Determination of hydrogen permeability in commercial and modified superalloys

The results of hydrogen permeability measurements on several iron- and cobalt-base alloys as well as on two long-ranged ordered alloys over the range of 705 to 870 C (1300 to 1600 F) are summarized. The test alloys included wrought alloys N-155, IN 800, A-286, 19-9DL, and 19-9DL modifications with aluminum, niobium, and misch metal. In addition, XF-818, CRM-6D, SA-F11, and HS-31 were evaluated. Two wrought long-range ordered alloys, Ni3Al and (Fe,Ni)3(V,Al) were also evaluated. All tests were conducted at 20.7 MPa pressure in either pure and/or 1% CO2-doped H2 for test periods as long as 133 h. Detailed analyses were conducted to determine the relative permeability rankings of these alloys and the effect of doping, exit surface oxidation, specimen design variations, and test duration on permeability coefficient, and permeation activation energies were determined. The two long-range ordered alloys had the lowest permeability coefficients in pure H2 when compared with the eight commercial alloys and their modifications. With CO2 doping, significant decrease in permeability was observed in commercial alloys--no doped tests were conducted with the long-range ordered alloys

Basking behavior of Emydid turtles (Chysemys picta marginata, Graptemys geographica, and Trachemys scripta elegans) in an urban landscape

Basking is common in emydid turtles and is generally accepted to be in thermoregulatory behavior. In 2004, we quantified and described the basking behavior of turtles in the Central Canal of Indianapolis. This canal system runs through an urban landscape that is dominated by fragmented woodlots, residential areas. and commercial areas. We observed that basking turtles exhibited variable basking behavior. with spatial and temporal shins in basking behavior from east-facing banks in the morning to west-facing banks in the afternoon. Turtles in the Central Canal are subject to frequent disturbance, which altered basking behavior. Many turtles forewent aerial basking on emergent substrates for aquatic basking on vegetation mats. which maintained warmer and more consistent temperatures than either emergent substrates or the surrounding water. Living in an intensively managed urban habitat, turtles in the Central Canal are susceptible to frequent anthropogenic perturbations, and future management should consider the life history and ecology of urban turtle population

Creep-rupture behavior of candidate Stirling engine iron supperalloys in high-pressure hydrogen. Volume 2: Hydrogen creep-rupture behavior

The creep rupture behavior of nine iron base and one cobalt base candidate Stirling engine alloys is evaluated. Rupture life, minimum creep rate, and time to 1% strain data are analyzed. The 3500 h rupture life stress and stress to obtain 1% strain in 3500 h are also estimated

Studies of the use of high-temperature nuclear heat from an HTGR for hydrogen production

The results of a study which surveyed various methods of hydrogen production using nuclear and fossil energy are presented. A description of these methods is provided, and efficiencies are calculated for each case. The process designs of systems that utilize the heat from a general atomic high temperature gas cooled reactor with a steam methane reformer and feed the reformer with substitute natural gas manufactured from coal, using reforming temperatures, are presented. The capital costs for these systems and the resultant hydrogen production price for these cases are discussed along with a research and development program

Experimental Seismic Behavior of the CFS-NEES Building: System-Level Performance of a Full-Scale Two-Story Light Steel Framed Building

In the summer of 2013, testing of two full-scale cold-formed steel (CFS) framed buildings under seismic excitations took place at the Structural Engineering and Earthquake Simulation Lab (SEESL) at the University at Buffalo. Utilizing the twin shake tables, the two-story building specimens were subjected to ground motions from the 1994 Northridge earthquake. These experiments were conducted as a part of the CFS-NEES experimental effort in an attempt to advance cold-formed steel earthquake engineering and design. Two buildings were tested: the first, a specimen constructed with only structural components (CFS-framed gravity walls, shear walls, floor and roof diaphragms, with OSB sheathing on shear walls and diaphragms); the second began with an exact replica of the first building, but saw the addition of various non-structural systems such as gravity wall sheathing, full diaphragm sheathing, interior partition walls, and exterior weatherproofing. Prior to these experiments, little experimental data existed on full building system behavior for CFS framing. This paper presents results on full-system behavior, specifically examining: drifts, acceleration amplification, shear wall behavior, base shear, diaphragm flexibility, damping, and period of vibration. Comparison to the North American specification for CFS, and design recommendations are also provided

Characterizaiton of Cold-formed Steel Shear Wall Behavior under Cyclic Loading for the CFS-NEES Building

The objective of this paper is to provide a full hysteretic characterization of OSB sheathed cold-formed steel (CFS) shear walls designed for use in the National Science Foundation funded Network for Earthquake Engineering Simulation (NEES) project: CFS-NEES (www.ce.jhu.edu/cfsnees). The shear walls were designed for a two-story ledger-framed building (i.e., the CFS-NEES building) that will undergo full-scale shake table testing at the University of Buffalo NEES site. Shear walls in real construction, such as the CFS-NEES building, have details that differ from the shear walls tested and provided for strength prediction in standards such as AISI-S213-07. Differences include: (a) ledger (rim track) members are attached across the interior face of the studs, (b) OSB panel seams, both horizontal and vertical, may not be aligned with the chord studs or only blocked with strap, (c) interior gypsum board is in place, (d) field studs may have a different thickness or grade from the chord studs, and other differences. In this work, these four highlighted differences (a-d) are specifically explored in a series of shear walls tests loaded via cyclic (CUREE) protocols to determine their hysteretic performance. The test results are compared with AISIS213-07 and hysteretic material characterizations utilizing an elastic-plastic model (EEEP) and a model capable of exhibiting pinching in the hysteretic loops (Pinching4). Recommendations are made with respect to modeling the shear walls

Quantum Electrodynamics of the Helium Atom

Using singlet S states of the helium atom as an example, I describe precise calculation of energy levels in few-electron atoms. In particular, a complete set of effective operators is derived which generates O(m*alpha^6) relativistic and radiative corrections to the Schr"odinger energy. Average values of these operators can be calculated using a variational Schr"odinger wave function.Comment: 23 pages, revte