High concentration suspended sediment measurments using acontinuous fiber optic in-stream transmissometer (open access)

High concentration suspended sediment measurments using acontinuous fiber optic in-stream transmissometer

Suspended sediment loads mobilized during high flow periods in rivers and streams are largely uncharacterized. In smaller and intermittent streams, a large storm may transport a majority of the annual sediment budget. Therefore monitoring techniques that can measure high suspended sediment concentrations at semi-continuous time intervals are needed. A Fiber optic In-stream Transmissometer (FIT) is presented for continuous measurement of high concentration suspended sediment in storm runoff. FIT performance and precision were demonstrated to be reasonably good for suspended sediment concentrations up to 10g/L. The FIT was compared to two commercially available turbidity devices and provided better precision and accuracy at both high and low concentrations. Both turbidity devices were unable to collect measurements at concentrations greater than 4 g/L. The FIT and turbidity measurements were sensitive to sediment particle size. Particle size dependence of transmittance and turbidity measurement poses the greatest problem for calibration to suspended sediment concentration. While the FIT was demonstrated to provide acceptable measurements of high suspended sediment concentrations, approaches to real-time suspended sediment detection need to address the particle size dependence in concentration measurements.
Date: May 26, 2004
Creator: Campbell, Chris G.; Laycak, Danny T.; Hoppes, William; Tran,Nguyen T. & Shi, Frank G.
System: The UNT Digital Library
Rating energy efficiency and sustainability in laboratories: Results and lessons from the Labs21 program (open access)

Rating energy efficiency and sustainability in laboratories: Results and lessons from the Labs21 program

Laboratories are very energy intensive, with significant opportunities for improved efficiency. However, their inherent complexity and variety makes benchmarking of their energy and environmental performance a unique and challenging task. Furthermore, laboratories have a myriad of health and safety requirements that significantly affect energy use, adding complexity to their benchmarking. The Labs21 program, a joint program of the US EPA and US DOE, has developed two resources specifically for assessing laboratory energy and environmental performance: (1) An energy benchmarking tool which allows users to compare laboratories using a standard set of building and system level energy use metrics. (2) The Environmental Performance Criteria (EPC) a point-based rating system that builds on the LEED(TM) green building rating system, designed to score overall environmental performance. In this paper, for each of these tools we present the underlying methodology and results from their use. For the benchmarking tool, we contrast our approach, which includes a simulation model-based component, with those used for other building types. We also present selected results from data collection and analysis of about 40 private and public sector laboratory facilities. In the case of the EPC, we describe variations from the LEED standard, focusing on the energy credits. Finally, …
Date: May 26, 2004
Creator: Mathew, Paul; Sartor, Dale; van Geet, Otto & Reilly, Sue
System: The UNT Digital Library
Reactive Transport Modeling of Cap Rock Integrity During Natural and Engineered CO2 Storage (open access)

Reactive Transport Modeling of Cap Rock Integrity During Natural and Engineered CO2 Storage

Long-term cap rock integrity represents the single most important constraint on the long-term isolation performance of natural and engineered CO{sub 2} storage sites. CO{sub 2} influx that forms natural accumulations and CO{sub 2} injection for EOR/sequestration or saline-aquifer disposal both lead to concomitant geochemical alteration and geomechanical deformation of the cap rock, enhancing or degrading its seal integrity depending on the relative effectiveness of these interdependent processes. Using our reactive transport simulator (NUFT), supporting geochemical databases and software (GEMBOCHS, SUPCRT92), and distinct-element geomechanical model (LDEC), we have shown that influx-triggered mineral dissolution/precipitation reactions within typical shale cap rocks continuously reduce microfracture apertures, while pressure and effective-stress evolution first rapidly increase then slowly constrict them. For a given shale composition, the extent of geochemical enhancement is nearly independent of key reservoir properties (permeability and lateral continuity) that distinguish EOR/sequestration and saline-aquifer settings and CO{sub 2} influx parameters (rate, focality, and duration) that distinguish engineered disposal sites and natural accumulations, because these characteristics and parameters have negligible (indirect) impact on mineral dissolution/precipitation rates. In contrast, the extent of geomechanical degradation is highly dependent on these reservoir properties and influx parameters because they effectively dictate magnitude of the pressure perturbation; specifically, initial geomechanical …
Date: May 26, 2004
Creator: Johnson, J. W.; Nitao, J. J. & Morris, J. P.
System: The UNT Digital Library
Proceedings of Riken BNL Research Center Workshop: Volume 61 Riken-Todai Mini-Workshop on ''Topics in Hadron Physics at RHIC''. Volume 61 (open access)

Proceedings of Riken BNL Research Center Workshop: Volume 61 Riken-Todai Mini-Workshop on ''Topics in Hadron Physics at RHIC''. Volume 61

The RIKEN-TODAI Mini-Workshop on ''Topics in Hadron Physics at RHIC'' was held on March 23rd and 24th, 2064 at the Nishina Memorial Hall of RIKEN, Wako, Saitama, Japan, sponsored by RIKEN (Institute of Physical and Chemical Research) and TODAI (University of Tokyo). The workshop was planned when we learned that two distinguished theorists in hadron physics, Professors L. McLerran and S.H. Lee, would be visiting TODAI and/or RIKEN during the week of March 22-26. We asked them to give key talks at the beginning of the workshop and attend the sessions consisting of talks by young theorists in RIKEN, TODAI and other institutes in Japan and they kindly agreed on both. Considering the JPS meeting scheduled from March 27 through 30, we decided to have a.one-and-half-a-day workshop on March 23 and 24. The purpose of the workshop was to offer young researchers an opportunity to learn the forefront of hadron physics as well as to discuss their own works with the distinguished theorists.
Date: May 26, 2004
Creator: En'yo, H.; Hamagaki, H.; Hatsuda, T.; Watanaba, Y. & Yazaki, K.
System: The UNT Digital Library
Superbend upgrade of the Advanced Light Source (open access)

Superbend upgrade of the Advanced Light Source

The Advanced Light Source (ALS) is a third generation synchrotron light source located at Lawrence Berkeley National Laboratory (LBNL). There was an increasing demand at the ALS for additional high brightness hard x-ray beamlines in the 7 to 40 keV range. In response to that demand, the ALS storage ring was modified in August 2001. Three 1.3 Tesla normal conducting bending magnets were removed and replaced with three 5 Tesla superconducting magnets (Superbends). The radiation produced by these Superbends is an order of magnitude higher in photon brightness and flux at 12 keV than that of the 1.3 Tesla bends, making them excellent sources of hard x-rays for protein crystallography and other hard x-ray applications. At the same time the Superbends did not compromise the performance of the facility in the VUV and soft x-ray regions of the spectrum. The Superbends will eventually feed 12 new beamlines greatly enhancing the facility's capability and capacity in the hard x-ray region. The Superbend project is the biggest upgrade to the ALS storage ring since it was commissioned in 1993. In this paper we present an overview of the Superbend project, its challenges and the resulting impact on the ALS.
Date: May 26, 2004
Creator: Robin, D.; Krupnick, J.; Schlueter, R.; Steier, C.; Marks, S.; Wang, B. et al.
System: The UNT Digital Library
An algebraic sub-structuring method for large-scale eigenvaluecalculation (open access)

An algebraic sub-structuring method for large-scale eigenvaluecalculation

We examine sub-structuring methods for solving large-scalegeneralized eigenvalue problems from a purely algebraic point of view. Weuse the term "algebraic sub-structuring" to refer to the process ofapplying matrix reordering and partitioning algorithms to divide a largesparse matrix into smaller submatrices from which a subset of spectralcomponents are extracted and combined to provide approximate solutions tothe original problem. We are interested in the question of which spectralcomponentsone should extract from each sub-structure in order to producean approximate solution to the original problem with a desired level ofaccuracy. Error estimate for the approximation to the small esteigen pairis developed. The estimate leads to a simple heuristic for choosingspectral components (modes) from each sub-structure. The effectiveness ofsuch a heuristic is demonstrated with numerical examples. We show thatalgebraic sub-structuring can be effectively used to solve a generalizedeigenvalue problem arising from the simulation of an acceleratorstructure. One interesting characteristic of this application is that thestiffness matrix produced by a hierarchical vector finite elements schemecontains a null space of large dimension. We present an efficient schemeto deflate this null space in the algebraic sub-structuringprocess.
Date: May 26, 2004
Creator: Yang, C.; Gao, W.; Bai, Z.; Li, X.; Lee, L.; Husbands, P. et al.
System: The UNT Digital Library
Real Time Pricing and the Real Live Firm (open access)

Real Time Pricing and the Real Live Firm

Energy economists have long argued the benefits of real time pricing (RTP) of electricity. Their basis for modeling customers response to short-term fluctuations in electricity prices are based on theories of rational firm behavior, where management strives to minimize operating costs and optimize profit, and labor, capital and energy are potential substitutes in the firm's production function. How well do private firms and public sector institutions operating conditions, knowledge structures, decision-making practices, and external relationships comport with these assumptions and how might this impact price response? We discuss these issues on the basis of interviews with 29 large (over 2 MW) industrial, commercial, and institutional customers in the Niagara Mohawk Power Corporation service territory that have faced day-ahead electricity market prices since 1998. We look at stories interviewees told about why and how they respond to RTP, why some customers report that they can't, and why even if they can, they don't. Some firms respond as theorized, and we describe their load curtailment strategies. About half of our interviewees reported that they were unable to either shift or forego electricity consumption even when prices are high ($0.50/kWh). Reasons customers gave for why they weren't price-responsive include implicit value placed on …
Date: May 26, 2004
Creator: Moezzi, Mithra; Goldman, Charles; Sezgen, Osman; Bharvirkar, Ranjit & Hopper, Nicole
System: The UNT Digital Library