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Title: PARAMETER ESTIMATION IN LINEAR REGRESSION.
Creator: Ollikainen, Kati, Malone, Linda, University of Central Florida
Abstract / Description: Today increasing amounts of data are available for analysis purposes and often times for resource allocation. One method for analysis is linear regression which utilizes the least squares estimation technique to estimate a model's parameters. This research investigated, from a user's perspective, the ability of linear regression to estimate the parameters' confidence intervals at the usual 95% level for medium sized data sets. A controlled environment using simulation with known...
Show moreToday increasing amounts of data are available for analysis purposes and often times for resource allocation. One method for analysis is linear regression which utilizes the least squares estimation technique to estimate a model's parameters. This research investigated, from a user's perspective, the ability of linear regression to estimate the parameters' confidence intervals at the usual 95% level for medium sized data sets. A controlled environment using simulation with known data characteristics (clean data, bias and or multicollinearity present) was used to show underlying problems exist with confidence intervals not including the true parameter (even though the variable was selected). The Elder/Pregibon rule was used for variable selection. A comparison of the bootstrap Percentile and BCa confidence interval was made as well as an investigation of adjustments to the usual 95% confidence intervals based on the Bonferroni and Scheffe multiple comparison principles. The results show that linear regression has problems in capturing the true parameters in the confidence intervals for the sample sizes considered, the bootstrap intervals perform no better than linear regression, and the Scheffe method is too wide for any application considered. The Bonferroni adjustment is recommended for larger sample sizes and when the t-value for a selected variable is about 3.35 or higher. For smaller sample sizes all methods show problems with type II errors resulting from confidence intervals being too wide.
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Date Issued: 2006
Identifier: CFE0001482, ucf:47081
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001482

Title: PREDICTION AND ALLOCATION OF LIVE TO VIRTUAL COMMUNICATION BRIDGING RESOURCES.
Creator: lackey, stephanie, Malone, Linda, University of Central Florida
Abstract / Description: This document summarizes a research effort focused on improving live-to-virtual (L-V) communication systems. The purpose of this work is to address a significant challenge facing the tactical communications training community through the development of the Live-to-Virtual Relay Radio Prediction Algorithm and implementation of the algorithm into an Integrated Live-to-Virtual Communications Server prototype device. The motivation for the work and the challenges of integrating live and virtual...
Show moreThis document summarizes a research effort focused on improving live-to-virtual (L-V) communication systems. The purpose of this work is to address a significant challenge facing the tactical communications training community through the development of the Live-to-Virtual Relay Radio Prediction Algorithm and implementation of the algorithm into an Integrated Live-to-Virtual Communications Server prototype device. The motivation for the work and the challenges of integrating live and virtual communications are presented. Details surrounding the formulation of the prediction algorithm and a description of the prototype system, hardware, and software architectures are shared. Experimental results from discrete event simulation analysis and prototype functionality testing accompany recommendations for future investigation. If the methods and technologies summarized are implemented, an estimated equipment savings of 25%-53% and an estimated cost savings of $150,000.00 - $630,000.00 per site are anticipated. Thus, a solution to a critical tactical communications training problem is presented through the research discussed.
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Date Issued: 2006
Identifier: CFE0001401, ucf:47072
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001401

Title: QUANTITATIVE ASSESSMENT OF SOFTWARE DEVELOPMENT PROJECT MANAGEMENT ISSUES USING PROCESS SIMULATION WITH SYSTEM DYNAMICS ELEMENTS.
Creator: Mizell, Carolyn, Malone, Linda, University of Central Florida
Abstract / Description: The complexity of software development projects makes estimation and management very difficult. There is a need for improved cost estimation methods and new models of lifecycle processes other than the common waterfall process. This work has developed a new simulation model of the spiral development lifecycle as well as an approach for using simulation for cost and schedule estimation. The goal is to provide a tool that can analyze the effects of a spiral development process as well as a tool...
Show moreThe complexity of software development projects makes estimation and management very difficult. There is a need for improved cost estimation methods and new models of lifecycle processes other than the common waterfall process. This work has developed a new simulation model of the spiral development lifecycle as well as an approach for using simulation for cost and schedule estimation. The goal is to provide a tool that can analyze the effects of a spiral development process as well as a tool that illustrates the difficulties management faces in forecasting budgets at the beginning of a project which may encourage more realistic approaches to budgetary planning. A new discrete event process model of the incremental spiral development lifecycle approach was developed in order to analyze the effects this development approach has on the estimation process as well as cost and schedule for a project. The input data for the key variables of size, productivity, and defect injection rates in the model was based on analysis of Software Engineering Laboratory data and provided for analysis of the effects of uncertainty in early project estimates. The benefits of combining a separate system dynamics model with a discrete event process models was demonstrated as was the effects of turnover on the cost and schedule for a project. This work includes a major case study of a cancelled NASA software development project that experienced cost and schedule problems throughout its history. Analysis was performed using stochastic simulation with derived probability distributions for key software development factors. A system dynamics model of human resource issues was also combined with the process model to more thoroughly analyze the effects of turnover on a project. This research has demonstrated the benefits of using a simulation model when estimating to allow for more realistic budget and schedule determination including an interval estimate to help focus on the uncertainty of early estimates.
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Date Issued: 2006
Identifier: CFE0001209, ucf:46939
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001209

Title: USING SURROGATE MEASURES TO PREDICT PATIENT SATISFACTION IN THE EMERGENCY DEPARTMENT.
Creator: Egri, Erica, Malone, Linda, University of Central Florida
Abstract / Description: With healthcare organizations struggling to remain competitive and financially stable in a market where minimizing costs is a priority, hospital administrators feel the sense of urgency when it comes to keeping patients satisfied with services in order to expand volume and market share. The Emergency Department is considered the front door of a healthcare organization, and keeping its visitors satisfied in order to guarantee a future visit or a referral to a friend or family member is a must....
Show moreWith healthcare organizations struggling to remain competitive and financially stable in a market where minimizing costs is a priority, hospital administrators feel the sense of urgency when it comes to keeping patients satisfied with services in order to expand volume and market share. The Emergency Department is considered the front door of a healthcare organization, and keeping its visitors satisfied in order to guarantee a future visit or a referral to a friend or family member is a must. While patient input on the services received in a healthcare facility is essential to improving quality of care, the costs associated with measuring, collecting and analyzing their feedback are remarkable. This research focuses on developing a linear regression model to predict patient satisfaction in the ED using surrogate measures related to patient's socio-demographic characteristics and visit characteristics. With a model of this kind, healthcare administrators can potentially eliminate survey costs while still being able to determine where the hospital stands in the eyes of the patient. Three modeling approaches were used to develop a multiple regression equation. Modeling approach 1 used monthly patient satisfaction scores as the dependent variable collected by a third-party survey organization. The goal of this model was to predict monthly patient satisfaction scores. Modeling approach 2 used patient satisfaction scores collected by the discharge registrar prior to the patient leaving the ED. The goal of this model was to predict patient satisfaction scores on a patient-by-patient basis. Modeling approach 3 used patient satisfaction scores collected by a third-party survey organization. The goal of this modeling approach was to predict patient satisfaction scores on a patient-by-patient basis. Each modeling approach developed in this study used its own survey tool. Though this study had limitations when it came to developing the models and validating the findings, results are very promising. Analysis shows that predicting average patient satisfaction scores on a monthly basis gives the most accurate results, with socio-demographic characteristics and visit characteristics explaining 96% of variation in monthly average patient satisfaction scores. Other model indicators, such as normality of residuals, predicted error, mean square error, and predicted R-square show that the model fits the data very well and has strong predictive ability. Models that attempted to predict patient satisfaction on a patient-by-patient basis appeared to be ineffective, with very large predicted errors and prediction intervals and low predictive ability.
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Date Issued: 2007
Identifier: CFE0001657, ucf:47241
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001657

Title: PRESENCE-DEPENDENT PERFORMANCE DIFFERENCES BETWEEN VIRTUAL SIMULATIONS AND MINIATURE WORLDS.
Creator: Huthmann, Andre, Malone, Linda, University of Central Florida
Abstract / Description: The purpose of simulation is to avoid reality-based constraints by the implemen-tation of a synthetic model. Based on this advantage, interactive simulations have conquered all areas of applications from acquisition, and training, to research. Simulation results are transferred in many ways into reality and conclusions are drawn from the simulation to the application. Many anecdotal observations on human-in-the-loop simulations have shown a significant difference in actor behavior between...
Show moreThe purpose of simulation is to avoid reality-based constraints by the implemen-tation of a synthetic model. Based on this advantage, interactive simulations have conquered all areas of applications from acquisition, and training, to research. Simulation results are transferred in many ways into reality and conclusions are drawn from the simulation to the application. Many anecdotal observations on human-in-the-loop simulations have shown a significant difference in actor behavior between simulations and reality-based applications. It seems that the factors that makes simulation so attractive, namely the absence of constraints and especially of imminent danger for persons and equipment, influence the behavior and thereby the performance of the user. These differences between simulation and reality may lead to false conclusions based on simulation results. The concept of perceiving a simulation as real and of being in the simulation is called sense of presence. This psychological construct can also be described as level of disbelief towards the simulation. Hence, differences in behavior are based on such users assessment of a simulation and subsequently are supposed to be mediated by a difference in presence. This research established significant differences in presence and performance between a simulation and a miniature-world teleoperation task. Presence and performance changed in identical tasks due to the application type and the connected danger to the robot. Also, the results supported a negative relationship between presence and performance: presence increased in the miniature-world and affected performance so that performance decreased. The causal relationship of application type presence performance was established and demands the examination of simulation based results with respect to the perceived danger to equipment, before they are transferred into the real application.
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Date Issued: 2009
Identifier: CFE0002562, ucf:47666
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002562

Title: NONPARAMETRIC MULTIVARIATE STATISTICAL PROCESS CONTROL USING PRINCIPAL COMPONENT ANALYSIS AND SIMPLICIAL DEPTH.
Creator: Beltran, Luis, Malone, Linda, University of Central Florida
Abstract / Description: Although there has been progress in the area of Multivariate Statistical Process Control (MSPC), there are numerous limitations as well as unanswered questions with the current techniques. MSPC charts plotting Hotelling's T2 require the normality assumption for the joint distribution among the process variables, which is not feasible in many industrial settings, hence the motivation to investigate nonparametric techniques for multivariate data in quality control. In this research, the goal...
Show moreAlthough there has been progress in the area of Multivariate Statistical Process Control (MSPC), there are numerous limitations as well as unanswered questions with the current techniques. MSPC charts plotting Hotelling's T2 require the normality assumption for the joint distribution among the process variables, which is not feasible in many industrial settings, hence the motivation to investigate nonparametric techniques for multivariate data in quality control. In this research, the goal will be to create a systematic distribution-free approach by extending current developments and focusing on the dimensionality reduction using Principal Component Analysis. The proposed technique is different from current approaches given that it creates a nonparametric control chart using robust simplicial depth ranks of the first and last set of principal components to improve signal detection in multivariate quality control with no distributional assumptions. The proposed technique has the advantages of ease of use and robustness in MSPC for monitoring variability and correlation shifts. By making the approach simple to use in an industrial setting, the probability of adoption is enhanced. Improved MSPC can result in a cost savings and improved quality.
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Date Issued: 2006
Identifier: CFE0001065, ucf:46792
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001065

Title: IDENTIFICATION OF SYSTEM DESIGN FEATURES THAT AFFECT SICKNESS IN VIRTUAL ENVIRONMENTS.
Creator: Drexler, Julie, Malone, Linda, University of Central Florida
Abstract / Description: The terms "simulator" and "VR" are typically used to refer to specific types of virtual environments (VEs) which differ in the technology used to display the simulated environment. While simulators and VR devices may offer advantages such as low cost training, numerous studies on the effects to humans of exposure to different VEs indicate that motion sickness-like symptoms are often produced during or after exposure to the simulated environment. These deleterious side effects have the...
Show moreThe terms "simulator" and "VR" are typically used to refer to specific types of virtual environments (VEs) which differ in the technology used to display the simulated environment. While simulators and VR devices may offer advantages such as low cost training, numerous studies on the effects to humans of exposure to different VEs indicate that motion sickness-like symptoms are often produced during or after exposure to the simulated environment. These deleterious side effects have the potential to limit the utilization of VE systems if they jeopardize the health and/or safety of the user and create liability issues for the manufacturer. The most widely used method for assessing the adverse symptoms of VE exposure is the Simulator Sickness Questionnaire (SSQ). The method of scoring the symptoms reported by VE users permits the different sickness symptoms to be clustered into three general types of effects or subscales and the distribution or pattern of the three SSQ subscales provides a profile for a given VE device. In the current research, several different statistical analyses were conducted on the SSQ data obtained from 21 different simulator studies and 16 different VR studies in order to identify an underlying symptom structure (i.e., SSQ profile) or severity difference for various types of VE systems. The results of the research showed statistically significant differences in the SSQ profiles and the overall severity of sickness between simulator and VR systems, which provide evidence that simulator sickness and VR sickness represent distinct forms of motion sickness. Analyses on three types of simulators (i.e., Fixed- and Rotary-Wing flight simulators and Driving simulators) also found significant differences in the sickness profiles as well as the overall severity of sickness within different types of simulator systems. Analyses on three types of VR systems (i.e., HMD, BOOM, and CAVE) revealed that BOOM and CAVE systems have similar sickness profiles, which are different than the HMD system profile. Moreover, the results showed that the overall severity of sickness was greater in HMD systems than in BOOM and CAVE systems. Recommendations for future research included additional psychophysical studies to evaluate the relationship between various engineering characteristics of VE systems and the specific types of sickness symptoms that are produced from exposure to them.
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Date Issued: 2006
Identifier: CFE0000989, ucf:46700
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000989

Title: DIRECT MANIPULATION OF VIRTUAL OBJECTS.
Creator: Nguyen, Long, Malone, Linda, University of Central Florida
Abstract / Description: Interacting with a Virtual Environment (VE) generally requires the user to correctly perceive the relative position and orientation of virtual objects. For applications requiring interaction in personal space, the user may also need to accurately judge the position of the virtual object relative to that of a real object, for example, a virtual button and the user's real hand. This is difficult since VEs generally only provide a subset of the cues experienced in the real world....
Show moreInteracting with a Virtual Environment (VE) generally requires the user to correctly perceive the relative position and orientation of virtual objects. For applications requiring interaction in personal space, the user may also need to accurately judge the position of the virtual object relative to that of a real object, for example, a virtual button and the user's real hand. This is difficult since VEs generally only provide a subset of the cues experienced in the real world. Complicating matters further, VEs presented by currently available visual displays may be inaccurate or distorted due to technological limitations. Fundamental physiological and psychological aspects of vision as they pertain to the task of object manipulation were thoroughly reviewed. Other sensory modalities – proprioception, haptics, and audition – and their cross-interactions with each other and with vision are briefly discussed. Visual display technologies, the primary component of any VE, were canvassed and compared. Current applications and research were gathered and categorized by different VE types and object interaction techniques. While object interaction research abounds in the literature, pockets of research gaps remain. Direct, dexterous, manual interaction with virtual objects in Mixed Reality (MR), where the real, seen hand accurately and effectively interacts with virtual objects, has not yet been fully quantified. An experimental test bed was designed to provide the highest accuracy attainable for salient visual cues in personal space. Optical alignment and user calibration were carefully performed. The test bed accommodated the full continuum of VE types and sensory modalities for comprehensive comparison studies. Experimental designs included two sets, each measuring depth perception and object interaction. The first set addressed the extreme end points of the Reality-Virtuality (R-V) continuum – Immersive Virtual Environment (IVE) and Reality Environment (RE). This validated, linked, and extended several previous research findings, using one common test bed and participant pool. The results provided a proven method and solid reference points for further research. The second set of experiments leveraged the first to explore the full R-V spectrum and included additional, relevant sensory modalities. It consisted of two full-factorial experiments providing for rich data and key insights into the effect of each type of environment and each modality on accuracy and timeliness of virtual object interaction. The empirical results clearly showed that mean depth perception error in personal space was less than four millimeters whether the stimuli presented were real, virtual, or mixed. Likewise, mean error for the simple task of pushing a button was less than four millimeters whether the button was real or virtual. Mean task completion time was less than one second. Key to the high accuracy and quick task performance time observed was the correct presentation of the visual cues, including occlusion, stereoscopy, accommodation, and convergence. With performance results already near optimal level with accurate visual cues presented, adding proprioception, audio, and haptic cues did not significantly improve performance. Recommendations for future research include enhancement of the visual display and further experiments with more complex tasks and additional control variables.
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Date Issued: 2009
Identifier: CFE0002822, ucf:48060
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002822

Title: A FRAMEWORK TO ALIGN STRATEGY, IMPROVEMENT PERFORMANCE, AND CUSTOMER SATISFACTION USING AN INTEGRATION OF SIX SIGMA AND BALANCED SCORECARD.
Creator: Rodriguez, Adriana, Malone, Linda, University of Central Florida
Abstract / Description: This dissertation investigated the development, implementation, and evaluation of a management methodology founded on the alignment among the strategy, performance, and customer to bring value to any organization. A case study/action research in a service organization, called Institution "Z," provided the opportunity to assess the effects of the proposed Six Sigma Scorecard (SSS) methodology in the productivity indicators (measured by cycle time, line capacity, and number of errors). The Case...
Show moreThis dissertation investigated the development, implementation, and evaluation of a management methodology founded on the alignment among the strategy, performance, and customer to bring value to any organization. A case study/action research in a service organization, called Institution "Z," provided the opportunity to assess the effects of the proposed Six Sigma Scorecard (SSS) methodology in the productivity indicators (measured by cycle time, line capacity, and number of errors). The Case study/action research was conducted in three phases: Model and Concepts Design, Data Collection, and Findings. During the research, validity was pursued by using triangulation and theory to help maintain the case under research control. The observation of the SSS methodology in a real organization allowed the researcher to describe the merging process between Balanced Scorecard and Six Sigma methodology and their relationships to each other. The SSS methodology allowed identification of improvement projects that contribute to organizational strategy, implementation of strategies and provide feedback to the top level of management establishing alignment at three organizational levels – corporate, business, and functional. The results of the implementation of the SSS methodology in Institution Z showed a 40% improvement of the cycle time of the auto credit process, a 500% increase in the capacity of the process, and 65% decrease in the number of non-added value activities. During the same period of time, the BSC indicators showed a positive impact, specifically one financial indicator known as Level of Intermediation or GIC grew from 30% to 42% as it was expected by the end of the SSS implementation. The demonstration of the SSS framework in a Case study justifies the need for a combined methodology that aligns strategy, performance improvement and organizational outputs in a feedback loop. More research in this area is needed, especially investigations that include assessment studies where different management approaches are used alone and combined with strategic tools, and investigations that measure the relationship between level of coherence in the three merging points of the SSS and the results reached at the performance of the organization.
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Date Issued: 2008
Identifier: CFE0002191, ucf:47903
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002191

Title: A SURROGATE MEASURE OF CUSTOMER SATISFACTION IN THE MANUFACTURE OF PRINTED WIRING BOARDS.
Creator: maamoun, Adam, Malone, Linda, University of Central Florida
Abstract / Description: The objective of this research is to determine and develop a model that is capable of accurately measuring customer satisfaction for different industries and in particularly for the Printed Wiring Boards (PWB) Manufacturers. The new model will incorporate data not being collected or utilized by the survey method of determining customer satisfaction. The method used is a weighted average of satisfaction among several researched categories with percentages that accurately represent the relative...
Show moreThe objective of this research is to determine and develop a model that is capable of accurately measuring customer satisfaction for different industries and in particularly for the Printed Wiring Boards (PWB) Manufacturers. The new model will incorporate data not being collected or utilized by the survey method of determining customer satisfaction. The method used is a weighted average of satisfaction among several researched categories with percentages that accurately represent the relative importance of multiple facets of the PWB manufacturers customer satisfaction. A very common term in quality assurance is that "What is not measured accurately can not be evaluated or managed correctly," thus customer satisfaction is a very important aspect of any business, industry, or government. A satisfied customer will do more business and recommend it to other potential customers. Thus the business will grow and more revenues result. On the other hand, an unsatisfied customer will abandon the business and encourage more customers not to get involved with the same business so the business may decline and lose its market share and profitability. The categories that contribute to PWB customer satisfaction will be determined by conducting surveys among the leaders and best in the business of the PWB industry in addition to discovery of related articles that define the categories of the customer satisfaction for the PWB manufacturers. Once the categories are determined, the research concentrates on the weighting of the categories that most contribute to the PWB customer's satisfaction and a measure of satisfaction is derived. The model is easily applied to any other kind of PWB business or service industry. The model is based on empirical methods that will give an accurate measurement for the PWB customer's satisfaction. This in turn allows organizations the opportunity for improving customer satisfaction and increasing market share. The algorithm is based on characteristics deemed important by customers. Thus the customer satisfaction index can be computed and monitored on a regular basis without costly surveys. The major difference between this new model and the standard methods of determining customer satisfaction using the surveys is that this model will utilize data available with the proposals, sales, shipping, receiving, quality, engineering, manufacturing, and purchasing departments. The developed method to measure customer satisfaction utilizing internal data can be more cost effective, more accurate, can provide individual customer satisfaction scores, can measure whether or not these individual scores are statistically lower than the majority, and can provide satisfaction measures in real time none of which can be supplied by the survey method.
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Date Issued: 2008
Identifier: CFE0002219, ucf:47901
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002219

Title: PERCEIVED SERVICE QUALITY'S IMPACT ON BEHAVIORAL INTENTIONS IN THE TIMESHARE INDUSTRY.
Creator: Pollard, Leonard, Malone, Linda, University of Central Florida
Abstract / Description: This study created a model using factor analysis and structural equation modeling to investigate the relationship of service quality, word-of-mouth recommendation and price sensitivity of individuals who experienced a timeshare mini vacation at a branded timeshare resort. The constructs of service quality were developed by creating a survey tool. A total of 4,797 surveys were electronically sent resulting in a total of 1,275 of the individuals surveyed who met the criteria of staying at a...
Show moreThis study created a model using factor analysis and structural equation modeling to investigate the relationship of service quality, word-of-mouth recommendation and price sensitivity of individuals who experienced a timeshare mini vacation at a branded timeshare resort. The constructs of service quality were developed by creating a survey tool. A total of 4,797 surveys were electronically sent resulting in a total of 1,275 of the individuals surveyed who met the criteria of staying at a branded hotel or resort during their mini vacation. Six different variables were created from the ordinal level questions on the survey: Resort Accommodations, Sales Gallery, Sales Presentation, Resort Activities, Resort Staff and Brand Value. These were then used in an exploratory factor analysis to identify latent factors after which structural equation modeling was used to define the relationship between the factors and the independent variables. A total of 44 models were explored and evaluated based on goodness-of-fit metrics. The model that had the best level of fit was a first-order two-factor model. This model was created with an 80% subset and confirmed with a 20% subset of the sample. The factors found represent the Vacation Experience Promise (VEP) and the Vacation Experience Delivery (VED). There was a positive correlation for both VEP and VED with word-of-mouth recommendation and price sensitivity. The research also posited 24 hypotheses of the relationship between the service quality constructs, word-of-mouth recommendation and price sensitivity with the demographic characteristics of guest type, gender, stay type, age, marital status, gross income, timeshare ownership and the number of presentations attended. There was not enough information to support a relationship between the service quality constructs, word-of-mouth recommendation and price sensitivity with regards to gender, gross income and marital status. There was a difference in the scores for the service quality constructs and the varying categories within the age, stay type, and timeshare ownership demographic variables. There was a difference only in the VED scores and the varying categories within the guest type and presentations attended demographic variables. There was also a difference in the scores for the word-of-mouth recommendation construct and the varying categories within the age, guest type, timeshare ownership and number of presentations attended demographic variables. Lastly, there was also a difference in the scores for the price sensitivity construct and the varying categories within the guest type, timeshare ownership and presentation attended demographic variables. The research discusses the business implications associated with these findings and proposes next steps for future research.
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Date Issued: 2010
Identifier: CFE0003475, ucf:48942
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003475

Title: IMPROVING THROUGHPUT AND PREDICTABILITY OF HIGH-VOLUME BUSINESS PROCESSES THROUGH EMBEDDED MODELING.
Creator: DeKeyrel, Joseph, Malone, Linda, University of Central Florida
Abstract / Description: Being faster is good. Being predictable is better. A faithful model of a system, loaded to reflect the system's current state, can then be used to look into the future and predict performance. Building faithful models of processes with high degrees of uncertainty can be very challenging, especially where this uncertainty exists in terms of processing times, queuing behavior and re-work rates. Within the context of an electronic, multi-tiered workflow management system (WFMS) the author builds...
Show moreBeing faster is good. Being predictable is better. A faithful model of a system, loaded to reflect the system's current state, can then be used to look into the future and predict performance. Building faithful models of processes with high degrees of uncertainty can be very challenging, especially where this uncertainty exists in terms of processing times, queuing behavior and re-work rates. Within the context of an electronic, multi-tiered workflow management system (WFMS) the author builds such a model to endogenously quote due dates. A WFMS that manages business objects can be recast as a flexible flow shop in which the stations that a job (representing the business object) passes through are known and the jobs in the stations queues at any point are known. All of the other parameters associated with the flow shop, including job processing times per station, and station queuing behavior are uncertain though there is a significant body of past performance data that might be brought to bear. The objective, in this environment, is to meet the delivery date promised when the job is accepted. To attack the problem the author develops a novel heuristic algorithm for decomposing the WFMS's event logs exposing non-standard queuing behavior, develops a new simulation component to implement that behavior, and assembles a prototypical system to automate the required historical analysis and allow for on-demand due date quoting through the use of embedded discrete event simulation modeling. The developed software components are flexible enough to allow for both the analysis of past performance in conjunction with the WFMS's event logs, and on-demand analysis of new jobs entering the system. Using the proportion of jobs completed within the predicted interval as the measure of effectiveness, the author validates the performance of the system over six months of historical data and during live operations with both samples achieving the 90% service level targeted.
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Date Issued: 2011
Identifier: CFE0003580, ucf:48913
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003580

Title: ACCELERATED LIFE TESTING OF SUBSEA EQUIPMENT UNDER HYDROSTATIC PRESSURE.
Creator: Thiraviam, Amar Raja, Malone, Linda, University of Central Florida
Abstract / Description: Accelerated Life Testing (ALT) is an effective method of demonstrating and improving product reliability in applications where the products are expected to perform for a long period of time. ALT accelerates a given failure mode by testing at amplified stress level(s) in excess of operational limits. Statistical analysis (parameter estimation) is then performed on the data, based on an acceleration model to make life predictions at use level. The acceleration model thus forms the basis of...
Show moreAccelerated Life Testing (ALT) is an effective method of demonstrating and improving product reliability in applications where the products are expected to perform for a long period of time. ALT accelerates a given failure mode by testing at amplified stress level(s) in excess of operational limits. Statistical analysis (parameter estimation) is then performed on the data, based on an acceleration model to make life predictions at use level. The acceleration model thus forms the basis of accelerated life testing methodology. Well established accelerated models such as the Arrhenius model and the Inverse Power Law (IPL) model exist for key stresses such as temperature and voltage. But there are other stresses like subsea pressure, where there is no clear model of choice. This research proposes a pressure-life (acceleration) model for the first time for life prediction under subsea pressure for key mechanical/physical failure mechanisms. Three independent accelerated tests were conducted and their results analyzed to identify the best model for the pressure-life relationship. The testing included material tests in standard coupons to investigate the effect of subsea pressure on key physical, mechanical, and electrical properties. Tests were also conducted at the component level on critical components that function as a pressure barrier. By comparing the likelihood values of multiple reasonable candidate models for the individual tests, the exponential model was identified as a good model for the pressure-life relationship. In addition to consistently providing good fit among the three tests, the exponential model was also consistent with field data (validation with over 10 years of field data) and demonstrated several characteristics that enable robust life predictions in a variety of scenarios. In addition the research also used the process of Bayesian analysis to incorporate prior information from field and test data to bolster the results and increase the confidence in the predictions from the proposed model.
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Date Issued: 2010
Identifier: CFE0003411, ucf:48422
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003411

Title: OPTIMIZED MARKET INTRODUCTION OF LARGE CAPITAL PRODUCTS WITH LONG DEVELOPMENT AND LEARNING CYCLES.
Creator: Lembcke, Antje, Malone, Linda, University of Central Florida
Abstract / Description: Any product sold is expected to be reliable and available when the customer wants to operate it. Companies that produce large capital products (LCP), such as rockets, satellites, or large gas turbines to generate electrical energy, tend to shy away from extending their testing and validation method above the requirements by law, mainly due to the very high costs of each additional test and the uncertain return on investment. This research shows that todayÃ‚Â's state of...
Show moreAny product sold is expected to be reliable and available when the customer wants to operate it. Companies that produce large capital products (LCP), such as rockets, satellites, or large gas turbines to generate electrical energy, tend to shy away from extending their testing and validation method above the requirements by law, mainly due to the very high costs of each additional test and the uncertain return on investment. This research shows that todayÃ‚Â's state of the art validation methods for LCP, required by law, or suggested in literature, and adapted by these industries, are not capable of capturing all significant failure modes (or even enough failure modes), with the consequence that the subsequently sold commercial products will still experience failures with significant effects on product reliability, and subsequently on the companiesÃ‚Â' bottom line earnings projections. The research determines the type of data (significant variables) necessary to correlate a companyÃ‚Â's validation policy to product failures after commercialization, and predicts the financial impact of the current validation policy on the companyÃ‚Â's profitability. A systems dynamics model to assess a company's testing policy is developed and an optimized product validation plan is suggested, and its impact on a companyÃ‚Â's profitability is demonstrated through simulation. A generic methodology is derived and its viability is illustrated using a specific product and a dynamic model developed with data available to the researcher. The generic method can be applied by any company to develop its own model for optimizing product reliability prior to market introduction.
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Date Issued: 2010
Identifier: CFE0003413, ucf:48404
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003413

Title: THE INTEGRATED USER EXPERIENCE EVALUATION MODEL: A SYSTEMATIC APPROACH TO INTEGRATING USER EXPERIENCE DATA SOURCES.
Creator: Champney, Roberto, Malone, Linda, University of Central Florida
Abstract / Description: Evaluating the user experience (UX) associated with product interaction is a challenge for current human-systems developers. This is largely due to a lack of theoretical guidance for directing how best to assess the UX and a paucity of tools to support such evaluation. This dissertation provided a framework and tools for guiding and supporting evaluation of the user experience. This doctoral research involved reviewing the literature on UX, using this knowledge to build first build a...
Show moreEvaluating the user experience (UX) associated with product interaction is a challenge for current human-systems developers. This is largely due to a lack of theoretical guidance for directing how best to assess the UX and a paucity of tools to support such evaluation. This dissertation provided a framework and tools for guiding and supporting evaluation of the user experience. This doctoral research involved reviewing the literature on UX, using this knowledge to build first build a theoretical model of the UX construct and later develop a theoretical model to for the evaluation of UX in order to aid evaluators – the integrated User eXperience EValuation (iUXEV), and empirically validating select components of the model through three case studies. The developed evaluation model was subjected to a three phase validation process that included the development and application of different components of the model separately. The first case study focused on developing a tool and method for assessing the affective component of UX which resulted in lessons learned for the integration of the tool and method into the iUXEV model. The second case study focused on integrating several tools that target different components of UX and resulted in a better understanding of how the data could be utilized as well as identify the need for an integration method to bring the data together. The third case study focused on the application of the results of an usability evaluation on an organizational setting which resulted in the identification of challenges and needs faced by practitioners. Taken together, this body of research, from the theoretically-driven iUXEV model to the newly developed emotional assessment tool, extends the user experience / usability body of knowledge and state-of-practice for interaction design practitioners who are challenged with holistic user experience evaluations, thereby advancing the state-of-the-art in UX design and evaluation.
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Date Issued: 2009
Identifier: CFE0002761, ucf:48098
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002761

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