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
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
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
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
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
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
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
基金the National Key Research and Development Program of China(2019YFA0607003)Scientific Research Foundation of Third Institute of Oceanography,MNR(2018005,2020017)+2 种基金National Natural Science Foundation of China(41406221,41476173)the Chinese Projects for Investigations and Assessments of the Arctic and Antarctic(CHINARE2017-2021)Fujian science and technology innovation leader project 2016.
文摘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).
基金supported in part by the National Natural Science Foundation of China (62273088, 62273087)the Shanghai Pujiang Program of China (22PJ1400400)the Program of Shanghai Academic/Technology Research Leader (20XD1420100)。
文摘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.
基金supported by the Key Research and Development Program of Shandong Province(No.2020 ZLYS04)the National Key Research and Development Program of China(No.2017YFA0604300)+2 种基金the Qingdao Pilot National Laboratory for Marine Science and Technology(No.2018SDKJ0105-1)the Fundamental Research Funds for the Central Universities(No.202072001)the Young Scholars Program of Shandong University(No.2018WLJH43).
文摘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).
文摘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.
基金supported by the National Natural Science Foundation of China(Nos.60904011,61004034,61104016)the Doctoral Fund of Ministry of Education of China(No.20093227120010)+1 种基金the Natural Science Foundation of Jiangsu Province,China(No.BK2011465)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.201106)
文摘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_
基金partly supported by the Funds for Creative Research Groups of China (No. 60821063)National 973 Program of China (No.2009CB320604)+4 种基金the Funds of National Science of China (No. 60974043, 60904010, 60804024, 61074090)the 111 Project (No. B08015)the Funds of Doctoral Program of Ministry of Education, China (20100042110027)a Foundation for the Author of National Excellent Doctoral Dissertation of PR China (No. 201157)the Liaoning Education Department Plan Project of China (No. L2010426)
文摘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.
文摘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.