Performance of a 5-MW(e) binary geothermal-electric power plant

A 5-MW(e) Pilot Geothermal Power Plant was built by the Idaho National Engineering Laboratory (INEL), at Raft River, Idaho, as an integral part of the Department of Energy's plan for commercial development of geothermal energy. The purpose of the plant was to investigate the technical feasibility of utilizing a moderate temperature hydrothermal resource (275 to 300/sup 0/F) to generate electrical power in an environmentally acceptable manner. The plant used a dual-boiling binary cycle with isobutane as the working fluid, and drew thermal energy from a 280/sup 0/F liquid-dominated resource. This paper presents the results of that testing, and compares both component and system performance to the performance predicted prior to operation

Realistic Operational Modeling for a Spin Stabilized CubeSat: Challenges and Anticipated Control Performance

Recently, ASTRA LLC. has teamed with the Space Dynamics Laboratory of Utah State University to design a 1.5U CubeSat system for measuring electric fields. Such a system requires 2-axis control and relatively high spin-rates. The spacecraft is called the Double-probe Instrumentation for Measuring Electric-fields (DIME) SensorSat and is funded by the Air Force Research Laboratory SBIR program. In order to design and test control algorithms and verify requirements, ASTRA has developed a modeling-tool for a CubeSat 2-axis control system. First, a brief overview of the DIME SensorSat and attitude system is provided and the DIME attitude requirements are introduced. Next the operational attitude model is discussed followed by simulation results for the various operational phases of a spin-stabilized CubeSat. Finally, we present some anticipated challenges and related simulations for a spin-stabilized CubeSat

The Type Ia Supernova Rate in Radio and Infrared Galaxies from the CFHT Supernova Legacy Survey

We have combined the large SN Ia database of the Canada-France-Hawaii Telescope Supernova Legacy Survey and catalogs of galaxies with photometric redshifts, VLA 1.4 GHz radio sources, and Spitzer infrared sources. We present eight SNe Ia in early-type host galaxies which have counterparts in the radio and infrared source catalogs. We find the SN Ia rate in subsets of radio and infrared early-type galaxies is ~1-5 times the rate in all early-type galaxies, and that any enhancement is always <~ 2 sigma. Rates in these subsets are consistent with predictions of the two component "A+B" SN Ia rate model. Since infrared properties of radio SN Ia hosts indicate dust obscured star formation, we incorporate infrared star formation rates into the "A+B" model. We also show the properties of SNe Ia in radio and infrared galaxies suggest the hosts contain dust and support a continuum of delay time distributions for SNe Ia, although other delay time distributions cannot be ruled out based on our data.Comment: 14 pages, 6 figures, 7 tables, accepted for publication in A

A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks

This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST), Pakistan, and the Higher Education Commission, Pakistan

Will 2000-Era Retirees Experience the Worst Retirement Outcomes in U.S. History? A Progress Report after 10 Years

We find evidence that retirees in 2000, in particular, are on course to potentially experience the worst retirement outcomes of any retiree since 1926. This holds for a wide variety of asset allocations and withdrawal rate strategies. Wealth depletion is taking place more rapidly for 2000-era retirees than for retirees who even endured the Great Depression or the stagflation of the 1970s. Though moderate inflation during the past decade has resulted in current withdrawal rates that are a bit less for the 2000 retiree than for some retirees in the 1960s, this is hardly reassuring with further analysis based on the required future asset returns needed for sustainability. Our findings cast doubt as to whether the 4 percent withdrawal rate rule will be sustainable for turn-of-the-century retirees

Design, Development, Implementation, and On-orbit Performance of the Dynamic Ionosphere CubeSat Experiment Mission

Funded by the NSF CubeSat and NASA ELaNa programs, the Dynamic Ionosphere CubeSat Experiment (DICE) mission consists of two 1.5U CubeSats which were launched into an eccentric low Earth orbit on October 28, 2011. Each identical spacecraft carries two Langmuir probes to measure ionospheric in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a science grade magnetometer to measure in-situ DC and AC magnetic fields. Given the tight integration of these multiple sensors with the CubeSat platforms, each of the DICE spacecraft is effectively a “sensorsat” capable of comprehensive ionospheric diagnostics. The use of two identical sensor-sats at slightly different orbiting velocities in nearly identical orbits permits the de-convolution of spatial and temporal ambiguities in the observations of the ionosphere from a moving platform. In addition to demonstrating nanosat-based constellation science, the DICE mission is advancing a number of groundbreaking CubeSat technologies including miniaturized mechanisms and high-speed downlink communications

Improved selection criteria for HII regions, based on IRAS sources

We present new criteria for selecting HII regions from the Infrared Astronomical Satellite (IRAS) Point Source Catalogue (PSC), based on an HII region catalogue derived manually from the all-sky Wide-field Infrared Survey Explorer (WISE). The criteria are used to augment the number of HII region candidates in theMilkyWay. The criteria are defined by the linear decision boundary of two samples: IRAS point sources associated with known HII regions, which serve as theHII region sample, and IRAS point sources at high Galactic latitudes, which serve as the non-H II region sample. Amachine learning classifier, specifically a support vector machine, is used to determine the decision boundary. We investigate all combinations of four IRAS bands and suggest that the optimal criterion is log (F60/F12) ? (-0.19 × log (F100/F25) + 1.52), with detections at 60 and 100 µm. This selects 3041 HII region candidates from the IRAS PSC. We find that IRAS HII region candidates show evidence of evolution on the two-colour diagram. Merging the WISE HII catalogue with IRAS HII region candidates, we estimate a lower limit of approximately 10 200 for the number of HII regions in the Milky Way