No Man’s Land

This poem is inspired by a set of letters between Jes Jerry Jessen and his sister Helen during his time as a soldier during World War I

Computational simulation of coupled material degradation processes for probabilistic lifetime strength of aerospace materials

The research included ongoing development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subjected to a number of effects or primative variables. These primative variable may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above described constitutive equation using actual experimental materials data together with linear regression of that data, thereby predicting values for the empirical material constraints for each effect or primative variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from the open literature for materials typically of interest to those studying aerospace propulsion system components. Material data for Inconel 718 was analyzed using the developed methodology

Measurement of the threshold sensitivity of honeybees to weak, extremely low-frequency magnetic fields

Experiments reported previously demonstrate that free-flying honeybees are able to detect static intensity fluctuations as weak as 26 nT against the background, earth-strength magnetic field. We report here an extension of this work to weak, alternating fields at frequencies of 10 and 60 Hz. Our results indicate that the sensitivity of the honeybee magnetoreception system decreases rapidly with increasing frequency. At 60 Hz, alternating field strengths above 100 µT are required to elicit discrimination. These results are consistent with biophysical predictions of a magnetite-based magnetoreceptor

Computational simulation of probabilistic lifetime strength for aerospace materials subjected to high temperature, mechanical fatigue, creep and thermal fatigue

This report presents the results of a fourth year effort of a research program, conducted for NASA-LeRC by the University of Texas at San Antonio (UTSA). The research included on-going development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subject to a number of effects or primitive variables. These primitive variables may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above-described constitutive equation using actual experimental materials data together with regression analysis of that data, thereby predicting values for the empirical material constants for each effect or primitive variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from industry and the open literature for materials typically for applications in aerospace propulsion system components. Material data for Inconel 718 has been analyzed using the developed methodology

A Close Look at A Cradle Book

Gratian\u27s Decretum had been a standard work for nearly three centuries before the invention of printing, and hundreds of copies had been laboriously made in manuscript to serve the needs of lawyers, scholars, and all who were concerned with canon law. Because of it\u27s popularity, the Decretum was among the first books issued by Europe\u27s earliest printing presses. It was printed for the first time in the city of Strassburg by Heinrich Eggestein in 1471. That edition must have sold well, for Eggestein issued the same text again the following year. The University of Michigan Law Library copy is of this second printing, dated 1472

Comparison of Maintenance Cost of Medium and Heavy-Duty Alternative Fuel and Diesel Vehicles

Abstract Comparison of Maintenance Cost of Medium and Heavy-Duty Alternative Fuel and Diesel Vehicles Isaac Boyce This study was conducted to provide an in-depth analysis of the differences in maintenance cost with the use of alternative fuel and diesel in medium (MD) and heavy-duty (HD) vehicles. With the push toward lower emissions from transportation vehicles for a cleaner future, the United States of America (US) has incentivized the conversion from the use of conventional fossil fuel, diesel, to lower carbon alternatives. With the increased potential for the use of alternative fuels, an investigation is warranted to understand the differences. This comparison included natural gas, liquified petroleum gas (LPG), and diesel fuel. Diesel fuel is currently the primary fuel source for medium and heavy-duty vehicles of numerous vocations. The vehicles were sampled from the following fields of operation: such as school buses, urban delivery vehicles, and goods movement. The maintenance categories of engine and transmission, as well as exhaust and emission components demonstrated the lowest overall maintenance cost for maintenance of alternative fuel vehicles compared to diesel fuel. Natural gas and LPG powered MD and HD vehicles had consistently lower average maintenance costs in these categories over the useful life of the vehicles. This conclusion is independent of the vehicle’s vocations, for the vocations considered within this study. Highlighting the benefits and drawbacks of converting to alternative fuels for medium and heavy-duty vehicles provides the knowledge needed for end users and fleet managers to make an informed decision when purchasing a new fleet vehicle. The results of this study showed the differences on a cost per mile basis over the life of the vehicle. Natural gas school buses were, on average, 80 percent less expensive to maintain than diesel buses and LPG buses were 62 percent less expensive, on average, compared to diesel. Delivery vehicles favored the alternative fuels with an LPG average maintenance cost that was 23 percent less expensive, on average, than diesel. Alternative fueled goods movement vehicles demonstrated a lower average maintenance cost of 40 percent, on average, compared to diesel fueled vehicles