Deformation induced phase transformation in Zr3Al studied by transmission electron microscopy

Die Herstellung nanokristalliner Materialien durch extreme plastische Verformung grobkristalliner Strukturen wird seit rund zwei Jahrzehnten intensiv erforscht. Trotz des Potentials, Materialeigenschaften durch Nanostrukturierung zu verändern, wurden nanokristalline intermetallische Legierungen noch nicht umfassend untersucht. In dieser Arbeit wird die intermetallische Verbindung Zr3Al, die die geordnete L12 Struktur aufweist, zum ersten Mal extrem plastisch verformt und die dabei auftretenden Strukturänderungen untersucht. Die dabei zum Einsatz kommenden Verformungsmethoden sind Hochdrucktorsion sowie wiederholtes Kaltwalzen und Falten. Hochdrucktorsion bei Raumtemperatur führt zu nanokristallinen Proben und ermöglicht einen systematischen Vergleich zwischen Zr3Al und anderen hochverformten Verbindungen, die ursprünglich die L12 Struktur aufweisen. Dieser Vergleich liefert ein tieferes Verständnis des Einflusses der verschiedenen Versetzungsaufspaltungsmechanismen auf die Kornverfeinerung und die verformungsinduzierten Phasenumwandlungen. Eine raster- und durchstrahlungselektronenmikroskopische Betrachtung der verformten Proben ermöglicht die Untersuchung von strukturellen Inhomogenitäten ab der atomaren Skala bis hin zu einer Längenskala, die der Probengröße entspricht. Dabei werden Abweichungen von einem idealen Torsionsexperiment sowie der Wechsel der Verformungsmechanismen mit zunehmender Kornverfeinerung erklärt. Die Verformung von Zr3Al durch wiederholtes Kaltwalzen und Falten führt zu amorphen Proben. Damit wird der Einfluss der verschiedenen Verformungsmethoden auf die Sättigungsstruktur gezeigt. Weiters werden kalorimetrische Messungen angewandt, um Auskunft über die thermische Stabilität und das Kristallisationsverhalten des durch Walzen amorphisierten Materials zu erhalten. Die unvollständige Amorphisierung, die Restnanokristallite im Material verursacht, begünstigt während des Aufheizens der Probe die Bildung einer nanokristallinen Phase. Härtemessungen und Röntgendiffraktometrie ergänzen all diese Studien durch Informationen über die mechanischen und integralen strukturellen Eigenschaften. Durch die Untersuchung verschiedener Verformungsmethoden sowie der Inhomogenitäten der Verformung durch Hochdrucktorsion kann diese Arbeit einen wesentlichen Beitrag zum physikalischen Verständnis der Strukturänderungen von intermetallischen Verbindungen durch extreme plastische Verformung liefern.The production of nanocrystalline materials by severe plastic deformation of coarse grained structures has been attracting a lot of research interest for the last two decades. Despite the potential to change and tailor material properties by nanostructuring, there are rather limited data available for nanocrystalline intermetallic alloys. In this work, severe plastic deformation of the ordered L12 structured intermetallic compound Zr3Al and the study of deformation induced structural changes are conducted for the first time. Zr3Al is heavily deformed by the methods of high pressure torsion and repeated cold rolling with intermediate foldings. The deformation by high pressure torsion at room temperature leads to nanocrystalline samples and allows a systematic comparison to other L12 compounds subjected to high pressure torsion. This comparison facilitates the understanding of the influence of different dislocation dissociation mechanisms on the grain refinement characteristics and on the deformation induced phase transitions of these materials. A multi-scale analysis of the deformed Zr3Al samples by transmission and scanning electron microscopy using both plan view and cross section samples allows to assess inhomogeneities from the atomic scale to the scale of the sample, revealing important deviations from the ideal torsion experiment and the change of deformation mechanisms with decreasing grain size. The deformation by repeated cold rolling with intermediate foldings leads to amorphous samples, thus unambiguously showing the different effects of the deformation methods on the saturation structure. In addition, calorimetric measurements yield information about the thermal stability and the crystallization behaviour of the material amorphized by rolling. It is shown that imperfect amorphization involving residual nanocrystallites facilitates the crystallization of a fine nanocrystalline structure. Hardness measurements by microindentation and X-ray diffractometry supplement these studies by yielding information on the mechanical properties and integral structural properties of deformed samples, respectively. By studying different deformation methods and the inhomogeneity of the deformation by high pressure torsion, this work is an important contribution to the physical understanding of structural changes of intermetallic compounds by severe plastic deformation

Physicochemical Characteristics of the Hyporheic Zone Affect Redd Site Selection of Chum and Fall Chinook Salmon, Columbia River.

Chum salmon (Oncorhynchus keta) may historically have been the most abundant species of Columbia River salmon, contributing as much as 50% of the total biomass of all salmon in the Pacific Ocean prior to the 1940's (Neave 1961). By the 1950's, however, run sizes to the Columbia River dropped dramatically and in 1999 the National Marine Fisheries Service (NMFS) listed Columbia River chum salmon as threatened under the Endangered Species Act (ESA; NMFS 1999). Habitat degradation, water diversions, harvest, and artificial propagation are the major human-induced factors that have contributed to the species decline (NMFS 1998). Columbia River chum salmon spawn exclusively in the lower river below Bonneville Dam, including an area near Ives Island. The Ives Island chum salmon are part of the Columbia River evolutionary significant unit (ESU) for this species, and are included in the ESA listing. In addition to chum salmon, fall chinook salmon (O. tshawytscha) also spawn at Ives Island. Spawning surveys conducted at Ives Island over the last several years show that chum and fall chinook salmon spawned in clusters in different locations (US Fish and Wildlife Service and Washington Department of Fish and Wildlife, unpublished data). The presence of redd clusters suggested that fish were selecting specific habitat features within the study area (Geist and Dauble 1998). Understanding the specific features of these spawning areas is needed to quantify the amount of habitat available to each species so that minimum flows can be set to protect fish and maintain high quality habitat

SpaceCube Version 1.5

SpaceCube 1.5 is a high-performance and low-power system in a compact form factor. It is a hybrid processing system consisting of CPU (central processing unit), FPGA (field-programmable gate array), and DSP (digital signal processor) processing elements. The primary processing engine is the Virtex- 5 FX100T FPGA, which has two embedded processors. The SpaceCube 1.5 System was a bridge to the SpaceCube 2.0 and SpaceCube 2.0 Mini processing systems. The SpaceCube 1.5 system was the primary avionics in the successful SMART (Small Rocket/Spacecraft Technology) Sounding Rocket mission that was launched in the summer of 2011. For SMART and similar missions, an avionics processor is required that is reconfigurable, has high processing capability, has multi-gigabit interfaces, is low power, and comes in a rugged/compact form factor. The original SpaceCube 1.0 met a number of the criteria, but did not possess the multi-gigabit interfaces that were required and is a higher-cost system. The SpaceCube 1.5 was designed with those mission requirements in mind. The SpaceCube 1.5 features one Xilinx Virtex-5 FX100T FPGA and has excellent size, weight, and power characteristics [443 in. (approx. = 10108 cm), 3 lb (approx. = 1.4 kg), and 5 to 15 W depending on the application]. The estimated computing power of the two PowerPC 440s in the Virtex-5 FPGA is 1100 DMIPS each. The SpaceCube 1.5 includes two Gigabit Ethernet (1 Gbps) interfaces as well as two SATA-I/II interfaces (1.5 to 3.0 Gbps) for recording to data drives. The SpaceCube 1.5 also features DDR2 SDRAM (double data rate synchronous dynamic random access memory); 4- Gbit Flash for storing application code for the CPU, FPGA, and DSP processing elements; and a Xilinx Platform Flash XL to store FPGA configuration files or application code. The system also incorporates a 12 bit analog to digital converter with the ability to read 32 discrete analog sensor inputs. The SpaceCube 1.5 design also has a built-in accelerometer. In addition, the system has 12 receive and transmit RS- 422 interfaces for legacy support. The SpaceCube 1.5 processor card represents the first NASA Goddard design in a compact form factor featuring the Xilinx Virtex- 5. The SpaceCube 1.5 incorporates backward compatibility with the Space- Cube 1.0 form factor and stackable architecture. It also makes use of low-cost commercial parts, but is designed for operation in harsh environments

SpaceCube Mini

This version of the SpaceCube will be a full-fledged, onboard space processing system capable of 2500+ MIPS, and featuring a number of plug-andplay gigabit and standard interfaces, all in a condensed 3x3x3 form factor [less than 10 watts and less than 3 lb (approximately equal to 1.4 kg)]. The main processing engine is the Xilinx SIRF radiation- hardened-by-design Virtex-5 FX-130T field-programmable gate array (FPGA). Even as the SpaceCube 2.0 version (currently under test) is being targeted as the platform of choice for a number of the upcoming Earth Science Decadal Survey missions, GSFC has been contacted by customers who wish to see a system that incorporates key features of the version 2.0 architecture in an even smaller form factor. In order to fulfill that need, the SpaceCube Mini is being designed, and will be a very compact and low-power system. A similar flight system with this combination of small size, low power, low cost, adaptability, and extremely high processing power does not otherwise exist, and the SpaceCube Mini will be of tremendous benefit to GSFC and its partners. The SpaceCube Mini will utilize space-grade components. The primary processing engine of the Mini is the Xilinx Virtex-5 SIRF FX-130T radiation-hardened-by-design FPGA for critical flight applications in high-radiation environments. The Mini can also be equipped with a commercial Xilinx Virtex-5 FPGA with integrated PowerPCs for a low-cost, high-power computing platform for use in the relatively radiation- benign LEOs (low-Earth orbits). In either case, this version of the Space-Cube will weigh less than 3 pounds (.1.4 kg), conform to the CubeSat form-factor (10x10x10 cm), and will be low power (less than 10 watts for typical applications). The SpaceCube Mini will have a radiation-hardened Aeroflex FPGA for configuring and scrubbing the Xilinx FPGA by utilizing the onboard FLASH memory to store the configuration files. The FLASH memory will also be used for storing algorithm and application code for the PowerPCs and the Xilinx FPGA. In addition, it will feature highspeed DDR SDRAM (double data rate synchronous dynamic random-access memory) to store the instructions and data of active applications. This version will also feature SATA-II and Gigabit Ethernet interfaces. Furthermore, there will also be general-purpose, multi-gigabit interfaces. In addition, the system will have dozens of transceivers that can support LVDS (low-voltage differential signaling), RS-422, or SpaceWire. The SpaceCube Mini includes an I/O card that can be customized to meet the needs of each mission. This version of the SpaceCube will be designed so that multiple Minis can be networked together using SpaceWire, Ethernet, or even a custom protocol. Scalability can be provided by networking multiple SpaceCube Minis together. Rigid-Flex technology is being targeted for the construction of the SpaceCube Mini, which will make the extremely compact and low-weight design feasible. The SpaceCube Mini is designed to fit in the compact CubeSat form factor, thus allowing deployment in a new class of missions that the previous SpaceCube versions were not suited for. At the time of this reporting, engineering units should be available in the summer 2012

Modelling of Innovative SANEX Process Maloperations

The innovative (i-) SANEX process for the separation of minor actinides from PUREX highly active raffinate is expected to employ a solvent phase comprising 0.2M TODGA with 5 v/v% 1-octanol in an inert diluent. An initial extract / scrub section would be used to extract trivalent actinides and lanthanides from the feed whilst leaving other fission products in the aqueous phase, before the loaded solvent is contacted with a low acidity aqueous phase containing a sulphonated bis-triazinyl pyridine ligand (BTP) to effect a selective strip of the actinides, so yielding separate actinide (An) and lanthanide (Ln) product streams. This process has been demonstrated in lab scale trials at Jülich (FZJ). The SACSESS (Safety of ACtinide SEparation proceSSes) project is focused on the evaluation and improvement of the safety of such future systems. A key element of this is the development of an understanding of the response of a process to maloperations. It is only practical to study a small subset of possible maloperations experimentally and consideration of the majority of maloperations entails the use of a validated dynamic model of the process. Distribution algorithms for HNO3, Am, Cm and the lanthanides have been developed and incorporated into a dynamic flowsheet model that has, so far, been configured to correspond to the extract-scrub section of the i-SANEX flowsheet trial undertaken at FZJ in 20131. Comparison is made between the steady state model results and experimental results. Results from modelling of low acidity and high temperature maloperations are presented

Evaluation of Salmon Spawning below the Four Lowermost Columbia River Dams, 2004-2005 Annual Report.

Since FY 2000, scientists at Pacific Northwest National Laboratory (PNNL) have conducted research to assess the extent of spawning by chum (Oncorhynchus keta) and fall Chinook (O. tshawytscha) salmon in the lower mainstem Columbia River. Their work supports a larger Bonneville Power Administration (BPA) project aimed at characterizing the physical habitat used by mainstem fall Chinook and chum salmon populations. Multiple collaborators in addition to PNNL are involved in the BPA project--counterparts include the Washington Department of Fish and Wildlife (WDFW), U.S. Fish and Wildlife Service (USFWS), Pacific States Marine Fisheries Commission (PSMFC), U.S. Geological Survey (USGS), and Oregon Department of Fish and Wildlife (ODFW). Data resulting from the individual tasks each agency conducts are providing a sound scientific basis for developing strategies to operate the Federal Columbia River Power System (FCRPS) in ways that will effectively protect and enhance the chum and fall Chinook salmon populations--both listed as threatened under the Endangered Species Act. Fall Chinook salmon, thought to originate from Bonneville Hatchery, were first noted to be spawning downstream of Bonneville Dam by biologists from the WDFW in 1993. Known spawning areas include gravel beds on the Washington side of the river near Hamilton Creek and Ives Island. Limited spawning ground surveys were conducted in the area around Ives and Pierce islands during 1994 through 1997. Based on these surveys, fall Chinook salmon were believed to be spawning successfully in this area. In addition, chum salmon have been documented spawning downstream of Bonneville Dam. In FY 1999, BPA Project No. 1999-003 was initiated by the WDFW, ODFW, and the USFWS to characterize the variables associated with physical habitat used by mainstem fall Chinook and chum salmon populations and to better understand the effects of hydropower project operations on spawning and incubation. Pacific Northwest National Laboratory was asked to join the study in FY 2000, during which its initial efforts were focused on (1) investigating the interactions between groundwater and surface water near fall Chinook and chum salmon spawning areas and (2) locating and mapping deepwater fall Chinook salmon spawning areas. In FY 2001, an additional task was added to provide support to the WDFW for analysis of juvenile salmon stranding data. The work PNNL has conducted since then continues to address these same three issues. The overall project is subdivided into a series of tasks, with each agency taking the lead on a task; WDFW leads the adult task, ODFW leads the juvenile task, and the USFWS leads the habitat task. All three tasks are designed to complement each other to achieve the overall project goal. Study results from PNNL's work contribute to all three tasks. This report documents the studies and tasks performed by PNNL during FY 2005. Chapter 1 provides a description of the deepwater redd searches conducted adjacent to Pierce and Ives islands and documents the search results and analysis of findings. Chapter 2 documents the collection of data on riverbed and river temperatures, from the onset of spawning to the end of emergence, and the provision of those data in-season to fisheries management agencies to assist with emergence timing estimates. Technical assistance provided to the WDFW in evaluation of stranding data is summarized in Chapter 3

Boom‐bust dynamics in biological invasions: towards an improved application of the concept

Boom‐bust dynamics – the rise of a population to outbreak levels, followed by a dramatic decline – have been associated with biological invasions and offered as a reason not to manage troublesome invaders. However, boom‐bust dynamics rarely have been critically defined, analyzed, or interpreted. Here, we define boom‐bust dynamics and provide specific suggestions for improving the application of the boom‐bust concept. Boom‐bust dynamics can arise from many causes, some closely associated with invasions, but others occurring across a wide range of ecological settings, especially when environmental conditions are changing rapidly. As a result, it is difficult to infer cause or predict future trajectories merely by observing the dynamic. We use tests with simulated data to show that a common metric for detecting and describing boom‐bust dynamics, decline from an observed peak to a subsequent trough, tends to severely overestimate the frequency and severity of busts, and should be used cautiously if at all. We review and test other metrics that are better suited to describe boom‐bust dynamics. Understanding the frequency and importance of boom‐bust dynamics requires empirical studies of large, representative, long‐term data sets that use clear definitions of boom‐bust, appropriate analytical methods, and careful interpretations

Spacecube V2.0 Micro Single Board Computer

A single board computer system radiation hardened for space flight includes a printed circuit board having a top side and bottom side; a reconfigurable field programmable gate array (FPGA) processor device disposed on the top side; a connector disposed on the top side; a plurality of peripheral components mounted on the bottom side; and wherein a size of the single board computer system is not greater than approximately 7 cm.times.7 cm

Conceptual Spawning Habitat Model to Aid in ESA Recovery Plans for Snake River Fall Chinook Salmon, 2002-2003 Annual Report.

The goal of this project is to develop a spawning habitat model that can be used to determine the physical habitat factors that are necessary to define the production potential for fall chinook salmon that spawn in large mainstem rivers like the Columbia River's Hanford Reach and Snake River. This project addresses RPA 155 in the NMFS 2000 Biological Opinion: Action 155: BPA, working with BOR, the Corps, EPA, and USGS, shall develop a program to: (1) Identify mainstem habitat sampling reaches, survey conditions, describe cause-and-effect relationships, and identify research needs; (2) Develop improvement plans for all mainstem reaches; and (3) Initiate improvements in three mainstem reaches. During FY 2003 we continued to collect and analyze information on fall chinook salmon spawning habitat characteristics in the Hanford Reach that will be used to address RPA 155, i.e., items 1-3 above. For example, in FY 2003: (1) We continued to survey spawning habitat in the Hanford Reach and develop a 2-dimensional hydraulic and habitat model that will be capable of predicting suitability of fall chinook salmon habitat in the Hanford Reach; (2) Monitor how hydro operations altered the physical and chemical characteristics of the river and the hyporheic zone within fall chinook salmon spawning areas in the Hanford Reach; (3) Published a paper on the impacts of the Columbia River hydroelectric system on main-stem habitats of fall chinook salmon (Dauble et al. 2003). This paper was made possible with data collected on this project; (4) Continued to analyze data collected in previous years that will ultimately be used to identify cause-and-effect relationships and identify research needs that will assist managers in the improvement of fall chinook habitat quality in main-stem reaches. During FY 2004 we plan to: (1) Complete preliminary reporting and submit papers based on the results of the project through FY 2004. Although we have proposed additional analysis of data be conducted in FY 2005, we anticipate a significant number of key papers being prepared and submitted in FY 2004 which will go toward identifying the data gaps this RPA is intended to address; (2) Make available data from this project for use on Project 2003-038-00 ('Evaluate restoration potential of Snake River fall chinook salmon') which is a BPA-funded project that will start in FY 2004; and (3) Present results of our work at regional and national meetings in order to facilitate technology transfer and information sharing. The objective of this project is to define the production potential of fall chinook salmon that spawn in the Hanford Reach. We will provide fisheries and resource managers with the information they need to determine if the Hanford Reach fall chinook salmon population is indeed healthy, and whether this population will be capable of seeding other satellite populations in the future. We will accomplish this purpose by continuing our on-going research at determining the carrying capacity of the Hanford Reach for producing fall chinook salmon under current operational scenarios, and then begin an assessment of whether the Reach is functioning as a model of a normative river as is widely believed. The product of our research will be a better understanding of the key habitat features for mainstem populations of anadromous salmonids, as well as a better understanding of the measures that must be taken to ensure long-term protection of the Hanford Reach fall chinook population. Although the project was originally funded in FY 1994, it was significantly redefined in FY 2000. At that time five tasks were proposed to accomplish the project objective. The purpose of this progress report is to briefly describe the activities that have been completed on each of the five tasks from FY 2000 through FY 2003