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Testing the reliability of an application usually requires a good usage model that accurately captures the likely sequences of inputs that the application will receive from the environment. The models being used in the literature are mostly based on Markov chains. They are used to generate test cases that are statistically close to what the applica-tion is expected to receive when in production. In this thesis, we propose a model for reli-ability testing that is created directly from the log file of a web application. Our proposed model is also based on Markov chains and has two components: one component, based on a modified tree, captures the most frequent behaviors, while the other component is another Markov chain that captures infrequent behaviors. The result is a statistically cor-rect model that shows clearly what most users do on the site. The thesis also presents an evaluation method for estimating the accuracy of vari-ous reliability-testing usage models. The method is based on comparison between ob-served users’ traces and traces inferred from the usage model. Our method gauges the accuracy of the reliability-testing usage model by calculating the sum of goodness-of-fit values of each traces and scaling the result between 0 and 1. Finally, we present an experimental study on the log of a real web site and discuss the way to use proposed usage model to generate test sequences, as well as strength and weakness of the model for reliability testing.

Testing the reliability of an application usually requires a good usage model that accurately captures the likely sequences of inputs that the application will receive from the environment. The models being used in the literature are mostly based on Markov chains. They are used to generate test cases that are statistically close to what the applica-tion is expected to receive when in production. In this thesis, we propose a model for reli-ability testing that is created directly from the log file of a web application. Our proposed model is also based on Markov chains and has two components: one component, based on a modified tree, captures the most frequent behaviors, while the other component is another Markov chain that captures infrequent behaviors. The result is a statistically cor-rect model that shows clearly what most users do on the site. The thesis also presents an evaluation method for estimating the accuracy of vari-ous reliability-testing usage models. The method is based on comparison between ob-served users’ traces and traces inferred from the usage model. Our method gauges the accuracy of the reliability-testing usage model by calculating the sum of goodness-of-fit values of each traces and scaling the result between 0 and 1. Finally, we present an experimental study on the log of a real web site and discuss the way to use proposed usage model to generate test sequences, as well as strength and weakness of the model for reliability testing.

This thesis aims to investigate the validity and reliability of the speaking exam at a Turkish University. For this study, data were obtained through questionnaires, interviews, the students&rsquo / speaking exam results, TOEFL exam results and departmental speaking exam scores. The results of the questionnaire were used to explore the face validity of the speaking exam. The interviews conducted to examine the content validity of the exam were analyzed in detail and common points from each interview were highlighted. To determine the predictive validity of the exam, Pearson Product Moment Correlation Coefficient and Simple Linear Regression Analysis were conducted. Furthermore, to investigate the construct validity of the exam correlation coefficients between speaking test scores and TOEFL subtest scores were calculated. To estimate the intra and inter-rater reliability level of the exam, correlation coefficients were calculated as well. The analysis of the results of the questionnaire indicated that the exam has satisfactory face validity. Moreover, the results of the interviews showed that the exam possesses the quality of content validity to a moderately high degree. It was found out that the speaking exam given in preparatory year education does not seem to predict the performances of the students in the departmental speaking exam. Moreover, the statistical analyses done to investigate the construct validity of the exam indicated that there are very low correlations between the speaking exam scores and the other subtests. It was discovered that the inter-rater reliability of the exam was not as satisfactory as it was expected as the inter-rater reliability of one pair was found relatively low. However, the speaking exam seemed to have satisfactory intra-rater reliability.

The purpose of this research study was to test the effects of an education/behavioral intervention on knowledge, perceived risk, and self-efficacy for sexually transmitted infections (STIs) prevention in women. Additionally, the instruments that measured knowledge of sexually transmitted infections and perceived risk were tested for reliability. Instruments used to test the effects of the intervention at pretest and following the intervention included the Sexually Transmitted Infection Knowledge Survey (Johnson-Mallard, 2002); the Perceived Risk for Sexually Transmitted Infection Survey (Johnson-Mallard, 2002); and the Sexual Self-Efficacy Survey (Heather and Pinkerton, 1998). Participants included 89-women seeking family planning services, sexually transmitted infection services or prenatal care at three county health units. Participants were randomly assigned to a treatment (n = 47) or control (n = 42) group. The treatment group received the theory based STI education/behavioral intervention. A logic model and Banduras Social Cognitive Theory were used to test the effects of an education/behavioral intervention on decreasing individual exposure to sexually transmitted infections by increasing individual knowledge, perceived risk, and self-efficacy. Data were analyzed using Analysis of Variance. Significantly differences from pretest to posttest was obtained between the experimental and control group on knowledge of STIs F (1, 87) = 73.66, p [less than] .001. Test results for the effect of the education/behavioral intervention on sexual self-efficacy resulted in significance difference between groups at posttest on refusing sexual intercourse F (1, 87) = 50.18, p [less than] .001; questioning potential sex partners F (1, 87) = 15.48, p [less than] .001; and condom use F (1, 87) = 19.60 p [less than] .001; indicating the brief (30-minute) education/behavioral intervention had an effect on the experimental group. However, posttest on STI perceived risk for women receiving the education/behavioral intervention did not approach significance F (1, 87) = .02 p [less than] .901 indicating the education/behavioral intervention did not have a statistically significant effect on the experimental group. The findings of the study indicate the importance of healthcare providers reinforcing STI information during clinical encounters with women.

Testing the reliability of an application usually requires a good usage model that accurately captures the likely sequences of inputs that the application will receive from the environment. The models being used in the literature are mostly based on Markov chains. They are used to generate test cases that are statistically close to what the applica-tion is expected to receive when in production. In this thesis, we propose a model for reli-ability testing that is created directly from the log file of a web application. Our proposed model is also based on Markov chains and has two components: one component, based on a modified tree, captures the most frequent behaviors, while the other component is another Markov chain that captures infrequent behaviors. The result is a statistically cor-rect model that shows clearly what most users do on the site. The thesis also presents an evaluation method for estimating the accuracy of vari-ous reliability-testing usage models. The method is based on comparison between ob-served users’ traces and traces inferred from the usage model. Our method gauges the accuracy of the reliability-testing usage model by calculating the sum of goodness-of-fit values of each traces and scaling the result between 0 and 1. Finally, we present an experimental study on the log of a real web site and discuss the way to use proposed usage model to generate test sequences, as well as strength and weakness of the model for reliability testing.

The long-term performance of TAH pumps needs to be demonstrated. Reliability tests are performed to measure its ability to operate for months, or years, without failure. Real Heart is currently constructing test rigs for this purpose. Software for documenting test rig conditions is also required. Thus, the objective of this study is to assist in developing reliability test rig software.  The software is written in LabVIEW and is hosted on a CompactRIO controller. Requirements include sampling of sensor data, logging, and alarms. Additionally, a PC dashboard is constructed for monitoring real-time data, reviewing logs, as well as controls for acquisition. Results of this study present a foundation for the test rig software. It features a modular architecture which allows for future scalability. The process of development involves research of hardware/software, establishing a reference design and to build and validate each module through test simulations. Data acquisition is set up with the NI-DAQmx API. It features automatic configuration for thermocouple, as well as custom signal scaling of the pressure and flow transducers. However, grouping of data and synchronization for logging and alarms was a challenge. The producer/consumer design pattern is implemented for grouping data as well as synchronization for logging and alarms. / Det artificiella hjärtats långsiktiga prestanda måste demonstreras. Tillförlitlighetstester utförs för att mäta pumparnas förmåga att fungera i månader eller år utan att gå sönder. Real Heart bygger för närvarande testriggar för detta ändamål. Programvara för att dokumentera testriggens förhållanden behövs också. Därför är syftet med denna studie att hjälpa företaget med att utveckla programvara för tillförlitlighetstestriggar.  Programvaran är skriven i LabVIEW och används på en CompactRIO-kontroller. Den kommer inkludera provtagning av sensordata, loggning och alarm. Dessutom är en PC-instrumentpanel konstruerad för övervakning av realtidsdata, granskning av loggar samt kontroll av datainsamling. Resultaten av denna studie utgör en grund för testriggens programvara. Den har en modulär arkitektur som möjliggör framtida uppskalning. Utvecklingsprocessen involverar studier av hårdvara/programvara, upprättande av en referensdesign, samt att bygga och validera varje modul genom testsimuleringar. Datainsamling genomförs med NI-DAQmx API. Den har automatisk konfiguration för temperatur, samt anpassad signalskalning av tryck- och flödesgivare. Designmönstret producent/konsument implementerades för gruppering av data, samt synkronisering för loggning och alarm.

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International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The Precision Fires Rocket and Missile Systems (PFRMS) Program Office continually undertakes Stockpile Reliability Testing (SRP) to ensure the validity of the accumulated weapons and increase the she lf life of these weapon systems. MLRS is a legacy weapon system that has been undergoing SRP testing for over 20 years. The PFRMS Program Office has a need for a miniature Tactical Telemetry System that will monitor the fuze performance of the MLRS Rocket during SRP testing. This paper will address a technical approach of how a small Tactical Telemetry System could be built to meet this requirement. The Tactical Telemetry system proposed in this paper will monitor fuze functions, operate across the wide environmental spectrum of the SRP tests, and physically fit in the nose area without altering the overall tactical rocket appearance or operation.

This study investigates the reliability of SnPb and SnAg solder joints in semiconductor packages subjected to thermal cycling. More specifically, solder joint crack growth and life are experimentally measured, and FEM models are run to explain the test results. Ultimately a life-prediction model is proposed for both SnPb and SnAg solder joint packages. Motorola 357-plastic ball grid array packages on printed wiring boards were thermal cycled with the following test parameters: SnPb and SnAg solders, three post-process conditions (aged, aircooled and quenched), four package layouts on the printed circuit boards (singledense, single-sparse, double-alternating, and double-dense), three accelerated thermal cycling protocols (0°C to 100°C, -40°C to 125°C, and -55°C to 125°C), and tests run at Motorola and the University of Texas. At predetermined thermal cycles, packages were removed from the environmental chambers, dyepenetrated, packages removed to expose the solder joints, and optical images taken. Images were processed to measure crack area, shape, orientation and length to show crack growth. Selected joints were sectioned and polished to investigate microstructure and failure modes. Selected boards were connected to an ANATECH event detector to monitor life from joint failures. FEM crack initiation and propagation models were developed to better understand failure mechanisms. Major experimental results are: 1) SnPb joints have about 50% faster crack growth rates than SnAg joints, subsequently SnPb joints have half the life of SnAg joints, 2) air-cooled and quenched packages had similar failure characteristics, but aged SnPb joints had lower life and aged SnAg joints had significantly longer life than the comparable nonaged joints, 3) double-dense package layout significantly decreased life (by 75%) over the other package layouts, which were similar to each other, 4) the test results at the two locations (UT and Motorola) were similar for SnPb solder joints, but significantly different for SnAg solder joints, and 5) the largest cracks occurred at the corners of joints just under the die edge. Major FEM simulation results are: 1) the crack initiation life of SnAg joints is approximately 100% longer than SnPb joints, 2) shear load is a major cause of crack growth, but the contribution of tensile load increases as the cracks grow, 3) primary cracks at the board interface appear to reduce the propagation rate of the primary crack on the package interface, 4) secondary cracks are suppressed when compressive stresses prevent voids from nucleating, 5) the double-dense configuration shows no PWB warping due to symmetry, and its stresses are larger than for the other package layouts, and (6) the stresses and strains for single-dense, single-sparse, and double-alternating package layouts are similar because the stresses/strains are dominated by local effects due to the CTE mismatch between the die and board. Based upon the experimental results and FEM simulations, a lifeprediction model based upon a severity metric was proposed. The metric estimates damage to the solder joints and links material properties and parameters associated with package layout and thermal test conditions to the time-dependent creep, time-independent plastic deformation, and a time-dependent and geometric effective stress of the solder. The severity metric predicted life very well for most of the data tested and was more accurate than the industry-standard life-prediction models for SnPb solder joints.