A simple, mass balance model of carbon flow in a controlled ecological life support system

Internal cycling of chemical elements is a fundamental aspect of a Controlled Ecological Life Support System (CELSS). Mathematical models are useful tools for evaluating fluxes and reservoirs of elements associated with potential CELSS configurations. A simple mass balance model of carbon flow in CELSS was developed based on data from the CELSS Breadboard project at Kennedy Space Center. All carbon reservoirs and fluxes were calculated based on steady state conditions and modelled using linear, donor-controlled transfer coefficients. The linear expression of photosynthetic flux was replaced with Michaelis-Menten kinetics based on dynamical analysis of the model which found that the latter produced more adequate model output. Sensitivity analysis of the model indicated that accurate determination of the maximum rate of gross primary production is critical to the development of an accurate model of carbon flow. Atmospheric carbon dioxide was particularly sensitive to changes in photosynthetic rate. The small reservoir of CO2 relative to large CO2 fluxes increases the potential for volatility in CO2 concentration. Feedback control mechanisms regulating CO2 concentration will probably be necessary in a CELSS to reduce this system instability

Utilization of the water soluable fraction of wheat straw as a plant nutrient source

Recovery of water soluble, inorganic nutrients from the inedible portion of wheat was found to be an effective means of recycling nutrients within hydroponic systems. Through aqueous extraction (leaching), 60 percent of the total inorganic nutrient weight was removed from wheat straw and roots, although the recovery of individual nutrients varied. Leaching also removed about 20 percent of the total organic carbon from the biomass. In terms of dry weight, the leachate was comprised of approximately 60 percent organic and 40 percent inorganic compounds. Direct use of wheat straw leachate in static hydroponic systems had an inhibitory effect on wheat growth, both in the presence and absence of microorganisms. Biological treatment of leachate either with a mixed microbial community or the oyster mushroom Pleurotus ostreatus L., prior to use in hydroponic solutions, significantly reduced both the organic content and the inhibitory effects of the leachate. The inhibitory effects of unprocessed leachate appear to be a result of rapidly acting phytotoxic compounds that are detoxified by microbial activity. Leaching holds considerable promise as a method for nutrient recycling in a Controlled Ecological Life Support System (CELSS)

Evaluation of shuttle solid rocket booster case materials. Corrosion and stress corrosion susceptibility of several high temperature materials

Candidate alloys for the Shuttle Solid Rocket Booster (SRB) case were tested under simulated service conditions to define subcritical flaw growth behavior under both sustained and cyclic loading conditions. The materials evaluated were D6AC and 18 Ni maraging steel, both heat treated to a nominal yield strength of 1380 MN/sq m (200 ksi). The sustained load tests were conducted by exposing precracked, stressed specimens of both alloys to alternate immersion in synthetic sea water. It was found that the corrosion and stress corrosion resistance of the 18 Ni maraging steel were superior to that of the D6AC steel under these test conditions. It was also found that austenitizing temperature had little influence on the threshold stress intensity of the D6AC. The cyclic tests were conducted by subjecting precracked surface-flawed specimens of both alloys to repeated load/thermal/environmental profiles which were selected to simulate the SRB missions. It was found that linear removal operations that involve heating to 589 K (600 F) cause a decrease in cyclic life of D6AC steel relative to those tests conducted with no thermal cycling

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Static and forward speed tests were made in a 40 multiplied by 80 foot wind tunnel of a large-scale, ejector-powered V/STOL aircraft model. Modifications were made to the model following earlier tests primarily to improve longitudinal acceleration capability during transition from hovering to wingborne flight. A rearward deflection of the fuselage augmentor thrust vector was shown to be beneficial in this regard. Other augmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also showed negligible influence on the performance of the wing and of the fuselage augmentor

Formation and properties of new Ni-based amorphous alloys with critical casting thickness up to 5 mm

New Ni-based bulk metallic glasses were synthesized in NixCua−xTiyZrb−yAl10 (a~b~45 at.%) system, based on a ternary alloy, Ni45Ti20Zr35. The additions of Al and Cu greatly increase the glass-forming ability (GFA). The best GFA is located around Ni40Cu5Ti16.5Zr28.5Al10, from which fully amorphous samples of up to 5 mm thickness were successfully fabricated by an injection mold casting method. These alloys exhibit high glass-transition temperatures Tg ~ 760 to 780 K, and relatively wide undercooled-liquid regions ΔT (defined by the difference between Tg and the first crystallization temperature Tx1 upon heating) ~ 40–50 K. Mechanical tests on these alloys show quite high Vicker's Hardness ~ 780 to 862 kg/mm^2, Young's modulus ~ 111 to 134 GPa, shear modulus ~ 40 to 50 GPa and high fracture strength ~ 2.3 to 2.4 GPa. The effect of small Si-addition and a discrepancy between GFA and ΔT are also reported. The exceptional GFA and the all-metallic compositions give these new alloys excellent promise for both scientific and engineering applications

Bulk metallic glass formation in binary Cu-rich alloy series – Cu100−xZrx (x=34, 36, 38.2, 40 at.%) and mechanical properties of bulk Cu64Zr36 glass

The compositional dependence of a glass-forming ability (GFA) was systematically studied in a binary alloy series Cu100−xZrx (x=34, 36, 38.2, 40 at.%) by the copper mold casting method. Our results show the critical casting thickness jumps from below 0.5 mm to above 2 mm when x changes from 34 to 36 while further increase in x reduces the critical casting thickness. The best glass former Cu64Zr36 does not correspond to either the largest undercooled liquid region (ΔT=Tx1−Tg, where Tg is the glass transition temperature, and Tx1 is the onset temperature of the first crystallization event upon heating) or the highest reduced glass transition temperature (Trg=Tg/Tl, where Tl is the liquidus temperature). Properties of bulk amorphous Cu64Zr36 were measured, yielding a Tg ~ 787 K, Trg ~ 0.64, ΔT ~ 46 K, Hv (Vicker's Hardness) ~ 742 kg/mm^2, Young's Modulus ~ 92.3 GPa, compressive fracture strength ~ 2 GPa and compressive strain before failure ~ 2.2%

Selection for agronomic traits in hill and row plots of soybeans

Fifty random soybean Glycine max (L.) Merrill lines of maturity group II from intermated populations were used to compare hill and row plot arrangements for selection of superior genotypes for yield, maturity, height, lodging, and phenotypic score. Single, nonbordered hill plots spaced 102 x 102 cm were grown in random and nonrandom complete block designs. The row arrangement was a two-row, nonbordered plot with 69 cm between rows within the plot and 102 cm betwen plots. S(,6) progeny from 50 S(,3) plants were evaluated in hill plots at eight environments and in row plots at 10 environments in Iowa during 1977 and 1978;There was no difference in the effectiveness of selection for yield between random and nonrandom hills. The hill and row plots were equally effective in selecting the top two lines. Actual genetic gain was 2.5 q/ha for random hills, 2.8 q/ha for nonrandom hills, and 3.0 q/ha for rows when the top five lines were considered. Predicted genetic gain per year was 0.64 q/ha for both hill arrangements compared with 0.41 q/ha for rows;Selection for maturity, height, lodging, and phenotypic score was similar in effectiveness for the three plot arrangements. Genotypic correlations of line performance between random and nonrandom hills were nearly perfect and between hills and rows ranged from 0.89 to 0.99 for the four traits;The primary advantage of hills is the reduction in number of years for cultivar development by eliminating the need for a generation of seed increase before yield evaluation in row plots. The use of progeny rows for visual selection and for a seed increase can be replaced by combining visual selection and yield evaluation in replicated hill plots. In environments where intergenotypic competition between single, nonbordered hills is minimal, selection for superior agronomic genotypes can be conducted effectively and efficiently in nonrandom hill plots

Removing the college involvement "research asterisk": Identifying and rethinking predictors of American Indian college student involvement

The purpose of this study was to identify campus environmental predictors of American Indian college student involvement. The American Indian research asterisk, or not including American Indian data, has prevailed over student development research for decades. As a result, student affairs professionals have been limited in their ability to develop evidence-based student development interventions for American Indian student involvement. This study addressed the research asterisk related to American Indian college student involvement through a quantitative multi-institutional study of 99 campuses with a total of 1,931 American Indian respondents. This study confirms many prior research study findings with American Indian college students that were limited in scope and context and where findings lacked transferability. Several key findings emerged from this research study including the importance of pre-college involvement in high school academic clubs and holding leadership positions as significant predictors of college student involvement. Mentor relationships with faculty and student affairs staff were also significant predictors of American Indian student involvement indicating the importance of these types of interactions for this population. Most importantly, a sense of belonging for American Indian students was quantitatively confirmed as a significant predictor of American Indian student involvement. The concept of involvement, however, should not be limited by its historical on-campus context and should be viewed as a dynamic process whereby American Indian students are provided an opportunity to shape an involvement experience that helps to maintain their sense of self and identity while promoting a sense of belonging and collegiate success

Power Motivation and Power Style in Higher Education Administration (Personal Power)

The problem of this study was to determine if a relationship exists between selected personal characteristics of higher education administrators and their perceived levels of power motivation and power style. The techniques of ex post facto research were used in this study. The Power Management Inventory developed by Jay Hall and James Hawker was selected as the appropriate instrument for use in this study. The Power Management Inventory was designed to provide a comparison between one\u27s espoused theory (power motivation) and one\u27s theory in action (power style). A personal data sheet was used to obtain information concerning the personal characteristics of the administrators. The statistical analysis of the data for hypotheses 1 through 24 was intended to determine significant differences in the power motivation types and power style scores of the administrators based on a comparison with selected personal characteristics of those administrators. The differences showing significance in the study warranted the following conclusions: (1) The power motivation of administrators can be directly related to the ages of the administrators. (2) The power style of administrators can be directly related to the ages of administrators. (3) The power motivation of administrators can be directly related to the method by which they were selected for their positions. (4) The power style of administrators can be directly related to the method by which they were selected to their positions. (5) The power style of administrators can be directly related to the number of years of service in their positions