MEGA16 - Computer program for analysis and extrapolation of stress-rupture data

The computerized form of the minimum commitment method of interpolating and extrapolating stress versus time to failure data, MEGA16, is described. Examples are given of its many plots and tabular outputs for a typical set of data. The program assumes a specific model equation and then provides a family of predicted isothermals for any set of data with at least 12 stress-rupture results from three different temperatures spread over reasonable stress and time ranges. It is written in FORTRAN 4 using IBM plotting subroutines and its runs on an IBM 370 time sharing system

Turbine engine Hot Section Technology (HOST) project

The Hot Section Technology (HOST) Project is a NASA-sponsored endeavor to improve the durability of advanced gas turbine engines for commercial and military aircraft. Through improvements in the analytical models and life prediction systems, designs for future hot section components , the combustor and turbine, will be more accurately analyzed and will incorporate features required for longer life in the more hostile operating environment of high performance engines

Interpolation and Extrapolation of Creep Rupture Data by the Minimum Commitment Method. Part 3: Analysis of Multiheats

The Minimum Commitment Method was applied to two sets of data for which multiple heat information was available. For one alloy, a 304 stainless steel studied in Japan, data on nine well characterized heats were used, while for a proprietary low alloy carbon steel studied in the United Kingdom data were available on seven heats - in many cases to very long rupture times. For this preliminary study no instability factors were used. It was discovered that heat-to-heat variations would be accounted for by introducing heat identifiers in the form A + B log sigma where sigma is the stress and the constants A and B depend only on the heat. With these identifiers all the data could be collapsed onto a single master curve, even though there was considerable scatter among heats. Using these identifiers together with the average behavior of all heats made possible the determination of an accurate constitutive equation for each individual heat. Two basic approaches are discussed for applying the results of the analysis

An introduction to NASA's turbine engine hot section technology (HOST) project

An overview of research to develop and improve the accuracy of current analysis methods so that increased durability can be designed into future engines is presented. Emphasis is placed on improved accuracy in life prediction. Component design, including description of the thermal and aerodynamic environments, the material's mechanical response, the interactions between environmental and structural response, and high temperature instrumentation capable of measuring near-engine environment effects are addressed. Component tests, improved modeling of the physical phenomena, and tests to verify the proved models are also discussed

Toward improved durability in advanced combustors and turbines: Progress in the prediction of thermomechanical loads

NASA is sponsoring the Turbine Engine Hot Section Technology (HOST) Project to address the need for improved durability in advanced combustors and turbines. Analytical and experimental activities aimed at more accurate prediction of the aerothermal environment, the thermomechanical loads, the material behavior and structural responses to such loading, and life predictions for high temperature cyclic operation have been underway for several years and are showing promising results. Progress is reported in the development of advanced instrumentation and in the improvement of combustor aerothermal and turbine heat transfer models that will lead to more accurate prediction of thermomechanical loads

La acción local para proteger a las comunidades en Nigeria

Iniciativas colaborativas y creativas en Nigeria ayudaron a proteger a las comunidades locales de muchos de los efectos de la violencia de Boko Haram. Pero cuando los organismos de ayuda internacional llegaron, ignoraron esos esfuerzos

Protein Particle Formation for Pulmonary Delivery

Recently, there has been an increased focus on inhalation therapies in drug delivery research. It has been proven that many medications and vaccines can be inhaled in particle form, which has certain advantages. Respiratory diseases such as asthma and emphysema can be more directly treated by administering medications to the lungs. Even for non-respiratory conditions, the large internal surface area of the lungs provides a very effective means for entering the bloodstream. Particle processing of pharmaceuticals is commonly done in batches with toxic organic solvents; a large portion of drug processing costs come from multiple solvent separation steps. Another problem with batch processes is that it is difficult to achieve consistent particle size and distribution. To overcome these issues, many innovative particle engineering methods have been developed using supercritical fluids as the solvents or anti-solvents. One such process, ASES (Aerosol Solvent Extraction System), has proven to yield particles of the ideal size to administer by inhalation (1-5 microns) and uniform distribution necessary for reliable dosage. Also, a supercritical fluid such as CO2, which is gaseous at room temperature, completely separates upon returning to ambient conditions. This process has great potential to increase yield, increase throughput, and decrease processing costs. This purpose of this study is to find trends for development of mathematical models and to show potential for realistically scaling up for industrial production. Key processing variables include drug solution flow rate, antisolvent flow rate, temperature, and pressure. Preliminary experiments explored the effects of these variables on particle morphology using Bovine Serum Albumin (BSA) as a less-expensive model system. It was found that increasing the system pressure decreases the size of the primary particles, but increases agglomeration due to frequency of particle collisions. Increasing the system temperature also decreases the particle size, which indicates the need for a balance between achieving high density and high viscosity in the antisolvent. For this system, solution and antisolvent flow rates appear to have the most pronounced effect on the resulting particles. This would indicate that turbulence and other mass transfer effects are the most important. Furthering studies with BSA on a larger scale will help to understand the effects of scale on the important processing variables. Advisor: Dr. David Tomask

Rosa pratincola Greene

There is more or less confusion as to the name and description of the wild rose of the prairies. A study of this problem was undertaken more particularly with reference to our Iowa forms

The Disparate Effects of Strategic Manipulation

When consequential decisions are informed by algorithmic input, individuals may feel compelled to alter their behavior in order to gain a system's approval. Models of agent responsiveness, termed "strategic manipulation," analyze the interaction between a learner and agents in a world where all agents are equally able to manipulate their features in an attempt to "trick" a published classifier. In cases of real world classification, however, an agent's ability to adapt to an algorithm is not simply a function of her personal interest in receiving a positive classification, but is bound up in a complex web of social factors that affect her ability to pursue certain action responses. In this paper, we adapt models of strategic manipulation to capture dynamics that may arise in a setting of social inequality wherein candidate groups face different costs to manipulation. We find that whenever one group's costs are higher than the other's, the learner's equilibrium strategy exhibits an inequality-reinforcing phenomenon wherein the learner erroneously admits some members of the advantaged group, while erroneously excluding some members of the disadvantaged group. We also consider the effects of interventions in which a learner subsidizes members of the disadvantaged group, lowering their costs in order to improve her own classification performance. Here we encounter a paradoxical result: there exist cases in which providing a subsidy improves only the learner's utility while actually making both candidate groups worse-off--even the group receiving the subsidy. Our results reveal the potentially adverse social ramifications of deploying tools that attempt to evaluate an individual's "quality" when agents' capacities to adaptively respond differ.Comment: 29 pages, 4 figure