被引量:2
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作者 Xiaofu JI Mingwei REN +1 位作者 Hongye SU Jinfeng GAO 《控制理论与应用(英文版)》 EI 2012年第4期539-542,共4页
This paper concerns the stability analysis problem of discrete linear systems with state saturation using a saturation-dependent Lyapunov functional. We introduce a free matrix characterized by the sum of the absolute... This paper concerns the stability analysis problem of discrete linear systems with state saturation using a saturation-dependent Lyapunov functional. We introduce a free matrix characterized by the sum of the absolute value of each elements for each row less than 1, which makes the state with saturation constraint reside in a convex polyhedron. A saturation-dependent Lyapunov functional is then designed to obtain a sufficient condition for such systems to be globally asymptotically stable. Based on this stability criterion, the state feedback control law synthesis problem is also studied. The obtained results are formulated in terms of bilinear matrix inequalities that can be solved by the presented iterative linear matrix ineoualitv algorithm. Two numerical examoles are used to demonstrate the effectiveness of the nronosed method_ 展开更多
关键词 Discrete linear systems state saturation Saturation-dependent Iterative linear matrix inequality
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Coexistence states for a cooperative model with saturation
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《Chinese Science Bulletin》 SCIE CAS 1998年第14期1230-1231,共2页
关键词 Coexistence states for a cooperative model with saturation
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Experimental determination of Cd^2+ adsorption mechanism on low-cost biological waste 被引量:3
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作者 Farhah Amalya ISMAIL Ahmad Zaharin ARIS 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2013年第3期356-364,共9页
Carbonate shells have an astonishing ability in the removal of Cd^2+ in a short time period with emphasis on being a low cost adsorbent. In the present study, the sorption capacity of carbonate shells was studied for... Carbonate shells have an astonishing ability in the removal of Cd^2+ in a short time period with emphasis on being a low cost adsorbent. In the present study, the sorption capacity of carbonate shells was studied for Cd^2+ in batch experiments. The influence of different carbonate shell sizes and physico-chemical factors were evaluated and the results were analyzed for its correlation matrices by using Predictive Analytics Software (PASW). The miner- alogy state of aqueous solution regarding the saturation index was simulated using PHREEQC to identify the Cd^2+ uptake mechanism. The Cd uptake rates were calculated as well as Ca^2+, HCO3- concentration, pH, ambient humidity and temperature were measured. Cd2+ removal of 91.52% was achieved after 5 h adsorption. The adsorption efficiencies were significantly influenced by pH as they increased with the increase of pH from acidic solution (5.50±0.02) to slightly alkaline (7.60±0.05). In addition, the mineralogy state of aqueous solution calculated from PHREEQC confirmed that the increment of Ca^2+ and HCO3- concentrations in solution was attributed to the dissolution of carbonate shells. Moreover, the ion exchange adsorption mechanism of Cd^2+ toward Ca^2+ was identified as the process involved in Cd^2+ uptake. 展开更多
关键词 carbonate shell CADMIUM heavy metal adsorption mechanism saturation state
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Exploring seasonal acidification in the Yellow Sea 被引量:4
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作者 Weidong ZHAI 《Science China Earth Sciences》 SCIE EI CAS CSCD 2018年第6期647-658,共12页
The Yellow Sea on the western continental margin of the North Pacific Ocean is of major ecological and economic importance. Four field surveys were conducted during May and November 2012, August 2015, and January 2016... The Yellow Sea on the western continental margin of the North Pacific Ocean is of major ecological and economic importance. Four field surveys were conducted during May and November 2012, August 2015, and January 2016, investigating seasonal variations in dissolved oxygen and carbonate system parameters of this marginal sea. Results showed that the Yellow Sea cold water mass accumulated respiration-induced CO_2 in subsurface and bottom waters in summer and autumn, leading to acidified seawaters with critical carbonate saturation states of aragonite(Ω_(arag)) of less than 1.5. These seriously acidified seawaters occupied one third of surveyed areas in summer and autumn, likely affecting local calcified organisms and benthic communities. In a future scenario for the 2050 s, in which the atmospheric CO_2 mole fraction increases by 100 μmol mol-1, half of the Yellow Sea benthos would be seasonally covered by acidified seawater having a critical Ω_(arag) of less than 1.5. The corresponding bottom-water p H_T would be around 7.85 in summer, and 7.80 in autumn. Of the China seas, the Yellow Sea cold water mass represents one of the ecosystems most vulnerable to ocean acidification. 展开更多
关键词 CaCO_3saturation state Ocean acidification Yellow Sea pH Dissolved oxygen Benthic communities
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A new stability analysis and controller design method for discrete-time linear systems with saturation nonlinearities
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作者 Wei GUAN Guanghong YANG 《控制理论与应用(英文版)》 EI 2011年第4期604-610,共7页
The problems of stability analysis and controllers design for discrete-time linear systems subject to state saturation nonlinearities are investigated in this paper. Both full state saturation and partial state satura... The problems of stability analysis and controllers design for discrete-time linear systems subject to state saturation nonlinearities are investigated in this paper. Both full state saturation and partial state saturation are considered. It is well known to all that the controller design problem under state saturation is very difficult and complex to deal with. In order to overcome the difficulty, a new and tractable system is constructed, and it can be proved that the constructed system is with the same domain of attraction as the original system. With the aid of this property, to estimate the domain of attraction of the original system, an LMI-based method is presented for estimating the domain of attraction of the origin for the new constructed system under state saturation. Further, two optimization algorithms are developed for constructing dynamic output-feedback controllers and state feedback controllers, respectively, which guarantee that the domain of attraction of the origin for the closed-loop system is as 'large' as possible. An example is provided to demonstrate the effectiveness of the new method. 展开更多
关键词 state saturation Linear systems LMIS
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