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新拌水泥浆触变、反触变及其交错行为的解析 被引量:2
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作者 徐永模 黄大能 《上海建材学院学报》 CSCD 1990年第4期351-356,共6页
本文采用'台阶法循环'测试方法研究了新拌水泥浆的触变性和反触变性,发现不同的触变-反触变交错行为对应着不同的浆体结构状态.试验解析了各种循环曲线的产生过程,指出反触变行为不宜作为浆体的物性参数,因为它是剪切稠化作用所... 本文采用'台阶法循环'测试方法研究了新拌水泥浆的触变性和反触变性,发现不同的触变-反触变交错行为对应着不同的浆体结构状态.试验解析了各种循环曲线的产生过程,指出反触变行为不宜作为浆体的物性参数,因为它是剪切稠化作用所致,其大小决定于剪切强度和时间. 展开更多
关键词 水泥浆 变性 变性 台阶法
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数学概念在内涵与外延上的表征 被引量:1
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作者 唐虎 《大学数学》 1994年第4期273-279,共7页
本文提出并论述了数学概念在内涵与外延上的两个表征:(1)结层性;(2)侧综性。同时,还进一步阐明了数学概念的兼容性、非兼容性和反变性。
关键词 概念 内涵 外延 结层性 侧综性 兼容性 非兼容性 反变性
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炭粉对聚羧酸系减水剂与水泥相容性的影响
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作者 吴蓉 钱利姣 《粉煤灰综合利用》 CAS 2015年第2期10-14,共5页
以炭粉模拟研究聚羧酸系减水剂对与水泥相容性的影响,测定了炭粉对水泥净浆流动性能、流变性能及吸附性能的影响,同时提出了炭粉对聚羧酸系减水剂的吸附模型。结果表明:(1)当炭粉含量为3%时,掺聚羧酸系减水剂的水泥浆体相容性不良;(2)... 以炭粉模拟研究聚羧酸系减水剂对与水泥相容性的影响,测定了炭粉对水泥净浆流动性能、流变性能及吸附性能的影响,同时提出了炭粉对聚羧酸系减水剂的吸附模型。结果表明:(1)当炭粉含量为3%时,掺聚羧酸系减水剂的水泥浆体相容性不良;(2)炭粉可增大水泥净浆的粘度及屈服应力;(3)炭粉可使浆体由触变性立即转变为反触变性;(4)当减水剂平衡浓度≤3 g/L时,炭粉对减水剂的吸附为单分子层吸附,符合Langmuir吸附模型。 展开更多
关键词 聚羧酸系减水剂 炭粉 相容性问题 吸附模型 单分子层吸附 水泥熟料 净浆 吸附性能 变性 等温吸附曲线
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Theoretical Study of Antiferrodistortive Phase Transition in Strontium Titanate
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作者 蔡玉平 韩代朝 宁如云 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第2期237-240,I0002,共5页
At 105 K, strontium titanate is known to undergo an antiferrodistortive transition transform-ing from cubic to tetragonal structure as a result of the rotation of the oxygen octahedral around a cubic axe. Based on the... At 105 K, strontium titanate is known to undergo an antiferrodistortive transition transform-ing from cubic to tetragonal structure as a result of the rotation of the oxygen octahedral around a cubic axe. Based on the Curie principle, the order parameter is determined to be a third-order complete symmetry polarization tensor. To take into account of quantum effects,the dielectric permittivity is measured from Landau free energy, and the Curie Weiss-type behavior is analyzed. From crystallization chemistry viewpoint, the dielectric behavior at low temperature is connected to small radius of Sr^2+, which is much easier to move around the oxygen octahedral than Ba^2+ in BaTiO3 or Pb^2+ in PbTiO3. 展开更多
关键词 Spontaneous polarization Dielectric permittivity Free energy Antiferrodis-tortive phase transition
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Equilibrium Control Theory and Direct Method of Feedback Linearization for Nonlinear Time Varying Systems 被引量:1
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作者 王庆林 陈悦 《Journal of Beijing Institute of Technology》 EI CAS 1999年第3期306-311,共6页
Aim To present a simple and effective method for the design of nonlinear and time varying control system. Methods A new concept of dynamic equilibrium of a system and its stability were presented first. It was poin... Aim To present a simple and effective method for the design of nonlinear and time varying control system. Methods A new concept of dynamic equilibrium of a system and its stability were presented first. It was pointed out that what is controlled directly by the input of a control system is the system's dynamic equilibrium rather than the states. Based on it, a new feedback linearization method for nonlinear system based on the Lyapunov direct method was given. Simulation studies were also carried out. Results The example and simulation show that by use of the method, the controller design becomes very simple and the control effect is quite satisfying. Conclusion The new method unifies the stabilizing problem(regulating problem) with the tracking problem. It is a very simple and effective method for the design of nonlinear and time varying control system. 展开更多
关键词 dynamic equilibrium feedback linearization nonlinear system time varying system stability
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Studies on the relationship between the point mutation of ras oncogenes and the prognosis of patients with gastric cancer
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作者 房殿春 罗元辉 +1 位作者 鲁荣 刘为纹 《World Journal of Gastroenterology》 SCIE CAS CSCD 1997年第1期24+22-23,22-23,共3页
AIM To study the relationship between the point mutation of ras oncogenes and the prognosis of patients with gastric cancer.
关键词 Stomach neoplasms Genes ras Point mutation Polymerase chain reaction\ \ Polymorphism restriction fragment length Prognosis
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Airborne Pollen Grains Of Afyon, Turkey 被引量:3
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作者 Adem BICAKCI 1, Süheyla ERGUN 2, Sevcan TATLIDIL 1, Hulusi MALYER 1, Sabri ?ZYURT 2, Ahmet AKKAYA 3, Nihat SAPAN 5 Department of Biology, Faculty of Science, University of Uludag, Bursa, Turkey 2. Department of Biology, Faculty of Science, University of Afyon Kocatepe, Afyon Turkey +1 位作者 3. Department of Pulmonology, Faculty of Medicine, University of Süleyman Demirel, Isparta, Turkey 4. Division of Pediatric Allergy, Faculty of Medicine, University of Uludag, Bursa, Turkey) 《Acta Botanica Sinica》 CSCD 2002年第11期1371-1375,共5页
The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentif... The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of them, 6 732 were identified in 1999 and 7 635 in 2000. Of the total pollen grains, 69.67% were arboreal, 26.64% non_arboreal and 3.68 % unidentified. The majority of the investigated pollen grains were from Pinus, Gramineae, Cupressaceae, Platanus , Chenopodiaceae/Amaranthaceae, Quercus, Ailanthus, Moraceae, Juglans , Salix, Cedrus and Rosaceae. The highest level of pollen grains was in May. 展开更多
关键词 TURKEY Afyon pollen calendar pollen grains
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Linearization of T-S fuzzy systems and robust H_∞ control 被引量:4
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作者 YOON Tae-Sung 王法广 +2 位作者 PARK Seung-Kyu KWAK Gun-Pyong AHN Ho-Kyun 《Journal of Central South University》 SCIE EI CAS 2011年第1期140-145,共6页
Takagi-Sugeno(T-S) fuzzy model is difficult to be linearized because of membership functions included.So,novel T-S fuzzy state transformation and T-S fuzzy feedback are proposed for the linearization of T-S fuzzy syst... Takagi-Sugeno(T-S) fuzzy model is difficult to be linearized because of membership functions included.So,novel T-S fuzzy state transformation and T-S fuzzy feedback are proposed for the linearization of T-S fuzzy system.The novel T-S fuzzy state transformation is the fuzzy combination of local linear transformation which transforms local linear models in the T-S fuzzy model into the local linear controllable canonical models.The fuzzy combination of local linear controllable canonical model gives controllable canonical T-S fuzzy model and then nonlinear feedback is obtained easily.After the linearization of T-S fuzzy model,a robust H∞ controller with the robustness of sliding model control(SMC) is designed.As a result,controlled T-S fuzzy system shows the performance of H∞ control and the robustness of SMC. 展开更多
关键词 T-S fuzzy control LINEARIZATION H∞ control sliding mode control
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Novel measurement scheme of peak separation of side-hole fiber grating 被引量:1
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作者 LI Zhi-zhong SUN Chong-feng CAO Chun-yan YANG Hua-yong HU Yong-ming 《Optoelectronics Letters》 EI 2006年第2期109-111,共3页
There are two peaks of different polarizations in the reflection spectrum of the side-hole fiber grating and their separation interval has a linear variation along with the pressure changing while it is insensitive to... There are two peaks of different polarizations in the reflection spectrum of the side-hole fiber grating and their separation interval has a linear variation along with the pressure changing while it is insensitive to the temperature.We have proposed a novel measurement scheme based on polarization detection.The detection of peak separation is achieved by measuring the two peaks’ center wavelengths separately with all polarization maintaining fiber system.The side-hole fiber grating pressure sensing within the range of 0~3.5 MPa is realized successfully with the new scheme. 展开更多
关键词 光纤光栅 偏振现象 射光谱 线性变异 波长
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Effect of Operation Variables on Hydrodenitrogenation and Hydrodesulfurization over NiMo/Al_2O_3 Catalysts 被引量:2
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作者 段爱军 徐春明 林世雄 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2003年第6期743-746,共4页
Using the JQ-II high pressure hydrogenation micro-reactor unit, the reactivity of Athabasca bitumen derived heavy gas oil was studied over commercial and homemade hydrotreating catalysts. The effects of catalyst prepa... Using the JQ-II high pressure hydrogenation micro-reactor unit, the reactivity of Athabasca bitumen derived heavy gas oil was studied over commercial and homemade hydrotreating catalysts. The effects of catalyst preparation variables and the influences of operation conditions, such as pressure, temperature, hydrogen/oil ratio and space velocity were also examined. It was shown that the optimal concentrations of the active components were 5% of NiO, 20% of MoO3 and 3.5% of phosphorus (by mass), and the suitable operation conditions were determined experimentally. 展开更多
关键词 HYDROTREATMENT heavy gas oil HYDRODESULFURIZATION HYDRODENITROGENATION
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Elastodynamic modeling and joint reaction prediction for 3-PRS PKM 被引量:4
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作者 张俊 赵艳芹 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第8期2971-2979,共9页
To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used a... To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used as a case study to illustrate the process of joint reaction analysis. The substructure synthesis method is applied to deriving an analytical elastodynamic model for the 3-PRS PKM device, in which the compliances of limbs and joints are considered. Each limb assembly is modeled as a spatial beam with non-uniform cross-section supported by lumped virtual springs at the centers of revolute and spherical joints. By introducing the deformation compatibility conditions between the limbs and the platform, the governing equations of motion of the system are obtained. After degenerating the governing equations into quasi-static equations, the effects of the gravity on system deflections and joint reactions are investigated with the purpose of providing useful information for the kinematic calibration and component strength calculations as well as structural optimizations of the 3-PRS PKM module. The simulation results indicate that the elastic deformation of the moving platform in the direction of gravity caused by gravity is quite large and cannot be ignored. Meanwhile, the distributions of joint reactions are axisymmetric and position-dependent. It is worthy to note that the proposed elastodynamic modeling method combines the benefits of accuracy of finite element method and concision of analytical method so that it can be used to predict the stiffness characteristics and joint reactions of a PKM throughout its entire workspace in a quick and accurate manner. Moreover, the present model can also be easily applied to evaluating the overall rigidity performance as well as statics of other PKMs with high efficiency after minor modifications. 展开更多
关键词 parallelkinematic machine (PKM) 3-PRS PKM Sprint Z3 head elastodynamic modeling joint reaction
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Measurement and analysis of soil nitrogen and organic matter content using near-infrared spectroscopy techniques 被引量:8
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作者 何勇 宋海燕 +1 位作者 PEREIRA Annia García GóMEZ Antihus Hernández 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE EI CAS CSCD 2005年第11期1081-1086,共6页
Near infrared reflectance (N1R) spectroscopy is as a rapid, convenient and simple nondestructive technique useful for quantifying several soil properties. This method was used to estimate nitrogen (N) and organic ... Near infrared reflectance (N1R) spectroscopy is as a rapid, convenient and simple nondestructive technique useful for quantifying several soil properties. This method was used to estimate nitrogen (N) and organic matter (OM) content in a soil of Zhejiang Province, Hangzhou County. A total of 125 soil samples were taken from the field. Ninety-five samples spectra were used during the calibration and cross validation stage. Thirty samples spectra were used to predict N and OM concentration. NIR spectra of these samples were correlated using partial least square regression. The regression coefficients between measured and predicted values of N and OM was 0.92 and 0.93, and SEP (standard error of prediction) were 3.28 and 0.06, respectively, which showed that NIR method had potential to accurately predict these constituents in this soil. The results showed that NIR spectroscopy could be a good tool for precision farming application. 展开更多
关键词 NIR spectroscopy Partial least square Precision farming Soil spatial variability NITROGEN Organic matter
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The Seasonal Variations of Aerosols over East Asia as Jointly Inferred from MODIS and OMI 被引量:5
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作者 LIU Qi DING Wei-Dong FU Yun-Fei 《Atmospheric and Oceanic Science Letters》 2011年第6期330-337,共8页
Data on aerosol optical thickness(AOT) and single scattering albedo(SSA) derived from Moderate Resolution Imaging Spectrometer(MODIS) and Ozone Monitoring Instrument(OMI) measurements,respectively,are used jointly to ... Data on aerosol optical thickness(AOT) and single scattering albedo(SSA) derived from Moderate Resolution Imaging Spectrometer(MODIS) and Ozone Monitoring Instrument(OMI) measurements,respectively,are used jointly to examine the seasonal variations of aerosols over East Asia.The seasonal signals of the total AOT are well defined and nearly similar over the land and over the ocean.These findings indicate a natural cycle of aerosols that originate primarily from natural emissions. In contrast,the small-sized aerosols represented by the fine-mode AOT,which are primarily generated over the land by human activities,do not have evident seasonalscale fluctuations.A persistent maximum of aerosol loadings centered over the Sichuan basin is associated with considerable amounts of fine-mode aerosols throughout the year.Most regions exhibit a general spring maximum. During the summer,however,the aerosol loadings are the most marked over north central China.This occurrence may result from anthropogenic fine particles,such as sulfate and nitrate.Four typical regions were selected to perform a covariation analysis of the monthly gridded AOT and SSA.Over southwestern and southeastern China,if the aerosol loadings are small to moderate they are composed primarily of the highly absorptive aerosols. However,more substantial aerosol loadings probably represent less-absorptive aerosols.The opposite covariation pattern occurring over the coastal-adjacent oceans suggests that the polluted oceanic atmosphere is closely correlated with the windward terrestrial aerosols.North central China is strongly affected by dust aerosols that show moderate absorption.This finding may explain the lower variability in the SSA that accompanies increasing aerosol loadings in this region. 展开更多
关键词 aerosol optical thickness single scattering albedo seasonal variation Moderate Resolution Imaging Spectrometer Ozone Monitoring Instrument
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Sign-invariant and Explicit Solutions of Nonlinear Reaction-Diffusion Systems 被引量:1
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作者 ZHU Xiao-Ning ZHANG Shun-Li 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第6期1361-1364,共4页
Using the sign-invariant theory, we study the nonlinear reaction-diffusion systems. We also obtain some new explicit solutions to the nonlinear resulting systems.
关键词 sign-invariant theory nonlinear reaction-diffusion system explicit solutions
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Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation 被引量:2
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作者 祖子清 穆穆 Henk A.DIJKSTRA 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2013年第6期1356-1362,共7页
Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation(THC) is investigated with a three-dimensional ocean circulation model,using the conditional nonlinear optimal perturbation metho... Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation(THC) is investigated with a three-dimensional ocean circulation model,using the conditional nonlinear optimal perturbation method.The results show two types of optimal initial perturbations of sea surface salinity,one associated with freshwater and the other with salinity.Both types of perturbations excite decadal variability of the THC.Under the same amplitude of initial perturbation,the decadal variation induced by the freshwater perturbation is much stronger than that by the salinity perturbation,suggesting that the THC is more sensitive to freshwater than salinity perturbation.As the amplitude of initial perturbation increases,the decadal variations become stronger for both perturbations.For salinity perturbations,recovery time of the THC to return to steady state gradually saturates with increasing amplitude,whereas this recovery time increases remarkably for freshwater perturbations.A nonlinear(advective) feedback between density and velocity anomalies is proposed to explain these characteristics of decadal variability excitation.The results are consistent with previous ones from simple box models,and highlight the importance of nonlinear feedback in decadal THC variability. 展开更多
关键词 thermohaline circulation decadal variability conditional nonlinear optimal perturbation nonlinear advective feedback
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A Study on the Dynamic Performance of Hydroviscous Driyes 被引量:3
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作者 蔡笃景 魏宸官 《Journal of Beijing Institute of Technology》 EI CAS 1992年第2期111-121,共11页
Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of... Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of this device is studied according to the model.Theoretical analysis and test re- suits show that the dynamic performance of the object of study can be greatly improved by speed negative feedback. 展开更多
关键词 Speed control system speed changing devices non-linear control systems feedback compensation/hydroviscous drive oil film shear clutch
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Response of North Pacific and North Atlantic decadal variability to weak global warming 被引量:5
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作者 WU Sheng LIU Zheng-Yu +1 位作者 CHENG Jun LI Chun 《Advances in Climate Change Research》 SCIE CSCD 2018年第2期95-101,共7页
The Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Variability (AMV) are the two dominant low-frequency modes in the climate system. This research focused on the response of these two modes under ... The Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Variability (AMV) are the two dominant low-frequency modes in the climate system. This research focused on the response of these two modes under weak global warming. Observational data were derived from the Hadley Center Sea Ice and Sea Surface Temperature dataset (HadISST) and coupled model outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Changes in PDO and AMV were examined using four models (bcc-csml-1, CCSM4, IPSL-CM5A-LR, and MPI- ESM-LR) with long weak global warming scenarios (RCP2.6). These models captured the two low-frequency modes in both pre-industrial run and RCP2.6 run. Under weak global warming, the time scales of PDO and AMV significantly decreased while the amplitude only slightly decreased. Interestingly, the standard deviation of the North Pacific sea surface temperature anomaly (SSTA) decreased only in decadal time scale, and that of the North Atlantic SSTA decreased both in interannual and decadal time scales. The coupled system consists of a slow ocean component, which has a decadal time scale, and a fast atmospheric component, which is calculated by subtracting the decadal from the total. Results suggest that under global warming, PDO change is dominated by ocean dynamics, and AMV change is dominated by ocean dynamics and stochastic atmosphere forcing. 展开更多
关键词 Pacific decadal oscillation Atlantic multidecadal variability RCP2.6
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Effect of Lattice Distortion on Charge Order in Manganites at Doping x=0.5 被引量:1
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作者 WANGHai-Long TIANGuang-Shan LINHai-Qing 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第1期179-186,共8页
In the present paper, we continue our investigation on the antiferromagneticorigin of the charge order observed in the halt-doped manganese. By introducing aSu-Schrieffer-Heeger (SSH) type of perturbation interaction ... In the present paper, we continue our investigation on the antiferromagneticorigin of the charge order observed in the halt-doped manganese. By introducing aSu-Schrieffer-Heeger (SSH) type of perturbation interaction to the double-exchange Hamiltonian, wecalculate again its ground-state phase diagram at Glling x = 0.5 by the unrestricted real-spaceHartree-Fock approximation method. We find that, as the SSH electron-phonon interaction increases,the charge order parameter decreases to zero rapidly but the CE-type antiferromagnetic order becomesmore stable. In other words, the charge order is much more fragile than the CE-type or theNeel-type antiferromagnetic orders under the electron-phonon perturbation. These results support theproposed theory in the recent publications that the charge order in these systems is induced by theantiferromagnetic correlations. 展开更多
关键词 MANGANITES charge ordered phases antiferromagnetic correlation
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Variable step-size affine projection algorithm based on global speech absence probability for adaptive feedback cancellation 被引量:3
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作者 KIM Young-Sear SONG Ji-hyun +1 位作者 KIM Sang-Kyun LEE Sangmin 《Journal of Central South University》 SCIE EI CAS 2014年第2期646-650,共5页
A novel approach is proposed for improving adaptive feedback cancellation using a variable step-size affine projection algorithm(VSS-APA) based on global speech absence probability(GSAP).The variable step-size of the ... A novel approach is proposed for improving adaptive feedback cancellation using a variable step-size affine projection algorithm(VSS-APA) based on global speech absence probability(GSAP).The variable step-size of the proposed VSS-APA is adjusted according to the GSAP of the current frame.The weight vector of the adaptive filter is updated by the probability of the speech absence.The performance measure of acoustic feedback cancellation is evaluated using normalized misalignment.Experimental results demonstrate that the proposed approach has better performance than the normalized least mean square(NLMS) and the constant step-size affine projection algorithms. 展开更多
关键词 adaptive feedback cancellation affine projection global speech absence probability(GSAP)
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Effect of heat treatment on structure and gasification reactivity of petroleum coke 被引量:9
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作者 Chao Li Xin Liu +3 位作者 Zhijie Zhou Zhenghua Dai Ji Yan Fuchen Wang 《International Journal of Coal Science & Technology》 EI 2016年第1期53-61,共9页
Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as ... Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173-1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as the gasification reactivity of the heat-treated petroleum cokes were investigated. The results showed that the petroleum coke was carbonized and grapbitized to a higher degree with increasing heating temperature, while the gasification reactivity decreased. The treatment at temperatures of 1173 and 1473 K significantly enlarged the specific surface area and the pore volume of petroleum coke. Both the specific surface area and the pore volume decreased at 1673 K. An empirical normal distribution function model (NDFM) was found to fit the gasification rates of petroleum coke well. The correlation coefficient of petroleum coke by normal distribution function model at different heat treatment temperatures is between 0.93 and 0.95. 展开更多
关键词 Petroleum coke Heat treatment Gasification reactivity GRAPHITIZATION
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