A transputer-based real-time digital transient network analyzer

Experiences on using a workstation cluster to implement a real-time digital transient network analyzer

This paper describes a methodology for estimating the numerical errors in real-time simulation based on comparing two real-time simulations, one with the nominal integration step size and the second with an augmented step size. Accurate interpolation formulas are then used to convert the outputs from the second simulation to outputs at the discrete times for the first simulation. This permits a direct computation of the difference between the two simulations at common discrete times. Assuming that the dynamic errors vary as hk, where h is the integration step size and k is known, a simple formula can then be used to calculate the deviation of either simulation from the solution for zero step size. While only approximate, this procedure results in dynamic error estimates that are surprisingly accurate, as demonstrated in the paper in example simulations that use both single and multi-rate integrations. It turns out that three simulations, each with a different integration step size, can be used to estimate the exponent k in the dependence of dynamic errors on hk. This in turn allows programming errors, such as the inadvertent introduction of a one-frame delay within the simulation code, to be identified. The author feels that the methodology described in the paper can play a major role in optimizing as well as verifying the dynamic fidelity of real-time, hardware-in-the-loop simulations.

A few years ago, the study and simulation of fast power system phenomena in real-time, was the private ground of analog simulators. But the limitation in modeling, the complexity and the costly maintenance of these simulators was a brake upon their development and made their profitability uncertain. The testing of power system equipment such as controls, relays or power electronic devices needed a new type of simulator, much more versatile and cost-efficient than their predecessors: the real-time digital transient network analysers (DTNA). Until a few months ago, the design of DTNAs was based on dedicated technologies. Today, the ever increasing calculation power has now reached a level that allows real-time simulations of fast phenomena to be carried on standard computers. The authors present in this paper a new and fully digital TNA that relies on a standard computer.

Steady-state overvoltages can occur on EHV transmission systems during various system operating conditions. The voltage waveforms are characterized by a periodic waveform which may be distorted by harmonics if iron saturation of equipment on the lines occurs. This paper discusses the results of digital and transient network analyzer (Anacom) studies which analyzed system parameters with respect to their effect on harmonics in steady-state overvoltages. Special emphasis was focused on the factors influencing harmonic distortion of the steady-state voltages.

Tectonic movement along faults is often reflected by characteristic geomorphological features such as linear valleys, ridgelines and slope‐breaks, steep slopes of uniform aspect, regional anisotropy and tilt of terrain. Analysis of digital elevation models, by means of numerical geomorphology, provides a means of recognizing fractures and characterizing the tectonics of an area in a quantitative way. The objective of this study is to investigate the use of numerical geomorphometric methods for tectonic geomorphology through a case study. The methodology is based on general geomorphometry. In this study, the basic geometric attributes (elevation, slope, aspect and curvatures) are complemented with the automatic extraction of ridge and valley lines and surface specific points. Evans' univariate and bivariate methodology of general geomorphometry is extended with texture (spatial) analysis methods, such as trend, autocorrelation, spectral, and network analysis. Terrain modelling is implemented with the integrated use of: (1) numerical differential geometry; (2) digital drainage network analysis; (3) digital image processing; and (4) statistical and geostatistical analysis. Application of digital drainage network analysis is emphasized. A simple shear model with principal displacement zone with an NE–SW orientation can account for most of the the morphotectonic features found in the basin by geological and digital tectonic geomorphology analyses. Copyright © 2003 John Wiley & Sons, Ltd.

This paper considers software tools and linguistic constructions of the network simulator TRIADNS. Nowadays network applications - especially in the area of wireless networks - are becoming more and more complex which makes the design and the testing almost impossible without appropriate software. This software available to aid the user in simulating previously designed scenarios, scalable algorithms and changing structure of computer network. So it is necessary to have effective and flexible program tools for computer network design and simulation. Network simulator must design and investigate not only hardware, but software too, explore computer networks, considering in particular the specific characteristics of a variety of computer networks. Besides computer networks may include a lot of nodes. This paper discusses approaches allowing to decide the problems mentioned above: hierarchical model, using ontologies and Data Mining methods for the analyses of simulation results, using several computing nodes for computer network simulation (distributed and parallel simulation).

The software and digital is the development trend of vector network analysis. Combined with the idea of software radio, this paper presented a design scheme of vector network analyzer and discussed the key technologies and implementation. Firstly this paper studied the principle and composition of vector network analyzer, the overall design of the system hardware was given. Secondly, we discussed the related theories of the design and key technology. The research contents include: The technology of real-time wideband spectrum analysis, Real time dynamic range expanding technology, Wideband digital downconversion Technology, and Variable rate signal processing. The system structure and working process of the key system function had detailedly designed. Through the numerical simulation and experimental verification, we proved the correctness and feasibility of the design scheme.

Simulation of computer networks is an area of growing interest. Network simulation is a multidisciplinary endeavor requiring expertise in computer networking, modeling and simulation, and software engineering. Network modeling and simulation tools in the research community provide important exemplar technology that has the potential for reuse. NetSim, developed at the Massachusetts Institute of Technology, is an excellent example of a network simulation infrastructure that can support a variety of modifications. In this paper we discuss NetSim and two additional tools: the Maryland Routing Simulator and the Texas A&M Asynchronous Transfer Mode Simulator, which are both modifications of NetSim. NetSim can serve as a simple but effective Ethernet or point-to-point network simulator. Additionally, NetSim can serve as a rapid prototyping tool for other network simulators.

A project titled “Establishing the advanced disaster reduction management system by fusion of real-time disaster simulation and big data assimilation,” was launched as Core Research for Evolutional Science and Technology (CREST) by the Japan Science and Technology Agency (JST). Intended to save as many lives as possible in future national crises involving earthquake and tsunami disasters, the project works on a disaster mitigation system of the big data era, based on cooperation of large-scale, high-resolution, real-time numerical simulations and assimilation of real-time observation data. The world’s most advanced specialists in disaster simulation, disaster management, mathematical science, and information science work together to create the world’s first analysis platform for real-time simulation and big data that effectively processes, analyzes, and assimilates data obtained through various observations. Based on quantitative data, the platform designs proactive measures and supports disaster operations immediately after disaster occurrence. The project was launched in 2014 and is working on the following issues at present.Sophistication and fusion of simulations and damage prediction models using observational big data: Development of a real-time simulation core system that predicts the time evolution of disaster effect by assimilating of location information, fire information, and building collapse information which are obtained from mobile terminals, satellite images, aerial images, and other new observation data in addition to sensing data obtained by the undersea high-density seismic observation network.Latent structure analysis and major disaster scenario creation based on a huge amount of simulation results: Development of an analysis and extraction method for the latent structure of a huge amount of disaster scenarios generated by simulation, and creation of severe scenarios with minimum “unexpectedness” by controlling disaster scenario explosion (an explosive increase in the number of predicted scenarios).Establishment of an earthquake and tsunami disaster mitigation big data analysis platform: Development of an earthquake and tsunami disaster mitigation big data analysis platform that realizes analyses of a huge number of disaster scenarios and increases in speed of data assimilation, and clarifies the requirements for operation of the platform as a disaster mitigation system.The project was launched in 2014 as a 5-year project. It consists of element technology development and system fusion, feasibility study as a next-generation disaster mitigation system (validation with/without introduction of the developed real-time simulation and big data analysis platform) in the affected areas of the Great East Japan Earthquake, and test operations in affected areas of the Tokyo metropolitan earthquake and the Nankai Trough earthquake.

Real-time power system simulator testing has proven to be an invaluable means to evaluate relay performance under realistic conditions. This paper exposes the configuration and the performance of a real time digital transient network analyser (DTNA) in closed loop testing of a distance protection system in a series compensated network. A power system simulator for relay testing should be flexible in configuration and parameter adjustment and it should provide for a rapid execution of test cases. It must not only function in real time, but in a closed-loop mode with relays tripping circuit breakers within the simulator. This paper describes the ARENE DTNA.

With the development of the space industry, LEO simulation platforms are increasingly important. Prior work mainly focused on the dynamics of constellation topology, routing algorithms against the topological motion, and the behavior of LEO constellation networks, but neglected real-time and completeness properties. In our work, we design a real-time and complete network simulation framework, named LEOCN, that is more meaningful and detailed for researchers than previous work on LEO satellite constellation simulations. LEOCN is supported by Linux System, which makes the framework more realistic and relieves the computational burden. Meanwhile, LEOCN deeply considers topology and routing algorithms, visualization, satellite mobility, communication protocols, and network traffic problems. On LEOCN, we can deploy routing algorithm experiments via SDN. We evaluate the performance of LEOCN in large-scale constellation scenarios, and the results demonstrate the superiority of the real-time and complete network simulation framework.

In this work, polyaniline co-doped with (IS)-(+)-10-camphorsulfonic acid (D-CSA) and Ni2+ was synthesized via in situ polymerization. The structure, conductivity and electromagnetic parameters of the resulting polyaniline were characterized by FTIR, SZ82 digital multimeter and AV3618 network analyzer. The conductivity of polyaniline at room temperature increases with increasing of Ni2+ loading. Moreover, the resulting polyaniline co-doped with Ni2+ displays obvious magnetic loss at the microwave frequency. So, we suppose that this conducting polymer can be used as microwave absorbing material with wide-range and good effect.

This case study profiles the steps taken to develop a process for developing a transportation information management system protype. The case study was initiated in response to a pattern of growth whereas, Tanzania is increasingly becoming a mobile society that suffers severely from traffic congestion, delay and mobile source pollution. Meeting the challenges of greater mobility, accessibility, land use development, economic growth and revenue constraints requires that transport investment and maintenance strategies be optimized. In this case study we define transportation information management system (TIMS), in the context of the Tanzania 2014 transportation network. In doing so an argument is made for developing a base line digital transport network analysis, as a starting point. In doing so, we identify a suite of decision-making tools and a stable of performance variables. As well, this case study presents a draft: work plan which emerged during this effort. Developing effective congestion relief strategies requires going beyond the collection of geotechnical like shoulder width, guardrails, vegetation, road length and width, culverts, volume, drainage, terrain, rail crossing, number of lanes, bridges locations, and type of terrain. A comprehensive analysis of congestion requires a fully loaded transportation database with the following characteristics: regional, trunk line, and local roads; travel, time, ADT, population, employment, landuse, and income data at the regional and ward level and; transit line and multi modal infrastructure data. To test multiple congestion mitigation strategies advanced analysis tools are helpful to analyze the impact that network connectivity, pedestrian flows, population growth, travel demand, landuse, and community have accessibility. Equally important is the need have a skilled professional, and technical workforce that has not only the theoretical knowledge but also the technical training to use buffer, proximity, travel demand and simulation tools to assess the impacts of population concentrations, vehicle travel and goods movement.

This article begins by introducing Jonathan Edwards, the eighteenth century American philosopher theologian from Northampton, Massachusetts. Edwards believed that the world of nature had communicative properties, full of types and symbols, and indeed, was a kind of language of God. This article posits that Edwards’ typological language of nature, encapsulated in his notebook “Images of Divine Things” and throughout his written corpus, can be explored through the lense of Digital Humanities and network analysis using Processing and Python programming languages. Next, the article summarizes recent Edwards-focused DH projects by Kenneth Minkema, Michał Choiński, and Michael Keller. The article then recounts the history and development of the Visual Edwards project and how it expands exploration of the 26 volume Yale letterpress edition of The Works of Jonathan Edwards. Features of the Visual Edwards software are introduced briefly, as well as print publications flowing from the project.

This paper presents the features of the implementation of automatic exciting regulators (AER) models in the Hybrid Real-Time Power System Simulator (HRTSim). This simulator has unique abilities: simulation without decomposition, no restrictions on the dimension of the simulated power system, realtime simulation, exclusion of methodological error of simulation, usage of full and adequate models of primary and auxiliary power system equipment. These features allow using HRTSim for a variety of tasks in the energy sector. The article presents fragments of AER research and setting in Tomsk power system with using of HRTSim.