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Statistical modeling to improve the detection of glaucoma progressionKummet, Colleen 01 December 2013 (has links)
Glaucoma is the second leading cause of blindness affecting over 60 million people worldwide. The objectives of this study were to expand the existing methods of trend analysis in visual field time series data testing to aid in the early and accurate detection of glaucoma progression.
Visual field data including 54 locations for each of 140 eyes (one per participant among 96 cases and 44 controls) were evaluated using the Humphrey Field Analyzer II program 24-2 Swedish interactive thresholding algorithm (SITA) standard test strategy and Goldmann size III stimuli. One eye was randomly selected for the study and data were collected between 2003 and 2009. Two visual field examinations were conducted at baseline and at eight additional time points of visual field exams taken every six months for four years. Demographic, clinical, structural and other health data in the VIP study were collected from the electronic medical record and health questionnaires.
A variety of pointwise linear regression (PLR) criteria have been proposed for determining glaucomatous visual field progression. However, alternative PLR criteria have only been assessed on a limited basis. The first aim of this glaucoma progression detection study thoroughly examined PLR cut-point criteria to maximize the sensitivity and specificity of this standard tool in visual field analysis. The pointwise linear regression A2 (PLRA2) method was used to analyze the data, and Ocular Hypertension Treatment Study (OHTS) data were used to validate the decision rule.
Results showed that visual field trend analysis using PLR can be refined by adjusting the standard slope-based and significance level-based criteria. By considering more restrictive declines in visual field data (e.g., < -1.2dB/y, which is approximately 12 times the normal rate of age-related decay) and relaxing the significance level criterion of the PLR slope to p < 0.04 a high specificity can be maintained, while increasing the hit rate, i.e., the proportion of glaucoma cases in which progression was detected by PLR. This work serves to improve a familiar and commonly used method of time series visual field trend analysis that can be implemented quickly to improve early detection of glaucoma progression.
The second aim of this project was to investigate the performance of the nonlinear exponential and tobit regression models relative to the normal regression model in the analysis of visual field decay. The goodness-of-fit, as measured by Akaike Information Criteria (AIC), and rates of progression obtained by fitting three alternative regression models to longitudinal visual field data were compared at the location level. The results showed that visual field trend analysis using the tobit regression model results in a better model fit to visual field data, increased precision in the estimation of the rate of progression, and provides a specific advantage in modeling data from cases with advanced glaucoma.
The third, and final, aim of this glaucoma progression research project sought to determine if demographic, clinical and health factors, including intraocular pressure, retinal nerve fiber layer thickness, hypertension and diabetes, differ in participants whose visual field data are best fit overall by one statistical model compared to another. This was the first study to examine person-level factors that may affect the fit of proposed analysis models for visual field data, and to utilize bivariable and multivariable methods to understand patient-level predictors of visual field model fit. In the majority of eyes, the tobit model provided either a significantly better fit or there was no difference among models. Significant differences in patient characteristics included baseline MD and previous ocular surgery. This indicates that the tobit model may fit visual field time series data at least as well as the normal and nonlinear exponential models in all cases and controls; and in some advanced cases, it may provide a significantly improved fit.
This research overcame critical barriers in visual field trend analysis by increasing the sensitivity of PLR methods and further developing methods using alternative distributions to determine significant loss of function within each visual field test location. Furthermore, results of this study will contribute to the ongoing improvement of visual field trend analysis and the early detection and treatment of glaucoma progression.
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The validation of physiological field testing in elite orienteersRattray, Benjamin, n/a January 2002 (has links)
The complex physiology of orienteering performance is not well understood but recent
advances in technology allow for more in-depth investigation. The purpose of this
study was to develop and validate physiological field tests for elite orienteers in
Australia.
Seven male and three female elite orienteers volunteered to take part in the study.
Subjects completed an incremental fixed-distance (803m) trial in Australian forest
terrain, paced by a bicycle equipped with a speedometer. This was replicated in the
laboratory using a 4.5% grade for treadmill running. Subjects also completed four
(males) or three (females) laps of a 1340m terrain loop incorporating uphill, track and
downhill sections. Subjects then repeated this test in the laboratory, with treadmill grade
manipulated to replicate the gradient profile of each section. Heart rate (HR) and
oxygen uptake (VCh) were recorded continuously with telemetry during each stage/lap.
Blood [La] and RPE were recorded after each stage/lap.
In the incremental tests, no significant differences (p=0.05 level) were observed in HR,
VO2, blood [La] or RPE between the Field test, and its Laboratory replication over the
entire range of speeds tested. The actual speeds run during the Field tests were
significantly faster than the Laboratory test at the slowest speed (8 kmh- 1 ) attempted,
and slower at the fastest speed (18 km-h-1) attempted. In the time-trial tests, no
significant differences were observed in HR, VO2, blood [La] or RPE between the
Field test and its Laboratory replication. The running speeds in the Field tests were
significantly slower than the Laboratory tests. Running speed appeared inversely
related to the course profile and the terrain also affected the speeds that could be
achieved. Despite the changes in the course profile, the physiological responses to the
course were maintained within a narrow range at a high level (-95% of maximal heart
rate, 80-90% of VO2max, blood [La] -10 mM) for the duration of the 20-25 minute test.
The Field tests that were developed in this study for elite orienteers in Australian forest
terrain were successfully validated by replicating the protocols in a Laboratory setting.
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Design of an in-field Embedded Test ControllerShah, Ghafoor, Arslan, Saad January 2011 (has links)
Electronic systems installed in their operation environments often require regular testing. The nanometer transistor size in new IC design technologies makes the electronic systems more vulnerable to defects. Due to certain reasons like wear out or over heating and difficulty to access systems in remote areas, in-field testing is vital. For in-field testing, embedded test controllers are more effective in terms of maintenance cost than external testers. For in-field testing, fault coverage, high memory requirements, test application time, flexibility and diagnosis are the main challenges. In this thesis, an Embedded Test Controller (ETC) is designed and implemented which provides flexible in-field testing and diagnostic capability with high fault coverage. The ETC has relatively low memory requirements for storing deterministic test data as compared to storing complete test vectors. The test patterns used by the ETC are stored separately for each component of the device under test, in system memory. The test patterns for each component are concatenated during test application according to a flexible test command. To address test application time (which corresponds to down time of the system), two different versions of the ETC are designed and implemented. These versions provide a trade off between test application time and hardware overhead. Hence, a system integrator can select which version to use depending on the cost factors at hand. The ETC can make use of an embedded CPU in the Device Under Test (DUT), for performing test on the DUT. For DUTs where no embedded CPU is available, there is the additional cost of a test specific CPU for the ETC. To access the DUT during the test application, the IEEE 1149.1 (JTAG) interface is used. The ETC generates test result that provides information of failing ICs and patterns. The designed and implemented versions of the ETC are validated through experimentations. An FPGA platform is used for experimental validation of the ETC versions. A set of tools are developed for automating the experimental setup. Performance and hardware cost of the ETC versions are evaluated using the ITC'02 benchmarks.
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Τεχνικές ενσωματωμένου αυτοελέγχου για ορθή λειτουργία ψηφιακών ολοκληρωμένων συστημάτων στο πεδίο της εφαρμογήςΚουτσουπιά, Μαργαρίτα 04 December 2012 (has links)
Διάφορες μορφές κωδικοποίησης Huffman έχουν προταθεί για τη συμπίεση των
δεδομένων δοκιμής που χρησιμοποιούνται για τον έλεγχο της ορθής λειτουργίας
ολοκληρωμένων συστημάτων μετά την κατασκευή τους. Μεταξύ αυτών η βέλτιστη
επιλεκτική κωδικοποίηση Huffman παρουσιάζει διάφορα πλεονεκτήματα. Η
υιοθέτηση διαφορετικής τεχνικής ελέγχου της ορθής λειτουργίας του ολοκληρωμένου
συστήματος μετά την κατασκευή του και στο πεδίο της εφαρμογής αυξάνει το κόστος
του συστήματος. Για το λόγο αυτό στην εργασία αυτή διερευνούμε τη δυνατότητα
χρησιμοποίησης της βέλτιστης επιλεκτικής κωδικοποίησης τόσο μετά την κατασκευή
του ολοκληρωμένου συστήματος όσο και στο πεδίο της εφαρμογής. Τα συστήματα
που μας ενδιαφέρουν είναι τα ενσωματωμένα συστήματα πραγματικού χρόνου. Για
το λόγο αυτό μελετάμε καταρχήν τα χαρακτηριστικά που πρέπει να έχει η τεχνική
ελέγχου ορθής λειτουργίας στο πεδίο της εφαρμογής ανάλογα με τις απαιτήσεις ενός
ενσωματωμένου συστήματος. Σε κάθε περίπτωση μελετάμε το κόστος υλοποίησης
της τεχνικής ελέγχου τόσο σε κυκλώματα, σχεδιάζοντάς τα σε Verilog, όσο και στο
βαθμό συμπίεσης των δεδομένων δοκιμής, κάνοντας εξομοιώσεις σε C. / One-time factory testing of VLSI component after fabrication is insufficient in the deep submicron area. The products must be tested periodically in the field of application. Due to the complexity of the Systems on a Chip (SOCs), huge amounts of test data are required. However in many embedded systems the capacity of the available memory is a limited resource. In Automatic Test Equipment (ATE) based factory testing in order to reduce the memory requirements of the ATE and the time required to transfer the test data from ATE into the chip (and hence the test application time) various test set compression techniques have been proposed. In this paper we investigate the required enhancements so that an Optimal Selective Huffman Coding based test-set compression technique can be used for periodic testing in the field. The requirements of various types of periodic testing are examined depending on the criticality of the application running in embedded systems.
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Installation and Field Testing of High Performance Repair Materials for Pavements and Bridge DecksLesak, Andrew 10 December 2014 (has links)
No description available.
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Dynamic Testing and Modeling of a Superelevated Skewed Highway BridgeHardyniec, Andrew B. 15 September 2009 (has links)
Created in response to the aging infrastructure in the United States, the Long Term Bridge Performance Program (LTBPP) under the Federal Highway Administration (FHWA) proposes to assess the long-term performance of representative bridges through nondestructive evaluation (NDE) techniques and visual inspection. For consistency, a set of guidelines is needed to define the procedures for testing each bridge. The NDE techniques involve dynamic testing, and the protocol for this testing has yet to be finalized.
To evaluate the dynamic testing guidelines, a 103 ft single-span, simply supported highway bridge was dynamically tested. The test bridge was characterized by a skew of 34° and superelevation around 4%. Forced vibration testing involved an impact hammer with accelerometers measuring the response. Resonant frequencies were identified from the data by picking peaks from the magnitudes of the frequency response functions (FRF). Eleven modes were identified with frequencies ranging from 2.75 Hz to 22.5 Hz. Mode shapes associated with each mode were constructed using the imaginary components of the FRFs. The half-power bandwidth method was used to estimate the damping for each mode, with values ranging from 1% to 5% of critical damping.
Finite element (FE) models of the bridge were constructed in the commercial FE software Abaqus. The effects of adding and removing superelevation and skew, varying mesh refinement, and changing boundary conditions on modal parameters were thoroughly investigated. FE models were compared to the experimental results by directly comparing frequencies and using the modal assurance criterion to compare mode shapes. Support conditions of the actual structure were bounded using the results of the comparison.
Much insight was gained about forced vibration testing as applied to a full-scale bridge. The spectral resolution of the data proved to limit the accuracy and confidence of detecting closely-spaced modes and calculating damping estimates. Also, a more controlled method of exciting the structure was desired, such as using a shaker with a known input. Resonant frequencies of the FE models were sensitive to changes in boundary conditions, with some frequencies doubling. Both changes in boundary conditions and including skew and superelevation noticeably affected the mode shapes. When compared to the experimental results, the models with idealized roller and pin boundary conditions provided the best correlations based on resonant frequencies and mode shapes. / Master of Science
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A comparison of field and laboratory testing of sports specific fitness for female field hockey playersKusnanik, Nining Widyah, n/a January 2001 (has links)
There are many methods to measure the physical fitness of athletes, including tests
that can be applied in the field or in the laboratory. Much of the recent research with
regard to fitness of team sport players has been undertaken using laboratory testing to
measure aerobic power, anaerobic power and capacity, strength and flexibility. Field
tests are an alternative method to measure the fitness of players without the expense,
time and expertise required for the laboratory testing, especially in developing
countries.
The purpose of this study is to establish procedures for the application of
contemporary sports science practice for Indonesian female field hockey players,
including determination of the precision of field tests of the physical and performance
characteristics of field hockey players in Indonesia; determination of the physical and
performance characteristics of Indonesian female field hockey players; identification
of the performance demands and distance covered during competitive field hockey at
the national level in Indonesia; comparison of the physical and performance
characteristics of national level female field hockey players in Indonesia with those of
club level players in Australia; and determination of the relationships between field
and laboratory tests of physiological performance capacity for field hockey.
Due to conversion problems, five paragraphs have been omitted. For full abstract, see 01front.pdf.
In conclusion, the present study found that the Indonesian female field hockey players
(at the national level) were comparable to the Australian female field hockey players
(at the club level) in some physical and performance test results. However, they were
also different on other physical and performance characteristic measurements, with
the Indonesian players generally have lower values, for other performance
measurements.
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Concurrent Online Testing for Many Core Systems-on-ChipsLee, Jason Daniel 2010 December 1900 (has links)
Shrinking transistor sizes have introduced new challenges and opportunities for system-on-chip (SoC) design and reliability. Smaller transistors are more susceptible to early lifetime failure and electronic wear-out, greatly reducing their reliable lifetimes. However, smaller transistors will also allow SoC to contain hundreds of processing cores and other infrastructure components with the potential for increased reliability through massive structural redundancy. Concurrent online testing (COLT) can provide sufficient reliability and availability to systems with this redundancy. COLT manages the process of testing a subset of processing cores while the rest of the system remains operational. This can be considered a temporary, graceful degradation of system performance that increases reliability while maintaining availability.
In this dissertation, techniques to assist COLT are proposed and analyzed. The techniques described in this dissertation focus on two major aspects of COLT feasibility: recovery time and test delivery costs. To reduce the time between failure and recovery, and thereby increase system availability, an anomaly-based test triggering unit (ATTU) is proposed to initiate COLT when anomalous network behavior is detected. Previous COLT techniques have relied on initiating tests periodically. However, determining the testing period is based on a device's mean time between failures (MTBF), and calculating MTBF is exceedingly difficult and imprecise.
To address the test delivery costs associated with COLT, a distributed test vector storage (DTVS) technique is proposed to eliminate the dependency of test delivery costs on core location. Previous COLT techniques have relied on a single location to store test vectors, and it has been demonstrated that centralized storage of tests scales poorly as the number of cores per SoC grows. Assuming that the SoC organizes its processing cores with a regular topology, DTVS uses an interleaving technique to optimally distribute the test vectors across the entire chip. DTVS is analyzed both empirically and analytically, and a testing protocol using DTVS is described.
COLT is only feasible if the applications running concurrently are largely unaffected. The effect of COLT on application execution time is also measured in this dissertation, and an application-aware COLT protocol is proposed and analyzed. Application interference is greatly reduced through this technique.
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Development of a Novel Method for Lithium-Ion Battery Testing on Heavy-Duty VehiclesSvens, Pontus January 2011 (has links)
Increasing demands for lower environmental impact from vehicles, including heavy-duty vehicles, have driven several vehicle manufacturers to consider adding hybrid electrical vehicles (HEV’s) to the product portfolio. Present research on batteries for HEV’s is mainly focused on lithium-ion battery chemistries, since lithium-ion batteries has the most promising technical potential compared to other types of batteries. However, the uncertainty regarding battery lifetime combined with a high battery cost can have a negative impact on large scale commercialisation of heavy-duty hybrid vehicles in the near future. A large part of present lithium-ion battery research is focused on new materials, but there is also research focusing on ageing of already established lithium-ion battery chemistries. Cycle ageing of batteries often includes complete charging and discharging of batteries or the use of standardized test cycles. Battery cycling in real HEV applications is however quite different compared to this kind of laboratory testing, and real life testing on vehicles is a way of verifying the soundness of laboratory ageing. The aim of this study was to develop a test method suitable for real life testing of lithium-ion batteries for heavy-duty HEV-usage, with the purpose of investigating the correlation of battery ageing and usage in real life applications. This concept study includes both cell level battery cycling and performance testing on board vehicles. The performance tests consist of discharge capacity measurements and hybrid pulse power characterization (HPPC) tests. The main feature of this test equipment is that it is designed to be used on conventional vehicles, emulating an HEV environment for the tested battery. The functionality of the equipment was verified on a heavy-duty HEV with satisfying results. Results from real life testing of 8 batteries using the developed test equipment on four conventional heavy-duty trucks shows that the concept of comparing battery ageing with battery usage has a most promising potential to be used as a tool when optimizing battery usage vs. lifetime. Initial results from this real life study shows significant differences in state of charge (SOC) and power distributions between cycled batteries, but so far only small differences in ageing. Lithium-ion batteries of the type lithium manganese spinel/lithium titanate (LMO/LTO) were used in this study. / Ökande krav på minskad miljöpåverkan från fordon, inklusive tunga fordon, har drivit flera fordonstillverkare till att addera hybridiserade fordon till produktportföljen. Forskning på hybridfordonsbatterier är idag huvudsakligen inriktad på litiumjonbatterikemier, vilken har den mest lovande tekniska potentialen jämfört med andra typer av batterikemier. Det finns idag en risk att osäkerheten kring litiumjonbatteriers livslängd i kombination med en hög batterikostnad kan ha en negativ inverkan på en storskalig kommersialisering av tunga hybridfordon inom den närmsta framtiden. En stor del av batteriforskningen är inriktad på nya material, men det finns även forskning som fokuserar på åldring av redan etablerade litiumjonbatterikemier. Vid åldringsprov används ofta standardiserade testcykler eller cykler där batterierna blir fullständigt laddade och urladdade. Cykling av batterier i verkliga förhållanden skiljer sig dock från den typen av laboratorietester och provning på fordon är därför ett sätt att kontrollera att laboratorieprovning ger relevanta resultat gällande åldring. Syftet med denna studie var att utveckla en testmetodik lämplig för provning av litiumjonbatterier för tunga hybridfordon i verklig drift, med syfte att undersöka kopplingen mellan batteriers åldrande och hur det används. Detta koncept inkluderar battericykling på cellnivå och möjligheten att utföra batteriprestandatester på fordon, där prestandatesterna består av kapacitetsprov och pulsprov. Den viktigaste egenskapen hos den utvecklade testmetodiken är att provning sker på konventionella fordon genom att emulera en hybridmiljö för det testade batteriet. Funktionaliteten hos den utvecklade testutrustningen verifierades på en tung hybridlastbil med goda resultat. Resultaten från en fältstudie av 8 batterier på 4 lastbilar där den utvecklade testutrustningen användes påvisar att testmetodiken har en lovande potential att kunna användas som ett verktyg vid optimering av utnyttjandegrad och livslängd för HEV-batterier. De initiala resultaten från denna fältstudie påvisar skillnader i laddningsgradsfördelning och batterieffektfördelning mellan cyklade batterier, men ännu bara små skillnader i åldring. Litiumjonbatterier av typen litiummanganspinel/litiumtitanat (LMO/LTO) användes i denna studie. / QC 20111205
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Dynamic Testing for a Steel Truss Bridge for the Long Term Bridge Performance ProgramSantos, Cody Joshua 01 May 2011 (has links)
Under the direction of the Federal Highway Administration the Long Term Bridge Performance Program (LTBP) selected Minnesota Bridge number 5718 as a pilot bridge for evaluation. This program focuses on the monitoring of bridges for a 20-year period to understand the structural behavior over time due to the various loads and weathering. In monitoring this bridge a better understanding can be acquired for the maintenance issues related to the nation's deteriorating bridge infrastructure.
Bridge Number 5718, which is located just outside of Sandstone Minnesota, is a steel truss bridge that spans the Kettle River. Constant monitoring of the bridge along with periodic testing of the bridge will allow for the collection of data over a 20-year period. The focus of this work is to establish a baseline for the bridges characteristics through nondestructive dynamic testing. Later tests will be compared to these results and changes can then be tracked.
In order to perform the required testing, two electromagnetic shakers were used to produce the excitation. The bridge was also outfitted with an array of velocity transducers to allow for the response to be recorded. The data was then used to extract the resonant frequencies, mode shapes, and damping ratios. A modal assurance criterion was also performed to solidify the findings. These parameters define the structural identity of the bridge. Through performing these tests the database that is being collected under the Long Term Bridge Performance Program will be used to better the overall health and safety of the nation's bridges.
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