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Air Force Institute of Technology

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Articles 3211 - 3240 of 5700

Full-Text Articles in Engineering

Towards The Development Of A Defensive Cyber Damage And Mission Impact Methodology, Larry W. Fortson Jr. Mar 2007

Towards The Development Of A Defensive Cyber Damage And Mission Impact Methodology, Larry W. Fortson Jr.

Theses and Dissertations

The purpose of this research is to establish a conceptual methodological framework that will facilitate effective cyber damage and mission impact assessment and reporting following a cyber-based information incidents. Joint and service guidance requires mission impact reporting, but current efforts to implement such reporting have proven ineffective. This research seeks to understand the impediments existing in the current implementation and to propose an improved methodology. The research employed a hybrid historical analysis and case study methodology for data collection through extensive literature review, examination of existing case study research and interviews with Air Force members and civilian personnel employed as …

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Indentifying And Assessing Effective Mechanisms For Technology Transfer, Michael A. Romero Mar 2007

Indentifying And Assessing Effective Mechanisms For Technology Transfer, Michael A. Romero

Theses and Dissertations

The ability to shift knowledge and resources from federal laboratories to industrial and academic partners and vice versa is the primary reason that technology transfer (T2) exists today. Without the cooperation of federal, state, and private agencies working together to resolve today’s technology quandaries, a lot of the breakthroughs experienced today would not exist. This research was focused on uncovering which mechanisms are utilized by scientists and engineers. The research entails uncovering both official and unofficial mechanisms and ascertaining why some methods are preferred over others. It is also a secondary focus, to determine which barriers are impeding …

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Quantification Of Risk For Usaf Fire And Emergency Services Flights As A Result Of Shortage In Manpower, Timothy D. Dalby Mar 2007

Quantification Of Risk For Usaf Fire And Emergency Services Flights As A Result Of Shortage In Manpower, Timothy D. Dalby

Theses and Dissertations

The United States Air Force (USAF) is currently experiencing a period of high operations tempo and overseas deployments have become frequent. These deployments will leave home installations short manned. Some amount of risk is incurred by the home installation as a result of the short manning. For an organization, such as an USAF Fire and Emergency Services (FES) flight, whose primary responsibility is the protection of life and property, the incurred risk could be catastrophic. Still no attempt has been made to quantify risk in terms of manpower for the USAF FES flights. The primary purpose of this research was …

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Optimizing The Prioritization Of Natural Disaster Recovery Projects, Jason M. Aftanas Mar 2007

Optimizing The Prioritization Of Natural Disaster Recovery Projects, Jason M. Aftanas

Theses and Dissertations

Prioritizing reconstruction projects to recover a base from a natural disaster is a complicated and arduous process that involves all levels of leadership. The project prioritization phase of base recovery has a direct affect on the allocation of funding, the utilization of human resources, the obligation of projects, and the overall speed and efficiency of the recovery process. The focus of this research is the development of an objective and repeatable process for optimizing the project prioritization phase of the recovery effort. This work will focus on promoting objectivity in the project prioritizing process, improving the communication of the overall …

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The Chaos Of Katrina: A Nonlinear Analysis Of Federal Logistics Support During Hurricane Katrina Relief Operations, Gerald W. Morris Jr. Mar 2007

The Chaos Of Katrina: A Nonlinear Analysis Of Federal Logistics Support During Hurricane Katrina Relief Operations, Gerald W. Morris Jr.

Theses and Dissertations

This thesis presents a case study of federal logistics support during Hurricane Katrina disaster relief operations. Data from federal contracts covering the first 10 weeks of Katrina are used to measure federal logistics activity. The study investigates whether chaos theory, part of complexity science, can extract information from Katrina contracting data to help managers make better logistics decisions during disaster relief operations. The study uses three analytical techniques: embedding, fitting the data to a logistic equation, and plotting the limit-cycle. Embedding and fitting a logistic equation to the data were used to test for deterministic chaos. The logistic equation and …

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Determining Logistics Ground Support Manpower Requirements For A Reusable Military Launch Vehicle, Sydney C. Michalski Mar 2007

Determining Logistics Ground Support Manpower Requirements For A Reusable Military Launch Vehicle, Sydney C. Michalski

Theses and Dissertations

Successful space-based technologies like satellite imagery and GPS have increased military demand for a rapid-response launch capability. AF Space Command's Operationally Responsive Spacelift program was developed to ensure that the AF has the capability to launch a payload into orbit within hours of a tasking notification, and requires development of a new space launch vehicle. The Reusable Military Launch Vehicle (RMLV) is currently in the design phase. The AF Research Laboratory sponsored development of the MILEPOST simulation model in order to assess the turnaround time, and thus responsiveness, of various design alternatives. The focus of this thesis is to improve …

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An Analysis Of Robust Workforce Scheduling Models For A Nurse Rostering Problem, Paul K. Tower Mar 2007

An Analysis Of Robust Workforce Scheduling Models For A Nurse Rostering Problem, Paul K. Tower

Theses and Dissertations

Disruptions impacting workforce schedules can be costly. A 1999 study of the United Kingdom's National Health Service estimated that as much as 4% of the total resources spent on staffing were lost to schedule disruptions like absenteeism. Although disruptions can not be eliminated, workforce schedules can be improved to be more responsive to disruptions. One key area of study that has expanded over the past few years is the application of traditional scheduling techniques to re-rostering problems. These efforts have provided methods for responding to schedule disruptions, but typically require deviations to the disrupted schedule. This thesis examines five workforce …

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Modeling, Simulation, And Estimation Of Optical Turbulence, Byron P. Formwalt Mar 2007

Modeling, Simulation, And Estimation Of Optical Turbulence, Byron P. Formwalt

Theses and Dissertations

This dissertation documents three new contributions to simulation and modeling of optical turbulence. The first contribution is the formalization, optimization, and validation of a modeling technique called successively conditioned rendering (SCR). The SCR technique is empirically validated by comparing the statistical error of random phase screens generated with the technique. The second contribution is the derivation of the covariance delineation theorem, which provides theoretical bounds on the error associated with SCR. It is shown empirically that the theoretical bound may be used to predict relative algorithm performance. Therefore, the covariance delineation theorem is a powerful tool for optimizing SCR algorithms. …

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Critical Infrastructure Rebuild Prioritization Using Simulation Optimization, Namsuk Cho Mar 2007

Critical Infrastructure Rebuild Prioritization Using Simulation Optimization, Namsuk Cho

Theses and Dissertations

This thesis examines the importance of a critical infrastructure rebuild strategy following a terrorist attack or natural disaster such as Hurricane Katrina. Critical infrastructures are very complex and dependent systems in which their re-establishment is an essential part of the rebuilding process. A rebuild simulation model consisting of three layers (physical, information, and spatial) captures the dependency between the six critical infrastructures modeled. We employ a simulation optimization approach to evaluate rebuild prioritization combinations with a goal of minimizing the time needed to achieve an acceptable rebuild level. We use a simulated annealing heuristic as an optimization technique that works …

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Improved Hyperspectral Image Testing Using Synthetic Imagery And Factorial Designed Experiments, Joseph P. Bellucci Mar 2007

Improved Hyperspectral Image Testing Using Synthetic Imagery And Factorial Designed Experiments, Joseph P. Bellucci

Theses and Dissertations

The goal of any remote sensing system is to gather data about the geography it is imaging. In order to gain knowledge of the earth's landscape, post-processing algorithms are developed to extract information from the collected data. The algorithms can be intended to classify the various ground covers in a scene, identify specific targets of interest, or detect anomalies in an image. After the design of an algorithm comes the difficult task of testing and evaluating its performance. Traditionally, algorithms are tested using sets of extensively ground truthed test images. However, the lack of well characterized test data sets and …

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Prioritizing Satellite Payload Selection Via Optimization, Benjamin S. Kallemyn Mar 2007

Prioritizing Satellite Payload Selection Via Optimization, Benjamin S. Kallemyn

Theses and Dissertations

This thesis develops optimization models for prioritizing payloads for inclusion on satellite buses with volume, power, weight and budget constraints. The first model considers a single satellite launch for which the budget is uncertain and constellation requirements are not considered. Subsequently, we include constellation requirements and provide a more enhanced model. Both single-launch models provide a prioritized list of payloads to include on the launch before the budget is realized. The single-launch models are subsequently extended to a sequence of multiple launches in two cases, both of which incorporate an explicit dependence on the constellation composition at each launch epoch. …

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Approximate Analysis Of An Unreliable M/M/2 Retrial Queue, Brian P. Crawford Mar 2007

Approximate Analysis Of An Unreliable M/M/2 Retrial Queue, Brian P. Crawford

Theses and Dissertations

This thesis considers the performance evaluation of an M/M/2 retrial queue for which both servers are subject to active and idle breakdowns. Customers may abandon service requests if they are blocked from service upon arrival, or if their service is interrupted by a server failure. Customers choosing to remain in the system enter a retrial orbit for a random amount of time before attempting to re-access an available server. We assume that each server has its own dedicated repair person, and repairs begin immediately following a failure. Interfailure times, repair times and times between retrials are exponentially distributed, and all …

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Patterns Of War Termination: A Statistical Approach, Paul D. Robinson Ii Mar 2007

Patterns Of War Termination: A Statistical Approach, Paul D. Robinson Ii

Theses and Dissertations

This research uses an advanced statistical technique to expand upon the current understanding of war termination. Specifically, this thesis addressed questions concerning the most relevant factors toward predicting both the outcomes of interstate wars and the winners of intrastate and extra-systemic wars, within the limitations of the available data. Open-source war data from the Correlates of War Project was analyzed using both binary and multinomial logistic regression techniques. While the Correlates of War Project did not necessarily focus its data collection efforts on those variables historically associated with war termination, it did provide a sufficient number of variables with which …

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Mathematical Programming Model For Fighter Training Squadron Pilot Scheduling, Thomas M. Newlon Mar 2007

Mathematical Programming Model For Fighter Training Squadron Pilot Scheduling, Thomas M. Newlon

Theses and Dissertations

The United States Air Force fighter training squadrons build weekly schedules using a long and tedious process. Very little of this process is automated and optimality of any kind is nearly impossible. Schedules are built to a feasible condition only to be changed with consideration of Wing level requirements. Weekly flying schedules are restricted by requirements for crew rest, days since a pilot's last sortie, sorties in the last 30 days, and sorties in the last 90 days. By providing a scheduling model to the pilot charged with creating the schedule, valuable pilot hours could be spent in the cockpit, …

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Change-Point Methods For Overdispersed Count Data, Brian A. Wilken Mar 2007

Change-Point Methods For Overdispersed Count Data, Brian A. Wilken

Theses and Dissertations

A control chart is often used to detect a change in a process. Following a control chart signal, knowledge of the time and magnitude of the change would simplify the search for and identification of the assignable cause. In this research, emphasis is placed on count processes where overdispersion has occurred. Overdispersion is common in practice and occurs when the observed variance is larger than the theoretical variance of the assumed model. Although the Poisson model is often used to model count data, the two-parameter gamma-Poisson mixture parameterization of the negative binomial distribution is often a more adequate model for …

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Automatic Target Recognition User Interface Tool, David A. Kerns Mar 2007

Automatic Target Recognition User Interface Tool, David A. Kerns

Theses and Dissertations

A computer tool to aid in selecting the best Automatic Target Recognition (ATR) algorithm is developed. The program considers many quantifiers, accepts user-defined parameters, allows for changes in the operational environment and presents results in a meaningful way. It is written for Microsoft Excel. An ATR algorithm assigns a class label to a recognized target. General designations can include "Friend" and "Foe." The error of designating "Friend" as "Foe" as well as "Foe" as "Friend" comes with a high cost. Studying each algorithm's error can minimize this cost. Receiver Operating Characteristic (ROC) curves provide only information on the probabilities given …

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Examining Clandestine Social Networks For The Presence Of Non-Random Structure, Joshua S. Seder Mar 2007

Examining Clandestine Social Networks For The Presence Of Non-Random Structure, Joshua S. Seder

Theses and Dissertations

This thesis develops a tractable, statistically sound hypothesis testing framework for the detection, characterization, and estimation of non-random structure in clandestine social networks. Network structure is studied via an observed adjacency matrix, which is assumed to be subject to sampling variability. The vertex set of the network is partitioned into k mutually exclusive and collectively exhaustive subsets, based on available exogenous nodal attribute information. The proposed hypothesis testing framework is employed to statistically quantify a given partition's relativity in explaining the variability in the observed adjacency matrix relative to what can be explained by chance. As a result, valuable insight …

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A Future-Based Risk Assessment For The Survivability Of Long Range Strike Systems, William D. Heuck Jr. Mar 2007

A Future-Based Risk Assessment For The Survivability Of Long Range Strike Systems, William D. Heuck Jr.

Theses and Dissertations

The United States Air Force today faces the challenge of allocating development resources to prepare for future force projection requirements. In particular, the Air Force's core competency of Global Attack implies a future capability that can quickly and successfully deliver combat effects anywhere in the world with impunity. Understanding that the future threat environment is dynamic and that continued advancements by adversaries will likely degrade the technical superiority of today's weapon systems, the need arises for a planning model to direct development funding to areas with the greatest probability of successfully defending the strike vehicle of 2035. Examining this problem …

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Nonlinear Time-Variant Response In An Avalanche Photodiode Array Based Laser Detection And Ranging System, Michael D. Seal Mar 2007

Nonlinear Time-Variant Response In An Avalanche Photodiode Array Based Laser Detection And Ranging System, Michael D. Seal

Theses and Dissertations

This research effort identifies and models the nonlinear time-variant behavior exhibited by an avalanche photodiode (APD) array based Laser Ranging and Detection (LADAR) system. Based on the original Linear Time-Invariant (LTI) model, the evolution of error in the LADAR signal is examined sequentially from the outgoing pulse through signal digitization. This error evolution shows that the LTI model does not contain a mechanism for causing the observed signal deviations or the failure to meet the Cramer-Rao lower bound for range accuracy. A nonlinear time-variant model is developed based on the interactions of the avalanche photodiodes in the array with the …

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Passive Geolocation Of Low Power Emitters In Urban Environments Using Tdoa, Myrna B. Montminy Mar 2007

Passive Geolocation Of Low Power Emitters In Urban Environments Using Tdoa, Myrna B. Montminy

Theses and Dissertations

Low-power devices are commonly used by the enemy to control Improvised Explosive Devices (IEDs), and as communications nodes for command and control. Quickly locating the source of these signals is difficult, especially in an urban environment where buildings and towers can cause interference. This research presents a geolocation system that combines several geolocation and error mitigation methods to locate an emitter in an urban environment. The proposed geolocation system uses a Time Difference of Arrival (TDOA) technique to estimate the location of the emitter of interest. Using sensors at known locations, TDOA estimates are obtained by cross-correlating the signal received …

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Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey Mar 2007

Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey

Theses and Dissertations

An extended Kalman filter is used to estimate size and packet arrival rate of network queues. These estimates are used by a LQG steady state linear perturbation PI controller to regulate queue size within a computer network. This paper presents the derivation of the transient queue behavior for a system with Poisson traffic and exponential service times. This result is then validated for ideal traffic using a network simulated in OPNET. A more complex OPNET model is then used to test the adequacy of the transient queue size model when non-Poisson traffic is combined. The extended Kalman filter theory is …

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Effects Of Prior Aging At Elevated Temperature In Air And In Argon Environments On Creep Response Of Pmr-15 Neat Resin, Joseph L. Broeckert Mar 2007

Effects Of Prior Aging At Elevated Temperature In Air And In Argon Environments On Creep Response Of Pmr-15 Neat Resin, Joseph L. Broeckert

Theses and Dissertations

Creep behavior of PMR-15 neat resin, a polyimide thermoset polymer, aged in air or argon gaseous environments at 288 °C for up to 1000 h was evaluated. Creep tests were performed at 288 C at creep stress levels of 20 and 10 MPa. Creep periods of at least 25 h in duration were followed by recovery at zero stress. Weight loss and growth of the oxidation layer were also monitored and correlated with aging time. The aging time in both air and argon environments had a strong influence on the creep and recovery response of PMR-15 neat resin. Samples aged …

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Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington Dec 2006

Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington

Theses and Dissertations

This research outlines the development and simulation of a signal processing approach to real time wavefront curvature sensing in adaptive optics. The signal processing approach combines vectorized Charge Coupled Device (CCD) read out with a wavefront modal estimation technique. The wavefront sensing algorithm analyzes vector projections of image intensity data to provide an estimate of the wavefront phase as a combination of several low order Zernike polynomial modes. This wavefront sensor design expands on an existing idea for vector based tilt sensing by providing the ability to compensate for additional modes. Under the proposed wavefront sensing approach, the physical wavefront …

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Reconstructing Spectral Scenes Using Statistical Estimation To Enhance Space Situational Awareness, Travis F. Blake Dec 2006

Reconstructing Spectral Scenes Using Statistical Estimation To Enhance Space Situational Awareness, Travis F. Blake

Theses and Dissertations

A new sensor, the Advanced Electro-Optical System (AEOS) Spectral Imaging Sensor (ASIS) has been developed at the Maui Space Surveillance Complex (MSSC). ASIS is capable of collecting resolved imagery of space objects in 10's-100's of spectral bands while using an adaptive optics system. However, the stringent requirements of collecting ground-based images requires a sensor that induces spectral blurring. Post-processing algorithms to remove this blurring are required to fully exploit these spectral images. This research focuses on developing the reconstruction algorithms, based on proven estimation theories, required to spectrally deblur the images collected from ASIS. Additionally, the research will expand the …

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Branch Detonation Of A Pulse Detonation Engine With Flash Vaporized Jp-8, John David Slack Dec 2006

Branch Detonation Of A Pulse Detonation Engine With Flash Vaporized Jp-8, John David Slack

Theses and Dissertations

Pulse Detonation Engines (PDE) operating on liquid hydrocarbon fuels are limited to operating frequencies of 35 Hz due to long ignition times from a low energy ignition sources. This study shows ignition time of JP-8 can be nearly eliminated by igniting a thrust tube using a secondary detonation. A counter flow heat exchanger attached to a thrust tube utilized waste heat from the detonation process to heat JP-8 to supercritical conditions. The fuel flash vaporized when injected into the air stream of the engine. A detonation was produced by a spark in a 5 cm diameter, 1.37 m long tube. …

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Robust Estimation Of Mahalanobis Distance In Hyperspectral Images, Eduardo C. Meidunas Dec 2006

Robust Estimation Of Mahalanobis Distance In Hyperspectral Images, Eduardo C. Meidunas

Theses and Dissertations

This dissertation develops new estimation methods that fit Johnson distributions and generalized Pareto distributions to hyperspectral Mahalanobis distances. The Johnson distribution fit is optimized using a new method which monitors the second derivative behavior of exceedance probability to mitigate potential outlier effects. This univariate distribution is then used to derive an elliptically contoured multivariate density model for the pixel data. The generalized Pareto distribution models are optimized by a new two-pass method that estimates the tail-index parameter. This method minimizes the mean squared fitting error by correcting parameter values using data distance information from an initial pass. A unique method …

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Vacuum Chamber Construction And Contamination Study Of A Micro Pulsed Plasma Thruster, Jacob H. Debevec Dec 2006

Vacuum Chamber Construction And Contamination Study Of A Micro Pulsed Plasma Thruster, Jacob H. Debevec

Theses and Dissertations

The micro pulsed plasma thruster (micro-PPT) is a simple and versatile electric thruster capable of performing multiple missions, from precise attitude control on standard satellites to primary propulsion for nanosatellites. In order to fill this role as both industry and government move toward utilizing smaller satellites, micro-PPTs first need to be thoroughly tested on the ground. This study examines the deposition profile and rate of particle emission from the thruster so that satellite designers understand any potential contamination issues with sensitive instruments and solar panels. Employing a newly assembled vacuum chamber system, four tests were completed with the micro-PPTs, and …

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Integrated Conceptual Design Of Joined-Wing Sensor Craft Using Response Surface Models, Josh E. Dittmar Dec 2006

Integrated Conceptual Design Of Joined-Wing Sensor Craft Using Response Surface Models, Josh E. Dittmar

Theses and Dissertations

A multidisciplinary conceptual design and analysis of Boeing's joined-wing SensorCraft has been conducted. This analysis was completed using geometrical optimization, aerodynamic analyses, and response surface methodology on a composite structural model. Phoenix Integration's Model Center was used to integrate the sizing and analysis codes found in Raymer's text, "Aircraft Design: A Conceptual Approach" as well as those from the NASA derived conceptual design tool AirCraft Synthesis (ACSYNT), and a modified Boeing Finite Element Model (FEM). This research demonstrated the utility of integrated low-order models for fast and inexpensive conceptual modeling of unconventional aircraft designs.

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An Exploration Of Several Structural Measurement Techniques For Usage With Functionally Graded Materials, Robert A. Reuter Dec 2006

An Exploration Of Several Structural Measurement Techniques For Usage With Functionally Graded Materials, Robert A. Reuter

Theses and Dissertations

Titanium / titanium boride functionally graded 6"x 1"x1" beams were subjected to a four-point beam test in order to critique the value of several measurement techniques. Also, finite element analysis results were compared with experimental values and general observations about the experiment were recorded. Uniform 85% TiB /15% Ti and uniform commercially pure titanium specimens were also subjected to the same loading conditions as a control. Techniques used include digital image correlation, fiber optic strain gauging, strain gauging, and differential infrared thermography techniques. The strain data results were compared with one another and to linear finite element models. It was …

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An M/M/1 Retrial Queue With Unreliable Server, Nathan P. Sherman, Jeffrey P. Kharoufeh Nov 2006

An M/M/1 Retrial Queue With Unreliable Server, Nathan P. Sherman, Jeffrey P. Kharoufeh

Faculty Publications

We analyze an unreliable M/M/1 retrial queue with infinite-capacity orbit and normal queue. Retrial customers do not rejoin the normal queue but repeatedly attempt to access the server at i.i.d. intervals until it is found functioning and idle. We provide stability conditions as well as several stochastic decomposability results.

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