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Computational modeling of wind flow and wind-induced loads on low buildings
Get PDFMoving towards a new era where structural engineering applications will rely more on Computational Fluid Dynamics as means to evaluate wind related characteristics, this thesis demonstrates a novel computational technique to model wind flow and wind-induced structural loads. During the last decades there have been continuous efforts in modelling efficiently turbulent flows by the practice and scientific community. Various methodologies have been discussed in the literature, but their applicability for structural design remains problematic, thus wind design standards and codes of practice hesitate to adopt computational procedures for structural loads. Therefore, a new tool that serves the engineering needs while respecting the scientific requirements has been developed.
The so-called Dynamic Terrain method utilizes velocity time series extracted from the Concordia Wind Tunnel as inlet conditions. A first target achieved was to model accurately the energy of the fluctuations of turbulence scales that are smaller than the building characteristic dimensions. This accomplishment covers a research gap in the state-of-the-art identified during a comprehensive review study. Another achievement is the ability of the method to model various exposure conditions, in addition to the characteristic standard open, suburban and urban exposures. Quasi-steady conditions are assumed for the inlet time series as to respect physical aspects such as the divergence-free criteria and numerical stability. The final pressure time series are extracted by filtering the numerical data to account for the inherent discontinuity of the inlet conditions and their propagation in the computational domain.
With this engineering tool, modeling of wind flow and peak pressures on building envelopes become possible via simple procedures and advantageous techniques, compared with similar approaches currently available. Validation of wind flow and pressure characteristics are presented for various structural applications. Mean, std and peak pressures have been validated for loads on low-rise buildings based on experiments from TPU, NIST and the Concordia Wind Tunnel. The accuracy is within acceptable margins established by comparisons among the experimental results from respective wind tunnel facilities. The tool is incorporated in an open database, where experimental data from the Concordia Wind Tunnel and OpenFOAM libraries are included for free usage by practitioners and scientific groups
Developing a Framework for Supplier Evaluation and Development: Implementation in a Manufacturing Company.
No full textThis thesis introduces a comprehensive model for supplier evaluation and development, specifically tailored to a mid-sized manufacturer with over 40 years in waveguide component production for satellite and wireless communications. Leveraging data from the company’s ERP system, including historical purchase orders, supplier evaluations, and expenditure trends, the study identifies gaps in the existing supplier evaluation process and offers strategic enhancements. The proposed model enriches supplier assessment by integrating key objective metrics such as lead time, quality, and price, along with subjective factors like communication, environmental impact, and innovation capability. These additions provide a more comprehensive framework for supplier performance assessment, while a weighted scoring model aligns evaluations with the company’s operational priorities and long-term objectives. Subjective variables are analyzed using fuzzy logic, offering a nuanced perspective on qualitative dimensions.
To implement the model, a dual-method approach is proposed. The first method combines objective and subjective metrics into a single weighted score, while the second uses only objective metrics for the final score, applying subjective scores to adjust supplier categorization. This structured classification system groups suppliers into “Approved,” “Conditional,” “Potential,” or “Rejected” categories, equipping decision-makers with actionable insights for supplier development and risk management. By balancing immediate operational efficiency with strategic partnerships, the model positions the company to strengthen its supply chain and align with evolving industry expectations.
Building on the established framework, this study offers an in-depth model for supplier evaluation and development, integrating insights from both extensive literature and practical case studies. The proposed model emphasizes the importance of strengthening supplier-buyer relationships, which in turn enhances supply chain performance and contributes to the organization’s overall success. Furthermore, the study identifies potential areas for future research, encouraging further investigation into evolving supplier management practices and methodologies
Clinically-Inspired Hierarchical Classification of Chest X-rays with a Penalty-Based Loss Function
No full textIn this study, we propose a novel approach to multi-label classification of chest X-ray (CXR) images that prioritizes clinical interpretability while maintaining the efficiency of a streamlined, single-model, single-run training pipeline. Using the CheXpert dataset and VisualCheXbert-derived labels, we introduce hierarchical label groupings to reflect clinically meaningful relationships among diseases. To implement this, we developed a custom hierarchical binary cross-entropy (BCE) loss function that enforces label dependencies through fixed or data-driven penalty mechanisms. This approach aims to preserve diagnostic accuracy while producing structured and clinically coherent predictions. The official codebase supporting this work is available at https://github.com/the-mercury/CIHMLC.git
Development of Polymeric Abradable Coatings for Aero Engine Applications
Get PDFIn the field of aerospace engineering, the enhancement of engine performance and reliability under extreme conditions is paramount. This study is dedicated to the development of polymeric abradable coatings for fan core and Low-Pressure Compressor stage. These coatings are specifically engineered to wear away in a controlled manner, thus reducing friction and improving the sealing capabilities of engines, a critical factor for optimizing efficiency.
The research evaluates two primary material types: thermosets and thermoplastics, comparing them against two commercially available materials which are epoxy based and named as ref1 and ref2. The assessment involves a series of tests, including erosion resistance, tribology pin-on-flat testing, and rub rig testing, to gauge the performance of these materials under operational stress.
Furthermore, the study explores the incorporation of various fillers—Graphite, Silicone Powder, PTFE, Carbon Nanotubes, Milled Carbon Fiber, Aramid Fiber, and Hollow Glass Microspheres—into selected thermoset. These fillers are evaluated at two distinct concentrations to ascertain their influence on erosion resistance.
Through this research, effective filler concentrations were identified, optimizing the balance between wear resistance and erosion resistance. Notably, a formulation comprising Epoxy with 10% PTFE, and 0.1% Carbon Nanotubes introduced as a potential abradable coating, exceeding the commercial benchmarks in terms of both erosion resistance and friction reduction.
This investigation underscores the critical role of precise material selection in the development of advanced abradable coatings that enhance the efficiency and longevity of aircraft turbine components, offering implications for future aerospace applications
Increase in Liposome Production: From Microfluidics to Milli-fluidics
Get PDFLiposomes are tiny vesicles of lipid layers enclosing medication for drug delivery, mostly used in cancer treatment, gene therapy and mRNA vaccines. One of the production technologies implies the use of microfluidic mixers, which produce liposomes at a very low yield. Previous research proved the viability of liposome production but at a very low yield. Based on the successful results of the liposome production at micro-scale, the assumption that scaling up the channel size may lead to an increased production of similar-sized liposomes. To begin evaluating its feasibility, simulations of the mixing of two fluids within scaled up channels were carried out. The objective of the simulations are to evaluate the mixing potential prior to experimental trials. Same linear velocity values and mixing ratio were considered in simulations. However, from the mathematical model, the resulting size of the liposomes cannot be predicted. It may be possible that along with larger channels, larger liposomes might be produced. The same fluid properties will be used during the mixing of a solution containing lipids and alcohol with water, which will result in liposomes formation in both micro and milli channels. The hypothesis behind this experiment states that the size of the liposome depends on the speed of mixing, which is bounded by fluid flow properties, such as velocity, pressure and concentration, that will need to remain similar in values in the enlarged microfluidic device. During simulation, similar mixing results were obtained as the base research, which indicate good mixing efficiency when scaling up the cross-section area by 10 and 25 times.. It seems that it may be possible to increase production of liposomes through larger devices if the pressure inside the channels is increased due to higher flow rate, which is also scaled by a factor corresponding to the dimension increase. A larger production rate could be a game changer in the pharma industry. Preliminary experiments yield liposomes of increased size - by 20 to 50% in diameter at a significant increase in productivity
Renting Servers in the Cloud
Get PDFWe study the Renting Servers in the Cloud problem (\RSiC), which addresses the need for efficient job allocation in cloud computing applications. Jobs arrive in an online manner and need to be assigned to servers. The size of each job is known at the time of arrival. If the duration of the jobs is also known, the scenario is termed clairvoyant; if the duration is unknown, it is non-clairvoyant. An infinite supply of identical servers is available, each providing one unit of computational capacity per unit of time across all dimensions. A server can be rented at any time and remains rented until all assigned jobs are completed. The cost of an assignment is the sum of the rental periods of all servers. The objective is to allocate jobs to servers in a way that minimizes the overall cost while adhering to server capacity constraints.
We first focus on a scenario where all jobs have equal durations and analyze the performance of two natural algorithms, \NF and \FF. We establish a tight bound of on the competitive ratio of \NF. For \FF, we also prove bounds under several restrictions. Next, we conduct a parameterized analysis of \FF, examining inputs where it utilizes at most servers simultaneously. We support the theoretical analysis with extensive experimental studies. Then, we show for a large class of well-known algorithms for \RSiC, none of them always outperforms the others.
We study the multi-dimensional \RSiC setting, where jobs/servers have multi-parameter resource demands/capacities (e.g., cores, memory). We demonstrate a direct sum property of \RSiC. We also propose a novel clairvoyant algorithm called \Greedy; our experiments demonstrate its superiority over existing algorithms in most scenarios. We introduce and analyze performance of a new sub-family of \AF algorithms termed monotone \AF, which includes \Greedy, \FF, \LF, and \MTFtext.
Finally we evaluate both clairvoyant and non-clairvoyant algorithms for \RSiC on real-world data using the Azure dataset. The results are sometimes different from those previously obtained on synthetic data. We also proposed some new algorithms that are combinations of known algorithms and outperform all existing algorithms in our experiments
Social Interaction and Cultural Activities: A Theoretical and Empirical Analysis of Friendship Networks
Get PDFThis thesis consists of three chapters on social networks, focusing on cultural activities and social interactions.
Chapter 2 introduces a model of friendship formation that explores whether cultural activities can help reduce segregation across racial groups. The model incorporates a bias in the matching process, where individuals engaged in the same activities are more likely to form friendships. This framework aligns with empirical findings, including increased friendships among club members and reduced segregation when students from different racial backgrounds participate equally in cultural activities.
Chapter 3 presents an empirical analysis of club participation, examining how individual decisions are shaped by social norms. The findings indicate that white students participating in basketball and black students in baseball are influenced by the size of their racial group, whereas this effect is not observed for the reverse combinations. Using a Linear-in-Mean (LIM) model, the study reveals that previous research may overestimate peer effects on individual decisions, mainly due to the endogeneity of friendship networks. The results suggest that cultural clubs play a role in fostering social cohesion across racial groups.
Chapter 4 presents a model that examines how social norms influence students' decisions to participate in clubs, highlighting a trade-off between the costs of participation and the benefits of social engagement. The model predicts that as school size increases, participation rates decline, but a higher proportion of devotee members are committed to the club. Moreover, social engagement has a stronger influence on participation decisions in larger schools. Empirical data support these predictions
A Comparative Study of Social Media’s Religiopolitical Use by Pakistan Tehrike-Insaf (PTI) and Tehrik-e-Labbaik Pakistan (TLP)
Get PDFThe political abuse of social media platforms like Facebook and X (formerly Twitter) has further complicated the religiopolitical dynamics in Pakistan. This study intends to understand the use of Facebook and X in the political journey of Pakistan Tehrik-e-Insaf (PTI), a mainstream political party, and Tehrik-e-Labbaik Pakistan (TLP), a religiopolitical party. A comparative literature review was conducted to critically analyze the peer-reviewed literature to identify the ways PTI and TLP have used Facebook and X to establish and nurture their political ideologies, particularly among youth. The findings of the content analysis revealed that both parties significantly benefitted from Facebook and X to project their political agenda, instill religion (Islam) in their political campaigns, and organize massive (violent) protests. The paper also provides contextual knowledge on social media platforms like Facebook and X being used in religiopolitical discourses and influencing the political attitude of netizens, particularly youth. This study argues that social media has shifted Pakistan’s political dynamics such as electioneering, voter campaigns, and sustaining political control, which has caused increased religiopolitical radicalism among youth
Game On: Early Stories
No full textGame On is a collection of linked short stories that explore the lives of several inner-city youth of diverse backgrounds, growing up in Montreal. These characters’ misadventures are intertwined through their participation in a basketball team made up of students from various alternative schools around the city. The stories touch on topics affecting vulnerable teens, such as poverty, addiction, gang affiliation, violence, neglect and trauma. The most prominent themes arise from the travails of adolescence, such as coming to terms with absent or unreliable parental figures, establishing value systems around materialism and friendship, and developing a sense of humanism in a seemingly indifferent world. These ideas are explored through the unique affect of growing up as at-risk anglophone youth in Montreal—minority citizens both linguistically and often ethnically, caught up in the collateral ravages of Quebec’s cultural identity crisis. Above all, the stories promote the importance of having positive role models, establishing healthy community connections, and encouraging creative thinking as a means of survival
Plasto-Art: Neo-traditionalism – a decolonized journaling of indigenous Igbo (non)material culture through the eco-aesthetic practice of the Ikpa isi owu traditional (hair)craft
No full textReclamation of discarded material objects and cultural forms should not end in the physical aesthetic juxtaposition of both, whether in protest of our high-culture environment and the nuances of beauty, as is often seen in subversive forms of most contemporary art practices. Neither should the idea of re-use be allowed to drift into mere panoply of reclaimed materials within the spectrum of art creation. Rather, there should be clear alliances to formulate interventions, which not only identifies and challenges our environmental exigencies but also formulate processes and methods of making and remaking to bring a balance between the depleting environment, its replenishment and continuity. Therefore, this research-creation thesis, through the ecological channels inherited from traditional Nigerian craft practices, responds to that intervention by defining a specific and unique path despite what is applicable on a universal platform. Just as the methodologies that inform this research are unconventional so will the style of documentation and discussion you will find here be different from the conventional academic format of written scholarship. It will be more akin to the traditional pedagogic mannerisms of oral lore manifested through visual descriptive interpretations adapted from an alignment with my historical Nigerian (Igbo) heritage. The nature of this research-creation departs from accounts which permeate the regular spectrum of normative documentation and interpretation of research findings. Today’s academic environment must give room for shifts in methods of modern learning and can only be encompassing when indigenous scholarship and research methods have equal acknowledgement