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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    

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    

Scaled boundary finite element method with exact defining curves for two-dimensional linear multi-field

Jaroon RUNGAMORNRAT, Chung Nguyen VAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 201-214 doi: 10.1007/s11709-018-0488-0

摘要: This paper presents an efficient and accurate numerical technique based upon the scaled boundary finite element method for the analysis of two-dimensional, linear, second-order, boundary value problems with a domain completely described by a circular defining curve. The scaled boundary finite element formulation is established in a general framework allowing single-field and multi-field problems, bounded and unbounded bodies, distributed body source, and general boundary conditions to be treated in a unified fashion. The conventional polar coordinates together with a properly selected scaling center are utilized to achieve the exact description of the circular defining curve, exact geometry of the domain, and exact spatial differential operators. Standard finite element shape functions are employed in the discretization of both trial and test functions in the circumferential direction and the resulting eigenproblem is solved by a selected efficient algorithm. The computational performance of the implemented procedure is then fully investigated for various scenarios to demonstrate the accuracy in comparison with standard linear elements.

关键词: multi-field problems     defining curve     exact geometry     general boundary conditions     SBFEM    

Optical performance analysis of an innovative linear focus secondary trough solar concentrating system

Xiliang ZHANG, Zhiying CUI, Jianhan ZHANG, Fengwu BAI, Zhifeng WANG

《能源前沿(英文)》 2019年 第13卷 第3期   页码 590-596 doi: 10.1007/s11708-018-0602-y

摘要: The parabolic trough solar concentrating system has been well developed and widely used in commercial solar thermal power plants. However, the conventional system has its drawbacks when connecting receiver tube parts and enhancing the concentration ratio. To overcome those inherent disadvantages, in this paper, an innovative concept of linear focus secondary trough concentrating system was proposed, which consists of a fixed parabolic trough concentrator, one or more heliostats, and a fixed tube receiver. The proposed system not only avoids the end loss and connection problem on the receiver during the tracking process but also opens up the possibility to increase the concentration ratio by enlarging aperture. The design scheme of the proposed system was elaborated in detail in this paper. Besides, the optical performance of the semi and the whole secondary solar trough concentrator was evaluated by using the ray tracing method. This innovative solar concentrating system shows a high application value as a solar energy experimental device.

关键词: secondary parabolic trough solar concentrator     ray tracing method     linear focus     concentration ratio     optical performance    

Design and modeling of a free-piston engine generator

《能源前沿(英文)》 2023年 第17卷 第6期   页码 811-821 doi: 10.1007/s11708-022-0848-2

摘要: Free-piston engine generators (FPEGs) can be applied as decarbonized range extenders for electric vehicles because of their high thermal efficiency, low friction loss, and ultimate fuel flexibility. In this paper, a parameter-decoupling approach is proposed to model the design of an FPEG. The parameter-decoupling approach first divides the FPEG into three parts: a two-stroke engine, an integrated scavenging pump, and a linear permanent magnet synchronous machine (LPMSM). Then, each of these is designed according to predefined specifications and performance targets. Using this decoupling approach, a numerical model of the FPEG, including the three aforementioned parts, was developed. Empirical equations were adopted to design the engine and scavenging pump, while special considerations were applied for the LPMSM. A finite element model with a multi-objective genetic algorithm was adopted for its design. The finite element model results were fed back to the numerical model to update the LPMSM with increased fidelity. The designed FPEG produced 10.2 kW of electric power with an overall system efficiency of 38.5% in a stable manner. The model provides a solid foundation for the manufacturing of related FPEG prototypes.

关键词: free-piston engine generator     linear permanent magnet synchronous machine     system design     numerical model     finite element method    

Design and analysis of linear oscillating motor for linear pump application-magnetic field, dynamics

Zongxia JIAO,Tianyi WANG,Liang YAN

《机械工程前沿(英文)》 2016年 第11卷 第4期   页码 351-362 doi: 10.1007/s11465-016-0407-9

摘要:

A linear oscillating motor is an electromagnetic actuator that can achieve short-stroke reciprocating movement directly without auxiliary transmission mechanisms. It has been widely used in linear pump applications as the source of power and motion. However, because of the demand of high power density in a linear actuation system, the performance of linear oscillating motors has been the focus of studies and deserves further research for high power density. In this paper, a general framework of linear oscillating motor design and optimization is addressed in detail, including the electromagnetic, dynamics, and thermal aspects. First, the electromagnetic and dynamics characteristics are modeled to reveal the principle for optimization. Then, optimization and analysis on magnetic structure, resonant system, and thermal features are conducted, which provide the foundation for prototype development. Finally, experimental results are provided for validation. As a whole, this process offers complete guidance for high power density linear oscillating motors in linear pump applications.

关键词: linear oscillating motor     linear pump     magnetic field     motor optimization    

A method to predict cooling load of large commercial buildings based on weather forecast and internal

Junbao JIA,Jincheng XING,Jihong LING,Ren PENG

《能源前沿(英文)》 2016年 第10卷 第4期   页码 459-465 doi: 10.1007/s11708-016-0424-8

摘要: Considering the fact that customers of large commercial buildings have the characteristics of the higher density and randomness, this paper presented an air-conditioning cooling load prediction method based on weather forecast and internal occupancy density. The multiple linear feedback regression model was applied to predict, with precision, the air conditioning cooling load. Case analysis showed that the largest mean relative error of hourly and the daily predicting cooling load maximum were 18.1% and 5.14%, respectively.

关键词: commercial building     load prediction     multiple linear regression    

General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 15-24 doi: 10.1007/s11465-009-0015-z

摘要: The typical time series models such as ARMA, AR, and MA are founded on the normality and stationarity of a system and expressed by a linear difference equation; therefore, they are strictly limited to the linear system. However, some nonlinear factors are within the practical system; thus, it is difficult to fit the model for real systems with the above models. This paper proposes a general expression for linear and nonlinear auto-regressive time series models (GNAR). With the gradient optimization method and modified AIC information criteria integrated with the prediction error, the parameter estimation and order determination are achieved. The model simulation and experiments show that the GNAR model can accurately approximate to the dynamic characteristics of the most nonlinear models applied in academics and engineering. The modeling and prediction accuracy of the GNAR model is superior to the classical time series models. The proposed GNAR model is flexible and effective.

关键词: linear and nonlinear     autoregressive model     system identification     time series analysis    

Multiple linear regression, artificial neural network, and fuzzy logic prediction of 28 days compressive

Faezehossadat KHADEMI,Mahmoud AKBARI,Sayed Mohammadmehdi JAMAL,Mehdi NIKOO

《结构与土木工程前沿(英文)》 2017年 第11卷 第1期   页码 90-99 doi: 10.1007/s11709-016-0363-9

摘要: Evaluating the in situ concrete compressive strength by means of cores cut from hardened concrete is acknowledged as the most ordinary method, however, it is very difficult to predict the compressive strength of concrete since it is affected by many factors such as different mix designs, methods of mixing, curing conditions, compaction, etc. In this paper, considering the experimental results, three different models of multiple linear regression model (MLR), artificial neural network (ANN), and adaptive neuro-fuzzy inference system (ANFIS) are established, trained, and tested within the Matlab programming environment for predicting the 28 days compressive strength of concrete with 173 different mix designs. Finally, these three models are compared with each other and resulted in the fact that ANN and ANFIS models enables us to reliably evaluate the compressive strength of concrete with different mix designs, however, multiple linear regression model is not feasible enough in this area because of nonlinear relationship between the concrete mix parameters. Finally, the sensitivity analysis (SA) for two different sets of parameters on the concrete compressive strength prediction are carried out.

关键词: concrete     28 days compressive strength     multiple linear regression     artificial neural network     ANFIS     sensitivity analysis (SA)    

System construction of a four-side primary permanent-magnet linear motor drive mechanical press

Jintao LIANG, Zhengfeng MING, Peida LI

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 600-609 doi: 10.1007/s11465-020-0597-z

摘要: A primary permanent-magnet linear motor (PPMLM) has a robust secondary structure and high force density and is appropriate for direct-drive mechanical press. The structure of a four-side PPMLM drive press is presented based on our previous research. The entire press control system is constructed to realize various flexible forming processes. The control system scheme is determined in accordance with the mathematical model of PPMLM, and active disturbance rejection control is implemented in the servo controller. Field-circuit coupling simulation is applied to estimate the system’s performance. Then, a press prototype with 6 kN nominal force is fabricated, and the hardware platform of the control system is constructed for experimental study. Punch strokes with 0.06 m displacement are implemented at trapezoidal speeds of 0.1 and 0.2 m/s; the dynamic position tracking errors are less than 0.45 and 0.82 mm, respectively. Afterward, continuous reciprocating strokes are performed, and the positioning errors at the bottom dead center are less than 0.015 mm. Complex pulse trajectories are also achieved. The proposed PPMLM drive press exhibits a fast dynamic response and favorable tracking precision and is suitable for various forming processes.

关键词: mechanical press     direct drive     primary permanent-magnet linear motor (PPMLM)     servo system     active disturbance rejection control (ADRC)     prototype experiment    

Model reduction techniques for dynamics analysis of ultra-precision linear stage

Xuedong CHEN, Zhixin LI

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 64-70 doi: 10.1007/s11465-009-0009-x

摘要: Spring-damping elements are used to simplify the internal interaction in the proposed finite element (FE) model of an ultra-precision linear stage. The dynamics behavior is studied. The comparison between mode shapes from the eigenvalue analysis shows that the components, except the translator, can represent system dynamics characteristics. A reduction approach is used to simplify the system in a dynamic studied. There is little difference between the vibration mode and the response analysis. The experimental modal analysis proves the validity of the reduction approach, which can be generalized to the development and dynamics characteristic study of a complex system model to obviously save computational resource.

关键词: dynamics analysis     air-bearing     linear stage     reduction    

A linear quadratic regulator control of a stand-alone PEM fuel cell power plant

Amar BENAISSA, Boualaga RABHI, Ammar MOUSSI, Dahmani AISSA

《能源前沿(英文)》 2014年 第8卷 第1期   页码 62-72 doi: 10.1007/s11708-013-0291-5

摘要: This paper introduces a technique based on linear quadratic regulator (LQR) to control the output voltage at the load point versus load variation from a stand-alone proton exchange membrane (PEM) fuel cell power plant (FCPP) for a group housing use. The controller modifies the optimal gains by minimizing a cost function, and the phase angle of the AC output voltage to control the active and reactive power output from an FCPP to match the terminal load. The control actions are based on feedback signals from the terminal load, output voltage and fuel cell feedback current. The topology chosen for the simulation consists of a 45 kW proton exchange membrane fuel cell (PEMFC), boost type DC/DC converter, a three-phase DC/AC inverter followed by an LC filter. Simulation results show that the proposed control strategy operated at low commutation frequency (2 kHz) offers good performances versus load variations with low total harmonic distortions (THD) , which is very useful for high power applications.

关键词: modeling of proton exchange membrane fuel cell (PEMFC)     controlling of PEMFC     linear quadratic regulator (LQR)     DC/DC converter     DC/AC inverter    

Load shedding scheme for the two-area system with linear quadratic regulator

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

《能源前沿(英文)》 2013年 第7卷 第1期   页码 90-102 doi: 10.1007/s11708-012-0224-8

摘要: The power system is prone to many emergency conditions which may lead to emergency state of operation with decay in the system frequency. The dramatic change in the frequency can result in cascaded failure of the system. In order to avoid power system collapse, load shedding (LS) schemes are adopted with the optimal amount of load shed. This paper proposed a methodology in a two-area thermal-thermal system for finding the required amount of load to be shed for setting the frequency of the system within minimum allowable limits. The LS steps have been obtained based on the rate of change of frequency with the increase in load in steps. A systematic study has been conducted for three scenarios: the scheme with a conventional integral controller; the scheme with a linear quadratic regulator (LQR); and the scheme with an LQR and superconducting magnetic energy storage devices (SMES). A comparison of the results has been presented on the two-area system.

关键词: critical load     frequency response     load shedding (LS)     multi-area system     rate of change of frequency     linear quadratic regulator (LQR)     superconducting magnetic energy storage devices (SMES)    

Mechatronic design of a novel linear compliant positioning stage with large travel range and high out-of-plane

Hua LIU, Xin XIE, Ruoyu TAN, Lianchao ZHANG, Dapeng FAN

《机械工程前沿(英文)》 2017年 第12卷 第2期   页码 265-278 doi: 10.1007/s11465-017-0453-y

摘要:

Most of the XY positioning stages proposed in previous studies are mainly designed by considering only a single performance indicator of the stage. As a result, the other performance indicators are relatively weak. In this study, a 2-degree-of-freedom linear compliant positioning stage (LCPS) is developed by mechatronic design to balance the interacting performance indicators and realize the desired positioning stage. The key parameters and the coupling of the structure and actuators are completely considered in the design. The LCPS consists of four voice coil motors (VCMs), which are conformally designed for compactness, and six spatial leaf spring parallelograms. These parallelograms are serially connected for a large travel range and a high out-of-plane payload capacity. The mechatronic model is established by matrix structural analysis for structural modeling and by Kirchhoff’s law for the VCMs. The sensitivities of the key parameters are analyzed, and the design parameters are subsequently determined. The analytical model of the stage is confirmed by experiments. The stage has a travel range of 4.4 mm× 7.0 mm and a 0.16% area ratio of workspace to the outer dimension of the stage. The values of these performance indicators are greater than those of any existing stage reported in the literature. The closed-loop bandwidth is 9.5 Hz in both working directions. The stage can track a circular trajectory with a radius of 1.5 mm, with 40 mm error and a resolution of lower than 3 mm. The results of payload tests indicate that the stage has at least 20 kg out-of-plane payload capacity.

关键词: mechatronic design     linear compliant positioning stage     large travel range     high out-of-plane payload capacity     spatial parallelogram     voice coil motor     sensitivity analysis    

Development of a masticatory robot using a novel cable-driven linear actuator with bidirectional motion

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0687-1

摘要: Masticatory robots are an effective in vitro performance testing device for dental material and mandibular prostheses. A cable-driven linear actuator (CDLA) capable of bidirectional motion is proposed in this study to design a masticatory robot that can achieve increasingly human-like chewing motion. The CDLA presents remarkable advantages, such as lightweight and high stiffness structure, in using cable amplification and pulley systems. This work also exploits the proposed CDLA and designs a masticatory robot called Southeast University masticatory robot (SMAR) to solve existing problems, such as bulky driving linkage and position change of the muscle’s origin. Stiffness analysis and performance experiment validate the CDLA’s efficiency, with its stiffness reaching 1379.6 N/mm (number of cable parts n = 4), which is 21.4 times the input wire stiffness. Accordingly, the CDLA’s force transmission efficiencies in two directions are 84.5% and 85.9%. Chewing experiments are carried out on the developed masticatory robot to verify whether the CDLA can help SMAR achieve a natural human-like chewing motion and sufficient chewing forces for potential applications in performance tests of dental materials or prostheses.

关键词: masticatory robot     cable-driven     linear actuator     parallel robot     stiffness analysis    

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

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

Scaled boundary finite element method with exact defining curves for two-dimensional linear multi-field

Jaroon RUNGAMORNRAT, Chung Nguyen VAN

期刊论文

Optical performance analysis of an innovative linear focus secondary trough solar concentrating system

Xiliang ZHANG, Zhiying CUI, Jianhan ZHANG, Fengwu BAI, Zhifeng WANG

期刊论文

Design and modeling of a free-piston engine generator

期刊论文

Design and analysis of linear oscillating motor for linear pump application-magnetic field, dynamics

Zongxia JIAO,Tianyi WANG,Liang YAN

期刊论文

A method to predict cooling load of large commercial buildings based on weather forecast and internal

Junbao JIA,Jincheng XING,Jihong LING,Ren PENG

期刊论文

General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

期刊论文

Multiple linear regression, artificial neural network, and fuzzy logic prediction of 28 days compressive

Faezehossadat KHADEMI,Mahmoud AKBARI,Sayed Mohammadmehdi JAMAL,Mehdi NIKOO

期刊论文

System construction of a four-side primary permanent-magnet linear motor drive mechanical press

Jintao LIANG, Zhengfeng MING, Peida LI

期刊论文

Model reduction techniques for dynamics analysis of ultra-precision linear stage

Xuedong CHEN, Zhixin LI

期刊论文

A linear quadratic regulator control of a stand-alone PEM fuel cell power plant

Amar BENAISSA, Boualaga RABHI, Ammar MOUSSI, Dahmani AISSA

期刊论文

Load shedding scheme for the two-area system with linear quadratic regulator

D. TYAGI, Ashwani KUMAR, Saurabh CHANANA

期刊论文

Mechatronic design of a novel linear compliant positioning stage with large travel range and high out-of-plane

Hua LIU, Xin XIE, Ruoyu TAN, Lianchao ZHANG, Dapeng FAN

期刊论文

Development of a masticatory robot using a novel cable-driven linear actuator with bidirectional motion

期刊论文