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pNK289衍生质粒在芽孢杆菌中的分离稳定性 被引量:1
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作者 赵芳懿 白艳玲 +1 位作者 张秀明 高才昌 《微生物学通报》 CAS CSCD 北大核心 2001年第2期50-55,共6页
报道关于一系列pNK289衍生质粒分离稳定性研究结果。这些起源相同的质粒在Baci-llus.subtilisASI.1176中的分离稳定性存在差异,这种差异与质粒的大小和复制方式无关,而与质粒的拷贝数有一定的关系。... 报道关于一系列pNK289衍生质粒分离稳定性研究结果。这些起源相同的质粒在Baci-llus.subtilisASI.1176中的分离稳定性存在差异,这种差异与质粒的大小和复制方式无关,而与质粒的拷贝数有一定的关系。由于不稳定质粒pNK219在B.subtilis BD224宿主中能稳定遗传,所以推测宿主的遗传背景可能影响质粒的分离稳定性。这些研究不仅为进一步寻找与PNK289衍生质粒稳定性相关的基因奠定了基础,而且为在芽孢杆中构建稳定的重组质粒提供了理论依据。 展开更多
关键词 质粒 芽孢杆菌 分离稳定性
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产腈水合酶重组大肠杆菌的质粒稳定性研究 被引量:12
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作者 史悦 于慧敏 +1 位作者 田卓玲 沈忠耀 《中国生物工程杂志》 CAS CSCD 北大核心 2005年第8期70-75,共6页
成功构建了腈水合酶(nitrile hydratase,NHase)高表达的重组大肠杆菌E.coliBL21(DE3)/pETNHM(Kanr),研究了重组质粒pETNHM在重组菌株中的质粒稳定性。结果表明,pETNHM具有较好的结构稳定性,连续传代60代后质粒的基因序列没有明显缺失,... 成功构建了腈水合酶(nitrile hydratase,NHase)高表达的重组大肠杆菌E.coliBL21(DE3)/pETNHM(Kanr),研究了重组质粒pETNHM在重组菌株中的质粒稳定性。结果表明,pETNHM具有较好的结构稳定性,连续传代60代后质粒的基因序列没有明显缺失,且能够正常表达腈水合酶。pETNHM具有分离不稳定性,在无抗生素选择压力下,连续传代48代后质粒丢失的无质粒细胞开始出现。琼脂糖凝胶电泳定量分析表明,2/3的质粒pETNHM以二聚体形式存在,导致质粒拷贝数的下降。进一步研究表明,重组细胞的连续高速分裂及腈水合酶的高表达也会造成质粒拷贝数的下降,从而降低其分离稳定性。反之,重组菌株相对于宿主菌株的较高比生长速率有利于保持含质粒细胞的生长优势,卡那霉素的选择压力则能够保证质粒的稳定遗传。 展开更多
关键词 腈水合酶 重组大肠杆茵 质粒稳定性 分离稳定性 质粒拷贝数 重组大肠杆菌 稳定性研究 大肠杆菌E.coli 琼脂糖凝胶电泳 重组菌株
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花椒(Zanthoxylum bungeamun)种植年限对土壤有机碳矿化拟合及化学分离稳定性碳的影响 被引量:4
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作者 龙健 廖洪凯 +3 位作者 李娟 张文娟 赵畅 张明江 《生态学杂志》 CAS CSCD 北大核心 2018年第4期1111-1119,共9页
以贵州西南部典型石漠化治理示范区内5、17、30年生花椒(Zanthoxylum bungeamun)林土壤为研究对象,以乔木林(约60年)土壤为对照,采用方程拟合的方法研究土壤有机碳矿化动态变化,并探讨种植花椒对土壤有机碳矿化拟合和化学分离稳定性碳... 以贵州西南部典型石漠化治理示范区内5、17、30年生花椒(Zanthoxylum bungeamun)林土壤为研究对象,以乔木林(约60年)土壤为对照,采用方程拟合的方法研究土壤有机碳矿化动态变化,并探讨种植花椒对土壤有机碳矿化拟合和化学分离稳定性碳的影响。结果表明:土壤有机碳矿化数据与双指数方程的拟合效果良好,相关系数均达到0.95以上,土壤缓效性碳含量(Cs)与土壤有机碳累计矿化量(Cmin)的相关性达到了极显著水平(R=0.792,P<0.01);Na2S2O8残留物有机碳含量在各土层均以乔木林最高,约24.5±0.7 g·kg-1,占土壤总有机碳(SOC)的79.5%;H_2O_2残留物有机碳含量及其占SOC百分比在0~15 cm和30~50 cm层分别以30年生花椒林(PO-30)和17年生花椒林(PO-17)最高,分别为7.59±0.8 g·kg-1、26.6%和6.41 g·kg-1、40.1%;HF溶解性有机碳含量及其占SOC的百分比在各土层均以PO-17最高;4种林型的土壤活性有机碳含量仅占缓效性碳含量的1.6%~29.3%,且缓效性碳含量与培养92天土壤有机碳累积矿化量相接近,但缓效性有机碳矿化速率(ks)的变化波动较小(0.013~0.025),且以30年生花椒林土壤的0~15 cm、15~30 cm层最高。随着种植年限的增加,土壤活性有机碳和缓效性有机碳含量整体分别表现出递增和递减的趋势。因此,合理的花椒种植年限能够改善土壤质量及固碳能力,为石漠化土壤的修复提供一定参照。 展开更多
关键词 喀斯特石漠化地区 花椒 土壤有机碳矿化 方程拟合 化学分离稳定性
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深部开采复合顶板离层稳定性判别 被引量:21
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作者 吴德义 闻广坤 王爱兰 《采矿与安全工程学报》 EI 北大核心 2011年第2期252-257,共6页
为研究深部开采复合顶板力学机理,分析离层稳定性判别标准及依据,采用数值模拟方法分析了不同条件复合顶板结构面剪应力、法向拉应力和离层分布特点.结果表明:法向拉应力是结构面中部离层的主要原因,可用法向拉应力作用范围作为结构面... 为研究深部开采复合顶板力学机理,分析离层稳定性判别标准及依据,采用数值模拟方法分析了不同条件复合顶板结构面剪应力、法向拉应力和离层分布特点.结果表明:法向拉应力是结构面中部离层的主要原因,可用法向拉应力作用范围作为结构面离层范围,并作为离层稳定性判别标准,结构面离层范围及其离层值分布具有相关性,结构面离层范围扩展使结构面不同位置离层值分布趋于均匀,但对结构面最大离层值影响并不显著,以离层值作为离层稳定性判据时,应采用允许离层范围两端离层实测值与临界值进行比较来判别. 展开更多
关键词 结构面法向拉应力 结构面分离范围 结构面分离稳定性 离层分布 离层临界值
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正负反馈交替论模型及应用
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作者 林屹 严洪森 《系统工程学报》 CSCD 北大核心 2018年第6期732-744,共13页
针对一些系统状态呈现"平稳→剧变→再平稳→再剧变"的演变规律,提出了正负反馈交替论的动态数学模型及其建模方法.该正负反馈交替论模型引入等效正负反馈,根据数据的变化剧烈程度,将状态稳定性分离,用叠加多个死区函数来反... 针对一些系统状态呈现"平稳→剧变→再平稳→再剧变"的演变规律,提出了正负反馈交替论的动态数学模型及其建模方法.该正负反馈交替论模型引入等效正负反馈,根据数据的变化剧烈程度,将状态稳定性分离,用叠加多个死区函数来反映系统状态在不同剧变期由于能量爆发造成的正反馈作用,能够在无需系统内在机理的情况下,建立系统的动力学方程.最后,以状态变化具有典型"平稳→剧变→再平稳→再剧变"过程的时间序列为例,进行仿真,结果表明了方法的有效性. 展开更多
关键词 正负反馈交替论 时间序列 多维泰勒网 稳定性分离
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Synthesis,characterization and photocatalytic performance of rod-shaped Pt/PbWO_4 composite microcrystals 被引量:6
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作者 余长林 白羽 +3 位作者 何洪波 范文宏 朱丽华 周晚琴 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2015年第12期2178-2185,共8页
Rod-shaped PbW O4 microcrystals of length 1 μm were fabricated by a hydrothermal route and subsequent calcination. Pt nanoparticles(NPs) of different contents(0.5 wt%,1 wt% and 2 wt%) were subsequently deposited ... Rod-shaped PbW O4 microcrystals of length 1 μm were fabricated by a hydrothermal route and subsequent calcination. Pt nanoparticles(NPs) of different contents(0.5 wt%,1 wt% and 2 wt%) were subsequently deposited on the PbW O4 microcrystals,producing robust Pt/PbW O4 composite microcrystals. The PbW O4 microcrystals and Pt/PbW O4 photocatalysts were characterized by X-ray diffraction,N2 sorption measurements,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron,photoluminescence,Fourier-transform infrared,and ultraviolet-visible diffuse reflectance spectroscopies. The photocatalytic performances of the catalysts were evaluated by the consecutive photocatalytic degradation of acid orange II dye. The Pt/PbW O4 composite microcrystals exhibited high photocatalytic activity and stability. The deposition of Pt NPs produced surface plasmon resonance(SPR),which induced a large visible light absorption. A Pt NP content of 1-2 wt% resulted in an ~2 times increase in photocatalytic activity,compared with the activity of Pt/PbW O4. The crystal structure and high crystallinity of PbW O4 resulted in its favorable photocatalytic property,and the SPR effect of the Pt NPs promoted visible light harvesting. The Pt NPs also enhanced the separation of photo-generated electrons and holes,which further promoted the photocatalytic reaction. 展开更多
关键词 Rod-shaped Lead tungstate microcrystals Platium nanoparticles Photocatalytic activity Photocatalytic stability Surface plasma Electron-hole separation
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Analysis and evaluation on pressure fluctuations in air dense medium fluidized bed 被引量:4
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作者 Sheng Cheng Duan Chenlong +2 位作者 Zhao Yuemin Dong Liang Luo Zhenfu 《International Journal of Mining Science and Technology》 EI CSCD 2018年第3期461-467,共7页
Pressure fluctuations contribute to the instability of separation process in air dense medium fluidized bed, which provides a high motivation for further study of underlying mechanisms. Reasons for generation and prop... Pressure fluctuations contribute to the instability of separation process in air dense medium fluidized bed, which provides a high motivation for further study of underlying mechanisms. Reasons for generation and propagation of pressure fluctuations in the air dense medium fluidized bed have been discussed.Drift rate and collision rate of particles were employed to deduce the correlation between voidage and pressure fluctuations. Simultaneously, a dynamic pressure fluctuation measuring and analysis system was established. Based on frequency domain analysis and wavelet analysis, collected signals were disassembled and analyzed. Results show gradually intensive motion of particles increases magnitudes of signal components with lower frequencies. As a result of violent particle motion, the magnitude of real pressure signal's frequency experienced an increase as air velocity increased moderately. Wavelet analysis keeps edge features of the real signal and eliminates the noise efficaciously. The frequency of denoised signal is closed to that of pressure signal identified in frequency domain analysis. 展开更多
关键词 Air dense medium fluidized bed Pressure fluctuations Frequency domain analysis Wavelet analysis Particle distribution function
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Stability analysis of discrete-time BAM neural networks based on standard neural network models 被引量:1
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作者 张森林 刘妹琴 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2005年第7期689-696,共8页
To facilitate stability analysis of discrete-time bidirectional associative memory (BAM) neural networks, they were converted into novel neural network models, termed standard neural network models (SNNMs), which inte... To facilitate stability analysis of discrete-time bidirectional associative memory (BAM) neural networks, they were converted into novel neural network models, termed standard neural network models (SNNMs), which interconnect linear dynamic systems and bounded static nonlinear operators. By combining a number of different Lyapunov functionals with S-procedure, some useful criteria of global asymptotic stability and global exponential stability of the equilibrium points of SNNMs were derived. These stability conditions were formulated as linear matrix inequalities (LMIs). So global stability of the discrete-time BAM neural networks could be analyzed by using the stability results of the SNNMs. Compared to the existing stability analysis methods, the proposed approach is easy to implement, less conservative, and is applicable to other recurrent neural networks. 展开更多
关键词 Standard neural network model (SNNM) Bidirectional associative memory (BAM) Linear matrix inequality (LMI) STABILITY Generalized eigenvalue problem (GEVP)
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Synergistic effects of CuO and Au nanodomains on Cu_2O cubes for improving photocatalytic activity and stability 被引量:5
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作者 Denghui Jiang Yuegang Zhang Xinheng Li 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第1期105-113,共9页
Cu2O is a promising photocatalyst,but it suffers from poor photocatalytic activity and stability,especially for Cu2O cubes.Herein,we report the deposition of CuO and Au nanodomains on Cu2O cubes to form dual surface h... Cu2O is a promising photocatalyst,but it suffers from poor photocatalytic activity and stability,especially for Cu2O cubes.Herein,we report the deposition of CuO and Au nanodomains on Cu2O cubes to form dual surface heterostructures(HCs)to improve photocatalytic activity and stability.The apparent quantum efficiency of Au/CuO/Cu2O HCs was ca.123 times that of pristine Cu2O.In addition,the Au/CuO/Cu2O HCs maintained nearly 80%of its original activity after eight cycles in contrast to five cycles for the Au/Cu2O material.Therefore,CuO and Au domains greatly improved the photocatalytic activity and stability of the Cu2O cubes due to the synergistic effect of the HCs. 展开更多
关键词 Cuprous oxide Photocatalytic activity STABILITY Sequential surface engineering Charge transfer
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A Novel Dense Mixed-Conducting Membrane for Oxygen Permeation 被引量:1
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作者 徐南平 李世光 +1 位作者 金万勤 时钧 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2000年第3期218-223,共6页
Perovskite type SrCo0.4Fe0.6O3-δ(SCF) membrane and a novel perovskite-related ZrO2 doped SrCo0.4Fe0.6O3-δ(SCFZ) membrane were successfully prepared by isostatic pressing. The sintered membranes were characterized b... Perovskite type SrCo0.4Fe0.6O3-δ(SCF) membrane and a novel perovskite-related ZrO2 doped SrCo0.4Fe0.6O3-δ(SCFZ) membrane were successfully prepared by isostatic pressing. The sintered membranes were characterized by high-temperature X-ray diffraction (HTXRD) and energy dispersive spectroscopy (EDS). The oxygen permeabilities of membranes have been measured in the temperature range of 923 K to 1243 K. The oxygen permeation flux at 1123K and activation energy of SCFZ membrane with the thickness of 2mm are respectively 2.68×10^-7 mol·cm^-2·min^-1 and 97.76 kJ·mol^-1. The results of HTXRD in argon atmosphere and the oxygen permeation experiment indicate that the SCFZ membrane is stable at elevated temperature and low oxygen partial pressure. 展开更多
关键词 dense membrane perovskite-related oxygen permeation stability
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Mechanical response and stability analysis of rock mass in high geostress underground powerhouse caverns subjected to excavation 被引量:18
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作者 LI Biao DING Quan-fu +4 位作者 XU Nu-wen LEI Yi-fan XU Yuan ZHU Zhong-ping LIU Jing-fei 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第10期2971-2984,共14页
To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numeric... To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns. 展开更多
关键词 high geostress underground powerhouse caverns microseismic monitoring discrete element modelling stability analysis
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Prediction of Instability Separation Modes and Its Application in Practical Dynamic Security Region
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作者 曾沅 余贻鑫 +3 位作者 王红梅 闵亮 张沛 LEES T 《Transactions of Tianjin University》 EI CAS 2007年第3期157-162,共6页
The transient critical boundary of dynamic security region (DSR) can be approximated by a few hyper planes correlated with instability separation modes. A method to fast predict instability separation modes is propose... The transient critical boundary of dynamic security region (DSR) can be approximated by a few hyper planes correlated with instability separation modes. A method to fast predict instability separation modes is proposed for DSR calculation in power injection space. The method identifies coherent generation groups by the developed K-medoids algorithm, taking a similarity matrix derived from the reachability Grammian as the index. As an experimental result, reachability Grammian matrices under local injections are approximately invariant. It indicates that the generator coherency identifications are nearly consistent for different injections. Then instability separation modes can be predicted at the normal operating point, while average initial acceleration is considered as the measure of the critical generator group to amend the error. Moreover, based on these predicted instability separation modes, a critical point search strategy for DSR calculation is illustrated in the reduced injection space of the critical generators. The proposed method was evaluated using New England Test System, and the computation accuracy and speed in determining the practical DSR were improved. 展开更多
关键词 instability separation mode dynamic security region K-medoids algorithm reachability Grammian
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Facile fabrication of ZnIn2S4/SnS2 3D heterostructure for efficient visible-light photocatalytic reduction of Cr(Ⅵ) 被引量:4
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作者 Jingwen Pan Zhongjie Guan +1 位作者 Jianjun Yang Qiuye Li 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第1期200-208,共9页
Photocatalytic method has been intensively explored for Cr(VI)reduction owing to its efficient and environmentally friendly natures.In order to obtain a high efficiency in practical application,efficient photocatalyst... Photocatalytic method has been intensively explored for Cr(VI)reduction owing to its efficient and environmentally friendly natures.In order to obtain a high efficiency in practical application,efficient photocatalysts need to be developed.Here,ZnIn2S4/SnS2 with a three-dimensional(3D)heterostructure was prepared by a hydrothermal method and its photocatalytic performance in Cr(VI)reduction was investigated.When the mass ratio of SnS2 to ZnIn2S4 is 1:10,the ZnIn2S4/SnS2 composite exhibits the highest photocatalytic activity with 100%efficiency for Cr(VI)(50 mg/L)reduction within 70 min under visible-light irradiation,which is much higher than those of pure ZnIn2S4 and SnS2.The enhanced charge separation and the light absorption have been confirmed from the photoluminescence and UV-vis absorption spectra to be the two reasons for the increased activity towards photocatalytic Cr(VI)reduction.In addition,after three cycles of testing,no obvious degradation is observed with the 3D heterostructured ZnIn2S4/SnS2,which maintains a good photocatalytic stability. 展开更多
关键词 ZnIn2S4/SnS2 3D heterostructure Photocatalytic Cr(VI)reduction Visible-light response Charge separation Photocatalytic stability
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GPU-based discrete element simulation on flow stability of flat-bottomed hopper 被引量:1
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作者 Li Peng Zheng Zou +2 位作者 Libo Zhang Qingshan Zhu Hongzhong Li 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第1期43-52,共10页
In this study, the flow stability of the flat-bottomed hopper was investigated via GPU-based discrete element method(DEM) simulation. With the material height inside the hopper reducing, the fluctuation of the flow ra... In this study, the flow stability of the flat-bottomed hopper was investigated via GPU-based discrete element method(DEM) simulation. With the material height inside the hopper reducing, the fluctuation of the flow rate indicates an unstable discharge. The flow regions of the unstable discharge were compared with that of the stable discharge, a key transformation zone, where the voidage showed the largest difference between unstable and stable discharge, was revealed. To identify the relevance of the key transformation zone and the hopper flow stability, the voidage variation of the key transformation zone with material height reducing was studied.A sharp increase in the voidage in the key transformation zone was considered to be the standard for judging the unstable hopper flow, and the ‘Top–Bottom effect' of the hopper was defined, which indicated the hopper flow was unstable when the hopper only had the top area and the bottom area, because the voidage of particles in the top area and the bottom area were both variables. 展开更多
关键词 Stability Discrete element method(DEM) Granular flow Top-Bottom effect Flow regions
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Development of slope mass rating system using K-means and fuzzy c-means clustering algorithms 被引量:1
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作者 Jalali Zakaria 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2016年第6期959-966,共8页
Classification systems such as Slope Mass Rating(SMR) are currently being used to undertake slope stability analysis. In SMR classification system, data is allocated to certain classes based on linguistic and experien... Classification systems such as Slope Mass Rating(SMR) are currently being used to undertake slope stability analysis. In SMR classification system, data is allocated to certain classes based on linguistic and experience-based criteria. In order to eliminate linguistic criteria resulted from experience-based judgments and account for uncertainties in determining class boundaries developed by SMR system,the system classification results were corrected using two clustering algorithms, namely K-means and fuzzy c-means(FCM), for the ratings obtained via continuous and discrete functions. By applying clustering algorithms in SMR classification system, no in-advance experience-based judgment was made on the number of extracted classes in this system, and it was only after all steps of the clustering algorithms were accomplished that new classification scheme was proposed for SMR system under different failure modes based on the ratings obtained via continuous and discrete functions. The results of this study showed that, engineers can achieve more reliable and objective evaluations over slope stability by using SMR system based on the ratings calculated via continuous and discrete functions. 展开更多
关键词 SMR based on continuous functions Slope stability analysis K-means and FCM clustering algorithms Validation of clustering algorithms Sangan iron ore mines
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A New Car Following Model:Comprehensive Optimal Velocity Model 被引量:3
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作者 田钧方 贾斌 李新刚 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第6期1119-1126,共8页
In this paper, we present a new ear-following model, i.e. comprehensive optimal velocity model (COVM), whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also de... In this paper, we present a new ear-following model, i.e. comprehensive optimal velocity model (COVM), whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also depends on the velocity difference with preceding vehicle. Simulation results show that COVM is an improvement over the previous ones theoretically. Then, the stability condition of the model is obtained by the linear stability analysis, which has shown that the model could obtain a bigger stable region than previous models in the phase diagram. Through the nonlinear analysis, the Burgers, Korteweg-de Vries (KdV) and modified KdV (mKdV) equations are derived for the triangular shock wave, the soliton wave, and the kink-antikink soliton wave. At the same time, numerical simulations are also carried out to show that the model could simulate these density waves. 展开更多
关键词 car following traffic flow
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Speech Separation Based on Robust Independent Component Analysis 被引量:1
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作者 YAO Wen-po WU Min +2 位作者 LIU Tie-bing WANG Jun SHEN Qian 《Chinese Journal of Biomedical Engineering(English Edition)》 2013年第4期169-177,共9页
In this paper, we applied RobustICA to speech separation and made a comprehensive comparison to FastICA according to the separation results. Through a series of speech signal separation test, RobustICA reduced the sep... In this paper, we applied RobustICA to speech separation and made a comprehensive comparison to FastICA according to the separation results. Through a series of speech signal separation test, RobustICA reduced the separation time consumed by FastICA with higher stability, and speeches separated by RobustICA were proved to having lower separation errors. In the 14 groups of speech separation tests, separation time consumed by RobustICA was 3.185 s less than FastICA by nearly 68%. Separation errors of FastICA had a float between 0.004 and 0.02, while the errors of RobustlCA remained around 0.003. Furthermore, compared to FastICA, RobustlCA showed better separation robustness. Experimental results showed that RohustICA was successful to apply to the speech signal separation, and showed superiority to FastlCA in speech separation. 展开更多
关键词 RobustlCA speech separation FASTICA KURTOSIS optimal step size
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Purification and Stability of an Antithrombus Enzyme from Bacillus subtilis
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作者 关怡新 姚善泾 +1 位作者 俞丽华 梅乐和 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2004年第5期707-710,共4页
An antithrombus enzyme (ATE) was precipitated by (NH4)2SO4 or ethanol from supernatant of Bacillus subtilis culture broth then purified using ion exchange chromatography on CM-sepharose fast flow. The effects of ionic... An antithrombus enzyme (ATE) was precipitated by (NH4)2SO4 or ethanol from supernatant of Bacillus subtilis culture broth then purified using ion exchange chromatography on CM-sepharose fast flow. The effects of ionic strength and pH value on protein adsorption, the gradient elution at different flow rates and step elution were examined respectively. The recovery yield of the optimised process was 74.5% with a purification factor 8.1. The ATE molecular weight was estimated as 30ku by SDS-PAGE. The experimental results showed that the enzyme was stable in the range of pH 7 to pH11, and temperature 25℃ to 37℃. 展开更多
关键词 antithrombus enzyme PURIFICATION ion exchange chromatography ADSORPTION STABILITY
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基于Hammerstein模型的非线性分离法预测控制 被引量:3
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作者 李元明 潘红光 +1 位作者 邹涛 钱新华 《信息与控制》 CSCD 北大核心 2017年第2期172-177,共6页
采用非线性分离法综合了基于Hammerstein模型的稳定预测控制器.首先用有限时域稳定预测控制方法求解期望中间变量,然后求解非线性代数方程来反算实际控制作用.在求解期望中间变量时考虑输入非线性的不确定性和非线性代数方程的求解误差... 采用非线性分离法综合了基于Hammerstein模型的稳定预测控制器.首先用有限时域稳定预测控制方法求解期望中间变量,然后求解非线性代数方程来反算实际控制作用.在求解期望中间变量时考虑输入非线性的不确定性和非线性代数方程的求解误差.在确定有限时域优化问题的终端约束集和终端状态加权矩阵时,采用参数依赖方法并引入参考集以优化终端约束集.通过一个仿真例子验证了该控制算法. 展开更多
关键词 Hammerstein模型非线性分离法预测控制稳定性综合
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Controlling reduction degree of graphene oxide membranes for improved water permeance 被引量:9
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作者 Qing Zhang Xitang Qian +2 位作者 Khalid Hussain Thebo Hui-Ming Cheng Wencai Ren 《Science Bulletin》 SCIE EI CSCD 2018年第12期788-794,共7页
Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide (GO) and completely reduced GO (... Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide (GO) and completely reduced GO (rGO) membranes suffer florn low water permeance because of the lack of pristine graphitic sp2 domains and very small interlayer spacing, respectively. In this work, we studied the influence of reduction degree on the structure and separation pertornrance of rGO membranes, tt was found that weak reduction retains the good dispersion and hydrophilicity of GO nanosheets. More importantly, it increases the number of pristine graphitic sp2 domains in rGO nanosheets while keeping the large interlayer spacing of the GO membranes in most regions at the same time. The resultant mernbranes show a high water permeance of 56.3 L m^-2 h^ -1 bar^ -1, which is about 4 times and over 10^4 times larger tban those of the GO and completely reduced rGO membranes, respectively, and high rejection over 95700 for various dyes. Furthermore, they show better structure stability and more superior separation perfor- mance than GO membranes in acid and alkali environments. 展开更多
关键词 Graphene oxide Reduction Separation membrane Water permeance
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