Simulation Model System Research Articles

A study on finite-time particle swarm optimization as a system identification method

The performance as a system identification technique of a variant of the particle swarm optimization (PSO) algorithm named finite-time particle swarm optimization (FPSO) was studied. First, this method was compared to several system identification algorithms by using data from a simulated linear system model. Special attention was given to their performance when the data from which they estimate the parameters of the system contain measurement noise. Afterwards, the effectiveness of FPSO in estimating the parameters of nonlinear systems was evaluated, using both data from simulations and data obtained from a real system with nonlinear behavior. The FPSO algorithm showed excellent performance when estimating the parameters of the simulated linear and nonlinear systems, both with noisy and noiseless data. Results from the parameter estimation of the real system showed more variation in the results of the algorithm; however, simulations using the estimated parameters were still able to closely emulate the real system.

Timescale‐dependent AMOC–AMO relationship in an earth system model of intermediate complexity

AbstractThe relationship between Atlantic multi‐decadal oscillation (AMO) and Atlantic meridional overturning circulation (AMOC) is examined with respect to two (inter‐ and multi‐decadal) different timescales using a long‐term unforced simulation of an earth system model of intermediate complexity. In the inter‐decadal timescale, the AMO and the AMOC establish a self‐sustaining oscillatory mode; the AMOC induces the positive AMO through meridional heat transport (MHT), but with the time delay of approximately 7 years as the AMOC anomalies propagate southward over time within the Atlantic basin. After then, the AMO reduces the density in the main sinking region and brings the negative phase of the AMOC, which results in the rest half of the cycle. On the other hand, in the multi‐decadal timescale, the AMO and the AMOC are almost in phase because the AMOC is spatially stationary, resulting in a pan‐Atlantic surface warming. In addition, the Arctic‐originated density fluctuations are required for the multi‐decadal AMOC to switch its phase. The results obtained in this study suggest that timescale dependency should be considered when investigating the AMOC–AMO relationship.

Modelling and simulation of sprinters’ health promotion strategy based on sports biomechanics

With the rapid development of the new edge discipline sports biomechanics, modelling and simulation of human motion as one of the cutting-edge research topics in sports biomechanics is receiving more and more attention. Based on the establishment of the three-dimensional simulation system model of human knee joint and the analysis of buckling motion, this paper uses the three-dimensional image registration knee joint motion analysis method to carry out the research on knee flexion movement to solve the knee joint injury problem of sprinters. The results showed that medial collateral ligament injury and meniscus injury were more common in all types of knee joint injuries, accounting for 24% respectively 7% and 22.4%. The incidence of lateral collateral ligament injury was relatively small, accounting for only 5.6%. And the research shows that the foot strength curve recognition method based on biomechanics sprinters knee joint simulation model is an advanced and complete strategy to reduce sprinters knee joint injury, and it can achieve better results in sprinters knee joint nursing.

Spectrum handoff analysis for multiple secondary users in cognitive radio networks

<p>The cognitive radio network permits secondary users to reach unused spectrum of primary users. In this paper, a mixed preemptive/non-preemptive resume priority M/G/1 queuing model is proposed for characterizing multiple handoff delay and to minimize the extended data delivery time of secondary users that has experienced multiple spectrum handoff during its transmission. The proposed queuing model supports delay-sensitive secondary user applications. The secondary users’ traffic is classified into two priority classes, the highest priority class for delay sensitive services and the lowest priority class for delay insensitive services. Furthermore, the proposed model assigns higher priority for the interrupted secondary users over uninterrupted secondary users for each class of secondary users in order to minimize the handoff delays for secondary users that experience multiple interruptions. Analytical formulas for the average extended data delivery time are derived for two different proactive spectrum handoff strategies (always stay and always change strategies) for both classes of secondary users. Simulation of proposed system model was performed to validate the analytical results and a good agreement was obtained. The performance of the suggested model is assessed and compared with other spectrum handoff models. Numerical results illustrate that the proposed system model outperforms existing models and can reduce the extended data delivery time for the secondary users.</p>

Increase in ocean acidity variability and extremes under increasing atmospheric CO<sub>2</sub>

Abstract. Ocean acidity extreme events are short-term periods of relatively high [H+] concentrations. The uptake of anthropogenic CO2 emissions by the ocean is expected to lead to more frequent and intense ocean acidity extreme events, not only due to changes in the long-term mean but also due to changes in short-term variability. Here, we use daily mean output from a five-member ensemble simulation of a comprehensive Earth system model under low- and high-CO2-emission scenarios to quantify historical and future changes in ocean acidity extreme events. When defining extremes relative to a fixed preindustrial baseline, the projected increase in mean [H+] causes the entire surface ocean to reach a near-permanent acidity extreme state by 2030 under both the low- and high-CO2-emission scenarios. When defining extremes relative to a shifting baseline (i.e., neglecting the changes in mean [H+]), ocean acidity extremes are also projected to increase because of the simulated increase in [H+] variability; e.g., the number of days with extremely high surface [H+] conditions is projected to increase by a factor of 14 by the end of the 21st century under the high-CO2-emission scenario relative to preindustrial levels. Furthermore, the duration of individual extreme events is projected to triple, and the maximal intensity and the volume extent in the upper 200 m are projected to quintuple. Similar changes are projected in the thermocline. Under the low-emission scenario, the increases in ocean acidity extreme-event characteristics are substantially reduced. At the surface, the increases in [H+] variability are mainly driven by increases in [H+] seasonality, whereas changes in thermocline [H+] variability are more influenced by interannual variability. Increases in [H+] variability arise predominantly from increases in the sensitivity of [H+] to variations in its drivers (i.e., carbon, alkalinity, and temperature) due to the increase in oceanic anthropogenic carbon. The projected increase in [H+] variability and extremes may enhance the risk of detrimental impacts on marine organisms, especially for those that are adapted to a more stable environment.

CONSTRUCTION OF A SIMULATION MODEL OF MANAGEMENT OF INTERNAL COMMODITY FLOWS OF PHARMACY NETWORKS

Purpose. The aim of the article is to develop a simulation model of internal product flow management processes of pharmacy networks. Methodology of research. The theoretical basis for building a system and dynamic model of flow control in the logistics system of the pharmacy network are scientific articles by domestic and foreign scientists on the problems of management of logistics and flow of pharmaceutical companies and pharmacy networks. The following research methods are used to achieve this goal: analysis and synthesis (in the study of the theoretical foundations of the formation of logistics systems of pharmacy networks); economic and mathematical modelling (to optimize the management of domestic commodity flows). Findings. A simulation system and dynamic model of product flow management of the logistics system of the pharmacy network in conditions of demand uncertainty has been developed, in particular: 1) the input variables and parameters of the commodity flow management model in the logistics system of the pharmacy network are studied, the limitations and conditions of its application are formed; 2) a system of difference equations of levels, rates and auxiliary variables of the model is developed. Originality. Scientific and methodological approach to the management of commodity flows of logistics systems of pharmacy networks in terms of random demand is improved on the basis of a simulation model of system dynamics. It includes a sub-model of commodity flows and a sub-model of accounting for logistics costs, the implementation of which within the mechanism of management of commodity flows of logistics systems of pharmacy networks allows to simplify the process of analysis and management of the pharmacy network management decisions of operational and tactical nature. Practical value. The results of the study can be applied in practical activities of pharmacy networks in order to increase the efficiency of formation and operation of their logistics systems. Key words: commodity flow management, logistics systems of pharmacy networks, optimization, modelling.

Rugalmas gyártórendszer hatékonyságának növelése dolgozói képességek szimulációjára alapozott termeléstervezési módszerrel

In addition to the spread of Industry 4.0 and various digitization solutions, the human factor continues to play a key role in the operation of production and logistics processes. Therefore, development of digital models and calculation algorithms that are able to take into account the production capabilities of the employees in an integrated way during the production planning and the determination of the production sequences becomes necessary. Due to the complexity of the task, simulation models are often applied. Performance of production scheduling systems enhanced with employee capabilities can be effectively evaluated with such models. Our paper presents a general simulation system model and a new heuristic algorithm to support production scheduling. The simulation based investigation proved that the proposed method improves the efficiency of the studied production system in terms of resource utilization.

A typology of regional innovation ecosystem models

Subject. This article explores the economic and social relations regarding the formation and functioning of innovation ecosystems. Objectives. The article aims to develop a typology of models of regional innovation systems. Methods. For the study, we used a system logical analysis and simulation modeling. Results. The article presents an original typology of models of regional innovation ecosystems and basic tools for analyzing and modeling different ecosystems (classification criteria, groups). Conclusions. We propose to use these models for analytical developments, design, and description of various examples of the subject of research in the real world, in the activities of a wide range of socio-economic and political actors both within ecosystems and influencing their genesis from the outside.

Інтелектуальна навчальна система підготовки диспетчерів управління повітряним рухом

В статті розглянуті основні методи організації інтелектуального навчального середовища підготовки диспетчерів управління повітряним рухом. Обґрунтована необхідність створення інтелектуальної навчальної системи в адаптивних тренажерах диспетчерів управління повітряним рухом. Інтелектуальні навчальні системи повинні базуватись на основі синтезу імітаційно-моделюючих комплексів у вигляді розподілених систем обробки даних для імітації поведінки середовища навчання. В роботі сформовані вимоги, що висуваються до побудови мультиагентного середовища інтелектуальної навчальної системи підготовки диспетчерів управління повітряним рухом. З метою забезпечення моделювання інтелектуального поводження об'єктів, що входять у віртуальне середовище навчання, запропоновано створення інтелектуальних об'єктів, як елементів мультиагентної системи з використанням методів планування дій. Запропоновано підхід удосконалення та розширення функціональних можливостей системи підготовки диспетчерів управління повітряним рухом. Запропонована архітектура інтелектуального агента навчальної системи підготовки диспетчерів управління повітряним рухом створена на базі елементів InterRRa архітектури, що забезпечує взаємодію агента з зовнішнім середовищем та іншими агентами через модель фізичного представлення об'єкта. Наведена математична модель інтелектуального агента в якій враховано можливість здійснення впливу на зовнішнє середовище. Розроблена модель мультиагентного середовища інтелектуальної навчальної системи яка забезпечує ідентифікацію ситуації в підсистемі підготовки і прийняття рішень, що виконує передачу управління на відповідний рівень ієрархії системи поводження інтелектуального агента. Особливістю розробленої структури мультиагентного середовища інтелектуальної навчальної системи є використання моделі поведінки інтелектуальних агентів, що забезпечують змінну поведінку і можливість рішення задач підготовки і прийняття рішень своїх подальших дій за допомогою різних моделей поведінки.

Causal Interactions between Southern Ocean Polynyas and High-Latitude Atmosphere–Ocean Variability

AbstractWeddell Sea open-ocean polynyas have been observed to occasionally release heat from the deep ocean to the atmosphere, indicating that their sporadic appearances may be an important feature of high-latitude atmosphere–ocean variability. Yet, observations of the phenomenon are sparse and many standard-resolution models represent these features poorly, if at all. We use a fully coupled, synoptic-scale preindustrial control simulation of the Energy Exascale Earth System Model (E3SMv0-HR) to effectively simulate open-ocean polynyas and investigate their role in the climate system. Our approach employs statistical tests of Granger causality to diagnose local and remote drivers of, and responses to, polynya heat loss on interannual to decadal time scales. First, we find that polynya heat loss Granger causes a persistent increase in surface air temperature over the Weddell Sea, strengthening the local cyclonic wind circulation. Along with responding to polynyas, atmospheric conditions also facilitate their development. When the Southern Ocean experiences a rapid poleward shift in the circumpolar westerlies following a prolonged negative phase of the southern annular mode (SAM), Weddell Sea salinity increases, promoting density destratification and convection in the water column. Finally, we find that the reduction of surface heat fluxes during periods of full ice cover is not fully compensated by ocean heat transport into the high latitudes. This imbalance leads to a buildup of ocean heat content that supplies polynya heat loss. These results disentangle the complex, coupled climate processes that both enable the polynya’s existence and respond to it, providing insights to improve the representation of these highly episodic sea ice features in climate models.

An adaptive delay compensation method based on a discrete system model for real-time hybrid simulation

The identification of delays and delay compensation are critical problems in real-time hybrid simulations (RTHS). Conventional delay compensation methods are mostly based on the assumption of a constant delay. However, the system delay may vary during tests owing to the nonlinearity of the loading system and/or the behavioral variations of the specimen. To address this issue, this study presents an adaptive delay compensation method based on a discrete model of the loading system. In particular, the parameters of this discrete model are identified and updated online with the least-squares method to represent a servo hydraulic loading system. Furthermore, based on this model, the system delays are compensated for by generating system commands using the desired displacements, achieved displacements, and previous displacement commands. This method is more general than the existing compensation methods because it can predict commands based on multiple displacement categories. Moreover, this method is straightforward and suitable for implementation on digital signal processing boards because it relies solely on the displacements rather than on velocity and/or acceleration data. The virtual and real RTHS results show that the studied method exhibits satisfactory estimation smoothness and compensation accuracy. Furthermore, considering the measurement noise, the low-order parameter models of this method are more favorable than that the high-order parameter models.

A System Dynamics Modeling and Computer-based Simulation in Forecasting Long-term Sufficiency: A Philippine Chicken Meat Sector Case Study

As the human population continues to grow, the global growth of the livestock sector will continue to rise as well. In the Philippines, the demand for chicken meat is projected to triple by 2050. In this study, the increasing consumption and long-term sufficiency were evaluated with the use of the system dynamics concept. With system modeling and computer-based simulation techniques, the available data on chicken meat supply chain were processed considering that factors behave dynamically. The simulated model facilitated the forecasting of key variables which may drop sufficiency from 87% in 2015 to 60% by 2050 if no proper actions take place in the areas of production and consumption. As a whole, this study developed and demonstrated preliminary system dynamics-based and computer based-approaches in order to understand the chicken meat sector. This showed that a dynamic systems-based paradigm shift in food and agricultural systems analysis can help address operational and strategic issues regarding food security.

Properties Dynamic Simulation of the Flywheel Energy Storage System Model with Speed-Current Double Closed Loop

The random fluctuation of output power of modern distributed power generation system brings many hidden dangers to the safe operation of power grid, and the application of energy storage system is the most effective way to smooth the output power of distributed power generation. Based on the analysis of the structure and charge-discharge dynamic performance of the flywheel energy storage system, the permanent magnet brushless DC motor (PMBLDCM) is proposed as the flywheel motor, and the charging and discharging mathematical model of the flywheel energy storage system based on PMBLDCM is established. Using MATLAB/Simulink, the simulation model of flywheel energy storage system with speed-current double closed Loop is established. The simulation results show that the system can effectively control the flywheel energy storage system to achieve two-way energy conversion, and effectively stabilize power fluctuations.

Rotor Displacement Self-Sensing Modeling of Six-Pole Radial Hybrid Magnetic Bearing Using Improved Particle Swarm Optimization Support Vector Machine

An inverter-fed six-pole radial hybrid magnetic bearing (HMB) has the characteristics of compact structure, high support speed, long service life, and so on. However, using displacement sensors to detect rotor displacements leads to the problems of large volume, high cost, and low reliability. In this article, a self-sensing method using improved particle swarm optimization (IPSO) least square support vector machine (LS-SVM) is proposed, which eliminates the influences of displacement sensors fundamentally. The structure and working principle of six-pole radial HMB are introduced, and the mathematical model of its radial suspension force is deduced according to the equivalent magnetic circuit method. Based on the regression principle of the LS-SVM, the prediction model between the currents in control coils and the rotor displacements is established. Also, the performance parameters of LS-SVM are optimized by the IPSO algorithm, which realizes self-sensing modeling of rotor displacement. The simulation system for self-sensing modeling of rotor displacement for six-pole radial HMB is constructed, and floating experiment, static suspension experiment, dynamic suspension experiment, and disturbance experiment of the rotor are carried out, which verify the robustness and stability of the self-sensing method proposed.

Testing the WEAP Hydrologic Model for Awash Basin, Ethiopia “Soil Moisture Module with Watershed Demand Approach”

The research is financed by the Egyptian Government through the Nile Sector bilateral cooperation project Abstract Currently, there are several hydrological simulation models in use worldwide. Prior to adoption of a model to a specific basin, its feasibility and practicality should be tested. This study highlights on the application of Water Evaluation and Planning system (WEAP) model for hydrologic simulation of Awash river basin in Ethiopia. A monthly time step hydrologic model was developed using the soil moisture rainfall-runoff method incorporated in WEAP with an aim to check the suitability of the model for Awash river basin. For this purpose five selected flow gauge stations located at the upper, middle and lower Awash basin were used as control stations. The model is configured taking into account the effects of development and hence the water abstractions, storage, loss rate, etc. are estimated using the data provided through various kinds of research and survey in Ethiopia. Standard methods are also used to prepare the hydro-metrological and landuse input data for each sub-catchment. Based on data availability, the time period 1986-2005 was selected for the hydrologic simulation. The observed data were split for calibration (1986–1995) and validation (1996–2005) purposes. Initially, the model was set up using the default model parameters. Then, manual calibration is performed to reproduce the observed streamflow. The model-simulated values are compared with those obtained from observations using standard statistical tests on monthly and monthly average basis. From the performance test results, it is observed that the coefficient of determination (R 2 ) and the Index of Agreement (IA) show a good fit. Furthermore, the Nash-Sutcliffe Efficiency (NSE) and the Percent Bias (PBIAS) calibration and validation results show good performance for Upper Awash stations and satisfactory results for the middle and lower Awash control stations. As a conclusion, the main modelling constraints were discussed and possible solutions were also suggested in order to improve the performance of water resources simulation models for the Awash basin. Keywords : Awash Basin, Hydrologic Simulation, Calibration, Validation, Model Performance, WEAP DOI: 10.7176/CER/12-3-07 Publication date: March 31 st 2020

Establishment of Petrochemical Process Security Simulation and Emergency Drill Platform

The petrochemical process is universally featured in large production scale, long process and multiple procedures, which lead to high difficulty in security simulation system establishment for petrochemical process and formulation of emergency plan. This paper puts forward a construction method for security simulation system modeling platform for petrochemical process, and the platform could provide the function of emergency drill. The platform could rapidly build simulation model through mechanism modeling and data modeling, and apply knowledge graph technology and semantic feature matching method to automatically analyze different emergency plans to acquire formal definition of plan and realize automatic plan selection. Compared to traditional method, the platform proposed in this paper could simulate different accident scenes and acquire effective emergency plans, providing effective assistance for emergency disposal decision making.

Differences in physical habitat simulation system modelling results using benthic or pelagic fish species as indicators in Peruvian Andes–Amazon rivers

AbstractAquatic organisms with different adaptations are used as indicators in physical habitat simulation system models. Those adaptations are critical for determining the shape of the weighted usable area/width curve and for recommending values of environmental flows. The main objective of this study is to compare the use of benthic native species (Astroblepus taczanowskii and Astroblepus vanceae) versus the introduced Oncorhynchus mykiss (rainbow trout) as target indicators for PHABSIM modelling in the Andean–Amazon piedmont rivers. We used adjusted probability distribution functions with L‐moments analyses for developing curves of use and preference to evaluate the efficiency of each indicator. Two hydraulic modelling sections were established in the Ulcumayo River with 21 and 27 cross sections, respectively. Native benthic species are usually dominant but scarcely used as focus organisms for environmental flows modelling. These species are associated with fast running and shallow waters, which makes them potentially more sensitive to the effects of flow reduction. Our results indicated that the native species were more restricted to velocity and depth than O. mykiss. Using selection curves in PHABSIM modelling, it is required between 10% to 94% of the mean monthly flow to preserve 90% of the available habitat for Astroblepus during the dry season (May to November). In contrast, rainbow trout requires 5% to 88% of the mean monthly flow. We conclude that a multispecies approach is useful for determining the required environmental instream flows contributing to a better sustainable condition for the Neotropical mountain rivers.

Integrating Backlight With Color-Filter-Free Panel for Enhancing Performance of LCD

In this study, we proposed an innovative concept of integrating a polarized color-separating backlight with a color-filter-free LC panel for enhancing performance of the curved LCD system. We design a two-level folded backlight to exploit the light sources LEDs with color enhancement by quantum-dot technology to produce color beams emerging at separate angles with a linearly polarizing state. The integrated LC panel focuses the separating color beams onto the corresponding subpixels with no need of the color filter; redirects the color beams at respective angles into the normal and reforms their angular shapes to be identical for attaining good color uniformity in the viewing cone. We established a system model for simulation to evaluate its performance. According to the simulation results, it performs the high optical efficiency of 33.75% that is about four times the traditional LCD, and displays color gamut of 94.1% NTSC (CIE 1931). It also provides the illuminance uniformity of 90% above and good color uniformity in both the spatial space and angular space of the viewing cone with horizontal and vertical angular widths of 100o and 75o, respectively. Furthermore, the simulation results demonstrate that the design can apply to a 55-inch curved LCD and further extend the maximum diagonal size up to 88 inches while keeping slim volume with a minimal thickness of 6.5 mm.

Research on Damping Performance of Dual Mass Flywheel Based on Vehicle Transmission System Modeling and Multi-Condition Simulation

In this paper, the reduction of vibration of dual mass flywheel (DMF) torsional damper under multiple working conditions is studied. Firstly, a 6DOF non-linear transmission system model including engine, DMF, gear pair of gearbox and clutch friction model is established. Secondly, a comprehensive multi-condition simulation strategy including ignition condition, idle condition, startup condition, drive condition, uniform speed condition and coast condition is designed to study the vibration reduction performance of DMF under different conditions. Then, the accuracy of the 6DOF non-linear transmission system model is verified. The simulation and test results showed that the accuracy of the model meets the engineering requirements. Finally, the effects of the performance parameters of the DMF on the torsional vibration of the transmission system under various operation conditions are studied. The results show that the performance of DMFs varies significantly under different conditions, and under drive condition the DMF has the best performance of vibration reduction. The free angle has less impact on the damping performance of the DMF, but other parameters have greater influence. The influence trend of the same parameter on the vibration reduction performance of DMF is different under different working conditions. Therefore, the parameter matching of the DMF cannot be based on one driving condition. It is necessary to comprehensively consider the vibration damping performance of the vehicle powertrain under multi-condition to match the parameters.

Fault classification and location identification in a smart DN using ANN and AMI with real‐time data

This paper presents a real-time fault classification and location identification method for a smart distribution network (DN) using artificial neural networks (ANNs) and advanced metering infrastructure (AMI). It also describes the development of a testbed for real-time testing of the proposed approach. The testbed consists of a simulated power system model [running on a digital real-time simulator (DRTS)] and AMI. The core parts of AMI are smart meters (SMs), a communication network (developed using DNP3 protocol over transfer control protocol/Internet protocol), data concentrator (DC), and a Utility Operations Centre (UOC). Event-driven data from SMs are collected in the DC and then fed to the UOC for being used as inputs for the novel ANN-based fault classification and location identification algorithm. On the basis of the data received, the algorithm can classify the fault type and locate it with high accuracy. Both balanced and unbalanced fault types are tested on different nodes and lines throughout a DN modelled in offline and on the DRTS. A comprehensive sensitivity analysis is performed to validate the effectiveness of the proposed method. Classification accuracy of over 99% is achieved when classifying all fault types, and above 95% accuracy is achieved when identifying the fault location.