An Agent Based Model to Assess Crew Temporal Variability During U.S. Navy Shipboard Operations

Understanding the factors that affect human performance variability as well as their temporal impacts is an essential element in fully integrating and designing complex, adaptive environments. This understanding is particularly necessary for high stakes, time-critical routines such as those performed during nuclear reactor, air traffic control, and military operations. Over the last three decades significant efforts have emerged to demonstrate and apply a host of techniques to include Discrete Event Simulation, Bayesian Belief Networks, Neural Networks, and a multitude of existing software applications to provide relevant assessments of human task performance and temporal variability. The objective of this research was to design and develop a novel Agent Based Modeling and Simulation (ABMS) methodology to generate a timeline of work and assess impacts of crew temporal variability during U.S. Navy Small Boat Defense operations in littoral waters. The developed ABMS methodology included human performance models for six crew members (agents) as well as a threat craft, and incorporated varying levels of crew capability and task support. AnyLogic ABMS software was used to simultaneously provide detailed measures of individual sailor performance and of system-level emergent behavior. This methodology and these models were adapted and built to assure extensibility across a broad range of U.S. Navy shipboard operations. Application of the developed ABMS methodology effectively demonstrated a way to visualize and quantify impacts/uncertainties of human temporal variability on both workload and crew effectiveness during U.S. Navy shipboard operations

Utilizing automatically collected data to infer travel behavior : a case study of the East London Line extension

Thesis (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 283-284).Utilizing automatically collected data sources, this research strengthens the understanding of changes in user travel behavior caused by the introduction of the extended East London Line (ELL) into London's public transportation network. A recently developed method for inferring all Oyster users' origins and destinations on the public transportation system, and linking trip segments into full journeys, enables analysts to study the influence of a major capital investment on the larger public transportation network in great detail over a span of time and geography not available with traditional survey methods. Expanding an Oyster-based origin-destination matrix to represent all users provides estimates of overall ridership and passengers' travel patterns. Careful analysis of the usage of the rail line and other public transportation services in its vicinity provides a new method to infer the passenger demand generated by the new service. Through the creation of a large user panel (made up of over 54,000 Oyster users with active cards in April 2010 and who travelled on the ELL in October 2011), this thesis studies changes in journey frequency, travel time, journey distance, public transportation mode share, and access distance by comparing journeys made before and after the introduction of the extended ELL.by Kevin J. Muhs.S.M.in Transportatio

A morphometric comparison of the Namib and southwest Kalahari dunefields using ASTER GDEM data

The increased availability of digital elevation models and satellite image data enable testing of morphometric relationships between sand dune variables (dune height, spacing and equivalent sand thickness), which were originally established using limited field survey data. These long-established geomorphological hypotheses can now be tested against very much larger samples than were possible when available data were limited to what could be collected by field surveys alone. This project uses ASTER global digital elevation model (GDEM) data to compare morphometric relationships between sand dune variables in the southwest Kalahari dunefield to those of the Namib sand sea, to test whether the relationships found in an active sand sea (Namib) also hold for the fixed dune system of the nearby southwest Kalahari. The data show significant morphometric differences between the simple linear dunes of the Namib sand sea and the southwest Kalahari; the latter do not show the expected positive relationship between dune height and spacing. The southwest Kalahari dunes show a similar range of dune spacings, but they are less tall, on average, than the Namib sand sea dunes. There is a clear spatial pattern to these morphometric data; the tallest and most closely spaced dunes are towards the southeast of the Kalahari dunefield; and this is where the highest values of equivalent sand thickness result. We consider the possible reasons for the observed differences and highlight the need for more studies comparing sand seas and dunefields from different environmental settings

A design and performance analysis for the Hot Primary Heat Exchanger (HPX) using numerical analysis

The Hot Primary Heat Exchanger (HPX), a key component of the ThermoAcoustic Life Sciences Refrigerator, consists of a tube and fin design. The tubing is bent into a serpentine pattern and overlayed on a screen of copper fins. The serpentine pattern results in several flow reversals and complex internal flow geometries within the heat exchanger. The fins are not consistently of uniform length and generally have heat rejection at both ends. This design results in a forced-cooled, single stack cold plate configuration with unequal temperatures at each end of the fin. The analysis of this configuration requires a methodology based upon the existence of an adiabatic point somewhere along the fin between the prime surfaces. Once the location of this adiabatic point is known, the cold plate may be treated on the basis of two isolated surfaces having fins with adiabatic tips.http://archive.org/details/adesignndperform109457512U.S. Navy (U.S.N.) author

Automated Electric Transportation: A Way to Meet America\u27s Critical Issues

President Obama has set national goals to reduce the production of greenhouse gases in this country. It is now Congress’s turn to follow the president’s lead and provide legislative leadership in dealing with this country’s petroleum use, greenhouse gas production, and rebuilding of our transportation infrastructure. This paper describes one concept that would help America deal with all three of these critical issues. It is a bold, new approach to transportation in America that integrates energy, vehicle, highway, and communication infrastructures into a flexible, convenient, and automated electric transportation (AET) system. AET has the unique potential to simultaneously and dramatically reduce petroleum use, carbon emissions, air pollution, traffic congestion, and highway crashes in the United States while creating millions of new jobs. It could save the U.S. economy trillions of dollars over the next few decades and enable GDP growth rivaling the economic value derived from constructing the Interstate Highway System

Temporal Variability In Human Performance: A Systematic Literature Review

Objective The objective of this paper is to conduct a systematic literature review on the evolution and current status of research into temporal variation impacts on human task performance. Methods This review details the findings from a systematic review of peer reviewed literature identified via keyword searches in ISI Web of Science, Engineering Village Compendex, IEEE Explore, PsycINFO, Defense Technical Information Center (DTIC) online, ProQuest Dissertations & Theses, and Google Scholar. Proceeding articles, peer reviewed journals, cited grey literature, and government technical reports relevant to temporal variability in human performance were identified and used in this review. Both statistical and contents analysis were conducted in this paper. Results Results suggest that the current state of research in human temporal variability is evolving but still has shortcomings in terms of integrating all aspects of interplay between the physical and cognitive components of human response. In light of this, research supporting the sustained development and use of refined cognitive-physical models is gaining momentum and sensible efforts to use task analysis tools that provide integration of both the cognitive and physical components of human response are underway. Conclusions This article identifies that although considerable advancements have been made in understanding the temporal variability of human performance, substantial research regarding the factors affecting it, their impacts, and the practical implications are still required. Originality/value This study is unique in both the breadth and range of literature considered regarding the factors affecting temporal variability in human performance as well as their implications. Successful consideration of these elements in human-centered complex adaptive systems establishes mechanisms for efficient and effective manpower and risk mitigation planning

Soil formation rates on silicate parent material in alpine environments: Different approaches–different results?

High-mountain soils develop in particularly sensitive environments. Consequently, deciphering and predicting what drives the rates of soil formation in such environments are a major challenge. In terms of soil production or formation from chemical weathering, the predominating perception for high-mountain soils and cold environments is often that the chemical weathering ‘portion’ of soil development is temperature-inhibited, often to the point of non-occurrence. Several concepts exist to determine long-term rates of soil formation and development. We present three different approaches: (1) quantification of soil formation from minimally eroded soils of known age using chronosequences (known surface age and soil thickness — SAST), (2) determination of soil residence times (SRT) and production rates through chemical weathering using (un)stable isotopes (e.g. 230Th/234U activity ratios), and (3) a steady state approach using cosmogenic isotopes (e.g. 10Be). For each method, data from different climate zones, and particularly from high-mountains (alpine environment), are compared. The SAST and steady state approach give quite similar results for alpine environments (European Alps and the Wind River Range (Rocky Mountains, USA)). Using the SRT approach, soil formation rates in mountain areas (but having a temperate climate) do not differ greatly from the SAST and steady state approaches. Independent of the chosen approach, the results seem moderately comparable. Soil formation rates in high-mountain areas (alpine climate) range from very low to extremely high values and show a clear decreasing tendency with time. Very young soils have up to 3–4 orders of magnitude higher rates of development than old soils (105 to 106 yr). This apparently is a result of kinetic limits on weathering in regions having young surfaces and supply limits to weathering on old surfaces. Due to the requirement for chemical weathering to occur, soil production rates cannot be infinitely high. Consequently, a speed limit must exist. In the literature, this limit has been set at about 320 to 450 t/km2/a. Our results from the SAST approach show, however, that in alpine areas soil formation easily reaches rates of up to 800– 2000 t/km2/a. These data are consistent with previous studies in mountain regions demonstrating that particularly young soils intensively weather, even under continuous seasonal snowpack and, thus, that the concept of ‘temperature-controlled’ soil development (soil-forming intervals) in alpine regions must be reconsidered