Big Data Application Simulation Platform Design for Onboard Distributed Processing of LEO Mega-Constellation Networks

Due to the restricted satellite payloads in LEO mega-constellation networks(LMCNs),remote sensing image analysis,online learning and other big data services desirably need onboard distributed processing(OBDP).In existing technologies,the efficiency of big data applications(BDAs)in distributed systems hinges on the stable-state and low-latency links between worker nodes.However,LMCNs with high-dynamic nodes and long-distance links can not provide the above conditions,which makes the performance of OBDP hard to be intuitively measured.To bridge this gap,a multidimensional simulation platform is indispensable that can simulate the network environment of LMCNs and put BDAs in it for performance testing.Using STK's APIs and parallel computing framework,we achieve real-time simulation for thousands of satellite nodes,which are mapped as application nodes through software defined network(SDN)and container technologies.We elaborate the architecture and mechanism of the simulation platform,and take the Starlink and Hadoop as realistic examples for simulations.The results indicate that LMCNs have dynamic end-to-end latency which fluctuates periodically with the constellation movement.Compared to ground data center networks(GDCNs),LMCNs deteriorate the computing and storage job throughput,which can be alleviated by the utilization of erasure codes and data flow scheduling of worker nodes.

Model simulation of thermal environment and energy effects of rooftop distributed photovoltaics

Rooftop distributed photovoltaic(DPV)systems show promise for alleviating the energy crisis resulting from summer urban cooling demands and mitigating secondary hazards associated with urban heat islands.In this study,a parametric scheme for rooftop DPVs was incorporated into the Weather,Research and Forecasting model.The period from August 12–16,2022,during a heatwave in Jiangsu Province,China,was selected as the weather background to simulate the impact of rooftop DPVs with varying power generation efficiencies on urban thermal environments and energy supply.The results indicate that(1)rooftop DPVs reduce urban air temperatures at 2 m by weakening the solar radiation reaching the surface.As solar panel efficiency improves,the cooling effects become more significant,particularly at night.Day and night air temperatures at 2 m can decrease by approximately 0.1°C–0.4°C and 0.2°C–0.7°C,respectively;(2)Installing rooftop DPVs can lower boundary layer temperatures,with pronounced cooling effects during the day(up to 0.7°C at 08:00)and night(up to 0.6°C at 20:00);(3)If all buildings are equipped with rooftop DPVs,the electricity generated could meet Jiangsu Province’s total electricity demand during heatwaves.With 30%generation efficiency and rooftop DPVs installed at 40%of buildings,the electricity produced can meet the entire electricity demand.

Distributed Computation Models for Data Fusion System Simulation

An attempt has been made to develop a distributed software infrastructure model for onboard data fusion system simulation, which is also applied to netted radar systems, onboard distributed detection systems and advanced C3I systems. Two architectures are provided and verified: one is based on pure TCP/IP protocol and C/S model, and implemented with Winsock, the other is based on CORBA (common object request broker architecture). The performance of data fusion simulation system, i.e. reliability, flexibility and scalability, is improved and enhanced by two models. The study of them makes valuable explore on incorporating the distributed computation concepts into radar system simulation techniques.

DISTRIBUTED SIMULATION SYSTEM BASED ON UNIVERSAL COMPONENTS

Based on MATRIXx, a universal real-time visual distributed simulation system is developed. The system can receive different input data from network or local terminal. Application models in the simulation modules can automatically get such data to be analyzed and calculated, and then produce real-time simulation control information. Meanwhile, this paper designs relevant simulation components to implement the input and output data, which can guarantee the real-time and universal of the data transmission. Result of the experimental system shows that the real-time performance of the simulation is perfect.

Molecular simulation study of the microstructures and properties of pyridinium ionic liquid[HPy][BF_(4)]mixed with acetonitrile

The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.

Application of DSAPSO Algorithm in Distribution Network Reconfiguration with Distributed Generation

With the current integration of distributed energy resources into the grid,the structure of distribution networks is becoming more complex.This complexity significantly expands the solution space in the optimization process for network reconstruction using intelligent algorithms.Consequently,traditional intelligent algorithms frequently encounter insufficient search accuracy and become trapped in local optima.To tackle this issue,a more advanced particle swarm optimization algorithm is proposed.To address the varying emphases at different stages of the optimization process,a dynamic strategy is implemented to regulate the social and self-learning factors.The Metropolis criterion is introduced into the simulated annealing algorithm to occasionally accept suboptimal solutions,thereby mitigating premature convergence in the population optimization process.The inertia weight is adjusted using the logistic mapping technique to maintain a balance between the algorithm’s global and local search abilities.The incorporation of the Pareto principle involves the consideration of network losses and voltage deviations as objective functions.A fuzzy membership function is employed for selecting the results.Simulation analysis is carried out on the restructuring of the distribution network,using the IEEE-33 node system and the IEEE-69 node system as examples,in conjunction with the integration of distributed energy resources.The findings demonstrate that,in comparison to other intelligent optimization algorithms,the proposed enhanced algorithm demonstrates a shorter convergence time and effectively reduces active power losses within the network.Furthermore,it enhances the amplitude of node voltages,thereby improving the stability of distribution network operations and power supply quality.Additionally,the algorithm exhibits a high level of generality and applicability.

Joint probability distribution of winds and waves from wave simulation of 20 years (1989-2008) in Bohai Bay

The joint probability distribution of wind speed and significant wave height in the Bohai Bay was investigated by comparing the Gurnbel logistic model, the Gumbel-Hougaard （GH） copula function, and the Clayton copula function. Twenty years of wind data from 1989 to 2008 were collected from the European Centre for Medium-Range Weather Forecasts （ECMWF） database and the blended wind data of the Quick Scatterometer （QSCAT） satellite data set and re-analysis data from the United States National Centers for Environmental Prediction （NCEP）. Several typhoons were taken into account and merged with the background wind fields from the ECMWF or QSCAT/NCEP database. The 20-year data of significant wave height were calculated with the unstructured-grid version of the third-generation wind wave model Simulating WAves Nearshore （SWAN） under extreme wind process conditions. The Gumbel distribution was used for univariate and marginal distributions. The distribution parameters were estimated with the method of L-moments. Based on the marginal distributions, the joint probability distributions, the associated return periods, and the conditional probability distributions were obtained. The GH copula function was found to be optimal according to the ordinary least squares （OLS） test. The results show that wind waves are the prevailing type of wave in the Bohai Bay.

Theory and Implementation of Distributed Visual Simulation

The development process as well as the core theory of distributed interactive simulation and high level architecture are discussed, and combined with graphics features, a system of real time distributed visual simulation is established. Based on computer network, simulation platform is built by installing related software and modeling object, and the interactive functions are extended by programming. A set of solutions for building a distributed visual simulation system that include both hardware and software are put forward, and a practical instance is also provided. The whole building process can be summarized into two steps that are scheme consideration and system realization.

Integration of naval distributed tactical training simulation system based on advanced message queuing protocol

Aiming at the problems of unreliable data transmission,poor steadiness,nonsupport of complex data types,direct couple between data transmission and exchange,a high-level method based on advanced message queuing protocol( AMQP) is proposed to integrate naval distributed tactical training simulation system after serious consideration with current information exchange features of military combat system. Transferring layer in traditional user datagram protocol is implemented by publishing and subscribing scheme of message middleware. By creating message model to standardize message structure,integration architecture is formulated to resolve potential information security risks from inconsistent data type and express data transmission. Meanwhile,a communication model is put forward based on AMQP,which is in the center position of the whole transmission framework and responsible for reliably transferring battlefield data among subsystems. Experiments show that the method can accurately post amounts of data to the subscriber without error and loss,and can get excellent real-time performance of data exchange.

Simulation of a class of delay stochastic system with distributed parameter

Simulation of a class of delay stochastic system with distributed parameter is discussed. Difference schemes for the numerical computation of delay stochastic system are obtained. The precision of the difference scheme and the efficiency of the difference scheme in simulation of delay stochastic system with distributed parameter are analyzed. Examples are given to illustrate the application of the method.

Hierarchical Distributed Control Design for Multi-agent Systems Using Approximate Simulation

在这份报纸，我们基于近似模拟为多代理人系统考虑一个层次控制图案。到还原剂复杂性，我们首先构造一个简单抽象系统指导代理人，然后，我们讨论在抽象系统和多重代理人之间的模拟关系。在这个抽象系统的帮助下，分布式的层次控制被建议完成一项协作任务。由普通 Lyapunov 功能的优点，我们与考虑到模拟功能交换多代理人拓扑学分析集体行为。

New Solution on Distributed Hardware-in-the-Loop Radar System Simulation on HLA

In the large-scale distributed hardware-in-the-loop radar simulation system based on HLA, a new solution of processing after acquisition is proposed, which separates the software subsystem from the hardware jammer subsystem by a response database, so as to settle the problem, that the software subsystem can not meet the real-time need of the hardware, with very little increment of code. And the data completeness and feasibility of this solution are discussed.

Dynamic Multicast Grouping Approach in HLA-Based Distributed Interactive Simulation

In order to improve the efficiency of data distributed management service in distributed interactive simulation based on high level architecture (HLA) and to reduce the network traffic and save the system resource, the approaches of multicast grouping in HLA-based distributed interactive simulation are discussed. Then a new dynamic multicast grouping approach is proposed. This approach is based on the current publication and subscription region in the process of simulation. The results of simulation experiment show that this approach can significantly reduce the message overhead and use fewer multicast groups.

Simulation on Single Server &Distributed Environment (It’s Comparison &Issues)

Simulation has become the evaluation method of choice for many areas of distributing computing research. Simulation has been applied successfully for modeling small and large complex systems and understanding their behavior, especially in the area of distributed systems or parallel environment. The aim of my research is to study and qualitative analysis of simulation on a single server & on distributed environment and finding the related issues & its comparison.

MCloudSim:modeling and simulating distributed clouds

Many distributed clouds which try to integrate the advantages of centralized clouds and distributed systems have been studied in recent years.Traditional cloud simulators focus on large scale data centers with virtualized servers,and cannot meet the needs of distributed cloud simulations.This paper introduces a generalized and extensible simulation framework,named MCloudSim,which is used for modeling and simulating distributed clouds.MCloudSim has the following characteristics;(1)the overlay protocol in MCloudSim can be freely replaced without affecting the function of other modules;(2) a Petri net workflow theory based task model is proposed to simulate distributed tasks;(3) a distributed cloud can be easily built by assembling and expanding the basic resource entities provided by MCloudSim.Finally,simulation results of scenarios with a 3-tier central-controlled distributed cloud and a P2 P based cloud prove that MCloudSim has high efficiency and satisfies performance in supporting large scale experiments and different distributed clouds.

Application of Spatially Distributed Calibrated Hydrological Model in Evapotranspiration Simulation of Three Gorges Reservoir Area of China:A Case Study in the Madu River Basin

Evapotranspiration(ET)is the key to the water cycle process and an important factor for studying near-surface water and heat balance.Accurately estimating ET is significant for hydrology,meteorology,ecology,agriculture,etc..This paper simulates ET in the Madu River Basin of Three Gorges Reservoir Area of China during 2009-2018 based on the Soil and Water Assessment Tool(SWAT)model,which was calibrated and validated using the MODIS(Moderate-resolution Imaging Spectroradiometer)/Terra Net ET 8-Day L4 Global 500 m SIN Grid(MOD16A2)dataset and measured ET.Two calibration strategies(lumped calibration(LC)and spatially distributed calibration(SDC))were used.The basin was divided into 34 sub-basins,and the coefficient of determination(R^(2))and NashSutcliffe efficiency coefficient(NSE)of each sub-basin were greater than 0.6 in both the calibration and validation periods.The R2 and NSE were higher in the validation period than those in the calibration period.Compared with the measured ET,the accuracy of the model on the daily scale is:R^(2)=0.704 and NSE=0.759(SDC results).The model simulation accuracy of LC and SDC for the sub-basin scale was R^(2)=0.857,R^(2)=0.862(monthly)and R^(2)=0.227,R^(2)=0.404(annually),respectively;for the whole basin scale was R^(2)=0.902,R^(2)=0.900(monthly)and R^(2)=0.507 and R^(2)=0.519(annually),respectively.The model performed acceptably,and SDC performed the best,indicating that remote sensing data can be used for SWAT model calibration.During 2009-2018,ET generally increased in the Madu River Basin(SDC results,7.21 mm/yr),with a multiyear average value of 734.37 mm/yr.The annual ET change rate for the sub-basin was relatively low upstream and downstream.The linear correlation analysis between ET and meteorological factors shows that on the monthly scale,precipitation,solar radiation and daily maximum and minimum temperature were significantly correlated with ET;annually,solar radiation and wind speed had a moderate correlation with ET.The correlation between maximum temperature and ET is best on the monthly scale(Pearson correlation coefficient R=0.945),which may means that the increasing ET originating from increasing temperature(global warming).However,the sub-basins near Shennongjia Nature Reserve that are in upstream have a negative ET change rate,which means that ET decreases in these sub-basins,indicating that the’Evaporation Paradox’exists in these sub-basins.This study explored the potential of remote-sensing-based ET data for hydrological model calibration and provides a decision-making reference for water resource management in the Madu River Basin.

Numerical simulation of downhole temperature distribution in producing oil wells

An improved numerical simulation method is presented to calculate the downhole temperature distribution for multiple pay zones in producing oil wells. Based on hydrodynamics and heat transfer theory, a 2-D temperature field model in cylindrical coordinates is developed. In the model, we considered general heat conduction as well as the heat convection due to fluid flow from porous formation to the borehole. We also take into account the fluid velocity variation in the wellbore due to multiple pay zones. We present coupled boundary conditions at the interfaces between the wellbore and adjacent formation, the wellbore and pay zone, and the pay zone and adjacent formation. Finally, an alternating direction implicit difference method （ADI） is used to solve the temperature model for the downhole temperature distribution. The comparison of modeled temperature curve with actual temperature log indicates that simulation result is in general quite similar to the actual temperature log. We found that the total production rate, production time, porosity, thickness of pay zones, and geothermal gradient, all have effects on the downhole temperature distribution.

Towards an AI-friendly cross-timescale simulation and analysis platform for electric distribution systems

Substantial changes are occurring in electric distribution systems due to ambitious targets towards carbonneutrality in many regions around the world.One of the key challenges is how to analyze the interactions of massive amount of energy endusers with the electric distribution grid operator.In this paper,we introduce a comprehensive simulation platform,AI4Dist,that is capable to perform a wide collection of distribution system studies that capture multiple timescales ranging from market planning to transient event analysis.AI4Dist is designed to effortlessly integrate with offtheshelf machine learning packages and algorithm implementations.We envision that AI4Dist will serve as a platform to empower researchers with different expertise to contribute to the development of low carbon electricity sector.

The numerical simulation and inversion fitting of radon concentration distribution in homogeneous overburden above active fault zones

Based on the convection and diffusion mechanisms of radon migration, in this paper we deduce the two-dimensional differential equation for radon transportation in the overburden above active fault zones with an unlimited extension along the strike. Making use of the finite difference method, the radon concentration distribution in the overburden above active faults is calculated and modeled. The active fault zone parameters, such as the depth and the width of the fault zone, and the value of radon concentration, can be inverted from the measured radon concentration curve. These realize quantitative interpretation for radon concentration anomalies. The inversion results are in good agreement with the actual fault zone parameters.