Multi-domain Unified Modeling Research Articles

Modeling and simulation of a micro gas-cooled nuclear reactor using Modelica

Highly compact micro nuclear reactors, which offer extensive energy benefits across ocean, land, space, and sky applications, have recently emerged as a popular research topic within the international nuclear industry. Due to its excellent inherent safety characteristics, the gas-cooled graphite-moderated reactor with TRISO fuel has attained extensive attention. Nonetheless, micro-reactors exhibit a high degree of system integration, characterized by the tight coupling and mutual constraints among various system functions. Conventional discipline-specific decoupled design patterns find it challenging to tackle the complexity arising from multi-disciplinary couplings. In response, this paper investigates the application of Modelica, a multi-domain unified modeling language, to construct models for several subsystems, encompassing the reactor, energy conversion system, and control system. This approach aims to enhance support for cross-disciplinary design. The accuracy of the reactor core model was verified by high-fidelity CFD simulation results, demonstrating a good agreement. Further investigations were then conducted on the safety and operational characteristics of the whole system. Typically, two simulations were conducted on the Gas cooled micro nuclear reactor (GCMR) design: one focused on an anticipated transients without scram accident scenario and the other on load-following operation. The simulation results demonstrated that the reactor possesses excellent inherent safety, even during extreme accidents. In such scenarios, the reactor is able to achieve shutdown solely through the negative reactivity resulting from increased core temperature. Furthermore, considering the heat accommodated in the reactor system and the constantly generated decay heat, a passive air-cooling mechanism has been investigated and successfully demonstrated with the model. The reactor also exhibits good load-following performance, which can be achieved by simply adjusting helium inventory (or pressure) and control drum position, while maintaining constant core temperature and power generation efficiency. These results can be leveraged to provide guidelines for further detailed designs of the GCMR.

Digital twin-driven virtual commissioning of machine tool

The commissioning of Computerized Numerical Control Machine Tools (CNCMTs) is particularly important and the commissioning quality directly affects its product processing. However, traditional commissioning methods are not suitable for complex and changeable machining conditions during operation, and the derived commissioning results have limited effectiveness. Therefore, this paper proposes a digital twin-driven virtual commissioning method to simulate the machining processes in a virtual environment and perform virtual commissioning to obtain better commissioning results. Firstly, a digital twin model is constructed using a multi-domain unified modeling language combined with a virtual-real mapping strategy to describe the response characteristics of CNCMTs. Secondly, a complex machining scene is simulated based on the twin model, and a virtual commissioning strategy and platform are constructed in this environment. Finally, the effectiveness of the proposed method is verified by taking the spindle system of CNCMTs as an example. The experimental results show a 13% short in response time and a 54% reduction in total systematic error along with a decrease in commissioning time.

Application of Three-Flow Fusion Technology Based on Modelica in Thermal Power Digital Twin

Thermal power plants gather large energy infrastructure; therefore, massive historical and real-time data of equipment operation will be generated in daily operation. Digital industrialization puts forward higher requirements for the use of big data than simple tasks, such as generating reports. MWorks is a multidomain unified modeling and simulation platform based on the Modelica language. In this study, MWorks is used to realize the modeling of multidomain systems, including electrical, thermal, mechanical, fluid, and heat transfer, in power plants. The test, calibration, verification, parameter optimization, and fault diagnosis of the thermal power plant mathematical models, which are historical and real-time data-driven, are discussed. The technology of three-flow fusion, including material flow, energy flow, and information flow, and its application in thermal power digital twin are explored.

Modelica-based simulation and optimization of design parameters of RAT actuator

The actuator is the key to ensure the normal startup and operation of the ram air turbine (RAT) system. In order to improve the reliability of the actuator of the RAT system, we propose a RAT actuator simulation modeling and design parameter optimization method based on the multi domain unified modeling language Modelica. Firstly, a fault tree is established to identify the components that cause the main failure modes of the actuator based on the actual cases of the RAT. Secondly, the model of RAT actuator is built by using Modelica language. The correctness of the model is verified by comparing with the actual use, with the error of about 3.78%. Finally, in order to avoid oil leakage caused by excessive hydraulic oil pressure, under the premise of meeting the constraints of the actuator deployment time and the end deployment speed, the optimal design parameters are determined by simulation when the peak pressure of the hydraulic oil is minimized. The research results can provide reference for the forward design of RAT in China and have good engineering application value.

Digital twin for CNC machine tool: modeling and using strategy

As a typical manufacturing equipment, CNC machine tool (CNCMT), which is the mother machine of industry, plays an important role in the new trend of smart manufacturing. As the requirement of smart manufacturing, the abilities of its self-sensing, self-prediction and self-maintenance are necessary. In order to make CNCMT become more intelligent, a research about Digital twin (DT) for CNCMT is conducted. In this research, a multi-domain unified modeling method of DT is established, a mapping strategy between physical space and digital space is explored, and an autonomous strategy of DT is proposed. These methods can optimize the running mode, reduce the sudden failure probability and improve the stability of CNCMT. Finally, this paper provides a demonstration of DT model building and using strategy in fault prediction and diagnosis for CNC milling machine tool.

Multi-Domain Modeling Based on Modelica

With the application of simulation technology in large-scale and multi-field problems, multi-domain unified modeling become an effective way to solve these problems. This paper introduces several basic methods and advantages of the multidisciplinary model, and focuses on the simulation based on Modelica language. The Modelica/Mworks is a newly developed simulation software with features of an object-oriented and non-casual language for modeling of the large, multi-domain system, which makes the model easier to grasp, develop and maintain.It This article shows the single degree of freedom mechanical vibration system based on Modelica language special connection mechanism in Mworks. This method that multi-domain modeling has simple and feasible, high reusability. it closer to the physical system, and many other advantages.

Multi-Domain Unified Modeling and Simulation of the Electrical Vehicle

Due to the simulation of electric vehicle usually includes several domains which is difficult to integrate when the models are from different disciplinaries. In this paper, a library of the Electrical Vehicle is built using the unified multidisciplinary modeling language Modelica to model chassis, motor, batteries, and driver. And then the interfaces of different sub-systems is defined to assemble the sub-systems of the vehicle. Finally, some examples on the performance of Stability control of the Electrical Vehicle are implemented to verify the correctness of the model and the validity of the method.

Modeling and Simulation of the PMSM-Precision Reducer System with Modelica

There is still lack of effective modeling and simulation method for complex electromechanical coupling system. Modelica is a multi-domain unified modeling language to solve the modeling and simulation problems of the complex and heterogeneous physical systems. Dymola is a Modelica-based modeling and simulation platform for the complex physical systems. In this paper, the dynamics model of the permanent magnet synchronous motor (PMSM)-precision reducer system is established using Lagrange-Maxwell equation. The simulation model of this system is set up with Modelica language. The simulation of the system is realized in Dymola. Results show that the system can respond to good static and dynamic characteristics under a given speed for different loads. The dynamics model of the PMSM-precision reducer system can be further used in system control and optimization. The proposed modeling and simulation method based on Modelica may be commonly applied to other complex electromechanical systems.

Computer-Aided Multi-Domain Unified Modeling and Simulation for Aircraft Landing Gear

In order to model complex product systems and analyze their whole performance to deal with the coupling relationships between multi-domain，aircraft landing gear selected as the object, unified multi-domain modeling and simulation and for complex product systems was studied. The aircraft leading gear is decomposed as structure, and the mathematical models of the landing gear components are established. The model library of the landing gear components was developed using Modelica-based platform and multi-domain unified model of the landing gear was established. The impact work amount, the vertical load and the stroke are selected as the indexes to simulate and analyze the earthquake resistant performance of the shock absorber.

Multi-Domain Unified Modeling and Simulation for Aircraft Landing Gear Using Modelica

Modern products become more and more complex, the modeling and simulation of them are carried out with different software on heterogeneous platforms, which always caused the heterogeneous data, separated disciplines and cannot obtain the result of unified model correctly. Therefore, a Modelica-based modeling and simulation method for aircraft landing gear is proposed. The landing gear library based on Modelica was established. The unified physical model of landing gear which is composed of structural, thermodynamics and hydromechanics disciplines is constructed. The aircraft landing process, the track of retraction mechanism and the impact work amount of the shock absorber are obtained through multi-domain unified simulation, which provides references for deisgners.

A collaborative platform for complex product development based on multi-domain unified modeling and simulation

In order to intensify market competition, manufacturing enterprises must improve their product innovation capability. It is difficult to integrate the system modeling, simulation and collaborative process management in complex product development. A collaborative platform for complex product development based on multi-domain unified modeling and simulation is proposed in this paper. The architecture of the platform is firstly stated. The idea and realization of three key technologies, i.e. multi-domain modeling and simulation for complex product, knowledge management for product design and simulation, multi-domain collaborative mechanism, are emphasized. Finally, an industry case is given. The demonstration of the system shows that integration architecture is the effective infrastructure for multi-domain collaborative product development.

Research on Multi-Domain Unified Modeling and Optimization of a Micro Mirror

Referring to the natures of nonlinear dynamics and coupled energy domains presented by Micro-Opto-Electro-Mechanical Systems (MOEMS), a multi energy domain unified simulation language (modelica) based coupled modeling, simulation and optimization methodology is put forward. Then by choosing a micro mirror as the example, corresponding multi energy domain unified modeling and simulation processes of such a coupled micro device show the efficiency and convenience of this advanced modeling method. The dynamic input/output curves comparison also shows that the simulation result is accurate enough for system level design. At last, by using genetic optimization algorithm, the characteristics input/output curves of the micro mirror are converged to meet the ideal design requirement curves after 700 generations evolution. It proves the accuracy and efficiency of this system level simulation and optimization method.

Research on Multi-Domain Unified Modeling and Simulation of a Micro Electro-Thermal Actuator

Referring to the natures of nonlinear dynamics and coupled energy domains presented by Micro-Electro-Mechanical Systems (MEMS), a multi energy domain unified simulation language (modelica) based coupled modeling and simulation methodology is put forward. Then by choosing a micro electro-thermal actuator as the example, corresponding multi energy domain unified modeling and simulation processes of such a coupled micro device, which covers mechanical energy domain, electric energy domain and thermal energy domain, show the efficiency and convenience of this advanced modeling method. At last, through simulation result comparison with device level FEA simulation result and experimental result, the maximum relative error between numerical calculation result and experimental result is less than 4.2%. It proves the accuracy of this system level simulation method.