Microwave integrated circuits for space applications

Monolithic microwave integrated circuits (MMIC), which incorporate all the elements of a microwave circuit on a single semiconductor substrate, offer the potential for drastic reductions in circuit weight and volume and increased reliability, all of which make many new concepts in electronic circuitry for space applications feasible, including phased array antennas. NASA has undertaken an extensive program aimed at development of MMICs for space applications. The first such circuits targeted for development were an extension of work in hybrid (discrete component) technology in support of the Advanced Communication Technology Satellite (ACTS). It focused on power amplifiers, receivers, and switches at ACTS frequencies. More recent work, however, focused on frequencies appropriate for other NASA programs and emphasizes advanced materials in an effort to enhance efficiency, power handling capability, and frequency of operation or noise figure to meet the requirements of space systems

Geoarchaeological Modeling of Late Paleoindian Site Location in the Northwestern Great Lakes Region

Full-time occupation of recently deglaciated landscapes in the northwestern Great Lakes by late Paleoindian groups marks a key milestone in the colonization of the region, yet settlement-subsistence systems of these colonizing populations remains poorly understood. Here we apply geoarchaeological modeling and early Holocene environmental reconstruction to analyze environmental settings of known late Paleoindian sites in Michigan’s Upper Peninsula. Our results reveal significant settlement patterning associated with this early Holocene record, highlighting the spatial correlation between site locations and high ground adjacent to hilly terrain and inland lakes – prime locations for monitoring the movement of large game. The analysis highlights a core area with a high likelihood for undiscovered late Paleoindian sites in the northwest corner of Marquette County and suggests the possibility of a north-south travel corridor into the region from upper Wisconsin along the Michigamme River

The Replication of Bacteriophage MS2: IX. Structure and Replication of the Replicative Intermediate

Experiments are described to determine whether the ribonuclease-sensitive component of the replicative intermediate formed during RNA bacteriophage infection is the nascent strand (conservative replication), or is a displaced portion of the viral strand of the RNA duplex (semi-conservative replication). Appropriate labeling experiments indicate that this component arises in each replicative intermediate molecule, with equal probability, from either origin. Those replicative intermediate molecules in which the nascent strand is ribonuclease-sensitive are more readily denatured than those in which the viral strand is partially displaced. The two types of replicative intermediate can be distinguished on this basis. It is proposed that each replicative intermediate molecule replicates both conservatively and semi-conservatively, equally often

Light detection and ranging (LiDAR) and multispectral studies of disturbed Lake Superior coastal environments

Due to its high spatial resolution and excellent water penetration, coastal light detection and ranging (LiDAR) coupled with multispectral imaging (MSS) has great promise for resolving shoreline features in the Great Lakes. Previous investigations in Lake Superior documented a metal-rich “halo” around the Keweenaw Peninsula, related to past copper mining practices. Grand Traverse Bay on the Keweenaw Peninsula provides an excellent Great Lakes example of global mine discharges into coastal environments. For more than a century, waste rock migrating from shoreline tailings piles has moved along extensive stretches of coast, damming stream outlets, intercepting wetlands and recreational beaches, suppressing benthic invertebrate communities, and threatening critical fish breeding grounds. In the bay, the magnitude of the discarded wastes literally “reset the shoreline” and provided an intriguing field experiment in coastal erosion and spreading environmental effects. Employing a combination of historic aerial photography and LiDAR, we estimate the time course and mass of tailings eroded into the bay and the amount of copper that contributed to the metal-rich halo. We also quantify underwater tailings spread across benthic substrates by using MSS imagery on spectral reflectance differences between tailings and natural sediment types, plus a depth-correction algorithm (Lyzenga Method). We show that the coastal detail from LiDAR and MSS opens up numerous applications for ecological, ecosystem, and geological investigations

Thrust Balance Line Bolts Failure

Case Stud

Smart grid futures: Perspectives on the integration of energy and ICT services

The entire electricity infrastructure and associated socio-technical system including transmission and distribution networks, the system operator, suppliers, generators, consumers and market mechanisms will need to evolve to realize the full potential of smart-grids. At the heart of this evolution is the integration of information and communication technology (ICT) and energy infrastructures for increasingly decentralized development, monitoring and management of a resilient grid. This paper identifies the challenges of integration and four key areas of future research and development at the intersection of energy and ICT: standards-based interoperability, reliability and security, decentralized and self-organizing grid architecture, and innovative business models to unlock the potential of the energy value chain. The ideas postulated here are envisaged to act as a starting-point for future R&D direction