Acquisition of 3D model of real objects and scenes is indispensable and useful in many practical applications, such as digital archives, game and entertainment industries, engineering, advertisement. There are 2 main methods for 3D acquisition : laser-based reconstruction (active method) and image-based reconstruction from multiple images of the scene in different points of view (passive method). While laser-based reconstruction achieves high accuracy, it is complex, expensive and difficult to set up for large-scale outdoor reconstruction. Image-based, or multi-view stereo methods are more versatile, easier, faster and cheaper. By the time we begin this thesis, most multi-view methods could handle only low resolution images under controlled environment. This thesis targets multi-view stereo both both in large scale and high accuracy issues. We significantly improve some previous methods and combine them into a remarkably effective multi-view pipeline with GPU acceleration. From high-resolution images, we produce highly complete and accurate meshes that achieve best scores in many international recognized benchmarks. Aiming even larger scale, on one hand, we develop Divide and Conquer approaches in order to reconstruct many small parts of a big scene. On the other hand, to combine separate partial results, we create a new merging method, which can merge automatically and quickly hundreds of meshes. With all these components, we are successful to reconstruct highly accurate water-tight meshes for cities and historical monuments from large collections of high-resolution images (around 1600 images of 5 M Pixel images)

This study explores the accuracy of prevalence estimations for suicide attempts. Data came from the Early Developmental Stages of Psychopathology (EDSP) Study, a prospective community study (mean follow-up period was 42 months) of 3,021 respondents aged 14 to 24 years at the outset of the study. Suicide attempters are at least 1.6 times more likely to drop out than subjects with no suicide attempts and suicidal ideas. A total of 8% of all suicide attempters answered in the negative the depression-related gate questions of all surveys. One-third of all baseline suicide attempters did not report their suicide attempt again at the four years later assessment. In particular, 80% of all nonreporters were female, and almost 60% were aged 14–17 at baseline.

Nondestructive evaluation of civil structures is of increasing interest to utility owners. Several methods exist to evaluate different properties of concrete, pavement, cemented sands and others. UPVM is the most commonly used ultrasonic technique in civil structures due to its simplicity and ease of use. UPVM is fast and requires minimal skill from operators. It has been used for flaw detection, study of material contents, deduction of general deterioration, determination of elastic properties , measurement of strength, and others. In such applications, accurate measurements of velocity are essential for proper parameter evaluation and thus to increase the validity of conclusions obtained from measurements. Previous research in ultrasonic pulse velocity have found that UPVM are susceptible to specimen size, attenuation and frequency but no clear conclusions have yet to be made on the fundamental reason for the differences. This work seeks to identify the main factors responsible for velocity differences due to specimen size and measuring frequency in civil engineering materials. The effects are investigated by first performing numerical simulations of concrete specimens of varying sizes, and properties, excited by both a low (55 kHz) and high (850 kHz) frequency input source. Simulations are used to model wave propagation in cylindrical concrete specimen. Transducer sound fields are also numerically studied using known analytical solutions. An experimental program is conducted to study variations in UPVM in 12 mortar and 11 concrete cylindrical specimens of varying widths and heights caused by different measuring frequencies. Simulations are completed for 12 specimen of different dimensions having heights of 5,10,20 and 30 cm as well as diameters of 10, 20 and 30 cm. Both a low (f = 55 kHz) and high (f = 850 MHz) frequency input source are used on each specimen. Numerical simulations using low frequencies are made for both a damped and undamped series of specimen. Results from low frequency simulations of damped models indicate that wave attenuation can lead to significant errors in first arrivals when complex wave interference is present. Conditions for wave interference at the receiver location are studied and minimum size conditions for both height and width are derived. These conditions guarantee proper pulse separation for UPVM and are dependent on source size, and source pulse width. It is argued that with proper use these conditions will lead to accuracy of measurement better than one quarter of a period of the main excitation frequency when using a full waveform and a skilled operator. Finally, experiments are performed to assess differences in first arrivals between high and low frequency measurements. Readings are made on 11 mortar and 12 concrete specimen of different heights and widths. Experimentally significant time differences are observed between high and low frequency readings. It is found that differences in first arrivals will increase with specimen length but differences in velocity will decrease with length. Specimens 4 wavelengths in height are deemed sufficient to diminish surface effects to a minimum provided the specimens are healthy (e.g. no internal flaws). Any increase past 4 wavelengths is found to have negligible effects on measured velocity in healthy specimens.

The modern medical diagnostic systems are based on the techniques using digital data formats – a natural feed for the computer based systems. With the use of modern diagnostic techniques the diagnosis process is becoming more complex as many diseases seem to have the same pre-symptoms at early stages. And of course computer based systems require more efficient and effective ways to identify such complexities. However, the existing formalisms for knowledge representation, tools and technologies, learning and reasoning strategies seem inadequate to create meaningful relationship among the entities of medical data i.e. diseases, symptoms and medicine etc. This inadequacy actually is due to the poor design of the knowledge base of the medical system and leads the medical systems towards inaccurate diagnosis. This thesis discusses the limitations and issues specific to the design factors of the knowledge base and suggests that instead of using the deficient approaches and tools for representing, learning and retrieving the accurate knowledge, use of semantic web tools and techniques should be adopted. Design by contract approach may be suitable for establishing the relationships between the diseases and symptoms. The relationship between diseases and symptoms and their invariants can be represented more meaningfully using semantic web. This can lead to more concrete diagnosis, by overcoming the deficiencies and limitations of traditional approaches and tools.

A satellite in orbit about a planet needs some means of attitude control in order to, for instance, get as much sun into its solar-panels as possible. It is easy to understand that, for example, a spy satellite has to point at a certain direction without the slightest trembling to get a photo of a certain point on the earth. This type of mission must not exceed an error in attitude of more then about 1/3600 degrees. But, since high accuracy equals high cost, it is also easy to understand why a research satellite measuring solar particles (or radiation) in space does not need high accuracy at all. A research vessel of this sort can probably do with less accuracy then 1 degree. The first part of this report tries to explain some major aspects of satellite space-flight. It continues to focus on the market for small satellites, i.e. satellites weighing less than 500 kg. The second part of this final thesis work deals with the development of a program that simulates the movement of a satellite about a large celestial body. The program, called AOSP, consists of user-definable packages. Sensors and estimation filters are used to predict the satellites current position, velocity, attitude and angular velocity. The purpose of the program, which is written in MATLAB, is to easily determine the pointing accuracy of a satellite when using different sensors and actuators.

Nondestructive evaluation of civil structures is of increasing interest to utility owners. Several methods exist to evaluate different properties of concrete, pavement, cemented sands and others. UPVM is the most commonly used ultrasonic technique in civil structures due to its simplicity and ease of use. UPVM is fast and requires minimal skill from operators. It has been used for flaw detection, study of material contents, deduction of general deterioration, determination of elastic properties , measurement of strength, and others. In such applications, accurate measurements of velocity are essential for proper parameter evaluation and thus to increase the validity of conclusions obtained from measurements. Previous research in ultrasonic pulse velocity have found that UPVM are susceptible to specimen size, attenuation and frequency but no clear conclusions have yet to be made on the fundamental reason for the differences. This work seeks to identify the main factors responsible for velocity differences due to specimen size and measuring frequency in civil engineering materials. The effects are investigated by first performing numerical simulations of concrete specimens of varying sizes, and properties, excited by both a low (55 kHz) and high (850 kHz) frequency input source. Simulations are used to model wave propagation in cylindrical concrete specimen. Transducer sound fields are also numerically studied using known analytical solutions. An experimental program is conducted to study variations in UPVM in 12 mortar and 11 concrete cylindrical specimens of varying widths and heights caused by different measuring frequencies. Simulations are completed for 12 specimen of different dimensions having heights of 5,10,20 and 30 cm as well as diameters of 10, 20 and 30 cm. Both a low (f = 55 kHz) and high (f = 850 MHz) frequency input source are used on each specimen. Numerical simulations using low frequencies are made for both a damped and undamped series of specimen. Results from low frequency simulations of damped models indicate that wave attenuation can lead to significant errors in first arrivals when complex wave interference is present. Conditions for wave interference at the receiver location are studied and minimum size conditions for both height and width are derived. These conditions guarantee proper pulse separation for UPVM and are dependent on source size, and source pulse width. It is argued that with proper use these conditions will lead to accuracy of measurement better than one quarter of a period of the main excitation frequency when using a full waveform and a skilled operator. Finally, experiments are performed to assess differences in first arrivals between high and low frequency measurements. Readings are made on 11 mortar and 12 concrete specimen of different heights and widths. Experimentally significant time differences are observed between high and low frequency readings. It is found that differences in first arrivals will increase with specimen length but differences in velocity will decrease with length. Specimens 4 wavelengths in height are deemed sufficient to diminish surface effects to a minimum provided the specimens are healthy (e.g. no internal flaws). Any increase past 4 wavelengths is found to have negligible effects on measured velocity in healthy specimens.

There have been increased efforts to develop methods for improving attention across a range of tasks including those assessing sustained attention. Using a variety of techniques, researchers have reported modest reductions in errors on sustained attention tasks. However, published reports often have not documented changes in response times (RTs) that might accompany error reductions, which is problematic given that the error reductions could be mediated by a slowing strategy (i.e., speed-accuracy trade-off). In three studies, I explored the effects of speed-accuracy trade-offs in a sustained attention task (The Sustained Attention to Response Task; SART). In Study 1, I examined the effects of changing SART instructions from the double-edged "be fast and accurate" to the more conceptually accurate goal of maintaining high accuracy by responding slowly and carefully, and found that instructions to respond slowly and accurately resulted in both significantly longer RTs and fewer SART errors. In Studies 2 and 3, I developed a modified version of the SART that allowed me to experimentally manipulate RTs and found that errors were a systematic function of manipulated differences in RT independent of individual differences in response strategies. The results of these experiments indicate that it is possible that any technique that alters RT might indirectly alter error rates independently of improvements in sustained attention. I therefore conclude that investigators need to carefully attend to, control for, and report any changes in RT that accompany improvements in accuracy of performance, or alternatively employ tasks controlling for RT.

Study Design: A blinded, prospective diagnostic test study was conducted.<p>Objectives: To assess the inter-tester reliability of clinical examination items for carpal tunnel syndrome (CTS), to assess the validity of individual clinical test items and self-report measures for the diagnosis of CTS and to assess the accuracy of an optimum test item cluster for the diagnosis of CTS.<p>Study Rational: Examination of the diagnostic validity of various clinical tests for the diagnosis of CTS has shown mixed results and the reliability of many of these tests has not been determined. The majority of the diagnostic validity research for CTS has examined tests individually which is in contrast to clinical practice where the results of multiple tests are combined as part of the clinical reasoning process in order to formulate a differential diagnosis: the test item cluster, derived through logistic regression, is proposed as a means to integrate the validity of multiple tests. Methods: 37 subjects (74 hands) were recruited from a convenience sample of consecutive patients referred to for electrodiagnostic (EDX) testing due to upper extremity symptomatic complaints. Subjects underwent EDX testing followed by completion of self-report questionnaires and a standardized clinical examination by examiners blinded to EDX results. Diagnostic validity was determined for both general and restricted CTS classification groupings. <p>Results: Out of 18 clinical test items, 12 had reliability coefficients (i.e. ICC or Kappa) of .40 or greater. There were 10 clinical exam and self-report items that were found to have likelihood point estimates above 2 or below 0.50 for the general diagnostic classification and 6 items had acceptable validity for the restricted classification. The test item cluster (TIC) derived for the general classification included hand numbness and symptom reproduction with the upper limb neurodynamic test 1. The TIC derived for the restricted classification included hand numbness and the overall score of the symptom component of the Bringham Carpal Tunnel Questionnaire. The 95% confidence intervals for most likelihood ratio point estimates were wide. <p>Conclusions: The TICs for both classification groupings did not yield improved diagnostic validity beyond that found with the single best test item (hand numbness). The value of the single best test item hand numbness was in a negative response. Further investigation is required to validate the TIC and the single best test item and to improve the point estimate precision.

Recent computational models and physiological studies suggest that simple, two-alternative forced-choice decision making can be conceptualized as the gradual accumulation of sensory evidence. Accordingly, information is sampled over time from a sensory stimulus, giving rise to an activation function. A response is emitted when this function reaches a criterion level of activity. Critically, the phenomenon known as speed-accuracy tradeoff (SAT) is modeled as a shift in the response boundaries (criterion). As speed stress increases and criterion is lowered, the information function travels less distance before reaching threshold. This leads to faster overall responses, but also an increase in error rate, given that less information is accumulated. Psychophysiological data using EEG and single-unit recordings from monkey cortex suggest that these accumulator models are biologically plausible. The present work is an effort to strengthen this position. Specifically, it seeks to demonstrate a neural correlate of criterion and demonstrate its relationship to behavior. To do so, subjects performed a letter discrimination paradigm under three levels of speed stress. At the same time, electroencephalogram (EEG) was used to derive a measure known as the lateralized readiness potential, which is known to reflect ongoing motor preparation in motor cortex. In Experiment 1, the amplitude of the LRP was related to speed stress: as subjects were forced to respond more quickly, less information was accumulated before making a response. In other words, criterion lowered. These data are complicated by Experiment 2, which found that there are boundary conditions for this effect to obtain.

Hurricane Katrina of 2005 was responsible for at least 81 billion dollars of property damage. In planning for such emergencies, society must decide whether to invest in the ability to evacuate more speedily or in improved forecasting technology to better predict the timing and intensity of the critical event. To address this need, we use dynamic programming and Markov processes to model the interaction between the emergency response system and the emergency forecasting system. Simulating changes in the speed of evacuation and in the accuracy of forecasting allows the determination of an optimal mix of these two investments. The model shows that the evacuation improvement and the forecast improvement give different patterns of impact to their benefit. In addition, it shows that the optimal investment decision changes by the budget and the feasible range of improvement.