Optimizing materialized view selection for spatial queries in hybrid transactional/analytical processing database

In this project, we aimed to develop Hybrid Transactional/Analytical Processing (HTAP) database that enables efficient analytical and transaction processing on the same in-memory data store. Specifically, we extended the architecture to handle spatial data, enabling efficient querying and processing of geospatial information commonly used in location-based analysis. As real-time geospatial data becomes increasingly central to modern applications, HTAP architecture that support both fresh data ingestion and low-latency spatial querying have grown in importance. To support this, we employed a combination of Materialized View generation techniques and a write-optimized storage engine. MyRocks, a write-optimized storage engine for MySQL based on RocksDB, was used for this project. MyRocks storage engine offers high performance for write-intensive operations and efficient data compression. To improve the reading performance, precomputed queries, better known as Materialized Views, were leveraged. This allowed the overall architecture to have a balanced approach that efficiently handles both write-intensive transactional workloads and read-intensive analytical queries. To evaluate the performance of the proposed HTAP system, we utilized a real-world spatial workload comprising over 187,000 city geometries, 65,000 geotagged tweets, and 9,000 points of interest (POIs). A set of spatial SQL queries was utilized to simulate analytical workloads involving spatial joins, spatial aggregations, vector search, and temporal filters. Efficient processing of these queries was achieved by implementing and comparing several spatially aware Materialized View generation strategies that pre-aggregate data by geographic regions and minimize the cost of spatial joins and filtering during query execution. The results demonstrated that these strategies significantly improved query performance, with some complex spatial queries seeing a reduction from over one hour to under 20 seconds. In conclusion, the proposed Hybrid Transactional/Analytical Processing (HTAP) system has shown promising results in addressing the demands of transactional and analytical processing on the same data store, particularly for spatial workloads. The combination of MyRocks' write-optimized capabilities and the strategic use of Materialized View demonstrated substantial improvements in query performance. Future work may focus on integrating this approach into a larger open-sourced geospatial database system to support real-world spatial analytics.Bachelor's degre

Fe-redox-oriented electrochemical activation strategy enabling enhancement for efficient oxygen evolution reaction

Creating highly effective electrocatalysts requires understanding how materials change under varied electrochemical conditions. While much effort has been devoted to investigating structural changes under operational conditions, deliberately exposing catalysts to non-operational potential regions to electrochemically activate the catalysts and improve the catalytic performance is an underexplored area. Enlightened by the fact that Fe species exhibit pronounced redox responses in alkaline solutions within a potential range that notably falls below the oxygen evolution reaction (OER) potential region, we propose an Fe-redox-oriented electrochemical activation approach to effectively alter the catalysts’ OER performance. This approach, involving pre-cycling catalysts within the Fe-redox-rich potential range, significantly enhances the OER performance of various Fe-containing materials. For the representative Fe3O4@NiO catalyst, this enhancement is primarily attributed to the formation of heterojunctions and a mixed Ni-Fe surface component, which results in a more favorable electronic structure for OER.Agency for Science, Technology and Research (A*STAR)Submitted/Accepted versionThe authors acknowledge support from the National Natural Science Foundation of China (22209109 and 22479096), the Science and Technology Commission of Shanghai Municipality (Yangfan Project, 22YF1419500), and the Agency for Science, Technology and Research (A*STAR) through the Low Carbon Energy Research Funding Initiative (LCERFI01-0033 and U2102d2006)

An empirical study of convolution-based and transformer-based diffusion models

This project presents an empirical comparison between convolution-based U-Net and transformer-based DiT-S/2 diffusion models on the CIFAR-10 dataset. To address the lack of spatial inductive bias in DiT, we implement three architectural enhancements: Frequency-Based Noise Control (FNC), Overlapping Patch Embeddings (OPE), and Adaptive Positional Encoding (APE). Results show that DiT-S/2 outperforms U-Net in semantic diversity (IS: 5.02 vs. 4.56), but lags in structural fidelity (PSNR: 5.84 vs. 7.65, SSIM: 0.03 vs. 0.04). OPE and APE improve DiT’s image quality, while FNC sig- nificantly reduces inference time. These findings highlight the importance of architectural priors in improving transformer-based diffusion, especially for low-resolution tasks. We hypothesize that similar trends will hold in larger DiT variants, given more training re- sources. This study offers practical insights into enhancing transformer-based generative models through targeted inductive bias.Bachelor's degre

SkillMart: skills sharing and marketplace platform

This project focuses on a addressing the gap between the rising popularity of online education platforms and customer-to-customer marketplace platforms by developing a software solution dedicated to peer-to-peer skills and knowledge exchange, SkillMart. A market analysis shows that SkillMart is feasible by targeting low to middle income extroverted students and young adults who are seeking for jobs or freelancing with penetration pricing strategies such as the freemium model. Design considerations were then drawn up based on design principles such from the field of Human Computer Interaction, followed by a wireflow low-fidelity prototype adhering to the established initial design considerations. To identify problems early and to ensure that the user interface aligns with the expectations of potential users from the target segment, a multi-modal evaluation study was conducted with target users as well as experts with experience in the design of user interfaces. While the evaluation indicated positive reception to the design, several flaws and rooms for improvement were pointed out, and several participants indicated desire for inclusion of more complex and advanced features such as collaborative tools. With the feedback and insights of the initial evaluation study in mind, the initial design considerations were refined with more detailed use cases, though the inclusion of desired additional features were not included but kept in view for future work. Use case specifications, a use case diagram, and sequence diagrams were created to guide the next stage of development, which was the development of the high-fidelity prototype. The high-fidelity prototype was developed drawing concepts from various fields such as database design, software security, artificial intelligence and search engine optimisation. Following the code implementation of the high-fidelity prototype, comprehensive testing was conducted which included automated unit tests and manual integration and end-to-end tests. Finally, with a working prototype, a second round of evaluation study was conducted, this time focusing more on the objective usability measurements rather than subjective satisfaction. The evaluation study concluded indicating that the insights from the first round of evaluation studies had been valuable in improving the user interface and helping to develop a highly usable user interface. However, few flaws were also introduced due to the changes made in the design, highlighting a continuous need for iterative improvements in the design lifecycle of software development. With the satisfactory results from the second evaluation study, the stage is set for future work such as the addition of complex desired features in SkillMart.Bachelor's degre

One-Stop knowledge centre for course modules

Ensuring good interaction between students and lecturers is a central issue for universities around the world. In response to this, the “One-stop Knowledge Centre for Course Modules” is designed as a web-based system for the College of Computing and Data Science (CCDS) at Nanyang Technological University (NTU). The system integrates interactive rubrics for evaluation that promote engaged participation and teamwork, along with discussion forums and a comprehensive knowledge base. Through the creation of an interactive educational space, the system enriches the learning experience, promotes communication, and encourages ongoing interaction among students and educators. The comprehensive strategy is designed to ensure the highest academic achievement and create a vibrant academic community.Bachelor's degre

Crowd sensing using deep learning

Crowd density has risen across the worlds as the human population increases across the past decades. This get worse as people tends to gather into cities and may cause a strain on certain facilities when they are being overused or cause accidents due to overcrowding. Many newer model for crowd counting task employ the density map approach. Density map approach is good for estimating people count in a very dense image but lacks interpretability in the model’s prediction and accuracy. These models were also not built with the consideration of using it for crowd surveillance tasks but more so focus on getting the best accuracy on the images. This report will go through the different deep learning models used for crowd counting and implement and train a model that deem the most fit for common crowdsurveillance purposes. It will still be evaluated against the different models and a website will be built around the model to show the use of such model in practical situations.Bachelor's degre

Controllable image generation and editing

This paper presents a comprehensive exploration of text-to-image generation, examin- ing the current state-of-the-art models, available fine-tuning techniques using LoRAs, and the limitations that come with them. In addition to this survey, we propose a method that enhances user control over image outputs, enabling more targeted and cus- tomizable generations. Our method demonstrated strong performance across various styles and subjects. We also explored how a distinction between styles highlights the importance of adapting generation approaches based on stylistic intent. We also outline key strategies and fine-tuning practices that can significantly improve generation qual- ity, regardless of the underlying model or method. These insights aim to equip users with both the understanding and practical tools needed to optimize their text-to-image workflows.Bachelor's degre

Integrated controller system of PEMFC

Proton Exchange Membrane Fuel Cells (PEMFC) have emerged as promising alternatives to conventional energy sources due to their high efficiency and eco-friendly operation. However, operational challenges related to thermal regulation and anode purging significantly affect their performance and durability. Furthermore, existing commercial products that bundle a controller and fuel cell can be prohibitively costly and inflexible for smaller-scale research experiments. This study proposes and develops a simplified, cost-effective integrated controller for PEMFC systems, utilizing Arduino-based hardware to automate thermal management via a DC fan and anode purging through a solenoid valve Real-time monitoring is achieved using TMP36 temperature sensors, ACS712 current sensors, and voltage sensors. Experimental verification demonstrates that the integrated controller maintains stable operating conditions and sustains hydrogen purity through periodic anode purging intervals but yields inconclusive results regarding the effectiveness of DC fan cooling, primarily due to the use of an aging PEMFC stack that was unable to generate sufficient power – and thus heat - for proper testing. Nevertheless, the results demonstrate the promising viability of a threshold-based controller for small-scale PEMFC applications, significantly reducing cost barriers and complexity compared to existing commercial solutions. This research paves the way for broader accessibility and flexibility in PEMFC technology deployment, particularly in educational and prototype development scenarios.Bachelor's degre

Rational engineering of microalgae for food applications

As the impacts of climate change continue to emerge and the global population is on constant rise, this renders escalating demand for sustainable food sources. Microalgae have then garnered increasing interest as a promising food alternative since they are rich in nutrient content, rapid growth rates, and require less resources for cultivation especially for freshwater microalgae. Among the freshwater species, Chlorella vulgaris and Chlorella sorokiniana have gained prominence for their potential in food applications. However, large-scale cultivation remains challenging owing to the presence of environmental stressors that affect biomass yield and biochemical stability of the freshwater microalgae. This study aims to investigate the growth responses of C. vulgaris and C. sorokiniana in relation to their stress tolerance under a range of abiotic stress conditions relevant to industrial cultivation. A systematic 12-day growth profile study was conducted under controlled conditions focusing on four stressors which include heavy metals (CoCl₂, CuSO₄), endoplasmic reticulum stress (DTT) and oxidative stress (H₂O₂). Optical density measurements (OD₆₈₀) were used to monitor growth kinetics. Moreover, selected stress treatments and subsequent RNA extractions were performed to prepare for RNA sequencing in the future. The results obtained from the growth profile study potentially indicate species-specific tolerance patterns, where C. sorokiniana exhibiting greater resilience to cobalt stress, while C. vulgaris showed higher tolerance to copper stress, DTT-induced endoplasmic reticulum stress and H2O2-induced oxidative stress. In general, significant growth suppression was observed at higher concentrations across all stressors, with notable declines in chlorophyll-associated absorbance at OD₆₈₀. These findings provide comparative insights into the stress physiology of two industrially relevant microalgae species and lay the groundwork for rational strain selection via genetic engineering, which helps to improving microalgae robustness for food applications.Bachelor's degre

Evaluation of enzymatic degradation of petase against PBT and PEN nanoplastics using dye release assay

Plastic pollution poses a significant environmental challenge in recent years, driving interest in enzymatic degradation of plastic as one of the sustainable solutions. This study focuses on the expression, purification, and activity testing of different variants (WT, V3 and FAST) of PETase, an enzyme known to degrade polyethylene terephthalate (PET), using Escherichia coli (E. coli) SHuffle cells as the expression host. Following purification, the enzymatic activity of PETase was assessed on plastic-based nanoparticle substrates, specifically polyethylene naphthalate (PEN) and polybutylene terephthalate (PBT). Substrate degradation was monitored by a dye release assay using plastic nanoparticle- encapsulated dyes, Acridine Orange (AO) and Toluidine Blue O (TBO), providing an effective method for quantifying degradation. Fluorescence measurements obtained via spectrophotometry were found correlated with high-performance liquid chromatography (HPLC) data, which served as a reference standard for validation. This work contributes to the growing field of biocatalytic plastic degradation and highlights the potential for fluorescence-based assays in rapid enzyme screening.Bachelor's degre