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Significant progress in solution of nonlinear equations at displacement of structure and heat transfer extendedsurface by new AGM approach

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    

Optimal design analysis of a tubular heat exchanger network with extended surfaces using multi-objective

Hassan HAJABDOLLAHI, Mohammad SHAFIEY DEHAJ, Babak MASOUMPOUR, Mohammad ATAEIZADEH

《能源前沿(英文)》 2022年 第16卷 第5期   页码 862-875 doi: 10.1007/s11708-022-0839-3

摘要: The present work aims to investigate the influence of extended surfaces (fins) on the multi-objective optimization of a tubular heat exchanger network (THEN). An increase in the heat transfer area using various extended surfaces (fins) to enhance the performance of the heat exchanger was used while considering the effectiveness and total heat transfer area as two objective functions. In addition to the simulation of simple fins, a new set of fins, called constructal fins, was designed based on the constructal theory. Tubular heat exchanger network design parameters were chosen as optimization variables, and optimization results were achieved in such a way as to enhance the effectiveness and decrease the total heat transfer area. The results show the importance of constructal fins in improving the objective functions of heat exchangers. For instance, the simple fins case enhances the effectiveness by up to 5.3% compared to that without fins (usual heat exchanger) while using constructal fins, in addition to the 7% increment of effectiveness, reduces the total heat transfer area by 9.47%. In order to optimize the heat exchanger, the heat transfer rate and cold fluid temperature must increase, and at the same time, the hot exiting fluid temperature should decrease at the same constant total heat transfer area, which is higher in the constructal fins case. Finally, optimized design variables were studied for different cases, and the effects of various fins were reported.

关键词: constructal theory     extended surface     effectiveness     total heat transfer area     multi-objective optimization    

Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

《结构与土木工程前沿(英文)》 2015年 第9卷 第4期   页码 441-447 doi: 10.1007/s11709-015-0319-5

摘要: This is the first manuscript presenting an extended meshfree method for thermo- elastic fracture which does not exploit a crack tip enrichment. The crack is modeled by partition of unity enrichment of the displacement and temperature field. Only a step function is employed that facilitates the implementation. To ensure that crack tip is at the correct position, a Lagrange multiplier field ahead of the crack tip is introduced along a line. The Lagrange multiplier nodal parameters are discretised with the available meshfree functions. Two benchmark examples illustrate the efficiency of the method.

关键词: meshfree method     thermo-elasticity    

Concurrent fatigue crack growth simulation using extended finite element method

Zizi LU, Yongming LIU,

《结构与土木工程前沿(英文)》 2010年 第4卷 第3期   页码 339-347 doi: 10.1007/s11709-010-0078-2

摘要: In this paper, a concurrent simulation framework for fatigue crack growth analysis is proposed using a novel small time scale model for fatigue mechanism analysis and the extended finite element method (X-FEM) for fatigue crack growth simulation. The proposed small time scale fatigue model does not require the cycle counting as those using the classical fatigue analysis methods and can be performed concurrently with structural/mechanical analysis. The X-FEM greatly facilitates crack growth simulation without remeshing requirements ahead of the crack tip as in the classical finite element method. The basic concept and theory of X-FEM was briefly introduced and numerical predictions of stress intensity factors are verified with reference solutions under both uniaxial and multiaxial loadings. The small time scale fatigue model is integrated into the numerical simulation algorithm for concurrent fatigue crack growth analysis. Model predictions are compared with available experimental observations for model validation.

关键词: small time scale model     extended finite element method (X-FEM)     crack growth     multiaxial    

Sensorless direct torque control for salient-pole PMSM based on extended Kalman filter fed by AC/DC/AC

F. BENCHABANE, A. TITAOUINE, O. BENNIS, K. YAHIA, D. TAIBI, A. GUETTAF

《能源前沿(英文)》 2012年 第6卷 第3期   页码 247-254 doi: 10.1007/s11708-012-0190-1

摘要: In this paper, a new sensorless interior permanent magnet synchronous motor (IPMSM) drives method with extended Kalman filter (EKF) for speed, rotor position and load torque estimation is proposed. The direct torque control (DTC) technique for permanent magnet synchronous motor (PMSM) is receiving increasing attention due to the important advantages of the low dependence on motor parameters when compared with other motor control techniques. The Kalman filter is an observer for linear and non-linear systems and is based on the stochastic intromission, in others words, noise. The PMSM is fed by an indirect power electronic converter which is controlled by a sliding mode technique. The simulation tests performed for different operating conditions have confirmed the robustness of the overall system; and it is shown that the sliding mode technique has successfully minimized the different harmonics introduced by the line converter.

关键词: direct torque control (DTC)     sensorless control     extended Kalman filter (EKF)     permanent magnet synchronous motor (PMSM)     boost-rectifier    

Uncertainty propagation analysis by an extended sparse grid technique

X. Y. JIA, C. JIANG, C. M. FU, B. Y. NI, C. S. WANG, M. H. PING

《机械工程前沿(英文)》 2019年 第14卷 第1期   页码 33-46 doi: 10.1007/s11465-018-0514-x

摘要: In this paper, an uncertainty propagation analysis method is developed based on an extended sparse grid technique and maximum entropy principle, aiming at improving the solving accuracy of the high-order moments and hence the fitting accuracy of the probability density function (PDF) of the system response. The proposed method incorporates the extended Gauss integration into the uncertainty propagation analysis. Moreover, assisted by the Rosenblatt transformation, the various types of extended integration points are transformed into the extended Gauss-Hermite integration points, which makes the method suitable for any type of continuous distribution. Subsequently, within the sparse grid numerical integration framework, the statistical moments of the system response are obtained based on the transformed points. Furthermore, based on the maximum entropy principle, the obtained first four-order statistical moments are used to fit the PDF of the system response. Finally, three numerical examples are investigated to demonstrate the effectiveness of the proposed method, which includes two mathematical problems with explicit expressions and an engineering application with a black-box model.

关键词: uncertainty propagation analysis     extended sparse grid     maximum entropy principle     extended Gauss integration     Rosenblatt transformation     high-order moments analysis    

An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memory

S. HASHEMI,H. AHMADIAN,S. MOHAMMADI

《结构与土木工程前沿(英文)》 2015年 第9卷 第4期   页码 466-477 doi: 10.1007/s11709-015-0300-3

摘要: Thermo-mechanical coupling in shape memory alloys is a very complicated phenomenon. The heat generation/absorption during forward/reverse transformation can lead to temperature-dependent variation of its mechanical behavior in the forms of superelasticity and shape memory effect. However, unlike the usual assumption, slow loading rate cannot guarantee an isothermal process. A two-dimensional thermo-mechanically coupled algorithm is proposed based on the original model of Lagoudas to efficiently model both superelasticity and shape memory effects and the influence of various strain rates, aspect ratios and boundary conditions. To implement the coupled model into a finite element code, a numerical staggered algorithm is employed. A number of simulations are performed to verify the proposed approach with available experimental and numerical data and to assess its efficiency in solving complex SMA problems.

关键词: shape memory alloy     thermo-mechanical coupling     superplasticity     shape memory effect    

acid on natural magnetite and siderite: Evidence from sorption kinetics, sequential extraction and extended

《环境科学与工程前沿(英文)》 2022年 第16卷 第9期 doi: 10.1007/s11783-022-1547-2

摘要:

• DPAA sorption followed pseudo-secondary and intra-particle diffusion models.

关键词: Diphenylarsinic acid (DPAA)     Sorption     Magnetite     Siderite     Sequential extraction     EXAFS    

Towards a self-adaptive service-oriented methodology based on extended SOMA

Alireza PARVIZI-MOSAED,Shahrouz MOAVEN,Jafar HABIBI,Ghazaleh BEIGI,Mahdieh NASER-SHARIAT

《信息与电子工程前沿(英文)》 2015年 第16卷 第1期   页码 43-69 doi: 10.1631/FITEE.1400040

摘要: We propose a self-adaptive process (SAP) that maintains the software architecture quality using the MAPE-K standard model. The proposed process can be plugged into various software development processes and service-oriented methodologies due to its explicitly defined inputs and outputs. To this aim, the proposed SAP is integrated with the service-oriented modeling and application (SOMA) methodology in a two-layered structure to create a novel methodology, named self-adaptive service-oriented architecture methodology (SASOAM), which provides a semi-automatic self-aware method by the composition of architectural tactics. Moreover, the maintenance activity of SOMA is improved using architectural and adaptive patterns, which results in controlling the software architecture quality. The improvement in the maintainability of SOMA is demonstrated by an analytic hierarchy process (AHP) based evaluation method. Furthermore, the proposed method is applied to a case study to represent the feasibility and practicality of SASOAM.

关键词: Quality attribute     Adaptation pattern     Architectural tactic     Service-oriented architecture     Self-adaptive process     Architectural pattern    

“机械灌注+”应用于扩大标准供肝移植——肝尽其用 Review

王周城, Jack Martin, 余炯杰, 汪恺, Kourosh Saeb-Parsy, 徐骁

《工程(英文)》 2024年 第32卷 第1期   页码 30-41 doi: 10.1016/j.eng.2023.11.003

摘要:

移植是终末期肝病最有效的治疗方法,但由于供体器官的短缺而受到限制。扩大标准供体(ECD)供肝在临床实践中越来越多地用于缓解这一挑战。然而,这些移植物耐受缺血的能力下降,危及冷保存期间器官的活力。机器灌注(MP)旨在改善器官保存并减少移植后并发症。然而,越来越明显的是,单独使用MP无法达到ECD供肝的最佳保存。因此,人们逐渐开始重视改良的 MP 策略,包括使用不同的灌注剂、改良的灌注方式并结合不同的治疗干预策略。本文中,我们提出了“机械灌注+”的新理念,代表这些旨在提升器官功能并可能实现ECD供肝体外再生的机械灌注新策略。为此,我们总结了现有和改良的MP策略,并阐述其在临床场景中修复不同ECD供肝的优势。

关键词: 肝移植     扩大标准供体     机械灌注+     器官短缺    

用于毫米波焦面阵成像系统的扩展半球介质透镜

孙忠良,窦文斌

《中国工程科学》 2000年 第2卷 第3期   页码 42-47

摘要:

毫米波成像是近年来毫米波领域的一个研究热点,而焦面阵成像因其具有实时成像的优点更加受到重视。文中分析可用于焦面阵成像的扩展半球介质透镜。这种焦面阵成像结构将集成天线阵贴附在透镜背面接收透镜聚焦的功率,消除了集成天线工作在毫米波频段时存在的表面波对天线性能的影响,具有尺寸紧凑、损耗小的特点。采用Stmtton-Chu公式和射线追迹分析了电磁波人射到扩展半球透镜上时在其背面的场分布,即透镜的焦区场分布,以获得透镜用于焦面阵成像时的性能。为验证分析方法的正确性,对平面波垂直人射和会聚高斯束入射两种情形进行了实验验证,实验结果与理论分析吻合较好。该透镜天线还可用来消除常规集成毫米波系统中抛物面天线与集成前端之间的过渡,以降低损耗,改善系统性能,也可用于与准光系统的连接或耦合。该文结果将对上述应用提供理论指导。

关键词: 毫米波     天线     成像     扩展半球介质透镜    

Extended model predictive control scheme for smooth path following of autonomous vehicles

《机械工程前沿(英文)》 2022年 第17卷 第1期   页码 4-4 doi: 10.1007/s11465-021-0660-4

摘要: This paper presents an extended model predictive control (MPC) scheme for implementing optimal path following of autonomous vehicles, which has multiple constraints and an integrated model of vehicle and road dynamics. Road curvature and inclination factors are used in the construction of the vehicle dynamic model to describe its lateral and roll dynamics accurately. Sideslip, rollover, and vehicle envelopes are used as multiple constraints in the MPC controller formulation. Then, an extended MPC method solved by differential evolution optimization algorithm is proposed to realize optimal smooth path following based on driving path features. Finally, simulation and real experiments are carried out to evaluate the feasibility and the effectiveness of the extended MPC scheme. Results indicate that the proposed method can obtain the smooth transition to follow the optimal drivable path and satisfy the lateral dynamic stability and environmental constraints, which can improve the path following quality for better ride comfort and road availability of autonomous vehicles.

关键词: autonomous vehicles     vehicle dynamic modeling     model predictive control     path following     optimization algorithm    

Extended stochastic resonance (SR) and its applications in weak mechanical signal processing

Niaoqing HU, Min CHEN, Guojun QIN, Lurui XIA, Zhongyin PAN, Zhanhui FENG,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 450-461 doi: 10.1007/s11465-009-0072-3

摘要: To catch symptoms of machine failure as early as possible, one of the most important strategies is to apply more progressive techniques during signal processing. This paper presents a method based on stochastic resonance (SR) to detect weak fault signal. First, a discrete model of a bistable system that can demonstrate SR is researched, and the stability condition for controlling the selection of model parameters of the discrete model and guarantee the solving convergence are established. Then, the frequency range of the weak signals that the SR model can detect is extended through a type of normalized scale transformation. Finally, the method is applied to extract the weak characteristic component from heavy noise to indicate the little crack fault in a bearing outer circle.

关键词: extended stochastic resonance (SR)     stability analysis of SR     scale transform     weak signal detection     incipient fault detection     envelope analysis    

针对目标跟踪的两种基于最大期望算法测量值偏差估计过程的性能分析 None

Zhi-hua LU, Meng-yao ZHU, Qing-wei YE, Yu ZHOU

《信息与电子工程前沿(英文)》 2018年 第19卷 第9期   页码 1151-1165 doi: 10.1631/FITEE.1800214

摘要: 在现实目标跟踪问题中,传感器采集的测量值,比如系统缺陷,可能存在一定程度偏差。为正确估计目标的运动轨迹,测量值偏差的识别与估计将成为首要任务。首先,提出两种状态空间模型,分别把测量值偏差视为随机变量和常数。其次,假设测量值样本数足够大,基于最大期望算法,利用扩展卡尔曼滤波和平滑,针对两种模型提出不同的循环迭代偏差估计过程。最后,分析这两种估计过程的全局收敛结果,揭示其内在联系。结果表明,第二种估计过程比第一种估计过程更简单准确,并且收敛速度更快。批量处理测量值样本后,可同时获得目标运动轨迹和测量值偏差的估计结果。

关键词: 非线性状态空间模型;测量值偏差;扩展卡尔曼滤波;扩展卡尔曼平滑;最大期望算法    

Cell surface protein engineering for high-performance whole-cell catalysts

Hajime Nakatani,Katsutoshi Hori

《化学科学与工程前沿(英文)》 2017年 第11卷 第1期   页码 46-57 doi: 10.1007/s11705-017-1609-3

摘要: Cell surface protein engineering facilitated by accumulation of information on genome and protein structure involves heterologous production and modification of cell surface proteins using genetic engineering, and is important for the development of high-performance whole-cell catalysts. In this field, cell surface display is a major technology by exposing target proteins, such as enzymes, on the cell surface using a carrier protein. The target proteins are fused to the carrier proteins that transport and tether them to the cell surface, as well as to a secretion signal. This paper reviews cell surface display systems for prokaryotic and eukaryotic cells from the perspective of carrier proteins, which determine the number of displayed molecules, and the localization, size, and direction ( or terminal anchoring) of the passengers. We also discuss advanced methods for displaying multiple enzymes and a new method for the immobilization of whole-cell catalysts using adhesive surface proteins.

关键词: cell surface engineering     surface display     whole-cell catalysts     bioprocess    

标题 作者 时间 类型 操作

Significant progress in solution of nonlinear equations at displacement of structure and heat transfer extendedsurface by new AGM approach

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

期刊论文

Optimal design analysis of a tubular heat exchanger network with extended surfaces using multi-objective

Hassan HAJABDOLLAHI, Mohammad SHAFIEY DEHAJ, Babak MASOUMPOUR, Mohammad ATAEIZADEH

期刊论文

Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

期刊论文

Concurrent fatigue crack growth simulation using extended finite element method

Zizi LU, Yongming LIU,

期刊论文

Sensorless direct torque control for salient-pole PMSM based on extended Kalman filter fed by AC/DC/AC

F. BENCHABANE, A. TITAOUINE, O. BENNIS, K. YAHIA, D. TAIBI, A. GUETTAF

期刊论文

Uncertainty propagation analysis by an extended sparse grid technique

X. Y. JIA, C. JIANG, C. M. FU, B. Y. NI, C. S. WANG, M. H. PING

期刊论文

An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memory

S. HASHEMI,H. AHMADIAN,S. MOHAMMADI

期刊论文

acid on natural magnetite and siderite: Evidence from sorption kinetics, sequential extraction and extended

期刊论文

Towards a self-adaptive service-oriented methodology based on extended SOMA

Alireza PARVIZI-MOSAED,Shahrouz MOAVEN,Jafar HABIBI,Ghazaleh BEIGI,Mahdieh NASER-SHARIAT

期刊论文

“机械灌注+”应用于扩大标准供肝移植——肝尽其用

王周城, Jack Martin, 余炯杰, 汪恺, Kourosh Saeb-Parsy, 徐骁

期刊论文

用于毫米波焦面阵成像系统的扩展半球介质透镜

孙忠良,窦文斌

期刊论文

Extended model predictive control scheme for smooth path following of autonomous vehicles

期刊论文

Extended stochastic resonance (SR) and its applications in weak mechanical signal processing

Niaoqing HU, Min CHEN, Guojun QIN, Lurui XIA, Zhongyin PAN, Zhanhui FENG,

期刊论文

针对目标跟踪的两种基于最大期望算法测量值偏差估计过程的性能分析

Zhi-hua LU, Meng-yao ZHU, Qing-wei YE, Yu ZHOU

期刊论文

Cell surface protein engineering for high-performance whole-cell catalysts

Hajime Nakatani,Katsutoshi Hori

期刊论文