Conducted extensive wind-tunnel tests on parabolic trough solar collectors to determine practical wind loads applicable to structural design for stress and deformation, and local component design for concentrator reflectors.

A lightning protection research and support program was instituted by NREL to help minimize lightning damage to wind turbines in the United States. This paper provides the results of a field test program, an evaluation of protection on selected turbines, and a literature search as well as the dissemination of the accumulated information.

The NREL Wind-Wildlife Impacts Literature Database (WILD) contains citations to more than 1,000 journal articles, government publications, conference proceedings, and other reports.

A PowerPoint presentation given as part of the 2005 Hydrogen Program Review, May 23-26, 2005, in Washington, D.C.

An experimental investigation was conducted for gas generation in contact-handled transuranic (CH TRU) wastes subjected for several years to conditions similar to those expected to occur at the Waste Isolation Pilot Plant (WIPP) should the repository eventually become inundated with brine. Various types of actual CH TRU wastes were placed into 12 corrosion-resistant vessels. The vessels were loosely filled with the wastes, which were submerged in synthetic brine having the same chemical composition as that in the WIPP vicinity. The vessels were also inoculated with microbes found in the Salado Formation at WIPP. The vessels were sealed, purged, and the approximately 750 ml headspace in each vessel was pressurized with nitrogen gas to approximately 146 atmospheres to create anoxic conditions at the lithostatic pressure estimated in the repository were it to be inundated. The temperature was maintained at the expected 30°C. The test program objective was to measure the quantities and species of gases generated by metal corrosion, radiolysis, and microbial activity. These data will assist in the specification of the rates at which gases are produced under inundated repository conditions for use in the WIPP Performance Assessment computer models. These experiments were very carefully designed, constructed, instrumented, and performed. …

We investigated the relationship between ventilation rates and individual work performance in a call center, and controlled for other factors of the indoor environment. We randomized the position of the outdoor air control dampers, and measured ventilation rate, differential (indoor minus outdoor) carbon dioxide ({Delta}CO{sub 2}) concentration, supply air velocity, temperature, humidity, occupant density, degree of under-staffing, shift length, time of day, and time required to complete two different work performance tasks (talking with clients and post-talk wrap-up to process information). {Delta}CO{sub 2} concentrations ranged from 13 to 611 ppm. We used multi-variable regression to model the association between the predictors and the responses. We found that agents performed talk tasks fastest when the ventilation rate was highest, but that the relationship between talk performance and ventilation was not strong or monotonic. We did not find a statistically significant association between wrap-up performance and ventilation rate. Agents were slower at the wrap-up task when the temperature was high (>25.4 C). Agents were slower at wrap-up during long shifts and when the call center was under-staffed.

This report summarizes the deliberations and conclusions of the Workshop on Programming Languages for High Performance Computing (HPCWPL) held at the Sandia CSRI facility in Albuquerque, NM on December 12-13, 2006.

Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band …

The Open Science Grid (OSG) and the Enabling Grids for E-sciencE (EGEE) have a common security model, based on Public Key Infrastructure. Grid resources grant access to users because of their membership in a Virtual Organization (VO), rather than on personal identity. Users push VO membership information to resources in the form of identity attributes, thus declaring that resources will be consumed on behalf of a specific group inside the organizational structure of the VO. Resources contact an access policies repository, centralized at each site, to grant the appropriate privileges for that VO group. Before the work in this paper, despite the commonality of the model, OSG and EGEE used different protocols for the communication between resources and the policy repositories. Hence, middleware developed for one Grid could not naturally be deployed on the other Grid, since the authorization module of the middleware would have to be enhanced to support the other Grid's communication protocol. In addition, maintenance and support for different authorization call-out protocols represents a duplication of effort for our relatively small community. To address these issues, OSG and EGEE initiated a joint project on authorization interoperability. The project defined a common communication protocol and attribute identity profile …

Nano-phosphors of Y3Al5O12:Ce3+ (YAG:Ce) were synthesized with a novel salted sol-gel method, in which aqueous solution of inorganic salts (yttrium/cerium nitrates) were used along with the metal alkoxide precursor, aluminum sec-butoxide, Al(OC4H9)3. YAG single phase was formed at temperature as low as 800 C. Luminescence of YAG:Ce reached the maximum intensity when calcined above 1350C. The SEM image reveals that the grain sizes of the nano-phosphors calcined at 1100 C are in a range of 50-150 nm.

In 2003, the Pacific Northwest National Laboratory (PNNL) evaluated 23 Phase II fish screen sites in the Yakima River Basin as part of a multi-year project for the Bonneville Power Administration on the effectiveness of fish screening devices. PNNL collected data to determine whether velocities in front of the screens and in the bypasses met the Nation Oceanic and Atmospheric Administration Fisheries (NOAA Fisheries, formerly the National Marine Fisheries Service (NMFS)) criteria to promote safe and timely fish passage. In addition, PNNL conducted underwater video surveys to evaluate the environmental and operational conditions of the screen sites with respect to fish passage. Based on evaluations in 2003, PNNL concluded that: (1) In general, water velocity conditions at the screen sites met fish passage criteria set by the National Oceanic and Atmospheric Administration Fisheries. (2) Conditions at most facilities would be expected to provide for safe juvenile fish passage. (3) Conditions at some facilities indicate that operation and/or maintenance should be modified to improve juvenile fish passage conditions. (4) Automated cleaning brushes generally functioned properly; chains and other moving parts were typically well greased and operative. (5) Removal of sediment buildup and accumulated leafy and woody debris could be improved at …

A brief overview of the temperature dependence of yield strength for the different slip systems of MoSi{sub 2} is presented and mechanisms for the yield stress anomaly are discussed. Recent results on the atomistic simulation of the dislocation core structures and mobility are presented next. Finally, we present experimental results on substitutional alloying of polycrystalline MoSi{sub 2} with 1-2 at.% Re, Nb and Al. Re resulted in an order of magnitude increase in compressive strength at 1600 C, Al caused solution softening at near-ambient temperatures, and Nb caused softening at low temperatures and hardening at high temperatures. The quaternary MoSi{sub 2}-Re-Al alloys showed strengthening at elevated temperatures and reduction in flow stress with enhanced plasticity at near-ambient temperatures. The mechanisms of solution hardening and softening are discussed using insight from transmission electron microscopy observations of the dislocation substructures and atomistic simulation results.

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Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) cells require a highly conducting and transparent electrode for optimum device performance. ZnO:Al films grown from targets containing 2.0 wt.% Al2O3 are commonly used for this purpose. Maximum carrier mobilities of these films grown at room temperature are ~20-25 cm2V-1s-1. Therefore, relatively high carrier concentrations are required to achieve the desired conductivity, which leads to free carrier absorption in the near infrared (IR). Lightly doped films (0.05 - 0.2 wt.% Al2O3), which show less IR absorption, reach mobility values greater than 50 cm2V-1s-1 when deposited in H2 partial pressure. We incorporate these lightly doped ZnO:Al layers into CIGS PV cells produced at the National Renewable Energy Laboratory (NREL). Preliminary results show quantum efficiency values of these cells rival those of a past world-record cell produced at NREL that used 2.0 wt.% Al-doped ZnO films. The highest cell efficiency obtained in this trial was 18.1%.

The ability to produce high-performance CdS/CdTe photovoltaic (PV) devices that incorporate high-transparency back contacts for multijunction thin-film PV applications will require an even greater level of understanding than has been required for single-junction devices. This study reports some of our initial investigations at NREL to modify the ZnTe:Cu contact process previously developed for single-junction applications for optimal use as a transparent back contact. We have succeeded in producing devices incorporating a transparent ZnTe:Cu/ITO/metal-grid contact that demonstrates nominally identical light I-V (LIV) performance to the ZnTe:Cu/Ti contact used in single-junction devices. However, we have determined that the transparent conducting oxide (TCO), CdS, CdTe, and ZnTe:Cu layers are all factors in the optical absorption within the device. Finally, we have concluded that optimizing the transparent ZnTe:Cu contact for use with NREL-produced device material will require a more detailed understanding of the evolution of the junction region during the contact process.