the Electrical Library for Rand Model Designer (RMD) is presented. RMD is the tool for modeling and simulation of complex dynamical systems with object-oriented modeling language (Model Vision Language). Users of Elec...
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ISBN:
(纸本)9781665404761
the Electrical Library for Rand Model Designer (RMD) is presented. RMD is the tool for modeling and simulation of complex dynamical systems with object-oriented modeling language (Model Vision Language). Users of Electrical Library have a possibility to build complex hierarchical multi-component electrical schemes using existing components and also modify them and add one's own. Using state machines for designing components with event-driven behavior and models with variable structure is the distinctive characteristic of Rand Model Designer. Models written in MVL (RMD) and Modelica (OpenModelica) concurrently illustrate the features of the library.
Modelica is an object-oriented modeling language whose design and features facilitate the description of cyber-physical systems (CPS). Message passing communication (MPC), seen as the transmission of impulses of infor...
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Modelica is an object-oriented modeling language whose design and features facilitate the description of cyber-physical systems (CPS). Message passing communication (MPC), seen as the transmission of impulses of information between model components, eases the description of the discrete-event parts of CPS models. However, Modelica does not currently supports MPC. Modelica supports an equation-based component connection rationale, where Modelica tools automatically transform component connections into model equations, following a physical modeling approach. The differences between MPC and Modelica connections are analyzed. A proposal for supporting MPC in Modelica is presented, inspired by the coupled PDEVS model communication approach. The presented MPC proposal is based on the definition of structures to manage messages, named buffers, interface ports and communication channels. Also, an implementation of the proposed MPC mechanism in the form of a new free Modelica library, named MSGLib, is presented. MSGLib includes functionality to manage and dynamically store messages, and describe component communications. Two examples, a pick and place system and a robotic arm, are presented to demonstrate the use of the library, and its combination with other Modelica models.
Future concepts and key technologies for reusable launch vehicles are currently investigated by the DLR project AKIRA, focusing on vertical takeoff and horizontal landing (VTHL), as well as horizontal takeoff and hori...
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Future concepts and key technologies for reusable launch vehicles are currently investigated by the DLR project AKIRA, focusing on vertical takeoff and horizontal landing (VTHL), as well as horizontal takeoff and horizontal landing (HTHL) concepts. Dedicated developments of multidisciplinary frameworks for launch vehicle modeling and preliminary design optimization have been presented in the relevant literature. These activities are often performed by several independent and discipline-specific tools;such an approach can only account for limited interactions of the involved disciplines with the overall system dynamics. Therefore, the objective of this paper is to focus on a multidisciplinary launch vehicle dynamics modeling, guidance, and control framework to support reusable launch vehicle design activities at DLR while taking into account the highly interconnected disciplines involved and changing environmental conditions. The modeling framework is based on the object-oriented, multidisciplinary, and equation-based modeling language MODELICA. Dedicated 3-DOF and 6-DOF model implementations, covering the kinematics and dynamics formulation, environmental effects, aerodynamics, and propulsion models are presented. Within this framework, a method to obtain a direct connection between 3-DOF and 6-DOF models is shown. This is done by considering results from the trajectory optimization package 'trajOpt' in combination with nonlinear 6-DOF inverse models obtained automatically by MODELICA. Angular rates and resulting moments can be retrieved by this intermediate 6-DOF modeling approach for subsequent controllability studies. We discuss some of these benefits in terms of nonlinear flight control simulations for an HTHL reusable launch vehicle concept.
This paper deals with the adaptation of energy-based realization-preserving model-reduction techniques for object-oriented models implemented in Modelica. An approach originally developed for bond graphs, where energy...
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This paper deals with the adaptation of energy-based realization-preserving model-reduction techniques for object-oriented models implemented in Modelica. An approach originally developed for bond graphs, where energy-related heuristics were used to identify the components contributing the most to the model's salient dynamics, was extended to more heterogeneously formulated models in Modelica. A prototype toolbox was developed inside the modeling environment OpenModelica. Its applicability was demonstrated with two examples. Although the model-reduction tool cannot reduce the model completely automatically, it may still offer many useful insights and hints to the user.
This work shows the learning results obtained from the use of a technique proposed and applied by the authors called Literature Based modeling Learning. This technique consists of the development of modeling tasks whe...
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ISBN:
(纸本)9781728184500
This work shows the learning results obtained from the use of a technique proposed and applied by the authors called Literature Based modeling Learning. This technique consists of the development of modeling tasks where the input is a text that represents a literature piece and the output is a set of diagrams that model that LP. The literature piece is typically a well-known short story but it can also be the lyrics of a song or hymn or even a prayer. This technique has been used during the last eight semesters at a Mexican university. A results of a study are presented to identify possible benefits with the use of this technique.
In this paper, a novel model of a switched reluctance generator is established. And based on the idea of object-oriented modeling, the stator, rotor, power converter, current chopper, and PID controller of the switche...
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ISBN:
(数字)9781728151694
ISBN:
(纸本)9781728151694
In this paper, a novel model of a switched reluctance generator is established. And based on the idea of object-oriented modeling, the stator, rotor, power converter, current chopper, and PID controller of the switched reluctance generator are modeled. And Modelica is used as the modeling language. The most complex part of building a switched reluctance generator model is its nonlinear characteristics. There are two nonlinear relations. The first one is that the machine flux linkage is dependent on the stator current and rotor position. Another one is that the electromagnetic torque is also dependent on the stator current and rotor position. The nonlinear characteristics are generally described by the finite element method and the function approximation method. This paper uses both methods to establish a switched reluctance generator model, and then compares the simulation results of the models established by the two methods. The model of the switched reluctance generator established in this paper is a three-phase self-excited switched reluctance generator with three pairs of stators and two pairs of rotors as an example.
The modular high temperature gas-cooled reactor nuclear power plant adopts an innovative "multi-modules with one turbine" power generation structure. Due to complex process mechanism, strict operation condit...
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ISBN:
(纸本)9781728176871
The modular high temperature gas-cooled reactor nuclear power plant adopts an innovative "multi-modules with one turbine" power generation structure. Due to complex process mechanism, strict operation conditions, and lack of practical operation experience of the new technique, how to keep the power plant safe, stable, economical and efficient becomes an urgent problem to be solved. In this paper, a real-time optimization strategy based on mechanism model is adopted, an object-oriented modeling strategy is used to construct a modular equation oriented first principles model of nuclear power plant, a systematic multi-parameters simultaneous estimation method and sensitivity analysis method are used in parameter modification and model reconstruction during the optimization process. Based on previous work, a trust region framework is introduced to ensure the local calculation accuracy of the model. Finally, the article validates the effectiveness of the real-time optimization strategy through significant load changes in modular high temperature gas-cooled reactor nuclear power plant.
In the last two decades, about a dozen proposals were made to extend object-oriented modeling by multiple abstraction levels. One group of proposals designates explicit levels to objects and classes. The second group ...
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ISBN:
(纸本)9781450381352
In the last two decades, about a dozen proposals were made to extend object-oriented modeling by multiple abstraction levels. One group of proposals designates explicit levels to objects and classes. The second group uses the powertype pattern to implicitly establish levels. From this group, we consider two proposals, DeepTelos and MLT*. Both have been defined via axioms and both give a central role to the powertype pattern. In this paper, we reconstruct MLT* with the deductive axiomatization style used for DeepTelos. The resulting specification is executed in a deductive database to check MLT* multi-level models for errors and complete them with derived facts that do not have to be explicitly asserted by modelers. This leverages the rich rules of MLT* with the deductive approach underlying DeepTelos. The effort also allows us to clearly establish the relation between DeepTelos and MLT*, in an attempt to clarify the relations between approaches in this research domain. As a byproduct, we supply MLT-Telos as a fully operational deductive implementation of MLT* to the research community.
Large penetration of renewable distributed energy resources, as well as the effective integration of storage systems and electric vehicles, are some of the required strategies to reduce the impact of the energy sector...
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ISBN:
(纸本)9781728193656
Large penetration of renewable distributed energy resources, as well as the effective integration of storage systems and electric vehicles, are some of the required strategies to reduce the impact of the energy sector on greenhouse gas emissions. Microgrids offer an efficient platform to facilitate the integration of these systems, however, the increased complexity this strategy comes with, requires the use of sophisticated, reliable, and secure monitoring and control systems. The outbreak of cryptocurrency technologies has drawn particular attention, especially, the underlying Blockchain technology. The decentralized structure of this technology enables implementing control strategies, parameters monitoring, and business processes in microgrids. The aim of this work is to present the development of a framework to monitor operational parameters from an islanded microgrid. To build the Blockchain network, the Hyperledger-Fabric development platform was used. To simulate the behavior of the microgrid, an object-oriented open-source library using the Modelica modeling language was used to model a DC microgrid. The performance of the architecture was evaluated through operational parameters such as the difficulty and the number of nodes. Results suggest that changes in these factors can affect significantly the transaction time. The proposed architecture can be used as a basis to study Blockchain communication effects in smart grids and their development.
In Germany, bridges have an average age of 40 years. A bridge consumes between 0.4% and 2% of its construction cost per year over its entire life cycle. This means that up to 80% of the construction cost are additiona...
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In Germany, bridges have an average age of 40 years. A bridge consumes between 0.4% and 2% of its construction cost per year over its entire life cycle. This means that up to 80% of the construction cost are additionally needed for operation, inspection, maintenance, and destruction. Current practices rely either on paper-based inspections or on abstract specialist software. Every application in the inspection and maintenance sector uses its own data model for structures, inspections, defects, and maintenance. Due to this, data and properties have to be transferred manually, otherwise a converter is necessary for every data exchange between two applications. To overcome this issue, an adequate model standard for inspections, damage, and maintenance is necessary. Modern 3D models may serve as a single source of truth, which has been suggested in the Building Information modeling (BIM) concept. Further, these models offer a clear visualization of the built infrastructure, and improve not only the planning and construction phases, but also the operation phase of construction projects. BIM is established mostly in the Architecture, Engineering, and Construction (AEC) sector to plan and construct new buildings. Currently, BIM does not cover the whole life cycle of a building, especially not inspection and maintenance. Creating damage models needs the building model first, because a defect is dependent on the building component, its properties and material. Hence, a building information model is necessary to obtain meaningful conclusions from damage information. This paper analyzes the requirements, which arise from practice, and the research that has been done in modeling damage and related information for bridges. With a look at damage categories and use cases related to inspection and maintenance, scientific literature is discussed and synthesized. Finally, research gaps and needs are identified and discussed.
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