Kinetics of U(VI) reduction control kinetics of U(IV) reoxidation

For the in situ reductive immobilization of U to be an acceptable strategy for the removal of that element from groundwater, the long-term stability of U(IV) must be determined. Rates of biotransformation of Fe species influence the mineralogy of the resulting products (Fredrickson et al., 2003; Senko et al., 2005), and we hypothesize that the rate of U(VI) reduction influences the mineralogy of resultant U(IV) precipitates. We hypothesize that slower rates of U(VI) reduction will yield U(IV) phases that are more resistant to reoxidation, and will therefore be more stable upon cessation of electron donor addition. U(IV) phases formed by relatively slow reduction may be more crystalline or larger in comparison to their relatively rapidly-formed counterparts (Figure 1), thus limiting the reactivity of slowly-formed U(IV) phases toward various oxidants. The physical location of U(IV) precipitates relative to bacterial cells may also limit the reactivity of biogenic U(IV) phases. In this situation, we expect that precipitation of U(IV) within the bacterial cell may protect U(IV) from reoxidation by limiting physical contact between U(IV) and oxidants (Figure 1). We assessed the effect of U(VI) reduction rate on the subsequent reoxidation of biogenic U(IV) and are currently conducting column scale studies to determine whether U(VI) reduction rate can be manipulated by varying the electron donor concentration used to stimulate U(VI) reduction

Design, fabrication, and certification of advanced modular PV power systems. Annual technical progress report, 8 September 1995--7 September 1996

This report summarizes the activities performed during the first year of a nominal 2-year effort by Solar Electric Specialties Company (SES) under the Photovoltaic Manufacturing Technology (PVMaT) project of the National Photovoltaic Program. The goal of the SES contract is to reduce the installed system life-cycle costs by developing certified and standardized prototype products for two SES product lines--MAPPS{trademark} and Photogenset{trademark}. The MAPPS (modular autonomous PV power supply) systems are used for DC applications up to about a thousand watt-hours. The Photogensets are hybrid PV/generator systems for AC applications. SES expects these products to provide the basis for future commercial product lines of standardized certified, packaged systems

Design, fabrication, and certification of advanced modular PV power systems. Final technical progress report

Solar Electric Specialties Company (SES) has completed a two and a half year effort under the auspices of the US Department of Energy (DOE) PVMaT (Photovoltaic Manufacturing Technology) project. Under Phase 4A1 of the project for Product Driven System and Component Technology, the SES contract ``Design, Fabrication and Certification of Advanced Modular PV Power Systems`` had the goal to reduce installed system life cycle costs through development of certified (Underwriters Laboratories or other listing) and standardized prototype products for two of the product lines, MAPPS{trademark} (Modular Autonomous PV Power Supply) and Photogensets{trademark}. MAPPS are small DC systems consisting of Photovoltaic modules, batteries and a charge controller and producing up to about a thousand watt-hours per day. Photogensets are stand-alone AC systems incorporating a generator as backup for the PV in addition to a DC-AC inverter and battery charger. The program tasks for the two-year contract consisted of designing and fabricating prototypes of both a MAPPS and a Photogenset to meet agency listing requirements using modular concepts that would support development of families of products, submitting the prototypes for listing, and performing functionality testing at Sandia and NREL. Both prototypes were candidates for UL (Underwriters Laboratories) listing. The MAPPS was also a candidate for FM (Factory Mutual) approval for hazardous (incendiary gases) locations

Partitioning and Dynamic Load Balancing of Adaptive Hybrid Grids for Large-Scale Turbulent Flow Simulations

A new partitioning method for complex 3-D hy-brid prismatic/tetrahedral meshes is presented, The method uses an orthogonal recursive bisection ap-proach on a special octree corresponding to the hybrid grid. The octree is generated automatically and han-dles any type of 3-D geometry and domain connectiv-ity. It is employed for partitioning of static, as well as dynamic adaptive meshes. The method yields similar quality partitions for very different geometries, such as a sphere and an aircraft configuration. The strat-egy for load balancing is applied to octants which leads to an efSicient parallel algorithm. Results include par-titioning a hybrid grid around an aircraft configura-tion and octree-based load balancing for a dynamically adapted mesh. The method is applied to large-scale turbulent flow simulations around aircraft configura-tions.

Design, Fabrication, and Certification of Advanced Modular PV Power Systems Final Technical Progress Report

This report describes the overall accomplishments and benefits of Solar Electric Specialties Co. (SES) under this Photovoltaic Manufacturing Technology (PVMaT) subcontract. SES addressed design issues related to their modular autonomous PV power supply (MAPPS) and a mobile photogenset. MAPPS investigations included gel-cell batteries mounted horizontally; redesign of the SES power supply; modified battery enclosure for increased safety and reduced cost; programmable, interactive battery charge controllers; and UL and FM listings. The photogenset systems incorporate generators, battery storage, and PV panels for a mobile power supply. The unit includes automatic oil-change systems for the propane generators, collapsible array mounts for the PV enclosure, and internal stowage of the arrays. Standardizing the products resulted in product lines of MAPPS and Photogensets that can be produced more economically and with shorter lead times, while increasing product quality and reliability. Product assembly and quality control have also been improved and streamlined with the development of standardized assembly processes and QC testing procedures. SES offers the UL-listed MAPPS at about the same price as its previous non-standardized, unlisted products

Parallel Load Balancing for Dynamic Execution Environments

A novel partitioning method which uses orthogonal subdivision of a special octree corresponding to the computational grid is presented. The octree is generated automatically and handles any type of 3-D geometry and domain connectivity. The method is evaluated in terms of execution time as well as the quality of the partitions generated. A parallel load balancing method for dynamic execution environments is also presented. The balancer is designed to work when loads on the processors change due to local mesh adaptation or to changes in the parallel execution system. For the case of a dynamic parallel system, the loads on the processors are determined by run time measurements and the balancer redistributes the work based on these timings. The effectiveness of the balancer is demonstrated via parallel execution times for adaptive turbulent flow simulations