| On Stochastic Stability of Regional Ocean Models With Uncertainty in Wind Forcing |
09-Oct-2007 |
17 pages |
| Authors:
L M Ivanov; P C Chu; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
 | A shallow-water model was used to understand model error induced by non-Gaussian wind uncertainty. Although the model was simple, it described a generic system with many degrees of freedom randomized by external noise. The study focused on the nontrivial collective behavior of finite-amplitude perturbations on different scales and their influence on model predictability. The error growth strongly depended on the intensity and degree of spatial inhomogeneity of wind perturbations. For ... |
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| Development of a Mathematica Tool for Implementation of a Prognostics Decision-Making Process Based on Component Life History |
MAR 2006 |
134 pages |
| Authors:
Michael J. Cushing; ARMY MATERIEL SYSTEMS ANALYSIS ACTIVITY ABERDEEN PROVING GROUND MD
|
| The key benefit of prognostics is that it can be used to reduce failure risks during deployments and missions when failure is particularly disadvantageous and maintenance inconvenient due to the reduced logistics footprint One approach to prognostics is to monitor usage in conjunction with an aging model thereby keeping track of remaining component lifetime. This enables one to track usage with on-board sensors and embed an algorithm in on-system logistics ... |
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| Statistical Assessment of NVG Noise |
MAR 2006 |
22 pages |
| Authors:
Jesse G. Wales; Peter L. Marasco; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH HUMAN EFFECTIVENESS DIRECTORATE
|
| New advancements in charged-coupled device (CCD) technology allow for further investigation into the spatial nature of night vision goggle (NVG) noise distributions. This is significant because it is common practice in new NVG technology to combine image intensifiers with CCDs for night vision imaging. In this study, images of NVG noise are recorded by a CCD camera while varying input radiance and using multiple goggle types. Noise distributions characterized using ... |
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| Effect of Ply Thickness on the Damage Development in Composite Laminates (Preprint) |
FEB 2006 |
13 pages |
| Authors:
Ran Y. Kim; Sangwook Sihn; Steven L. Donaldson; DAYTON UNIV RESEARCH INST (UDRI) OH ENERGY AND ENVIRONMENTAL ENGINEERING DIV
|
| This paper describes the experimental investigation on the effect of ply thickness on the first ply failure, delamination, and the subsequent final failure of graphite/epoxy composite laminates. The laminates considered in this paper are a cross-ply and two quasi-isotropic laminates containing thin plies in the desired interface. The onset of the first ply failure and delamination, and the stress-free temperature are experimentally determined. The experimental results for ply crack and ... |
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| Analytic Model Development for Ceramic Gun Tubes |
SEP 2005 |
30 pages |
| Authors:
Robert Carter; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The equations for calculating the probability of failure for an internally pressurized ceramic tube are straightforward and well defined in the literature. The most common solution is for a tube subjected only to an internal pressure. This approach neglects any external pressure, over wrap, or sheathing system that may be used to maintain or promote a beneficial compressive pre-stress. The current research has focused on the development of a model, ... |
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| Effects of Machining on the Uniaxial and Equibiaxial Flexure Strength of CAP3 AD-995 Al2O3 |
SEP 2005 |
70 pages |
| Authors:
Andrew A. Wereszczak; Jeffrey J. Swab; Reuben H. Kraft; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The effect of surface condition on the uniaxial and equibiaxial flexure strength of CoorsTek's CAP3 AD-995 alumina was examined. (Note that this material was found not to be the same as CoorsTek's AD-955 alumina-a comparison and discussion of the differences are provided in this report.) The following four surface conditions were considered: as-fired (i.e., unmachined) surfaces; the condition produced by CoorsTek's standard surface-grinding procedures (i.e., the condition they will provide ... |
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| Size Effects in Ceramic Materials: Computational Issues Associated with Parameter Estimations |
APR 2005 |
36 pages |
| Authors:
Stephen F. Duffy; Eric H. Baker; CONNECTICUT RESERVE TECHNOLOGIES LLC STOW OH
|
| Two test specimen geometries obtained from circumferentially machined, tubular components have been proposed to investigate different flaw populations that might be present in a ceramic gun barrel. C-ring specimens tested in compression will generate maximum tensile stress states at the outer surface of the barrel. This stress state will activate critical flaws that are oriented parallel to the long axis of the tube. The sectored flexure bar specimen tested in ... |
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| Probability Distribution Function of the Upper Equatorial Pacific Current Speeds |
2005 |
19 pages |
| Authors:
Peter C. Chu; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| The probability distribution function (PDF) of the upper (0-50 rn) tropical Pacific current speeds (w), constructed from hourly ADCP data (1990-2007) at six stations for the Tropical Atmosphere Ocean project satisfies the two-parameter Weibull distribution reasonably well with different characteristics between El Nino and La Nina events: In the western Pacific, the PDF of w' has a larger peakedness during the La Nina events than during the El Nino events: ... |
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| Failure Surfaces for the Design of Ceramic-Lined Gun Tubes |
DEC 2004 |
7 pages |
| Authors:
Robert Carter; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| It is desired to incorporate advanced materials in gun barrels to increase service life, enable advanced propellants to provide for increased kinetic energy, and decrease system weight. Ceramic materials possess superior erosion resistance, high temperature performance, and lower density than steel making them attractive candidates as gun tube liners. A new design approach is necessary to address the large variability in strength, one that is probabilistic instead of deterministic in ... |
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| Modeling Dynamic Casualty Mortality Curves in the Tactical Medical Logistics (TML+) Planning Tool |
08 OCT 2004 |
27 pages |
| Authors:
Ray Mitchell; Mike Galarneau; Bill Hancock; Doug Lowe; NAVAL HEALTH RESEARCH CENTER SAN DIEGO CA
|
| Medical simulation models, such as the Naval Health Research Center's (NHRC) Tactical Medical Logistics (TML+) planning tool, stochastically represent the mortality of casualties with life-threatening injuries at various points in the Medical Treatment Facility (MTF) network flow. NHRC is seeking to determine a mathematical (probabilistic) representation of a conditional survival function that is reasonable in the context of other stochastic models being used in TML+. The paper describes NHRC's research ... |
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| Wave Impact Analysis and Results Obtained from a Segmented Model of the High-Speed Sealift Trimaran Model 5594 |
JUN 2004 |
55 pages |
| Authors:
Christina Simone; Thomas F. Brady; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD SURVIVABILITY STRUCTURES AND MATERIALS DIRECTORATE
|
| Hydrodynamic loads testing was completed on a segmented, high-speed sealift (HSS) trimaran model, number 5594, having a scaled ratio 1:45. The model was comprised of six shell sections connected using a calibrated backspline with instrumentation to measure primary and secondary hull girder loading. This test was an evaluation by the Navy of a notional structural design for a lightweight high-speed hull form in support of the High Speed Sealift Program. ... |
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| Mechanical Properties of MEMS Materials |
MAR 2004 |
60 pages |
| Authors:
W. N. Sharpe Jr.; K. J. Hemker; R. L. Edwards; JOHNS HOPKINS UNIV BALTIMORE MD
|
| New techniques and procedures were developed to measure the mechanical properties of the thin-film structural materials used in microelectromechanical systems. Tensile stress-strain curves were measured for polysilicon, silicon nitride, silicon carbide, and electroplated nickel. For example, polysilicon has a Young's modulus of 160 GPa and a Poisson's ratio of 0.22. It is a linear brittle material with fracture strength as high as 3 GPa. The mechanical properties of electroplated nickel ... |
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| Models of Land Clutter vs Grazing Angle, Spatial Distribution and Temporal Distribution - L-Band VV Polarisation Perspective |
MAR 2004 |
|
| Authors:
Yunhan Dong; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION SALISBURY (AUSTRALIA) ELECTRONICS AND SURVEILLANCE RESEARCH
|
 | Land clutter issues and modeling from a perspective of L-band VV polarization are addressed. In particular, clutter distributions in three different dimensions are discussed in detail. First, a three-term model for the dependence of land clutter on grazing angle is proposed. The model is site- specific and landcover-dependent. Parameters for dominant types of landcover in the Northern Territory region are regressed using AirSAR and MCARM measurements as well as others ... |
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| The Application of Fracture Mechanics to Estimate the Crack Length for Developing an Inspection Criterion |
JUN 2003 |
|
| Authors:
C. T. Liu; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| Failure Analysis of Three Si3N4 Balls Used in Hybrid Bearings |
15 FEB 2003 |
29 pages |
| Authors:
M. J. O'Brien; N. Presser; E. Y. Robinson; AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
|
| The rolling-element fatigue life of advanced hybrid material bearings consisting of silicon-nitride balls, REX20 tool-steel inner races, and CRU20 tool-steel outer races was measured under well-qualified laboratory testing. Multiple sets of four bearings (207H size) were tested using the least-of-four technique and sudden-death statistics to obtain a Weibull distribution based upon a bivariate model that accounted for load, time, and sample size. The Weibull distribution model shows that the advanced ... |
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| C-Ring Strength of Advanced Monolithic Ceramics |
2003 |
9 pages |
| Authors:
A. A. Wereszczak; R. J. Caspe; J. J. Swab; S. F. Duffy; E. H. Baker; OAK RIDGE NATIONAL LAB TN METALS AND CERAMICS DIV
|
| Alumina, silicon carbide, silicon nitride, and zirconia are common candidate ceramics for load-bearing tubular components. To help facilitate design and reliability modeling with each ceramic, Weibull strength distributions were determined with each material using a diametrally compressed c-ring specimen in accordance with ASTM C1323. The investigated silicon nitride and zirconia were found to exhibit higher uncensored characteristic strengths than the alumina and silicon carbide. The occurrence of chamber-located fracture initiation ... |
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| Burst Testing of Filament-Wound Graphite-Epoxy Composite Cylindrical Tubes |
01 NOV 2002 |
80 pages |
| Authors:
D. J. Chang; H. A. Katzman; J. P. Nokes; P. M. Adams; S. T. Amimoto; AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
|
| An experimental and analytical program was performed to elucidate the failure process of filament-wound graphite-epoxy tubes, especially the effects of wrinkled fibers and of proof testing on tube burst strength. Four types of tubes were tested: those free of flaws, those with a minor or severe helical wrinkle, and those with a hoop wrinkle. Tests included pressurization to burst, and single or multiple proof tests followed by burst. Data collection ... |
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| Estimating the Initial Crack Size in a Particulate Composite Material: An Analytical and Experimental Approach |
11 OCT 2001 |
17 pages |
| Authors:
C. T. Liu; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| The objectives in this report are to: determine the inherent critical initial crack size in a particulate composite material, determine the statistical distribution function of the inherent critical crack size, normal distribution, two parameter lognormal distribution, two parameter weibull distribution, and second asymptotic distribution of maximum value. |
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| Statistical Characterization of Multibeam Bathymetry Data |
22 MAY 2001 |
18 pages |
| Authors:
Leslie Morgan; Andrew Martinez; Leann Myers; Brian Bourgeois; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| Multibeam sonar systems produce high-density depth data of the ocean floor. Point pattern analysis of the individual depth points is conducted to determine an appropriate parameterized point-to-event distance distribution, F(y). This distribution is needed to quantify the lower bound on the estimated position error of a terrain-based navigation system being developed. The null hypothesis assumes that a Poisson point process produced the two-dimensional pattern. Under the null, F(y) has been ... |
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| Improving Nominal Reliability Confidence Bounds Using Coverage Probabilities Generated Through Monte Carlo Simulation and Illustrated by Military Application |
SEP 2000 |
77 pages |
| Authors:
Jon L. Halverson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Estimating the failure time of a product with a high degree of confidence is a difficult endeavor. Clearly, if the product is inexpensive and fails quickly, extensive tests can be run to make prediction more accurate. When the item under scrutiny is expensive, not prone to failure, or both, calculating accurate estimates and confidence bounds (CBs) becomes more difficult. Furthermore, many methods currently in use are prone ... |
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| Estimation of Extremes from Limited Time Histories: The Routine MaxFits with Wind Turbine Examples |
MAY 2000 |
53 pages |
| Authors:
LeRoy M. Fitzwater; Steven R. Winterstein; STANFORD UNIV CA DEPT OF CIVIL ENGINEERING
|
| This report describes and illustrates the use of the routine MaxFits. This routine estimates statistics of extremes corresponding to arbitrary dynamic load or response processes. It estimates statistics of extremes from limited duration time histories, which may arise either from experimental tests or computationally expensive simulation. A wide range of statistics-e.g., mean, standard deviation, and arbitrary fractiles-can be estimated for an extreme over an arbitrary duration T. The routine also ... |
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| Surface Fatigue Lives of Case-Carburized Gears With an Improved Surface Finish |
APR 2000 |
15 pages |
| Authors:
T. L. Krantz; M. P. Alanou; H. P. Evans; R. W. Snidle; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH GLENN RESEARCH CENTER
|
| Previous research provides qualitative evidence that an improved surface finish can increase the surface fatigue lives of gears. To quantify the influence of surface roughness on life, a set of AISI 9310 steel gears was provided with a near-mirror finish by superfinishing. The effects of the superfinishing on the quality of the gear tooth surfaces were determined using data from metrology, profilometry, and interferometric microscope ... |
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| On Selection Procedures for Exponential Family Distributions Based on Type-I Censored Data |
JAN 2000 |
14 pages |
| Authors:
Shanti S. Gupta; Shuyuan He; Jianjun Li; PURDUE UNIV LAFAYETTE IN DEPT OF STATISTICS
|
| We investigate the problem of selecting the best population from exponential family distributions based on type-I censored data. A Bayes rule is derived and a monotone property of the Bayes selection rule is obtained. Following that property, we propose an early selection rule. Through this early selection rule, one can terminate the experiment on a few populations early and possibly make the final decision before the censoring time. An example ... |
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| Multiple Comparison Pruning of Neural Networks |
SEP 1999 |
88 pages |
| Authors:
Donald E. Duckro; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| Reducing a neural network's complexity improves the ability of the network to be applied to future examples. Like an overfitted regression function, neural networks may miss their target because of the excessive degrees of freedom stored up in unnecessary parameters. Over the past decade, the subject of pruning networks has produced non-statistical algorithms like Skeletonization, Optimal Brain Damage, and Optimal Brain Surgery as methods to remove connections with the least ... |
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| Advancing Reliability, Maintainability, and Availability Analysis Through a Robust Simulation Environment |
02 JUL 1999 |
254 pages |
| Authors:
Stephen Paul Chambal; ARIZONA STATE UNIV TEMPE
|
| The field of reliability has become a dominant factor in industry as companies strive for competitive advantages in the market place. Reliability, maintainability, and availability (RM&A) analysis provides insight into system characteristics and overall behavior, describing parameters such as time between failures, mean down time, and cost estimation. For simple systems, analytical methods can calculate exact solutions. Complex systems, however, require different methods for approximating solutions. Simulation is one solution ... |
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| Estimation and Goodness-of-Fit in the Case of Randomly Censored LifetimeData |
JUN 1999 |
216 pages |
| Authors:
David M. Reineke; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
| A new continuous distribution function estimator for randomly censored data is developed, discussed, and compared to existing estimators. Minimum distance estimation is shown to be effective in estimating Weibull location parameters when random censoring is present. A method of estimating all3 parameters of the 3-parameter Weibull distribution using a combination of minimum distance and maximum likelihood is also given. Cramer-von Mises and Anderson-Darling goodness-of-fit test statistics are modified to measure ... |
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| Prediction of Extreme Responses from Limited Data |
JUN 1999 |
110 pages |
| Authors:
P. R. DE Jong; STANFORD UNIV CA DEPT OF CIVIL ENGINEERING
|
| The main objective of this thesis is to study procedures to estimate statistics of extreme responses to random excitation. Various methods are applied to predict the extreme statistics of the horizontal offset of a spar buoy, consisting of 3 dominant frequency bands; resonant surge, resonant pitch, and wave frequency response. In order to study the effect of limited data, both 1 hour of model test data and 36 hours of ... |
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| Low Grazing Angle Tarrain Backscattering Coefficient Generator |
MAR 1999 |
87 pages |
| Authors:
William N. O'Connor; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
|
| A near-horizon probabilistic terrain backscatter coefficient generator is introduced, combining modified sea-state curves with Weibull-type probability density functions. A total of nine terrain type classifications (soils & rocks, trees, grasses, shrubs, short vegetation, roads, urban areas, dry snow, and wet snow) are supported, for seven radar bands (L, S, C, X, Ku, Ka, and W), and both linear (HH, VV) and cross (HV, VH) polarizations. The Weibull functions are based ... |
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| Analysis of Incomplete Data in Presence of Competing Risks |
DEC 1998 |
25 pages |
| Authors:
Debasis Kundu; Sankarshan Basu; PENNSYLVANIA STATE UNIV UNIVERSITY PARK CENTER FOR MULTIVARIATE ANALYSIS
|
| In medical studies or in reliability analysis an investigator is often interested with the assessment of a specific risk in presence of other risk factors. In the Statistical literature it is known as the analysis of competing risks model. The competing risks model assumes that the data consists of a failure time and an indicator denoting the cause of failure. Several studies have been carried out under this assumption for ... |
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| Reliability Assessment Test (RAT) Program Life Data Analysis Methods |
08 MAY 1998 |
16 pages |
| Authors:
Fredrick Danzy; Jean S. Smathers; NAVAL RESEARCH LAB WASHINGTON DC SPACEAPPLICATIONS BRANCH
|
| Two life data analysis methods, which will be employed in the Global Positioning System Block IIR Rubidium Atomic Frequency Standard Assessment Test Program will be discussed. The analysis methods will provide information regarding the population characteristics. |
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| Towards a Predictive Design Methodology of Composite Laminates and Patches: Physical Models of Environmental and Thermal Sensitive Failure Processes |
APR 98 |
45 pages |
| Authors:
Peter W. Beaumont; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF ENGINEERING
|
| Once damage initiates, the stress distribution at the notch tip is altered by the growth of splits and delaminations and ultimate failure is controlled by the maximum notch tip stress in the load-bearing 0 degree plies, sigma(0p). A damage-based model for notched tensile strength has been assembled, using the results of both finite element analysis and Weibull experiments. Thermal residual stresses are included into the model. Additional energy contributions are ... |
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| Comparing the Maximum Likelihood Method and a Modified Moment Method to Fit a Weibull Distribution to Aircraft Engine Failure Time Data |
SEP 1997 |
|
| Authors:
Fernando Gueimil; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis provides a comparison of the accuracies of two methods for fitting a Weibull distribution to a set of aircraft engines time between failure data. One method used is the Maximum Likelihood Method and assumes that these engine failure times are independent. The other method is a Modified Method of Moments procedure and uses the fact that if time to failure T has a Weibull distribution with scale parameter ... |
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| Uniaxial Strength and Mode I Fracture Toughness of Hot Pressed Silicon Carbide (SiC) Materials |
JUN 97 |
30 pages |
| Authors:
Kyu Cho; R. N. Katz; Isa Bar-On; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Silicon carbide (SiC) ceramics are being used and considered for a number of room temperature wear and optical applications where strength and fracture toughness are critical design parameters. Thus, there is a requirement for high-quality tensile strength and Weibull data for this class of materials. This report will present room temperature uniaxial tensile strength data, single-edge precracked beam (SEPB) fracture toughness (K sub IC) data, and fractographic analysis for several ... |
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| Millimeter-Wave Backscatter Measurements in Support of Surface Navigation Applications |
18 APR 97 |
121 pages |
| Authors:
Brett R. Snuttjer; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| Millimeter wave (MMW) short range radar systems have unique advantages in surface navigation applications, such as military vehicle mobility in inclement conditions, aircraft landing assistance and missile guidance. MMW radars systems have recently become commercially affordable, and are being developed for automobile collision avoidance applications. Two types of radar cross section (RCS) measurements were performed at 95 GHz. Grazing angle clutter data were obtained from common surfaces. The RCS of ... |
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| Photonics Space Time Processing |
APR 97 |
35 pages |
| Authors:
Pierre J. Talbot; ROME LAB ROME NY
|
| Radar clutter is usually characterized statistically by two parameter lognormal or Weibull models. The utilization of two parameter models has been impeded by a lack of methods for estimating the parameters. An optical monopulse chirp processor is presented that performs real-time adaptive estimates of the lognormal and Weibull parameters. The processor architecture requires only mature optical power or heterodyne spectrum analyzer technology. The optical monopulse chirp processor issued as United ... |
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| An Evaluation Procedure for Determining the Adequacy of Alluvial River Sediment Data Sets |
MAR 97 |
204 pages |
| Authors:
William D. Martin; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS COASTAL HYDRAULICS L AB
|
| Well over a century of research into the relationship between sediment and water and the amount of sediment transported under any given set of flow conditions has produced a prolific number of sediment transport relationships. These functions are based on measurable physical, sediment, and hydraulic parameters. By properly selecting one or more of these functions, sediment transport may be predicted for a variety of conditions. Due to the nature of ... |
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| Interval-Censored Data |
DEC 96 |
79 pages |
| Authors:
Ahmed A. Abu-Taleb; M. B. Rao; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
|
| In estimating the lifetime distribution of a product, the following periodic inspection plan is put forward. Select a random sample of n units of the product and set them to work. Choose an integer m > or = 1, numbers 0 |
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| Proceedings of the Annual U.S. Army Conference (1st) on Applied Statistics, Held in Adelphi, Maryland on 18-20 October 1995 |
AUG 96 |
168 pages |
| Authors:
Barry Bodt; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The first U.S. Army Conference on Applied Statistics was held 18-20 October 1995 at the headquarters of the U.S. Army Research Laboratory in Adelphi, MD. The conference was cosponsored by the U.S. Army Research Laboratory, the U.S. Military Academy, the Army Research Office, the Walter Reed Army Institute of Research, the National Institute of Standards and Technology, and the TRADOC Analysis Center-WSMR. Papers given at the conference addressed the development ... |
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| Mechanical Properties of Hot Pressed Titanium Diboride |
AUG 96 |
24 pages |
| Authors:
Kyu Cho; Robert N. Katz; Isa Bar-On; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Room temperature uniaxial and flexural strength, Weibull parameters, and fracture toughness of hot pressed TiB2 are presented. Fracture toughness estimated from fractographic analysis was compared to the Single Edge Precracked Beam (SEPB) K sub (IC) measurements. Discrepancy between the estimated and measured values were rationalized by invoking the possibility of R-curve behavior. Fractographic analysis and the load displacement records of Vickers indented specimens point to the existence of rising R-curve ... |
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| Methods for Determining Performance Expectations and Optimal No Build Times of Fielded Jet Engines |
JUN 96 |
112 pages |
| Authors:
Mark E. Mlikan; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis investigates methods for determining fielded jet engine performance expectations. Data exported from the Naval Aviation Logistics Data Analysis (NALDA) data base was fitted by a Weibull distribution to obtain the engine probability density function, cumulative density function, mean time between failure, failure rate, and condition reliabilities. The thesis applies the results of the data analysis by using a commercial software package, Mathcad, to find the solution to an ... |
|
| Multichannel Signal Processing Extensions |
FEB 96 |
103 pages |
| Authors:
Robert Vienneau; KAMAN SCIENCES CORP UTICA NY
|
| This effort extends the signal processing capabilities of the Multichannel Signal Processing Simulation System (MSPSS), including: - the analysis of a signal detection algorithm for a constant magnitude signal of unknown amplitude in white or colored noise; - the addition of a capability to generate Weibull distributed noise or clutter; - the implementation of the representative model that provides user control over statistical properties of simulated space-time data, as calculated ... |
|
| Covariance Matrix Estimator Performance In Non-Gaussian Spherically Invariant Random Processes. Revision |
JAN 96 |
26 pages |
| Authors:
James H. Michels; ROME LAB ROME NY
|
| This report describes the performance of the covariance matrix estimator in non-Gaussian spherically invariant random processes (SIRP). Analytic expressions are derived for the variance of the estimator. Specific consideration is given to the special cases of Weibull and K-distributed processes as a function of the shape parameter. Validation is achieved via Monte-Carlo simulation. The expressions reveal the increase in the estimator variance for non-Gaussian SIRP's as well as the sample ... |
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| Nonparametric Estimation for a General Repair Model |
JUN 95 |
33 pages |
| Authors:
Crisanto Dorado; Myles Hollander; Jayaram Sethuraman; FLORIDA STATE UNIV TALLAHASSEE DEPT OF STATISTICS
|
| The construction and analysis of repair models is an important area in reliability. A commonly used model is the minimal repair model. Under this model, repair restores the state of the system to its level prior to failure. Kijima introduced repair models that could be classified as "better-than- minimal". Under Kijima's models, the system, upon repair, is functionally the same as a working system of lesser age which has never ... |
|
| Shelf Life Extension for POL Products |
APR 95 |
94 pages |
| Authors:
In-Sik Rhee; Rutkowski; TACOM RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
| Extending the shelf life cycle of petroleum, oil, and lubricant (POL) products is clearly conservation effective for military petroleum and water handling distribution equipment (PWHE) as well as other vehicles and equipment To review shelf life requirements of POL products, a total twenty-three (23) specification products were evaluated using the Maximum Likelihood (ML) method for the Weibull distribution. Data utilized for this study were the results of routine shelf life ... |
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| PDF Approximation for Radar Data |
APR 95 |
47 pages |
| Authors:
Lisa K. Slaski; John E. Maher; ROME LAB GRIFFISS AFB NY
|
| The subject of this report is a new method for approximating the underlying probability density function of random data, called the Osturk Algorithm, and its application to spatial radar clutter data. This algorithm works extremely well with only 100 independent samples.This is an improvement over classical methods which can only determine statistical consistency with a specified distribution and require thousands of independent samples. The efficiency of this algorithm allows the ... |
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| Modified Goodness-Of-Fit Tests For The Inverse Gaussian Distribution With Two Unknown Parameter |
MAR 95 |
339 pages |
| Authors:
Hueseyin Guenes; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| Modified Kolmogorov- Smirnov (KS), Anderson-Darling (AD), Cramer- von Mises (CV), Kupier (V), and Watson (W) goodness-of-fit tests are generated for the inverse Gaussian distribution with unknown parameters. The inverse Gaussian parameters are estimated by maximum likelihood estimation. A Monte Carlo simulation of 50,000 repetitions is used to generate critical values for sample sizes of 5 through 50 with an increment of five, sample sizes of 60 through 100 with an ... |
|
| A New Goodness-of-Fit Test for the Gamma Distribution Based on Sample Spacings from Complete and Censored Samples |
MAR 95 |
168 pages |
| Authors:
Huseyin Duman; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| This thesis studies a new goodness-of-fit test for the gamma distribution with known shape parameter. This test statistic, Z*, is based on spacings from complete or censored samples. The size of samples varied between 5 and 35. The critical value tables were generated for the Z* test statistic for complete and censored samples. The critical values were obtained for five different significance levels: 0.20 0.15, 0.10, 0.05, and 0.01. An ... |
|
| Current Issues Concerning Reliability Estimation in Operational Test and Evaluation |
SEP 94 |
65 pages |
| Authors:
Timothy P. Anderson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| There are several perennial issues concerning rehability estimation in Operational Testing and Evaluation (OT&E). Two of these include, 'how should one model the underlying failure distribution of a continuous-time system,' and, 'how can a testing agency use information from DT in order to reduce OT resource requirements.' In the former issue, some OT&E analysts have questioned whether or not the exponential failure distribution should be used in all cases for ... |
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| Life Prediction Methodology for Composite Laminates. Part 1. Constant Amplitude and Two-Stress Level Fatigue |
SEP 94 |
45 pages |
| Authors:
Jeffery R. Schaff; Barry D. Davidson; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| A strength-based wearout model is presented for predicting the residual strength and life of composite laminates subjected to constant amplitude or two-stress level fatigue loadings. It is assumed that the laminate undergoes proportional loading, that its residual strength is a monotonically decreasing function of the number of loading cycles, and that the probability of failure after an arbitrary number of cycles may be represented by a two parameter Weibull function. ... |
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| Rotating Beam Fatigue Testing and Hybrid Ceramic Bearings |
JUL 94 |
170 pages |
| Authors:
Y. P. Chiu; TORRINGTON CO CT
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| Silicon nitride is the material of choice for ceramic rolling bearings. The issue of low operational reliability in certain rolling contact applications in DoD systems may be related to its limited room temperature bending strength as compared with modern bearing steels. To explore the cyclic fatigue strength of silicon nitride, rotating beam fatigue tests have been performed for two types of high quality bearing-grade HPSN. A total of 122 rotating ... |
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WEIBULL DENSITY FUNCTIONS
