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Abstract Most of literature and studies on prediction of exchange rate focus on main industrial countries with few discussions on the exchange rate of the developing countries. For model residual differences can be found in a linear model, so the linear model will adjust to find equilibrium at a fixed speed. However, it is difficult for the linear model to capture the character of dynamic adjustment behavior if a non-linear adjustment relationship exists (Sarno, 2002). Moreover, in case the trading costs exist in the foreign exchange market or the technical analysis is widely used among traders, then the deviations from equilibrium exchange rate may present a non-linear adjustment trend. In view of this, this study employed the STAR (smooth transition autoregression) model developed by Granger and Terasvirta (1993) to discuss the dynamic adjustment process of the deviations from UIP in the seven countries in Latin America. In most of the experimental studies conducted in the past, it was found difficult to establish the assumptions of uncovered interest parity (UIP). Therefore, this study is aimed to verify the experimental studies on UIP in the Latin America under the non-linear framework by means of non-linear model analysis.

The purpose of the current research was to examine how a novel balance task is learnt by individuals with a mature neurological system, and to investigate the responses of experienced hand balancers to mechanical and sensory perturbations. Balance in each posture was assessed by various techniques, including: traditional measures of centre of pressure, nonlinear time series analysis of centre of pressure, estimates of feedback time delay from cross correlations and delayed regression models, and calculation of small, medium, and large movement corrections. Data from this study suggests that the best balance metric for distinguishing between each of the balance conditions was the traditional balance measure of sway velocity. However, sway velocity cannot provide any further information on the underlying process of balance. Nonlinear measures of balance offer insight into the underlying deterministic processes that control balance, offering measures of system determinism, complexity, and predictability. Assessments of feedback time delay and movement corrections provide both an insight into the control of posture and help distinguish one condition from another. Both feedback time delay and movement corrections and magnitudes may be used simultaneously to delve further into the control of posture. Delayed regression models seem to be an appropriate and useful tool for estimating feedback time delays during balance. Findings support the use of the third term in the adapted regression model as a means of estimating the effect of passive stiffness on feedback time delay. Generally, with increased duration in handstand subjects displayed reduced sway as measured by traditional measures of balance. A more marked change in nonlinear measures of balance can be seen, with quicker reductions in variance for some nonlinear measures of balance than in the traditional measures. It may be that more pronounced changes in nonlinear measures represent changes in the subjects underlying process of postural control, whereas less pronounced changes in traditional measures relate more to their general ability or performance in the balance task.

The purpose of this study is to analyze reinforced concrete frames subjected to abnormal loads. Structures are rarely subjected to abnormal loads, however, when they are subjected to them, it can lead to a progressive collapse. The World Trade Centers in New York City and the Alfred P. Murrah building in Oklahoma City are examples of structures being deliberately subjected to abnormal loads. Structures can also experience unintentional abnormal loading. Examples include the Ronan Point apartment building in Canning Town, England and Husky Stadium at the University of Washington. Consequently, many analysis and design standards now explicitly account for abnormal loads and try to mitigate their effects. This study presents the development of a nonlinear computer analysis program for reinforced concrete frames. The method of analysis involves discretizing a two dimensional reinforced concrete frame into a series of beam-column elements. The element is linear-elastic, however, its end-sections model nonlinear behaviour of a total member by a series of springs. The springs represent the post-elastic stiffness of the end-sections. The post-elastic stiffness of a member-section is obtained from a post-elastic force-deformation response, which is first obtained by performing sectional analysis on a reinforced concrete section using a public domain computer program. The post-elastic force-deformation responses are modeled as either bilinear or trilinear. So-called stiffness degradation factors, which are defined as the ratio of elastic to elastic plus post-elastic deformation of a member-section, are used in modifying the elastic stiffness coefficients in the element stiffness matrix to account for the nonlinear behaviour. Once a reinforced concrete frame enters the post-elastic range of response the analysis procedure becomes incremental. The stiffness degradation factors are calculated at each load increment and the degree of post-elastic stiffness degradation is progressively tracked throughout the load history. The program also has the capability of performing a progressive collapse analysis whereby debris loads caused by falling members are calculated and applied to the structure. A series of example problems are presented to demonstrate the computer analysis program.

The purpose of this study is to analyze reinforced concrete frames subjected to abnormal loads. Structures are rarely subjected to abnormal loads, however, when they are subjected to them, it can lead to a progressive collapse. The World Trade Centers in New York City and the Alfred P. Murrah building in Oklahoma City are examples of structures being deliberately subjected to abnormal loads. Structures can also experience unintentional abnormal loading. Examples include the Ronan Point apartment building in Canning Town, England and Husky Stadium at the University of Washington. Consequently, many analysis and design standards now explicitly account for abnormal loads and try to mitigate their effects. This study presents the development of a nonlinear computer analysis program for reinforced concrete frames. The method of analysis involves discretizing a two dimensional reinforced concrete frame into a series of beam-column elements. The element is linear-elastic, however, its end-sections model nonlinear behaviour of a total member by a series of springs. The springs represent the post-elastic stiffness of the end-sections. The post-elastic stiffness of a member-section is obtained from a post-elastic force-deformation response, which is first obtained by performing sectional analysis on a reinforced concrete section using a public domain computer program. The post-elastic force-deformation responses are modeled as either bilinear or trilinear. So-called stiffness degradation factors, which are defined as the ratio of elastic to elastic plus post-elastic deformation of a member-section, are used in modifying the elastic stiffness coefficients in the element stiffness matrix to account for the nonlinear behaviour. Once a reinforced concrete frame enters the post-elastic range of response the analysis procedure becomes incremental. The stiffness degradation factors are calculated at each load increment and the degree of post-elastic stiffness degradation is progressively tracked throughout the load history. The program also has the capability of performing a progressive collapse analysis whereby debris loads caused by falling members are calculated and applied to the structure. A series of example problems are presented to demonstrate the computer analysis program.

Αντικείμενο της παρούσας διατριβής αποτελεί η ανάλυση της συμπεριφοράς αξονικά φορτιζόμενου πασσάλου, η οποία μπορεί να οδηγήσει σε απώλεια φέρουσας ικανότητας. Συγκεκριμένα εξετάζεται η στατική δυσκαμψία του πασσάλου για τις περιπτώσεις ομοιογενούς και ανομοιογενούς εδάφους. Για την επίλυση του προβλήματος αναπτύχθηκε απλή αναλυτική ενεργειακή μέθοδος, η οποία βασίζεται στη θεωρία Winkler και στη χρήση συνάρτησης σχήματος, η οποία περιγράφει αξιόπιστα τις μετατοπίσεις κατά μήκος του πασσάλου. Το έδαφος γύρω από τον πάσσαλο προσομοιώνεται με κατακόρυφα γραμμικά ή μη ελατήρια τύπου Winkler, τα οποία εφαρμόζονται στην παρειά του πασσάλου αλλά και στη βάση του. Με επιλογή κατάλληλης συνάρτησης σχήματος και καμπυλών «τ-w» και «Pb-wb» και μετά από επαναληπτική διαδικασία εφαρμογής της μεθόδου, επιτυγχάνεται με ικανοποιητική ακρίβεια η τιμή της δυσκαμψίας για κατακόρυφη μετακίνηση στην κεφαλή του πασσάλου. / The present thesis deals with the analysis of the axial static response of a single pile, which may lead to bearing capacity loss. Specifically, the static stiffness of the pile located both in homogeneous and in inhomogeneous soil, is studied. For the analysis a simple energy method is employed, based on Winkler theory and on use of a shape function which represents reliably the deflected shape of the pile. The soil around the pile is simulated with vertical linear or nonlinear Winkler springs, applied to the sidewall of the pile and its base. Realistic predictions can be achieved for the value of stiffness of axially loaded piles, after iterative application of the method, by using the appropriate shape functions, “ τ-w “ and “Pb-wb” curves.

Dynamics in locomotion is highly useful, as can be seen in animals and is becomingapparent in robots. For instance, chimpanzees are dynamic climbers that canreach virtually any part of a tree and even move to neighboring trees, while sloths arequasistatic climbers confined only to a few branches. Although dynamic maneuversare undoubtedly beneficial, only a few engineered systems use them, most of whichlocomote horizontally. This is because the design and control are often extremelycomplicated.This thesis explores a family of dynamic climbing robots which extend roboticdynamic legged locomotion from horizontal motions such as walking, hopping, andrunning, to vertical motions such as leaping maneuvers. The motion of these dynamicrobots resembles the motion of an athlete jumping and climbing inside achute. Whereas this environment might be an unnavigable obstacle for a slow, quasistaticclimber, it is an invaluable source of reaction forces for a dynamic climber.The mechanisms described here achieve dynamic, vertical motions while retainingsimplicity in design and control.The first mechanism called DSAC, for Dynamic Single Actuated Climber, comprisesonly two links connected by a single oscillating actuator. This simple, openlooposcillation, propels the robot stably between two vertical walls. By rotating theaxis of revolution of the single actuator by 90 degrees, we also developed a simplerrobot that can be easily miniaturized and can be used to climb inside tubes.The DTAR, for Dynamic Tube Ascending Robot, uses a single continuously rotatingmotor, unlike the oscillating DSAC motor. This continuous rotation even furthersimplifies and enables the miniaturization of the robot to enable robust climbinginside small tubes. The last mechanism explored in this thesis is the ParkourBot,which sacrifices some of the simplicity shown in the first two mechanism in favorof efficiency and more versatile climbing. This mechanism comprises two efficientspringy legs connected to a body.We use this family of dynamic climbers to explore a minimalist approach to locomotion.We first analyze the open-loop stability characteristics of all three mechanisms.We show how an open-loop, sensorless control, such as the fixed oscillationof the DSAC’s leg can converge to a stable orbit. We also show that a change inthe mechanism’s parameters not only changes the stability of the system but alsochanges the climbing pattern from a symmetric climb to a limping, non-symmetricclimb. Corresponding analyses are presented for the DTAR and ParkourBot mechanisms.We finally show how the open-loop behavior can be used to traverse morecomplex terrains by incrementally adding feedback. We are able to achieve climbinginside a chute with wall width changes without the need for precise and fast sensingand control.

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This thesis presents the results of an investigation of a multiple degree of freedom (MDOF) structure with hyperelastic bracing using nonlinear and incremental dynamic analysis. New analytical software is implemented in the investigation of the structure, and the study seeks to investigate the effectiveness of hyperelastic bracing as a seismic protection device. Hyperelastic braces incorporate a new idea of a nonlinear elastic material that gains stiffness as the brace deforms. Structural behaviors of particular concern for an MDOF frame are stability, residual displacement, base shear, and dispersion. The structure is analyzed under two ground motion records of varying content, and for two separate P-Delta cases of varying severity. Two sets of hyperelastic braces are investigated for their influence under the two ground motions and two P-Delta cases. Each scenario is analyzed using nonlinear dynamic analyses to investigate the response histories, and Incremental Dynamic Analysis (IDA) to investigate dispersion and the behavior of specific response measures as ground motion intensity increases. IDA curves are created for interstory drift and base shear for comparison between the two response measures. The research shows that the inclusion of hyperelastic braces in the MDOF frame improves the overall stability of the structure and reduces the amount of dispersion and residual displacement. The hyperelastic braces are shown to give positive performance characteristics while not detrimentally increasing system forces under regular service loads. The results highlight the benefit of the unique stiffening properties of hyperelastic braces as a seismic protection device. / Master of Science