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What Does a First Order Model Tell Us about PEEP Wave Maneuvers?
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作者 B.Laufer J.Kretschmer +2 位作者 P.D.Docherty Y.S.Chiew K.Moller 《Journal of Biomedical Science and Engineering》 2017年第5期66-75,共10页
Patients with acute respiratory distress syndrome (ARDS) are currently treated with a lung protective ventilation strategy and the application of positive end-expiratory pressure (PEEP), sometimes in combination with ... Patients with acute respiratory distress syndrome (ARDS) are currently treated with a lung protective ventilation strategy and the application of positive end-expiratory pressure (PEEP), sometimes in combination with recruitment maneuvers. In this study, the respiratory system elastance and airway resistance of each breath before, during and after a specific recruitment maneuver (PEEP wave maneuver) were analyzed in two patient groups, ARDS and control group. A reduction of elastance after the maneuver was observed in ARDS patients. In addition, only healthy lungs exhibited a reduction of the elastance during the course of the maneuver, while the lungs of ARDS patients didn’t show that reduction of elastance. The capability of PEEP wave maneuvers to improve lung ventilation was shown and the dynamic behavior of the elastance after the maneuver was illustrated. Healthy lungs adapt faster to changes in mechanical ventilation than the lungs of ARDS patients. 展开更多
关键词 ARDS Positive End-Expiratory Pressure Recruitment Maneuvers first order model Lung Mechanics
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Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials
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作者 LI Fan ZHAO Jian-hui 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2007年第2期157-161,共5页
Preisach model is widely used in modeling of smart materials. Although first order reversal curves (FORCs) have often found applications in the fields of physics and geology, they are able to serve to identify Preis... Preisach model is widely used in modeling of smart materials. Although first order reversal curves (FORCs) have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards: (1) giving the reason a first order reversal curve is introduced; (2) presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution's uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to. 展开更多
关键词 first order reversal curve Preisach model smart material DISCRETE IDENTIFY
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MATHEMATICAL MODEL FOR THERMOKINETICS OF IRREVERSIBLE CONSECUTIVE FIRST ORDER REACTIONS
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作者 Jing Song LIU Xian Cheng ZENG Yu DENG An Min TIAN Department of Chemistry,Sichuan University,Chengdu 610064 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第9期801-804,共4页
The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps... The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps.And its validity has been verified by the ex- perimental results. 展开更多
关键词 MATHEMATICAL model FOR THERMOKINETICS OF IRREVERSIBLE CONSECUTIVE first order REACTIONS ETOH
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Estimation of Landfill Gas and Its Renewable Energy Potential from the Polesgo Controlled Landfill Using First-Order Decay (FOD) Models
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作者 Haro Kayaba Ouarma Issoufou +4 位作者 Dabilgou Téré Compaore Abdoulaye Sanogo Oumar Bere Antoine Koulidiati Jean 《Journal of Environmental Protection》 2024年第10期975-993,共19页
Methane generation in landfills and its inadequate management represent the major avoidable source of anthropogenic methane today. This paper models methane production and the potential resources expected (electrical ... Methane generation in landfills and its inadequate management represent the major avoidable source of anthropogenic methane today. This paper models methane production and the potential resources expected (electrical energy production and potential carbon credits from avoided CH4 emissions) from its proper management in a municipal solid waste landfill located in Ouagadougou, Burkina Faso. The modeling was carried out using two first-order decay (FOD) models (LandGEM V3.02 and SWANA) using parameters evaluated on the basis of the characteristics of the waste admitted to the landfill and weather data for the site. At the same time, production data have been collected since 2016 in order to compare them with the model results. The results obtained from these models were compared to experimental one. For the simulation of methane production, the SWANA model showed better consistency with experimental data, with a coefficient of determination (R²) of 0.59 compared with the LandGEM model, which obtained a coefficient of 0.006. Thus, despite the low correlation values linked to the poor consistency of experimental data, the SWANA model models methane production much better than the LandGEM model. Thus, despite the low correlation values linked to the poor consistency of the experimental data, the SWANA model models methane production much better than the LandGEM V3.02 model. It was noted that the poor consistency of the experimental data justifies these low coefficients, and that they can be improved in the future thanks to ongoing in situ measurements. According to the SWANA model prediction, in 27 years of operation a biogas plant with 33% electrical efficiency using biogas from the Polesgo landfill would avoid 1,340 GgCO2e. Also, the evaluation of revenues due to electricity and carbon credit gave a total revenue derived from methane production of US$27.38 million at a cost of US$10.5/tonne CO2e. 展开更多
关键词 first-order Decay METHANE modeling LANDFILL Renewable Energy
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Illustrative Application of the 2<sup>nd</sup>-Order Adjoint Sensitivity Analysis Methodology to a Paradigm Linear Evolution/Transmission Model: Point-Detector Response 被引量:2
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作者 Dan Gabriel Cacuci 《American Journal of Computational Mathematics》 2020年第3期355-381,共27页
This work illustrates the application of the “Second Order Comprehensive Adjoint Sensitivity Analysis Methodology” (2<sup>nd</sup>-CASAM) to a mathematical model that can simulate the evolution and/or tr... This work illustrates the application of the “Second Order Comprehensive Adjoint Sensitivity Analysis Methodology” (2<sup>nd</sup>-CASAM) to a mathematical model that can simulate the evolution and/or transmission of particles in a heterogeneous medium. The model response is the value of the model’s state function (particle concentration or particle flux) at a point in phase-space, which would simulate a pointwise measurement of the respective state function. This paradigm model admits exact closed-form expressions for all of the 1<sup>st</sup>- and 2<sup>nd</sup>-order response sensitivities to the model’s uncertain parameters and domain boundaries. These closed-form expressions can be used to verify the numerical results of production and/or commercial software, e.g., particle transport codes. Furthermore, this paradigm model comprises many uncertain parameters which have relative sensitivities of identical magnitudes. Therefore, this paradigm model could serve as a stringent benchmark for inter-comparing the performances of all deterministic and statistical sensitivity analysis methods, including the 2<sup>nd</sup>-CASAM. 展开更多
关键词 Second-order Adjoint Comprehensive Sensitivity Analysis Methodology (2nd-CASAM) Evolution Benchmark model Exact and Efficient Computation of first- and Second-order Response Sensitivities
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Illustrative Application of the 2<sup>nd</sup>-Order Adjoint Sensitivity Analysis Methodology to a Paradigm Linear Evolution/Transmission Model: Reaction-Rate Detector Response 被引量:2
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作者 Dan Gabriel Cacuci 《American Journal of Computational Mathematics》 2020年第3期382-397,共16页
This work continues the illustrative application of the “Second Order Comprehensive Adjoint Sensitivity Analysis Methodology” (2<sup>nd</sup>-CASAM) to a benchmark mathematical model that can simulate th... This work continues the illustrative application of the “Second Order Comprehensive Adjoint Sensitivity Analysis Methodology” (2<sup>nd</sup>-CASAM) to a benchmark mathematical model that can simulate the evolution and/or transmission of particles in a heterogeneous medium. The model response considered in this work is a reaction-rate detector response, which provides the average interactions of particles with the respective detector or, alternatively, the time-average of the concentration of a mixture of substances in a medium. The definition of this model response includes both uncertain boundary points of the benchmark, thereby providing both direct and indirect contributions to the response sensitivities stemming from the boundaries. The exact expressions for the 1<sup>st</sup>- and 2<sup>nd</sup>-order response sensitivities to the boundary and model parameters obtained in this work can serve as stringent benchmarks for inter-comparing the performances of all (deterministic and statistical) sensitivity analysis methods. 展开更多
关键词 Second-order Adjoint Comprehensive Sensitivity Analysis Methodology (2nd-CASAM) Evolution Benchmark model Exact and Efficient Computation of first- and Second-order Response Sensitivities
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结合扩展卡尔曼滤波的GNSS/IMU组合定位误差建模
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作者 顾杰 《测绘与空间地理信息》 2026年第1期156-159,163,共5页
为解决GNSS/IMU组合定位在控制测量中的精度与鲁棒性问题,构建IMU确定性与随机性误差分层建模体系。确定性误差用分段多项式刻画零偏时变并修正安装误差;随机性误差以一阶高斯-马尔可夫(GM)模型结合Allan方差定参。融合策略采用紧耦合... 为解决GNSS/IMU组合定位在控制测量中的精度与鲁棒性问题,构建IMU确定性与随机性误差分层建模体系。确定性误差用分段多项式刻画零偏时变并修正安装误差;随机性误差以一阶高斯-马尔可夫(GM)模型结合Allan方差定参。融合策略采用紧耦合扩展卡尔曼滤波(EKF),设计多维度状态向量直接融合GNSS原始伪距来减小中间误差,引入新息协方差自适应机制调整噪声矩阵避免滤波发散。实验显示,各项指标可满足控制测量野外作业需求。 展开更多
关键词 控制测量 GNSS/IMU组合定位 紧耦合扩展卡尔曼滤波 一阶GM模型 自适应融合
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A New Lung Mechanics Model and Its Evaluation with Clinical Data
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作者 Manjunath Jayaramaiah Bernhard Laufer +1 位作者 Jörn Kretschmer Knut Möller 《Journal of Biomedical Science and Engineering》 2016年第10期107-115,共9页
Acute Respiratory Distress Syndrome (ARDS) is a major cause of morbidity and has a high rate of mortality. ARDS patients in the intensive care unit (ICU) require mechan-ical ventilation (MV) for breathing support, but... Acute Respiratory Distress Syndrome (ARDS) is a major cause of morbidity and has a high rate of mortality. ARDS patients in the intensive care unit (ICU) require mechan-ical ventilation (MV) for breathing support, but inappropriate settings of MV can lead to ventilator induced lung injury (VILI). Those complications may be avoided by carefully optimizing ventilation parameters through model-based approaches. In this study we introduced a new model of lung mechanics (mNARX) which is a variation of the NARX model by Langdon et al. A multivariate process was undertaken to deter-mine the optimal parameters of the mNARX model and hence, the final structure of the model fit 25 patient data sets and successfully described all parts of the breathing cycle. The model was highly successful in predicting missing data and showed minimal error. Thus, this model can be used by the clinicians to find the optimal patient specific ventilator settings. 展开更多
关键词 Acute Respiratory Distress Syndrome Ventilator Induced Lung Injury Non-Linear Autoregressive model first order model Mechanical Ventilation
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On the Parameterization of Convective Entrainment: Inherent Relationships among Entrainment Parameters in Bulk Models 被引量:2
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作者 孙鉴泞 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2009年第5期1005-1014,共10页
In this paper, the equilibrium entrainment into a shear-free, linearly stratified atmosphere is discussed under the framework of bulk models, namely, the zero-order jump model (ZOM) and the first-order jump model (... In this paper, the equilibrium entrainment into a shear-free, linearly stratified atmosphere is discussed under the framework of bulk models, namely, the zero-order jump model (ZOM) and the first-order jump model (FOM). The parameterizations for the dimensionless entrainment rate versus the convective Richard- son number in the two models are compared. Based on the assumption that the parameterized entrainment rates in ZOM and FOM should be the same, the inherent relationships among the entrainment parameters in the bulk models are revealed. These relationships are supported by tank experiments and large-eddy sim- ulations. The validity of these inherent relationships indicates that, for a convective boundary layer growing into a linearly stratified free atmosphere, the only dominant factors of the growth rate are the turbulent buoyancy in the mixed layer and the stratification in the free atmosphere. In the point of the similarity view, the former is characterized by turbulent temperature and mixing length scales (mixed layer depth), and the latter is characterized by the lapse rate of potential temperature in the free atmosphere. Thus, the commonly-used Richardson number scheme for the parameterization of the entrainment rate is just as an equivalent description. The variability of the total entrainment flux ratio in FOM, which is connected with the entrainment zone thickness, can implicitly describe the effect of the stratification in the free atmosphere, but the entrainment zone thickness is not an independent parameter. These results demonstrate the validity of the hypothesis that there exists a similarity limit in which the mixed layer depth is the only lengthscale. 展开更多
关键词 zero-order jump model first-order jump model convective Richardson number entrainmentrate lengthscale
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Fractional-order Generalized Principle of Self-support (FOGPSS) in Control System Design
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作者 Hua Chen YangQuan Chen 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI 2016年第4期430-441,共12页
This paper reviews research that studies the principle of self-support U+0028 PSS U+0029 in some control systems and proposes a fractional-order generalized PSS framework for the first time. The existing PSS approach ... This paper reviews research that studies the principle of self-support U+0028 PSS U+0029 in some control systems and proposes a fractional-order generalized PSS framework for the first time. The existing PSS approach focuses on practical tracking problem of integer-order systems including robotic dynamics, high precision linear motor system, multi-axis high precision positioning system with unmeasurable variables, imprecise sensor information, uncertain parameters and external disturbances. More generally, by formulating the fractional PSS concept as a new generalized framework, we will focus on the possible fields of the fractional-order control problems such as practical tracking, U+03BB-tracking, etc. of robot systems, multiple mobile agents, discrete dynamical systems, time delay systems and other uncertain nonlinear systems. Finally, the practical tracking of a first-order uncertain model of automobile is considered as a simple example to demonstrate the efficiency of the fractional-order generalized principle of self-support U+0028 FOGPSS U+0029 control strategy. © 2014 Chinese Association of Automation. 展开更多
关键词 Control systems Delay control systems Dynamical systems Linear motors Mobile agents ROBOTICS Time delay Uncertainty analysis
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EXTENSION OF CONVEX MODELS AND ITS IMPROVEMENT ON THE APPROXIMATE SOLUTION 被引量:3
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作者 邱志平 顾元宪 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1996年第4期349-357,共9页
In this paper, by means of combining non-probabilistic convex modeling with perturbation theory, an improvement is made on the first order approximate solution in convex models of uncertainties. Convex modeling is ext... In this paper, by means of combining non-probabilistic convex modeling with perturbation theory, an improvement is made on the first order approximate solution in convex models of uncertainties. Convex modeling is extended to largely uncertain and non-convex sets of uncertainties and the combinational convex modeling is developed. The presented method not only extends applications of convex modeling, but also improves its accuracy in uncertain problems and computational efficiency. The numerical example illustrates the efficiency of the proposed method. 展开更多
关键词 convex modeling uncertain but bounded parameters NONCONVEXITY PERTURBATION first order approximation
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Microcanonical Monte Carlo Simulation of 2D 4-State Potts Model
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作者 Snehadri Bihari Ota Smita Ota Akiro Ota 《Journal of Modern Physics》 2017年第4期602-606,共5页
Monte Carlo simulation of two dimensional 4 state Potts model has been carried out in microcanonical ensemble. The simulations were done on a 30 × 30 system with periodic boundary conditions. The temperature depe... Monte Carlo simulation of two dimensional 4 state Potts model has been carried out in microcanonical ensemble. The simulations were done on a 30 × 30 system with periodic boundary conditions. The temperature dependence of energy and order parameter has been calculated. The transition in 4-state Potts model is concluded to be first-order in nature. The transition temperature and latent heat of the first-order transition have been found to be 0.92 and 0.18, respectively. 展开更多
关键词 MICROCANONICAL MONTE Carlo POTTS model first-order TRANSITION
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Method of a New Iteration Scheme Combined with Kriging Model for Structural Reliability Evaluation
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作者 杨杰 黄一 +1 位作者 张崎 赵德有 《Journal of Shanghai Jiaotong university(Science)》 EI 2012年第4期415-420,共6页
The first order reliability method (FORM) is widely adopted for structural reliability evaluation due to its numerical efficiency. Concerning the issue of FORM often failing to converge when the limit state function (... The first order reliability method (FORM) is widely adopted for structural reliability evaluation due to its numerical efficiency. Concerning the issue of FORM often failing to converge when the limit state function (LSF) behaves high nonlinearity, a new iteration scheme called "rotated gradient algorithm (RGA)" is proposed and combined with Kriging model to evaluate the reliability of implicit performance function. In this paper, the Kriging model is applied to approximate the real LSF first. Then the scheme of RGA, constructed in terms of gradient information of two adjacent design points obtained during the process of calculation, is used to calculate the reliability index. Numerical examples show the validity in convergence and accuracy of the proposed methodfor arbitrary nonlinear performance function. 展开更多
关键词 reliability analysis Kriging model first order reliability method (FORM) iteration scheme
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Current Model Analysis of South China Sea Based on Empirical Orthogonal Function(EOF) Decomposition and Prototype Monitoring Data 被引量:4
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作者 WU Wenhua LIU Ming +1 位作者 YU Siyuan WANG Yanlin 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第2期305-316,共12页
Environmental load is the primary factor in the design of offshore engineering structures and ocean current is the principal environmental load that causes underwater structural failure. In computational analysis, the... Environmental load is the primary factor in the design of offshore engineering structures and ocean current is the principal environmental load that causes underwater structural failure. In computational analysis, the calculation of current load is mainly based on the current profile. The current profile model, which is based on a structural failure criterion, is conducive to decreasing the uncertainty of the current load. In this study, we used prototype monitoring data and the empirical orthogonal function(EOF) method to investigate the current profile in the South China Sea and its correlation with the design of underwater structural strength and the dynamic design of fatigue. The underwater structural strength design takes into account the size of the structure and the service water depth. We propose profiles for the overall and local designs using the inverse first-order reliability method(IFORM). We extracted the characteristic profile current(CPC) of the monitored sea area to solve dynamic design problems such as vortex-induced vibration(VIV). We used random sampling to verify the feasibility of using the EOF method to calculate the CPC from the current data and identified the main problems associated with using the CPC, which deserve close attention in VIV design. Our research conclusions provide direct references for determining current load in this sea area. This analysis method can also be used in the analysis of other sea areas or field variables. 展开更多
关键词 CURRENT PROFILE model failure criteria PROTOTYPE monitoring inverse first-order reliability method(IFORM) Characteristic PROFILE current(CPC)
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大语言模型工具能促进高校学生的高阶思维能力发展吗?——基于12所双一流大学学生问卷调查的实证分析 被引量:7
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作者 李曼丽 乔伟峰 李睿淼 《现代教育技术》 2025年第1期34-43,共10页
在数智时代,重视培养高校学生的高阶思维能力已逐渐成为共识,但高校学生使用大语言模型工具能否促进高阶思维能力的发展尚存争议。澄清这一争议,不仅有助于在理论上分析人工智能背景下学生高阶思维发展的机理,也可以为学校和教师在教育... 在数智时代,重视培养高校学生的高阶思维能力已逐渐成为共识,但高校学生使用大语言模型工具能否促进高阶思维能力的发展尚存争议。澄清这一争议,不仅有助于在理论上分析人工智能背景下学生高阶思维发展的机理,也可以为学校和教师在教育实践中采取何种措施提供可靠依据。基于此,文章利用我国12所双一流大学学生的问卷调查数据,对当前高校学生的大语言模型工具使用情况及其对高阶思维能力的影响进行实证分析,结果显示:超过半数的高校学生使用过大语言模型工具,但深度创意应用仍有待加强;增加大语言模型工具的基础执行应用与深度创意应用频次,均对高阶思维能力发展具有显著的正向影响;交互质量在大语言模型工具使用频次对高阶思维能力的影响过程中发挥中介作用。在此基础上,文章建议高校正视人工智能技术在高等教育教学过程中的作用,积极推动人工智能赋能教育应用;结合课内外真实情境,促进大语言模型工具的深度创意应用;加强师生人工智能素养培养,提升人机交互质量。 展开更多
关键词 大语言模型 高阶思维能力 高校学生 双一流大学
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遥感时空知识图谱驱动的自然资源要素变化图斑智能净化 被引量:3
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作者 李彦胜 钟振宇 +5 位作者 孟庆祥 毛之典 党博 王涛 冯苑君 张永军 《地球信息科学学报》 北大核心 2025年第2期350-366,共17页
【目的】随着深度学习技术的发展,遥感影像自然资源要素变化监测能力得到显著提高。基于深度学习的变化检测技术善于挖掘遥感影像的低层次语义信息,但在区分土地利用类型变化与非土地利用类型变化(如农作物轮作、水位自然变化、森林自... 【目的】随着深度学习技术的发展,遥感影像自然资源要素变化监测能力得到显著提高。基于深度学习的变化检测技术善于挖掘遥感影像的低层次语义信息,但在区分土地利用类型变化与非土地利用类型变化(如农作物轮作、水位自然变化、森林自然退化等)方面存在局限性。为了保证变化检测的高召回率,深度学习变化检测方法往往产生大量虚警变化图斑,仍需大量人工作业工作量来排除虚警变化图斑。【方法】针对这一问题,本文提出了遥感时空知识图谱驱动的自然资源要素变化图斑净化算法。该方法可以在保持变化图斑高召回率的前提下,尽可能降低变化图斑虚警率,从而提高自然资源要素变化监测效率。为了支撑遥感时空知识图谱智能构建与高效推理,本文设计了顾及时空特性的遥感时空知识图谱本体模式,研发了图数据库内存储运算一体化的GraphGIS工具包。本文提出了基于GraphGIS图数据库原生空间分析的矢量知识抽取技术、基于SkySense视觉大模型高效微调的遥感影像知识抽取技术和基于SeqGPT大语言模型的图斑净化知识抽取技术。在时空本体模式约束下,矢量知识、影像知识和文本知识汇聚形成遥感时空知识图谱。受变化图斑净化业务人工作业方式的启发,本文提出了基于遥感时空知识图谱一阶逻辑推理的变化图斑自动净化技术。为了提升遥感时空知识图谱的并发处理与人机交互核验效率,本文研发了一套遥感时空知识图谱管理服务系统。【结果】针对广东省2024年3—6月自然资源要素变化图斑净化任务,本文方法的存真率达到95.37%、去伪率达到21.82%。【结论】本文提出的自然资源要素变化图斑智能净化算法及系统能够在充分保留真实变化图斑的条件下,可以高效剔除虚警变化图斑,显著提升自然资源要素变化监测作业效率。 展开更多
关键词 时空知识图谱 自然资源要素变化监测 图数据库空间计算 遥感大模型 一阶逻辑推理 遥感影像变化检测 大语言模型 时空智能
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Characterization of Cassava Root Husk Powder: Equilibrium, Kinetic and Modeling Studies as Bioadsorbent for Copper(II) and Lead(II)
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作者 Kaupa Philip Rebecca Jacob Janarthanan Gopalakrishnan 《Journal of Encapsulation and Adsorption Sciences》 2021年第2期69-86,共18页
This study was aimed to investigate Pb(II) and Cu(II) ions removal ability from aqueous solution by cassava root husks (CRH) as a cheap, sustainable and eco<span>-</span><span><span>friendly bi... This study was aimed to investigate Pb(II) and Cu(II) ions removal ability from aqueous solution by cassava root husks (CRH) as a cheap, sustainable and eco<span>-</span><span><span>friendly bioadsorbent. The CRH was characterized by Fourier Transform Infrared (FTIR) spectroscopy which indicated the availability of various functional groups for metal coordination and the result was supported by elemental analysis studies. UV-Visible spectral studies indicated the presence of oxalate (</span><img src="Edit_88f5f86a-6e96-4764-8dc0-31bbb7ac83c6.png" width="34" height="18" alt="" /></span><span><span></span><span><span>) </span><span>and it could possibly interact with metal ions to give rise to a stable chelated coordination complex which affects metal ions removal efficiency. Bioadsorption process was carried out as a function of metal concentration, contact time, pH of the solution, particle size</span></span><span>,</span><span> and dosage of the adsorbent. Experimental results indicated the optimal adsorption condition of pH 4 for both Pb(II) and Cu(II) ions, dosage of 0.1</span><span style="font-family:;" "=""> </span><span>g/0.1L and 1</span><span style="font-family:;" "=""> </span><span>g/0.1L for Pb(II) and Cu(II) ions respectively, adsorption equilibrium time of 2 and 25 minutes for Pb(II) and Cu(II) respectively, and concentration of 0.5 mg/L for both metal ions. Kinetic data best</span><span style="font-family:;" "=""> </span><span>fitted pseudo-second-order model and not </span><span>the </span><span>pseudo-first-order model. Equilibrium data best fitted </span><span>the </span><span>Freundlich model than </span><span>the </span><span>Langmuir model. Specific surface area and pore volume studies indicated that CRH is non-porous and hence rapid adsorption kinetics is expected. Supporting the experimental results, molecular modeling studies performed using Schr<span style="white-space:nowrap;">&ouml</span>dinger software predicted several sites in the structure capable of docking with metal ions.</span></span> 展开更多
关键词 Bioadsorption Langmuir Isotherm Freundlich Isotherm Pseudo-first-order Kinetics Pseudo-Second-order Kinetics Cassava Root Husk Molecular modeling
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广西大瑶山国家级自然保护区不同海拔森林土壤有机碳矿化特征 被引量:3
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作者 黄远泽 胡彬 +5 位作者 张凌睿 徐武 蒙检 卢峰 金恒 覃林 《环境生态学》 2025年第1期46-52,130,共8页
研究不同海拔森林土壤有机碳矿化特征对于深入理解山地森林生态系统碳循环具有重要意义。以广西大瑶山国家级自然保护区不同海拔的常绿阔叶林(660 m)、针阔混交林(1430 m)和高山矮林(1750 m)为研究对象,基于各森林类型土壤(0~10 cm)室... 研究不同海拔森林土壤有机碳矿化特征对于深入理解山地森林生态系统碳循环具有重要意义。以广西大瑶山国家级自然保护区不同海拔的常绿阔叶林(660 m)、针阔混交林(1430 m)和高山矮林(1750 m)为研究对象,基于各森林类型土壤(0~10 cm)室内25℃矿化培养试验,探讨南亚热带向中亚热带过渡区不同海拔森林土壤有机碳的矿化特征。结果表明,在40 d培养期内,高海拔森林土壤有机碳累积矿化量、矿化速率均显著高于低海拔森林土壤(p<0.05)。土壤有机碳(SOC)与土壤矿化速率正相关,含量更高的土壤有机碳提供了更多的矿化底物能够支持更高的微生物量,同时还有利于惰性土壤有机碳向易分解有机碳转化从而利于土壤有机碳的分解。全氮(TN)增加会显著降低反硝化功能基因丰度,增加土壤有效氮含量,促进微生物生物量增加,并促进微生物分泌获取能量的酶活性,有利于提高土壤有机碳矿化速率。不同海拔森林土壤有机碳矿化过程能用一阶动力学模型较好地拟合。海拔梯度上,土壤有机碳潜在矿化量(C_(p))高海拔森林土壤显著高于低海拔森林土壤,但土壤矿化速率常数(k)却是高海拔森林显著小于低海拔森林(p<0.05)。Mantle test和随机森林回归分析结果表明,TN和SOC是影响C_(p)的重要因素,而k主要受硝态氮(NO_(3)^(-)-N)和SOC的制约。总之,在全球气候持续变暖趋势下,该保护区高海拔森林土壤预计将释放更多的CO_(2),从而对大气条件产生较大影响。 展开更多
关键词 森林类型 土壤有机碳 海拔 有机碳矿化 一阶动力学模型
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基于指数积理论的数控机床加工精度可靠性分析
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作者 王智明 许腾 周健 《兰州理工大学学报》 北大核心 2025年第5期46-53,共8页
数控机床的加工精度是影响产品质量的重要因素.为了提高多轴数控机床的加工精度可靠性,基于指数积理论建立了机床几何误差模型和加工精度可靠性模型.采用改进的一次二阶矩法,分析了机床加工精度的可靠性和几何误差项的灵敏度,提出了通... 数控机床的加工精度是影响产品质量的重要因素.为了提高多轴数控机床的加工精度可靠性,基于指数积理论建立了机床几何误差模型和加工精度可靠性模型.采用改进的一次二阶矩法,分析了机床加工精度的可靠性和几何误差项的灵敏度,提出了通用的机床精度分配方法.该方法不仅给出了机床垂直度误差的物理意义,而且解决了矩阵奇异问题.以大型数控导轨磨床为例,根据几何误差项的灵敏度进行分析,通过优化调整主要几何误差项提高磨床的加工精度可靠性.结果表明,该精度分配方法有效可行. 展开更多
关键词 精度分配 改进的一次二阶矩法 加工精度可靠性 指数积模型
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基于HBF神经网络观测器的PMSM无模型预测电流控制
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作者 马炳图 杜钦君 +2 位作者 张婷 李伟强 刘家合 《仪器仪表学报》 北大核心 2025年第8期376-386,共11页
针对风电机组变桨系统永磁同步电机(PMSM)在复杂运行环境中参数时变引发的模型失配难题,提出了一种融合超局部建模、HBF神经网络观测器以及改进双矢量调制的PMSM无模型预测电流控制(HBF-MFPCC)方案。根据一阶超局部模型原理构建了PMSM... 针对风电机组变桨系统永磁同步电机(PMSM)在复杂运行环境中参数时变引发的模型失配难题,提出了一种融合超局部建模、HBF神经网络观测器以及改进双矢量调制的PMSM无模型预测电流控制(HBF-MFPCC)方案。根据一阶超局部模型原理构建了PMSM无模型预测电流控制的预测模型,仅需使用电机的电流和电压等历史信息即可预测未来时刻的电流值,彻底摆脱对电机电阻、电感和磁链等参数的依赖,解决了传统模型预测电流控制(MPCC)依赖于精确电机参数的问题;设计了一种HBF神经网络观测器来对预测模型的集总误差进行快速辨识,采用决策树优化基函数中心与宽度,该观测器具有较高的辨识速度和适应性,能够有效提高预测模型的准确度;采用一种改进的双矢量最优占空比调制策略,从19组电压矢量组合中选择最优矢量作用于逆变器,并通过自适应时长分配抑制电流纹波,提高电流的跟踪性能。仿真和实验结果表明,在模拟极端参数失配的工况下,提出的HBF-MFPCC策略相比MPCC策略能够使电流跟踪误差降低50%,谐波失真率降低28%;设计的HBF神经网络观测器能够使电流跟踪误差降低53%,谐波失真率降低55%;改进双矢量调制方法能够使电流跟踪误差降低24%,谐波失真率降低11%;该方案能够显著提高系统的鲁棒性且保证良好的电流跟踪性能。 展开更多
关键词 风力发电机 永磁同步电机 无模型预测电流控制 一阶超局部模型 神经网络观测器 双矢量控制
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