Open Systems Formulation and Gaining Insight Using Lagrangian Bond Graphs

2000 ◽  
Author(s):  
Robin C. Redfield
Keyword(s):  
System Dynamics ◽  
Open Systems ◽  
Classical Method ◽  
System Modeling ◽  
Bond Graph ◽  
Small Scale ◽  
Bond Graphs ◽  
Model Modification ◽  
System Equations ◽  
Insight Into

Abstract Models of a small-scale water rocket are developed as an example of open system modeling by both the bond graph approach and a more classical method. One goal of the development is to determine the benefits of the bond graph approach into affording insight into the system dynamics. Both modeling approaches yield equivalent differential equations as they should, while the bond graph approach yields significantly more insight into the system dynamics. If a modeling goal is to simply find the system equations and predict behavior, the classical approach may be more expeditious. If insight and ease of model modification are desired, the bond graph technique is probably the better choice. But then you have to learn it!

The Usage of Bond Graphs Methodology for Mechanical Systems Designing

2015 ◽  
Vol 816 ◽  
pp. 349-356
Author(s):  
Darina Hroncová ◽  
Alexander Gmiterko ◽  
Tomáš Lipták ◽  
František Menda
Keyword(s):  
Classical Method ◽  
Mechanical Systems ◽  
Dc Motor ◽  
Bond Graph ◽  
Bond Graphs ◽  
Introductory Part ◽  
Definition Of ◽  
Simulation Scheme

The article deals with the issue of the usage bond graphs at modeling of mechanical systems. In contrast with the classical method, where the equations for individual components are created first and then on their basis the simulation scheme is derived, here the described method uses the reverse procedure. In the introductory part of article the bond graph notation is defined and next basic types of multi-ports are explained. The last part consists of definition of port and power bond between ports that are explained on example of DC motor with separate excitation.

Physical Modeling With Eulerian Frames and Bond Graphs

1988 ◽  
Vol 110 (2) ◽  
pp. 182-188 ◽  
Author(s):  
J. J. Beaman ◽  
P. C. Breedveld
Keyword(s):  
Physical Modeling ◽  
Ad Hoc ◽  
Open Systems ◽  
Bond Graph ◽  
Bond Graphs ◽  
Graph Topology

In this paper it is shown that open systems, in which matter can enter and leave, are not incompatible with bond graph topology, as commonly reported. Effective modeling of these systems requires that attention be paid to the convective coupling between systems and environment which exchange matter. The convection models proposed in this work do not require the use of active bonds (other than modulation signals), controlled sources, ad hoc elements, or any other special bond graph artifacts.

A Bond Graph Approach to the Analysis of Prosthesis for a Partially Impaired Hand

2006 ◽  
Vol 129 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Anand Vaz ◽  
Shinichi Hirai
Keyword(s):  
Bond Graph ◽  
Relative Orientation ◽  
Bond Graphs ◽  
Graph Models ◽  
Prosthetic Devices ◽  
Actuation Mechanism ◽  
Prosthetic Joints ◽  
System Equations ◽  
Analysis Of Dynamics ◽  
Prosthetic Finger

A system dynamics approach, based on bond graphs, is presented for the analysis of prosthetic devices for a partially impaired hand. The partial impairment implies that the hand has lost one or more fingers but retains the ability of its remaining natural fingers. It is shown that the existing natural joints can be used for the actuation of prosthetic finger joints and enable performance of tasks that would not have been possible otherwise. This is a challenging task as motion has to be transmitted from the remaining natural joints to the prosthetic joints. The joint axes move with respect to each other during performance of tasks and do not have any fixed relative orientation. In this work, basic concepts for the actuation of the prosthesis required for such tasks are developed systematically. Based on these concepts, Bowden cable based joint actuation mechanisms for transmission of motion from natural joints to corresponding prosthetic joints are presented and analyzed. The analysis of dynamics of the resulting under-actuated prosthesis with joint actuation mechanism is based on bond graph models that are systematically developed. Using these models, system equations are derived and numerical simulations performed for the analysis. One- and two-joint actuated prototypes of the prosthesis have been presented and effectively demonstrate the proposed concepts.

Bond Graphs for Distributed System Models Admitting Mixed Causal Inputs

1980 ◽  
Vol 102 (2) ◽  
pp. 94-100 ◽  
Author(s):  
D. L. Margolis
Keyword(s):  
System Dynamics ◽  
Distributed System ◽  
System Model ◽  
Frequency Range ◽  
Bond Graphs ◽  
High Frequencies ◽  
System Models ◽  
System Equations

Bond graphs are used for finite mode representations of distributed system dynamics. As long as all inputs to the system are “efforts” in a causal sense, then no formulation problems exist. However, if some of the system inputs are causal “flows”, then differential causality will exist and extremely tedious, often impossible, algebraic loops must be solved to formulate system equations. A procedure is developed which avoids these algebraic problems by including additional modal compliance in the system model without its associated modal inertia. The result of this approach is a finite mode distributed system model, devoid of artificially induced high frequencies, extremely accurate in a chosen frequency range, and capable of interacting with other distributed system models. The procedure is demonstrated through example.

Analysis of Acoustoelastic Systems Using Modal Bond Graphs

1990 ◽  
Vol 112 (1) ◽  
pp. 108-115 ◽  
Author(s):  
B. Samanta ◽  
A. Mukherjee
Keyword(s):  
System Dynamics ◽  
Natural Frequencies ◽  
Bond Graph ◽  
Bond Graphs ◽  
Two Stage ◽  
Modal Decomposition ◽  
Second Stage ◽  
Wide Range ◽  
Modal Truncation

A procedure is presented to study the dynamics of acoustoelastic systems within the framework of bond graph technique. The substructures, acoustic and structural, are modeled individually in form of bond graphs that are coupled through suitable elements satisfying the conditions at the interfaces. From this bond graph a second stage modal decomposition is performed to represent the overall system in yet another bond graph that can be analyzed to obtain the overall system dynamics. The scope for two-stage modal truncation makes the procedure suitable for analyzing acoustoelastic systems that are “stiff” in nature due to the wide range of their natural frequencies. The procedure is illustrated by suitable examples.

Pseudo Bond Graphs for Thermal Energy Transport

1978 ◽  
Vol 100 (3) ◽  
pp. 165-169 ◽  
Author(s):  
Dean Karnopp
Keyword(s):  
Thermal Energy ◽  
Energy Transport ◽  
Open Systems ◽  
Bond Graph ◽  
Bond Graphs ◽  
Flowing Fluid ◽  
Practical Applications ◽  
Heating And Cooling ◽  
Thermal Energy Transport ◽  
Normal Bond

Bond graphs have been shown to be useful in the modeling of a wide variety of physical dynamic systems, but open systems in which energy is transported across boundaries with mass flow have never been modeled as elegantly as fixed mass systems and their analogs. In this paper a bond graph, building block approach is outlined which allows most of the conceptual and practical advantages of normal bond graph techniques to be retained for systems in which thermal energy transported by a flowing fluid is important. Practical applications include the dynamic modeling of heating and cooling systems involving air and water. The method allows the imposition of a constant causal scheme independent upon the direction of fluid flow. The result is a pseudo bond graph since the use of temperature and heat flow as effort and flow means that the product of effort and flow is not power as in normal bond graphs.

scholarly journals Charting the Rough Journey to ‘Home’: The Contribution of Qualitative Longitudinal Research to Understandings of Homelessness in Austerity

2021 ◽  
pp. 1-17
Author(s):  
Emma Davidson ◽  
Briege Nugent ◽  
Sarah Johnsen
Keyword(s):  
Longitudinal Research ◽  
Support Service ◽  
Added Value ◽  
Small Scale ◽  
Deep Insight ◽  
Policy Makers ◽  
Analytical Potential ◽  
Longitudinal Approach ◽  
The Uk ◽  
Insight Into

This article reflects on the contribution of qualitative longitudinal research (QLR) to understandings of homeless peoples’ experiences of support service interventions in an era of austerity in the UK. It brings into ‘analytic conversation’ data from qualitative longitudinal evaluations of homeless support projects operated by voluntary sector organisations in Scotland. With fieldwork spanning 2014-2019, the analysis expands the analytical potential of pooling small-scale studies through an interrogation of individuals’ ‘journeys’ through homelessness services and their rough path to ‘home’. By reflecting on our substantive findings, the article explores the added value and challenges of a longitudinal approach. It concludes that while QLR can deliver deep insight into lives lived by vulnerable populations and potentially reduce the distance between policy makers and those affected, its benefits must be balanced against pragmatism and the ethical responsibilities associated with the method.

Bond Graph Sign Conventions

1975 ◽  
Vol 97 (2) ◽  
pp. 184-188 ◽  
Author(s):  
A. S. Perelson
Keyword(s):  
Graph Model ◽  
Bond Graph ◽  
Equivalence Classes ◽  
Parameter System ◽  
Bond Graphs ◽  
Lumped Parameter ◽  
Oriented Object

The lack of arbitrariness in the choice of bond graph sign conventions is established. It is shown that an unoriented bond graph may have no unique meaning and that with certain choices of orientation a bond graph may not correspond to any lumped parameter system constructed from the same set of elements. Network interpretations of these two facts are given. Defining a bond graph as an oriented object leads to the consideration of equivalence classes of oriented bond graphs which represent the same system. It is also shown that only changes in the orientation of bonds connecting 0-junctions and 1-junctions can lead to changes in the observable properties of a bond graph model.

scholarly journals Decision making in reverse logistics using system dynamics

2004 ◽  
Vol 14 (2) ◽  
pp. 259-272 ◽  
Author(s):  
P. Georgiadis ◽  
D. Vlachos
Keyword(s):  
Decision Making ◽  
System Dynamics ◽  
Reverse Logistics ◽  
Closed Loop ◽  
System Modeling ◽  
New Approach ◽  
Helpful Tool ◽  
Starting Point ◽  
Decision Making Tool

Reverse logistics is a modern field of consideration, research and study, providing helpful information on the operation of the closed-loop supply chain. Although the starting point of this field is traced back to the early 90?s, no standard method has been suggested, neither prevailed. The purpose of this paper is to introduce a new approach on the study of reverse logistics. It is actually a review on how System Dynamics (SD) can be a helpful tool when it is used in the reverse logistics field. The paper explains the basic theory of the system modeling and next it utilizes the reverse logistics model. Finally, an illustrative example shows how SD modeling can be used to produce a powerful long-term decision-making tool.

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