Aluminum 2195 T8 Gore Development for Space Launch System Core and Upper Stage

Gores are pie-shaped panels that are welded together to form the dome ends of rocket fuel tanks as shown in figure 1. Replacing aluminum alloy 2219 with aluminum (Al)-lithium (Li) alloy 2195 as the Space Launch System (SLS) cryogenic tank material would save enormous amounts of weight. In fact, it has been calculated that simply replacing Al 2219 gores with Al 2195 gores on the SLS core stage domes could save approximately 3,800 pound-mass. This is because the Al-Li 2195 alloy exhibits both higher mechanical properties and lower density than the SLS baseline Al 2219 alloy. Indeed, the known advantages of Al 2195 led to its use as a replacement for Al 2219 in the shuttle external tank program. The required thicknesses of Al 2195 gores for either SLS core stage tanks or upper stage tanks will depend on the specific design configurations. The required thicknesses or widths may exceed the current experience base in the manufacture of such gores by the stretch-forming process. Accordingly, the primary objective of this project was to enhance the formability of Al 2195 by optimizing the heat treatment and stretch-forming process for gore thicknesses up to 0.75 inches, which envelop the maximum expected gore thicknesses for SLS tank configurations

Measurement of Diffusion Coefficients of Dopants in Ge and Si Melts

No abstract availabl

A Theological Study of Baptism and the Lord\u27s Supper as Expressed at the Hanover Convention of the Lutheran World Federation

The study which here presents the theology of Baptism and the Lord’s Supper expressed at the Hannover Convention of the Lutheran World Federation is an outgrowth of the writer\u27s concern to know what was said on theological matters by members of the Lutheran World Federation assembled in their first official convention as a federation of Lutherans

Transient Effects in Planar Solidification of Dilute Binary Alloys

The initial transient during planar solidification of dilute binary alloys is studied in the framework of the boundary integral method that leads to the non-linear Volterra integral governing equation. An analytical solution of this equation is obtained for the case of a constant growth rate which constitutes the well-known Tiller's formula for the solute transient. The more physically relevant, constant ramping down temperature case has been studied both numerically and analytically. In particular, an asymptotic analytical solution is obtained for the initial transient behavior. A numerical technique to solve the non-linear Volterra equation is developed and the solution is obtained for a family of the governing parameters. For the rapid solidification condition, growth rate spikes have been observed even for the infinite kinetics model. When recirculating fluid flow is included into the analysis, the spike feature is dramatically diminished. Finally, we have investigated planar solidification with a fluctuating temperature field as a possible mechanism for frequently observed solute trapping bands

TACL - a timeshared hybrid system for control laboratories

A generalized control-system model encompassing a wide variety of systems has been programmed on the analog portion of a hybrid computation system. Five terminals with storage oscilloscopes are con nected to the hybrid computer and are serviced on a round-robin basis. The generalized system can be configured in milliseconds to a specific problem by setting the values of the digital coefficient units and switches of the analog system. A library of specific problems is kept on the system's digital disk. Students use the system by referencing a problem in the library and entering parameter values to define the problem from their terminals. The per-solution time varies with the time scale seZect ed, but averages around a few hundred milliseconds. A user-oriented compiler helps the instructor define new problems to be added. Digital values are assigned by the student to select ed parameters of specific problems, and families of curves representing system performance as a function of control settings may be displayed on the student's terminal. The terminals also display digital data and alphanumerical information.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68305/2/10.1177_003754977502500203.pd

Di-mu-iodido-bis{[(R)-(+)-2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl-kappa2P,P']copper(I)}0.67-hydrate

Peer reviewe

Copper(I) complexes of 8-(diphenylphosphanyl-oxy)-quinoline : Photophysics, structures and reactivity

Copper(I) complexes are studied for various potential applications due to their luminescence properties. However, issues have been identified regarding the stability of heteroleptic compounds. As a novel strategy, we propose to modify existing copper(I) complexes by introduction of molecular bridges between the different ligands. We report the synthesis and chemical properties of the complexes of 8-(diphenylphosphanyl-oxy)quinoline (POQ), a combination of a phosphine and a N-heterocycle with CuX (X = Cl, Br, I and SCN). The photophysical properties of the materials were studied. However, all four compounds were found to be labile in solution upon contact with trace amounts of water. Two POQ complexes and the decomposition products were identified as tetraphenyldiphosphoxane complexes with single crystal X-ray diffraction. We propose a design rule to prevent this behavior in future development steps. (C) 2017 Published by Elsevier B.V.Peer reviewe

Materials Science on the International Space Station

No abstract availabl

On Favorable Thermal Fields for Detached Bridgman Growth

The thermal fields of two Bridgman-like configurations, representative of real systems used in prior experiments for the detached growth of CdTe and Ge crystals, are studied. These detailed heat transfer computations are performed using the CrysMAS code and expand upon our previous analyses [14] that posited a new mechanism involving the thermal field and meniscus position to explain stable conditions for dewetted Bridgman growth. Computational results indicate that heat transfer conditions that led to successful detached growth in both of these systems are in accordance with our prior assertion, namely that the prevention of crystal reattachment to the crucible wall requires the avoidance of any undercooling of the melt meniscus during the growth run. Significantly, relatively simple process modifications that promote favorable thermal conditions for detached growth may overcome detrimental factors associated with meniscus shape and crucible wetting. Thus, these ideas may be important to advance the practice of detached growth for many materials