Years Of Operating Experience Research Articles

Model Output Statistics Forecasts: Three Years of Operational Experience in the Netherlands

Abstract In the Netherlands, one to five day Model Output Statistics (MOS) forecasts have been used operationally since November 1983. The weather elements predicted are the probability of precipitation, the conditional probability of frozen precipitation, the probability of thunderstorms, the sunshine, maximum and minimum temperature and the maximum wind speed. For the development of the guidance system, two year of ECMWF data (December 1980–November 1982) were used, while a third year was available as a test period. The period December 1983–November 1986 has been used for verification. Operational forecasters have used the MOS forecast for the preparation of their final forecasts. The results of the MOS forecasts and of subjective forecasts are presented and intercompared in this paper. From this comparison it appears that the forecasters have higher skill scores only for Days 1 and 2; for Days 3, 4 and 5 the differences are, in general, small.

In-Service Availability of the AEP System Control Center

The development period availability expectations for the AEP System Control Center (SCC) are contrasted with the first two years of operational experience. The reasons for in-service unavailability are presented and discussed. Recommendations are made relative to the inclusion of new factors into procurement phase availability calculations and acceptance tests.

In Service Availability of the AEP System Control Center

The development period availability expectations for the AEP System Control Center (SCC) are contrasted with the first two years of operational experience. The reasons for in-service unavailability are presented and discussed. Recommendations are made relative to the inclusion of new factors into procurement phase availability calculations and acceptance tests.

Operation of Diesel Engines on Residual Fuel Oil

The use of residual fuel oil for diesel generation is now well established for base load operation. The North of Scotland Hydro-Electric Board (NSHEB) has some twenty years of operational experience in supplying electricity in the Scottish Islands employing twenty-three K Major diesel engines in four power stations at Kirkwall, Lerwick, Loch Carnan and Stornoway. The paper describes the continuous development work undertaken by the engine manufacturers, Mirrlees Blackstone and the NSHEB, in increasing engine output and efficiency over the period, together with improvements in reliability and durability showing trends in modern engine design leading to the current Mark 3 version of the engine.

Twenty-Five Years of Operating Experience With the Coal-Fired, Closed-Cycle Gas Turbine Cogeneration Plant at Coburg

The only commercially running closed-cycle gas turbine in the world delivering electricity as well as heat to a public utility and a heating network, is the heat and power station in Coburg, West Germany. The plant is fired exclusively with pulverized coal and uses air as the working medium. It has a maximum continuous electric power output of 6.6 MW into the grid and up to 16 MW of direct heating capacity into the town’s heating network. The plant has accumulated 150,000 operating hours to date (approximately 7000 hrs per year); it is scheduled to remain in service during the following years due to its excellent performance. Since relatively little has been published about the plant in the technical literature, a report about its design and operating experience is presented here.

Ten Years of Operating Experience with a Remote Controlled Water Heater Load Management System at Detroit Edison

Detroit Edison has accumulated 10 years' operating experience with a large-scale radio controlled electric water heater Load Management system. The limitations of the actual operating environment, both past and present, have greatly influenced Load Management strategies. Important lessons concerning cost effectiveness have been learned and must be applied to future. undertakings.

Reliable soldering of printed circuit boards : P. J. Bud, 1968 Prod. Ass. Conf. Tech. Exhibition, Long Island, N.Y., June 7–8 (1968), Transactions, p. 333

Life management and structural integrity assessment of bimetallic welds in its state-of-the-art form relies on practical methods derived on the basis of years of experience in operation and simplistic strength of materials analyses. The complex conditions and properties of the weldment, as resulting from the elaborate interaction of different microstructures with gradients in material properties, have limited the ability of currently existing methods to construct the assessment on the basis of actual failure mechanisms of bimetallic welds. Current work addresses the assessment procedure by combining experimental and numerical fracture mechanics comprising a micro-mechanical evaluation of the relevant damage mechanisms. The studied dissimilar ferrite (SA508)–austenite (AISI 304) circumferencial weld is one with a Ni-enriched buttering layer.The experimental work comprises tensile and fracture mechanical characterization of the different microstructural zones of the bimetallic weld. Tensile properties are determined with microstructure specific flat bar specimens as well as round bar specimens enabling better inference of true stress–strain curves. Fracture resistance curves are established by applying small-specimen testing techniques. Different crack configurations are modeled by finite element analysis (FEA) to assess the relationships between fracture types, toughness and local near crack tip constraint parameters. Transferability and characterization question are considered by determining J–Q-trajectories and employing small-scale yielding corrections (SSYCs). On the basis of the experimental and numerical results and a fractographical investigation, the micromechanics of fracture are interpreted. Differences in strain hardening capacities of microstructural zones are found to most severely affect the toughness transitions of the weld and the associated failure modes. Two prime failure types are noted, one for cracks located at outer heat affected zone (HAZ) resulting in an unstable crack deflection towards the fusion line (FL) and another type associated with cracks positioned near the fusion line, wherein a low-toughness ductile fracture process results. Small fracture mechanics specimen is found applicable for fracture resistance determination of bimetallic weldments.

Measuring microbond integrity with an infrared microradiometer : D. H. Schumacher, Mater. Eval., December (1968), p. 257

Life management and structural integrity assessment of bimetallic welds in its state-of-the-art form relies on practical methods derived on the basis of years of experience in operation and simplistic strength of materials analyses. The complex conditions and properties of the weldment, as resulting from the elaborate interaction of different microstructures with gradients in material properties, have limited the ability of currently existing methods to construct the assessment on the basis of actual failure mechanisms of bimetallic welds. Current work addresses the assessment procedure by combining experimental and numerical fracture mechanics comprising a micro-mechanical evaluation of the relevant damage mechanisms. The studied dissimilar ferrite (SA508)–austenite (AISI 304) circumferencial weld is one with a Ni-enriched buttering layer.The experimental work comprises tensile and fracture mechanical characterization of the different microstructural zones of the bimetallic weld. Tensile properties are determined with microstructure specific flat bar specimens as well as round bar specimens enabling better inference of true stress–strain curves. Fracture resistance curves are established by applying small-specimen testing techniques. Different crack configurations are modeled by finite element analysis (FEA) to assess the relationships between fracture types, toughness and local near crack tip constraint parameters. Transferability and characterization question are considered by determining J–Q-trajectories and employing small-scale yielding corrections (SSYCs). On the basis of the experimental and numerical results and a fractographical investigation, the micromechanics of fracture are interpreted. Differences in strain hardening capacities of microstructural zones are found to most severely affect the toughness transitions of the weld and the associated failure modes. Two prime failure types are noted, one for cracks located at outer heat affected zone (HAZ) resulting in an unstable crack deflection towards the fusion line (FL) and another type associated with cracks positioned near the fusion line, wherein a low-toughness ductile fracture process results. Small fracture mechanics specimen is found applicable for fracture resistance determination of bimetallic weldments.

Assuring integrated circuit reliability during production : D. I. Troxel and B. Tiger, 22nd Am. Soc. Quality Control, Ann. Tech. Conf., Philadelphia, May 6–8 (1968), Transactions, p. 347

Life management and structural integrity assessment of bimetallic welds in its state-of-the-art form relies on practical methods derived on the basis of years of experience in operation and simplistic strength of materials analyses. The complex conditions and properties of the weldment, as resulting from the elaborate interaction of different microstructures with gradients in material properties, have limited the ability of currently existing methods to construct the assessment on the basis of actual failure mechanisms of bimetallic welds. Current work addresses the assessment procedure by combining experimental and numerical fracture mechanics comprising a micro-mechanical evaluation of the relevant damage mechanisms. The studied dissimilar ferrite (SA508)–austenite (AISI 304) circumferencial weld is one with a Ni-enriched buttering layer.The experimental work comprises tensile and fracture mechanical characterization of the different microstructural zones of the bimetallic weld. Tensile properties are determined with microstructure specific flat bar specimens as well as round bar specimens enabling better inference of true stress–strain curves. Fracture resistance curves are established by applying small-specimen testing techniques. Different crack configurations are modeled by finite element analysis (FEA) to assess the relationships between fracture types, toughness and local near crack tip constraint parameters. Transferability and characterization question are considered by determining J–Q-trajectories and employing small-scale yielding corrections (SSYCs). On the basis of the experimental and numerical results and a fractographical investigation, the micromechanics of fracture are interpreted. Differences in strain hardening capacities of microstructural zones are found to most severely affect the toughness transitions of the weld and the associated failure modes. Two prime failure types are noted, one for cracks located at outer heat affected zone (HAZ) resulting in an unstable crack deflection towards the fusion line (FL) and another type associated with cracks positioned near the fusion line, wherein a low-toughness ductile fracture process results. Small fracture mechanics specimen is found applicable for fracture resistance determination of bimetallic weldments.

Ultra reliable submerged repeaters : W. J. Archibald, Electron. Equip. News. February (1968), p. 46

Although still expensive, silicon solar cell arrays are becoming increasingly common for some specialised remote area applications. Within Australia solar photovoltaic generators are being used to provide power for microwave radio repeater stations, VHF subscriber radiotelephone systems, UHF small capacity radio systems, as well as many other professional and commercial applications. In all of this plant it is vital to be able to provide reliable low maintenance primary power. A new generation of low power consumption communication equipment has made it possible to completely power broadband radio relay repeaters using only the solar source with power storage being provided by storage batteries of the pure-lead positive pasted-plate type. Several years of operational experience in remote locations have now been obtained with this solar generating equipment.

The First Two Years of Operational Experience with the Sikorsky S-61

In the early 1930s, when the 14-passenger DC-2 made its appearance, it was regarded as too big for anything but transcontinental operations, both from the standpoint of capacity and airport requirements. When its follow-on, the 21-passenger DC-3, came along, it sparked a mammoth new Federal Airport Programme, and several regional air carriers in the United States almost choked on red ink. Others merged into systems big enough to absorb this monster.Had someone suggested that within a short span of three decades a helicopter carrying 28 passengers would be hedge-hopping around Southern California, operating day and night from “micro” airports, which we call heliports, I am afraid he would have been given a silent stare.

Effect of Taper on Screw-Thread Load Distribution

Abstract The load distribution on the threads of bolts and nuts, made in the conventional constant-pitch manner and with tapered threads, was determined experimentally and theoretically. The results indicate that substantial improvement, in the order of 2 to 1, in thread load distribution can be made by tapering the thread of either the bolt or nut properly. Material improvement in bolting strength is obtained in applications that normally are conducive to little plastic flow and thus liable to result in brittle fractures, such as are encountered with dynamic loads or static loads at elevated temperatures. Ten years of operational experience on high-temperature high-pressure turbine bolting is cited to substantiate indicated improvements.