Temporal and spatial inconsistencies of time-split finite-difference schemes

The properties of an implicit time-split algorithm, which utilizes locally one dimensional spatial steps, are examined using the two-dimensional heat conduction equation as the test problem. Both temporal and spatial inconsistencies inherent in the scheme are identified. A consistent, implicit splitting approach is developed. The relationship between this method and other time-split implicit schemes is explained, and stability problems encountered with the method in three dimensions are discussed

A title-gap flow model for use in aerodynamic loads assessment of space shuttle thermal protection system: Parallel gap faces

The problem of predicting aerodynamic loads on the insulating tiles of the space shuttle thermal protection system (TPS) is discussed and seen to require a method for predicting pressure and mass flux in the gaps between tiles. A mathematical model of the tile-gap flow is developed, based upon a slow viscous (Stokes) flow analysis, and is verified against experimental data. The tile-gap pressure field is derived from a solution of the two-dimensional Laplace equation; the mass-flux vector is then calculated from the pressure gradient. The means for incorporating this model into a lumped-parameter network analogy for porous-media flow is given. The means for incorporating this model into a lumped-parameter network analogy for porous-media flow is given. The flow model shows tile-gap mass flux to be very sensitive to the gap width indicating a need for coupling the TPS flow and tile displacement calculation. Analytical and experimental work to improve TPS flow predictions and a possible shuttle TPS hardware modification are recommended

Penn State Get Away Special

Three proposed spaceborne experiments to be conducted by equipment in the Get Away Special (GAS) payload are described. The specific contribution and effect of convection in heat transfer is discussed. Investigations of the surface tension of two liquids in space environment and the problem of liquid slosh in spin stabilized satellites are reviewed

Investigation of the Rocket Induced Flow Field in a Rectangular Duct

Rocket-Based Combined Cycle (RBCC) concepts attempt to improve the performance of launch vehicles at all points in the launch trajectory and make highly reusable launch vehicles a reality. The Aerojet Strutjet RBCC concept consists of a variable geometry duct with internal, vertical struts that functions in ducted rocket, ramjet, scramjet, and pure rocket modes. These struts have rocket and turbine exhaust nozzles imbedded within them. The rocket flows create an ejector effect with the ingested air at subsonic flight velocities. In ramjet and scramjet modes, the fuel rich nozzle flows react with the ingested air producing an afterburner effect. Under a NASA Marshall Space Flight Center contract, the UAH Propulsion Research Center (PRC) has designed and built a Strutjet simulation facility. A scale model of a single strut has been built and is undergoing cold-flow testing to investigate the mixing of the rocket and turbine exhausts with the ingested air. A complementary experimental program is also underway to examine the induced flow-field generated by rocket nozzles confined in a rectangular duct. Characterizing the induced flow behavior is critical to understanding and optimizing the performance of future Strutjet-based RBCC propulsion systems. The proposed paper will present results from the rocket induced flow investigation

The impact of a mobile phone-delivered digital financial education program on financial behavior among Hispanics

We explored the potential of digital financial education programs among Hispanic populations, through the design and evaluation of a mobile phone delivered digital program called Mind Your Money (MYM). This program sought to improve financial knowledge and behavior among low- to-moderate income Hispanics residing in the Greater Los Angeles area. We assessed the program through a randomized controlled trial with a wait-list control group. Our digital financial education program had a higher retention rate than comparable in-person financial coaching programs. We found that our program had a positive statistical significant effect on financial capability. Participants who completed program activities were more likely to have a budget/spending plan and felt more confident about their ability to pay for unexpected expenses

The Digitization of Design and Manufacturing: A State-of-the-Art Report on the Transition from Strategic Vision to Implementation in Industry

Almost a decade ago, the research community embarked on a journey to realize the old vision of Industry 4.0. Part of this vision was to digitize design and manufacturing systems and processes, aimed at advancing their vertical and horizontal integration into decentralized ecosystems across the entire product development value chain. This process was to include the provision of new data-driven operation and business models, advances in cybersecurity, and the development of a bespoke Industry 4.0 workforce. In this paper, the authors review the state-of-the-art in regard to the progress made to date, from initial vision towards implementation in industry. They identify critical research challenges and gaps that need to be addressed to further advance this transition. The paper closes with a strategic perspective on how the authors anticipate Industry 4.0 to evolve over the next 5 years

Tsallis entropy approach to radiotherapy treatments

The biological effect of one single radiation dose on a living tissue has been described by several radiobiological models. However, the fractionated radiotherapy requires to account for a new magnitude: time. In this paper we explore the biological consequences posed by the mathematical prolongation of a model to fractionated treatment. Nonextensive composition rules are introduced to obtain the survival fraction and equivalent physical dose in terms of a time dependent factor describing the tissue trend towards recovering its radioresistance (a kind of repair coefficient). Interesting (known and new) behaviors are described regarding the effectiveness of the treatment which is shown to be fundamentally bound to this factor. The continuous limit, applicable to brachytherapy, is also analyzed in the framework of nonextensive calculus. Also here a coefficient arises that rules the time behavior. All the results are discussed in terms of the clinical evidence and their major implications are highlighted.Comment: 6 figures, accepted for publication to Physica

A Nonparametric Method for the Derivation of α/β Ratios from the Effect of Fractionated Irradiations

Multifractionation isoeffect data are commonly analysed under the assumption that cell survival determines the observed tissue or tumour response, and that it follows a linear-quadratic dose dependence. The analysis is employed to derive the α/β ratios of the linear-quadratic dose dependence, and different methods have been developed for this purpose. A common method uses the so-called Fe plot. A more complex but also more rigorous method has been introduced by Lam et al. (1979). Their method, which is based on numerical optimization procedures, is generalized and somewhat simplified in the present study. Tumour-regrowth data are used to explain the nonparametric procedure which provides α/β ratios without the need to postulate analytical expressions for the relationship between cell survival and regrowth delay