| A Performance Analysis of the Optimized Link State Routing Protocol Using Voice Traffic Over Mobile Ad Hoc Networks |
22 Mar 2012 |
126 pages |
| Authors:
Andre Wolf; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
 | Mobile ad hoc networks (MANETs) have grown in popularity over the past decade and are increasingly considered for time-sensitive multimedia applications. The impact of various routing protocols on voice traffic using different IEEE 802.11 extensions has been investigated via analytical models, simulations and experimental test beds. Many studies determined that optimized link state routing (OLSR) is a suitable routing protocol to support voice over internet protocol (VoIP) conversations. This research ... |
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| Methane Dual Expander Aerospike Nozzle Rocket Engine |
22 Mar 2012 |
131 pages |
| Authors:
Michael D Moen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The Air Force Institute of Technology (AFIT), working to meet requirements set by the Air Force Research Laboratory's Next Generation Engine (NGE) initiative, is developing upper stage rocket models. The current path of investigation focuses on combining a dual expander cycle with an aerospike nozzle, or the Dual Expander Aerospike Nozzle (DEAN) using methane fuel. The design process will rely heavily on AFIT's previous work, which focused on the development ... |
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| Silicon Carbide Capacitive High Temperature MEMS Strain Transducer |
22 Mar 2012 |
101 pages |
| Authors:
Richard P Weisenberger; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| Air Force Research Lab Air Vehicles directorate performs research on hypersonic vehicles. To verify materials or designs of hypersonic vehicles, they have a need to measure strain at temperatures exceeding 700 C. Strain sensors have the ability to measure strain. Strain is the deformation of materials due to internal stresses in a material. Internal stresses occur when a material is subjected to a force. Traditional strain sensors use Piezoresistive effects ... |
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| A Trained Network Solution for Multi-State Structural Awareness |
12 Mar 2012 |
32 pages |
| Authors:
Michael Todd; Zhu Mao; CALIFORNIA UNIV REGENTS SAN DIEGO LA JOLLA CA
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| This project considered a rapid condition assessment test using transmissibility measurements in vibration tests. A hypothesis test is established that detects changes in transmissibility estimations over time that indicate target failure mode occurrence; in this project, fastener preload loss was the first considered failure mode for simple representations of satellite structures, and later consideration was given to cracking in beam-like rotor structures. Inherent to this procedure (or any structural health ... |
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| The Distribution of Solar Wind Speeds During Solar Minimum: Calibration for Numerical Solar Wind Modeling Constraints on the Source of the Slow Solar Wind (Postprint) |
05 Mar 2012 |
14 pages |
| Authors:
S L McGregor; W J Hughes; C N Arge; M J Owens; D Odstreil; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
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| It took the solar polar passage of Ulysses in the early 1990s to establish the global structure of the solar wind speed during solar minimum. However, it remains unclear if the solar wind is composed of two distinct populations of solar wind from different sources (e.g., closed loops which open up to produce the slow solar wind) or if the fast and slow solar wind rely on the superradial expansion ... |
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| Near Earth Object Detection Using a Poisson Statistical Model for Detection on Images Modeled from the Panoramic Survey Telescope and Rapid Response System |
Mar 2012 |
87 pages |
| Authors:
Curtis J Peterson; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The purpose of this research effort is to develop, simulate, and test a new algorithm to detect Near Earth Objects (NEOs) using a Likelihood Ratio Test (LRT) based on a Poisson statistical model for the arrival of photons. One detection algorithm currently in use is based on a Gaussian approximation of the arrival of photons, and is compared to the proposed Poisson model. The research includes three key components. The ... |
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| Analysis and Design of Complex Network Environments |
Mar 2012 |
103 pages |
| Authors:
Sean Warnick; Daniel Zappala; BRIGHAM YOUNG UNIV PROVO UT DEPT OF COMPUTER SCIENCE
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| This research takes a fresh view of complex network environments and answers fundamental questions about 1) how to model them, 2) the design of experiments necessary to discover their structure (and thus adapt system inputs to optimize the resulting performance), and 3) the relationship between network structure to vulnerability and attack. Specifically, this work explores these issues in the context of both wireless mesh and bio-chemical reaction networks. Although wildly ... |
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| A Division-Dependent Compartmental Model for Computing Cell Numbers in CFSE-based Lymphocyte Proliferation Assays |
12 Feb 2012 |
35 pages |
| Authors:
H T Banks; W C Thompson; Cristina Peligero; Sandra Giest; Jordi Argilaguet; Andreas Meyerhans; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| Some key features of a mathematical description of an immune response are an estimate of the number of responding cells and the manner in which those cells divide, differentiate, and die. The intracellular dye CFSE is a powerful experimental tool for the analysis of a population of dividing cells, and numerous mathematical treatments have been aimed at using CFSE data to describe an immune response [30, 31, 32, 37, 38, ... |
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| Modeling Red Blood Cell and Iron Dynamics in Patients with Chronic Kidney Disease |
10 Feb 2012 |
30 pages |
| Authors:
H T Banks; Karen M Bliss; Hien Tran; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| Chronic kidney disease causes a slow loss of kidney function over time and can eventually lead to End Stage Renal Disease, where a patient must undergo dialysis to remove fluids and wastes from the body. These patients also suffer from a lack of the hormone erythropoietin (EPO), produced in the kidneys, that stimulates red blood cell (RBC) production. Without intervention, patients suffer from anemia. Patients are treated with both EPO ... |
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| Sound Generation in the Interaction of Two Isentropic Vortices |
02 Feb 2012 |
16 pages |
| Authors:
Shuhai Zhang; Hanxin Zhang; Chi-Wang Shu; BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS
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| Through direct numerical simulation (DNS) for the sound generated by the interaction between two isentropic vortices, it is found that the interaction between two vortices with a large difference in their strengths or scales can generate continuous strong noise. The interaction between two isentropic vortices results in the formation of two vortex dipoles, with each vortex dipole containing two vortex cores. If there is a large difference in their initial ... |
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| CHMWTR: A Plasma Chemistry Code for Water Vapor |
01 Feb 2012 |
21 pages |
| Authors:
Daniel F Gordon; Michael H Helle; Theodore G Jones; K Fung; NAVAL RESEARCH LAB WASHINGTON DC BEAM PHYSICS BRANCH
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| The CHMWTR code tracks the evolution of 21 ionic and neutral species in a water vapor plasma excited by a slowly varying electric field. This report discusses the physics of water vapor breakdown and describes the assumptions and methods used in developing the code. The code results are used to determine the breakdown field in water vapor under typical conditions. The conductivity of the plasma is also computed. Since this ... |
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| Modeling and Bayesian Parameter Estimation for Shape Memory Alloy Bending Actuators |
Feb 2012 |
12 pages |
| Authors:
John H Crews; Ralph C Smith; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| In this paper, we employ a homogenized energy model (HEM) for shape memory alloy (SMA) bending actuators. Additionally, we utilize a Bayesian method for quantifying parameter uncertainty. The system consists of a SMA wire attached to a flexible beam. As the actuator is heated, the beam bends, providing endoscopic motion. The model parameters are fit to experimental data using an ordinary least-squares approach. The uncertainty in the fit model parameters ... |
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| Frontiers in Anisotropic Shock-Wave Modeling |
Feb 2012 |
72 pages |
| Authors:
Alexander A Lukyanov; Steven B Segletes; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Studies of anisotropic materials and the discovery of various novel and unexpected phenomena under shock loading has contributed significantly to our understanding of the behavior of condensed matter. The variety of experimental studies for isotropic materials displays systematic patterns, giving basic insights into the underlying physics of anisotropic shock-wave modeling. There are many similarities and significant differences in the phenomena observed for isotropic and anisotropic materials under shock-wave loading. Despite ... |
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| Behavioral and Temporal Pattern Detection Within Financial Data With Hidden Information |
Feb 2012 |
21 pages |
| Authors:
Doron Drusinsky; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| This paper describes a technique for behavioral and temporal pattern detection within financial data, such as credit card and bank account data, where the required information is only partially visible. Typically, transaction amount, transaction date, merchant name and type, and location of transaction are all visible data items, i.e., they are readily available in the financial institutions database. In contrast, the transaction status as a business transaction (using a personal ... |
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| A Compartmental Model for Computing Cell Numbers in CFSE-based Lymphocyte Proliferation Assays |
31 Jan 2012 |
44 pages |
| Authors:
H T Banks; W C Thompson; Cristina Peligero; Sandra Giest; Jordi Argilaguet; Andreas Meyerhans; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
|
| Some key features of a mathematical description of an immune response are an estimate of the number of responding cells and the manner in which those cells divide, differentiate, and die. The intracellular dye CFSE is a powerful experimental tool for the analysis of a population of dividing cells, and numerous mathematical treatments have been aimed at using CFSE data to describe an immune response. Recently, partial differential equation structured ... |
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| The Physics, Chemistry and Dynamics of Explosions |
Jan 2012 |
12 pages |
| Authors:
Elaine S Oran; Forman A Williams; NAVAL RESEARCH LAB WASHINGTON DC LAB FOR COMPUTATIONAL PHYSICS AND FLUID DYNAMICS
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| The motivation for devoting a Theme Issue to explosions is discussed. As subsequent articles in the issue are written with the assumption that the reader has had a certain amount of previous exposure to the subject, some of the history and necessary background information are presented here. The topics on explosions that will be encountered in the remaining articles are previewed. Finally, several important future outstanding research problems, beyond those ... |
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| Winner Takes All: Competing Viruses or Ideas on Fair-Play Networks |
Jan 2012 |
11 pages |
| Authors:
B A Prakash; Alex Beutel; Roni Rosenfeld; Christos Faloutsos; CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE
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| Given two competing products (or memes, or viruses etc.) spreading over a given network, can we predict what will happen at the end, that is, which product will 'win', in terms of highest market share? One may naively expect that the better product (stronger virus) will just have a larger footprint proportional to the quality ratio of the products (or strength ratio of the viruses). However, we prove the surprising ... |
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| Computational Study of the Effect of Slot Orientation on Synthetic Jet-Based Separation Control |
Jan 2012 |
25 pages |
| Authors:
Shawn Aram; Rajat Mittal; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING
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| A computational study is conducted to explore the effect of synthetic jet orientation on boundary layer separation control. A six-to-one aspect-ratio rectangular slot is chosen in the current study and streamwise and spanwise orientations of this slot are analyzed. In the first part of this study, the interaction of the jet with an attached laminar boundary layer for both slot configurations is examined. The dominant feature in the streamwise oriented ... |
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| A Stochastic Multiscale Model for Microstructure Model Reduction |
19 Dec 2011 |
44 pages |
| Authors:
Bin Wen; Nichols Zabaras; CORNELL UNIV ITHACA NY MATERIALS PROCESS DESIGN AND CONTROL LABORATORY (MPDC)
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| The mechanical properties of a deformed workpiece are sensitive to the initial microstructure. Often, the initial microstructure is random in nature and location specific. To model the variability of properties of the workpiece induced by variability in the initial microstructure, one needs to develop a reduced order stochastic input model for the initial microstructure. The location-dependence of microstructures dramatically increases the dimensionality of the stochastic input and causes the curse ... |
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| Modern Social Media and Social Revolutions |
16 Dec 2011 |
127 pages |
| Authors:
Brian L Mayer; ARMY COMMAND AND GENERAL STAFF COLL FORT LEAVENWORTH KS
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| The emergence of social media platforms as a means of communication and information sharing marks a fundamental change to how societies interact. This new form of media played a formative role in the organization of mass uprisings and demonstrations known as the Arab Spring that took place in the Middle East and North Africa in 2011. The study draws data from research in social revolution, social network theory, and mass ... |
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| Ordering of Glass Rods in Nematic and Cholesteric Liquid Crystals |
01 Dec 2011 |
13 pages |
| Authors:
A T Juhl; D Yang; V P Tondiglia; L V Natarajan; T J White; T J Bunning; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| The orientational assembly of glass rods (3 x 15 m) in nematic, twisted nematic, and cholesteric liquid crystal cells was observed and quantified with optical microscopy. At this size, the rods were affected strongly by gravity and sedimented to the bottom of the cells. Temporal visualization of the sedimentation process (induced by flipping the cell over) shed insight into the effect the liquid crystal order had on the glass rod ... |
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| Verification and Validation of the Coastal Modeling System. Report 3: CMS-Flow: Hydrodynamics |
Dec 2011 |
148 pages |
| Authors:
Alejandro Sanchez; Weiming Wu; Tanya M Beck; Honghai Li; III Rosati James; Robert Thomas; Julie D Rosati; Zeki Demirbilek; Mitchell Brown; Christopher Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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| This is the third report, Report 3, in a series of four reports toward the Verification, and Validation (V&V) of the Coastal Modeling System (CMS). All details of the V&V study specific to the hydrodynamic modeling are provided in this report. The primary goal of this study task was to perform a comprehensive assessment of the predictive skills of the CMS-Flow model for a wide range of problems encountered in ... |
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| Large-Scale Online and Real-Time Optimization Problems under Uncertainty |
Dec 2011 |
7 pages |
| Authors:
Patrick Jaillet; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| The main focus of our research is on the fundamental aspects of decision making in the context of uncertain (and possibly very large) data sets revealed in an online fashion. More specifically, we are interested in the intersection and interplay of three main phenomena -- incomplete and uncertain data, online decisions with or without real-time restrictions, and extremely large data sets -- and the corresponding fundamental questions when facing a ... |
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| Development of Photographic Dynamic Measurements Applicable to Evaluation of Flapping Wing Micro Air Vehicles |
Dec 2011 |
86 pages |
| Authors:
Jeremy C Murray; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| Developments in the area of flapping wing micro air vehicles (FWMAVs) of a small size and with limited range. This has lead to a great deal of interest in biomimetric designs based on flapping wing flyers, including the North American Hawkmoth (Manduca Sexta). By utilizing high speed photography and photogrammetry the dynamic flapping of the wing can be characterized for comparison with mathematical models, namely computational fluid dynamics (CFD) and ... |
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| A Small-World Network Model of Disease Transmission |
Dec 2011 |
28 pages |
| Authors:
Karen Cheng; David Crary; J Rodriguez; Darren R Oldson; APPLIED RESEARCH ASSOCIATES INC ARLINGTON VA
|
| The most well-known mathematical models for the investigation of the spread of transmissible infections are compartmental models. These compartments categorize the population according to disease status, susceptibility to infection, etc. and by using coupled differential equations the models can often be solved analytically. But these models assume uniform mixing, i.e. any individual in the population has the same probability of contacting any other individual. These models require very detailed contact ... |
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| Improving Healthcare Facility Locations in Bamyan, Afghanistan |
Dec 2011 |
71 pages |
| Authors:
Yong K Teo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The facility location problem is one of the oldest and most researched operations research problems. In this thesis, we utilize facility location models to determine the optimal locations and types of medical facilities to address the healthcare needs of the people in Bamyan Province, Afghanistan. The staffing levels and materials of a local medical facility in Afghanistan are designed to cope with the healthcare needs of the people. In this ... |
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| Information Selection in Intelligence Processing |
Dec 2011 |
135 pages |
| Authors:
Yuval Nevo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OPERATIONS RESEARCH
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| In many intelligence agencies, the processing of data into usable information ready for analysis poses a significant bottleneck. Typically, much more data is available than can be processed in the limited time available for processing. We formulate the problem faced by an intelligence collection unit when processing incoming raw information for delivery to intelligence analyst as an exploration-exploitation problem: the processor has to choose between exploring for new sources of ... |
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| Shaping Senior Leader Officer Talent: Using a Multi-Dimensional Model of Talent to Analyze the Effect of Personnel Management Decisions and Attrition on the Flow of Army Officer Talent Throughout the Officer Career Model |
Dec 2011 |
13 pages |
| Authors:
Matthew F Dabkowski; Paul Kucik; Samuel H Huddleston; David S Lyle; TRADOC ANALYSIS CENTER FORT LEAVENWORTH KS
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| Army Officer requirements for operational talent decline precipitously with increasing rank. While 80 percent of Junior Officers serve in operational billets, only 20 percent of Senior Leaders serve in operational billets. Yet despite this operational talent requirement inversion, Army development efforts tend to focus disproportionately on building operational talent. Moreover, career progression through the rank of General Officer tends to excessively favor officers who have spent most of their career ... |
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| Modeling and Simulation of Military Tactical Logistics Distribution |
Dec 2011 |
13 pages |
| Authors:
Samir Sebbah; Ahmed Ghanmi; Abdeslem Boukhtouta; DEFENCE RESEARCH AND DEVELOPMENT CANADA OTTAWA (ONTARIO) CENTRE FOR OPERATIONAL RESEARCH AND ANALYSIS
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| The military tactical logistics planning problem addresses the issue of distributing heterogeneous commodities in a theater of operations using a combination of heterogeneous transportation assets such as logistics trucks and tactical helicopters. The Canadian Forces requires a decision support tool to examine the trade-off between the cost of the support and its effectiveness during sustainment operations. In this study, a mathematical optimization algorithm and a simulation module to build cost ... |
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| Air Vehicle Integration and Technology Research (AVIATR). Delivery Order 0013: Nonlinear, Low-Order/Reduced-Order Modeling Applications and Demonstration |
Dec 2011 |
269 pages |
| Authors:
Salvatore L Liguore; Dale M Pitt; Michael J Thomas; Nicholas Gurtowski; BOEING CO ST LOUIS MO
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| Dynamic response analysis tools used by the aerospace industry rely heavily on linear modal frequency response finite element methods. These linear methods are straight forward to use even in the analysis of a complex structural component that require a large number of degrees-of-freedom to model. However, this approach is not suitable for predicting the response of highly loaded thermal/acoustic aircraft structures that may respond in a nonlinear geometric manner. This ... |
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| Social-Aware Data Diffusion in Delay Tolerant MANETs |
30 NOV 2011 |
27 pages |
| Authors:
Yang Zhang; Wei Gao; Guohong Cao; Tom La Porta; Bhaskar Krishnamachari; Arun Iyengar; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF COMPUTER SCIENCE AND ENGINEERING
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| Most existing mobility-assisted data access techniques in delay tolerant mobile ad hoc networks (DT-MANETs) are designed to disseminate data to one or several particular destinations. Different from these works, we study the data diffusion problem which diffuses data among all moving nodes so that the nodes that are interested in this data item can get it easily either from their encountered friend nodes or stranger nodes. To reduce the data ... |
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| Thermal Damage Detection and Characterization in Porous Materials |
30 Nov 2011 |
25 pages |
| Authors:
H T Banks; Amanda K Criner; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| In this effort, we consider damage detection algorithms using thermal probes. The techniques proposed employ models derived from homogenization theory as the model solution in parameter estimation procedures for simulated data for heat flow in a porous medium. We consider data simulated from a model on a perforated domain with isotropic flow and data simulated from a model on a homogeneous domain with anisotropic flow. We report on ordinary least ... |
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| Climate Change, Fuels, and Wildfire |
29 Nov 2011 |
30 pages |
| Authors:
Anthony L Westerling; CALIFORNIA UNIV MERCED CA
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| Climate affects both fuel availability and flammability on multiple time scales, and the relative importance of availability versus flammability as limiting drivers of wildfire activity varies across ecosystem types. Climatic controls on fuel flammability during the peak fire season dominate in dense forests with characteristically infrequent, high severity fire, while the effects of antecedent moisture on the availability of fine surface fuels may also play a role in forests with ... |
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| Increase of Breakthrough Pressure of Cotton Fabric by Fluoropolymer/Fluoroposs Treatment |
29 Nov 2011 |
4 pages |
| Authors:
Kevin R Lamison; Andrew J Guenthner; Joseph M Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| Breakthrough pressure is the external pressure required to force a composite - solid, liquid, vapor - interface to transition irreversibly to the fully wetted - solid liquid - interface. Based on theoretical models, this pressure can be calculated using material properties and an understanding of the surface geometry. The incorporation of low surface energy materials can drastically increase the breakthrough pressure of a material. Cotton fabric was treated in a ... |
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| Heat Transfer Enhancement in Small-Scale Devices: A Collaborative Experimental/Numerical Approach |
28 Nov 2011 |
21 pages |
| Authors:
Gian P Beretta; Pietro Poesio; UNIVERSITA DI BRESCIA (ITALY)
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| The aim of the project has been the analysis of spinodal decomposition of binary liquid mixtures for heat transfer enhancement in micro-devices. The work has followed two main lines and approaches: experimental investigation of heat transfer in small scale heat exchangers and numerical modeling to build a designing tool. For the first approach, the results show a significant increase of heat transfer efficiency up to 100% compared to conventional techniques, ... |
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| Numerical Simulations of Pressure Spikes within a Cylindrical Launch Tube due to a Bursting Helium Flask |
09 Nov 2011 |
16 pages |
| Authors:
Harold D Ladouceur; Benjamin Gould; NAVAL RESEARCH LAB WASHINGTON DC CHEMICAL DYNAMICS AND DIAGNOSTICS BRANCH
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| A numerical model to simulate the bursting of a high-pressure flask of helium gas located within a cylindrical launch tube is described. The model provides an upper estimate for the launch tube wall pressures by assuming that the helium flask failure can be treated as a bursting balloon. The gas dynamic equations for the expansion of the 5000 psig helium region are solved utilizing the finite element program FlexPDE to ... |
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| Observation of Query Pulse Length Dependent Ramsey Interference in Rubidium Vapor Using Pulsed Raman Excitation |
07 Nov 2011 |
15 pages |
| Authors:
G S Pati; F K Fatemi; M S Shahriar; NAVAL RESEARCH LAB WASHINGTON DC OPTICAL SCIENCES DIV
|
| We report observation of query pulse length dependent Ramsey interference (QPLD-RI), using pulsed Raman excitation in rubidium vapor. This is observed when a long, attenuated query pulse is used during pulsed Raman excitation. We explain the physical mechanism behind the QPLDRI using a Bloch vector model. We also use numerical solutions to time-dependent density matrix equations to simulate this interference effect showing qualitative agreement with experimental results. Presence of such ... |
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| TEMPEST Level-0 Theory |
Nov 2011 |
90 pages |
| Authors:
Michael J Hughes; Bradley L Campbell; William F Belknap; Timothy C Smith; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV WEST BETHESDA MD
|
| TEMPEST is a computational tool that is being developed to predict the seakeeping and dynamic stability performance of a steered ship in large waves. The theory for TEMPEST is being developed in several levels. The difference between the theory levels is in the fidelity and complexity of the environment definition and the component force models. This report describes the Level-0 theory. The objective of the Level-0 version of TEMPEST is ... |
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| Probabilistic Collocation Method for NDE Problems with Uncertain Parameters with Arbitrary Distributions (Preprint) |
Nov 2011 |
10 pages |
| Authors:
Jeremy S Knopp; Mark P Blodgett; M R Cherry; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| In order to quantify the reliability of NDE systems, large amounts of experiments are performed to develop a probability of detection (POD) curve for the system. These POD studies require a substantial amount of experimentation which can sometimes be cost prohibitive. To expedite the process of developing these curves, highly precise numerical models are used in conjunction with NDE sensors to understand the uncertainties associated with the inspections. Numerical models ... |
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| Experimental Eddy Current Measurements of Flawed Edges Compared with Results from Probabilistic Numerical Models (Preprint) |
Nov 2011 |
8 pages |
| Authors:
Matthew Cherry; Jeremy Knopp; Mark Blodgett; Ramana Grandhi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| Eddy current detection of flaws in edges presents challenges in experimental procedures during benchmark studies in the laboratory for model validation as well as practical implementation of a real world detection system. These difficulties result in distortions to the signal that mask the effects from the flawed region itself. Rather than attempting to perfect the experimental setup, we propose to make the numerical models more robust by incorporating randomness in ... |
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| Engineering an Undergarment for Flash/Flame Protection |
Nov 2011 |
10 pages |
| Authors:
Frazier Hull; Jett Gambill; Andrew Hansche; Gian Agni; John Evangelista; Celia Powell; Margaret Auerbach; Joel Dillon; Oezer Arnas; MILITARY ACADEMY WEST POINT NY DEPT OF CIVIL AND MECHANICAL ENGINEERING
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| This paper presents a continuation of projects spanning the last two years. In year one, the physical characteristics and medical effects of burns and Improvised Explosive Device, IED, blasts were investigated. In year two, the possible use of commercial intumescent materials with fabric was studied. The identified needs for research into the effect of undergarments on burn protection are focused in this study. Additionally, Thermal Protective Performance, TPP-(ISO 17492) and ... |
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| Numerical Weather Prediction and Earth System Prediction to Better Understand Sea Level Rise/Coastal Issues as They Affect Readiness |
Nov 2011 |
25 pages |
| Authors:
Dave McCarren; NAVAL METEOROLOGY AND OCEANOGRAPHY COMMAND STENNIS SPACE CENTER MS
|
| The National Unified Operational Prediction Capability (NUOPC) is a joint effort between NOAA and DoD to improve collaboration and accelerate operational numerical weather prediction. The Earth System Prediction Capability (ESPC) expands this collaboration to prediction of the physical earth system, expands required predictive capability to the decadal scale, and expands collaboration to include DOC, DoD, DOE and NASA. Both efforts seek to create partnerships, standardize numerical prediction practices in order ... |
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| Demonstration Study for Reliability Assessment of SHM Systems Incorporating Model-Assisted Probability of Detection Approach (Preprint) |
Nov 2011 |
10 pages |
| Authors:
Eric A Lindgren; Charles F Buynak; Jeremy S Knopp; John C Aldrin; Enrique A Medina; Jose Santiago; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS & MANUFACTURING DIR METALS CERAMICS & NONDESTRUCTIVE EVALUATION DIV/NONDESTRUCTIVE EVALUATION BRANCH
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| This paper presents the results of a demonstration featuring the application of a validation protocol to a vibration-based structural damage sensing system. The results of the full validation study highlight the general protocol feasibility, emphasize the importance of evaluating key application characteristics prior to the POD study, and demonstrate an approach to quantify varying sensor durability on the POD performance. Challenges remain to properly address long time-scale effects with accelerated ... |
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| Tropical-Cyclone Flow Asymmetries Induced by a Uniform Flow Revisited |
Nov 2011 |
17 pages |
| Authors:
Gerald L Thomsen; Roger K Smith; Michael T Montgomery; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF METEOROLOGY
|
| Idealized, convection-permitting, numerical model simulations are carried out to investigate the hypothesized effects of a uniform flow on the intensification, structural evolution, and maximum intensity of a tropical cyclone. The model used is a modified version of the Pennsylvania State University-National Center for Atmospheric Research fifth-generation Mesoscale Model. For the relatively intense vortices studied here, the differences in intensification rate and mature intensity resulting from changes in the background flow ... |
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| Trust, Opinion Diffusion and Radicalization in Social Networks |
Nov 2011 |
6 pages |
| Authors:
Lin Li; Anna Scaglione; Ananthram Swami; Qing Zhao; CALIFORNIA UNIV DAVIS DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Gossiping models have increasingly been applied to study social network phenomena. This paper is specifically concerned with modeling how the opinions of social agents can be radicalized if the agents interact more strongly with neighbors that share their beliefs. In our model, each agent's belief is represented by a vector of probabilities that a given state is true. The agents average their opinions with that of their neighbors over time, ... |
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| The Mediation Formula: A Guide to the Assessment of Causal Pathways in Nonlinear Models |
27 Oct 2011 |
39 pages |
| Authors:
Judea Pearl; CALIFORNIA UNIV LOS ANGELES DEPT OF COMPUTER SCIENCE
|
| Mediation analysis aims to uncover causal pathways along which changes are transmitted from stimulus to response. Recent advances in causal inference have given rise to a general and easy-to-use estimator for assessing the extent to which the effect of one variable on another is mediated by a third, thus setting a causally-sound standard for mediation analysis of empirical data. This estimator, called Mediation Formula, is applicable to nonlinear models with ... |
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| Using Impact Modulation to Identify Loose Bolts on a Satellite |
21 Oct 2011 |
140 pages |
| Authors:
Janette Jaques; Doug Adams; PURDUE UNIV LAFAYETTE IN
|
| This report investigates the use of Impact Modulation (IM) as a means for detecting loose bolts in a satellite structure. First, a two-beam, one-bolt assembly is studied to establish guidelines for implementing IM. Then, theoretical models are developed to provide a basis for applying IM to bolted joints. Two analysis methods for identifying loose bolts within a structure are then proposed. These methods are demonstrated on a three-beam, two-bolt structure; ... |
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| Integrated Guidance and Control of UAVs for Reactive Collision Avoidance |
18 Oct 2011 |
92 pages |
| Authors:
Charu Chawla; Radhakant Padhi; INDIAN INST OF SCIENCE BANGALORE (INDIA)
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| Unmanned aerial vehicles (UAVs) employed in low altitude flights are liable to collide with urban structures. The present work focuses on the reactive obstacle avoidance problem for unaccountable obstacles like urban edifices, poles, etc. Unlike existing literature that mainly proposes avoidance maneuvers using kinematic and point mass models, an innovative Six-Degree of Freedom model based partial integrated guidance and control (PIGC) approach was used. PIGC performs the avoidance maneuver in ... |
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| Further Examination of the Thermodynamic Modification of the Inflow Layer of Tropical Cyclones by Vertical Wind Shear |
15 Oct 2011 |
39 pages |
| Authors:
M Riemer; M T Montgomery; M E Nicholls; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF METEOROLOGY
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| Recent work has developed a new framework for the impact of vertical wind shear on the intensity evolution of tropical cyclones. A focus of this framework is on the frustration of the tropical cyclone's power machine by shear-induced, persistent downdrafts that flush relatively cool and dry (lower equivalent potential temperature, theta(e)) air into the storm's inflow layer. These previous results have been based on idealised numerical experiments for which we ... |
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| Detectability of Delaminations in Solid Rocket Motors with Embedded Stress Sensors |
14 Oct 2011 |
16 pages |
| Authors:
Anhduong Q Le; L Z Sun; Timothy C Miller; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A finite element model is used to investigate the effect of delaminations on the radial stress distribution along the bondline during the cooling process of a solid rocket motor composed of propellant, insulation, and casing. With the assumption of stress sensors evenly distributed along the circumference of the interface between the propellant and insulation, a relationship is established between the debond angle, the number of sensors, and the required sensor ... |
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