A new digital algorithm for adaptive reclosure of transmission lines

Contents A new numerical algorithm for blocking autoreclosure during permanent faults on overhead lines is presented. The fault nature (permanent or transient) is determined from the voltage signal of faulted and tripped line phase using Least Error Squares Technique. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of presented algorithm to determine the secondary arc extinction time.

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übersicht Es wird ein neuer Algorithmus für das Blockieren des selbst?tigen Wiederzuschaltens bei Dauerfehlern auf Freileitungen vorgestellt. Die Art des Fehlers (dauernd oder transient) wird aus dem Spannungssignal der fehlerbehafteten und unterbrochenen Leitungsphase mittels einer Technik der kleinsten Fehlerquadrate ermittelt. Mit aufgezeichneten Signalen von einem realen Energieversorgungssytem wurde der Algorithmus erfolgreich getestet. Die Ergebnisse verdeutlichen die F?higkeit des vorgestellten Verfahrens, die L?schzeit des sekund?ren Lichtbogens zu ermitteln.

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Received: 22 June 1999     

Synthesis of high surface area ZnO powder by continuous precipitation

Synthesis of high surface area ZnO powder was achieved by continuous precipitation using zinc ions and urea at low temperature of 90 °C. The powder precipitated resulted in high-purity single-phase ZnO powder when calcined at 280 °C for 3 h in air. The solution pH and the precipitation duration strongly affected the surface area of the calcined ZnO powder. Detailed structural characterizations demonstrated that the synthesized ZnO powder were single crystalline with wurtzite hexagonal phase. The powdered samples precipitated by homogeneous precipitation crystallized directly to hydrozincite without any intermediate phase formation.The phase structures, morphologies and properties of the final ZnO powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering particle size analysis (DLS), and nitrogen physisorption in order to determine the specific surface area (BET) and the pore size distribution (BJH).     

The analysis of process variables influencing some characteristics of permeate from ultra- and nanofiltration in sugar beet processing

The aim of this paper is to analyze effect of operating conditions (duration, flow rate, temperature and transmembrane pressure) on the purity ratio, colour changes and turbidity changes of the permeates obtained by ultrafiltration (UF) and nanofiltration (NF) applied for the clarification and purification of sugar syrup solution. The analysis was based on the results of experiments performed in batch conditions, with 2 L of the initial syrup., on two types of the flat, cross-flow membranes: polyethersulfone for the UF process, and polyamide for the NF process. The plan of the experiments was in accordance with a full factorial design, and the 12-parameter polynomial proved adequate for data processing in all the examined cases. It was found that the response surfaces do not have extremes. However, the conclusions towards optimization of operating conditions, in most cases, were as follows: (1) process duration could be shortened, (2) flow rate should be kept at the lower boundary and (3) transmembrane pressure should be kept at the upper boundary of the investigated experimental space. Temperatures in the previous stages of the process mostly determined temperature at separation. The higher the temperature at separation, the lower the effect of separation.     

Sulphidation of Low-Alloyed Steels Used in Power Industry

Oxidation of Metals - This paper reports the results obtained from sulphidation tests on a low-alloyed steels 15HM (T/P12), 16M (T/P1), 18K and 10HM2 (T/P22) in the temperature range...     

DyProSD: a dynamic protocol specific defense for high-rate DDoS flooding attacks

Microsystem Technologies - High-rate distributed denial of service (HDDoS) flooding attacks pose as a major threat to the Internet. Most present solutions based on machine learning approach are...     

Separation of non-sucrose compounds from syrup as a part of the sugar-beet production process by ultrafiltration with ceramic membranes

Non-sucrose compounds having intensive colour tend to build into the sucrose crystals during the crystallization. Their removal, or decrease of their concentration in sugar syrup, is a very important operation. The subject of this laboratory investigation was a separation process performed by ceramic tubular membrane in two modes of operation: with static mixer (SM) and without static mixer (NSM). In order to compare two alternatives as well as to determine optimal operating conditions, in both modes, solution flow rate, temperature, transmembrane pressure and process duration were varied independently and their influence on the permeate flux as well as on the efficiency of decolourization and purification were examined. The cross-flow filtration was carried out on ceramic tubular membrane with pore diameter of 20 nm. The obtained results have shown that permeate flux increased approximately 30%, at 80 °C, and 65%, at 70 °C, when static mixer was used. Significant part of coloured compounds—45% in average, determined by the absorbance measurement of permeate/feed, was separated from the raw sugar syrup. Decolourization in SM-mode is greater than the decolourization in NSM-mode (30% after 0.5 h and 55% after 2 h). Purity was eliminated with an efficiency of 80% in average compared to the feed, with the similar success when NSM-mode and SM-mode of operation were applied, particularly at the end of ultrafiltration.     

Target tracking by fusion of random measures

In this paper we propose fusion methods for tracking a single target in a sensor network. The sensors use sequential Monte Carlo (SMC) techniques to process the received measurements and obtain random measures of the unknown states. We apply standard particle filtering (SPF) and cost-reference particle filtering (CRPF) methods. For both types of filtering, the random measures contain particles drawn from the state space. Associated to the particles, the SPF has weights representing probability masses, while the CRPF has user-defined costs measuring the quality of the particles. Summaries of the random measures are sent to the fusion center which combines them into a global summary. Similarly, the fusion center may send a global summary to the individual sensors that use it for improved tracking. Through extensive simulations and comparisons with other methods, we study the performance of the proposed algorithms. This work has been supported by the National Science Foundation under Award CCF-0515246 and the Office of Naval Research under Award N00014-06-1-0012.