Department of Civil engineering

This paper examines and contrasts the feasibility of joint state and parameter estimation of noise-driven chaotic systems using the extended Kalman filter (EKF), ensemble Kalman filter (EnKF), and particle filter (PF). In particular, we consider the chaotic vibration of a noisy Duffing oscillator perturbed by combined harmonic and random inputs ensuing a transition probability density function (pdf) of motion which displays strongly non-Gaussian features. This system offers computational simplicity while exhibiting a kaleidoscope of dynamical behavior with a slight change of input and system parameters. An extensive numerical study is undertaken to contrast the performance of various nonlinear filtering algorithms with respect to sparsity of observational data and strength of model and measurement noise. In general, the performance of EnKF is better than PF for smaller ensemble size, while for larger ensembles PF outperforms EnKF. For moderate measurement noise and frequent measurement data, EKF is able to correctly track the dynamics of the system. However, EKF performance is unsatisfactory in the presence of sparse observational data or strong measurement noise.

Educational technology has obtained great importance over the last fifteen years. At present, the umbrella of educational technology incorporates multitudes of engaging online environments and fields. Learning analytics and Massive Open Online Courses (MOOCs) are two of the most relevant emerging topics in this domain. Since they are open to everyone at no cost, MOOCs excel in attracting numerous participants that can reach hundreds and hundreds of thousands. Experts from different disciplines have shown significant interest in MOOCs as the phenomenon has rapidly grown. In fact, MOOCs have been proven to scale education in disparate areas. Their benefits are crystallized in the improvement of educational outcomes, reduction of costs and accessibility expansion. Due to their unusual massiveness, the large datasets of MOOC platforms require advanced tools and methodologies for further examination. The key importance of learning analytics is reflected here. MOOCs offer diverse challeng...

A new efficient method for identification of the damping matrix of general linear dynamic systems is proposed. For a given frequency band, the proposed method estimates the equivalent reduced-order damping matrix of a general linear dynamical system, with the mass and stiffness matrices known a priori. Proper orthogonal decomposition (POD) method is used to represent an optimal reduced order model in the frequency range of interest. To mitigate the ill-conditioned nature of this inverse problem, Tikhonov regularisation is applied. The proposed methodology circumvents, or at least alleviates, the difficulties encountered in applying conventional modal analysis techniques in the high and mid frequency range.

Study of the unsteady aerodynamics of flapping airfoils has received a major boost in the recent past for its application in the field of MAV design. The present study investigates the unsteady flow-field over a flapping airfoil with asymmetric kinematics. Different asymmetry mechanisms are investigated for their lift enhancement capabilities during hover. Three asymmetries have been tried: amplitude, frequency and unsteady free-stream. Average aerodynamic loads are compared for all the cases. Flow field vortices are also compared. For the amplitude asymmetry case, pitch angles are varied between the strokes. Both normal and sinusoidal hover are considered. The normal hover case shows a significant increase in the average lift value compared to its sinusoidal counterpart. Subsequently, the frequency asymmetry mechanism has shown a significant increase in load for the sinusoidal hover case. Frequency asymmetry kinematics is achieved by using a faster stroke followed by a slower stroke. Depending on the level of asymmetry, a large amount of lift can be generated during the faster stroke. A third mechanism of sinusoidally varying oncoming flow with mean zero is also investigated. The flow-field is simulated with a Lagrangian particle based technique. In this algorithm, field property vorticity is represented by discrete particles. The flow-field is simulated at a Reynolds number around 3000 which is much higher than similar studies reported earlier. The Reynolds number range considered here is applicable to various man-made flapping devices like Micro Aerial Vehicles (MAVs). Crucial flow features like the dynamic stall vortex and its interaction with the trailing edge structures are studied for different asymmetry factors in the flow-field.

Wind loads acting on wind turbine blades are inherently random and are often modelled as a Gaussian process. However, studies carried out through real life wind data measurement shows that wind loads possess considerable amount of skewness and kurtosis, thereby making them non-Gaussian. This study focusses on developing load models that capture's the non-Gaussianity through a class of processes known as Laplace driven Moving Average (LMA). Measurements obtained from experiments carried out in a wind tunnel under gusty conditions are used for this load modelling. Subsequently, Response analysis is carried out to study the propogation of uncertainties into the response due to the random loading.

Study of the unsteady aerodynamics of flapping airfoils has received a major boost in the recent past for its application in the field of MAV design. The present study investigates the unsteady flow-field over a flapping airfoil with asymmetric kinematics. Different asymmetry mechanisms are investigated for their lift enhancement capabilities during hover. Three asymmetries have been tried: amplitude, frequency and unsteady free-stream. Average aerodynamic loads are compared for all the cases. Flow field vortices are also compared. For the amplitude asymmetry case, pitch angles are varied between the strokes. Both normal and sinusoidal hover are considered. The normal hover case shows a significant increase in the average lift value compared to its sinusoidal counterpart. Subsequently, the frequency asymmetry mechanism has shown a significant increase in load for the sinusoidal hover case. Frequency asymmetry kinematics is achieved by using a faster stroke followed by a slower stroke. Depending on the level of asymmetry, a large amount of lift can be generated during the faster stroke. A third mechanism of sinusoidally varying oncoming flow with mean zero is also investigated. The flow-field is simulated with a Lagrangian particle based technique. In this algorithm, field property vorticity is represented by discrete particles. The flow-field is simulated at a Reynolds number around 3000 which is much higher than similar studies reported earlier. The Reynolds number range considered here is applicable to various man-made flapping devices like Micro Aerial Vehicles (MAVs). Crucial flow features like the dynamic stall vortex and its interaction with the trailing edge structures are studied for different asymmetry factors in the flow-field.

Researchers have been questioning if traffic microsimulation tools can be used for road safety evaluations. This thesis examines if these tools have the potential to predict conflicts between right-turning vehicles and through cyclists at signalized intersections. Moreover, this thesis evaluates if calibrating these models to describe the driving behaviour at signalized intersections significantly improves the conflicts' prediction. It was found that VISSIM has the potential to predict traffic conflicts of interest. In particular, a moderate correlation was found between real conflicts and simulated conflicts of the default models (= 0.525). Calibrating the model for travel time improved the correlation between real conflicts and simulated conflicts (= 0.618). However, a one-way ANOVA test indicated that the improvement caused by travel time calibration was not significant. It was also found that VISSIM's prediction accuracy is expected to decrease as either the cyclists' volume or the product of cyclists' volume and right-turning vehicles' volume increase.

Researchers have been questioning if traffic microsimulation tools can be used for road safety evaluations. This study examines the use traffic microsimulation to predict conflicts between right-turning vehicles and through cyclists at signalized intersections. Moreover, this study evaluates if calibrating these models to describe the driving behavior at signalized intersection significantly improves the conflicts prediction. It was found that VISSIM has the potential to predict traffic conflicts of interest. In particular, a moderate correlation was found between real conflicts and simulated conflicts of the default models (? = 0.525). A strong correlation was found between real conflicts and calibrated models’ simulated conflicts (? = 0.618). However, a one-way ANOVA test indicated that travel time calibration did not significantly affect VISSIM’s conflicts prediction accuracy. It was also found that VISSIM’s prediction accuracy is expected to decrease as either the cyclists’ volu...

The objective of this paper is to present a framework for the evaluation of traffic safety improvements on rural highways based on the existing process of the Ministry of Transportation of Ontario (MTO). The framework includes four steps to identify hazardous locations and determine the most feasible improvements. The framework was applied to a 2.2 km segment on Highway 17 (Ontario, Canada) to illustrate how the framework might be implemented in practice. The first step is defining the highway section to be studied. This section is usually a segment that was constructed in the same contract, and its surface conditions require major maintenance. The evaluation of traffic safety on sections that are undergoing major pavement rehabilitation will reduce the overall cost of road maintenance. The second step is to collect and analyze collision data, along with traffic and geometric data. The purpose of this step is to compare the actual number of collisions on the section with the expected long-run mean value and identify the causes of collisions. Based on this analysis, the third step identifies the possible improvements that would eliminate or minimize the number of collisions. These improvements can be as simple as signing improvement or as complex as a major realignment. Finally, these improvements are evaluated economically and environmentally. For this study, several sections of the Ministry of Transportation of Ontario, other ministries and levels of government, and interest groups participated in the evaluation process. A refined MTO process, currently being considered for implementation, is briefly described along with a discussion of its key features.

The effect of combining horizontal and vertical curves on operational conditions has been the subject of research over the last few years. A number of studies have reported that combining horizontal curves with crest and sag vertical curves would influence the curvature appearance of such combinations. According to these studies, drivers could misperceive the curvature of a horizontal curve when combined with a vertical curve, and this might result in negative operational effects. These negative effects would most notably be in the form of an erroneous driver's speed choice. This study presents a driving simulation experiment that was planned and conducted to examine the effect of driver's misperception of horizontal curvature on driver's speed behavior. The simulation data were analyzed statistically and provided support for the hypothesis that driver's misperception of horizontal curvature affects their choice of speed. The effects of several geometric parameters on speed were also examined including curve radius, algebraic difference of vertical grades, rate of vertical curvature, turning direction, superelevation rate, and sight distance.

Several models have been developed to determine the minimum passing sight distance required for safe and efficient operation on two-lane highways. The American Association of State Highway and Transportation Officials has developed a model assuming that once the driver begins a pass, he/she has no opportunity but to complete it. This assumption is believed to result in exaggerated passing sight distance requirements. Considerably shorter passing sight distance values are presented in the Manual of Uniform Traffic Control Devices and are used as the marking standards in Canada and the U.S.A. More appropriate models have been developed considering the driver's opportunity to abort the pass, and are based on a critical sight distance which produces the same factor of safety whether the pass is completed or aborted. However, these models need to be revised to determine the passing sight distance requirements more accurately and to closely match field observations. In this paper, a revised model for determining the minimum required passing sight distance was developed, based on the concept of critical sight distance and considering the kinematic interaction between the passing, passed, and opposing vehicles. The results of the revised model were compared with field data and showed that the revised model simulates the passing manoeuvre better than the currently-available models which are either too conservative or too liberal. The results showed that the passing sight distance requirements recommended in the Manual of Uniform Traffic Control Devices are sufficient at low design speeds (5&60 k.p.h.) and for manoeuvres involving passenger cars only. For higher design speeds, the Manual of Uniform Traffic Control Devices standards are less than the passing sight distance required for safe and comfortable passes. The deficiency was found to increase with the increase in design speed, and reaches about 36% at a 120-k.p.h. design speed. Based on these results, major revisions to the current Manual of Uniform Traffic Control Devices marking standards are recommended.