Preliminary design study - Oxidizer tank relief valve, Flox-Atlas airborne Final report

Protecting fluorine-liquid oxygen Atlas launch vehicle oxidizer tank against overpressurizatio

Valuing Limited Information in Decision Making Under Uncertainty

Fresh Juice Inc. (FJI) is in the process of determining whether they should launch a new fruit juice in a market that has been relatively stagnant for the last 15 years. Management of FJI is faced with uncertainty surrounding market share, market size, price, and competitor entry. In addition, FJI has the ability to chose between alternative production processes; this choice directly affects the likelihood the investment will return a positive Net Present Value. This case teaches students how to develop a stochastic simulation models given limited information to analyze risk investment decisions.: simulation, uncertainty, strategic management, flexibility, limited information, investment analysis

General N = 1 Supersymmetric Flux Vacua of (Massive) Type IIA String Theory

We derive conditions for the existence of four-dimensional \N=1 supersymmetric flux vacua of massive type IIA string theory with general supergravity fluxes turned on. For an SU(3) singlet Killing spinor, we show that such flux vacua exist only when the internal geometry is nearly-K\"ahler. The geometry is not warped, all the allowed fluxes are proportional to the mass parameter and the dilaton is fixed by a ratio of (quantized) fluxes. The four-dimensional cosmological constant, while negative, becomes small in the vacuum with the weak string coupling.Comment: 4 page

Scorecarding and Heat Mapping: Tools and Concepts for Assessing Strategic Uncertainty

The dramatic changes occurring throughout the agriculture industry are creating new and different uncertainties that result from a turbulent business climate. The objective of this paper is to present a methodology to understand, assess and evaluate, and manage strategic uncertainty. The approach is to present a mental model that frames assessment of strategic uncertainty from a potential and exposure perspective. Scorecarding and heat mapping assessment tools operationalize the mental model. Participants in an executive agribusiness educational workshop applied this mental model and the assessment tools to one of three hypothetical seed companies. The participants then provided an evaluation of the usefulness and effectiveness of uncertainty scorecarding and heat mapping.Uncertainty, scorecarding, strategic uncertainty, heat mapping, potential, exposure, likelihood, Risk and Uncertainty,

Globular Structures of a Helix-Coil Copolymer: Self-Consistent Treatment

A self-consistent field theory was developed in the grand-canonical ensemble formulation to study transitions in a helix-coil multiblock globule. Helical and coil parts are treated as stiff rods and self-avoiding walks of variable lengths correspondingly. The resulting field-theory takes, in addition to the conventional Zimm-Bragg (B.H. Zimm, I.K. Bragg, J. Chem. Phys. 31, 526 (1959)) parameters, also three-dimensional interaction terms into account. The appropriate differential equations which determine the self-consistent fields were solved numerically with finite element method. Three different phase states are found: open chain, amorphous globule and nematic liquid-crystalline (LC) globule. The LC-globule formation is driven by the interplay between the hydrophobic helical segments attraction and the anisotropic globule surface energy of an entropic nature. The full phase diagram of the helix-coil copolymer was calculated and thoroughly discussed. The suggested theory shows a clear interplay between secondary and tertiary structures in globular homopolypeptides.Comment: 26 pages, 30 figures, corrected some typo

Fracture mechanics approach to design analysis of notches, steps and internal cut-outs in planar components

A new approach to the assessment and optimization of geometric stress-concentrating features is proposed on the basis of the correspondence between sharp crack or corner stressfield intensity factors and conventional elastic stress concentration factors (SCFs) for radiused transitions. This approach complements the application of finite element analysis (FEA) and the use of standard SCF data from the literature. The method makes it possible to develop closed-form solutions for SCFs in cases where corresponding solutions for the sharp crack geometries exist. This is helpful in the context of design optimization. The analytical basis of the correspondence is shown, together with the limits on applicability where stress-free boundaries near the stress concentrating feature are present or adjacent features interact. Examples are given which compare parametric results derived from FEA with closed-form solutions based on the proposed method. New information is given on the stress state at a 90° corner or width step, where the magnitude of the stress field intensity is related to that of the corresponding crack geometry. This correspondence enables the user to extend further the application of crack-tip stress-field intensity information to square-cornered steps, external U-grooves, and internal cut-outs

Use of fruit and vegetable waste as growth media in bacterial biocementation for ground improvement applications

The paper investigates the use of mixed fruit and vegetable (FV) waste to extract liquid to grow bacteria. The bacteria will be used to induce biocementation of soils and two metabolic pathways are examined. These are the ureolytic pathway and the carbonic anhydrase pathway (which absorbs CO2). The growing medium produced from fruit and vegetable waste is compared with a commercial growing medium. The results show the feasibility of using FV as a growth medium to successfully biocement soil and coal ash. A typical FV medium contains 3% total sugar and 0.302 mg/100 ml of protein. The results show that vegetable stalks and fruit peel media support the growth of both ureolytic bacteria B. licheniformis and U-1, a carbonic anhydrase-producing bacteria. The use of FV waste to grow bacteria leads to a reduction in biocementation costs for ground improvement applications

Role of tyrosine M210 in the initial charge separation of reaction centers of Rhodobacter sphaeroides

Femtosecond spectroscopy was used in combination with site-directed mutagenesis to study the influence of tyrosine M210 (YM210) on the primary electron transfer in the reaction center of Rhodobacter sphaeroides. The exchange of YM210 to phenylalanine caused the time constant of primary electron transfer to increase from 3.5 f 0.4 ps to 16 f 6 ps while the exchange to leucine increased the time constant even more to 22 f 8 ps. The results suggest that tyrosine M210 is important for the fast rate of the primary electron transfer