A Bridge and Engine Room Staffing and Scheduling Model for Robust Mission Accomplishment in the Littoral Combat Ships

The Navy’s Littoral Combat Ships were designed to be relatively small surface vessels for operations near a littoral shore theater. These ships were envisioned to be highly automated, networked, agile, stealthy surface combatants capable of defeating anti-access and asymmetric threats in the littorals with minimum manpower. To date, however, some of these ships have experienced significant engineering and propulsion plant failures that impacted mission accomplishment and were attributable, at least in part, to under staffing and over scheduling the human component of the automation-human operational environment. The critical human components on the Littoral Combat Ship are bridge and engine room staffing. Since the engineering plant has been the source of most major failures to date, this project sought to develop an engine room staffing and scheduling model for the Littoral Combat Ship class given a stated set of minimum mission objectives when operating under normal conditions – called “Condition III Underway Steaming”, which is used as the basis for official Navy manning calculations, and to provide recommendations for improved automation-human modeling. A survey of the crew of several LCS ships was conducted and the results were analyzed using exploratory data analysis and multiple joint correspondence analysis. Results of the survey analysis were applied to the design of a joint physical-cognitive-automation workflow analysis of critical procedures and failure modes as they map to four dimensions: fatigue, watch and maintenance tasking, and automation-human interface. Workflow analysis results were then simulated in an IMPRINT model of a typical watch period, and the results were evaluated against the four dimensions of the survey. The project validated that the four dimensions analyzed are indeed worthy of consideration in manpower models, and that IMPRINT has the potential, with a few modifications, to model joint physical-cognitive-automation workflows as an improvement to the current manpower-only models used in Navy ship design by accounting for human factors

Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea Mays)

Stable isotope analysis is being utilized with increasing regularity to examine a wide range of issues (diet, habitat use, migration) in ecology, geology, archaeology, and related disciplines. A crucial component to these studies is a thorough understanding of the range and causes of baseline isotopic variation, which is relatively poorly understood for nitrogen (δ(15)N). Animal excrement is known to impact plant δ(15)N values, but the effects of seabird guano have not been systematically studied from an agricultural or horticultural standpoint.This paper presents isotopic (δ(13)C and δ(15)N) and vital data for maize (Zea mays) fertilized with Peruvian seabird guano under controlled conditions. The level of (15)N enrichment in fertilized plants is very large, with δ(15)N values ranging between 25.5 and 44.7‰ depending on the tissue and amount of fertilizer applied; comparatively, control plant δ(15)N values ranged between -0.3 and 5.7‰. Intraplant and temporal variability in δ(15)N values were large, particularly for the guano-fertilized plants, which can be attributed to changes in the availability of guano-derived N over time, and the reliance of stored vs. absorbed N. Plant δ(13)C values were not significantly impacted by guano fertilization. High concentrations of seabird guano inhibited maize germination and maize growth. Moreover, high levels of seabird guano greatly impacted the N metabolism of the plants, resulting in significantly higher tissue N content, particularly in the stalk.The results presented in this study demonstrate the very large impact of seabird guano on maize δ(15)N values. The use of seabird guano as a fertilizer can thus be traced using stable isotope analysis in food chemistry applications (certification of organic inputs). Furthermore, the fertilization of maize with seabird guano creates an isotopic signature very similar to a high-trophic level marine resource, which must be considered when interpreting isotopic data from archaeological material