Modular Dynamic Model Research Articles

Modular Dynamic Phasor Modeling and Simulation of Renewable Integrated Power Systems

Modular Dynamic Phasor Modeling and Simulation of Renewable Integrated Power Systems

Application of (bio) chemical engineering concepts and tools to model genetic regulatory circuits, and some essential central carbon metabolism pathways in living cells. Part 4. Applications in the design of some Genetically Modified Micro-Organisms (GMOs)

In the first part of this work, the general Chemical and Biochemical Engineering (CBE) concepts and rules are briefly reviewed, together with the rules of the control theory of Nonlinear Systems (NSCT), all in the context of (i) deriving deterministic Modular Structured Kinetic Models (MSDKM) to describe the dynamics of metabolic processes in living cells, and (ii) of Hybrid Structured Modular Dynamic Models (HSMDM) (with continuous variables, linking the cell-nano-scale MSDKM state variables to the macro-scale state variables of the bioreactor dynamic model). Thus, in the HSMDM model, both prediction quality and its validity range are improved. By contrast, the current (classical/default) approach in bioengineering practice for solving design, optimization, and control problems based on the math models of industrial biological reactors is to use unstructured Monod (for cell culture reactor) or simple Michaelis-Menten (if only enzymatic reactions are retained) global kinetic models by ignoring detailed representations of metabolic cellular processes. By contrast, as reviewed, and exemplified in the second part of this work, an accurate and realistic math modelling of the dynamic individual GERMs (gene expression regulatory module), or genetic regulatory circuits (GRC), and cell-scale CCM (central carbon metabolism) key-modules can be done by only using the novel holistic ’Whole-Cell Of Variable-Volume’ (WCVV) modelling framework, under isotonic/homeostatic conditions/constraints introduced and promoted by the author. An example was given in the same Part 2 for the case study of a dynamic model for the oscillating glycolysis coupled with the Tryptophan (TRP) oscillating synthesis in the E. coli cells.

Modular Dynamic Modeling for On-Orbit Assembly of Large-Scale Space Structures

The large-scale space structure during on-orbit assembly is a time-varying system. The dynamic modeling problem of such incrementally increasing space structure is investigated, and a modular dynamic modeling approach is proposed in this paper. The dynamic model of each substructure is first established, and then, a database is designed to store substructure models, which is used for subsequent dynamic modeling in the assembly process. The fixed connection relationship between adjacent substructures is described by constraint conditions, which lead to the coefficient matrices of adjacent substructures being decoupled. The substructures are assembled in a given sequence, and then, the dynamic modeling, to describe the large-scale space structure on-orbit assembly, is gradually completed via using the proposed modeling approach. The numerical simulation is finally presented. The results demonstrate that the extra calculation resulting from the coefficient matrices coupling of adjacent substructures is avoided. Moreover, the proposed dynamic model can accurately describe the dynamic characteristics of the large-scale space structure during on-orbit assembly.

Application of Modular Expression of Bond Space in Muzzle Disturbance Analysis

In order to simulate the complex dynamic behavior of automata system and analyze muzzle disturbance, a modular dynamic model of automata was established based on bond space theory. The bond space modules of the cradle, gun box, barrel and projectile were defined, and the state equations of each module of the automata were deduced in terms of momentum space vector and position change space vector and their first derivative. The whole model is established by connecting the generalized potential source and generalized flow source of each module. On this basis, the muzzle disturbance analysis is carried out by solving the model, and the simulation results are consistent with the test results of the continuous firing test. It shows that the muzzle disturbance analysis model based on the modular representation of bond space is correct, and provides a new method for the dynamic analysis of the projectile and gun coupling launching system.

Real-time modular dynamic modeling for compression system of altitude ground test facilities

Modeling of a centrifugal compressor is of great significance to surge characteristics and fluid dynamics in the Altitude Ground Test Facilities (AGTF). Real-time Modular Dynamic System Greitzer (MDSG) modeling for dynamic response and simulation of the compression system is introduced. The centrifugal compressor, pipeline network, and valve are divided into pressure output type and mass flow output type for module modeling, and the two types of components alternate when the system is established. The pressure loss and thermodynamics of the system are considered. An air supply compression system of AGTF is modeled and simulated by the MDSG model. The simulation results of mass flow, pressure, and temperature are compared with the experimental results, and the error is less than 5%, which demonstrates the reliability, practicability, and universality of the MDSG model.

Variational multiscale reinforcement learning for discovering reduced order closure models of nonlinear spatiotemporal transport systems

A central challenge in the computational modeling and simulation of a multitude of science applications is to achieve robust and accurate closures for their coarse-grained representations due to underlying highly nonlinear multiscale interactions. These closure models are common in many nonlinear spatiotemporal systems to account for losses due to reduced order representations, including many transport phenomena in fluids. Previous data-driven closure modeling efforts have mostly focused on supervised learning approaches using high fidelity simulation data. On the other hand, reinforcement learning (RL) is a powerful yet relatively uncharted method in spatiotemporally extended systems. In this study, we put forth a modular dynamic closure modeling and discovery framework to stabilize the Galerkin projection based reduced order models that may arise in many nonlinear spatiotemporal dynamical systems with quadratic nonlinearity. However, a key element in creating a robust RL agent is to introduce a feasible reward function, which can be constituted of any difference metrics between the RL model and high fidelity simulation data. First, we introduce a multi-modal RL to discover mode-dependant closure policies that utilize the high fidelity data in rewarding our RL agent. We then formulate a variational multiscale RL (VMRL) approach to discover closure models without requiring access to the high fidelity data in designing the reward function. Specifically, our chief innovation is to leverage variational multiscale formalism to quantify the difference between modal interactions in Galerkin systems. Our results in simulating the viscous Burgers equation indicate that the proposed VMRL method leads to robust and accurate closure parameterizations, and it may potentially be used to discover scale-aware closure models for complex dynamical systems.

Experimental validation of a dynamic numeric model to simulate the thermal behavior of a facade

The process of analysis and design of energy saving measures aimed to reduce building energy consumption, both in the design of new constructions and in the refurbishment of existing ones, has led to the need to solve increasingly complex problems with the consequent demand to develop complex models and new calculation tools, which often entails the coupling of different models each one of them to solve a specific task and always under the requirement of obtaining accurate and reliable results. This article presents a modular dynamic model based on a finite difference scheme with matching conditions between wall layers to record the different thermophysical properties of layer materials and accurately compute the heat flux through the building envelope. The aim of this model is to simulate the energy behavior of building envelopes and to allow the connection, via a co-simulation procedure, with other codes based in models for addressing complex issues usually not included in standard Building Energy Simulation (BES) tools. For that, the simulation model was designed with a modular structure in order to facilitate its connection, when required, to other codes written in C++. The thermal model has been validated experimentally, using data from two full-scale outdoor test cells with different façade constructive solutions for different ventilation and blind opening regimes. An additional code-to-code comparison was also performed between the developed model and the Energy-Plus software to complement the results of the experimental validation. The results obtained in the validation process show the ability of the proposed numerical model to simulate the energy performance of the envelope and of the test cell globally in a wide variety of situations, predicting internal air temperature and envelope internal surfaces temperatures which meet the requirements usually established for the validation of building energy simulation tools. The numerical formulation of the introduced model and its characteristics that combine flexibility, modularity and accuracy for the calculation of the thermal behavior of a façade and is able of an easy connection to external codes written in C++ to solve more complex problems, allow to consider the present work as innovative and novelty on the literature.

Scalable modular dynamic molten salt reactor system model with decay heat

Nodal dynamic models allow rapid reduced-order simulations of complex systems. This paper presents a publicly available system dynamic model of a molten salt reactor system with a topology of the Molten Salt Reactor Experiment (MSRE), in MATLAB/Simulink, building upon a model previously published and validated with MSRE data. It adds scaling of nominal power, dynamic representation of decay heat generation, a generic decay heat removal system, improved documentation, modularity, and test cases. One hour of system transient runs in less than 10 min on a laptop. This model is intended for first order engineering calculations, developing insights into system transient behavior, equipment sizing, parameter sensitivity studies. The model contains an easy to use toolkit which can be customized and expanded to describe any molten salt reactor system. Scenarios involving off-normal transients are presented. Relation between shutdown reactivity insertions, decay heat removal, core recriticality, and safe shutdown conditions are discussed.

Natural Characteristics of Multi-Stage Planetary Drives for Space Manipulator Joints Based on Modular Dynamic Model

In this paper, a modular dynamic model of multi-stage planetary gear drive for space manipulator joints is presented so as to overcome the shortcomings of the traditional overall modeling approach. Based on the modular idea, the system mass and stiffness matrices are respectively divided into four sub-modular matrices, then the modular program for the eigenvalue and eigenvector calculation of multi-stage planetary system is developed. The presented modular calculation program of natural characteristics can be used for the computational analysis of natural frequencies and modal vectors of the planetary gear drive with arbitrary drive stages and arbitrary drive parameters. Meanwhile, taking the four-stage planetary gear drive system for space manipulator joints for example, through the call of the modular calculation program, its natural frequencies and modal vectors can be quickly and easily acquired.

Modular Dynamic Modeling Investigation of Multi-Stage Planetary Gears for Space Manipulator Joints

In order to overcome the shortcomings of the traditional modeling method, a modular modeling approach for the space manipulator joint transmission system in this paper is proposed. In the first place, the multi-stage planetary transmission system for the space manipulator joint is divided into several sub-modules, and the sub-modules of each level are established by considering the factors such as meshing stiffness, meshing errors and so on. In the second place, the dynamic differential equations of the multi-stage planetary transmission system for the space manipulator joint are obtained through the integration of each level modules. The proposed modular modeling approach is convenient for the dynamic behavior analysis and the quick choice of transmission scheme.

Progress on Fault Mechanisms for Gear Transmissions in Coal Cutting Machines: From Macro to Nano Models.

Numerical modeling has been recognized as the dispensable tools for mechanical fault mechanism analysis. Techniques, ranging from macro to nano levels, include the finite element modeling boundary element modeling, modular dynamic modeling, nano dynamic modeling and so forth. This work firstly reviewed the progress on the fault mechanism analysis for gear transmissions from the tribological and dynamic aspects. Literature review indicates that the tribological and dynamic properties were separately investigated to explore the fault mechanism in gear transmissions. However, very limited work has been done to address the links between the tribological and dynamic properties and scarce researches have been done for coal cutting machines. For this reason, the tribo-dynamic coupled model was introduced to bridge the gap between the tribological and dynamic models in fault mechanism analysis for gear transmissions in coal cutting machines. The modular dynamic modeling and nano dynamic modeling techniques are expected to establish the links between the tribological and dynamic models. Possible future research directions using the tribo dynamic coupled model were summarized to provide potential references for researchers in the field.

A dynamic subgrid-scale modeling framework for Boussinesq turbulence

A modular dynamic subgrid-scale modeling framework is presented for large eddy simulation of two-dimensional Boussinesq turbulence. The procedure we put forth in this study allows us to couple the structural subgrid-scale parameterization models with the functional models by minimizing the error between them. In particular, the approximate deconvolution procedure is used to estimate the Smagorinsky and Baldwin-Lomax eddy viscosity constants and the associated turbulent Prandtl numbers self-adaptively from the resolved flow quantities. Our numerical assessments for solving the Rayleigh-Bénard turbulent thermal convection problem show that the proposed approach could be used as a viable tool to address the turbulence closure problem for the Boussinesq setting due to its accuracy and flexibility.

A stable and scale-aware dynamic modeling framework for subgrid-scale parameterizations of two-dimensional turbulence

The physical mechanism of two-dimensional turbulence poses challenges for modeling subgrid-scale physics in large-scale geophysical flows. To this end, we put forth a modular dynamic modeling approach for subgrid-scale parameterizations of two-dimensional turbulence. For developing a unifying dynamic modeling approach, a set of coupled subgrid-scale models are proposed by minimizing the error between the functional and structural models. This approach is fundamentally different to the test-filtering based dynamical approach, which is also included in our analysis. Our efforts include two different functional nonlinear eddy viscosity kernels: (i) Smagorinsky’s strain-rate and (ii) Leith’s vorticity-gradient based formulations. The mixing length scales associated with these eddy viscosity kernels are dynamically computed from the local flow physics by incorporating the structural models based upon the scale similarity and approximate deconvolution approaches. A set of decaying turbulence experiments up to Re = 128,000 are compared against direct numerical simulations (DNSs) obtained by a resolution of 20482. First, it is shown that less dissipative results are generally obtained using Leith’s eddy viscosity kernel due to its more scale-selective behavior. Among the proposed hybrid models, it is seen that the dynamic Bardina approach yields the least dissipative results, followed by the dynamic Layton, and the dynamic AD models. Due to its more dissipative character, the dynamic AD model seems to be an efficient approach for very large eddy simulations on coarse grid descriptions. To elucidate the effects of numerics on the subgrid-scale physics, two different high-order discretization schemes are considered, namely the fourth-order Padé and Arakawa schemes. Based on numerical assessments we conclude that the choice of underlying numerical discretization plays a more important role than that of the subgrid modeling in obtaining an energy spectrum that closely approximates the DNS data.

Modular dynamic modeling and analysis of planar closed-loop mechanisms with clearance joints and flexible links

Dynamic analysis of a mechanism with clearance joints and flexible links is a research focus in the field of multibody dynamics. In this study, a general modular dynamic modeling approach based on Lagrange multiplier method for planar closed-loop mechanisms is proposed in order to improve the modeling efficiency and reusability of a structure having same topology. With this approach, dynamic analysis considering clearance joints and flexible links can be performed conveniently. A novel mathematical model to determine the relative motion modes between the two components of a clearance joint is developed based on the previous contact detection method. A complete dynamic effect evaluation system, which measures the influence of clearance joints and flexible links on the dynamic performances more conveniently and intuitively, is established. A planar 3-RRR parallel mechanism that is a closed-loop system including imperfect joints and flexible links is studied as an example. The dynamic model of this mechanism is established and its dynamic characteristics are investigated. The couple effects of clearance joints and flexible links for a parallel mechanism are investigated first. The contact forces existing in the clearance joints can cause system vibration and thus reduces the dynamic stability of the whole mechanical system. Meanwhile, the simulation results indicate that the flexible links can damp the vibration of the moving platform caused by clearance joints is certain.

A modular dynamic mathematical model of thermoelectric elements for marine applications

This paper presents a modular, dynamic and spatially distributed model of thermoelectric elements for marine applications intended to assess the low-grade waste heat recovery potential of thermoelectric devices on-board seagoing vessels. The model describes the dynamic behaviour of marine thermoelectric components and captures the detailed thermodynamic and thermoelectric process phenomena. Validation against experimental data from the literature indicates good model predictive ability. Two marine applications are examined using the model: (a) a scavenge air cooler, and (b) an auxiliary engine exhaust gas duct section integrated with thermoelectric generators. For each case, a parametric analysis is conducted to identify the designs that yield maximum thermoelectric efficiency and power output. The study concludes that thermoelectrics can recover low-grade waste heat on-board ships. Systems engineering modelling and simulation techniques can successfully determine the best system design, to achieve maximum energy harvesting, satisfying the weight, space and operational constraints on-board.

Dynamic Simulation Methodologies for Urban Energy Demand

This paper presents a new dynamic physical energy model of building for simulating the energy demand of cities. Firstly, a justification it is given regarding the necessity of a new building model and the advantages of using modular building simulation when dealing with large numbers of buildings in an urban context. The main motivation was a flexible and very modular interaction of 3D urban geometry description with the CityGML data format and energy related attributes for building parts.The paper then presents the modular dynamic building model and its validation with a real case of study for single buildings.The model integration into an urban modeling platform named SimStadt is explained with the necessary input data for a city heat demand calculation.

A Dynamic Simulation Model of Industrial Robots for Energy Examination Purpose

In this paper, a modular dynamic model of an industrial robot (IR) for predicting and analyzing its energy consumption is developed. The model consists of control systems, which include a state-of-the-art feedback linearization controller, permanent magnet synchronous drives and the mechanical structure with Coulomb friction and linear damping. By using the developed model, a detailed analysis of the influence of different parameter sets on the energy consumption and loss energy of IRs is investigated. The investigation results show that the operating parameters, robot motor drives, and mechanical damping and elasticity of robot transmissions have a significant effect on the energy consumption and accuracy of IRs. However, these parameters are not independent, but rather interrelated. For example, a higher acceleration and velocity shortens IRs’ operating periods, but needs a greater motor current, tends to excite vibrations to a greater extent, and thus produces a higher amount of loss energy.

Learning of semi-empirical neural network model of aircraft three-axis rotational motion

We analyze the problems of mathematical and computer simulation of the controlled motion of an aircraft when the knowledge about the object and its operation condition is insufficient. The goal of this paper is to develop a class of modular semi-empirical dynamic models that combine the capabilities of theoretical and neural network based simulations. We analyze the learning procedure of such models in generating a multi-step forecast.

Analysis of biogas compression system dynamics

The use of biogas for energy production has progressively increased in recent years, due to an increasing interest both in agricultural and energy policies of many industrialized countries. Biogas compression by means of natural gas infrastructure seems the most immediate solution, but could also lead to problems due to the different physical properties of the two gases. In this paper, a non-linear one-dimensional modular dynamic model is developed and used for the simulation of compression system transient behavior. The arrangement consists of a main line, where the compressor operates, and an anti-surge control, which consists of a recycle loop activated by a fast acting valve. Different maneuvers (start-up, normal operation, emergency shutdown and operating point variation) are simulated by using two different working fluids (methane and biogas). Simulations prove that the design of the surge protection system should consider the fluid to be elaborated. Moreover, system predisposition to surge increases as the ratio between system volumes and the inertia of the rotating masses increases.

Functional modular dynamic model of the surface layer of water

It was demonstrated that it is impossible to develop a universal model of a connected surface layer (SL) that would be applicable to all liquids. It was established that the degree of connectivity of the structure of the SL, a characteristic that determines its stability and the value of the surface tension it creates, depends on the stereochemical parameters of the constituent atoms and molecules (the valence angles and coordination numbers in connected structures composed of similar species). The use of the concept of the module, which underlies the description of the connectivity of stable solid structures, including crystals, in conjunction with the symmetrical assembly method, made it possible to develop an ultimately ordered two-dimensional crystalline model (approximant) of the connected structure of an ∼5-A SL of water composed of unitary modular building blocks. An invariant in the form of a network of water molecules with free H-bonds was identified. This invariant governs the interaction of the SL with hydrophilic groups of surfactants and polymers. The specifics of the structure of the SL of water entirely determines its functional properties, such as the superplasticity, high conductivity, polarization of its sides, permeability to ions and gas molecules, perfect wettability (or nonwettability) of some substances, etc. The mechanisms operative at the different stages of the cooperative transformation of the structure of the water SL approximant during its interaction with surfactant molecules, up to the formation of the final form of the Langmuir monolayer, were considered. For each stage of the transformation of the approximant under the action of surfactant molecules and the external compression pressure during the formation of the monolayer, the surface area per surfactant molecule was calculated. The proposed approach makes it possible to treat the formation of Langmuir monolayers in a way that differs from the commonly accepted one.