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Solutions to selected exercises: an introduction to database systems
No full textThe purpose of this guide is to assist the student of an introductory course in database system in conjunction with the author’s text Introduction to Database Systems. It is suggested that the student try the exercises given a the end of the chapters before consulting the solutions given here and compare their the solutions.
The organization of this guide follows the suggested plan diagrammed in the preface of the text. Solutions for selected end of chapter exercises are given. The exercises in some of the chapters are of a general nature and their solutions are not included. The chapters on File organization and Higher order normal forms would not be covered in many undergraduate syllabus: and Chapters 8 and 9, are often considered obsolete, and not covered in these courses. Hence the solution to the exercises in these chapters are not provided
A Comparison of 1D Beam-element and 3D Solid-element based Modelling Approaches based on a Developed Tool for the Nonlinear Analysis of Reinforced Concrete Structural Components
Get PDFNonlinear material models are needed for the capacity analysis of structural components. Often, 1D-beam element-based models are preferred over more sophisticated solid element-based modeling approaches due to their efficiency. However, their reliance on uniaxial material representations often overlooks the crucial influence of shear stresses, potentially leading to inaccuracies in predicting structural responses. In response, this study introduces a novel approach by integrating a multi-axial 3D concrete model within a 1D finite element framework, effectively capturing the effects of shear stresses. The proposed multi-axial elasto-plastic concrete model offers a comprehensive representation of concrete behavior under both tension and compression, thus enhancing the predictive capabilities of the analysis. By adopting a 1D beam-type finite element formulation, the research enables a detailed examination of shear wall behavior under lateral loading conditions. The main purpose of the thesis is to validate the developed finite element analysis tool which employs a sophisticated 3D concrete material model. The inelastic material behaviour of steel reinforcements bars has also been considered in the analysis. For the beam-type finite element, a 2-node formulation was adopted based on the Timoshenko theory so that the shear deformation effects are also considered in the analysis. For the modelling of the concrete bulk with 3D material model, the 8-node solid element with 6-degreesof-freedom per node including the nodal rotations was adopted. The numerical formulation is then used for pushover analysis of beams and shear walls and compared with experimental results from literature for validation purposes. Five different structural components are tested. Validation efforts include comparisons with experimental data from existing literature and alternative modelling approaches. Parametric studies are conducted by changing the span sizes of the structural components
Exploring my Musicality as a New Music Therapist: A Heuristic Self-Inquiry
Get PDFIt is important for music therapists to have musical self-awareness as it helps to ensure that they are not inadvertently imposing their pre-conceived personal and cultural notions of music aesthetics and musicality onto their clients. This research provided me with an opportunity to explore my current beliefs and assumptions about musicality and reflect upon how these might impact my work as a newly certified music therapist. Therefore, purpose of this heuristic self-inquiry was to reveal and examine assumptions that I hold about the concept of musicality and explore how these assumptions may inform my music therapy practice moving forward. As my family members’ musicianship has influenced my understanding of my own musicality and what it means to be musical at large, I engaged in an experiential self-inquiry process wherein I used free improvisations and reflexive journaling to explore how I have reacted and responded to three family members within the context of our musical relationships and past musical interactions that we shared. This resulted in four narrative summaries along with a cross case analysis that revealed three overarching themes: musician self-concept, musical traumas, and newly revealed assumptions and biases on musicality. A creative synthesis in the form of a sound collage served as a representation of the personal and tacit dimensions of this research process. Limitations of the study along with potential implications for others’ clinical practice and future research are also presented
Real Time Control of a Weed Removal Rover Through Visual Servoing
Get PDFThe gardening industry is a multi-billion-dollar enterprise, and currently lacks an autonomous system for removing weeds from an arbitrary garden. The Mobile Weed Remover (MWR) project in the Advanced Mechatronics and Robotics Lab at Concordia seeks to fill this void.
In this thesis, a great amount of re-design work has been carried out to improve the design of both mechanical and electrical systems of the second generation of MWR to make it functional. The mathematical models of MWR are built including the “ideal modeling” and “discrete modeling”. The simulation of the built models is carried out in Matlab/Simulink to investigate the dynamics of the robot. The control algorithm is designed including forward-backward position correction and error direction and handling. The designed controller is integrated with improved MWR robots and the real time control system is implemented in the on-board computer of the robots. The designed robot uses a camera in order to identify, seek out, and destroy weeds, which enables it to operate in an arbitrary garden. In order to target the roots of the weed, the MWR requires a positioning system that can guide the rover to the desired position, which should be able to take the cues from the visual system. The research in this thesis seeks to adapt a control algorithm to the MWR and enable it to approach a target.
Simulation was conducted to validate the effectiveness of the developed control algorithm. A simple mono-chrome target was used to represent the dandelion in the real time control tests. The experimental results further verify that the control system was operational and deliver satisfactory results
Do Children with Higher Levels of Sport Specialization Perform Fundamental Movement Skills Better than Children with Lower Specialization Scores?
Get PDFIntroduction: To assess the degree of sport specialization of a children, there is the newly developed 4-point scale [24]. This tool has been used to observe the correlation between sport specialization levels and injury risk. The Child-Focused Injury Risk Screening Tool (ChildFIRST) is a process-based tool assessing 10 skills to evaluate movement competence of the lower extremity in children aged 8 to 12 years old. Purpose: The purpose of this study is to assess the relationship between the participants’ level of sport specialization and their movement competence, scores they receive on the ChildFIRST. Methods: In this cross-sectional study, 70 participants (34 hockey players and 36 figure skaters), 8 to 12 years old, took part in a survey assessing their sport specialization level and were evaluated using the ChildFIRST tool. We analyzed the data using correlations, One-Way ANOVA, Kruskal-Wallis, Mann-Whitney U and descriptive statistics. Results: This study found that older athletes were more specialized and performed better on the ChildFIRST. However, it did not find a correlation between specialization level and ChildFIRST scores. When comparing the hockey to the figure skating group using non-parametric tests, we found that specialization levels and ChildFIRST scores are both significantly higher in the figure skating groups. Conclusion: These results suggests that in children aged 8 to 12 years old, there is no relationship between specializing early and movement competence in this study. They do however demonstrate that the figure skating group, across all ages, are more specialized and better at movement competence (performing better on lower limb motion and alignment movements)
Detection, Isolation, and Estimation of Cyber-Attacks in Presence of Faults in Cyber-Physical Systems
Get PDFThe security of Cyber-Physical Systems (CPS) has been the center of attention in the past decades. Developing methodologies to detect or estimate cyber-attacks on sensor measurements
and actuator inputs is essential for ensuring the safe and reliable performance of these interconnected systems of systems. Considering the stealthy nature of cyber-attacks, combined with potential faults, additional challenges emerge, which this thesis addresses through the lens of control theory.
In control theory, several methodologies have addressed the decoupling of unknown inputs, such as faults and disturbances. However, the simultaneous presence of faults and cyber-attacks
presents challenges that are not fully developed in the context of CPS. The first part of this thesis proposes a methodology, consisting of the construction of two plant-side monitoring filters to detect and isolate faults and cyber-attacks including covert and zero dynamic attacks. The findings are supported through analytical and simulation studies.
As the second challenge, a multi-rate approach is employed to estimate actuator cyber-attacks in the presence of sensors and actuators faults in CPS. A plant-side fault monitoring filter is
augmented with the physical system, and its residual, along with the plant’s outputs, is sent to C&C with a specified mechanism. Cyber-attacks are isolated from faults through the received
information in the C&C and a secondary observer. Consequently, a delayed Unknown Input Observer (UIO) is constructed to estimate the actuator cyber-attacks. The effectiveness of the proposed
methodology is evaluated through numerical case studies
Synergetic Wastewater Treatment: Implementing Annamox Enhanced Wastewater in Closed Loop Pressure Retarded Osmosis for Sustainable Energy Generation
Get PDFExploring the symbiotic potential of wastewater treatment and sustainable energy generation, this research integrates an Anammox (Anaerobic Ammonium Oxidation) reactor with Pressure Retarded Osmosis (PRO). The investigation considers three diverse feed solutions: Deionized (DI) water, synthetic water, and a composite of synthetic water with real mine wastewater from gold mines. The study assesses the nitrogen removal efficiency in the Anammox reactor, accounting for the distinctive compositions of each feed solution. Concurrently, the power output, and overall performance of the PRO system are analyzed using the Anammox reactor effluent as the feed solution.
DI water provides a baseline for comparison, synthetic water replicates-controlled conditions, and the inclusion of mine wastewater introduces real-world complexities. The present study critically examines the chemical interactions occurring within an integrated system, focusing on the observable impact of trace elements present in gold mine wastewater on both biological and osmotic processes.
The research provides valuable insights into the interaction between biological nitrogen removal and osmotic power generation across varied wastewater matrices. Results highlight the versatility of the proposed methodology, underscoring its practical significance for sustainable energy production in mining environments.
Initially for experiments on lab-scale PRO setup, solutions of NaCl, KCl, (NH4)2CO3 and MgCl2 were used as the draw solutions. Results from this exploration offer valuable considerations for wastewater treatment and energy production in gold mining operations, highlighting the potential for sustainable practices in resource-intensive industries. After examining different draw solutions, synthetic water and composite of synthetic water with real mine tailing water were tested with 3M (NH4)2CO3 as the draw solution which produced the average power density of 11.0 ± 0.5 W⁄m2 and fouling was observed within the timespan. Results demonstrated promising power generation capabilities, with significant reductions in ion concentrations in the permeate, indicating the effectiveness of the PRO process. Recommendations for future research include comprehensive techno-economic analyses, exploration of advanced membrane technologies, and integration of other bioremediation techniques to enhance pollutant removal and system performance. Overall, the integration of Annamox-PRO represents a promising approach towards enhancing sustainability, energy efficiency, and environmental stewardship in industrial settings, particularly in challenging environments like mining operations
Cyber-Attack Detection Methodologies for Cyber-Physical Systems: A System Theoretic Approach
Get PDFCyber-physical systems (CPS) are integral to critical infrastructures such as power networks, transportation systems, and water treatment networks. Despite the advancements in developing more secure CPS and monitoring systems, the number of successfully executed cyber-attacks in CPS has increased over the past decade. The mentioned cyber-attacks, which can make CPS unstable, are performed by intelligent adversaries who try to maintain their malicious attacks undetected. This thesis addresses several crucial challenges related to cyber-attacks in CPS and multi-agent systems (MAS).
The first part of the thesis focuses on simultaneous cyber-attacks and fault detection and isolation (CAFDI) in centralized and large-scale interconnected CPS. Proposed methodologies include centralized and distributed CAFDI approaches, incorporating two filters and an unknown input observer (UIO)-based detector to identify various deception attacks such as covert, zero dynamics, and replay attacks. The effectiveness of the distributed CAFDI approach is demonstrated through a hardware-in-the-loop (HIL) simulation of a four-area power network system.
The second part studies stealthy cyber-attacks in CPS, particularly zero dynamics, covert, and controllable attacks. Conditions for executing these attacks are derived from CPS Markov parameters and the system observability matrix. Dynamic coding schemes are proposed as countermeasures, increasing the number of actuators needed to execute cyber-attacks.
In the third part, zero dynamics and undetectable cyber-attacks in linear and nonlinear CPS are explored. A new security metric, security effort (SE), is introduced to determine the minimum number of secured actuators and sensors required to prevent such attacks in linear CPS. For nonlinear CPS, the study uses Koopman operator theory and the extended dynamic mode decomposition (EDMD) algorithm to create a finite-dimensional linear representation of the system to identify critical sensor measurements that need securing to prevent zero dynamics and covert attacks.
The fourth part addresses privacy-preserving consensus control, controllability cyber-attacks, undetectable cyber-attacks, and detection methodologies in MAS. A distributed transformation-based consensus control method is developed to protect agent privacy from eavesdroppers. Conditions for adversaries to control the MAS network by attacking a few agents are explored, defining these as controllability cyber-attacks. Undetectable cyber-attacks in MAS are defined and an event-triggered detection module to detect such attacks is proposed
Performance of GFRP bars for reinforced concrete beams under fatigue loading
Get PDFStructural components are susceptible to different types of loading, such as monotonic and cyclic loadings, etc. Fatigue loading is cyclic in nature and falls into two general categories: low-cyclic fatigue and high-cyclic fatigue. Glass fibre-reinforced polymer (GFRP) bars are suitable replacements for steel reinforcement rebars due to their corrosion-resistant characteristics. This characteristic warrants an extended service life for GFRP RC structures. The research investigates the fatigue performance of ribbed GFRP bars in concrete, which is crucial due to the growing use of GFRP as a substitute for traditional steel reinforcements. An experimental program was carefully planned to evaluate the fatigue life of ribbed GFRP bars within concrete beams, including factors such as concrete strength and the degrees of fatigue stress applied. An innovative displacement-controlled testing technique was devised to address the limitations of conventional force-controlled fatigue testing methods. The results demonstrate that ribbed GFRP bars may withstand up to 2 million cycles of fatigue stress, exceeding current code standards and questioning previous empirical data. This research also includes the fatigue characteristics of ribbed GFRP bars during tension-tension fatigue through a detailed review and innovative experiments. The experimental program included the fatigue, the fatigue life and the behaviour of ribbed GFRP bars, classifying them according to the testing protocol. Low-frequency fatigue testing is between 0.03 and 0.04 Hz, and fatigue tests are under higher frequency fatigue testing at 4 Hz. This research identified an optimal gripping mechanism for conducting fatigue tests on GFRP bars and evaluated the feasibility of using conventional universal testing machines for fatigue life assessment, commonly found in many structural laboratories. In addition, the impact of influential factors such as stress ratio is examined through a testing program. Finally, the study expands to present a simplified model based on the Sendeckyj model, but it utilizes a normal distribution to forecast the fatigue life of FRP-RC elements under repeated loading situations. This novel method is used to analyze fatigue data for GFRP, CFRP, and BFRP materials, allowing for the creation of S-N-P curves to be simplified with accurate estimations
Business Analytics Research in Public Health Communication: Exploring Opportunities and Identifying Threats
No full textThis thesis adopts a business analytics approach by merging data-driven and theory-driven approaches to demonstrate new opportunities for addressing public health issues such as vaccine hesitancy and health crisis management. It also examines the threat of selective sharing on social media exacerbating polarization and vaccine hesitancy.
The first essay tackles vaccine hesitancy by quantitatively analyzing eight years of data from the U.S. Vaccine Adverse Event Reporting System. This study addresses vaccine safety concerns by highlighting the non-severity of reported adverse events. Cognitive biases have significant roles in connecting such concerns to vaccine hesitancy. This essay identifies and categorizes fifteen cognitive biases influencing individuals’ vaccine decision-making. These findings underscore the importance of utilizing public data sources to mitigate vaccine safety concerns and inform public health communications strategies to counteract cognitive biases influencing vaccine hesitancy.
In two studies, the second essay delves into the role of social media in managing health crises, proposing the Social Media Health Crisis Management (SMHCM) model. By analyzing Canadian authorities’ use of Twitter (now X) during the COVID-19 pandemic for 13 months, study 1 demonstrates how authorities can facilitate shared situational awareness among citizens by disseminating declarative, procedural, and strategic knowledge. In Study 2, the SMHCM model proposes that authorities must publish posts containing declarative, procedural, and strategic knowledge to satisfy citizens’ informational needs and propagate emotional support content to cover their emotional needs during crises, increasing user engagement. The SMHCM model fills a knowledge gap by explaining how authorities can use social media to manage health crises, offering insights into effective health crisis communication strategies.
The third essay explores confirmation bias-induced selective sharing among social media users engaged in vaccine discourse, revealing how selective sharing contributes to polarization. This essay identifies pronounced confirmation bias by analyzing over 6.6 million posts from prominent vaccine discourse participants on Twitter. It also examines the interaction dynamics between vaccine stance groups (anti-vaccine, pro-vaccine, and libertarian). Its findings advance our understanding of confirmation bias-induced selective sharing in the context of vaccine hesitancy and highlight the complex challenges of countering polarized opinions and fostering constructive dialogue on social media