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A review on membrane distillation in process engineering: design and exergy equations, materials and

《化学科学与工程前沿（英文）》 2022年第16卷第5期页码 592-613 doi: 10.1007/s11705-021-2105-3

摘要： One of the problems that most afflicts humanity is the lack of clean water. Water stress, which is the pressure on the quantity and quality of water resources, exists in many places throughout the World. Desalination represents a valid solution to the scarcity of fresh water and several technologies are already well applied and successful (such as reverse osmosis), producing about 100 million m³·d⁻¹ of fresh water. Further advances in the field of desalination can be provided by innovative processes such as membrane distillation. The latter is of particular interest for the treatment of waste currents from conventional desalination processes (for example the retentate of reverse osmosis) as it allows to desalt highly concentrated currents as it is not limited by concentration polarization phenomena. New perspectives have enhanced research activities and allowed a deeper understanding of mass and heat transport phenomena, membrane wetting, polarization phenomena and have encouraged the use of materials particularly suitable for membrane distillation applications. This work summarizes recent developments in the field of membrane distillation, studies for module length optimization, commercial membrane modules developed, recent patents and advancement of membrane material.

关键词： membrane distillation recent developments heat and mass transfer wetting membrane material

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Parametric equations for notch stress concentration factors of rib–deck welds under bending loading

《结构与土木工程前沿（英文）》 2021年第15卷第3期页码 595-608 doi: 10.1007/s11709-021-0720-1

摘要： The effective notch stress approach for evaluating the fatigue strength of rib–deck welds requires notch stress concentration factors obtained from complex finite element analysis. To improve the efficiency of the approach, the notch stress concentration factors for three typical fatigue-cracking modes (i.e., root–toe, root–deck, and toe–deck cracking modes) were thoroughly investigated in this study. First, we developed a model for investigating the effective notch stress in rib–deck welds. Then, we performed a parametric analysis to investigate the effects of multiple geometric parameters of a rib–deck weld on the notch stress concentration factors. On this basis, the multiple linear stepwise regression analysis was performed to obtain the optimal regression functions for predicting the notch stress concentration factors. Finally, we employed the proposed formulas in a case study. The notch stress concentration factors estimated from the developed formulas show agree well with the finite element analysis results. The results of the case study demonstrate the feasibility and reliability of the proposed formulas. It also shows that the fatigue design curve of FAT225 seems to be conservative for evaluating the fatigue strength of rib–deck welds.

关键词： notch stress concentration factor rib–deck weld parametric analysis regression analysis parametric equation

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Solving nonlinear differential equations of Vanderpol, Rayleigh and Duffing by AGM

null

《机械工程前沿（英文）》 2014年第9卷第2期页码 177-190 doi: 10.1007/s11465-014-0288-8

摘要：

In the present paper, three complicated nonlinear differential equations in the field of vibration, which are Vanderpol, Rayleigh and Duffing equations, have been analyzed and solved completely by Algebraic Method (AGM). Investigating this kind of equations is a very hard task to do and the obtained solution is not accurate and reliable. This issue will be emerged after comparing the achieved solutions by numerical method (Runge-Kutte 4th). Based on the comparisons which have been made between the gained solutions by AGM and numerical method, it is possible to indicate that AGM can be successfully applied for various differential equations particularly for difficult ones. The results reveal that this method is not only very effective and simple, but also reliable, and can be applied for other complicated nonlinear problems.

关键词： Algebraic Method (AGM) Angular Frequency Vanderpol Rayleigh Duffing

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Proca电磁理论的若干问题

黄志洵

《中国工程科学》 2005年第7卷第3期页码 6-12

摘要：

2004年6月，位于西非Oklo的美国Los Alamos实验室的核工业反应堆对实验数据做再分析后得出结论说，近20亿年内精细结构常数减小了4.5×10^-8。常数不常，意味着光速有很小的变化。这是最新的与狭义相对论不符的实验报告。另一方面，光子如有质量，Maxwell方程组将被Proca方程组所取代，而磁矢位（势）A将成为可观测量。而过去和现在都有许多方法测量光子的质量。

文章的主要目的是在Proca理论框架内研究电磁波波速，发现即使在自由空间（真空）条件下也会出现超光速传播；同时又对波导与Proca波的截止现象做了比较，给出了相应的结果。

关键词：狭义相对论 Maxwell方程组 Proca方程组电磁波波速光子的静止质量

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Degree of bending of concrete-filled rectangular hollow section K-joints under balanced-axial loadings

Rui ZHAO; Yongjian LIU; Lei JIANG; Yisheng FU; Yadong ZHAO; Xindong ZHAO

《结构与土木工程前沿（英文）》 2022年第16卷第4期页码 461-477 doi: 10.1007/s11709-022-0818-0

摘要： It has been found that the fatigue life of tubular joints is not only determined by the hot spot stress, but also by the stress distribution through the tube thickness represented as the degree of bending (DoB). Consequently, the DoB value should be determined to improve the accuracy of fatigue assessment for both stress-life curve and fracture mechanics methods. Currently, no DoB parametric formula is available for concrete-filled rectangular hollow section (CFRHS) K-joints, despite their wide use in bridge engineering. Therefore, a robust finite element (FE) analysis was carried out to calculate the DoB of CFRHS K-joints under balanced-axial loading. The FE model was developed and verified against a test result to ensure accuracy. A comprehensive parametric study including 190 models, was conducted to establish the relationships between the DoBs and four specific variables. Based on the numerical results, design equations to predict DoBs for CFRHS K-joints were proposed through multiple regression analysis. A reduction of 37.17% was discovered in the DoB, resulting in a decrease of 66.85% in the fatigue life. Inclusively, the CFRHS K-joints with same hot spot stresses, may have completely different fatigue lives due to the different DoBs.

关键词： fatigue assessment K-joint design equations degree of bending fracture mechanics

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Significant progress in solution of nonlinear equations at displacement of structure and heat transfer

M. R. AKBARI,D. D. GANJI,M. NIMAFAR,A. R. AHMADI

《机械工程前沿（英文）》 2014年第9卷第4期页码 390-401 doi: 10.1007/s11465-014-0313-y

摘要：

In this paper, we aim to promote the capability of solving two complicated nonlinear differential equations: 1) Static analysis of the structure with variable cross section areas and materials with slope-deflection method; 2) the problem of one dimensional heat transfer with a logarithmic various surface A(x) and a logarithmic various heat generation G(x) with a simple and innovative approach entitled “Akbari-Ganji’s method” (AGM). Comparisons are made between AGM and numerical method, the results of which reveal that this method is very effective and simple and can be applied for other nonlinear problems. It is significant that there are some valuable advantages in this method and also most of the differential equations sets can be answered in this manner while in other methods there is no guarantee to obtain the good results up to now. Brief excellences of this method compared to other approaches are as follows: 1) Differential equations can be solved directly by this method; 2) without any dimensionless procedure, equation(s) can be solved; 3) it is not necessary to convert variables into new ones. According to the aforementioned assertions which are proved in this case study, the process of solving nonlinear equation(s) is very easy and convenient in comparison to other methods.

关键词： AGM extended surface heat transfer slope-deflection method

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Scrutiny of non-linear differential equations Euler-Bernoulli beam with large rotational deviation by

M. R. AKBARI,M. NIMAFAR,D. D. GANJI,M. M. AKBARZADE

《机械工程前沿（英文）》 2014年第9卷第4期页码 402-408 doi: 10.1007/s11465-014-0316-8

摘要：

The kinematic assumptions upon which the Euler-Bernoulli beam theory is founded allow it to be extended to more advanced analysis. Simple superposition allows for three-dimensional transverse loading. Using alternative constitutive equations can allow for viscoelastic or plastic beam deformation. Euler-Bernoulli beam theory can also be extended to the analysis of curved beams, beam buckling, composite beams and geometrically nonlinear beam deflection. In this study, solving the nonlinear differential equation governing the calculation of the large rotation deviation of the beam (or column) has been discussed. Previously to calculate the rotational deviation of the beam, the assumption is made that the angular deviation of the beam is small. By considering the small slope in the linearization of the governing differential equation, the solving is easy. The result of this simplification in some cases will lead to an excessive error. In this paper nonlinear differential equations governing on this system are solved analytically by Akbari-Ganji’s method (AGM). Moreover, in AGM by solving a set of algebraic equations, complicated nonlinear equations can easily be solved and without any mathematical operations such as integration solving. The solution of the problem can be obtained very simply and easily. Furthermore, to enhance the accuracy of the results, the Taylor expansion is not needed in most cases via AGM manner. Also, comparisons are made between AGM and numerical method (Runge-Kutta 4th). The results reveal that this method is very effective and simple, and can be applied for other nonlinear problems.

关键词： AGM critical load of columns large deformations of beam nonlinear differential equation

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稳定线性热分层环境下火灾烟气羽流积分解及实验分析

方俊,疏学明,袁宏永,郑昕

《中国工程科学》 2004年第6卷第1期页码 37-43

摘要：

对稳定线性热分层环境下湍浮力羽流无量纲积分方程首次采用数值解法进行求解，得出浮力通量、动量通量等参量在轴线上的变化规律以及羽流中性浮力点的高度和羽流最大上升高度。2种不同尺度空间及不同烟气羽流出口条件的实验表明，实际火灾烟气羽流最大上升高度与理论计算结果及文献经验公式相符，从而表明积分模型数值解的有效性，并为高大空间火灾烟气输运规律研究及探测技术发展提供了理论及实验依据。

关键词：稳定线性热分层环境火灾烟气羽流积分解实验分析

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数据驱动的随机微分方程辨识 Article

王亚森, 方华臻, 金骏阳, 马贵君, 何心, 代星, 岳作功, 程骋, 张海涛, 浦栋麟, 伍冬睿, 袁烨, Jorge Gonçalves, Jürgen Kurths, 丁汉

《工程（英文）》 2022年第17卷第10期页码 244-252 doi: 10.1016/j.eng.2022.02.007

摘要：

随机微分方程（SDE）是一种广泛用于描述受不同来源噪声干扰的复杂过程或现象的数学模型。由于数据固有的强随机性和系统动力学的复杂性，控制系统的SDE的辨识通常是一个挑战。辨识SDE的现有参数化方法的实用性通常受到数据资源不足的限制。本研究提出了一种通过稀疏贝叶斯学习（SBL）技术从候选基函数空间中搜索简洁但物理必需的表示形式来辨识SDE的新框架。更重要的是，利用SBL的解析可处理性开发了一种可以通过少量数据来高效地构建辨识SDE的线性回归模型的方法。本文利用股票和石油价格、轴承变化和风速的真实数据，以及包括广义维纳（Wiener）过程和朗之万方程在内的著名随机动力系统的仿真数据，验证了所提出框架的有效性。该框架旨在帮助专家从自然科学、经济学和工程领域的随机现象中提取随机数学模型，用于分析、预测和决策。

关键词：数据驱动方法系统辨识稀疏贝叶斯学习随机微分方程随机现象

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Burnett simulations of gas flow and heat transfer in microchannels

Fubing BAO, Jianzhong LIN

《机械工程前沿（英文）》 2009年第4卷第3期页码 252-263 doi: 10.1007/s11465-009-0037-6

摘要： In micro- and nanoscale gas flows, the flow falls into the transition flow regime. There are not enough molecule collisions and the gas deviates from the equilibrium. The Navier-Stokes equations fail to describe the gas flow in this regime. The direct simulation Monte Carlo method converges slowly and requires lots of computational time. As a result, the high-order Burnett equations are used to study the gas flow and heat transfer characteristics in micro- and nanoscale gas flows in this paper. The Burnett equations are first reviewed, and the augmented Burnett equations with high-order slip boundary conditions are then used to model the gas flow and heat transfer in Couette and Poiseuille flows in the transition regime.

关键词： micro- and nanoscale gas flow slip-transition flow regime Burnett equations numerical simulation

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混凝土裂缝端部粘聚力的计算

徐世烺,王利民

《中国工程科学》 2002年第4卷第5期页码 53-58

摘要：

混凝土裂缝端部断裂过程区的粘聚力分布是导致混凝土断裂呈现非线性特性的重要原因。基于混凝土的断裂特性和虚拟裂缝端部存在粘聚力的分析模型，并通过分布函数的特性分析，提出了粘聚力分布函数的两种简化表达式：一为单参数待定式，另一为双参数待定式。由变形体叠加原理，推导出计算单参数待定函数公式和计算双参数待定函数代数方程组。进而通过裂缝张开位移实测数据即可求得粘聚力分布，并且给出了适当的算例分析和讨论。

关键词：混凝土裂缝张开位移虚拟裂缝粘聚力代数方程

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Modeling and analysis of landing collision dynamics for a shipborne helicopter

Dingxuan ZHAO, Haojie YANG, Carbone GIUSEPPE, Wenhang LI, Tao NI, Shuangji YAO

《机械工程前沿（英文）》 2021年第16卷第1期页码 151-162 doi: 10.1007/s11465-020-0617-z

摘要： A Lagrange dynamic model is established based on small-angle approximation to improve the simulation model for shipborne helicopter landing collision. To describe fuselage motion effectively, the proposed model considers ship motion, the interaction of the tires with the deck, and tire slippage. A mechanism of sliding motion is built, and a real-time reliability analysis of the algorithm is implemented to validate the proposed model. Numerical simulations are also conducted under different operation conditions. Results show that the proposed dynamic model can simulate the collision motion of helicopter landing in real time. Several suggestions for helicopter pilot landing are likewise provided.

关键词： shipborne helicopter landing model Lagrange equations dynamics validation

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Measurement and correlation of supercritical CO

Hiroshi MACHIDA, Ryosuke TAGUCHI, Yoshiyuki SATO, Louw J. FLOURUSSE, Cor J. PETERS, Richard L. SMITH

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 12-19 doi: 10.1007/s11705-009-0151-3

摘要： Ionicliquids combined with supercritical fluid technology hold great promise as working solvents for developing compact processes. Ionic liquids, which are organic molten salts, typically have extremely low volatility and high functionality, but possess high viscosities, surface tensions and low diffusion coefficients, which can limit their applicability. CO , on the other hand, especially in its supercritical state, is a green solvent that can be used advantageously when combined with the ionic liquid to provide viscosity and surface tension reduction and to promote mass transfer. The solubility of CO in the ionic liquid is key to estimating the important physical properties that include partition coefficients, viscosities, densities, interfacial tensions, thermal conductivities and heat capacities needed in contactor design. In this work, we examine a subset of available high pressure pure component ionic liquid PVT data and high pressure CO - ionic liquid solubility data and report new correlations for CO -ionic liquid systems with equations of state that have some industrial applications including: (1) general, (2) fuel desulfurization, (3) CO capture, and (4) chiral separation. New measurements of solubility data for the CO and 1-butyl-3-methylimidazolium octyl sulfate, [bmim][OcSO ] system are reported and correlated. In the correlation of the CO ionic liquid phase behavior, the Peng-Robinson and the Sanchez-Lacombe equations of state were considered and are compared. It is shown that excellent correlation of CO solubility can be obtained with either equation and they share some common characteristics regarding interaction parameters. In the Sanchez-Lacombe equation, parameters that are derived from the supercritical region were found to be important for obtaining good correlation of the CO -ionic liquid solubility data.

关键词： compact processes chiral ionic liquids separations thermodynamic properties equations of state

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Prediction of bed load sediments using different artificial neural network models

Reza ASHEGHI, Seyed Abbas HOSSEINI

《结构与土木工程前沿（英文）》 2020年第14卷第2期页码 374-386 doi: 10.1007/s11709-019-0600-0

摘要： Modeling and prediction of bed loads is an important but difficult issue in river engineering. The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured data. In this paper, three different artificial neural networks (ANNs) including multilayer percepterons, radial based function (RBF), and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were developed. The optimum models were found through 102 data sets of flow discharge, flow velocity, water surface slopes, flow depth, and mean grain size. The deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed data. The coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN models. The accuracy performance of all models was evaluated and interpreted using different statistical error criteria, analytical graphs and confusion matrixes. Although the ANN models predicted compatible outputs but the RBF with 79% correct classification rate corresponding to 0.191 network error was outperform than others.

关键词： bed load prediction artificial neural network modeling empirical equations

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纳米多孔介质中的流体流动

Weiyao Zhu,Bin Pan,Zhen Chen,Wengang Bu,Qipeng Ma,Kai Liu,Ming Yue

《工程（英文）》 2024年第32卷第1期页码 139-152 doi: 10.1016/j.eng.2023.05.014

摘要：

Fluid flow at nanoscale is closely related to many areas in nature and technology, e.g., unconventional hydrocarbon recovery, carbon dioxide geo-storage, underground hydrocarbon storage, fuel cells, ocean desalination and biomedicine. At nanoscale, interfacial forces dominate over bulk forces, and nonlinear effects are important, which significantly deviate from conventional theory. During the past decades, a series of experiments, theory and simulations have been performed to investigate fluid flow at nanoscale, which has advanced our fundamental knowledge of this topic. However, a critical review is still lacking, which has seriously limited the basic understanding of this area. Therefore herein, we systematically review experimental, theoretical and simulation works on single- and multi- phases fluid flow at nanoscale. We also clearly point out the current research gaps and future outlook. These insights will promote the significant development of nonlinear flow physics at nanoscale and will provide crucial guidance on the relevant areas.

关键词： Transport in nanoporous media Multi-phase fluid dynamics Nonlinear flow mechanisms Nonlinear flow conservation equations Interfacial forces Molecular dynamics simulation