Application of Meshless Pore-Level Model to Pyrolysis and Synthesis of Nuclear Fuels

2007 ◽  
Author(s):  
Xiaolin Wang ◽  
Hui Zhang ◽  
Lili Zheng
Keyword(s):  
Material Processing ◽  
Transport Phenomena ◽  
Nuclear Material ◽  
Processing Technique ◽  
System Level ◽  
Scale Model ◽  
Nuclear Fuels ◽  
Particle Hydrodynamics ◽  
Level Model ◽  
Pore Level

Uranium-ceramic nuclear fuels can be fabricated through pyrolysis-based materials processing technique. This technique requires lower energy compared to sintering route. During the fabrication process, the source material changes composition continuously and chemical reactions and transport phenomena vary accordingly. Therefore, to obtain such nuclear fuel materials with high uniformity of microstructure/species without crack, transport phenomena in the material processing needs to be better understood. A system-scale model has been developed to account for the pyrolysis-based uranium-ceramic nuclear material processing in our prior work. In this study, a pore-scale numerical model based on Smoothed Particle Hydrodynamics (SPH) will be described for modeling the synthesis of SiC matrix and U3O8. The system-level model provides thermal boundary conditions to the pore-level model. The microstructure and compositions of the produced composites will be studied. Since the control of process temperature plays an important role in the material quality, the effects of heating rate and U3O8 particle size and volume on species uniformity and microstructure are investigated.

scholarly journals Dynamic modelling of a servo self-pierce riveting (SPR) process

2021 ◽  
pp. 095440542110374
Author(s):  
Daniel Tang ◽  
Mike Evans ◽  
Paul Briskham ◽  
Luca Susmel ◽  
Neil Sims
Keyword(s):  
Dynamic Modelling ◽  
System Level ◽  
Optimum Process ◽  
Current Limit ◽  
Level Model ◽  
System Level Model ◽  
Head Height ◽  
Extensive Experimental Data ◽  
High Level

Self-pierce riveting (SPR) is a complex joining process where multiple layers of material are joined by creating a mechanical interlock via the simultaneous deformation of the inserted rivet and surrounding material. Due to the large number of variables which influence the resulting joint, finding the optimum process parameters has traditionally posed a challenge in the design of the process. Furthermore, there is a gap in knowledge regarding how changes made to the system may affect the produced joint. In this paper, a new system-level model of an inertia-based SPR system is proposed, consisting of a physics-based model of the riveting machine and an empirically-derived model of the joint. Model predictions are validated against extensive experimental data for multiple sets of input conditions, defined by the setting velocity, motor current limit and support frame type. The dynamics of the system and resulting head height of the joint are predicted to a high level of accuracy. Via a model-based case study, changes to the system are identified, which enable either the cycle time or energy consumption to be substantially reduced without compromising the overall quality of the produced joint. The predictive capabilities of the model may be leveraged to reduce the costs involved in the design and validation of SPR systems and processes.

A CFD-supported dynamic system-level model of a sodium-cooled billboard-type receiver for central tower CSP applications

Solar Energy ◽  
2019 ◽  
Vol 177 ◽  
pp. 576-594 ◽  
Author(s):  
M. Cagnoli ◽  
A. de la Calle ◽  
J. Pye ◽  
L. Savoldi ◽  
R. Zanino
Keyword(s):  
Dynamic System ◽  
System Level ◽  
Level Model ◽  
System Level Model

Implementation of a Fuel Cell System Model Into Building Energy Simulation Software IDA-ICE

2006 ◽  
Vol 4 (4) ◽  
pp. 511-515 ◽  
Author(s):  
Teemu Vesanen ◽  
Krzysztof Klobut ◽  
Jari Shemeikka
Keyword(s):  
Fuel Cell ◽  
Cell Model ◽  
Building Energy ◽  
Cell System ◽  
System Model ◽  
System Level ◽  
Fuel Cell System ◽  
Cell Systems ◽  
Level Model ◽  
System Level Model

Due to constantly increasing electricity consumption, networks are becoming overloaded and unstable. Decentralization of power generation using small-scale local cogeneration plants becomes an interesting option to improve economy and energy reliability of buildings in terms of both electricity and heat. It is expected that stationary applications in buildings will be one of the most important fields for fuel cell systems. In northern countries, like Finland, efficient utilization of heat from fuel cells is feasible. Even though the development of some fuel cell systems has already progressed to a field trial stage, relatively little is known about the interaction of fuel cells with building energy systems during a dynamic operation. This issue could be addressed using simulation techniques, but there has been a lack of adequate simulation models. International cooperation under IEA/ECBCS/Annex 42 aims at filling this gap, and the study presented in this paper is part of this effort. Our objective was to provide the means for studying the interaction between a building and a fuel cell system by incorporating a realistic fuel cell model into a building energy simulation. A two-part model for a solid-oxide fuel cell system has been developed. One part is a simplified model of the fuel cell itself. The other part is a system level model, in which a control volume boundary is assumed around a fuel cell power module and the interior of it is regarded as a “black box.” The system level model has been developed based on a specification defined within Annex 42. The cell model (programed in a spreadsheet) provides a link between inputs and outputs of the black box in the system model. This approach allows easy modifications whenever needed. The system level model has been incorporated into the building simulation tool IDA-ICE (Indoor Climate and Energy) using the neutral model format language. The first phase of model implementation has been completed. In the next phase, model validation will continue. The final goal is to create a comprehensive but flexible model, which could serve as a reliable tool to simulate the operation of different fuel cell systems in different buildings.

Fast Transaction-Level Model for Direct Memory Access Controller

2019 ◽  
Vol 28 (04) ◽  
pp. 1950059
Author(s):  
Mona Safar ◽  
Magdy A. El-Moursy ◽  
Ahmed Tarek ◽  
Ahmed Emad ◽  
Ahmed Hesham ◽  
...  
Keyword(s):  
Open Source ◽  
Direct Memory Access ◽  
System Level ◽  
The Past ◽  
Simulation Speed ◽  
Proposed Model ◽  
Level Model ◽  
Data Bus ◽  
Transaction Level ◽  
Simulation Time

Transaction-Level Modeling (TLM) has been widely used in system-level design in the past few years. Simulation speed of Virtual Platforms (VPs) depends mainly on the transactions which are initiated by the Programmer’s View (PV) models of the VP devices. PV models are required to run at highest simulation speed. Data bus width as a hardware (HW) parameter should not reduce simulation speed of the modeled transactions. Furthermore, HW-related parameters should only be accounted for when considering timing of the models. A fast SystemC-TLM model is developed for the widely used ARM PrimeCell PL080 DMAC IP. The performance of the proposed model is validated against a developed RTL model for the same device. The effect of the transactions granularity on simulation speed is determined. Different programmed transfers are simulated and compared with open-source Quick Emulator (QEMU)-based models. The developed model is compared with the developed RTL, the open-source QEMU model, and the existing ARM Fast Model (AFM). It is shown that simulation time of the developed model is reduced by two orders of magnitude as compared to the other existing models.

Optimal Control of a Multirotor Unmanned Aerial Vehicle Based on a Multiphysical Model

2020 ◽  
Author(s):  
Nicolas Michel ◽  
Zhaodan Kong ◽  
Xinfan Lin
Keyword(s):  
Optimal Control ◽  
Unmanned Aerial Vehicle ◽  
Operation Time ◽  
Rigid Body Dynamics ◽  
System Level ◽  
Optimal Velocity ◽  
Rotor Aerodynamics ◽  
Time Optimal ◽  
Aerial Vehicle ◽  
Level Model

Abstract Electric multirotor aircraft with vertical-take-off-and-landing capabilities are emerging as a revolutionary transportation mode. This paper studies optimal control of a multirotor unmanned aerial vehicle based on a system-level multiphysical model. The model considers aerodynamics of the rotor-propeller assembly, electro-mechanical dynamics of the motor and motor controller, and rigid-body dynamics of the vehicle, as control based on a system-level model incorporating all these dynamics and their coupling is missing in literature. A forward flight operation is considered for time-optimal and energy-optimal control, as well as battery voltages of 25 V and 21 V. Energy-optimal control is shown to reduce the energy required for the operation by 38.5% at 25 V, while reducing the battery voltage increases the minimum operation time by 19.8%. The energy-optimal cruise velocity is also examined, demonstrating that the optimal velocity predicted without considering rotor aerodynamics uses 35.2% more energy per meter travelled than is required at the true optimal velocity.

scholarly journals Extraction of Boundary Condition Independent Dynamic Compact Thermal Models of LEDs—A Delphi4LED Methodology

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1628 ◽  
Author(s):  
Robin Bornoff
Keyword(s):  
Boundary Condition ◽  
Ad Hoc ◽  
Thermal Response ◽  
System Level ◽  
Detailed Model ◽  
Thermal Models ◽  
Level Model ◽  
System Level Model ◽  
Transient Thermal ◽  
Transient Thermal Response

Multi-domain electro-thermal-optical models of LEDs are required so that their thermal and optical behavior may be predicted during a luminaire design process. Today, no standardized approach exists for the extraction of such models. Therefore, models are not readily provided by LED suppliers to end-users. This results in designers of LED-based luminaires wasting time on LED characterization and ad hoc model extraction themselves. The Delphi4LED project aims to address these deficiencies by identifying standardizable methodologies to extract both electro-optical and thermal compact models of LEDs that together can be used in a multi-domain simulation context. This article describes a methodology to extract compact thermal models of LEDs that are dynamic, in that they accommodate transient thermal effects, and are boundary condition-independent, in that their accuracy is independent of their thermal operating environment. Such models are achieved by first proposing an equivalent thermal nodal network topology. The thermal resistances and capacitances of that network are identified by means of optimization so that the transient thermal response of the network matches that of either an equivalent calibrated 3D thermal model or a transient thermal measurement of a physical sample. The accuracy of the thermal network is then verified by comparing the thermal compact model with a 3D detailed model, which predicts thermal responses within a 3D system-level model.

scholarly journals System-Level Model and Simulation of a Frequency-Tunable Vibration Energy Harvester

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 91 ◽  
Author(s):  
Sofiane Bouhedma ◽  
Yongchen Rao ◽  
Arwed Schütz ◽  
Chengdong Yuan ◽  
Siyang Hu ◽  
...  
Keyword(s):  
Energy Harvester ◽  
Element Model ◽  
Industrial Applications ◽  
System Level ◽  
Dual Frequency ◽  
Frequency Range ◽  
Vibration Energy Harvester ◽  
Resonance Frequencies ◽  
Level Model ◽  
System Level Model

In this paper, we present a macroscale multiresonant vibration-based energy harvester. The device features frequency tunability through magnetostatic actuation on the resonator. The magnetic tuning scheme uses external magnets on linear stages. The system-level model demonstrates autonomous adaptation of resonance frequency to the dominant ambient frequencies. The harvester is designed such that its two fundamental modes appear in the range of (50,100) Hz which is a typical frequency range for vibrations found in industrial applications. The dual-frequency characteristics of the proposed design together with the frequency agility result in an increased operative harvesting frequency range. In order to allow a time-efficient simulation of the model, a reduced order model has been derived from a finite element model. A tuning control algorithm based on maximum-voltage tracking has been implemented in the model. The device was characterized experimentally to deliver a power output of 500 µW at an excitation level of 0.5 g at the respected frequencies of 63.3 and 76.4 Hz. In a design optimization effort, an improved geometry has been derived. It yields more close resonance frequencies and optimized performance.

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