System Simulation Research Articles

Turbine selection for hydraulic energy recovery in the Yuribia dam aqueduct

The recuperation of hydraulic energy in aqueducts is based on utilizing the energy dissipated by hydraulic devices aimed at regulating the flow or pressure within the system, in addition to fulfilling their primary purpose. This paper presents the methodology for the selection of a turbine coupled to a generator for the recovery of hydraulic energy in the aqueduct of the Yuribia dam situated in the state of Veracruz, Mexico. The results of system modeling, simulation, and calculation of the generated energy are presented.

Numerical simulation of fractional-order Duffing system with extended Mittag-Leffler derivatives

In this paper, we studied the dynamics of a nonlinear fractional-order Duffing system combined with Mittag-Leffler derivatives in order to provide dynamic behaviors different from existing ones. The Mittag-Leffler derivative is a generalized version of the exponential kernel derivative. To achieve this goal, we introduced a modified extension to higher-order Mittag-Leffler derivatives to overcome the initialization problem. Moreover, we discussed some properties and relationships of the studied derivatives. Then we presented numerical schemes to handle fractional extensions of the considered oscillatory system including the Mittag-Leffler and the Caputo derivatives. Numerical simulations are carried out and the resulting simulation dynamics of the studied fractional oscillatory system are compared.

Design and Simulations of Solar-Based Hydrogen Production System via Methane Decomposition

A solar-based hydrogen production system is analyzed and studied with the intention of optimizing the parameters involved in oil refining industry and the environment of the United Arab Emirates. Methane decomposition in molten salt media using a concentrated solar power system was adopted, since the temperature range required in the system design is achievable with this method. The System Advisor Model software was used in this study with three cases to optimize the system using the levelized cost of heat concept. In Case 1, a levelized cost of heat of 9.32 ¢/kWh was achieved using an optimized system with a CSP-RTUVR-2014 receiver and a Luz LS-3 collector. The design of Cases 1 and 2 exhibited pressure drops along the system of just 10 bar, significantly lower than the 50 bar of Case 3. Similarly, designs of Cases 1 and 2 resulted in maximum receiver thermal losses of around 7 MW, whereas Case 3 yielded 14 MW loss. Analysis of the best-suited molten salt option showed that HITEC solar salt was better than HITEC XL and standard HITEC. A regression analysis was carried out to examine the pressure drop responses since it is a key variable affecting the integrity of the solar system. It was observed that the receiver mass flow rate is the main contributing cause of pressure drop. Through careful operator control of receiver mass flow rate, premature failures of the solar system caused by the pressure drop can be avoided.

Prognostics and Health Management of Unmanned Surface Vessels: Past, Present, and Future

Abstract With the increasing popularity and deployment of unmanned surface vessels (USVs) all over the world, prognostics and health management (PHM) has become an indispensable tool for health monitoring, fault diagnosis, health prognosis, and maintenance of marine equipment on USVs. USVs are designed to undertake critical and extended missions, often in extreme conditions, without human intervention. This makes the USVs susceptible to equipment malfunction, which increases the probability of system failure during mission execution. In fact, in the absence of any crew onboard, system failure during a mission can create a great inconvenience for the concerned stakeholders, which compels them to design highly reliable USVs that must have integrated intelligent PHM systems onboard. To improve mission reliability and health management of USVs, researchers have been investigating and proposing PHM-based tools or frameworks that are claimed to operate in real time. This paper presents a comprehensive review of the existing literature on recent developments in PHM-related studies in the context of USVs. It covers a broad perspective of PHM on USVs, including system simulation, sensor data, data assimilation, data fusion, advancements in diagnosis and prognosis studies, and health management. After reviewing the literature, this study summarizes the lessons learned, identifies current gaps, and proposes a new system-level framework for developing a hybrid (offline–online) optimization-based PHM system for USVs in order to overcome some of the existing challenges.

Effects on the design of aeronautical fuel cell systems by inclusion of reliability requirements

AbstractThe change towards carbon neutrality in air traffic involves a huge reduction of greenhouse gas emissions. This goal is beyond reach by the step wise improvement of conventional technologies. Hence, at present a solution which gains much of attraction are electric motors and electric aircraft systems in combination with fuel cells which can be run by green hydrogen. For a holistic comparison of various concepts the consideration of reliability aspects is required even at an early stage of design. In the scope of this work methods from reliability and safety engineering will be introduced and set in context of aeronautical fuel cell systems. On that basis the consequences arising by the requirement of redundancy are investigated on a system level approach. For this purpose, a model of an aeronautical fuel cell system will be set up in order to simulate a generic flight envelope at stationary points. The fuel cell system is chosen to be central-monolithic and its components are sized for the propulsion of a regional aircraft. With the aid of the system simulation, various failure scenarios are investigated from which mitigation strategies can be derived. Finally, the baseline design will be improved in terms of redundancy in order to last in a generic failure scenario. A comparison between the baseline and improved design shows that the additional redundancy comes with the cost of 4.6% weight increase and a 2.5% drop in cruise efficiency.

Teaching design and implementation of traffic system simulation course based on a computer virtual reality software under the background of engineering education

AbstractThe further reform and development of engineering education courses can help improve the teaching quality of higher education institutions, implement the fundamental task of talent cultivation, and provide important support and channels for cultivating high‐quality and supportive engineering technical talents. The traffic system simulation course is an applied science closely related to engineering technology. It mainly cultivates senior engineering technical talents engaged in research and development of transportation engineering, analysis of road traffic characteristics, and transportation planning and design. Considering the characteristics of the traffic system simulation course, this study puts forward the course teaching design based on computer virtual reality software. Combined with the training objectives of applied talents in the traffic system simulation course, this study focuses on how to reform the teaching content and teaching mode with the help of Vissim computer simulation software. The course teaching design refines and optimizes the teaching content by the use of computer software. The use of Vissim software in the course enriches the teaching content and methods and stimulates students' interest in learning. Through the guidance of active exploration and self‐directed learning for students, the traffic system simulation course reform has created a more positive and effective learning environment for students, which helps to cultivate their exploratory spirit and innovative ability. The implementation of the course teaching reform has gradually improved students' learning initiative and ability to master course content, as well as their practical problem‐solving abilities. Good teaching results have been achieved.

Learning Sea Surface Height Interpolation From Multi‐Variate Simulated Satellite Observations

AbstractSatellite‐based remote sensing missions have revolutionized our understanding of the Ocean state and dynamics. Among them, space‐borne altimetry provides valuable Sea Surface Height (SSH) measurements, used to estimate surface geostrophic currents. Due to the sensor technology employed, important gaps occur in SSH observations. Complete SSH maps are produced using linear Optimal Interpolations (OI) such as the widely used Data Unification and Altimeter Combination System (duacs). On the other hand, Sea Surface Temperature (SST) products have much higher data coverage and SST is physically linked to geostrophic currents through advection. We propose a new multi‐variate Observing System Simulation Experiment (OSSE) emulating 20 years of SSH and SST satellite observations. We train an Attention‐Based Encoder‐Decoder deep learning network (abed) on this data, comparing two settings: one with access to ground truth during training and one without. On our OSSE, we compare abed reconstructions when trained using either supervised or unsupervised loss functions, with or without SST information. We evaluate the SSH interpolations in terms of eddy detection. We also introduce a new way to transfer the learning from simulation to observations: supervised pre‐training on our OSSE followed by unsupervised fine‐tuning on satellite data. Based on real SSH observations from the Ocean Data Challenge 2021, we find that this learning strategy, combined with the use of SST, decreases the root mean squared error by 24% compared to OI.

Modelling environmental life cycle performance of alternative marine power configurations with an integrated experimental assessment approach: A case study of an inland passenger barge

There is pressure on the global shipping industry to move towards greener propulsion and fuel technologies to reduce greenhouse gas emissions. Hydrogen and electricity are both recognised as pathways to achieve a net-zero. However, in the evaluation of the environmental performance of these alternative marine power configurations, conventional life cycle assessment (LCA) methods have limitations reflecting the varied nature of ship design and operational modes. The integration of LCA with experimental assessment could remedy the shortcoming of conventional approaches to data generation. The system energy demand data in this study was generated based on specific ship design and directly fed into life cycle assessment. To demonstrate the effectiveness and potential the approach was applied to a case study of inland waterway vessel. Suitable hybrid PV/electricity/diesel and hydrogen powered fuel cell systems for the case vessel were modelled; and hydrodynamic testing and dynamic system simulation was undertaken to provide ship performance data under various operational/environmental profiles. Lifecycle assessment (LCA) indicated hydrogen and electrical propulsion technologies have the potential for 85.7 % and 56.2 % emissions reduction against an MGO base case, respectively. The results highlight that implementation of both technologies is highly dependent on energy production pathways. Hydrogen systems reliant on fossil feedstocks risk an increase in emissions of up to 6.3 % against the MGO base case. Sensitivity analysis indicated an electrical system with electricity production from 79.5 % renewables could achieve savings of 82.2 % in GHG emissions compared to the MGO base case. Crucially, the results demonstrate a further development of the LCA approach which can enable a more accurate environmental performance evaluation of alternative marine power configurations considering specific ship design and operational characteristics. Ultimately this addition makes the results more meaningful for commercial operations and decision making in the selection of alternative marine power systems to support the transition to net-zero.

CHBMLI based DSTATCOM for power quality improvemt in a three-phase three-wire distribution system with PI controller

This paper presents a cascaded h-bridge (CHB) multilevel inverter (MLI) based MLI based distribution static synchronous compensator (DSTATCOM). The main objective of this paper is to reduce source current harmonics in the distribution system by using a cascade H-bridge multilevel inverter (CHBMLI) as DSTATCOM with a proportional-integral (PI) controller. The PI controller compensates reactive power, reduces source current harmonics, and maintains the unity power factor in the distribution system. The conventional two-level inverter-based DSTATCOM has many disadvantages such as high total harmonic distortion (THD), and high switching stress power semi-conductor devices, suitable for only low-power applications. This paper to overcome these drawbacks by using MLI-based DSTATCOM. The proposed system simulations are verified in MATLAB/Simulink software. The verified results are source current, load current, and compensating current.

Performance evaluation of underground thermal storage integrated dual-source heat pump systems

The increasing demand for electricity stresses the existing electric grids. Buildings consume 73% of all U.S. electricity and are responsible for 30% of U.S. greenhouse gas emissions. Integrating thermal energy storage (TES) in building heating/cooling systems, which consume considerable electricity, can mitigate the challenges to electric grids. This study reports on a novel thermal energy storage device integrated heat pump system to reshape the building electricity demand profile while maintaining thermal comfort. The annual performance of the proposed system has been evaluated through a dynamic system simulation with high fidelity in the Modelica platform. The dynamic model of the novel hybrid component named ‘dual purpose underground thermal battery’ was developed and validated. It was then incorporated into the system model. Given a time-of-use tariff, a rule-based control strategy was designed to shift the electric demand and switch the heat pump source for a typical single-family house in different climate zones of the United States. The system performance of the new TES-integrated dual-source heat pump was compared with that of a conventional air-source heat pump system. The results indicate that the proposed system can reduce the annual HVAC electricity cost by up to 52% while saving 45.2% on electricity consumption. In the Northern areas, the annual peak load of the HVAC system can be reduced by 64.9%. However, this reduction is less in the Southern areas as the system’s higher efficiency in winter dominates the overall energy-saving potential.

Observing System Simulation Experiments (OSSEs) in Support of Next-Generation NOAA Satellite Constellation

Abstract Between 2014 and 2018, the National Oceanic and Atmospheric Administration conducted the NOAA Satellite Observing System Architecture (NSOSA) study to plan for the next generation of operational environmental satellites. The study generated some important questions that could be addressed by observing system simulation experiments (OSSEs). This paper describes a series of OSSEs in which benefits to numerical weather prediction from existing observing systems are combined with enhancements from potential future capabilities. Assessments include the relative value of the quantity of different types of thermodynamic soundings for global numerical weather applications. We compare the relative impact of several sounding configuration scenarios for infrared (IR), microwave (MW), and radio occultation (RO) observing capabilities. The main results are 1) increasing the revisit rate for satellite radiance soundings produces the largest benefits but at a significant cost by requiring an increase in the number of polar-orbiting satellites from 2 to 12; 2) a large positive impact is found when the number of RO soundings per day is increased well beyond current values and other observations are held at current levels of performance; 3) RO can be used as a mitigation strategy for lower MW/IR sounding revisit rates, particularly in the tropics; and 4) smaller benefits result from increasing the horizontal resolution along the track of the satellites of MW/IR satellite radiances. Furthermore, disaggregating IR and MW instruments into six evenly distributed sun-synchronous orbits is slightly more beneficial than when the same instruments are combined and collocated on three separate orbits.

Path planning of mobile robot based on improved TD3 algorithm in dynamic environment

This paper proposes an improved TD3 (Twin Delayed Deep Deterministic Policy Gradient) algorithm to address the flaws of low success rate and slow training speed, when using the original TD3 algorithm in mobile robot path planning in dynamic environment. Firstly, prioritized experience replay and transfer learning are introduced to enhance the learning efficiency, where the probability of beneficial experiences being sampled in the experience pool is increased, and the pre-trained model is applied in an obstacle-free environment as the initial model for training in a dynamic environment. Secondly, dynamic delay update strategy is devised and OU noise is added to improve the success rate of path planning, where the probability of missing high-quality value estimate is reduced through changing the delay update interval dynamically, and the correlated exploration of the mobile robot inertial navigation system in the dynamic environment is temporally improved. The algorithm is tested by simulation where the Turtlebot3 robot model as a training object, the ROS melodic operating system and Gazebo simulation software as an experimental environment. Meanwhile, the result shows that the improved TD3 algorithm has a 16.6 % increase in success rate and a 23.5 % reduction in algorithm training time. A generalization experiment was designed finally, and it indicates that superior generation performance has been acquired in mobile robot path planning with continuous action spaces through the improved TD3 algorithm.

The long term price elastic demand of hydrogen – A multi-model analysis for Germany

Hydrogen and its derivatives are important components to achieve climate policy goals, especially in terms of greenhouse gas neutrality. There is an ongoing controversial debate about the applications in which hydrogen and its derivatives should be used and to what extent. Typically, the estimation of hydrogen demand relies on scenario-based analyses with varying underlying assumptions and targets. This study establishes a new framework consisting of existing energy system simulation and optimisation models in order to assess the long-term price-elastic demand of hydrogen. The aim of this work is to shift towards an analysis of the hydrogen demand that is primarily driven by its price. This is done for the case of Germany because of the expected high hydrogen demand for the years 2025–2045. 15 wholesale price pathways were established, with final prices in 2045 between 56 €/MWh and 182 €/MWh. The results suggest that – if climate targets are to be achieved - even with high hydrogen prices (252 €/MWh in 2030 and 182 €/MWh in 2045) a significant hydrogen demand in the industry sector and the energy conversion sector is expected to emerge (318 TWh). Furthermore, the energy conversion sector has a large share of price sensitive hydrogen demand and therefore its demand strongly increases with lower prices. The road transportation sector will only play a small role in terms of hydrogen demand, if prices are low. In the decentralised heating for buildings no relevant demand will be seen over the considered price ranges, whereas the centralised supply of heat via heat grids increases as prices fall.

Hybrid minigrid system comprising energy storage systems with optimal frequency control empowering the new Egypt large optical telescope site

Proposed hybrid minigrid two area system simulation model encompassing Photo Voltaic (PV) system, Wind Turbines (WT), diesel generators and Energy Storage Systems with intelligent based optimal Frequency Controllers (FCs) empowering the new Egypt large optical telescope (ELOT) site is presented in this research. Technical study and specifications for a PV solar system of 1000 Kw is introduced. Intelligent fine optimized Proportional Integral Derivative (PID) and Fuzzy self-tuned PID (FSTPID) controllers are designed through applying Harris Hawk optimizer (HHO). The proposed HHO employed method performance is validated under number of eventualities which include vacillations of load, sun radiation and wind speed. The objective function and control parameters are the integral time summation of absolute deviations and the parameters of controllers, consecutively. The system dynamic response and simulation results show that the proposed HHO based FSTPID type FCs are effective in reducing frequency and tie line power signals’ deviations in a diminutive time for such minigrid hybrid system. For supplemental validations, simulation results obtained are compared with genetic algorithm to get the proposed controllers’ gains.

Tripartite Coordinated Governance Evolutionary Game and System Simulation Study on the Ecological Environment in China's Pearl River Basin

Tripartite Coordinated Governance Evolutionary Game and System Simulation Study on the Ecological Environment in China's Pearl River Basin

A solar diffusion-absorption refrigeration system for off-grid cold-chain provision, Part II: System simulation and assessment of performance

The diffusion-absorption refrigerator (DAR) is a cooling technology that can be driven entirely by thermal energy. With solar-thermal collectors as the heat source, this technology can provide a zero-emissions solution for essential cold-chain provision in the world’s poorest regions. In the accompanying paper, a system model of a solar-driven DAR system was developed for simulating operation under variable solar conditions. In Part II of this study, we apply this model to assess the predicted performance of the system in its intended application: for on-farm refrigeration of harvested crops in rural India. The roles of the working-fluid charge pressure and collector array area for maximum cooling are investigated. A charge pressure of 16 bar is found to be optimal for ambient conditions during the October harvest season in Ahmedabad, with a collector-array area of 1.5 m2 found to be most appropriate for the nominal 70 W cooling-capacity system. However, the time taken to reach the required solar collector temperature for bubble pump activation results in a daily operating period of less than 5 h and a predicted overall solar-to-cooling efficiency of less than 1%. To address these limitations, modifications to various components are considered based on simple assumptions for improving performance.

Beam loss detection based on generation of Cherenkov light in optical fibers in the CERN Linear Electron Accelerator for Research

Cherenkov optical beam loss monitors (oBLMs) based on optical fibers are a revolutionary achievement among the monitoring systems in particle accelerators. Due to the nature of the Cherenkov phenomenon and the intrinsic characteristics of optical fibers, the photon production and fiber light transmission need to be studied to deduce the total amount of Cherenkov photons detected by the photosensors attached at the end of the system. Simulations of the Cherenkov oBLM detector system have been implemented using the software with postprocessing considering the light attenuation and capture factors in the optical fiber. In addition, the study includes the longitudinal beam loss localization of the controlled beam losses produced along the CERN Linear Electron Accelerator for Research (CLEAR) test facility line. In this paper, the Cherenkov photon detection by an oBLM installed in the CLEAR facility is simulated, analyzed, and compared with experimental data. Published by the American Physical Society 2024

Hybrid stabilization of nonlinear systems based on a fully actuated system approach

This article studies the stabilization problem for a category of nonlinear systems. It introduces a novel hybrid control strategy specifically for nonlinear high-order fully actuated (HOFA) systems. The stabilization problem for these nonlinear HOFA systems is transformed into a stabilization problem for impulsive switched systems. This issue is addressed by applying impulsive control in discrete-time and switching control based on the HOFA system approach in continuous-time. Using switched Lyapunov functions, we obtain the criteria for the exponential and asymptotic stabilization of these systems. The effectiveness of this newly presented hybrid control strategy is exemplified by simulations of a robotic manipulator system and a reduced model of the lac operon.

Algorithm for steady contaminant distribution in ventilation systems with air recirculation: Contaminant release in ventilation ducts

When contaminants are released naturally or deliberately in ventilation ducts, they can contaminate the supply air and rooms through the return air recirculation of the ventilation and air conditioning system. Few studies have considered the impact of contaminant transport through air recirculation on the non-uniform indoor contaminant distribution. In this study, a method for calculating the steady-state contaminant distribution in a ventilation system with air recirculation when there is a contaminant release from the ventilation duct is presented. The ventilation ducts are considered as a virtual room and modelled separately from the rooms, both using linear superposition expressions based on accessibility indicators to obtain a relationship between contaminant concentrations at the outlet and inlet. A total of four sub-methods are proposed considering different treatments for the return and supply air ducts connected to each air handling unit (AHU). The proposed methods (Methods 1–3) considering the non-uniform characteristics of the ducts are shown to have an accuracy comparable to that of CFD (computational fluid dynamics) simulations, with an average prediction deviation of less than 5%, whereas the use of well-mixed assumption in the ducts (Method 4) results in an average prediction deviation of up to 45% in one of the rooms when the contaminant source is close to the diversion position of the supply air duct. The proposed method avoids the need for holistic modelling and iterative simulation of complex ventilation and air-conditioning system and multiple rooms, and allows for rapid prediction of contaminant distribution.

Design & Simulation of an Intelligent Energy Management System for Electric Vehicle Charging Stations

The transition towards electric vehicles (EVs) necessitates the development of efficient and reliable charging infrastructure. This paper presents the design and simulation of an EV charging station using MATLAB/Simulink. The proposed charging station incorporates both wired and wireless charging capabilities, aiming to provide a comprehensive solution that meets the diverse needs of EV users. The design process involves creating detailed models of the charging station components, including the power electronics for AC/DC conversion, wireless power transfer modules, and control systems for charge management. The MATLAB/Simulink environment offers robust tools for modeling and simulating these components, allowing for thorough analysis and optimization. Simulation results demonstrate the effectiveness of the charging station design in terms of efficiency, power management, and user convenience. The wired charging system is modeled to ensure compliance with standard charging protocols, optimizing the power flow to achieve minimal charging times while maintaining safety and reliability. The wireless charging system, based on inductive power transfer principles, is evaluated for its alignment sensitivity, power transfer efficiency, and interoperability with different vehicle models. Key performance metrics such as charging efficiency, power quality, and thermal performance are analyzed under various operating conditions. The simulation results indicate that the proposed design can achieve high efficiency and reliable operation, with wireless charging efficiencies exceeding 90% under optimal alignment conditions. Keywords: METLAB, Simulink, AC-DC, Simulation, Wireless Charging etc.