Estimation of non-uniquely identifiable parameters via exhaustive modeling and membership set theory

A new methodology for estimating parameters that are not structurally globally identifiable is presented. The set of all the models which have exactly the same input–output behavior is first generated. The influence of the measurement noise and structural error is then taken into account by assuming that upper and lower bounds of the acceptable output error are available. The set of all the models compatible with this hypothesis is characterized, and ranges for the possible values of the estimated parameters are provided. An example is treated involving two real–life model structures used to describe the behavior of an isotopic tracer in a reactor producing methane from carbon monoxide and hydrogen.     

Integrated modeling and analysis of dynamics for electric vehicle powertrains

Powertrain of an electric vehicle (EV) is a compound system with an electrical sub-system, such as batteries, inverters, and electrical motors, as well as a mechanical sub-system, including transmissions, differential, and wheels. Since the electrical systems directly affect the vehicle driving performance and dynamics of an EV, integrated modeling considering both the mechanical and electrical systems is essential to assess ultimate kinetic and dynamic characteristics of an EV in terms of input electrical quantities. In this paper, an entire analytic model for the powertrain of EVs is developed to describe EV dynamics with respect to electrical signals, in consideration of both mechanical and electrical systems. Theoretical models based on mathematical expressions, combining the mechanical power system and the electrical power systems, are derived for predicting the final vehicle driving performance as a function of electrical quantities. In addition, a Matlab model of an EV is developed to verify the derived mathematical analysis model. Based on the theoretical model of the powertrain, a variety of relationships between electrical quantities and vehicle dynamics, such as velocity, acceleration, and forces of the EVs, are finally investigated and analyzed.     

Integration methodology for feature-based modeling and recognition

This paper presents an integration method that constructs a feature model either by inserting new features or by recognizing features from an existing geometric model. This integration is made possible by keeping a feature model data structure that is identical whether constructed by feature insertion or recognition. This approach overcomes the representational mismatch between the procedural feature-based modeling framework and the feature recognition framework. The integrated framework has been implemented as a CADCAM system for mould die manufacturing that can interactively modify the geometric model by deleting recognized features.     

An efficient methodology for modeling complex computer codes with Gaussian processes

Complex computer codes are often too time expensive to be directly used to perform uncertainty propagation studies, global sensitivity analysis or to solve optimization problems. A well known and widely used method to circumvent this inconvenience consists in replacing the complex computer code by a reduced model, called a metamodel, or a response surface that represents the computer code and requires acceptable calculation time. One particular class of metamodels is studied: the Gaussian process model that is characterized by its mean and covariance functions. A specific estimation procedure is developed to adjust a Gaussian process model in complex cases (non-linear relations, highly dispersed or discontinuous output, high-dimensional input, inadequate sampling designs, etc.). The efficiency of this algorithm is compared to the efficiency of other existing algorithms on an analytical test case. The proposed methodology is also illustrated for the case of a complex hydrogeological computer code, simulating radionuclide transport in groundwater.     

A methodology for solving problems: problem modeling and heuristicgeneration

A methodology is given for modeling a problem and solving it using the A* algorithm. The heuristic used for A* is mechanically generated from the simplified problem, which is derived by relaxing each of the predicate formulas describing the rules and the goal state of the problem. The generated heuristic satisfies the conditions of admissibility and monotonicity. The methodology is applicable for solving general problems. The overall procedure for this methodology is illustrated by four well-known problems, namely, the eight-puzzle problem, the traveling salesman problem, the robot planning problem, and the consistent labeling problem. The values of the heuristics generated by this procedure are compared to the corresponding values of problem-oriented heuristics reported in the literature     

A methodology and model for the pull-in parameters of electrostaticactuators

This paper presents a generalized model for the pull-in phenomenon in electrostatic actuators with a single input, either charge or voltage. The pull-in phenomenon of a general electrostatic actuator with a single input is represented by an algebraic equation referred to as the pull-in equation. This equation directly yields the pull-in parameters, namely, the pull-in voltage or pull-in charge and the pull-in displacement. The model presented here permits the analysis of a wide range of cases, including nonlinear mechanical effects as well as various nonlinear, nonideal, and parasitic electrical effects. In some of the cases, an analytic solution is derived, which provides physical insight into how the pull-in parameters depend upon the design and properties of the actuator. The pull-in equation can also yield rapid numerical solutions, allowing interactive and optimal design. The model is then utilized to analyze analytically the case of a Duffing spring, previously analyzed numerically by Hung and Senturia, and captures the variations of the pull-in parameters in the continuum between a perfectly linear spring and a cubic spring. Several other case studies are described and analyzed using the pull-in equation, including parallel-plate and tilted-plate (torsion) actuators taking into account the fringing field capacitance, feedback and parasitic capacitance, trapped charges, an external force, and large displacements     

A multi-agent methodology for multi-level modeling of mechatronic systems

Mechatronic design aims to integrate the models developed during the mechatronic design process, in order to be able to optimize the overall mechatronic system performance. A lot of work has been done in the last few years by researchers and software developers to achieve this objective. However, the level of integration does not yet meet the purposes of mechatronic system designers, particularly when dealing with modeling changes. Therefore, new methodologies are required to manage the multi-view complexity of mechatronic design. In this paper, we propose a multi-agent methodology for the multi-abstraction modeling issue of mechatronic systems. The major contribution deals with proposing a new method for the decomposition of the multi-level design into agents linked with relationships. Each agent is representing an abstraction level and both agent and relationships are managed with rules. By considering an application to a piezoelectric energy harvesting system, we show how we associate agents, rules and inter-level relationships to multi-abstraction modeling. We also show how modeling errors are identified using this approach.     

easyABMS: A domain-expert oriented methodology for agent-based modeling and simulation

Agent-Based Modeling and Simulation (ABMS) has arisen as new approach to effectively support domain experts to cope with the growing complexity of the problems which they have to face and solve. To date, few methodologies are available which can be exploited by domain experts with limited programming expertise to model and subsequently analyze complex systems typical of their application domains. In this paper the easyABMS methodology is proposed to overcome the lack of integrated methodologies able to seamlessly guide domain experts from the analysis of the system under consideration to its modeling and analysis of simulation results. The effectiveness of easyABMS is also experimented through a case study in the logistics domain which concerns the analysis of different policies for managing vehicles used for stacking and moving containers in a transhipment terminal.     

System dynamics modeling for forecasting technological substitution

It is very common, nowadays, to find that a new product or technology is substituting an older one to satisfy a particular consumer need. But with the advancement of technology, there are many instances where a particular product or technology is replacing an older one while at the same time being replaced by a newer one. This relatively new substitution phenonenon can be called a multilevel substitution process. It seems that until now no effort has been directed to study the multilevel substitution cases. Moreover, any forecast made at a given point in time needs to be updated as varying circumstances influence the elements of the forecast. This paper, therefore, presents a systematic methodology for forecasting multilevel technological substitution incorporating various forms of time dependent parameters in an existing trend extrapolation model. The methodology is based on Forrester's “System Dynamics” technique. The developed model makes forecast of the market share as well as the actual size of the market of each of the competing technology or product under various assumptions about the growth of the total joint market based on past trend or future anticipations.     

应用CurveExpert求解生物分子相互作用的化学模型参数

本文首先建立了生物分子相互作用的准一级动力学模型,然后根据由表面等离子共振仪检测蛋白A和球蛋白IgG相互作用所获得的数据,应用CurveExpert软件强大的曲线拟合功能,对蛋白A和球蛋白IgG的结合和解离过程分别进行了曲线拟合分析,获得了它们相互作用的k_a、k_d、K_A和K_D等动力学及亲和力参数。拟合结果表明,蛋白A和球蛋白IgG的相互作用过程符合准一级动力学数学模型,相关性较好,与Origin软件相比,能够自动进行迭代计算,简化了计算步骤和时间。     

响应曲面分析法对青藤碱超临界CO2流体萃取条件的优化

以青风藤药材为原料,在单因素实验研究的基础上,采用Box-Behnken响应曲面分析法对影响青风藤药材中青藤碱超临界CO2萃取得率的关键因素:萃取时间、压力、温度进行了优化,旨在为青藤碱新型、绿色提取分离方法作探讨.根据统计模型进行了工艺参数的优选,以得率为指标,优化后所得青藤碱超临界CO2萃取工艺条件为:萃取压力为27.63 MPa,萃取温度为50.68℃,萃取时间为120.24 mim.该条件下得率为1.372%.验证试验证实了该方程的预测值与试验值之间具有较好的拟合度.     

A methodology and model for the pull-in parameters of magnetostatic actuators

Magnetostatic actuators exhibit bistability similarly to the pull-in phenomena of electrostatic actuators. In this paper a methodology and model for the extraction of the magnetic Pull-In parameters of magnetostatic actuators are derived. The flux-controlled magnetostatic actuator is analyzed based on the energy representation and the magnetomotive force-controlled magnetostatic actuator is analyzed in the thermodynamic potential energy (or co-energy) representation. An algebraic equation, referred to as the magnetic Pull-In equation, for each of the two cases (flux-controlled and magnetomotive force-controlled actuators) is derived. By solving these Pull-In equations either analytically or numerically, the magnetic Pull-In parameters are obtained. Several case studies, covering displacement and torsion magnetic actuators, are presented and analyzed, illustrating the usefulness of the proposed methodology, its relative simplicity as well as the adaptability and practical usage in wide spectrum of magnetic actuators. [1425].     

A stiffness modeling methodology for simulation-driven design of haptic devices

Efficient development and engineering of high performing interactive devices, such as haptic robots for surgical training benefits from model-based and simulation-driven design. The complexity of the design space and the multi-domain and multi-physics character of the behavior of such a product ask for a systematic methodology for creating and validating compact and computationally efficient simulation models to be used in the design process. Modeling the quasi-static stiffness is an important first step before optimizing the mechanical structure, engineering the control system, and performing hardware in the loop tests. The stiffness depends not only on the stiffness of the links, but also on the contact stiffness in each joint. A fine-granular Finite element method (FEM) model, which is the most straightforward approach, cannot, due to the model size and simulation complexity, efficiently be used to address such tasks. In this work, a new methodology for creating an analytical and compact model of the quasi-static stiffness of a haptic device is proposed, which considers the stiffness of actuation systems, flexible links and passive joints. For the modeling of passive joints, a hertzian contact model is introduced for both spherical and universal joints, and a simply supported beam model for universal joints. The validation process is presented as a systematic guideline to evaluate the stiffness parameters both using parametric FEM modeling and physical experiments. Preloading has been used to consider the clearances and possible assembling errors during manufacturing. A modified JP Merlet kinematic structure is used to exemplify the modeling and validation methodology.     

A modeling methodology for collaborative evaluation of future automotive innovations

Software and Systems Modeling - The rapid introduction of innovations plays a major role in automotive industries. Today, once a member of the automotive value chain devises an innovation, the...     

磁流变材料流变学参数与检测方法

磁流变材料的可控流变学特性直接影响磁流变器件性能。在介绍流变学参数的基础上,分析磁流变材料的流变学特性的检测方法、工作原理,阐述相关检测仪器的研究进展;指出了磁流变材料的流变学特性检测技术研究动向。     

An approach for modeling long flexible bodies with application to railroad dynamics

Considering track flexibility in railroad vehicle simulations can lead to improved results. In modeling a railroad vehicle as a multibody system, track flexibility can be incorporated by using the floating frame of reference formulation (FFRF), which describes rail deformations in terms of shape functions defined in the track body frame of reference. However, the FFRF method is subject to two serious shortcomings, namely: it uses unreal track boundary conditions to calculate shape functions and requires a large number of functions to describe deformation. These shortcomings can be circumvented by defining shape functions in the trajectory frame of reference. Based on this notion, a new form of FFRF that can be used to describe the dynamics of long bodies subjected to moving loads (cable cars, zip-lines, elevator guides, pantograph catenary mechanism, etc.) was developed here. The shape functions selected in this work are based on the steady deformation exhibited by a beam on a Winkler foundation under the action of a moving load. However, other sets of shape functions more appropriate for transient dynamics are suggested. The definition of the deformation shape functions in a frame that moves with respect to the flexible body produces new terms in the generalized inertia forces of the flexible track. The proposed approach was applied to an unsuspended wheelset traveling on a tangent track supported on an elastic foundation. The results thus obtained under variable foundation stiffness conditions are discussed and comparisons made with the case of a rigid track. The new approach is also compared with the moving mass problem as solved with the mode superposition method.