共查询到20条相似文献，搜索用时 31 毫秒
1.
True bond graphs, which use effort and flow variables whose product is power, can in principle be used to describe all types of physical systems. However, many system models do not use power variables and yet can be represented usefully as pseudo bond graphs. Pseudo bond graphs have been used particularly for open systems in which it is convenient to consider control volumes or compartments with boundaries across which mass can flow. In this paper, we show how the bond graph methods used for conductive and convective heat transfer can be generalized to account for diffusion, convection, and accumulation of a variety of physical quantities and how pseudo bond graphs can aid in constructing and representing such models. These models are known in mathematical biology as “compartmental models” and it is a main contribution of this paper to show that the same pseudo bond graphs apply to thermofluid and physiological dynamic models. The bond graphs build in some conservation principles automatically and yet have the flexibility to incorporate general multiport laws when necessary. Thus the pseudo bond graphs can exhibit system structure as do other network graphs and are very general in nature. 相似文献
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Bond graphs are an extremely useful modeling procedure for representing the actual energy exchange mechanisms of interacting dynamic systems. Governing state equations are straightforwardly obtained from the bond graph; however, for large structures, a restrictively large number of equations can result. A procedure is developed whereby the original equations are reduced to a form suitable for modal decomposition. The resulting modes are reinterpreted in bond graph form with the resulting model being an extremely accurate system representation while requiring only a fraction of the original number of equations. The procedure is demonstrated through example. 相似文献
3.
Dean Karnopp 《Journal of The Franklin Institute》1978,306(2):165-181
Dynamic systems containing particles and rigid bodies capable of movement in two- or three-dimensions may be represented by equations of motion in several basic forms. In all cases geometric nonlinearities are involved and terms arise in the equations which are difficult to understand and interpret. The equations often conceal the basic structure of the dynamic model of the system since only combinations of parameters and combined effects of various constraints finally appear.In this paper the basic relations for the dynamic elements as well as the transformations among internal forces and velocities are depicted using bond graphs. The energetic structure of the system is thus exhibited in multiport form. This aids in the exploration of alternative equation formulation and in understanding of the assumptions involved in any particular equation set. Further, a bond graph model is easily coupled with nonmechanical dynamic models through force or motion generators. 相似文献
4.
Donald L. Margolis 《Journal of The Franklin Institute》1980,310(2):107-117
Bond graphs are used to construct finite mode representations of inherently distributed systems. These systems are, perhaps, only part of an overall dynamic system. The “causal” information provided by the bond graph permits the derivation of an automatable algorithm which produces the state equations as well as all output variables associated with the finite modes. The procedure requires only the a priori knowledge of modal masses, frequencies, and associated mode shapes for general boundary conditions of the distributed parts of the system. Thus, the algorithm is applicable to any multidimensional distributed system which is representable by normal modes. 相似文献
5.
Bond graphs have proven to be useful in modeling a wide variety of physical systems where multiports are needed to represent coupling phenomena. Here we show the relationship between bond graphs and more conventional notations utilizing connection N-ports and system graphs. This provides a rigorous foundation for bond graph manipulations and highlights certain difficulties with sign conventions and casual assignments that arise when junction structure loops are present. 相似文献
6.
H. Cormerais J. Buisson P.Y. Richard C. Morvan 《Journal of The Franklin Institute》2008,345(5):468-488
This paper addresses the modelling and control of switched systems with Boolean inputs. A generalization of Passivity Based Control (PBC) is proposed and fitted to bond graph formalism. The state equations of the equivalent average model are first deduced from the original bond graph using the notion of commutation cells and then interpreted according to Port Controlled Hamiltonian formalism. The whole approach is presented in a formal way. This method is then applied on a multicellular serial converter, which is widespread in power systems and of growing interest. The application of PBC associated to a modelling approach using commutation cells on a non-trivial example shows its efficiency to determine a generic controller, the number of elementary cells being considered as a parameter. 相似文献
7.
Donald L. Margolis 《Journal of The Franklin Institute》1979,308(3):255-268
A procedure is presented whereby the control volume equations for one-dimensional, compressible gas dynamics are cast into first-order, state variable form. These equations are interpreted using causal bond graphs. The resulting bond graph is shown to reduce to the classic I-C chain under acoustic constraints and to a more recently developed model of low speed thermal energy transport subject to associated constraints.Through example it is demonstrated that the control volume bond graph is easily coupled to an overall system model and thus can be digitally simulated as part of the overall nonlinear state space representation. The result is that a very accurate gas dynamic model can be coupled with an overall dynamic system model without requiring a prohibitively large number of equations. 相似文献
8.
Model-based fault detection and isolation (FDI) requires an analytical system model from which fault indicators can be derived by assigning proper computational causalities. Many bond graph (BG) model-based techniques for FDI have been developed in recent past. Furthermore, many other advances have been made in the field of control engineering applications of BG modelling. Supervision systems not only perform FDI, but also take the necessary steps for fault accommodation. Fault accommodation is done either through system reconfiguration or through fault tolerant control (FTC). In this paper, it is shown that bicausal BG modelling proves to be a unified approach for sensor placement from the FDI and FTC viewpoint, identification of hardware redundancies for system reconfiguration, generation of fault indicators, estimation of fault parameters for fault accommodation, inversion of systems and actuator sizing for FTC, etc. It is shown that the use of bicausalled BG helps to integrate many of the recently developed advances made in the field of control engineering into development of complex supervision systems. 相似文献
9.
Previous works have shown the usefulness of bond graphs for modeling and simulation of interacting lumped and distributed systems. Frequently, when damping is included in the model, the overall system is “stiff”, possessing widely disparate characteristic times. This makes simulation difficult and time consuming.Bond graphs are used here to represent the interacting lumped and modal dynamics of a system while treating the damping as an external forcing onto the system. By performing a second modal decomposition, a second bond graph model can be formulated where the damping can now be physically represented. The result is a total system model in which the characteristic times can be controlled through elimination of high frequency modes. 相似文献
10.
机械零部件的安全可靠是机械设计的主要目的之一，由于工程材料性的离散性以及制造、安装误差等因素的影响，使机械零部件的参数具有固有的随机性，因此研究这种机械系统的可靠性问题有十分重要的意义，这种研究可以帮助工程设计人员合理地建立机械系统的安全容限和控制随机参数对机械系统安全的影响．将可靠性设计理论与灵敏度分析方法相结合，讨论了螺旋管簧的可靠性的参数灵敏度分析问题，提出了可靠性灵敏度设计的计算方法，研究了正态分布设计参数的改变对螺旋管簧可靠性的影响，给出了可靠性灵敏度的变化规律，根据编制的相关的实用程序，可以迅速准确地得到螺旋管簧的可靠性灵敏度设计信息，为螺旋管簧的可靠性设计提供了理论依据。 相似文献
11.
H. Atlan R. Panet S. Sidoroff J. Salomon G. Weisbuch 《Journal of The Franklin Institute》1979,308(3):297-308
Bond graphs are used in order to understand the mechanism of interaction of three important and inter-related processes of reticulocyte metabolism: potassium efflux through the cell membrane, ATP metabolism and protein synthesis. Experimental data relative to membrane mediated inhibition of this synthesis by potassium carriers, dicyclohexyl-18-crown-6 and valinomycin, are then fitted to dynamical equations suggested from the bond graphs. 相似文献
12.
Dean Karnopp 《Journal of The Franklin Institute》1977,303(1):85-98
Although no truly linear physical systems exist, linearized system models are very often used in practice to study the dynamics of real systems and components. Here, the relations between the power and energy in a non-linear physical system and the analogous quantities associated with variables representing small deviations from steady-state values are studied. Sometimes a linearized system is energetically similar to the non-linear system from which it was derived, and in other cases, new types of energy elements appear which were not present in the original system. In order to show the structure of the systems, the results are presented in both equation form and in the form of bond graphs which are unique in exhibiting the power and energy structure of system models. 相似文献
13.
This paper presents the optimal regulator for a linear system with state delay and a quadratic criterion. The optimal regulator equations are obtained using the maximum principle. Performance of the obtained optimal regulator is verified in the illustrative example against the best linear regulator available for linear systems without delays. Simulation graphs demonstrating better performance of the obtained optimal regulator are included. The paper then presents a robustification algorithm for the obtained optimal regulator based on integral sliding mode compensation of disturbances. The general principles of the integral sliding mode compensator design are modified to yield the basic control algorithm oriented to time-delay systems, which is then applied to robustify the optimal regulator. As a result, the sliding mode compensating control leading to suppression of the disturbances from the initial time moment is designed. The obtained robust control algorithm is verified by simulations in the illustrative example. 相似文献
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This paper presents the optimal quadratic-Gaussian controller for uncertain stochastic polynomial systems with linear control input and a quadratic criterion over linear observations. The optimal closed-form controller equations are obtained using the separation principle, whose applicability to the considered problem is substantiated. As intermediate results, the paper gives closed-form solutions of the optimal regulator and controller problems for stochastic polynomial systems with linear control input and a quadratic criterion. Performance of the obtained optimal controller is verified in the illustrative example against the conventional quadratic-Gaussian controller that is optimal for stochastic polynomial systems with known parameters. Simulation graphs demonstrating overall performance and computational accuracy of the designed optimal controller are included. 相似文献
16.
[研究目的]战略情报分析主要是由情报专家人工分析为主,在信息系统方面的建设还比较薄弱,文章结合情报分析过程,提出基于孙子情报分析理论构建标签体系,作为信息系统设计实现的一种参考。[研究方法]通过孙子情报分析理论、标签的定义、战略情报分析过程描述了战略情报分析标签体系的构建及其作用,提出了以顶层标签作为切入点构建战略问题分析模型,以及战略情报分析计算模型。[研究结论]标签体系应用广泛,以孙子情报分析理论的“道、天、地、将、法”为基础构建战略情报分析标签体系,进行战略问题分析建模与计算,对战略情报分析研究和相关信息系统建设具有一定的指导意义。 相似文献
17.
钱学森作为享誉中外的科学巨匠,其卓绝的学术功绩和思想光辉在学术界掀起探究热潮。在钱学森百岁诞辰之际,我们从文献计量学的角度历数他给我们留下的思想财富,试图展示出一个较为完整的钱学森科学思想体系。共词分析的结果表明, 他在“系统科学与工程”、“思维科学”、“大农业经济”、“科学学”、“技术科学”、“城市科学”和“人才培养”方面的思想尤为后人关注,其中,“系统科学思想”作为核心思想始终贯穿于其中,形成了独具特色的钱学森科学思想体系。 相似文献
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This paper presents the optimal regulator for a linear system with time delay in control input and a quadratic cost function. The optimal regulator equations are obtained using the duality principle, which is applied to the optimal filter for linear systems with time delay in observations, and then proved using the maximum principle. Performance of the obtained optimal regulator is verified in the illustrative example against the best linear regulator available for linear systems without delays. Simulation graphs and comparison tables demonstrating better performance of the obtained optimal regulator are included. 相似文献
20.
Modelling of switching systems in bond graphs using the concept of switched power junctions 总被引：1，自引：0，他引：1
Modelling of switching systems using bond graph is a research issue. There have been many proposals in this context. However, there are many issues that need consideration. This paper proposes the concept of switched power junctions that is a generalisation of the conventional junction concept in bond graph modelling. This approach removes most of the difficulties associated with other methodologies. This method ensures that causality remains invariant during mode switching thus keeping the state vector and its dimension time invariant. Further, the switched power junction displays all feasible system modes at the same time on the same graph. This concept is further illustrated through simulation using examples of switching systems in the electrical domain. 相似文献