Geographically distributed real-time digital simulations using linear prediction

Real-time (RT) simulator is a powerful tool for analyzing operational and control algorithms in electric power systems engineering. For understanding the dynamic and transient behavior of a power systems, significant RT computation capabilities are essential. A single unit of RT simulator has limited simulation capabilities. The most common way of augmenting simulation capability is using a bank of locally connected RT simulators. However, creating a large-sized bank of RT simulators involves significant financial investments and hence may not be feasible at all research facilities. Power and energy systems research facilities that use RT simulators are at diverse physical locations. In addition to RT simulators, research facilities around the world house an array of facilities with unique power, energy, and control systems for innovative research. To leverage these unique research facilities, geographically distributed RT simulation based on Wide Area Network (WAN) is required. Typical RT simulators perform simulations with time-steps in the order of milliseconds to microseconds, whereas data latency for communication on WAN may be as high as a few hundred milliseconds. Such communication latency between RT simulators may lead to inaccuracies and instabilities in geographically distributed RT simulations. In this paper, the effect of communication latency on geographically distributed RT simulation is discussed and analyzed. In order to reduce the effect of the communication latency, a Real-Time Predictor (RTP), based on linear curve fitting is developed and integrated into the distributed RT simulation environment. Two geographically distributed digital RT simulators are used to perform dynamic simulations of an electric power system with a fixed communication latency and the predictor. Empirical results demonstrate the effects of communication latency on the simulation and the performance of the RTP to improve the accuracy of simulations.     

Human error probability estimation by coupling simulator data and deterministic analysis

Operator error in diagnosis and execution of task have significant impact on Nuclear Power Plant (NPP) safety. These human errors are classified as mistakes (rule base and knowledge based errors), slip (skill based) and lapses (skill based). Depending on the time of occurrence, human errors have been categorized as i) Category ‘A’ (Pre-Initiators): actions during routine maintenance and testing wherein errors can cause equipment malfunction ii) Category ‘B’ (Initiators): actions contributing to initiating events or plant transients iii) Category ‘C’ (Post-Initiators): actions involved in operator response to an accident. There have been accidents in NPPs because of human error in an operator's diagnosis and execution of an event. These underline the need to appropriately estimate HEP in risk analysis. There are several methods that are being practiced in Probabilistic Safety Assessment (PSA) studies for quantification of human error probability. However, there is no consensus on a single method that should be used. In this paper a method for estimating HEP is proposed which is based on simulator data for a particular accident scenario. For accident scenarios, the data from real NPP control room is very sparsely available. In the absence of real data, simulator based data can be used. Simulator data is expected to provide a glimpse of probable human behavior in real accident situation even though simulator data is not a substitute for real data. The proposed methodology considers the variation in crew performance time in simulator exercise and in available time from deterministic analysis, and couples them through their respective probability distributions to obtain HEP. The emphasis is on suitability of the methodology rather than particulars of the cited example.     

SDMSim: A manufacturing service supply–demand matching simulator under cloud environment

Nowadays, with the introduction and application of new information technologies in manufacturing, various advanced manufacturing modes and national strategies have been put forward and paid more and more attention, such as Industry 4.0, Industrial Internet, Cyber-Physical System or Cyber Manufacturing, Made in China 2025, Internet Plus Manufacturing, Cloud Manufacturing, etc. For these modes and strategies, how to realize the effective and intelligent supply–demand matching (SDM) of various manufacturing resources and capabilities (MR&C) in the form of service is one of the common issues and aims. In order to provide a uniformed research platform for related researchers both in academic and industry, the concept of manufacturing service SDM simulator (SDMSim) is proposed in this paper. A hypernetwork based architecture for the simulator is designed, as well as its seven key functions and subsystems, including manufacturing service management, manufacturing task management, manufacturing service SDM hypernetwork, manufacturing service SDM problem formulation and configuration, matching and scheduling algorithms/strategies selection and design, statistical analysis, and visualization. It illustrates that SDMSim has the potential to serve the users of manufacturing service provider, manufacturing service consumer, manufacturing service operator in the field of SoM, as well as the related researchers.     

The sensitivity of laboratory tests assessing driving related skills to dose-related impairment of alcohol: A literature review

Laboratory tests assessing driving related skills can be useful as initial screening tools to assess potential drug induced impairment as part of a standardized behavioural assessment. Unfortunately, consensus about which laboratory tests should be included to reliably assess drug induced impairment has not yet been reached. The aim of the present review was to evaluate the sensitivity of laboratory tests to the dose dependent effects of alcohol, as a benchmark, on performance parameters. In total, 179 experimental studies were included. Results show that a cued go/no-go task and a divided attention test with primary tracking and secondary visual search were consistently sensitive to the impairing effects at medium and high blood alcohol concentrations. Driving performance assessed in a simulator was less sensitive to the effects of alcohol as compared to naturalistic, on-the-road driving. In conclusion, replicating results of several potentially useful tests and their predictive validity of actual driving impairment should deserve further research. In addition, driving simulators should be validated and compared head to head to naturalistic driving in order to increase construct validity.     

Active-reactive scheduling of activedistribution system considering interactiveload and battery storage

The increasing penetration of inverter-based distributed generations (DGs) significantly affects the fault characteristics of distribution networks. Fault analysis is a keystone for suitable protection scheme design. This paper presents the modelling methodology for distribution networks with inverter-based DGs and performs fault simulation based on the model. Firstly, a single inverter-based DG model based on the cascaded control structure is developed. Secondly, a simulation model of distribution network with two inverter-based DGs is established. Then, different fault simulations are performed based on the Real Time Digital Simulator (RTDS). Theoretical analyses are conducted to justify the simulation results, including the equivalent circuit of distribution networks with inverter-based DGs and the solution method for loop currents     

Methane steam reforming for synthetic diesel fuel production from steam-hydrogasifier product gases

Steam-methane reforming (SMR) reaction was studied using a tubular reactor packed with NiO/γ-Al₂O₃ catalyst to obtain synthesis gases with H₂/CO ratios optimal for the production of synthetic diesel fuel from steam-hydrogasification of carbonaceous materials. Pure CH₄ and CH₄-CO₂ mixtures were used as reactants in the presence of steam. SMR runs were conducted at various operation parameters. Increasing temperature from 873 to 1,023 K decreased H₂/CO ratio from 20 to 12. H₂/CO ratio decreased from 16 to 12 with pressure decreasing from 12.8 to 1.7 bars. H₂/CO ratio also decreased from about 11 to 7 with steam/CH₄ ratio of feed decreasing from 5 to 2, the lowest limit to avoid severe coking. With pure CH₄ as the feed, H₂/CO ratio of synthesis gas could not be lowered to the optimal range of 4–5 by adjusting the operation parameters; however, the limitation in optimizing the H₂/CO ratio for synthetic diesel fuel production could be removed by introducing CO₂ to CH₄ feed to make CH₄-CO₂ mixtures. This effect can be primarily attributed to the contributions by CO₂ reforming of CH₄ as well as reverse water-gas shift reaction, which led to lower H₂/CO ratio for the synthesis gas. A simulation technique, ASPEN Plus, was applied to verify the consistency between experimental data and simulation results. The model satisfactorily simulated changes of H₂/CO ratio versus the operation parameters as well as the effect of CO₂ addition to CH₄ feed.     

高性能网络处理器同时多线程结构设计与研究

网络带宽的快速增长使得网络的瓶颈由带宽逐渐变成了节点设备。网络处理器则通过良好的体系结构设计和专门针对网络处理优化的部件，为上层提供了一个良好的可编程环境。系统级模拟是在制造芯片前设计现代网络处理器的有效方法。本文基于专用的网络处理器测试基准和处理器模拟器设计了适合于网络处理的同时多线程结构，它结合了指令级并行和线程级并行的优点，经过测试获得了高性能。同时分析了线程个数对系统性能和处理器面积的影响，并根据综合评价函数选择了优化的线程数为6。     

面向对象的实时三维视景仿真系统的实现

视景仿真是计算机仿真研究的一个重点。复杂三维场景的管理是视景仿真中所必须解决的问题。文章提出了一种面向对象的三维场景模型的数据结构,讨论了基于这种数据结构的实时视景仿真系统的实现。     

潜艇航行训练模拟器视景仿真中的三维场景显示

该文主要论述了在潜艇航行训练模拟器三维视景仿真中，把三维模型投影到屏幕坐标系当中的方法。该方法是利用Direct3D的几何管道，使模型中顶点依次经过世界变换、视变换、投影变换和屏蔽载减最后输出到光栅上。     

航海雷达电磁波绕射仿真模型及其应用

模拟电磁波浇射并应用于航海雷达模拟器，突破了雷达模拟技术中多年一成不变的几何关系运算。实践证明，这种模拟方法能够大幅度提高航海雷达仿真质量。