A case study of replacing steam turbines with LCI-typevariable-speed drives

The problems and experiences associated with the installation, start-up, and operation of 7000 HP 1800 r/min and 3600 HP 6000 r/min synchronous motors using load commutated inverter (LCI) variable-speed controllers are examined. The application of new technology in existing process units can present some unusual and sometimes perplexing challenges. The steep learning curve, and the fact that most projects are time and money driven, all contribute to the hurdles that must be overcome. The described application of LCI variable-speed drives covered all of the factors. Some of the problems and concerns encountered with this project resulted from equipment previously installed, coupled with the dynamics of the electrical, instrumentation, and process systems. When planning the application of variable-speed drives, factors such as electrical system disturbances, impact of harmonics on the existing equipment, training, commissioning, operator acceptance, craft training, and spare parts all need to be taken into consideration     

The terminal tail region of a yeast myosin-V mediates its attachment to vacuole membranes and sites of polarized growth

The Saccharomyces cerevisiae myosin-V, Myo2p, has been implicated in the polarized movement of several organelles and is essential for yeast viability. We have shown previously that Myo2p is required for the movement of a portion of the lysosome (vacuole) into the bud and consequently for proper inheritance of this organelle during cell division. Class V myosins have a globular carboxyl terminal tail domain that is proposed to mediate localization of the myosin, possibly through interaction with organelle-specific receptors. Here we describe a myo2 allele whose phenotypes support this hypothesis. vac15-1/myo2-2 has a single mutation in this globular tail domain, causing defects in vacuole movement and inheritance. Although a portion of wild-type Myo2p fractionates with the vacuole, the myo2-2 gene product does not. In addition, the mutant protein does not concentrate at sites of active growth, the predominant location of wild-type Myo2p. Although deletion of the tail domain is lethal, the myo2-2 gene product retains the essential functions of Myo2p. Moreover, myo2-2 does not cause the growth defects and lethal genetic interactions seen in myo2-66, a mutant defective in the actin-binding domain. These observations suggest that the myo2-2 mutation specifically disrupts interactions with selected myosin receptors, namely those on the vacuole membrane and those at sites of polarized growth.     

Three-cycle breaker applications

This paper discusses with the medium-voltage (mv), metal-clad switchgear breakers that resulted in many benefits for customers' plant processes. Breaker interrupting time is decreasing, with positive impacts co safety, arc-flash considerations, power cable sizing, construction cost reductions, relay coordination margins, power quality, plus other benefits. This article discusses these benefits in detail with supporting mathematical calculations.     

Standards for Grid Computing: Global Grid Forum

Formed in 1999, Global Grid Forum (GGF) is an international organization focused on the development of common practices, agreements, and specifications that will promote interoperability and reuse of Grid technologies. To this end, GGF supports a recommendations process modeled after the Internet Standards Process and carried out through working groups. To ensure that the recommendations process operates with understanding about both research directions and end user requirements, GGF also operates a set of research groups. Finally, GGF supports a set of educational and informational activities designed to support and expand the community of Grid developers, researchers, practitioners and end-users.     

Risk status for dropping out of developmental followup for very low birth weight infants

Not keeping scheduled visits for medical care is a major health care issue. Little research has addressed how the interaction of demographic and biomedical parameters with psychosocial processes has an impact on appointment keeping. Typical factors are stress of daily living, methods of coping, social support, and instrumental support (that is, tangible assistance). In this study, the authors examine the role of these parameters and processes in the risk status for dropping out of a developmental followup program for very low birth weight infants. The findings suggest that the stress of daily living is a significant predictor for the mother's return when the infant is 6 months of age (corrected for prematurity). The predictors for return at 24 months corrected age include marital status, race, gestational age of the infant, maternal intelligence, and efficacy expectations. Providing transportation was found to be a successful intervention strategy for a subgroup at very high risk for dropping out due to a constellation of biomedical, demographic, and psychosocial factors.     

Structure and mechanical properties of Al/AlxOy vacuum- deposited laminates

High yield strength materials can be fabricated by many techniques. A method proposed by Koehler is to alternate thin layers of a high shear modulus material with thin layers of a low shear modulus material. The layers must be less than one hundred atomic layers in thickness and must be single crystals of similar lattice spacing epitaxially grown on top of each other. The mechanical effect is to inhibit dislocation formation and the mobility of dislocations through the solid. The stress required to move a dislocation through the laminate can be of the order of 1% of the lower modulus material.A novel technique has been developed to produce a laminate of Al/Al_xO_y by a pulsed gas process in an electron beam gun system. Samples of 25 μm and thicker have been readily produced. The surface finish of the growing deposit appears to remain as smooth as the glass substrate. The tensile testing data for layer spacings of 50–1200 nm show that the material obeys a Hall-Petch relation for yield strength. The friction stress was measured directly on a pure vapor-deposited sample at 27 MPa. The K value was found to be 0.086 MN m^{-$\text{3}\text{2}$}.     

Supercomputing-balancing resources

The need for high-speed data communications and mass storage systems for supercomputing is examined. The former could be serious bottlenecks in the not-too-distant future, because their capabilities have not kept up with those of supercomputers themselves. The potential of fiber-optic technologies for meeting data communication requirements is discussed, and research around the world is briefly cited. Trends in mass storage are briefly discussed     

In search of gigabit applications

Applications in existing specialized, metacomputer environments and those yet to be developed for services such as telecommunications, distributed data, and image transfer that will require networks which can handle volumes of data on the order of gigabits per second are discussed. Specific examples are presented from the fields of computational science, data navigation, and collaborative environments and instrument control. It is concluded that distributed computing and collaborative environments that support the interaction of multiple computers, as well as the interaction of computers with humans, are the paradigms that will characterize gigabit applications