The concentration of hydrogen sulfide gas （H2S） varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basin...The concentration of hydrogen sulfide gas （H2S） varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H2S concentration has been found in the Ordos Basin, the Songliao Basin and the Junggar Basin. Studies suggest that in China H2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonatedominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H2S is of Thermochemical Sulfate Reduction （TSR） origin. The H2S is of Bacterial Sulphate Reduction （BSR） origin deduced from the waterflooding operation in the Changheng Oilfield （placanticline oil fields） in the Songliao Basin. H2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H2S. The origin identification methods for H2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H2S. The prediction technologies for primary and secondary origin of H2S have been set up separately.展开更多
In recent years, predictions of damage from earthquakes have been made on a prefectural scale, and expectations exist that more detailed damage forecasts should be made even on a city/town/village scale. It is importa...In recent years, predictions of damage from earthquakes have been made on a prefectural scale, and expectations exist that more detailed damage forecasts should be made even on a city/town/village scale. It is important to know detailed ground characteristics to do damage prediction on a fine scale. Using GIS is the best way to communicate this planar disaster prevention information to the general public. Yokohama City is the second largest city in Japan and developed as part of the capital region of Metropolitan Tokyo. Recently, the population of this city has reached about 3,000,000, and economic and cultural facilities, social infrastructure, and residential complexes are concentrated in this city. The capital region, including Yokohama City, was attacked by the 1923 Great Kanto Earthquake (M7.9) and Yokohama City was devastated by this earthquake. From the research so far, it is known that the H/V spectrum obtained from microtremor observation has a good correlation with the ground characteristics. The authors have been conducting high-density tremor observations that have been ongoing since the 1990s, mainly in Kanagawa Prefecture, Japan. Here, we have organized the predominant periods obtained from the observation results for Yokohama City. The entirety of Yokohama City was divided into 250 m × 250 m meshes and their centers were used as microtremor observation sites. Excluding sites that could not be used due to geographical conditions, observations were made at approximately 5700 sites. So, we compared the data obtained separately, such as the period, terrain classification, and amplification characteristics. The distribution maps of predominant periods in Yokohama City show that the city contains a lot of artificially transformed land, and consequently, the distribution of predominant periods is not uniform. However, it can be seen that the periods become gradually longer, moving from the higher elevation eastern part toward the lower elevation western part. Investigation of the site amplification factors and detailed topographical classifications indicates a clear correlation with the predominant period distribution.展开更多
Background: A number of conservation and societal issues require understanding how species are distributed on the landscape, yet ecologists are often faced with a lack of data to develop models at the resolution and e...Background: A number of conservation and societal issues require understanding how species are distributed on the landscape, yet ecologists are often faced with a lack of data to develop models at the resolution and extent desired, resulting in inefficient use of conservation resources.Such a situation presented itself in our attempt to develop waterfowl distribution models as part of a multi-disciplinary team targeting the control of the highly pathogenic H5N1 avian influenza virus in China.Methods: Faced with limited data, we built species distribution models using a habitat suitability approach for China's breeding and non-breeding(hereafter, wintering) waterfowl.An extensive review of the literature was used to determine model parameters for habitat modeling.Habitat relationships were implemented in GIS using land cover covariates.Wintering models were validated using waterfowl census data, while breeding models, though developed for many species, were only validated for the one species with sufficient telemetry data available.Results: We developed suitability models for 42 waterfowl species(30 breeding and 39 wintering) at 1 km resolution for the extent of China, along with cumulative and genus level species richness maps.Breeding season models showed highest waterfowl suitability in wetlands of the high-elevation west-central plateau and northeastern China.Wintering waterfowl suitability was highest in the lowland regions of southeastern China.Validation measures indicated strong performance in predicting species presence.Comparing our model outputs to China's protected areas indicated that breeding habitat was generally better covered than wintering habitat, and identified locations for which additional research and protection should be prioritized.Conclusions: These suitability models are the first available for many of China's waterfowl species, and have direct utility to conservation and habitat planning and prioritizing management of critically important areas, providing an example of how this approach may aid others faced with the challenge of addressing conservation issues with little data to inform decision making.展开更多
By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with di...By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with different orientation angles driven by elliptically polarized laser pulse with varying ellipticities. Our numerical results show that the MPMD is sensitive to the orientation angle and the laser ellipticity, which can be explained by the attosecond perturbation ionization theory and the exactly solvable photoionization model. When the ellipticity ε = 0, the final MPMD of x-oriented H^+_2 shows a distinct six-lobe pattern that is different from that with ε = 0.5 and ε = 1. The evolutions of electron wave packet(EWP)and MPMD with x-oriented H^+_2 are presented to interpret this distinct pattern.展开更多
Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded (Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on the ab initio 6-31G basis set calculati...Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded (Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on the ab initio 6-31G basis set calculations,the properties of the charge density for the complexeshave been analyzed using the theory of atoms in molecules.The nature of the complex formation has been discussed in terms of the properties of the charge density distributions.展开更多
Analysis on the space group distribution in 78 substituted phenols re-vealed its unusual high frequencies in groups with non-centrosymmetry or polar axis orhigher symmetry or Z' > 1. Based on the characteristic...Analysis on the space group distribution in 78 substituted phenols re-vealed its unusual high frequencies in groups with non-centrosymmetry or polar axis orhigher symmetry or Z' > 1. Based on the characteristics of intermolecular H-bondsformed by two OH groups,the space group distribution could be rationalized well.展开更多
It is known from the New Energy and Industry Technology Development Organization (NEDO) roam map Japan, 2017 that the polymer electrolyte fuel cell (PEFC) power generation system is required to operate at 100°C f...It is known from the New Energy and Industry Technology Development Organization (NEDO) roam map Japan, 2017 that the polymer electrolyte fuel cell (PEFC) power generation system is required to operate at 100°C for application of mobility usage from 2020 to 2025. This study aims to clarify the effect of separator thickness on the distribution of the temperature of reaction surface (T<sub>react</sub>) at the initial temperature of cell (T<sub>ini</sub>) with flow rate, relative humidity (RH) of supply gases as well as RH of air surrounding cell of PEFC. The distribution of T<sub>react</sub> is estimated by means of the heat transfer model considering the H<sub>2</sub>O vapor transfer proposed by the authors. The relationship between the standard deviation of T<sub>react</sub>-T<sub>ini</sub> and total voltage obtained in the experiment is also investigated. We can know the effect of the flow rate of supply gas as well as RH of air surrounding cell of PEFC on the distribution of T<sub>react</sub>-T<sub>ini</sub> is not significant. It is observed the wider distribution of T<sub>react</sub>-T<sub>ini</sub> provides the reduction in power generation performance irrespective of separator thickness. In the case of separator thickness of 1.0 mm, the standard deviation of T<sub>react</sub>-T<sub>ini</sub> has smaller distribution range and the total voltage shows a larger variation compared to the other cases.展开更多
In order to keep stable navigation accuracy when the blind node （BN） moves between two adjacent clusters, a distributed fusion method for the integration of the inertial navigation system （INS） and the wireless se...In order to keep stable navigation accuracy when the blind node （BN） moves between two adjacent clusters, a distributed fusion method for the integration of the inertial navigation system （INS） and the wireless sensor network （WSN） based on H∞ filtering is proposed. Since the process and measurement noise in the integration system are bounded and their statistical characteristics are unknown, the H∞ filter is used to fuse the information measured from local estimators in the proposed method. Meanwhile, the filter can yield the optimal state estimate according to certain information fusion criteria. Simulation results show that compared with the federal Kalman solution, the proposed method can reduce the mean error of position by about 45% and the mean error of velocity by about 85 %.展开更多
The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was studied.In addition,the inward movement Reynold...The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was studied.In addition,the inward movement Reynolds number and inward movement time of oxide inclusions as well as the solidification time of molten steel at different positions in the castings were calculated to clarify the removal mechanism of oxide inclusions in super-gravity field.The results show that the large size(i.e.,greater than 10μm)oxide inclusions are mainly concentrated in the inner and outer parts of the super-gravity castings with constant rotation speed(500 r min^(-1))and five-stage rotation speeds(500,600,750,850,and 950 r min^(-1)),respectively,while there are no large oxide inclusions in the super-gravity castings with three-stage rotation speeds(500,600,and 750 r min^(-1)).Although an increase in the particle size of inclusion and the rotation speed in super-gravity field is conducive to the increase in the inward movement Reynolds number of oxide inclusions and reduction in the inward movement time of oxide inclusions,it will reduce the local solidification time of molten steel.In the range of the rotation speed studied,the super-gravity field with three-stage rotation speeds has the best effect on the removal of inclusions in H13 molten steel.展开更多
This paper deals with H∞ state estimation problem of neural networks with discrete and distributed time-varying delays. A novel delay-dependent concept of H∞ state estimation is proposed to estimate the H∞ performa...This paper deals with H∞ state estimation problem of neural networks with discrete and distributed time-varying delays. A novel delay-dependent concept of H∞ state estimation is proposed to estimate the H∞ performance and global asymptotic stability of the concerned neural networks. By constructing the Lyapunov-Krasovskii functional and using the linear matrix inequality technique, sufficient conditions for delay-dependent H∞ performances are obtained, which can be easily solved by some standard numerical algorithms. Finally, numerical examples are given to illustrate the usefulness and effectiveness of the proposed theoretical results.展开更多
In this paper, the robust H∞control problem for a class of stochastic systems with interval time-varying and distributed delays is discussed. The system under study involves parameter uncertainty, stochastic disturba...In this paper, the robust H∞control problem for a class of stochastic systems with interval time-varying and distributed delays is discussed. The system under study involves parameter uncertainty, stochastic disturbance, interval time-varying,and distributed delay. The aim is to design a delay-dependent robust H∞control which ensures the robust asymptotic stability of the given system and to express it in the form of linear matrix inequalities（LMIs）. Numerical examples are given to demonstrate the effectiveness of the proposed method. The results are also compared with the existing results to show its conservativeness.展开更多
目的:系统评价我国H型高血压中医证型分布频率。方法:对PubMed、Web of science、维普中文期刊数据库、万方数据知识服务平台数据库、中国国家知识基础设施数据库进行检索。检索时限均为建库至2022年11月4日。结果:共纳入18篇合格中文文...目的:系统评价我国H型高血压中医证型分布频率。方法:对PubMed、Web of science、维普中文期刊数据库、万方数据知识服务平台数据库、中国国家知识基础设施数据库进行检索。检索时限均为建库至2022年11月4日。结果:共纳入18篇合格中文文献,无英文文献,纳入研究对象共4 020例。Meta分析结果显示,肝火亢盛证分布频率为0.21[95%置信区间(CI)(0.18,0.23)],阴虚阳亢证分布频率为0.23[95%CI(0.18,0.29)],痰湿壅盛证分布频率为0.35[95%CI(0.30,0.40)],阴阳两虚证分布频率为0.19[95%CI (0.14,0.26)]。亚组分析显示:在文献质量评价亚组中,痰湿壅盛证在分布情况上的差异有统计学意义(P <0.05),其余证型在分布情况上的差异无统计学意义(P> 0.05);肝火亢盛证、阴虚阳亢证、痰湿壅盛证、阴阳两虚证的分布情况在南北地域方面的差异无统计学意义(P> 0.05)。结论:我国的H型高血压证型分布由少到多依次为阴阳两虚证、肝火亢盛证、阴虚阳亢证、痰湿壅盛证;其中痰湿壅盛证与H型高血压之间密切相关,并且可能为H型高血压的高危证型。由于受到纳入研究数量、质量的影响,以及有发表偏倚存在的可能,上述结论需要通过进一步扩大样本量及纳入更多高质量的研究加以验证。展开更多
文摘目的 探讨免疫性血小板输注无效(PTR)患者HLA/HPA抗体特异性分布特征及其对血小板输注效果的影响。方法 本研究以86例免疫性PTR患者为研究对象,收集其性别、年龄、身高、体重、配血次数、疾病类型、输注前后血小板计数等临床资料,通过微珠法进行HLA特异性抗体的检测,并分析抗体特性对血小板输注效果的影响。结果 86例PTR患者中,单独HLA抗体、单独HPA抗体、HLA+HPA抗体阳性的患者分别为72例(83.72%)、8例(9.30%)、6例(6.98%)。HLA抗体在各位点中检出频率最高的抗体对应等位基因分别为A*25:01、B*15:12、C*02:02(和C*17:01),检出率分别为81.48%、87.04%、48.15%;而对应抗原表位出现频率最高的前三位为163LG、97V、71ATD,检出率分别为87.04%、77.78%、74.07%。仅存在HLA抗体的患者,输注交叉配型相合血小板的24 h血小板计数纠正增加指数(CCI)及输注有效情况均明显优于随机血小板(P<0.01)。在血小板交叉配型阴性结果的患者中,HLA抗体强度与交叉配型相合血小板的24 h CCI值及输注有效情况呈负相关关系,强度越高,输注效果越差(P<0.01)。HLA抗体强度为中、低等水平的患者,输注交叉配型相合血小板的24 h CCI值及输注有效情况均优于输注随机血小板(P<0.05)。结论 本研究所得到的PTR患者HLA/HPA抗体特性及其对血小板输注效果影响的结果,可为血小板库建立时供者的选择提供指导,同时对临床PTR患者的治疗方式选择有一定的参考价值。
基金supported by the National Natural Science Foundation of China (Grant Nos 4060201640773032)the National Basic Research Program of China (contract No.2007CB209500)
文摘The concentration of hydrogen sulfide gas （H2S） varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H2S concentration has been found in the Ordos Basin, the Songliao Basin and the Junggar Basin. Studies suggest that in China H2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonatedominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H2S is of Thermochemical Sulfate Reduction （TSR） origin. The H2S is of Bacterial Sulphate Reduction （BSR） origin deduced from the waterflooding operation in the Changheng Oilfield （placanticline oil fields） in the Songliao Basin. H2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H2S. The origin identification methods for H2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H2S. The prediction technologies for primary and secondary origin of H2S have been set up separately.
文摘In recent years, predictions of damage from earthquakes have been made on a prefectural scale, and expectations exist that more detailed damage forecasts should be made even on a city/town/village scale. It is important to know detailed ground characteristics to do damage prediction on a fine scale. Using GIS is the best way to communicate this planar disaster prevention information to the general public. Yokohama City is the second largest city in Japan and developed as part of the capital region of Metropolitan Tokyo. Recently, the population of this city has reached about 3,000,000, and economic and cultural facilities, social infrastructure, and residential complexes are concentrated in this city. The capital region, including Yokohama City, was attacked by the 1923 Great Kanto Earthquake (M7.9) and Yokohama City was devastated by this earthquake. From the research so far, it is known that the H/V spectrum obtained from microtremor observation has a good correlation with the ground characteristics. The authors have been conducting high-density tremor observations that have been ongoing since the 1990s, mainly in Kanagawa Prefecture, Japan. Here, we have organized the predominant periods obtained from the observation results for Yokohama City. The entirety of Yokohama City was divided into 250 m × 250 m meshes and their centers were used as microtremor observation sites. Excluding sites that could not be used due to geographical conditions, observations were made at approximately 5700 sites. So, we compared the data obtained separately, such as the period, terrain classification, and amplification characteristics. The distribution maps of predominant periods in Yokohama City show that the city contains a lot of artificially transformed land, and consequently, the distribution of predominant periods is not uniform. However, it can be seen that the periods become gradually longer, moving from the higher elevation eastern part toward the lower elevation western part. Investigation of the site amplification factors and detailed topographical classifications indicates a clear correlation with the predominant period distribution.
基金supported by the United States Geological Survey(Ecosystems Mission Area)the National Science Foundation Small Grants for Exploratory Research(No.0713027)Wetlands International
文摘Background: A number of conservation and societal issues require understanding how species are distributed on the landscape, yet ecologists are often faced with a lack of data to develop models at the resolution and extent desired, resulting in inefficient use of conservation resources.Such a situation presented itself in our attempt to develop waterfowl distribution models as part of a multi-disciplinary team targeting the control of the highly pathogenic H5N1 avian influenza virus in China.Methods: Faced with limited data, we built species distribution models using a habitat suitability approach for China's breeding and non-breeding(hereafter, wintering) waterfowl.An extensive review of the literature was used to determine model parameters for habitat modeling.Habitat relationships were implemented in GIS using land cover covariates.Wintering models were validated using waterfowl census data, while breeding models, though developed for many species, were only validated for the one species with sufficient telemetry data available.Results: We developed suitability models for 42 waterfowl species(30 breeding and 39 wintering) at 1 km resolution for the extent of China, along with cumulative and genus level species richness maps.Breeding season models showed highest waterfowl suitability in wetlands of the high-elevation west-central plateau and northeastern China.Wintering waterfowl suitability was highest in the lowland regions of southeastern China.Validation measures indicated strong performance in predicting species presence.Comparing our model outputs to China's protected areas indicated that breeding habitat was generally better covered than wintering habitat, and identified locations for which additional research and protection should be prioritized.Conclusions: These suitability models are the first available for many of China's waterfowl species, and have direct utility to conservation and habitat planning and prioritizing management of critically important areas, providing an example of how this approach may aid others faced with the challenge of addressing conservation issues with little data to inform decision making.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11271158,11574117,and 61575077)the Natural Science Foundation of Jilin Province of China(Grants No.20180101225JC)
文摘By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with different orientation angles driven by elliptically polarized laser pulse with varying ellipticities. Our numerical results show that the MPMD is sensitive to the orientation angle and the laser ellipticity, which can be explained by the attosecond perturbation ionization theory and the exactly solvable photoionization model. When the ellipticity ε = 0, the final MPMD of x-oriented H^+_2 shows a distinct six-lobe pattern that is different from that with ε = 0.5 and ε = 1. The evolutions of electron wave packet(EWP)and MPMD with x-oriented H^+_2 are presented to interpret this distinct pattern.
基金Projeet supported by the National Natural Science Foundation of China.
文摘Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded (Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on the ab initio 6-31G basis set calculations,the properties of the charge density for the complexeshave been analyzed using the theory of atoms in molecules.The nature of the complex formation has been discussed in terms of the properties of the charge density distributions.
文摘Analysis on the space group distribution in 78 substituted phenols re-vealed its unusual high frequencies in groups with non-centrosymmetry or polar axis orhigher symmetry or Z' > 1. Based on the characteristics of intermolecular H-bondsformed by two OH groups,the space group distribution could be rationalized well.
文摘It is known from the New Energy and Industry Technology Development Organization (NEDO) roam map Japan, 2017 that the polymer electrolyte fuel cell (PEFC) power generation system is required to operate at 100°C for application of mobility usage from 2020 to 2025. This study aims to clarify the effect of separator thickness on the distribution of the temperature of reaction surface (T<sub>react</sub>) at the initial temperature of cell (T<sub>ini</sub>) with flow rate, relative humidity (RH) of supply gases as well as RH of air surrounding cell of PEFC. The distribution of T<sub>react</sub> is estimated by means of the heat transfer model considering the H<sub>2</sub>O vapor transfer proposed by the authors. The relationship between the standard deviation of T<sub>react</sub>-T<sub>ini</sub> and total voltage obtained in the experiment is also investigated. We can know the effect of the flow rate of supply gas as well as RH of air surrounding cell of PEFC on the distribution of T<sub>react</sub>-T<sub>ini</sub> is not significant. It is observed the wider distribution of T<sub>react</sub>-T<sub>ini</sub> provides the reduction in power generation performance irrespective of separator thickness. In the case of separator thickness of 1.0 mm, the standard deviation of T<sub>react</sub>-T<sub>ini</sub> has smaller distribution range and the total voltage shows a larger variation compared to the other cases.
基金The National Basic Research Program of China (973 Program) (No. 2009CB724002)the National Natural Science Foundation of China (No. 50975049)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20110092110039)the Program for Special Talents in Six Fields of Jiangsu Province (No.2008143)the Program Sponsored for Scientific Innovation Research of College Graduates in Jiangsu Province,China (No. CXLX_0101)
文摘In order to keep stable navigation accuracy when the blind node （BN） moves between two adjacent clusters, a distributed fusion method for the integration of the inertial navigation system （INS） and the wireless sensor network （WSN） based on H∞ filtering is proposed. Since the process and measurement noise in the integration system are bounded and their statistical characteristics are unknown, the H∞ filter is used to fuse the information measured from local estimators in the proposed method. Meanwhile, the filter can yield the optimal state estimate according to certain information fusion criteria. Simulation results show that compared with the federal Kalman solution, the proposed method can reduce the mean error of position by about 45% and the mean error of velocity by about 85 %.
基金This work was financially supported by China Postdoctoral Fund(No.2021M700394)Key R&D Plan of Shandong Province in 2021(No.2021CXGC010209).The authors thank the Beijing Key Laboratory of Special Melting and Preparation of High-end Metal Materials for its support.The authors wish to thank the timely help given by Li-hui Han in University of Science and Technology Beijing.
文摘The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was studied.In addition,the inward movement Reynolds number and inward movement time of oxide inclusions as well as the solidification time of molten steel at different positions in the castings were calculated to clarify the removal mechanism of oxide inclusions in super-gravity field.The results show that the large size(i.e.,greater than 10μm)oxide inclusions are mainly concentrated in the inner and outer parts of the super-gravity castings with constant rotation speed(500 r min^(-1))and five-stage rotation speeds(500,600,750,850,and 950 r min^(-1)),respectively,while there are no large oxide inclusions in the super-gravity castings with three-stage rotation speeds(500,600,and 750 r min^(-1)).Although an increase in the particle size of inclusion and the rotation speed in super-gravity field is conducive to the increase in the inward movement Reynolds number of oxide inclusions and reduction in the inward movement time of oxide inclusions,it will reduce the local solidification time of molten steel.In the range of the rotation speed studied,the super-gravity field with three-stage rotation speeds has the best effect on the removal of inclusions in H13 molten steel.
基金Supported by National Basic Research Program of China （973 Program） （2010CB731800） and National Natural Science Foundation of China （60974059, 60736026, 61021063）
基金supported by the Fund from National Board of Higher Mathematics(NBHM),New Delhi(Grant No.2/48/10/2011-R&D-II/865)
文摘This paper deals with H∞ state estimation problem of neural networks with discrete and distributed time-varying delays. A novel delay-dependent concept of H∞ state estimation is proposed to estimate the H∞ performance and global asymptotic stability of the concerned neural networks. By constructing the Lyapunov-Krasovskii functional and using the linear matrix inequality technique, sufficient conditions for delay-dependent H∞ performances are obtained, which can be easily solved by some standard numerical algorithms. Finally, numerical examples are given to illustrate the usefulness and effectiveness of the proposed theoretical results.
基金Project supported by the Fund from the Department of Science and Technology(DST)(Grant No.SR/FTP/MS-039/2011)
文摘In this paper, the robust H∞control problem for a class of stochastic systems with interval time-varying and distributed delays is discussed. The system under study involves parameter uncertainty, stochastic disturbance, interval time-varying,and distributed delay. The aim is to design a delay-dependent robust H∞control which ensures the robust asymptotic stability of the given system and to express it in the form of linear matrix inequalities（LMIs）. Numerical examples are given to demonstrate the effectiveness of the proposed method. The results are also compared with the existing results to show its conservativeness.
