Evaluation of the seismic stability of slopes often involves an estimate of the expected sliding displacements. This evaluation requires a suite of acceleration-time histories as input motions. The methods of selecting and scaling these motions can affect the computed sliding displacements. Linear scaling of recorded ground motions and modification of recorded motions by spectral matching are common approaches used for ground motion selection and these approaches were used in this study to select motions for use in sliding displacement analyses. Rigid sliding block analyses and decoupled flexible sliding block analyses were performed using a suite of linearly scaled motions and a suite of spectrally matched motions. . Generally, the spectrally matched motions predict 10 to 30%, on average, smaller displacements and significantly less variability than the linearly scaled motions, when both suites of input motions were developed to match the same acceleration response spectrum. When both suites of input motions were developed to match the same peak ground velocity and acceleration response spectrum, the spectrally matched motions generally predict 5 to 15%, on average, larger displacements than the linearly scaled motions. Because ground motion parameters beyond acceleration response spectrum affect the computed sliding displacement, parameters such as peak ground acceleration (PGA), peak ground velocity (PGV) and mean period (T[subscript m]) should be considered in selecting and scaling motions for use in sliding displacement analyses. / text

In bridge deck concrete, early-age cracking can lead to substantial serviceability and structural integrity issues over the lifespan of the bridge. An understanding of the temperature, stress, and strength development of concrete can aid determining the early-age cracking susceptibility. This project, funded by the Texas Department of Transportation, evaluated these properties for various bridge deck materials and mixture proportions. The research presented in this thesis involved a laboratory testing program that used a combination of semi-adiabatic calorimetry, rigid cracking frame, free shrinkage frame, and match cured cylinder testing program that allowed the research team to simulate the performance of common bridge deck mixture designs under hot and cold weather conditions. In this program, the semi-adiabatic calorimetry was used, with previously generated models, to generate the temperature profile of the mixture. The rigid cracking frame and free shrinkage frame were used to evaluate the restrained stress development and the unrestrained volume changes, respectively, under the simulated temperatures. The match-cure cylinder testing program allowed the research team to generate a strength development profile for the concrete mixtures under the various simulated temperature profiles. Results from the laboratory program revealed that in hot weather simulations, ground granulated blast furnace slag mixtures developed the lowest stress / strength ratios, and in cold weather simulations, Class F fly ash mixtures developed the lowest stress / strength ratios. In general, use of SCMs and limestone coarse aggregate results in mixtures that generate less heat and lower stress / strength ratios. Isothermal testing showed that shrinkage reducing admixtures were effective in reducing early-age strains from chemical shrinkage. In addition to the laboratory testing program, a field testing program was completed to measure the temperature development of four bridge decks during the winter and summer months. The recorded concrete temperatures and the effects of the environmental conditions at the time of the pour will aid in the calibration and validation of the temperature prediction component of ConcreteWorks for bridge deck construction. In addition, experience gained through these field pours resulted in an optimized instrumentation procedure that will aid in the successful collection of data in future projects. / text

Στη διδακτορική διατριβή μελετώνται πέντε διαφορετικά προβλήματα που συναντώνται στη δημιουργία ενός συστήματος εκτίμησης ανακλαστικότητας χρώματος αντικειμένων και ποιοτικού ελέγχου έγχρωμων επίπεδων επιφανειών με σχέδια. Το πρώτο πρόβλημα αφορά στην εξαγωγή της απόκρισης φωτεινότητας της κάμερας που θα χρησιμοποιηθεί στο σύστημα. Για την εκτίμησή της προτάθηκαν τέσσερις μέθοδοι (δύο παραμετρικές και δύο μη παραμετρικές) που κάνουν χρήση των δεδομένων πολλαπλών εικόνων τυχαίων σκηνών. Η απόκριση φωτεινότητας εκτιμάται με χρήση πρωτότυπων συστημάτων εξισώσεων υπό περιορισμούς. Το δεύτερο πρόβλημα αφορά την εκτίμηση της φασματικής απόκρισης της κάμερας. Προτείνεται μία νέα μέθοδος που χρησιμοποιεί μοντέλο αθροίσματος κανονικών κατανομών και γενετικό αλγόριθμο. Η μέθοδος αυτή παρουσιάζει ανώτερη απόδοση σε σχέση με άμεσα ανταγωνιστικές μεθόδους στην εκτίμηση των φασματικών αποκρίσεων. Το τρίτο πρόβλημα αφορά επιλογή οπτικών φίλτρων από διαθέσιμο σύνολο για την κατασκευή πολυκαναλικού συστήματος εκτίμησης της φασματικής ανακλαστικότητας αντικειμένων. Προτείνονται νέες προσεγγίσεις με ανώτερη ακρίβεια φασματικής ανακατασκευής ανακλαστικοτήτων σε σχέση με ανταγωνιστικές μεθόδους. Το τέταρτο πρόβλημα αφορά στην επίτευξη χρωματικής ισοστάθμισης. Προτείνεται μία νέα παραδοχή μεγιστοποίησης της αντίθεσης στο κανάλι της φωτεινότητας. Με βάση την παραδοχή αυτή προτείνονται νέες μέθοδοι χρωματικής ισοστάθμισης και συγκρίνονται με υπάρχουσες στη βιβλιογραφία. Τα αποτελέσματα είναι συγκρίσιμα ή και ανώτερα ανταγωνιστικών μεθόδων. Το πέμπτο πρόβλημα αφορά στη δημιουργία συστήματος ανίχνευσης σφαλμάτων σε έγχρωμες επίπεδες επιφάνειες. Προτείνεται ένα πρωτότυπο σύστημα εντοπισμού σφαλμάτων που βασίζεται στην σύγκριση διανυσμάτων χαρακτηριστικών τοπικών ιστογραμμάτων σε πολλαπλά επίπεδα ανάλυσης και χρωματικά κανάλια. Τα διανύσματα χαρακτηριστικών είναι ανεξάρτητα από περιστροφή και μετατόπιση και ανεκτικά σε παραμορφώσεις. Η μέθοδος απαιτεί την ύπαρξη δειγμάτων αναφοράς για εκπαίδευση. Με έναν πρωτότυπο αλγόριθμο εντοπισμού σφαλμάτων, που χρησιμοποιεί τα δεδομένα που αποκτήθηκαν από τα δείγματα αναφοράς, γίνεται εντοπισμός των σφαλμάτων στις εικόνες επισκόπησης. Το σύστημα αξιολογείται όσον αφορά στην απόδοσή του χρησιμοποιώντας μία βάση δεδομένων εικόνων η οποία περιέχει τεχνητά σφάλματα και δημιουργήθηκε για το σκοπό αυτό. / This dissertation analyzes five different problems on the development of an image based reflectance reconstruction system for defect detection on colour patterned planar objects. The first problem involves the estimation of the camera’s photoquantimetric response. Four new methods are proposed (two parametric and two non-parametric) using multiple images of the same static scene. The photoquantimetric response is estimated by the use of a novel formulation of linear systems with restrictions. The second problem refers to the estimation of the camera’s spectral response. Through the use of a sum of Gaussian model combined with genetic algorithms a new formulation is achieved. This new method shows improved performance compared to previous approaches. The third problem involves the selection of a subset of optical filters from an available set for the development of a multispectral reflectance reconstruction system. New approaches are proposed based on statistical features of the system responses providing better reflectance reconstruction accuracy in comparison to previous methods. The fourth problem refers to colour constancy. A novel assumption is proposed based on contrast maximization in the intensity channel. New methods based on this assumption are proposed. These new methods show comparable or even superior performance to existing colour constancy methods. The fifth problem involves the development of a defect detection system for coloured patterned planar surfaces. A novel defect detection system is proposed based on the comparison of statistical local feature vectors at multiple scales of resolution. The features used are rotation and translation invariant and robust to non-linear deformations. The system requires the existence of defect free reference patterns. A novel defect detection algorithm is proposed and tested on a database especially created for the task with satisfying results.

Precision optics can be accurately fabricated by computer controlled optical surfacing (CCOS) that uses well characterized polishing tools driven by numerically controlled machines. The CCOS process is optimized to vary the dwell time of the tool on the workpiece according to the desired removal and the calibrated tool influence function (TIF), which is the shape of the wear function by the tool. This study investigates four major topics to improve current CCOS processes, and provides new solutions and approaches for the next generation CCOS processes.The first topic is to develop a tool for highly aspheric optics fabrication. Both the TIF stability and surface finish rely on the tool maintaining intimate contact with the workpiece. Rigid tools smooth the surface, but do not maintain intimate contacts for aspheric surfaces. Flexible tools conform to the surface, but lack smoothing. A rigid conformal (RC) lap using a visco-elastic non-Newtonian medium was developed. It conforms to the aspheric shape, yet maintains stability to provide natural smoothing.The second topic is a smoothing model for the RC lap. The smoothing naturally removes mid-to-high frequency errors while a large tool runs over the workpiece to remove low frequency errors efficiently. The CCOS process convergence rate can be significantly improved by predicting the smoothing effects. A parametric smoothing model was introduced and verified.The third topic is establishing a TIF model to represent measured TIFs. While the linear Preston's model works for most cases, non-linear removal behavior as the tool overhangs the workpiece edge introduces a difficulty in modeling. A parametric model for the edge TIFs was introduced and demonstrated. Various TIFs based on the model are provided as a library.The last topic is an enhanced process optimization technique. A non-sequential optimization technique using multiple TIFs was developed. Operating a CCOS with a small and well characterized TIF achieves excellent performance, but takes a long time. Sequential polishing runs using large and small tools can reduce this polishing time. The non-sequential approach performs multiple dwell time optimizations for the entire CCOS runs simultaneously. The actual runs will be sequential, but the optimization is comprehensive.

The purpose of this study is to develop an approach that considers fire as a load in the design of structures. Recent studies of the full-scale fire tests in Cardington, UK and the World Trade Centre collapse have shown that the behaviour of steel structures in fire when assembled into a frame differs from that measured or predicted by fire testing of individual structural elements, revealing the importance of accounting for realistic fire loads in the design of structures and the potential inadequacy of fire testing individual elements as employed by current building codes. Yet, there has been limited basic research and development to allow consideration of fire as a load in the analysis and design of structures. In response to this much needed work, this thesis develops an approach to include fire as a load in the analysis of a 2-bay by 2-storey structure when a semi-rigid connection is exposed to thermal loads typical of those that might be encountered during a real fire. The structural fire analysis is principally based on incorporating moment-rotation-temperature data for the connection, as found in archival literature, into a structural analysis software package developed at the University of Waterloo. The software employs a modified Displacement Method for analyzing structures, which involves the computation of stiffness reduction factors that represent the deterioration of strength of the structural elements as they are subjected to various loads. By modifying the moment-rotation-temperature data for a semi-rigid connection into a form recognized by the software, a fire load is simulated by incrementally elevating the temperature of the affected steel connection. In this way, a fragility analysis of the entire structure under fire load is conducted. A series of example calculations are presented for cases in which the semi-rigid connection is exposed to increasing temperatures of 20°C, 200°C, 400°C and 600°C. The analysis showed that as the connection is heated, it is weakened, and the steel structure undergoes a redistribution of moments from the heated connection to other non-heated elements within the framework, which is essentially a form of fire-resistance of the assembled structure that unassembled members in isolation do not have. The study also demonstrated that the experimental moment-rotation-temperature data reported in archival literature can be incorporated into the structural analysis, and that additional force-deformation data obtained from further experimental work or through finite-element analyses would allow the study to be extended to analyze the effects of fire loading on other structural elements of an assembled framework. To demonstrate the link between the predicted structural response at different temperatures and the development of a compartment fire, a fire modelling analysis is also performed.

During orthopaedic surgery, preoperative CT scans can be aligned to the patient to assist the guidance of surgical instruments and the placement of implants. Registration (i.e. alignment) can be accomplished in many ways: by registering implanted fiducial markers, by touching a probe to the bone surface, or by aligning intraoperative two dimensional flouro images with the the three dimensional CT data. These approaches have problems: They require exposure of the bone, subject the patient and surgeons to ionizing radiation, or do both. Ultrasound can also be used to register a preoperative CT scan to the patient. The ultrasound probe is tracked as it passes over the patient and the ultrasound images are aligned to the CT data. This method eliminates the problems of bone exposure and ionizing radiation, but is computationally more difficult because the ultrasound images contain incomplete and unclear bone surfaces. In this work, we compare three methods to register a set of ultrasound images to a CT scan: Iterated Closest Point, Mutual Information and a novel method Points-to-Image. The average Target Registration Error and speed of each method is presented along with a brief summary of their strengths and weaknesses. / Thesis (Master, Computing) -- Queen's University, 2009-01-22 04:21:22.569

Šiuolaikinių tiltų įstabios architektūrinės formos ir tiltų statybos vietos ne visada leidžia pritaikyti dažniausiai naudojamas konstrukcines schemas. Todėl inžinieriams tenka pasinaudoti retesniais, mažiau tyrinėtais tiltų konstrukciniais variantais. Pastaruoju metu pasaulyje, ypač Kinijoje, vėl pradėta naudoti kabamųjų tiltų atmaina – neskėtrieji kabamieji tiltai. Išaugęs tokių tiltų poreikis reikalauja išsamios neskėtriojo kabamojo tilto elgsenos ypatumų analizės. Nuodugniam šios konstrukcinės schemos analizės atlikimui suformuluojamas darbo tikslas – išnagrinėti neskėtriųjų tiltų pradinės analizės metodus, įvairių variantų vienpilonių neskėtriųjų tiltų elgseną veikiant statinei apkrovai. Šiam tikslui pasiekti keliami tokie uždaviniai: 1. Apžvelgti kabamųjų tiltų konstrukcijas, jų projektavimo bei elgsenos ypatumus. 2. Išanalizuoti kabamųjų tiltų analizės metodus, išskiriant neskėtriųjų tiltų skaičiavimo ypatumus. 3. Išanalizuoti vienpilonių neskėtriųjų plieno tiltų elgseną, veikiant simetrinei ir asimetrinei apkrovoms. 4. Kabamojo tilto pradinei formai stabilizuoti pritaikyti baigtinio lenkiamojo standžio elementus. 5. Parinkti neskėtriojo tilto racionalius komponuojamuosius parametrus ir įvertinti neskėtriųjų kabamųjų tiltų panaudojimo galimybes. Darbe taikomas kompiuterinis modeliavimas baigtinių elementų metodu, naudojantis MIDAS Civil programa. Apžvelgiami gauti rezultatai ir pateikiamos išvados bei pasiūlymai. / Wonderful shapes of modern bridges, especially pedestrian, and their construction sites not always let to adapt usual bridge structure. That’s why engineers have to use unusual and less researched structures. Recently in the world, especially in China, other suspended structure is being used – self-anchored suspension bridges. Recently grown popularity of these bridges requires comprehensive self-anchored bridge behavioral analysis. For an extensive analysis accomplishment the objective is stated – to examine initial analysis methods of self-anchored suspension bridges, behavior of various two-span self-anchored bridges subjected to static loading. To achieve this objective, following tasks are raised: 1. Review suspension bridge structures, their analysis and design peculiarities. 2. Analyze calculation methods of suspension bridges, including peculiarities of self-anchored bridge design. 3. Analyze behavior of steel two-span self-anchored suspension bridge subjected to symmetrical and asymmetrical loading. 4. Apply finite bending stiffness elements for main cables to stabilize primer shape. 5. Evaluate self-anchored suspension bridge technical-economic performance. Computer-aided design using finite element program MIDAS Civil is applied in this research. An overview of the results with conclusions and recommendations are presented.

Quasi-articulated objects, such as human beings, are among the most commonly seen objects in our daily lives. Extensive research have been dedicated to 3D shape reconstruction and motion analysis for this type of objects for decades. A major motivation is their wide applications, such as in entertainment, surveillance and health care. Most of existing studies relied on one or more regular video cameras. In recent years, commodity depth sensors have become more and more widely available. The geometric measurements delivered by the depth sensors provide significantly valuable information for these tasks. In this dissertation, we propose three algorithms for monocular pose estimation and shape reconstruction of quasi-articulated objects using a single commodity depth sensor. These three algorithms achieve shape reconstruction with increasing levels of granularity and personalization. We then further develop a method for highly detailed shape reconstruction based on our pose estimation techniques. Our first algorithm takes advantage of a motion database acquired with an active marker-based motion capture system. This method combines pose detection through nearest neighbor search with pose refinement via non-rigid point cloud registration. It is capable of accommodating different body sizes and achieves more than twice higher accuracy compared to a previous state of the art on a publicly available dataset. The above algorithm performs frame by frame estimation and therefore is less prone to tracking failure. Nonetheless, it does not guarantee temporal consistent of the both the skeletal structure and the shape and could be problematic for some applications. To address this problem, we develop a real-time model-based approach for quasi-articulated pose and 3D shape estimation based on Iterative Closest Point (ICP) principal with several novel constraints that are critical for monocular scenario. In this algorithm, we further propose a novel method for automatic body size estimation that enables its capability to accommodate different subjects. Due to the local search nature, the ICP-based method could be trapped to local minima in the case of some complex and fast motions. To address this issue, we explore the potential of using statistical model for soft point correspondences association. Towards this end, we propose a unified framework based on Gaussian Mixture Model for joint pose and shape estimation of quasi-articulated objects. This method achieves state-of-the-art performance on various publicly available datasets. Based on our pose estimation techniques, we then develop a novel framework that achieves highly detailed shape reconstruction by only requiring the user to move naturally in front of a single depth sensor. Our experiments demonstrate reconstructed shapes with rich geometric details for various subjects with different apparels. Last but not the least, we explore the applicability of our method on two real-world applications. First of all, we combine our ICP-base method with cloth simulation techniques for Virtual Try-on. Our system delivers the first promising 3D-based virtual clothing system. Secondly, we explore the possibility to extend our pose estimation algorithms to assist physical therapist to identify their patients’ movement dysfunctions that are related to injuries. Our preliminary experiments have demonstrated promising results by comparison with the gold standard active marker-based commercial system. Throughout the dissertation, we develop various state-of-the-art algorithms for pose estimation and shape reconstruction of quasi-articulated objects by leveraging the geometric information from depth sensors. We also demonstrate their great potentials for different real-world applications.

Computer applications can be described as largely rigid structures within which an information seeker must navigate in search of information - each screen, each transaction having underlying unique code. The larger the application, the higher the number of lines of code and the larger the size of the application executable. This study suggests an alternative pattern based approach, an approach driven by the information seeker. This alternative approach makes use of value embedded in intelligent patterns to assemble rules and logic constituents, numerous patterns aggregating to form a ‟virtual screen‟ based on the need of the information seeker. Once the information need is satisfied, the atomic rules and logic constituents dissipate and return to a base state. These same constituents are available, are reassembled and form the succeeding ‟virtual screen‟ to satisfy the following request. The pattern based approach makes use of multiple pattern ‟instances‟ to deliver functionality each pattern instance has a specific embedded value. Numbers of these patterns aggregate to drive the formation of a ‟virtual screen‟ built using patterns, each pattern referencing and associating (physical) atomic logic and spatial constituents. This is analogous to painting a picture using removable dots. The dots can be used to describe a fish, and then, once appreciation has been completed, the image is destroyed and the dots are returned to the palette. These same dots can later be reapplied to present the picture of a dog, if that is requested by the information seeker. In both pictures the same ‟dots‟ are applied and reused. The form of the fish and dog are retained as value embedded within the patterns, the dots are building blocks aligned using instructions within the patterns. This group classifies current solutions within the ‟Artefact-Pattern-Artefact‟ (APA) group and the pattern based approach within the ‟Pattern-Artefact-Pattern‟ (PAP) group. An overview and characteristics of each are discussed. The study concludes by presenting the results obtained when using a prototype developed using the PAP approach. / Thesis (Ph.D. (Information Technology))--North-West University, Vaal Triangle Campus, 2011

Computer applications can be described as largely rigid structures within which an information seeker must navigate in search of information - each screen, each transaction having underlying unique code. The larger the application, the higher the number of lines of code and the larger the size of the application executable. This study suggests an alternative pattern based approach, an approach driven by the information seeker. This alternative approach makes use of value embedded in intelligent patterns to assemble rules and logic constituents, numerous patterns aggregating to form a ‟virtual screen‟ based on the need of the information seeker. Once the information need is satisfied, the atomic rules and logic constituents dissipate and return to a base state. These same constituents are available, are reassembled and form the succeeding ‟virtual screen‟ to satisfy the following request. The pattern based approach makes use of multiple pattern ‟instances‟ to deliver functionality each pattern instance has a specific embedded value. Numbers of these patterns aggregate to drive the formation of a ‟virtual screen‟ built using patterns, each pattern referencing and associating (physical) atomic logic and spatial constituents. This is analogous to painting a picture using removable dots. The dots can be used to describe a fish, and then, once appreciation has been completed, the image is destroyed and the dots are returned to the palette. These same dots can later be reapplied to present the picture of a dog, if that is requested by the information seeker. In both pictures the same ‟dots‟ are applied and reused. The form of the fish and dog are retained as value embedded within the patterns, the dots are building blocks aligned using instructions within the patterns. This group classifies current solutions within the ‟Artefact-Pattern-Artefact‟ (APA) group and the pattern based approach within the ‟Pattern-Artefact-Pattern‟ (PAP) group. An overview and characteristics of each are discussed. The study concludes by presenting the results obtained when using a prototype developed using the PAP approach. / Thesis (Ph.D. (Information Technology))--North-West University, Vaal Triangle Campus, 2011