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Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要: The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词: adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

Recent development of vibration utilization engineering

WEN Bangchun

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 1-9 doi: 10.1007/s11465-008-0017-2

摘要: The utilization of vibration and wave, which was developed during the latter half of the 20th century, is one of the most valueable technology applications and has been rapidly developing recently . Because the technique is closely associated with industry and agriculture, it can create huge social and economical benefits and provide excellent services for society. Thus, due to its necessity in industry and daily life, extensive research has been devoted to vibration utillization engineering. In this paper, vibration utilization is classified into linear or non-linear vibrations, waves, and electric-magnetic oscillations. Their phenomena, patterns, and applications in nature and society are introduced. Some research results about vibration utilization engineering are described.

关键词: utilization engineering     non-linear     vibration     vibration utillization     utillization engineering    

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    

Chaotic behavior of LNG after stratification in main stream region of storage tank

WANG Jingjing, MA Xiaoqian

《能源前沿(英文)》 2008年 第2卷 第4期   页码 514-518 doi: 10.1007/s11708-008-0076-4

摘要: A study of the chaotic behavior of liquefied natural gas (LNG) after stratification in the main stream region of a storage tank was conducted. Based on non-linear dynamics, a 2-dimensional Rayleigh-Benard convection model was developed to simulate the convection, Lorenz equations of LNG convection were deduced from conservation equations, and the Runge-Kutta method was used to solve the equations. The results showed that when = 1.33, 106 < < 1470, chaos was obtained, which meant that the velocity field and the temperature field were highly unsteady. In addition, the influence of temperature and scale factor on the solutions and the corresponding range of parameters were studied. The results revealed that the chaos in LNG convection resulted from the interaction of buoyancy and viscid forces. A small quantity of heat impacting the storage tank would lead to a strong and unstable convection of LNG in the main stream region.

关键词: Runge-Kutta     non-linear     corresponding     temperature     addition    

Spatial distribution of ecological security status assessment of West-Liaohe River based on geographic information system

WANG Geng, WU Wei

《环境科学与工程前沿(英文)》 2007年 第1卷 第4期   页码 471-476 doi: 10.1007/s11783-007-0075-4

摘要: Eco-security assessment is a hot research area in resource and environmental science, which involves data with much spatial, non-linear, and random features. Geographic information system (GIS), as a useful tool to analyze and mana

关键词: environmental     Eco-security assessment     resource     Geographic information     non-linear    

Linear and nonlinear elastic analysis of closely spaced strip foundations using Pasternak model

Priyanka GHOSH, S. RAJESH, J. SAI CHAND

《结构与土木工程前沿(英文)》 2017年 第11卷 第2期   页码 228-243 doi: 10.1007/s11709-016-0370-x

摘要: In this study, an attempt is made to determine the interaction effect of two closely spaced strip footings using Pasternak model. The study considers small strain problem and has been performed using linear as well as nonlinear elastic analysis to determine the interaction effect of two nearby strip footings. The hyperbolic stress-strain relationship has been considered for the nonlinear elastic analysis. The linear elastic analysis has been carried out by deriving the equations for the interference effect of the footings in the framework of Pasternak model equation; whereas, the nonlinear elastic analysis has been performed using the finite difference method to solve the second order nonlinear differential equation evolved from Pasternak model with proper boundary conditions. Results obtained from the linear and the nonlinear elastic analysis are presented in terms of non-dimensional interaction factors by varying different parameters like width of the foundation, load on the foundation and the depth of the rigid base. Results are suitably compared with the existing values in the literature.

关键词: bearing capacity     linear and non-linear elasticity     foundation     interaction effect     numerical modeling     Pasternak model    

Optimal localization of complex surfaces in CAD-based inspection

XU Jinting, LIU Weijun, SUN Yuwen

《机械工程前沿(英文)》 2008年 第3卷 第4期   页码 426-433 doi: 10.1007/s11465-008-0068-4

摘要: Complex surface inspection requires the optimal localization of the measured surface related to the design surface so that the two surfaces can be compared in a common coordinate frame. This paper presents a new technique for solving the localization problem. The basic approach consists of two steps: 1) rough localization of the measured points to the design surface based on curvature features, which can produce a good initial estimate for the optimal localization; 2) fine localization based on the least-square principle so that the deviation between the measured surface and the design surface is minimized. To efficiently compute the closest points on the design surface of the measured points, a novel method is proposed. Since this approach does not involve an iterative process of solving non-linear equations for the closest points, it is more convenient and robust. The typical complex surface is used to test the developed algorithm. Analysis and comparison of experimental results demonstrate the validity and applicability of the algorithm.

关键词: deviation     comparison     non-linear     localization     inspection    

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

《结构与土木工程前沿(英文)》 2022年 第16卷 第12期   页码 1565-1580 doi: 10.1007/s11709-022-0867-4

摘要: This study proposes a shape optimization method for K6 aluminum alloy spherical reticulated shells with gusset joints, considering geometric, material, and joint stiffness nonlinearities. The optimization procedure adopts a genetic algorithm in which the elastoplastic non-linear buckling load is selected as the objective function to be maximized. By confinement of the adjustment range of the controlling points, optimization results have enabled a path toward achieving a larger elastoplastic non-linear buckling load without changing the macroscopic shape of the structure. A numerical example is provided to demonstrate the effectiveness of the proposed method. In addition, the variation in structural performance during optimization is illustrated. Through parametric analysis, practical design tables containing the parameters of the optimized shape are obtained for aluminum alloy spherical shells with common geometric parameters. To explore the effect of material nonlinearity, the optimal shapes obtained based on considering and not considering material non-linear objective functions, the elastoplastic and elastic non-linear buckling loads, are compared.

关键词: shape optimization     aluminum alloy     spherical reticulated shell     non-linear buckling     material nonlinearity     genetic algorithm    

重复压裂高效暂堵剂研制与评价

闫治涛

《中国工程科学》 2012年 第14卷 第4期   页码 20-25

摘要:

根据中浅层油气藏重复压裂暂堵老缝压开新缝,以及压裂过程控制裂缝转向的需要,研制了一种新型的高效缝内暂堵剂,并通过实验评价了暂堵剂产生暂堵的机理,包括暂堵材料粒度、注入流量和浓度等对暂堵效果的影响;并对暂堵后裂缝延伸及压后返排对气井生产的影响进行了非线性有限元数值分析,研究表明该暂堵剂具有良好的暂堵效果,对气井无二次污染,并在重复压裂中对气层起到了很好的保护作用。

关键词: 重复压裂     暂堵剂     裂缝转向     非线性有限元分析     气层保护    

Integrated control strategies for railway vehicles with independently-driven wheel motors

FENG Jinzhi, LI Jun, Goodall R. M.

《机械工程前沿(英文)》 2008年 第3卷 第3期   页码 239-250 doi: 10.1007/s11465-008-0053-y

摘要: This paper studies the development of integrated control strategies for railway vehicles with independently-driven wheel motors. First, a non-linear vehicle dynamic model and motor drive strategy are presented, which are followed by an investigation of the integrated control of stabilization, steering, and traction for the vehicle. Meanwhile a reformulated Kalman filter is developed and applied to estimate the required feedback by the control system. Finally, the effectiveness and practicality of the proposed integrated controller are examined and assessed by real-time simulation based on host-target computer technology provided by Matlab/Simulink.

关键词: development     independently-driven     non-linear     stabilization     reformulated    

Seismic progressive-failure analysis of tall steel structures under beam-removal scenarios

Behrouz BEHNAM, Fahimeh SHOJAEI, Hamid Reza RONAGH

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 904-917 doi: 10.1007/s11709-019-0525-7

摘要: Investigating progressive collapse of tall structures under beam removal scenarios after earthquake is a complex subject because the earthquake damage acts as an initial condition for the subsequent scenario. An investigation is performed here on a 10 story steel moment resisting structure designed to meet the life safety level of performance when different beam removal scenarios after earthquake are considered. To this end, the structure is first subjected to the design earthquake simulated by Tabas earthquake acceleration. The beam removal scenarios are then considered at different locations assuming that both ends connections of the beam to columns are simultaneously detached from the columns; thus the removed beam falls on the underneath floor with an impact. This imposes considerable loads to the structure leading to a progressive collapse in all the scenarios considered. The results also show that the upper stories are much more vulnerable under such scenarios than the lower stories. Hence, more attention shall be paid to the beam-to-column connections of the upper stories during the process of design and construction.

关键词: progressive collapse     tall steel moment-resisting frames     non-linear dynamic analysis     beam-removal scenario     impact    

Aseismic smart building isolation systems under multi-level earthquake excitations: Part I, conceptual design and nonlinear analysis

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

《结构与土木工程前沿(英文)》 2015年 第9卷 第3期   页码 286-296 doi: 10.1007/s11709-015-0307-9

摘要: As a novel structural control strategy, tuned mass damper (TMD) inspired passive and semi-active smart building isolation systems are suggested to reduce structural response and thus mitigate structural damage due to earthquake excitations. The isolated structure’s upper stories can be utilized as a large scaled TMD, and the isolation layer, as a core design point, between the separated upper and lower stories entails the insertion of rubber bearings and (i) viscous dampers (passive) or (ii) resettable devices (semi-active). The seismic performance of the suggested isolation systems are investigated for 12-story reinforced concrete moment resisting frames modeled as “10+ 2” stories and “8+ 4” stories. Passive viscous damper or semi-active resettable devices are parametrically evaluated through the optimal design principle of a large mass ratio TMD. Statistical performance metrics are presented for 30 earthquake records from the three suites of the SAC project. Based on nonlinear structural models, including P-delta effects and modified Takeda hysteresis, the inelastic time history analyses are conducted to compute the seismic performances across a wide range of seismic hazard intensities. Results show that semi-active smart building isolation systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions in comparison to uncontrolled case and passive solution.

关键词: tuned mass damper     smart building isolation     resettable device     non-linear     statistical assessment    

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    

A new method for boring of non-circular holes

ZHANG Kai, HU De-jin

《机械工程前沿(英文)》 2006年 第1卷 第4期   页码 456-460 doi: 10.1007/s11465-006-0058-3

摘要: A revolving electromagnetic actuation mechanism composed of an electromagnetic stator and an electromagnetic rotor has been developed for boring non-circular holes. The main component of the rotor is a flexure-hinged based flexible body. There are four pole-pair coils in the stator supplying actuation currents. The micro-displacement between the stator and rotor can be controlled by changing the currents applied in the pole-pair coils. Through linearization of the actuation force near the static action point, a linear relationship between the control current and the actuation force was established, and the synchronizing control method of the electromagnetic actuation mechanism is presented here. With two-factor analysis of the linearization error of the actuation force, the influences of control current and micro-displacement to the linearization error of the actuation force were studied. Then, the principle for designing the basic parameters of the magnetic actuation mechanism is put forward. The calibration of the mechanism indicates that the relationship between the micro-displacement of the rotor and the control current has linear characteristics in the required micro-displacement range. Simulation tests show that the turning radius of the rotor changes with the control current. The proposed mechanism can feasibly supply a controllable micro displacement to the boring bar.

关键词: electromagnetic actuation     control method     displacement     flexible body     revolving electromagnetic    

工程网络计划的LR型模糊系数线性规划方法

高朋,冯俊文

《中国工程科学》 2009年 第11卷 第2期   页码 70-74

摘要:

工程网络计划的基础是对各工序持续时间的估计,而导致工序工期不确定性的因素不仅具有随机性,通常也具有模糊性。文章提出一种具有LR型模糊数的线性规划模型,解决了工程网络计划的时间参数 估计和关键路径识别问题,并通过引入λ截集来充分描述决策者在不同情形下对工序工期估计的可信程度。 最后给出一实例详细说明了该方法的应用过程及有效性。

关键词: 工程网络计划     模糊线性规划     工序    

标题 作者 时间 类型 操作

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

期刊论文

Recent development of vibration utilization engineering

WEN Bangchun

期刊论文

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

期刊论文

Chaotic behavior of LNG after stratification in main stream region of storage tank

WANG Jingjing, MA Xiaoqian

期刊论文

Spatial distribution of ecological security status assessment of West-Liaohe River based on geographic information system

WANG Geng, WU Wei

期刊论文

Linear and nonlinear elastic analysis of closely spaced strip foundations using Pasternak model

Priyanka GHOSH, S. RAJESH, J. SAI CHAND

期刊论文

Optimal localization of complex surfaces in CAD-based inspection

XU Jinting, LIU Weijun, SUN Yuwen

期刊论文

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

期刊论文

重复压裂高效暂堵剂研制与评价

闫治涛

期刊论文

Integrated control strategies for railway vehicles with independently-driven wheel motors

FENG Jinzhi, LI Jun, Goodall R. M.

期刊论文

Seismic progressive-failure analysis of tall steel structures under beam-removal scenarios

Behrouz BEHNAM, Fahimeh SHOJAEI, Hamid Reza RONAGH

期刊论文

Aseismic smart building isolation systems under multi-level earthquake excitations: Part I, conceptual design and nonlinear analysis

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

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

A new method for boring of non-circular holes

ZHANG Kai, HU De-jin

期刊论文

工程网络计划的LR型模糊系数线性规划方法

高朋,冯俊文

期刊论文