资源类型

期刊论文 1638

年份

2024 41

2023 93

2022 109

2021 103

2020 82

2019 106

2018 87

2017 90

2016 66

2015 89

2014 83

2013 63

2012 84

2011 72

2010 74

2009 54

2008 73

2007 88

2006 36

2005 24

展开 ︾

关键词

风险分析 9

分析 4

可持续发展 4

对策 4

影响因素 4

数值模拟 4

隧道 4

ANSYS 3

数值分析 3

秦巴山脉区域 3

裂缝 3

2035年 2

BNLAS 2

COVID-19 2

DX桩 2

HIV感染孕产妇 2

“一带一路” 2

三峡工程 2

专利分析 2

展开 ︾

检索范围:

排序: 展示方式:

A neural network-based production process modeling and variable importance analysis approach in corn

《化学科学与工程前沿(英文)》 2023年 第17卷 第3期   页码 358-371 doi: 10.1007/s11705-022-2190-y

摘要: Corn to sugar process has long faced the risks of high energy consumption and thin profits. However, it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of the related processes. Big data technology provides a promising solution as its ability to turn huge amounts of data into insights for operational decisions. In this paper, a neural network-based production process modeling and variable importance analysis approach is proposed for corn to sugar processes, which contains data preprocessing, dimensionality reduction, multilayer perceptron/convolutional neural network/recurrent neural network based modeling and extended weights connection method. In the established model, dextrose equivalent value is selected as the output, and 654 sites from the DCS system are selected as the inputs. LASSO analysis is first applied to reduce the data dimension to 155, then the inputs are dimensionalized to 50 by means of genetic algorithm optimization. Ultimately, variable importance analysis is carried out by the extended weight connection method, and 20 of the most important sites are selected for each neural network. The results indicate that the multilayer perceptron and recurrent neural network models have a relative error of less than 0.1%, which have a better prediction result than other models, and the 20 most important sites selected have better explicable performance. The major contributions derived from this work are of significant aid in process simulation model with high accuracy and process optimization based on the selected most important sites to maintain high quality and stable production for corn to sugar processes.

关键词: big data     corn to sugar factory     neural network     variable importance analysis    

Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

《机械工程前沿(英文)》 2021年 第16卷 第4期   页码 711-725 doi: 10.1007/s11465-021-0647-1

摘要: The safety of human–robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human–robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional–derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

关键词: variable stiffness actuator     variable stiffness module     drive module     symmetrical structure     double-deck grooves     expandable electrical system    

An isogeometric approach to free vibration analysis of bi-directional functionally graded porous doubly-curvedshallow microshells with variable length-scale parameters

《结构与土木工程前沿(英文)》 2023年 第17卷 第12期   页码 1871-1894 doi: 10.1007/s11709-023-0021-y

摘要: This study uses iso-geometric investigation, which is based on the non-uniform rational B-splines (NURBS) basis function, to investigate natural oscillation of bi-directional functionally graded porous (BFGP) doubly-curved shallow microshells placed on Pasternak foundations with any boundary conditions. The characteristics of the present material vary in both thickness and axial directions along the x-axis. To be more specific, a material length-scale coefficient of the microshell varies in both thickness and length directions as the material’s mechanical properties. One is able to develop a differential equation system with varying coefficients that regulate the motion of BFGP double-curved shallow microshells by using Hamilton principle, Kirchhoff–Love hypothesis, and modified couple stress theory. The numerical findings are reported for thin microshells that are spherical, cylindrical, and hyperbolic paraboloidal, with a variety of planforms, including rectangles and circles. The validity and effectiveness of the established model are shown by comparing the numerical results given by the proposed formulations with previously published findings in many specific circumstances. In addition, influences of length scale parameters, power-law indexes, thickness-to-side ratio, and radius ratio on natural oscillation responses of BFGP microshells are investigated in detail.

关键词: Kirchhoff–Love’s shell theory     isogeometric analysis     bi-directional functionally graded     free vibration     variable length-scale parameter    

An isogeometric approach to static and transient analysis of fluid-infiltrated porous metal foam piezoelectricnanoplates with flexoelectric effects and variable nonlocal parameters

《结构与土木工程前沿(英文)》 2024年 第18卷 第3期   页码 461-489 doi: 10.1007/s11709-024-1061-7

摘要: In this work, a novel refined higher-order shear deformation plate theory is integrated with nonlocal elasticity theory for analyzing the free vibration, bending, and transient behaviors of fluid-infiltrated porous metal foam piezoelectric nanoplates resting on Pasternak elastic foundation with flexoelectric effects. Isogeometric analysis (IGA) and the Navier solution are applied to the problem. The innovation in the present study is that the influence of the in-plane variation of the nonlocal parameter on the free and forced vibration of the piezoelectric nanoplates is investigated for the first time. The nonlocal parameter and material characteristics are assumed to be material-dependent and vary gradually over the thickness of structures. Based on Hamilton’s principle, equations of motion are built, then the IGA approach combined with the Navier solution is used to analyze the static and dynamic response of the nanoplate. Lastly, we investigate the effects of the porosity coefficients, flexoelectric parameters, elastic stiffness, thickness, and variation of the nonlocal parameters on the mechanical behaviors of the rectangular and elliptical piezoelectric nanoplates.

关键词: isogeometric analysis     fluid-infiltrated porous     piezoelectric nanoplates     static and transient analysis     flexoelectric effect     variable nonlocal parameters    

Performance analysis of a centrifugal compressor with variable inlet guide vanes

XIAO Jun, GU Chuangang, SHU Xinwei, GAO Chuang

《能源前沿(英文)》 2007年 第1卷 第4期   页码 473-476 doi: 10.1007/s11708-007-0070-6

摘要: The flow in a centrifugal compressor stage with variable inlet guide vanes (VIGVs) is investigated by numerical simulation in this paper. Analysis of the performance curves and relative velocity vectograms indicates that performan

关键词: performance     numerical simulation     performan     centrifugal compressor    

The critical importance of epigenetics in autoimmune-related skin diseases

《医学前沿(英文)》 2023年 第17卷 第1期   页码 43-57 doi: 10.1007/s11684-022-0980-8

摘要: Autoimmune-related skin diseases are a group of disorders with diverse etiology and pathophysiology involved in autoimmunity. Genetics and environmental factors may contribute to the development of these autoimmune disorders. Although the etiology and pathogenesis of these disorders are poorly understood, environmental variables that induce aberrant epigenetic regulations may provide some insights. Epigenetics is the study of heritable mechanisms that regulate gene expression without changing DNA sequences. The most important epigenetic mechanisms are DNA methylation, histone modification, and noncoding RNAs. In this review, we discuss the most recent findings regarding the function of epigenetic mechanisms in autoimmune-related skin disorders, including systemic lupus erythematosus, bullous skin diseases, psoriasis, and systemic sclerosis. These findings will expand our understanding and highlight the possible clinical applications of precision epigenetics approaches.

关键词: epigenetics     autoimmune-related skin diseases     DNA methylation     histone modifications     noncoding RNAs    

Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect

Yuji CHEN, Qizhi LUO,

《结构与土木工程前沿(英文)》 2009年 第3卷 第4期   页码 352-356 doi: 10.1007/s11709-009-0057-7

摘要: In order to study the mechanics behavior of a thin-walled box continuous girder with variable cross-sections, using potential variation theories, considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement, and evolving five generalized displacements with the spline function, the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation, which was solved using the Newton-Raphon iterative method. The results of the calculation show that different shear lag warp functions to the cantilever, top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder reliably. The thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal cross-sections. The effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.

关键词: thin-walled box girder with variable cross-sections     potential variational theory     shear lag     large deflection problem    

Recent advances in system reliability optimization driven by importance measures

Shubin SI, Jiangbin ZHAO, Zhiqiang CAI, Hongyan DUI

《工程管理前沿(英文)》 2020年 第7卷 第3期   页码 335-358 doi: 10.1007/s42524-020-0112-6

摘要: System reliability optimization problems have been widely discussed to maximize system reliability with resource constraints. Birnbaum importance is a well-known method for evaluating the effect of component reliability on system reliability. Many importance measures (IMs) are extended for binary, multistate, and continuous systems from different aspects based on the Birnbaum importance. Recently, these IMs have been applied in allocating limited resources to the component to maximize system performance. Therefore, the significance of Birnbaum importance is illustrated from the perspective of probability principle and gradient geometrical sense. Furthermore, the equations of various extended IMs are provided subsequently. The rules for simple optimization problems are summarized to enhance system reliability by using ranking or heuristic methods based on IMs. The importance-based optimization algorithms for complex or large-scale systems are generalized to obtain remarkable solutions by using IM-based local search or simplification methods. Furthermore, a general framework driven by IM is developed to solve optimization problems. Finally, some challenges in system reliability optimization that need to be solved in the future are presented.

关键词: importance measure     system performance     reliability optimization     optimization rules     optimization algorithms    

节流性能优异的新型液体静压支承节流器

孟心斋,孟昭焱

《中国工程科学》 2005年 第7卷 第3期   页码 49-52

摘要:

传统的液体静压支承节流器存在严重缺陷,性能不佳,不能消除支承间隙随外加载荷增加而剧减的缺点,严重影响其实际应用。新型节流器节流变量指数b≥3,能够保持节流器进油与油囊排油速度接近一致。此外,当有外加载荷作用于支承时,油囊压力会升高,迫使节流变量产生附加增量,从而弥补了因油囊压力升高而减少供油量与油囊增加的排油量。因此,新型节流器能够保证在有外加载荷作用时支承间隙变化很小或近于不变。新型节流器节流性能优良,结构简单,成本低廉,体积较小,具有实用价值。

关键词: 变隙滑阀节流器     变隙薄板节流器     变径毛细管节流器     节流变量指数    

Importance measure-based maintenance strategy optimization: Fundamentals, applications and future directions

《工程管理前沿(英文)》 doi: 10.1007/s42524-024-4003-0

摘要: Numerous maintenance strategies have been proposed in the literature related to reliability. This paper focuses on the utilization of reliability importance measures to optimize maintenance strategies. We analyze maintenance strategies based on importance measures and identify areas lacking sufficient research. The paper presents principles and formulas for advanced importance measures within the context of optimizing maintenance strategies. Additionally, it classifies methods of maintenance strategy optimization according to importance measures and outlines the roles of these measures in various maintenance strategies. Finally, it discusses potential challenges that optimization of maintenance strategies based on importance measures may encounter with future technologies.

关键词: maintenance strategy     importance measure     reliability     maintenance cost    

Multiscale analysis-based peridynamic simulation of fracture in porous media

《结构与土木工程前沿(英文)》 2024年 第18卷 第1期   页码 1-13 doi: 10.1007/s11709-024-1043-9

摘要: The simulation of fracture in large-scale structures made of porous media remains a challenging task. Current techniques either assume a homogeneous model, disregarding the microstructure characteristics, or adopt a micro-mechanical model, which incurs an intractable computational cost due to its complex stochastic geometry and physical properties, as well as its nonlinear and multiscale features. In this study, we propose a multiscale analysis-based dual-variable-horizon peridynamics (PD) model to efficiently simulate macroscopic structural fracture. The influence of microstructures in porous media on macroscopic structural failure is represented by two PD parameters: the equivalent critical stretch and micro-modulus. The equivalent critical stretch is calculated using the microscale PD model, while the equivalent micro-modulus is obtained through the homogenization method and energy density equivalence between classical continuum mechanics and PD models. Numerical examples of porous media with various microstructures demonstrate the validity, accuracy, and efficiency of the proposed method.

关键词: porous media     multiscale     variable-horizon peridynamic     equivalent critical stretch     equivalent micro-modulus    

基于变量变换级数展开法的光波导矢量本征模分析

肖金标,孙小菡,张明德,丁东

《中国工程科学》 2001年 第3卷 第11期   页码 49-53

摘要:

基于变量变换级数展开法,获得了掩埋矩形光波导及脊形光波导的矢量本征模及其传播常数。变量 变换使无限平面映射成单位平两,从而使单位平面边界上的电磁场自然为零,消除了非物理反射,提高了计算 精度;另外,由于这种方法所导致的矩阵阶数小,因此计算效率较高。分析的结果与已发表的结果吻合较好, 可以为优化波导光电子器件的结构提供参考。

关键词: 变量变换级数展开法     光波导     矢量本征模分析    

Improved resilience measure for component recovery priority in power grids

《工程管理前沿(英文)》 2021年 第8卷 第4期   页码 545-556 doi: 10.1007/s42524-021-0161-5

摘要: Given the complexity of power grids, the failure of any component may cause large-scale economic losses. Consequently, the quick recovery of power grids after disasters has become a new research direction. Considering the severity of power grid disasters, an improved power grid resilience measure and its corresponding importance measures are proposed. The recovery priority of failed components after a disaster is determined according to the influence of the failed components on the power grid resilience. Finally, based on the data from the 2019 Power Yearbook of each city in Shandong Province, China, the power grid resilience after a disaster is analyzed for two situations, namely, partial components failure and failure of all components. Result shows that the recovery priorities of components with different importance measures vary. The resilience evaluations under different repair conditions prove the feasibility of the proposed method.

关键词: resilience measure     power grid     importance measure     component recovery    

Analysis of statistical thermodynamic model for binary protein adsorption equilibria on cation exchange

ZHOU Xiaopeng, SU Xueli, SUN Yan

《化学科学与工程前沿(英文)》 2007年 第1卷 第2期   页码 103-112 doi: 10.1007/s11705-007-0020-x

摘要: A study of nonlinear competitive adsorption equilibria of proteins is of fundamental importance in understanding the behavior of preparative chromatographic separation. This work describes the nonlinear binary protein adsorption equilibria on ion exchangers by the statistical thermodynamic (ST) model. The single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin (BSA) on SP Sepharose FF were determined by batch adsorption experiments in 0.05 mol/L sodium acetate buffer at three pH values (4.5, 5.0 and 5.5) and three NaCl concentrations (0.05, 0.10 and 0.15 mol/L) at pH 5.0. The ST model was found to depict the effects of pH and ionic strength on the single-component equilibria well, with model parameters depending on the pH and ionic strength. Moreover, the ST model gave acceptable fitting to the binary adsorption data with the fitted single-component model parameters, leading to the estimation of the binary ST model parameter. The effects of pH and ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories. Results demonstrate the availability of the ST model for describing nonlinear competitive protein adsorption equilibria in the presence of two proteins.

关键词: fundamental importance     single-component equilibria     acceptable fitting     hemoglobin     chromatographic separation    

new and best approach for early detection of rotor and stator faults in induction motors coupled to variable

Abderrahim ALLAL,Boukhemis CHETATE

《能源前沿(英文)》 2016年 第10卷 第2期   页码 176-191 doi: 10.1007/s11708-015-0386-2

摘要: Today, induction machines are playing, thanks to their robustness, an important role in world industries. Although they are quite reliable, they have become the target of various types of defects. Thus, for a long time, many research laboratories have been focusing their works on the theme of diagnosis in order to find the most efficient technique to predict a fault in an early stage and to avoid an unplanned stopping in the chain of production and costs ensuing. In this paper, an approach called Park’s vector product approach (PVPA) was proposed which was endowed with a dominant sensitivity in the case in which there would be rotor or stator faults. To show its high sensitivity, it was compared with the classical methods such as motor current signature analysis (MCSA) and techniques studied in recent publications such as motor square current signature analysis (MSCSA), Park’s vector square modulus (PVSM) and Park-Hilbert (P-H) (PVSM ). The proposed technique was based on three main steps. First, the three-phase currents of the induction motor led to a Park’s vector. Secondly, the proposed PVPA was calculated to show the distinguishing spectral signatures of each default and specific frequencies. Finally, simulation and experimental results were presented to confirm the theoretical assumptions.

关键词: induction motor     incipient broken bar     extended Park’s vector approach     spectral analysis     inter-turn short-circuit     Hilbert transform    

标题 作者 时间 类型 操作

A neural network-based production process modeling and variable importance analysis approach in corn

期刊论文

Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

期刊论文

An isogeometric approach to free vibration analysis of bi-directional functionally graded porous doubly-curvedshallow microshells with variable length-scale parameters

期刊论文

An isogeometric approach to static and transient analysis of fluid-infiltrated porous metal foam piezoelectricnanoplates with flexoelectric effects and variable nonlocal parameters

期刊论文

Performance analysis of a centrifugal compressor with variable inlet guide vanes

XIAO Jun, GU Chuangang, SHU Xinwei, GAO Chuang

期刊论文

The critical importance of epigenetics in autoimmune-related skin diseases

期刊论文

Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect

Yuji CHEN, Qizhi LUO,

期刊论文

Recent advances in system reliability optimization driven by importance measures

Shubin SI, Jiangbin ZHAO, Zhiqiang CAI, Hongyan DUI

期刊论文

节流性能优异的新型液体静压支承节流器

孟心斋,孟昭焱

期刊论文

Importance measure-based maintenance strategy optimization: Fundamentals, applications and future directions

期刊论文

Multiscale analysis-based peridynamic simulation of fracture in porous media

期刊论文

基于变量变换级数展开法的光波导矢量本征模分析

肖金标,孙小菡,张明德,丁东

期刊论文

Improved resilience measure for component recovery priority in power grids

期刊论文

Analysis of statistical thermodynamic model for binary protein adsorption equilibria on cation exchange

ZHOU Xiaopeng, SU Xueli, SUN Yan

期刊论文

new and best approach for early detection of rotor and stator faults in induction motors coupled to variable

Abderrahim ALLAL,Boukhemis CHETATE

期刊论文